WorldWideScience

Sample records for high pressure helium

  1. Diagnostics of a High Pressure Helium Microplasma

    Science.gov (United States)

    Wang, Qiang; Koleva, Ivanka; Economou, Demetre; Donnelly, Vincent

    2004-09-01

    Gas and plasma diagnostics were performed in a slot-type DC microplasma (200 microns gap) discharge at high pressures. The gas temperature in a helium discharge was estimated by adding small quantities of nitrogen (excimer. At 250 Torr pressure and 200 mA/cm2 current density, the gas temperature was Tg = 350 +/- 25 K. The measured gas temperature was almost independent (to within experimental uncertainty) of pressure (in the range of 150 Torr - 600 Torr), and current density (in the range of 100 mA/cm2 - 400 mA/cm2). These measurements were consistent with a simple heat transfer model. Spatially resolved measurements of electron temperature were also performed using trace rare gas optical emission actinometry (TRG-OES). These measurements are greatly complicated by collisional quenching at the high operating pressures. Electron density and electron temperature profiles was deduced by comparing emission intensities from the Paschen 2px (x = 1-10) manifold of Ne, Ar, Kr and Xe trace gases. Results suggested that the electron temperature peaks in the cathode sheath region, while the plasma density peaks away from the cathode sheath. A self-consistent fluid model of a DC helium microdischarge was in agreement with the experimental data. The model was used to study the dependence of discharge characteristics on operating conditions (pressure, gap spacing, current density, etc.).

  2. High Efficiency Regenerative Helium Compressor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Helium plays several critical rolls in spacecraft propulsion. High pressure helium is commonly used to pressurize propellant fuel tanks. Helium cryocoolers can be...

  3. Effect of high-pressure helium on latex-induced activated chemiluminescence of human blood leucocytes.

    Science.gov (United States)

    Tyurin-Kuz'min, A Yu; Vdovin, A V

    2003-09-01

    High-pressure helium reduces the latex-induced activated chemiluminescence of diluted human blood. This effect is more noticeable, when lucigenin rather than luminol is used as the activator of chemiluminescence. The effect lessens in the presence of Mg2+ but not Ca2+. The data suggest the association of this effect with actin polymerization in leucocytes phagocytosing the latex particles.

  4. Phase equilibria in molecular hydrogen-helium mixtures at high pressures

    Science.gov (United States)

    Streett, W. B.

    1973-01-01

    Experiments on phase behavior in hydrogen-helium mixtures have been carried out at pressures up to 9.3 kilobars, at temperatures from 26 to 100 K. Two distinct fluid phases are shown to exist at supercritical temperatures and high pressures. Both the trend of the experimental results and an analysis based on the van der Waals theory of mixtures suggest that this fluid-fluid phase separation persists at temperatures and pressures beyond the range of these experiments, perhaps even to the limits of stability of the molecular phases. The results confirm earlier predictions concerning the form of the hydrogen-helium phase diagram in the region of pressure-induced solidification of the molecular phases at supercritical temperatures. The implications of this phase diagram for planetary interiors are discussed.

  5. Quartz Tuning Fork Pressure Gauge for High-Pressure Liquid Helium

    Science.gov (United States)

    Botimer, J.; Velasco, A.; Taborek, P.

    2017-01-01

    We have measured the quality factor Q and the frequency f of a 32-kHz quartz tuning fork immersed in liquid ^4He between 0.9 and 3.0 K, over pressures ranging from the saturated vapor pressure to ≈ 25 atm. At constant pressure, as a function of temperature, the quality factor and frequency have strong features related to the temperature dependence of the superfluid fraction. At constant temperature, Q depends on the superfluid fraction, while the frequency is a smooth function of pressure. The behavior is explained using a simple hydrodynamic model. The liquid helium viscosity is obtained from measured values of Q, and together with tabulated values of the helium density as a function of pressure and temperature, the frequency shift can be parameterized as a function of temperature and pressure. The observed sensitivity is ≈ 7.8 Hz/atm. The quartz tuning fork provides a compact low power method of measuring the pressure in the bulk liquid.

  6. High pressure real gas effects for helium and nitrogen

    Science.gov (United States)

    Johnson, R. C.

    1969-01-01

    Critical flow factor is calculated that permits the isentropic mass-flow rate of the gases through critical flow nozzles to be calculated from plenum conditions. Results include nozzle throat velocity, compressibility factor, entropy, enthalpy, specific heat, and ratios of throat to plenum pressure, density, and temperature.

  7. Pressure drop and blower performance tests in very high temperature Helium Experimental LooP (HELP)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Soo; Hong, Sung Deok; Kim, Yong Wan [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Korea Atomic Energy Research Institute (KAERI) has developed the gas loops to develop and verify the key components of the nuclear hydrogen production system. At the present, KAERI is operating a small scale gas loop for feasibility tests of process heat exchanger and a very high temperature Helium Experimental LooP (HELP) for verification tests of bench scale prototypes for high temperature key components in Very High Temperature gas cooled Reactor (VHTR). Figure 1 presents the HELP assembled with the key components. The size was designed for the verification test of a 150kW intermediate heat exchanger or the simulation test in a 1/6 scaled down fuel block. The loop consists of the primary loop and the secondary loop. The primary loop and the secondary loop simulate VHTR and intermediate loop in nuclear hydrogen production system, respectively. The loops were designed to withstand the maximum temperature of 1000 .Deg. C, the maximum pressure of 9.0 MPa, and the normal mass velocity of 0.5 kg/sec. The working fluid is helium as the actual coolant of VHTR. The primary loop is composed of a preheater, a high temperature heater, a hot gas duct, intermediate heat exchangers, a water cooled U tube heat exchanger, a gas bearing circulator, a passive venting system and gas filters. The secondary loop has the same system configuration as the primary loop except a high temperature heater. Two loops share a helium supply system, a helium purification system and the water loop for a cooling tower as Figure 2. In this study, the experimental results of the bypass line pressure drop and blower performance at the nitrogen condition are analyzed to predict the main line mass flow rates without heaters.

  8. CO2-helium and CO2-neon mixtures at high pressures.

    Science.gov (United States)

    Mallick, B; Ninet, S; Le Marchand, G; Munsch, P; Datchi, F

    2013-01-28

    The properties of mixtures of carbon dioxide with helium or neon have been investigated as a function of CO(2) concentration and pressure up to 30 GPa at room temperature. The binary phase diagrams of these mixtures are determined over the full range of CO(2) concentrations using visual observations and Raman scattering measurements. Both diagrams are of eutectic type, with a fluid-fluid miscibility gap for CO(2) concentrations in the range [5, 75] mol. % for He and [8, 55] mol. % for Ne, and a complete separation between the two components in the solid phase. The absence of alloys or stoichiometric compounds for these two binary systems is consistent with the Hume-Rothery rules of hard sphere mixtures. The Raman spectra and x-ray diffraction patterns of solid CO(2) embedded in He or Ne for various initial concentrations have been measured up to 30 GPa and 12 GPa, respectively. The frequencies of the Raman modes and the volume of solid phase I are identical, within error bars, to those reported for 100% CO(2) samples, thus confirming the total immiscibility of CO(2) with He and Ne in the solid phase. These results demonstrate the possibility to perform high-pressure experiments on solid CO(2) under (quasi-)hydrostatic conditions using He or Ne as pressure transmitting medium.

  9. Experimental study of forced convection heat transfer during upward and downward flow of helium at high pressure and high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Francisco Valentin; Narbeh Artoun; Masahiro Kawaji; Donald M. McEligot

    2015-08-01

    Fundamental high pressure/high temperature forced convection experiments have been conducted in support of the development of a Very High Temperature Reactor (VHTR) with a prismatic core. The experiments utilize a high temperature/high pressure gas flow test facility constructed for forced convection and natural circulation experiments. The test section has a single 16.8 mm ID flow channel in a 2.7 m long, 108 mm OD graphite column with four 2.3kW electric heater rods placed symmetrically around the flow channel. This experimental study presents the role of buoyancy forces in enhancing or reducing convection heat transfer for helium at high pressures up to 70 bar and high temperatures up to 873 degrees K. Wall temperatures have been compared among 10 cases covering the inlet Re numbers ranging from 500 to 3,000. Downward flows display higher and lower wall temperatures in the upstream and downstream regions, respectively, than the upward flow cases due to the influence of buoyancy forces. In the entrance region, convection heat transfer is reduced due to buoyancy leading to higher wall temperatures, while in the downstream region, buoyancyinduced mixing causes higher convection heat transfer and lower wall temperatures. However, their influences are reduced as the Reynolds number increases. This experimental study is of specific interest to VHTR design and validation of safety analysis codes.

  10. Primary helium heater for propellant pressurization systems

    Science.gov (United States)

    Reichmuth, D. M.; Nguyen, T. V.; Pieper, J. L.

    1991-01-01

    The primary helium heater is a unique design that provides direct heating of pressurant gas for large pressure fed propulsion systems. It has been conceptually designed to supply a heated (800-1000 R) pressurization gas to both a liquid oxygen and an RP-1 propellant tank. This pressurization gas is generated within the heater by mixing super critical helium (40-300 R and 3000-1600 psi) with an appropriate amount of combustion products from a 4:1 throttling stoichiometric LO2/LH2 combustor. This simple, low cost and reliable mixer utilizes the large quantity of helium to provide stoichiometric combustor cooling, extend the throttling limits and enhance the combustion stability margin. Preliminary combustion, thermal, and CFD analyses confirm that this low-pressure-drop direct helium heater can provide the constant-temperature pressurant suitable for tank pressurization of both fuel and oxidizer tanks of large pressure fed vehicles.

  11. Existence of liquid helium above melting curve pressures

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, A.L.; Brewer, D.F.; Naji, T.; Haynes, S. (Sussex Univ., Brighton (UK). Dept. of Physics); Reppy, J.D. (Cornell Univ., Ithaca, NY (USA))

    Data are presented on the specific heat of helium confined at a high externally applied pressure within the 60 A pores of vycor glass. The specific heat shows that the helium within the pores remains in the liquid state down to temperatures well below 1 K. On the other hand the helium outside the vycor behaves normally, changing phase from solid to liquid as it warms.

  12. A high-pressure van der Waals compound in solid nitrogen-helium mixtures

    Science.gov (United States)

    Vos, W. L.; Finger, L. W.; Hemley, R. J.; Hu, J. Z.; Mao, H. K.; Schouten, J. A.

    1992-01-01

    A detailed diamond anvil-cell study using synchrotron X-ray diffraction, Raman scattering, and optical microscopy has been conducted for the He-N system, with a view to the weakly-bound van der Waals molecule interactions that can be formed in the gas phase. High pressure is found to stabilize the formation of a stoichiometric, solid van der Waals compound of He(N2)11 composition which may exemplify a novel class of compounds found at high pressures in the interiors of the outer planets and their satellites.

  13. Stability of the high-pressure body-centered-cubic phase of helium

    NARCIS (Netherlands)

    Frenkel, D.

    1986-01-01

    This paper report absolute free-energy calculations of the fluid, body-centered-cubic, and face-centered-cubic phases of helium at T=327.04 K. We find that at and around this temperature the model potential proposed by Aziz et al. doe not yield a stable bcc phase. Quantum corrections do not alter th

  14. Stability of the high-pressure body-centered-cubic phase of helium

    OpenAIRE

    Frenkel, D.

    1987-01-01

    This paper report absolute free-energy calculations of the fluid, body-centered-cubic, and face-centered-cubic phases of helium at T=327.04 K. We find that at and around this temperature the model potential proposed by Aziz et al. doe not yield a stable bcc phase. Quantum corrections do not alter this conclusion

  15. Liquid Oxygen Thermodynamic Vent System Testing with Helium Pressurization

    Science.gov (United States)

    VanDresar, Neil T.

    2014-01-01

    This report presents the results of several thermodynamic vent system (TVS) tests with liquid oxygen plus a test with liquid nitrogen. In all tests, the liquid was heated above its normal boiling point to 111 K for oxygen and 100 K for nitrogen. The elevated temperature was representative of tank conditions for a candidate lunar lander ascent stage. An initial test series was conducted with saturated oxygen liquid and vapor at 0.6 MPa. The initial series was followed by tests where the test tank was pressurized with gaseous helium to 1.4 to 1.6 MPa. For these tests, the helium mole fraction in the ullage was quite high, about 0.57 to 0.62. TVS behavior is different when helium is present than when helium is absent. The tank pressure becomes the sum of the vapor pressure and the partial pressure of helium. Therefore, tank pressure depends not only on temperature, as is the case for a pure liquid-vapor system, but also on helium density (i.e., the mass of helium divided by the ullage volume). Thus, properly controlling TVS operation is more challenging with helium pressurization than without helium pressurization. When helium was present, the liquid temperature would rise with each successive TVS cycle if tank pressure was kept within a constant control band. Alternatively, if the liquid temperature was maintained within a constant TVS control band, the tank pressure would drop with each TVS cycle. The final test series, which was conducted with liquid nitrogen pressurized with helium, demonstrated simultaneous pressure and temperature control during TVS operation. The simultaneous control was achieved by systematic injection of additional helium during each TVS cycle. Adding helium maintained the helium partial pressure as the liquid volume decreased because of TVS operation. The TVS demonstrations with liquid oxygen pressurized with helium were conducted with three different fluid-mixer configurations-a submerged axial jet mixer, a pair of spray hoops in the tank

  16. High-pressure phase diagram and equation of state of solid helium from single-crystal X-ray diffraction to 23.3 GPa

    Science.gov (United States)

    Mao, H. K.; Hemley, R. J.; Jephcoat, A. P.; Finger, L. W.; Wu, Y.

    1988-01-01

    Single-crystal X-ray diffraction measurements have been performed on solid He-4 from 15.6 to 23.3 GPa at 300 K with synchrotron radiation. The diffraction patterns demonstrate that the structure of the solid is hexagonal close packed over this pressure-temperature range, contrary to both the interpretation of high-pressure optical studies and to theoretical predictions. The solid is more compressible than is indicated by equations of state calculated with recently determined helium pair potentials. The results suggest that a significant revision of current views of the phase diagram and energetics of dense solid helium is in order.

  17. Discharge instabilities in high-pressure helium-fluorine laser gas mixtures

    Science.gov (United States)

    Mathew, D.; Bastiaens, H. M. J.; Peters, Peter J. M.; Boller, Klaus-Jochen

    2005-03-01

    Discharge instabilities in F2 based excimer gas lasers are investigated using a small-scale discharge system. After preionizing the gas volume, a fast rising voltage pulse initiates the discharge. The temporal development of the discharge is monitored via its fluorescence by an intensified CCD camera with a gating time of 10 ns. Homogeneous discharges are produced in gas mixtures of He/1mbar F2 and He/1mbar F2/30mbar Xe at a total pressure of 2 bar for pump pulse duratins up to 70 ns (FWHM). The addition of Xe to He/F2 mixture does not lead to discharge instabilities while the introduction of more F2 results in hotspot and filament formation.

  18. On the role of helium molecules in atmospheric pressure discharges

    Science.gov (United States)

    Carbone, Emile; Schregel, Christian; Luggenhölscher, Dirk; Czarnetzki, Uwe

    2016-09-01

    Despite their intrinsic simplicity, helium plasma kinetics are still not fully understood and quantitatively described. This is particularly the case at high pressures when various molecular helium species (i.e. ions, excimer(s) and Rydberg states) are formed. In this contribution, the absolute density of helium Rydberg molecules is measured for the first time by a combination of laser photo-ionization and Thomson scattering experiments. The experiments are performed on a parallel plate, nanosecond pulsed, DC discharge at 700 mbar. The results are combined with electron and helium metastable densities measurements and compared with a kinetic model of the discharge. The source of He2 molecules in the discharge and afterglow phases are identified and discussed. The present experimental data and kinetic model solve several inconsistencies between reaction paths proposed in the literature.

  19. Cold Helium Gas Pressurization For Spacecraft Cryogenic Propulsion Systems

    Science.gov (United States)

    Morehead, Robert L.; Atwell. Matthew J.; Hurlbert, Eric A.; Melcher, J. C.

    2017-01-01

    To reduce the dry mass of a spacecraft pressurization system, helium pressurant may be stored at low temperature and high pressure to increase mass in a given tank volume. Warming this gas through an engine heat exchanger prior to tank pressurization both increases the system efficiency and simplifies the designs of intermediate hardware such as regulators, valves, etc. since the gas is no longer cryogenic. If this type of cold helium pressurization system is used in conjunction with a cryogenic propellant, though, a loss in overall system efficiency can be expected due to heat transfer from the warm ullage gas to the cryogenic propellant which results in a specific volume loss for the pressurant, interpreted as the Collapse Factor. Future spacecraft with cryogenic propellants will likely have a cold helium system, with increasing collapse factor effects as vehicle sizes decrease. To determine the collapse factor effects and overall implementation strategies for a representative design point, a cold helium system was hotfire tested on the Integrated Cryogenic Propulsion Test Article (ICPTA) in a thermal vacuum environment at the NASA Glenn Research Center Plum Brook Station. The ICPTA vehicle is a small lander-sized spacecraft prototype built at NASA Johnson Space Center utilizing cryogenic liquid oxygen/liquid methane propellants and cryogenic helium gas as a pressurant to operate one 2,800lbf 5:1 throttling main engine, two 28lbf Reaction Control Engines (RCE), and two 7lbf RCEs (Figure 1). This vehicle was hotfire tested at a variety of environmental conditions at NASA Plum Brook, ranging from ambient temperature/simulated high altitude, deep thermal/high altitude, and deep thermal/high vacuum conditions. A detailed summary of the vehicle design and testing campaign may be found in Integrated Cryogenic Propulsion Test Article Thermal Vacuum Hotfire Testing, AIAA JPC 2017.

  20. Pressure-Volume-Temperature (PVT) Gauging of an Isothermal Cryogenic Propellant Tank Pressurized with Gaseous Helium

    Science.gov (United States)

    VanDresar, Neil T.; Zimmerli, Gregory A.

    2014-01-01

    Results are presented for pressure-volume-temperature (PVT) gauging of a liquid oxygen/liquid nitrogen tank pressurized with gaseous helium that was supplied by a high-pressure cryogenic tank simulating a cold helium supply bottle on a spacecraft. The fluid inside the test tank was kept isothermal by frequent operation of a liquid circulation pump and spray system, and the propellant tank was suspended from load cells to obtain a high-accuracy reference standard for the gauging measurements. Liquid quantity gauging errors of less than 2 percent of the tank volume were obtained when quasi-steady-state conditions existed in the propellant and helium supply tanks. Accurate gauging required careful attention to, and corrections for, second-order effects of helium solubility in the liquid propellant plus differences in the propellant/helium composition and temperature in the various plumbing lines attached to the tanks. On the basis of results from a helium solubility test, a model was developed to predict the amount of helium dissolved in the liquid as a function of cumulative pump operation time. Use of this model allowed correction of the basic PVT gauging calculations and attainment of the reported gauging accuracy. This helium solubility model is system specific, but it may be adaptable to other hardware systems.

  1. Molecular dynamics study of helium bubble pressure in titanium

    Institute of Scientific and Technical Information of China (English)

    Zhang Bao-Ling; Wang Jun; Hou Qing

    2011-01-01

    In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics (MD) method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble pressure and helium/vacancy ratio; then the dependences of the helium bubble pressure on the bubble radius at different temperatures are studied. It is shown that the product of the bubble pressure and the radius is approximately a constant, a result justifying the pressure-radius relation predicted by thermodynamics-based theory for gas bubble. Furthermore, a state equation of the helium bubble is established based on the MD calculations. Comparison between the results obtained by the state equation and corresponding experimental data shows that the state equation can describe reasonably the state of helium bubble and thus could be used for Monte Carlo simulations of the evolution of helium bubble in metals.

  2. Evaluation of candidate Stirling engine heater tube alloys after 3500 hours exposure to high pressure doped hydrogen or helium

    Science.gov (United States)

    Misencik, J. A.; Titran, R. H.

    1984-01-01

    The heater head tubes of current prototype automotive Stirling engines are fabricated from alloy N-155, an alloy which contains 20 percent cobalt. Because the United States imports over 90 percent of the cobalt used in this country and resource supplies could not meet the demand imposed by automotive applications of cobalt in the heater head (tubes plus cylinders and regenerator housings), it is imperative that substitute alloys free of cobalt be identified. The research described herein focused on the heater head tubes. Sixteen alloys (15 potential substitutes plus the 20 percent Co N-155 alloy) were evaluated in the form of thin wall tubing in the NASA Lewis Research Center Stirling simulator materials diesel fuel fired test rigs. Tubes filled with either hydrogen doped with 1 percent CO2 or with helium at a gas pressure of 15 MPa and a temperature of 820 C were cyclic endurance tested for times up to 3500 hr. Results showed that two iron-nickel base superalloys, CG-27 and Pyromet 901 survived the 3500 hr endurance test. The remaining alloys failed by creep-rupture at times less than 3000 hr, however, several other alloys had superior lives to N-155. Results further showed that doping the hydrogen working fluid with 1 vol % CO2 is an effective means of reducing hydrogen permeability through all the alloy tubes investigated.

  3. Simulation of a non-equilibrium helium plasma bullet emerging into oxygen at high pressure (250-760 Torr) and interacting with a substrate

    Science.gov (United States)

    Yan, Wen; Economou, Demetre J.

    2016-09-01

    A two-dimensional computational study of a plasma bullet emanating from a helium gas jet in oxygen ambient at high pressure (250-760 Torr) was performed, with emphasis on the bullet interaction with a substrate. Power was applied in the form of a trapezoidal +5 kV pulse lasting 150 ns. A neutral gas transport model was employed to predict the concentration distributions of helium and oxygen in the system. These were then used in a plasma dynamics model to investigate the characteristics of the plasma bullet during its propagation and interaction with a substrate. Upon ignition, the discharge first propagated as a surface wave along the inner wall of the containing tube, and then exited the tube with a well-defined ionization front (streamer or plasma bullet). The plasma bullet evolved from a hollow (donut-shaped) feature to one where the maximum of ionization was on axis. The bullet propagated in the gap between the tube exit and the substrate with an average speed of ˜2 × 105 m/s. Upon encountering a metal substrate, the bullet formed a conductive channel to the substrate. Upon encountering a dielectric substrate, the bullet turned into an ionization wave propagating radially along the substrate surface. For a conductive substrate, the radial species fluxes to the surface peaked on the symmetry axis. For a dielectric substrate, a ring-shaped flux distribution was observed. The "footprint" of plasma-surface interaction increased either by decreasing the gap between tube exit and substrate, decreasing the relative permittivity of an insulating substrate, or decreasing pressure. As the system pressure was lowered from 760 to 250 Torr, the discharge was initiated earlier, and the plasma bullet propagation speed increased. A reverse electric field developed during the late stages of the ramp-down of the pulse, which accelerated electrons forming a brief backward discharge.

  4. Neutron Irradiation Tests of Pressure Transducers in Liquid Helium

    CERN Document Server

    Amand, J F; Casas-Cubillos, J; Thermeau, J P

    1999-01-01

    The superconducting magnets of the future Large Hadron Collider (LHC) at CERN will operate in pressurised superfluid helium (1 bar, 1.9 K). About 500 pressure transducers will be placed in the liquid helium bath for monitoring the filling and the pressure transients after resistive transitions. Their precision must remain better than 100 mbar at pressures below 2 bar and better than 5% for higher pressures (up to 20 bar), with temperatures ranging from 1.8 K to 300 K. All the tested transducers are based on the same principle: the fluid or gas is separated from a sealed reference vacuum by an elastic membrane; its deformation indicates the pressure. The transducers will be exposed to high neutron fluence (2 kGy, 1014 n/cm2 per year) during the 20 years of machine operation. This irradiation may induce changes both on the membranes characteristics (leakage, modification of elasticity) and on gauges which measure their deformations. To investigate these effects and select the transducer to be used in the LHC, a...

  5. Molecular dynamics study of helium bubble pressure in titanium

    Science.gov (United States)

    Zhang, Bao-Ling; Wang, Jun; Hou, Qing

    2011-03-01

    In this paper, the pressure state of the helium bubble in titanium is simulated by a molecular dynamics (MD) method. First, the possible helium/vacancy ratio is determined according to therelation between the bubble pressure and helium/vacancy ratio; then the dependences of the helium bubble pressure on the bubble radius at different temperatures are studied. It is shown that the product of the bubble pressure and the radius is approximately a constant, a result justifying the pressure-radius relation predicted by thermodynamics-based theory for gas bubble. Furthermore, a state equation of the helium bubble is established based on the MD calculations. Comparison between the results obtained by the state equation and corresponding experimental data shows that the state equation can describe reasonably the state of helium bubble and thus could be used for Monte Carlo simulations of the evolution of helium bubble in metals. Project supported by the National Natural Science Foundation of China (Grant No. 10775101) and National Magnetic Confinement Fusion Program of China (Grant No. 2009GB106004).

  6. Experimental Study and Performance Analysis on High-Pressure Stage of Helium Compressor%氦气压气机高压级实验研究及性能分析

    Institute of Scientific and Technical Information of China (English)

    赵洪雷; 来亮; 徐立民; 谭春青

    2012-01-01

      针对高温气冷堆(HTGR)一回路氦气轮机直接发电装置的氦气压气机中,工况最为恶劣的高压级进行性能研究。首先通过实验方法研究了高压级实验叶栅的气动性能,然后采用数值模拟的方法进一步分析其性能,给出了40%~130%设计转速的流量-压比和流量-效率特性曲线,并进行了叶栅内部流动分析。实验研究和数值模拟结果表明,此氦气压气机高压级性能较好,可应用到氦气压气机整机研制中。%  The high-pressure stage performance of helium compressor is studied, which is used in the di⁃rect power generation device with helium turbine in the primary circuit of high temperature gas reactor (HT⁃GR). The operation conditions of high-pressure compressor are the worst in the whole helium compressor. Firstly, aerodynamic performance of the experimental cascade of high-pressure stage was studied by means of experiment method. Then, the high-pressure stage performance was further analyzed through numerical simulation. The characteristic lines of flow rate versus pressure ratio and flow rate versus efficiency were presented from 40% design rotating speed to 130% design rotating speed and the inner flow of cascade was also analyzed. The results of experiment and computation proved that the high-pressure stage has better per⁃formance and can be used to the development of helium compressor.

  7. Extreme ultraviolet spectroscopy of low pressure helium microwave driven discharges

    Science.gov (United States)

    Espinho, Susana; Felizardo, Edgar; Tatarova, Elena; Alves, Luis Lemos

    2016-09-01

    Surface wave driven discharges are reliable plasma sources that can produce high levels of vacuum and extreme ultraviolet radiation (VUV and EUV). The richness of the emission spectrum makes this type of discharge a possible alternative source in EUV/VUV radiation assisted applications. However, due to challenging experimental requirements, publications concerning EUV radiation emitted by microwave plasmas are scarce and a deeper understanding of the main mechanisms governing the emission of radiation in this spectral range is required. To this end, the EUV radiation emitted by helium microwave driven plasmas operating at 2.45 GHz has been studied for low pressure conditions. Spectral lines from excited helium atoms and ions were detected via emission spectroscopy in the EUV/VUV regions. Novel data concerning the spectral lines observed in the 23 - 33 nm wavelength range and their intensity behaviour with variation of the discharge operational conditions are presented. The intensity of all the spectral emissions strongly increases with the microwave power delivered to the plasma up to 400 W. Furthermore, the intensity of all the ion spectral emissions in the EUV range decreases by nearly one order of magnitude as the pressure was raised from 0.2 to 0.5 mbar. Work funded by FCT - Fundacao para a Ciencia e a Tecnologia, under Project UID/FIS/50010/2013 and grant SFRH/BD/52412/2013 (PD-F APPLAuSE).

  8. Parametric study of radiofrequency helium discharge under atmospheric pressure

    Indian Academy of Sciences (India)

    SAFDAR HUSSAIN; HAFIZ IMRAN AHMAD QAZI; SHANAWER NIAZ; MANZOOR AHMAD BADAR

    2016-12-01

    The parameters of radio frequency helium discharge under atmospheric pressure were studied by electrical and optical measurements using high voltage probe, current probe and optical emission spectroscopy. Two discharge modes $\\alpha$ and $\\gamma$ were observed within certain limits. During $\\alpha$ to $\\gamma$ mode transition, a decrease in voltage (280–168 V), current (2.05–1.61 A) and phase angle (76$^{\\rm o}-56^{\\rm o}$) occurred. The discharge parameters such as resistance, reactance, sheath thickness, electron density, excitation temperature and gas temperature were assessed by electrical measurements using equivalent circuit model and optical emission spectroscopy. In $\\alpha$ mode, the discharge current increased from 1.17 to 2.05 A, electron density increased from $0.19 \\times 10^{12} {\\rm to} 0.47 \\times 10^{12} {\\rm cm}^{−3}$ while sheath thickness decreased from 0.40 to 0.25 mm. The excitation temperatures in the $\\alpha$ and $\\gamma$ modes were 3266 and 4500 K respectively, evaluated by Boltzmann’s plot method. The estimated gas temperature increased from 335 K in the α mode to 485 K in the γ mode, suggesting that the radio frequency atmospheric pressure helium discharge can be used for surface treatment applications.

  9. An investigation of high fractions of metastable helium atoms

    Institute of Scientific and Technical Information of China (English)

    X.P.Feng(冯贤平); B.W.James

    2003-01-01

    Penning type discharge was adopted to excite helium atoms. It is suitable for generating high densitymetastables at a range from 0.1 mTorr to 0.5 Tort. The highest metastable density of 3.5 × 1010 cm-3was observed at a static gas pressure of 0.5 Torr. The highest fraction of metastables (N21s/NHe) of 10-3in a low gas pressure was obtained. The variation of the magnetic field strength on the discharge doesnot result in a significant density change of the metastable helium atoms. When no magnetic field wasapplied, no discharge took place.

  10. Exp erimental study on breakdown voltage b etween parallel plates in high-pressure helium%高压氦气平行极板击穿电压实验研究∗

    Institute of Scientific and Technical Information of China (English)

    岳姗; 刘兴男; 时振刚

    2015-01-01

    为获得高温气冷堆核电站电气设备绝缘设计所需基础数据,本文设计了一套测量高压氦气绝缘性能的装置.利用该装置进行了15—20◦C,0.1—7 MPa氦气,间距0.25,0.35,0.5 mm平行极板击穿实验.实验表明:氦气的绝缘性能远低于空气;气压越高,氦气的击穿电压越大,3.0 MPa氦气的击穿电压与常压空气基本一致;根据低气压实验数据和巴申定律推导的公式,在高气压下计算值偏大,且偏差随着气压和间距乘积的增大不断增大;提出了可计算0.1—7 MPa氦气击穿电压的简易公式,同时修正了高气压氦气的巴申公式,并进行了理论分析.%To obtain the base data for insulation design of the electrical equipment used in the high temperature gas cooled reactor nuclear power plant, an experimental apparatus for testing helium insulation property under high pressure is designed. The apparatus is composed of a pressure vessel, a heating system, an electrical penetration assembly, a vacuum pump, a pressure gauge, a safety pressure valve, a release valve, and a helium bottle. The highest pressure that the vessel can hold is 10 MPa, and in this experiment the safety pressure valve is set to be 8 MPa. The temperature inside the vessel can be heated to 200 ◦C by a heating system. The resolution of the pressure gauge is 1 kPa, and the highest pressure that the gauge can measure is 9.999 MPa. The purity of the helium used in this experiment is 99.999%. The breakdown voltage of helium gas between two parallel plane electrodes is measured by the apparatus under the conditions of 15–20 ◦C and 0.1–7 MPa. The electrodes are made of copper, and their diameters are both 100 mm. The distances between the parallel electrodes are 0.25 mm, 0.35 mm and 0.5 mm respectively. The error of the distance is less than 0.01 mm. The DC voltage between the electrodes is supplied by GPI-735A, a withstand voltage and insulation tester produced by GW Instek

  11. The Thermodynamical Instability Induced by Pressure Ionization in Fluid Helium

    CERN Document Server

    Li, Qiong; Zhang, Gong-Mu; Zhao, Yan-Hong; Lu, Guo; Tian, Ming-Feng; Song, Hai-Feng

    2016-01-01

    A systematic study of pressure ionization is carried out in the chemical picture by the example of fluid helium. By comparing the variants of the chemical model, it is demonstrated that the behavior of pressure ionization depends on the construction of the free energy function. In the chemical model with the Coulomb free energy described by the Pad\\'e interpolation formula, thermodynamical instability induced by pressure ionization is found to be manifested by a discontinuous drop or a continuous fall and rise along the pressure-density curve as well as the pressure-temperature curve, which is very much like the first order liquid-liquid phase transition of fluid hydrogen from the first principles simulations. In contrast, in the variant chemical model with the Coulomb free energy term empirically weakened, no thermodynamical instability is induced when pressure ionization occurs, and the resulting equation of state achieves good agreement with the first principles simulations of fluid helium.

  12. Modes of Homogeneous Barrier Discharge at Atmospheric Pressure in Helium

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Hui; WANG De-Zhen

    2004-01-01

    @@ The discharge modes of a homogeneous barrier discharge at atmospheric pressure in helium are investigated with a one-dimensional fluid model It is found that, either in single peak discharge or in multipeak discharge, there are two discharge modes: glow and Townsend modes. The structure and features of the two modes are compared.The conditions forming the two modes are discussed.

  13. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Nastuta, Andrei Vasile; Topala, Ionut; Pohoata, Valentin; Popa, Gheorghe [Faculty of Physics, Alexandru Ioan Cuza University, Bd. Carol No. 11, 700506, Iasi (Romania); Grigoras, Constantin, E-mail: andrei.nastuta@uaic.ro [Physiopathology Department, Grigore T. Popa University of Medicine and Pharmacy, 700115, Iasi (Romania)

    2011-03-16

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  14. Stimulation of wound healing by helium atmospheric pressure plasma treatment

    Science.gov (United States)

    Vasile Nastuta, Andrei; Topala, Ionut; Grigoras, Constantin; Pohoata, Valentin; Popa, Gheorghe

    2011-03-01

    New experiments using atmospheric pressure plasma have found large application in treatment of living cells or tissues, wound healing, cancerous cell apoptosis, blood coagulation on wounds, bone tissue modification, sterilization and decontamination. In this study an atmospheric pressure plasma jet generated using a cylindrical dielectric-barrier discharge was applied for treatment of burned wounds on Wistar rats' skin. The low temperature plasma jet works in helium and is driven by high voltage pulses. Oxygen and nitrogen based impurities are identified in the jet by emission spectroscopy. This paper analyses the natural epithelization of the rats' skin wounds and two methods of assisted epithelization, a classical one using polyurethane wound dressing and a new one using daily atmospheric pressure plasma treatment of wounds. Systemic and local medical data, such as haematological, biochemical and histological parameters, were monitored during entire period of study. Increased oxidative stress was observed for plasma treated wound. This result can be related to the presence in the plasma volume of active species, such as O and OH radicals. Both methods, wound dressing and plasma-assisted epithelization, provided positive medical results related to the recovery process of burned wounds. The dynamics of the skin regeneration process was modified: the epidermis re-epitelization was accelerated, while the recovery of superficial dermis was slowed down.

  15. Electrical heater for very-low pressure helium gas

    CERN Document Server

    Benda, V; Vuillierme, B

    1996-01-01

    Testing superconducting magnets for the Large Hadron Collider (LHC) in superfluid helium requires large-capacity refrigeration at 1.8K. At CERN, this is provided by a combination of a cold compressor and a set of warm vacuum pumps capable of handling up to 18g/s at 1 kPa suction pressure. The cold helium vapour, after the cold compressor, is warmed up from about 5K to ambient temperature in a 32 kW electrical heater. The device is designed to operate reliably at flow rates varying from 1 to 18g/s, inlet pressure of 1 kPa to 3 kPa, with pressure drop 100 Pa. Design and construction of the heater, completely realised at CERN, are presented, as well as measured performance. Some technological problems are discussed.

  16. Design and Test of a Liquid Oxygen / Liquid Methane Thruster with Cold Helium Pressurization Heat Exchanger

    Science.gov (United States)

    Melcher, John C.; Morehead, Robert L.; Atwell, Matthew J.; Hurlbert, Eric A.

    2015-01-01

    A liquid oxygen / liquid methane 2,000 lbf thruster was designed and tested in conjuction with a nozzle heat exchanger for cold helium pressurization. Cold helium pressurization systems offer significant spacecraft vehicle dry mass savings since the pressurant tank size can be reduced as the pressurant density is increased. A heat exchanger can be incorporated into the main engine design to provide expansion of the pressurant supply to the propellant tanks. In order to study the systems integration of a cold-helium pressurization system, a 2,000 lbf thruster with a nozzle heat exchanger was designed for integration into the Project Morpheus vehicle at NASA Johnson Space Center. The testing goals were to demonstrate helium loading and initial conditioning to low temperatures, high-pressure/low temperature storage, expansion through the main engine heat exchanger, and propellant tank injection/pressurization. The helium pressurant tank was an existing 19 inch diameter composite-overwrap tank, and the targert conditions were 4500 psi and -250 F, providing a 2:1 density advantage compared to room tempatrue storage. The thruster design uses like-on-like doublets in the injector pattern largely based on Project Morpheus main engine hertiage data, and the combustion chamber was designed for an ablative chamber. The heat exchanger was installed at the ablative nozzle exit plane. Stand-alone engine testing was conducted at NASA Stennis Space Center, including copper heat-sink chambers and highly-instrumented spoolpieces in order to study engine performance, stability, and wall heat flux. A one-dimensional thermal model of the integrated system was completed. System integration into the Project Morpheus vehicle is complete, and systems demonstrations will follow.

  17. Compression of single-crystal magnesium oxide to 118 GPa and a ruby pressure gauge for helium pressure media

    Science.gov (United States)

    Jacobsen, S. D.; Holl, C. M.; Adams, K. A.; Fischer, R. A.; Martin, E. S.; Bina, C. R.; Lin, J.; Prakapenka, V. B.; Kubo, A.; Dera, P.

    2008-12-01

    Magnesium oxide (MgO, periclase) is among the most widely studied standard materials for testing experimental and theoretical methods of determining elastic properties. Because of its simple structure and geophysical relevance, knowledge of accurate elastic properties of MgO pertains to problems ranging from experimental pressure scales to interpreting Earth's seismic structure. The pressure-volume equation of state (EoS) of single-crystal MgO has been studied in diamond-anvil cells loaded with helium to 118 GPa and in a non-hydrostatic KCl pressure medium to 87 GPa using monochromatic synchrotron X-ray diffraction at GSECARS (Sector 13, APS). A third-order Birch-Murnaghan fit to the non-hydrostatic P-V data (KCl medium) yields typical results for the initial volume, V0=74.698(7)Å3, bulk modulus, KT0=164(1)GPa, and pressure derivative, K'=4.05(4) using the non-hydrostatic ruby pressure gauge of Mao et al. (1978). However, compression of MgO in helium yields V0=74.697(6)Å3, KT0=159.6(6)GPa, and K'=3.74(3) using the quasi-hydrostatic ruby gauge of Mao et al. (1986). In helium, the fitted equation of state of MgO underdetermines the pressure by 8% at 100 GPa when compared with the primary MgO pressure scale of Zha et al. (2000), with KT0=160.2GPa and K'=4.03. The results suggest that either the compression mechanism of MgO changes above 40 GPa (in helium), or the ruby pressure gauge requires adjustment for the softer helium pressure medium. We provide a revised ruby pressure gauge for helium pressure media against the primary MgO pressure scale, which will be useful for future high-pressure crystallographic studies of minerals compressed with helium in the 25-140 GPa range of the lower mantle.

  18. Simulation of low temperature atmospheric pressure corona discharge in helium

    Science.gov (United States)

    Bekasov, Vladimir; Kirsanov, Gennady; Eliseev, Stepan; Kudryavtsev, Anatoly; Sisoev, Sergey

    2015-11-01

    The main objective of this work was to construct a numerical model of corona discharge in helium at atmospheric pressure. The calculation was based on the two-dimensional hybrid model. Two different plasma-chemical models were considered. Models were built for RF corona and negative DC corona discharge. The system of equations is solved by the finite element method in the COMSOL Multiphysics. Main parameters of the discharge (the density of charged and excited particles, the electron temperature) and their dependence on the input parameters of the model (geometry, electrode voltage, power) were calculated. The calculations showed that the shape of the electron distribution near the electrode depends on the discharge power. The neutral gas heating data obtained will allow predicting the temperature of the gases at the designing of atmospheric pressure helium plasma sources.

  19. Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

    Science.gov (United States)

    Wu, Shikai; Xiao, Rongshi

    2015-04-01

    The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage-current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage-current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser-helium arc and YAG laser-arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.

  20. An advanced regulator for the helium pressurization systems of the Space Shuttle OMS and RCS

    Science.gov (United States)

    Wichmann, H.

    1973-01-01

    The Space Shuttle Orbit Maneuvering System and Reaction Control System are pressure-fed rocket propulsion systems utilizing earth storable hypergolic propellants and featuring engines of 6000 lbs and 900 lbs thrust, respectively. The helium pressurization system requirements for these propulsion systems are defined and the current baseline pressurization systems are described. An advanced helium pressure regulator capable of meeting both OMS and RCS helium pressurization system requirements is presented and its operating characteristics and predicted performance characteristics are discussed.

  1. Quality Testing of Gaseous Helium Pressure Vessels by Acoustic Emission

    CERN Document Server

    Barranco-Luque, M; Hervé, C; Margaroli, C; Sergo, V

    1998-01-01

    The resistance of pressure equipment is currently tested, before commissioning or at periodic maintenance, by means of normal pressure tests. Defects occurring inside materials during the execution of these tests or not seen by usual non-destructive techniques can remain as undetected potential sources of failure . The acoustic emission (AE) technique can detect and monitor the evolution of such failures. Industrial-size helium cryogenic systems employ cryogens often stored in gaseous form under pressure at ambient temperature. Standard initial and periodic pressure testing imposes operational constraints which other complementary testing methods, such as AE, could significantly alleviate. Recent reception testing of 250 m3 GHe storage vessels with a design pressure of 2.2 MPa for the LEP and LHC cryogenic systems has implemented AE with the above-mentioned aims.

  2. Genetic effects of radio-frequency, atmospheric-pressure glow discharges with helium

    Science.gov (United States)

    Li, Guo; Li, He-Ping; Wang, Li-Yan; Wang, Sen; Zhao, Hong-Xin; Sun, Wen-Ting; Xing, Xin-Hui; Bao, Cheng-Yu

    2008-06-01

    Due to low gas temperatures and high densities of active species, atmospheric-pressure glow discharges (APGDs) would have potential applications in the fields of plasma-based sterilization, gene mutation, etc. In this letter, the genetic effects of helium radio-frequency APGD plasmas with the plasmid DNA and oligonucleotide as the treated biomaterials are presented. The experimental results show that it is the chemically active species, instead of heat, ultraviolet radiation, intense electric field, and/or charged particles, that break the double chains of the plasmid DNA. The genetic effects depend on the plasma operating parameters, e.g., power input, helium flow rate, processing distance, time, etc.

  3. Microwave capillary plasmas in helium at atmospheric pressure

    Science.gov (United States)

    Santos, M.; Noël, C.; Belmonte, T.; Alves, L. L.

    2014-07-01

    This work uses both simulations and experiments to study helium plasmas (99.999% purity), sustained by surface-wave discharges (2.45 GHz frequency) in capillary tubes (3 mm in-radius) at atmospheric pressure. The simulations use a self-consistent homogeneous and stationary collisional-radiative model (CRM) that solves the rate balance equations for the different species present in the plasma (electrons, He+ and He_2^+ ions, He(n ⩽ 6) excited states and He_2^* excimers) and the gas thermal balance equation, coupled with the two-term electron Boltzmann equation (including direct and stepwise inelastic and superelastic collisions as well as electron-electron collisions). The experiments use optical emission spectroscopy diagnostics to measure the electron density ne (from the Hβ Stark broadening), the gas temperature Tg (from the ro-vibrational transitions of OH, present at trace concentrations) and the populations of excited states in the energy region 22.7-24.2 eV, whose spectrum allows determining the excitation temperature Texc. Measurements yield ne ≃ (2.45 ± 1.4) × 1013 cm-3, Tg ≃ 1700 ± 100 K and Texc ≃ 2793 ± 116 K, for a ˜180 ± 10 W power coupled and ˜1 cm length plasma column. The model predictions at ne = 1.7 × 1013 cm-3 are in very good agreement with measurements yielding Tg = 1800 K, Texc = 2792 K (for ˜30% average relative error between calculated and measured excited-state densities), and a power absorbed by the plasma per unit length of 165 W cm-1. The model results depend strongly on ne, and hence on the plasma conductivity and on the power coupled to the plasma. The coupling of a thermal module to the CRM has been shown to be crucial. Increasing the electron density leads to very high gas temperature values, which limits the variation range of (ne, Tg) as input parameters to the model.

  4. Effects of discharge current and voltage on the high density of metastable helium atoms

    Institute of Scientific and Technical Information of China (English)

    FengXian-Ping; DAndruczyk; BWJames; KTakiyama; SNamba; TOda

    2003-01-01

    Both hollow-cathode and Penning-type discharges were adopted toexcite helium atoms to a metastable state. Experimental data indicate that Penning discharge is more suitable for generating high fractions of metastables in a low-density helium hean for laser-induced fluorescence technique in measuring electric fields at the edge of a plasma. The metastable density increases with increasing helium gas pressure in the range of 1.33×10-2-66.7Pa. The highest metastable density of 3.8×1016m-3 is observed at a static gas pressure of 66.7Pa. An approximately linear relationship between the density of metastable helium atoms and the plasma discharge current is observed. Magnetic field plays a very important role in producing a high density of metastable atoms in Penning discharge.

  5. Effects of discharge current and voltage on the high density of metastable helium atoms

    Institute of Scientific and Technical Information of China (English)

    Feng Xian-Ping(冯贤平); D Andruczyk; B W James; K Takiyama; S Namba; T Oda

    2003-01-01

    Both hollow-cathode and Penning-type discharges were adopted to excite helium atoms to a metastable state.Experimental data indicate that Penning discharge is more suitable for generating high fractions of metastables in a low-density helium beam for laser-induced fluorescence technique in measuring electric fields at the edge of a plasma.The metastable density increases with increasing helium gas pressure in the range of 1.33× 10-2-66.7Pa. The highest metastable density of 3.8 × 1016m-3 is observed at a static gas pressure of 66.7Pa. An approximately linear relationship between the density of metastable helium atoms and the plasma discharge current is observed. Magnetic field plays a very important role in producing a high density of metastable atoms in Penning discharge.

  6. Simplified Methodology to Estimate the Maximum Liquid Helium (LHe) Cryostat Pressure from a Vacuum Jacket Failure

    Science.gov (United States)

    Ungar, Eugene K.; Richards, W. Lance

    2015-01-01

    tool, final verification of the dewar pressure vessel design requires a complete, detailed real fluid compressible flow model of the vent stack. The wall heat flux resulting from a loss of vacuum insulation increases the dewar pressure, which actuates the pressure relief mechanism and results in high-speed flow through the dewar vent stack. At high pressures, the flow can be choked at the vent stack inlet, at the exit, or at an intermediate transition or restriction. During previous SOFIA analyses, it was observed that there was generally a readily identifiable section of the vent stack that would limit the flow – e.g., a small diameter entrance or an orifice. It was also found that when the supercritical helium was approximated as an ideal gas at the dewar condition, the calculated mass flow rate based on choking at the limiting entrance or transition was less than the mass flow rate calculated using the detailed real fluid model2. Using this lower mass flow rate would yield a conservative prediction of the dewar’s wall heat flux capability. The simplified method of the current work was developed by building on this observation.

  7. Helium-3 and Helium-4 acceleration by high power laser pulses for hadron therapy

    CERN Document Server

    Bulanov, S S; Schroeder, C B; Leemans, W P; Bulanov, S V; Margarone, D; Korn, G; Haberer, T

    2015-01-01

    The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (Magnetic Vortex Acceleration and hole-boring Radiation Pressure Acceleration) of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He3 ions, having almost the same penetration depth as He4 with the ...

  8. Helium-3 and helium-4 acceleration by high power laser pulses for hadron therapy

    Directory of Open Access Journals (Sweden)

    S. S. Bulanov

    2015-06-01

    Full Text Available The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions (heavier than protons. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (magnetic vortex acceleration and hole-boring radiation pressure acceleration of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He^{3} ions, having almost the same penetration depth as He^{4} with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

  9. High-Range Scalar Helium Magnetometer (HSHM) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I proposal describes development of a conceptual design for a High-range Scalar Helium Magnetometer (HSHM) for the field range +/-16 Gauss. The HSHM...

  10. High resolution spectroscopy of six new extreme helium stars

    Science.gov (United States)

    Heber, U.; Jones, G.; Drilling, J. S.

    1986-01-01

    High resolution spectra of six newly discovered extreme helium stars are presented. LSS 5121 is shown to be a spectroscopical twin of the hot extreme helium star HD 160641. A preliminary LTE analysis of LSS 3184 yielded an effective temperature of 22,000 K and a surface gravity of log g = 3.2. Four stars form a new subgroup, classified by sharp-lined He I spectra and pronounced O II spectra, and it is conjectured that these lie close to the Eddington limit. The whole group of extreme helium stars apparently is inhomogeneous with respect to luminosity to mass ratio and chemical composition.

  11. Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements

    Science.gov (United States)

    Flesch, K.; Kremeyer, T.; Schmitz, O.; Soukhanovskii, V.; Wenzel, U.

    2016-11-01

    Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D2 molecules and the He ash which will be produced by deuterium-tritium fusion. To study He exhaust, an in situ Penning gauge system is being developed at UW-Madison that is optimized for good pressure and high spectroscopic sensitivity. Three different anode geometries have been studied regarding their vacuum electrostatic fields, light output, and ion current. The light output of the two new anode configurations are at least one order of magnitude above the currently available designs, hence improving the spectroscopic sensitivity at similar total neutral pressure resolution.

  12. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... Surgery? A Week of Healthy Breakfasts Shyness Hypertension (High Blood Pressure) KidsHealth > For Teens > Hypertension (High Blood Pressure) Print ... rest temperature diet emotions posture medicines Why Is High Blood Pressure Bad? High blood pressure means a person's heart ...

  13. CFD Modeling of Helium Pressurant Effects on Cryogenic Tank Pressure Rise Rates in Normal Gravity

    Science.gov (United States)

    Grayson, Gary; Lopez, Alfredo; Chandler, Frank; Hastings, Leon; Hedayat, Ali; Brethour, James

    2007-01-01

    A recently developed computational fluid dynamics modeling capability for cryogenic tanks is used to simulate both self-pressurization from external heating and also depressurization from thermodynamic vent operation. Axisymmetric models using a modified version of the commercially available FLOW-3D software are used to simulate actual physical tests. The models assume an incompressible liquid phase with density that is a function of temperature only. A fully compressible formulation is used for the ullage gas mixture that contains both condensable vapor and a noncondensable gas component. The tests, conducted at the NASA Marshall Space Flight Center, include both liquid hydrogen and nitrogen in tanks with ullage gas mixtures of each liquid's vapor and helium. Pressure and temperature predictions from the model are compared to sensor measurements from the tests and a good agreement is achieved. This further establishes the accuracy of the developed FLOW-3D based modeling approach for cryogenic systems.

  14. Thermodynamic Vent System Performance Testing with Subcooled Liquid Methane and Gaseous Helium Pressurant

    Science.gov (United States)

    Flachbart, R. H.; Hastings, L. J.; Hedayat, A.; Nelson, S. L.; Tucker, S. P.

    2007-01-01

    Due to its high specific impulse and favorable thermal properties for storage, liquid methane (LCH4) is being considered as a candidate propellant for exploration architectures. In order to gain an -understanding of any unique considerations involving micro-gravity pressure control with LCH4, testing was conducted at the Marshall Space Flight Center using the Multipurpose Hydrogen Test Bed (MHTB) to evaluate the performance of a spray-bar thermodynamic vent system (TVS) with subcooled LCH4 and gaseous helium (GHe) pressurant. Thirteen days of testing were performed in November 2006, with total tank heat leak conditions of about 715 W and 420 W at a fill level of approximately 90%. The TVS system was used to subcool the LCH4 to a liquid saturation pressure of approximately 55.2 kPa before the tank was pressurized with GHe to a total pressure of 165.5 kPa. A total of 23 TVS cycles were completed. The TVS successfully controlled the ullage pressure within a prescribed control band but did not maintain a stable liquid saturation pressure. This was likely. due to a TVS design not optimized for this particular propellant and test conditions, and possibly due to a large artificially induced heat input directly into the liquid. The capability to reduce liquid saturation pressure as well as maintain it within a prescribed control band, demonstrated that the TVS could be used to seek and maintain a desired liquid inlet temperature for an engine (at a cost of propellant lost through the TVS vent). One special test was conducted at the conclusion of the planned test activities. Reduction of the tank ullage pressure by opening the Joule-Thomson valve (JT) without operating the pump was attempted. The JT remained open for over 9300 seconds, resulting in an ullage pressure reduction of 30 kPa. The special test demonstrated the feasibility of using the JT valve for limited ullage pressure reduction in the event of a pump failure.

  15. Start-up phase of the HELOKA-LP low pressure helium test facility for IFMIF irradiation modules

    Energy Technology Data Exchange (ETDEWEB)

    Schlindwein, Georg, E-mail: georg.schlindwein@kit.edu [Institute for Neutron Physics and Reactor Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Arbeiter, Frederik; Freund, Jana [Institute for Neutron Physics and Reactor Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Helium Loop Karlsruhe-Low Pressure (HELOKA-LP) succesfully taken to operation at the end of 2009. Black-Right-Pointing-Pointer Verified that HELOKA-LP fulfils all requirements to test the High Flux Test Module (HFTM). Black-Right-Pointing-Pointer Some improvements could be done (e.g. reduction of power consumption, enhancement of control path parameters). Black-Right-Pointing-Pointer We obtained a chronological sequence of the helium gas impurity which is important for the International Fusion Irradiation Facility (IFMIF). - Abstract: As part of the Engineering Validation and Engineering Design Activities (EVEDA) for the International Fusion Materials Irradiation Facility (IFMIF) , it is foreseen to design and test a 1:1 scale prototype of the IFMIF High Flux Test Module (HFTM) . The module has been designed to be cooled by a low pressure helium gas flowing through minichannels to remove the nuclear heat. The Helium Loop Karlsruhe-Low Pressure (HELOKA-LP) has been designed to provide coolant at 1:1 HFTM operational conditions: massflow 12-120 g/s, inlet pressure 0.3-0.6 MPa, inlet temperature RT - 250 Degree-Sign C. A secondary objective is to use the experience gained with HELOKA-LP for the planning of the IFMIF helium cooling system. The facility has been put into operation in 2009, and has since then been in a test and optimization phase. It was proven, that the above mentioned requirements for the facility are achieved. The paper describes the process layout and components of the facility. The performance is characterized by the results of several steady state and transient benchmark tests. Typical start-up and transition times relevant for the operation mode in the IFMIF irradiation campaigns are obtained. Additionally first results on the impurity ingress and the cooling gas chemistry are described.

  16. Electrical Properties for Capacitively Coupled Radio Frequency Discharges of Helium and Neon at Low Pressure

    Science.gov (United States)

    Tanisli, Murat; Sahin, Neslihan; Demir, Suleyman

    2016-10-01

    In this study, the symmetric radio frequency (RF) electrode discharge is formed between the two electrodes placing symmetric parallel. The electrical properties of symmetric capacitive RF discharge of pure neon and pure helium have been obtained from current and voltage waveforms. Calculations are done according to the homogeneous discharge model of capacitively coupled radio frequency (CCRF) using with the data in detail. Electrical properties of bulk plasma and sheath capacitance are also investigated at low pressure with this model. This study compares the electrical characteristics and sheath capacitance changes with RF power and pressure for helium and neon discharges. Also, the aim of the study is to see the differences between helium and neon discharges' current and voltage values. Their root-mean-square voltages and currents are obtained from Tektronix 3052C oscilloscope. Modified homogeneous discharge model of CCRF is used for low pressure discharges and the calculations are done using experimental results. It is seen that homogeneous discharge model of CCRF is usable with modification and then helium and neon discharge's electrical properties are investigated and presented with a comparison. Helium discharge's voltage and current characteristic have smaller values than neon's. It may be said that neon discharge is a better conductor than helium discharge. It is seen that the sheath capacitance is inversely correlation with sheath resistance.

  17. High-precision spectroscopy of antiprotonic helium

    CERN Document Server

    Widmann, E

    2001-01-01

    We present first results of laser and microwave spectroscopy experiments of antiprotonic helium performed at the new Antiproton Decelerator (AD) at CERN. Extending a series of previous measurements done at the Low Energy Antiproton Ring (LEAR) of CERN, several laser- induced transitions of the antiproton in the exotic three-body system He/sup 2+/-e/sup -/-p could be determined with a precision down to 1.3*10/sup -7/. This constitutes an improvement of a factor 3 over previous measurements, and allows to test accurate three-body calculations of this system that include QED corrections. The observed agreement on the same level can be used to infer CPT limits on the antiproton charge and mass. Furthermore, a first indication of a resonance signal of a two-laser microwave triple experiment to measure the hyperfine splitting of antiprotonic helium could been observed. Such a measurement has the potential to determine the antiproton magnetic moment to a higher precision that it is known today. (19 refs).

  18. Thermodynamic analysis of helium boil-off experiments with pressure variations

    Science.gov (United States)

    Cha, Y. S.; Niemann, R. C.; Hull, J. R.

    A thermodynamic analysis by calorimetric experiments in a system with changing pressure is presented. A general equation is derived for use in calculating the rate of heat loss from measured mass flow rate. The results show that the largest contribution from pressure variation is the sensible heat of liquid helium in a Dewar. A dimensionless parameter that was identified provides an indication of the importance of pressure variation relative to the latent heat of vaporization during an experiment. This dimensionless parameter is a function of system pressure land the thermodynamic properties of helium), rate of change of system pressure, liquid helium inventory in the Dewar and measured mass flow rate. In the special case when the effect of pressure variation is small compared to the latent heat of vaporization, the heat loss rate is the product of the measured mass flow rate and the latent heat of vaporization, multiplied by a correction factor that is a function of the ratio of vapour density to liquid density. This correction factor is significant for helium at pressures near or above 1 atm and should always be included in the calculation.

  19. Hydraulic testing of helium cooled irradiation rigs of the IFMIF High Flux Test Module

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Christine, E-mail: Christine.Klein@kit.edu [Karlsruhe Institute of Technology, INR, Eggenstein-Leopoldshafen (Germany); Arbeiter, Frederik; Jackowski, Thomas; Martin, Thomas; Schlindwein, Georg [Karlsruhe Institute of Technology, INR, Eggenstein-Leopoldshafen (Germany)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Uniform perfusion of the multiple parallel minichannels of the rig model B by helium gas, which is of importance to obtain uniform and predictable temperatures, could be verified by measuring the mean velocity profiles of the rectangular jets are measured using hot-wire anemometry. Black-Right-Pointing-Pointer The pressure drop in the test section with rig model B was measured and delivers data for the validation of computational fluid dynamics (CFD) modeling approach for application in the IFMIF High Flux Test Module. The pressure drop depends significantly on the pressure level; acceleration resulting from the volumetric expansion of helium gas has to be modeled carefully in simulations. Black-Right-Pointing-Pointer Measurements with strain gage show the pressure depending deformation of the compartment container without the rig. The results agree well with simulations and approximation calculations. - Abstract: The hydraulic testing of a single 1:1 irradiation rig inside a mock-up container is part of the validation activities which support the engineering design of the High Flux Test Module. Uniform perfusion of the multiple parallel minichannels of the irradiation rigs by helium gas is of importance to obtain uniform and predictable temperatures. To evaluate the uniform distribution to the different parallel minichannels, the mean velocity profiles of the rectangular jets are measured using hot-wire anemometry. The velocity profiles show a symmetric and constant distribution of the mass flow to the parallel minichannels. The pressure drop in the test section with one of the candidate rig shapes is measured. The pressure drop depends significantly on the entrance pressure level; acceleration resulting from the volumetric expansion of helium gas has to be taken into account in simulations. Measurements with strain gage show the pressure depending deformation of the compartment container without the rig. The results agree

  20. Electric field development in γ-mode radiofrequency atmospheric pressure glow discharge in helium

    Science.gov (United States)

    Navrátil, Zdeněk; Josepson, Raavo; Cvetanović, Nikola; Obradović, Bratislav; Dvořák, Pavel

    2016-06-01

    Time development of electric field strength during radio-frequency sheath formation was measured using Stark polarization spectroscopy in a helium γ-mode radio-frequency (RF, 13.56 MHz) atmospheric pressure glow discharge at high current density (3 A cm-2). A method of time-correlated single photon counting was applied to record the temporal development of spectral profile of He I 492.2 nm line with a sub-nanosecond temporal resolution. By fitting the measured profile of the line with a combination of pseudo-Voigt profiles for forbidden (2 1P-4 1F) and allowed (2 1P-4 1D) helium lines, instantaneous electric fields up to 32 kV cm-1 were measured in the RF sheath. The measured electric field is in agreement with the spatially averaged value of 40 kV cm-1 estimated from homogeneous charge density RF sheath model. The observed rectangular waveform of the electric field time development is attributed to increased sheath conductivity by the strong electron avalanches occurring in the γ-mode sheath at high current densities.

  1. Nanocrystalline silicon prepared at high growth rate using helium dilution

    Indian Academy of Sciences (India)

    Koyel Bhattacharya; Debajyoti Das

    2008-06-01

    Growth and optimization of the nanocrystalline silicon (nc-Si : H) films have been studied by varying the electrical power applied to the helium diluted silane plasma in RF glow discharge. Wide optical gap and conducting intrinsic nanocrystalline silicon network of controlled crystalline volume fraction and oriented crystallographic lattice planes have been obtained at a reasonably high growth rate from helium diluted silane plasma, without using hydrogen. Improving crystallinity in the network comprising ∼ 10 nm Si-nanocrystallites and contributing optical gap widening, conductivity ascending and that obtained during simultaneous escalation of the deposition rate, promises significant technological impact.

  2. High Blood Pressure

    Science.gov (United States)

    ... normal blood pressure 140/90 or higher is high blood pressure Between 120 and 139 for the top number, ... prehypertension. Prehypertension means you may end up with high blood pressure, unless you take steps to prevent it. High ...

  3. High Blood Pressure (Hypertension)

    Science.gov (United States)

    ... Print Page Text Size: A A A Listen High Blood Pressure (Hypertension) Nearly 1 in 3 American adults has ... weight. How Will I Know if I Have High Blood Pressure? High blood pressure is a silent problem — you ...

  4. Empirical Models of Pressure and Density in Saturn's Interior: Implications for the Helium Concentration, its Depth Dependence, and Saturn's Precession Rate

    CERN Document Server

    Helled, Ravit; Anderson, John D

    2008-01-01

    We present 'empirical' models (pressure vs. density) of Saturn's interior constrained by the gravitational coefficients J_2, J_4, and J_6 for different assumed rotation rates of the planet. The empirical pressure-density profile is interpreted in terms of a hydrogen and helium physical equation of state to deduce the hydrogen to helium ratio in Saturn and to constrain the depth dependence of helium and heavy element abundances. The planet's internal structure (pressure vs. density) and composition are found to be insensitive to the assumed rotation rate for periods between 10h:32m:35s and 10h:41m:35s. We find that helium is depleted in the upper envelope, while in the high pressure region (P >~ 1 Mbar) either the helium abundance or the concentration of heavier elements is significantly enhanced. Taking the ratio of hydrogen to helium in Saturn to be solar, we find that the maximum mass of heavy elements in Saturn's interior ranges from ~ 6 to 20 M_Earth. The empirical models of Saturn's interior yield a mome...

  5. Discharge Characteristics in Atmospheric Pressure Glow Surface Discharge in Helium Gas

    Institute of Scientific and Technical Information of China (English)

    LI Xue-Chen; WANG Long

    2005-01-01

    @@ Atmospheric pressure glow discharge is observed for the first time in a surface discharge generator in flowing helium. Electrical and optical methods are used to measure the characteristics of atmospheric pressure glow discharge for different voltages. The results show that discharge current waveforms are asymmetric for the different polarities of the applied voltage. A continuous discharge profile with a width of several microseconds appears for per half cycle of the applied voltage when the voltage is increased to a certain value. The short-pulsed discharge and the continuous current would result from the Townsend breakdown and glow discharge mechanisms respectively. The properties of surface discharge in stagnant helium are completely different from that in flowing helium.

  6. Numerical Investigation of Thermal Distribution and Pressurization Behavior in Helium Pressurized Cryogenic Tank by Introducing a Multi-component Model

    Science.gov (United States)

    Lei, Wang; Yanzhong, Li; Zhan, Liu; Kang, Zhu

    An improved CFD model involving a multi-component gas mixturein the ullage is constructed to predict the pressurization behavior of a cryogenic tank considering the existence of pressurizing helium.A temperature difference between the local fluid and its saturation temperature corresponding to the vapor partial pressure is taken as the phase change driving force. As practical application of the model, hydrogen and oxygen tanks with helium pressurization arenumerically simulated by using themulti-component gas model. The results presentthat the improved model produce higher ullage temperature and pressure and lower wall temperaturethan those without multi-component consideration. The phase change has a slight influence on thepressurization performance due to the small quantities involved.

  7. Dynamics of liquid helium boil-off experiments with a step change in pressure

    Science.gov (United States)

    Cha, Y. S.; Niemann, R. C.; Hull, J. R.

    The results of dynamic analysis of the effect of pressure variations during helium boil-off experiments are presented. A general solution of the diffusion equation with a time-dependent boundary condition is employed to describe the dynamic response of the liquid helium system under variable pressure conditions, and a solution is obtained for the special case when the system is subjected to a step change in pressure. The calculated temperature response of the liquid indicates that most of the experiments were not likely to have reached equilibrium as a result of the low thermal diffusivity of liquid helium. The initial rate of evaporation or condensation is large, and the rate decreases sharply with time. A method is proposed to account for the transient effect that is observed during calculation of the heat loss rate from a helium boil-off experiment. By assuming that there is no mixing at all, the present analysis provides an estimate of the upper (condensation) or lower (evaporation) bound of the heat loss rate as a result of a pressure increase or decrease in the system. A previously reported equilibrium analysis is expected to apply to situations where complete mixing occurred in the bulk liquid and provides the opposite limits.

  8. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... Loss Surgery? A Week of Healthy Breakfasts Shyness Hypertension (High Blood Pressure) KidsHealth > For Teens > Hypertension (High Blood Pressure) A ... rest temperature diet emotions posture medicines Why Is High Blood Pressure Bad? High blood pressure means a person's heart ...

  9. High pressure technology 1994

    Energy Technology Data Exchange (ETDEWEB)

    Kapp, J.A.; Picqueuer, L.M. (eds.)

    1994-01-01

    This volume is divided into four sessions: fracture mechanics applications to high pressure vessels; high pressure code issues; high pressure design, analysis, and safety concerns; and military and other high pressure applications. Separate abstracts were prepared for eleven papers of this conference.

  10. Development of a high vacuum sample preparation system for helium mass spectrometer

    Science.gov (United States)

    Kumar, P.; Das, N. K.; Mallik, C.; Bhandari, R. K.

    2012-11-01

    A high vacuum sample preparation system for the 3He/4He ratio mass spectrometer (Helix SFT) has been developed to remove all the gaseous constituents excluding helium from the field gases. The sample preparation system comprises of turbo molecular pump, ion pump, zirconium getter, pipettes and vacuum gauges with controller. All these are fitted with cylindrical SS chamber using all metal valves. The field samples are initially treated with activated charcoal trap immersed in liquid nitrogen to cutoff major impurities and moisture present in the sample gas. A sample of 5 ml is collected out of this stage at a pressure of 10-2 mbar. This sample is subsequently purified at a reduced pressure of 10-7 mbar before it is injected into the ion source of the mass spectrometer. The sample pressure was maintained below 10-7 mbar with turbo molecular vacuum pumps and ion pumps. The sample gas passes through several getter elements and a cold finger with the help of manual high vacuum valves before it is fed to the mass spectrometer. Thus the high vacuum sample preparation system introduces completely clean, dry and refined helium sample to the mass spectrometer for best possible analysis of isotopic ratio of helium.

  11. Investigation of the threshold intensity versus gas pressure in the breakdown of helium by 248 nm laser radiation

    Science.gov (United States)

    Gamal, Yosr E. E.-D.; Abdellatif, Galila

    2014-10-01

    An investigation of the unexpectedly strong dependence of the threshold intensity on the gas pressure in the experimental study on the breakdown of He by short laser wavelength (Turcu et al., in Opt Commun, 134:66-68, 1997) is presented. A modified electron cascade model is applied (Evans and Gamal, in J Phys D Appl Phys, 13:1447-1458, 1980). Computations revealed reasonable agreement between the calculated thresholds and the measured ones. Moreover, the calculated electron energy distribution function and its parameters proved that multiphoton ionization of ground and excited atoms is the main source for the seed electrons, which contributes to the breakdown of helium. The effect of diffusion losses over pressures <1,000 Torr elucidated the origin of the strong dependence of the threshold intensity on the gas pressure. Collisional ionization dominates only at high pressures. No evidence for recombination losses is observed for pressures up to 3,000 Torr.

  12. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Norberg, Seth A., E-mail: norbergs@umich.edu; Johnsen, Eric, E-mail: ejohnsen@umich.edu [Department of Mechanical Engineering, University of Michigan, 2350 Hayward Street, Ann Arbor, Michigan 48109-2125 (United States); Kushner, Mark J., E-mail: mjkush@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109-2122 (United States)

    2015-07-07

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O{sub 2} = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  13. Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Changwon (Korea, Republic of)

    2016-09-15

    An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.

  14. A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor

    CERN Document Server

    Bonneton, M; Gistau-Baguer, Guy M; Turcat, F; Viennot, P

    1998-01-01

    A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new specific technology are described. Particular attention is paid to the gas bearing supported rotor and to the pneumatic driver. Trade off between existing technologies and the present work are presented with special stress on the bearing system and the driver. The advantages are discussed, essentially focused on life time and high reliability without maintenance as well as non pollution characteristic. Practical operational modes are also described together with the experimental performances of the compressor. The article concludes with a brief outlook of future work.

  15. Comparison of nitrogen narcosis and helium pressure effects on striatal amino acids: a microdialysis study in rats.

    Science.gov (United States)

    Vallée, Nicolas; Rostain, Jean-Claude; Boussuges, Alain; Risso, Jean-Jacques

    2009-05-01

    Exposure to nitrogen-oxygen mixture at high pressure induces narcosis, which can be considered as a first step toward general anaesthesia. Narcotic potencies of inert gases are attributed to their lipid solubility. Nitrogen narcosis induces cognitive and motor disturbances that occur from 0.3 MPa in man and from 1 MPa in rats. Neurochemical studies performed in rats up to 3 MPa have shown that nitrogen pressure decreases striatal dopamine release like argon, another inert gas, or nitrous oxide, an anaesthetic gas. Striatal dopamine release is under glutamatergic and other amino acid neurotransmission regulations. The aim of this work was to study the effects of nitrogen at 3 MPa on striatal amino acid levels and to compare to those of 3 MPa of helium which is not narcotic at this pressure, by using a new technique of microdialysis samples extraction under hyperbaric conditions, in freely moving rats. Amino acids were analysed by HPLC coupled to fluorimetric detection in order to appreciate glutamate, aspartate, glutamine and asparagine levels. Nitrogen-oxygen mixture exposure at 3 MPa decreased glutamate, glutamine and asparagine concentrations. In contrast, with helium-oxygen mixture, glutamate and aspartate levels were increased during the compression phase but not during the stay at maximal pressure. Comparison between nitrogen and helium highlighted the narcotic effects of nitrogen at pressure. As a matter of fact, nitrogen induces a reduction in glutamate and in other amino acids that could partly explain the decrease in striatal dopamine level as well as the motor and cognitive disturbances reported in nitrogen narcosis.

  16. High blood pressure medications

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007484.htm High blood pressure medicines To use the sharing features on this page, please enable JavaScript. Treating high blood pressure will help prevent problems such as heart disease, ...

  17. Use of Interrupted Helium Flow in the Analysis of Vapor Samples with Flowing Atmospheric-Pressure Afterglow-Mass Spectrometry

    Science.gov (United States)

    Storey, Andrew P.; Zeiri, Offer M.; Ray, Steven J.; Hieftje, Gary M.

    2017-02-01

    The flowing atmospheric-pressure afterglow (FAPA) source was used for the mass-spectrometric analysis of vapor samples introduced between the source and mass spectrometer inlet. Through interrupted operation of the plasma-supporting helium flow, helium consumption is greatly reduced and dynamic gas behavior occurs that was characterized by schlieren imaging. Moreover, mass spectra acquired immediately after the onset of helium flow exhibit a signal spike before declining and ultimately reaching a steady level. This initial signal appears to be due to greater interaction of sample vapor with the afterglow of the source when helium flow resumes. In part, the initial spike in signal can be attributed to a pooling of analyte vapor in the absence of helium flow from the source. Time-resolved schlieren imaging of the helium flow during on and off cycles provided insight into gas-flow patterns between the FAPA source and the MS inlet that were correlated with mass-spectral data.

  18. A critical review of liquid helium temperature high frequency pulse tube cryocoolers for space applications

    Science.gov (United States)

    Wang, B.; Gan, Z. H.

    2013-08-01

    The importance of liquid helium temperature cooling technology in the aerospace field is discussed, and the results indicate that improving the efficiency of liquid helium cooling technologies, especially the liquid helium high frequency pulse tube cryocoolers, is the principal difficulty to be solved. The state of the art and recent developments of liquid helium high frequency pulse tube cryocoolers are summarized. The main scientific challenges for high frequency pulse tube cryocoolers to efficiently reach liquid helium temperatures are outlined, and the research progress addressing those challenges are reviewed. Additionally some possible solutions to the challenges are pointed out and discussed.

  19. DC high voltage to drive helium plasma jet comprised of repetitive streamer breakdowns

    CERN Document Server

    Wang, Xingxing

    2016-01-01

    This paper demonstrates and studies helium atmospheric pressure plasma jet comprised of series of repetitive streamer breakdowns, which is driven by a pure DC high voltage (auto-oscillations). Repetition frequency of the breakdowns is governed by the geometry of discharge electrodes/surroundings and gas flow rate. Each next streamer is initiated when the electric field on the anode tip recovers after the previous breakdown and reaches the breakdown threshold value of about 2.5 kV/cm. Repetition frequency of the streamer breakdowns excited using this principle can be simply tuned by reconfiguring the discharge electrode geometry. This custom-designed type of the helium plasma jet, which operates on the DC high voltage and is comprised of the series of the repetitive streamer breakdowns at frequency about 13 kHz, is demonstrated.

  20. Treating High Blood Pressure

    Science.gov (United States)

    About High Blood Pressure Many people in the United States die from high blood pressure. This condition usually does not cause symptoms. Most ... until it is too late. A person has high blood pressure when the blood pushes against Visit your doctor ...

  1. High blood pressure - children

    Science.gov (United States)

    ... number is the diastolic pressure. This measures the pressure in the arteries when the heart is at rest. Blood pressure ... Medical Professional Call your child's provider if home monitoring shows that your child's blood pressure is still high. Prevention Your child's provider will ...

  2. Innovative Method for Developing a Helium Pressurant Tank Suitable for the Upper Stage Flight Experiment

    Science.gov (United States)

    DeLay, Tom K.; Munafo, Paul (Technical Monitor)

    2001-01-01

    The AFRL USFE project is an experimental test bed for new propulsion technologies. It will utilize ambient temperature fuel and oxidizers (Kerosene and Hydrogen peroxide). The system is pressure fed, not pump fed, and will utilize a helium pressurant tank to drive the system. Mr. DeLay has developed a method for cost effectively producing a unique, large pressurant tank that is not commercially available. The pressure vessel is a layered composite structure with an electroformed metallic permeation barrier. The design/process is scalable and easily adaptable to different configurations with minimal cost in tooling development 1/3 scale tanks have already been fabricated and are scheduled for testing. The full-scale pressure vessel (50" diameter) design will be refined based on the performance of the sub-scale tank. The pressure vessels have been designed to operate at 6,000 psi. a PV/W of 1.92 million is anticipated.

  3. High-pressure apparatus

    NARCIS (Netherlands)

    Schepdael, van L.J.M.; Bartels, P.V.; Berg, van den R.W.

    1999-01-01

    The invention relates to a high-pressure device (1) having a cylindrical high-pressure vessel (3) and prestressing means in order to exert an axial pressure on the vessel. The vessel (3) can have been formed from a number of layers of composite material, such as glass, carbon or aramide fibers which

  4. Use of Heated Helium to Simulate Surface Pressure Fluctuations on the Launch Abort Vehicle During Abort Motor Firing

    Science.gov (United States)

    Panda, Jayanta; James, George H.; Burnside, Nathan J.; Fong, Robert; Fogt, Vincent A.

    2011-01-01

    The solid-rocket plumes from the Abort motor of the Multi-Purpose Crew Vehicle (MPCV, also know as Orion) were simulated using hot, high pressure, Helium gas to determine the surface pressure fluctuations on the vehicle in the event of an abort. About 80 different abort situations over a wide Mach number range, (0.3abort case, typically two different Helium plume and wind tunnel conditions were used to bracket different flow matching critera. This unique, yet cost-effective test used a custom-built hot Helium delivery system, and a 6% scale model of a part of the MPCV, known as the Launch Abort Vehicle. The test confirmed the very high level of pressure fluctuations on the surface of the vehicle expected during an abort. In general, the fluctuations were found to be dominated by the very near-field hydrodynamic fluctuations present in the plume shear-layer. The plumes were found to grow in size for aborts occurring at higher flight Mach number and altitude conditions. This led to an increase in the extent of impingement on the vehicle surfaces; however, unlike some initial expectations, the general trend was a decrease in the level of pressure fluctuations with increasing impingement. In general, the highest levels of fluctuations were found when the outer edges of the plume shear layers grazed the vehicle surface. At non-zero vehicle attitudes the surface pressure distributions were found to become very asymmetric. The data from these wind-tunnel simulations were compared against data collected from the recent Pad Abort 1 flight test. In spite of various differences between the transient flight situation and the steady-state wind tunnel simulations, the hot-Helium data were found to replicate the PA1 data fairly reasonably. The data gathered from this one-of-a-kind wind-tunnel test fills a gap in the manned-space programs, and will be used to establish the acoustic environment for vibro-acoustic qualification testing of the MPCV.

  5. Simulation of the mantle and crustal helium isotope signature in the Mediterranean Sea using a high-resolution regional circulation model

    Science.gov (United States)

    Ayache, M.; Dutay, J.-C.; Jean-Baptiste, P.; Fourré, E.

    2015-12-01

    Helium isotopes (3He, 4He) are useful tracers for investigating the deep ocean circulation and for evaluating ocean general circulation models, because helium is a stable and conservative nuclide that does not take part in any chemical or biological process. Helium in the ocean originates from three different sources, namely, (i) gas dissolution in equilibrium with atmospheric helium, (ii) helium-3 addition by radioactive decay of tritium (called tritiugenic helium), and (iii) injection of terrigenic helium-3 and helium-4 by the submarine volcanic activity which occurs mainly at plate boundaries, and also addition of (mainly) helium-4 from the crust and sedimentary cover by α-decay of uranium and thorium contained in various minerals. We present the first simulation of the terrigenic helium isotope distribution in the whole Mediterranean Sea using a high-resolution model (NEMO-MED12). For this simulation we build a simple source function for terrigenic helium isotopes based on published estimates of terrestrial helium fluxes. We estimate a hydrothermal flux of 3.5 mol3 He yr-1 and a lower limit for the crustal flux at 1.6 × 10-7 4He mol m-2 yr-1. In addition to providing constraints on helium isotope degassing fluxes in the Mediterranean, our simulations provide information on the ventilation of the deep Mediterranean waters which is useful for assessing NEMO-MED12 performance. This study is part of the work carried out to assess the robustness of the NEMO-MED12 model, which will be used to study the evolution of the climate and its effect on the biogeochemical cycles in the Mediterranean Sea, and to improve our ability to predict the future evolution of the Mediterranean Sea under the increasing anthropogenic pressure.

  6. Numerical Modeling and Test Data Comparison of Propulsion Test Article Helium Pressurization System

    Science.gov (United States)

    Holt, Kimberly; Majumdar, Alok; Steadman, Todd; Hedayat, Ali; Fogle, Frank R. (Technical Monitor)

    2000-01-01

    A transient model of the propulsion test article (PTA) helium pressurization system was developed using the generalized fluid system simulation program (GFSSP). The model included pressurization lines from the facility interface to the engine purge interface and liquid oxygen (lox) and rocket propellant-1 (RP-1) tanks, the propellant tanks themselves including ullage space, and propellant feed lines to their respective pump interfaces. GFSSP's capability was extended to model a control valve to maintain ullage pressure within a specified limit and pressurization processes such as heat transfer between ullage gas, propellant, and the tank wall as well as conduction in the tank wall. The purpose of the model is to predict the flow system characteristics in the entire pressurization system during 80 sec of lower feed system priming, 420 sec of fuel and lox pump priming, and 150 sec of engine firing.

  7. Electron heating and particle fluxes in dual frequency atmospheric-pressure helium capacitive discharge

    Science.gov (United States)

    Liu, Dingxin; Yang, Aijun; Wang, Xiaohua; Chen, Chen; Rong, Mingzhe; Kong, Michael G.

    2016-12-01

    In this letter, a 1D fluid model has been used to study the electron heating and particle transport in dual frequency atmospheric-pressure helium capacitive discharge with a high-frequency (HF) voltage of 10 MHz and a low-frequency (LF) voltage of 1 MHz. The electric field is decoupled to three components: the HF, the LF and the direct current (DC) ones, and they have much different effects on the plasmas. The eletrons in plasma bulk are mainly heated by the HF electric field, while in plasma sheath they are heated and cooled by the LF and DC electric fields, respectively. With a fixed total input power, the increase of LF power leads to great enhancement of the electrode fluxes of electrons and ions, especially for the energetic electrons of T e  >  2 eV, because more power is dissipated in the vicinity of electrodes and the inelastic collision is more pronounced. Therefore, the particle transport on the treated sample can be greatly enhanced without additional gas heating in dual frequency plasmas, which meets the application requirements more compared to the single frequency plasmas.

  8. Benchmarking density functionals for hydrogen-helium mixtures with quantum Monte Carlo: Energetics, pressures, and forces

    Science.gov (United States)

    Clay, Raymond C.; Holzmann, Markus; Ceperley, David M.; Morales, Miguel A.

    2016-01-01

    An accurate understanding of the phase diagram of dense hydrogen and helium mixtures is a crucial component in the construction of accurate models of Jupiter, Saturn, and Jovian extrasolar planets. Though density-functional-theory-based first-principles methods have the potential to provide the accuracy and computational efficiency required for this task, recent benchmarking in hydrogen has shown that achieving this accuracy requires a judicious choice of functional, and a quantification of the errors introduced. In this work, we present a quantum Monte Carlo (QMC) -based benchmarking study of a wide range of density functionals for use in hydrogen-helium mixtures at thermodynamic conditions relevant for Jovian planets. Not only do we continue our program of benchmarking energetics and pressures, but we deploy QMC-based force estimators and use them to gain insight into how well the local liquid structure is captured by different density functionals. We find that TPSS, BLYP, and vdW-DF are the most accurate functionals by most metrics, and that the enthalpy, energy, and pressure errors are very well behaved as a function of helium concentration. Beyond this, we highlight and analyze the major error trends and relative differences exhibited by the major classes of functionals, and we estimate the magnitudes of these effects when possible.

  9. High resolution helium ion scanning microscopy of the rat kidney.

    Science.gov (United States)

    Rice, William L; Van Hoek, Alfred N; Păunescu, Teodor G; Huynh, Chuong; Goetze, Bernhard; Singh, Bipin; Scipioni, Larry; Stern, Lewis A; Brown, Dennis

    2013-01-01

    Helium ion scanning microscopy is a novel imaging technology with the potential to provide sub-nanometer resolution images of uncoated biological tissues. So far, however, it has been used mainly in materials science applications. Here, we took advantage of helium ion microscopy to explore the epithelium of the rat kidney with unsurpassed image quality and detail. In addition, we evaluated different tissue preparation methods for their ability to preserve tissue architecture. We found that high contrast, high resolution imaging of the renal tubule surface is possible with a relatively simple processing procedure that consists of transcardial perfusion with aldehyde fixatives, vibratome tissue sectioning, tissue dehydration with graded methanol solutions and careful critical point drying. Coupled with the helium ion system, fine details such as membrane texture and membranous nanoprojections on the glomerular podocytes were visualized, and pores within the filtration slit diaphragm could be seen in much greater detail than in previous scanning EM studies. In the collecting duct, the extensive and striking apical microplicae of the intercalated cells were imaged without the shrunken or distorted appearance that is typical with conventional sample processing and scanning electron microscopy. Membrane depressions visible on principal cells suggest possible endo- or exocytotic events, and central cilia on these cells were imaged with remarkable preservation and clarity. We also demonstrate the use of colloidal gold probes for highlighting specific cell-surface proteins and find that 15 nm gold labels are practical and easily distinguishable, indicating that external labels of various sizes can be used to detect multiple targets in the same tissue. We conclude that this technology represents a technical breakthrough in imaging the topographical ultrastructure of animal tissues. Its use in future studies should allow the study of fine cellular details and provide

  10. High Blood Pressure Facts

    Science.gov (United States)

    ... More black women than men have high blood pressure. 2 Race of Ethnic Group Men (%) Women (%) African Americans 43.0 45.7 Mexican Americans 27.8 28.9 Whites 33.9 31.3 All 34.1 32.7 Top of Page Why Blood Pressure Matters View this graphic snapshot of blood pressure ...

  11. High capacity 30 K remote helium cooling loop

    Science.gov (United States)

    Trollier, T.; Tanchon, J.; Icart, Y.; Ravex, A.

    2014-01-01

    Absolut System has built several 50 K remote helium cooling loops used as high capacity and very low vibration cooling source into large wavelength IR detectors electro-optical characterization test benches. MgB2 based superconducting electro-technical equipment's under development require also distributed high cooling power in the 20-30 K temperature range. Absolut System has designed, manufactured and tested a high capacity 30 K remote helium cooling loop. The equipment consists of a CRYOMECH AL325 type cooler, a CP830 type compressor package used as room temperature circulator and an intermediate LN2 bath cooling used between two recuperator heat exchangers (300 K-77 K and 77 K-20 K). A cooling capacity of 30 W @ 20 K or 80 W @ 30 K has been demonstrated on the application heat exchanger, with a 4-meter remote distance ensured by a specifically designed gas circulation flexible line. The design and the performance will be reported in this paper.

  12. Simulation of Oxygen Disintegration and Mixing With Hydrogen or Helium at Supercritical Pressure

    Science.gov (United States)

    Bellan, Josette; Taskinoglu, Ezgi

    2012-01-01

    The simulation of high-pressure turbulent flows, where the pressure, p, is larger than the critical value, p(sub c), for the species under consideration, is relevant to a wide array of propulsion systems, e.g. gas turbine, diesel, and liquid rocket engines. Most turbulence models, however, have been developed for atmospheric-p turbulent flows. The difference between atmospheric-p and supercritical-p turbulence is that, in the former situation, the coupling between dynamics and thermodynamics is moderate to negligible, but for the latter it is very significant, and can dominate the flow characteristics. The reason for this stems from the mathematical form of the equation of state (EOS), which is the perfect-gas EOS in the former case, and the real-gas EOS in the latter case. For flows at supercritical pressure, p, the large eddy simulation (LES) equations consist of the differential conservation equations coupled with a real-gas EOS. The equations use transport properties that depend on the thermodynamic variables. Compared to previous LES models, the differential equations contain not only the subgrid scale (SGS) fluxes, but also new SGS terms, each denoted as a correction. These additional terms, typically assumed null for atmospheric pressure flows, stem from filtering the differential governing equations, and represent differences between a filtered term and the same term computed as a function of the filtered flow field. In particular, the energy equation contains a heat-flux correction (q-correction) that is the difference between the filtered divergence of the heat flux and the divergence of the heat flux computed as a function of the filtered flow field. In a previous study, there was only partial success in modeling the q-correction term, but in this innovation, success has been achieved by using a different modeling approach. This analysis, based on a temporal mixing layer Direct Numerical Simulation database, shows that the focus in modeling the q

  13. Numerical study of the interaction of a helium atmospheric pressure plasma jet with a dielectric material

    Science.gov (United States)

    Wang, Lijun; Zheng, Yashuang; Jia, Shenli

    2016-10-01

    This is a computational modeling study of a cold atmospheric pressure helium plasma jet impinging on a dielectric surface placed normal to the jet axis. This study provides insights into the propagation mechanism of the plasma jet, the electrical properties, and the total accumulated charge density at the dielectric surface. For the radial streamer propagation along the dielectric surface, Penning ionization and the electron impact ionization of helium atoms are the major ionization reactions in the streamer head, while Penning ionization is the only dominant contributor along the streamer body. In addition, the plasma bullet velocity along the dielectric surface is 10-100 times lower than that in the plasma column. Increasing tube radius or helium flow rate lowers air entrainment in the plasma jet, leading to a decrease of the radial electric field and the accumulated charge density at the dielectric surface. Furthermore, the tube radius has weaker influence on the plasma properties as tube radius increases. For a target dielectric with lower relative permittivity, a higher radial electric field penetrates into the material, and the surface ionization wave along the dielectric surface extends farther. Higher relative permittivity of the treated dielectric results in more charging at the dielectric surface and more electron density in the plasma column.

  14. Equation of state and interaction potential of helium under high temperatures and high densities

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on the thermodynamics statistic method, the improved variational perturbation theory and the modified quantum mechanics correction model have been used to calculate the equation of state of liquid helium at pressure from 0.7 to 108 GPa. The calculation results are in good agreement with the experimental data. The EXP-6 potential (α = 13.1) can more accurately describe the interaction of helium atoms than other potentials in the scheme. Finally, a comparison is shown between our interatomic potentials and other potentials.

  15. Equation of state and interaction potential of helium under high temperatures and high densities

    Institute of Scientific and Technical Information of China (English)

    YANG JinWen; YAN YuanHong

    2009-01-01

    Based on the thermodynamics statistic method, the improved variational perturbation theory and the modified quantum mechanics correction model have been used to calculate the equation of state of liquid helium at pressure from 0.7 to 108 GPa. The calculation results are in good agreement with the experimental data. The EXP-6 potential (α=13.1) can more accurately describe the interaction of helium atoms than other potentials in the scheme. Finally, s comparison is shown between our interatomic potentials and other potentials.

  16. Optical properties of the atmospheric pressure helium plasma jet generated by alternative current (a.c.) power supply

    Science.gov (United States)

    Ilik, Erkan; Akan, Tamer

    2016-05-01

    In this work, an atmospheric pressure plasma jet (APPJ) was produced to generate cold flowing post-discharge plasma of pure helium gas. The main aim of this study was to generate cold flowing APPJ of pure helium gas and to determine how their optical emission spectrum change influences varying different flow rates. Lengths of early, middle, and late post-discharge plasma (jet) regions and their fluctuations were determined, respectively. Then, ignition condition dependence of the post-discharge plasma for flow rate was specified at a constant voltage. Spectroscopic studies of an atmospheric pressure plasma jet of helium were presented via analyzing OH, N2, N2+, oxygen, and helium intensities for various flow rates.

  17. Coherent scattering of $\\pi$ mesons from helium at high energies : 4 papers

    CERN Document Server

    Ekelöf, T J C

    1972-01-01

    [Article I: A measurement of the differential cross section for elastic pion-helium scattering at 7.76 GeV/c] Results are presented for the region of squared four-momentum transfers between −0.05 and −0.5 (GeV/c)2. The directions of the scattered pions and alpha particles were measured with spark chambers and the momentum of the alphas as obtained from pulse-height and time-of-flight measurements. The results are compared with calculations from the Glauber theory, showing good agreement over the whole momentum-transfer range including the interference-dip region. [Article II:A helium-recoil spectrometer] The instrument described is intended for the detection and measurement of particles from coherent interactions of high-energy particles with 4He nuclei. It allows the determination of the magnitude and the direction of the momenta of the helium recoils from interactions in a pressurized gas target. The measurements are carried out with spark chambers and scintillation counters. Recoils emitted at angles g...

  18. Numerical Simulations of Pressure Spikes within a Cylindrical Launch Tube due to a Bursting Helium Flask

    Science.gov (United States)

    2011-11-09

    Above 50 atm pressure, the system deviates from ideal gas law behavior as shown by the red curve. This curve was obtained using the Cheetah 6.0...equation of state for Helium6 and calculating 1 1 2 2PV PV directly from the 8 Harold D. Ladouceur and Benjamin Gould Cheetah output. Note...that the Cheetah code utilizes the ideal gas law to calculate A as indicated by the black dots in Figure 6. A key point of this figure is the

  19. Radial Evolution of the Atmospheric Pressure Glow Discharge in Helium Controlled by Dielectric Barrier

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuan-Tao; WANG De-Zhen; WANG Yan-Hui; LIU Cheng-Sen

    2005-01-01

    @@ The radial evolution of atmospheric pressure glow discharge in helium is presented by numerical simulation. The calculations reveal the mechanism of two current peaks per half cycle. The first breakdown occurs firstly in the central region of the electrode, and then spreads to the edge, while the second breakdown ignites at the periphery firstly, and then propagates toward the discharge central region. The simulations indicate that radial electric fields and radial sheath play an important role in the evolution of the second peak. These results agree fundamentally with the experimental observations.

  20. Production of stable, non-thermal atmospheric pressure rf capacitive plasmas using gases other than helium or neon

    Science.gov (United States)

    Park, Jaeyoung; Henins, Ivars

    2005-06-21

    The present invention enables the production of stable, steady state, non-thermal atmospheric pressure rf capacitive .alpha.-mode plasmas using gases other than helium and neon. In particular, the current invention generates and maintains stable, steady-state, non-thermal atmospheric pressure rf .alpha.-mode plasmas using pure argon or argon with reactive gas mixtures, pure oxygen or air. By replacing rare and expensive helium with more readily available gases, this invention makes it more economical to use atmospheric pressure rf .alpha.-mode plasmas for various materials processing applications.

  1. High blood pressure - infants

    Science.gov (United States)

    ... Certain tumors Inherited conditions (problems that run in families) Thyroid problems Blood pressure rises as the baby grows. The average blood ... vomiting constantly Prevention Some causes of high blood pressure run in families. Talk to your provider before you get pregnant ...

  2. Preventing High Blood Pressure

    Science.gov (United States)

    ... Web Sites Division for Heart Disease and Stroke Prevention Stroke Heart Disease Cholesterol Salt Million Hearts® WISEWOMAN Preventing High Blood Pressure: Healthy Living Habits Recommend on Facebook Tweet Share Compartir By living a healthy lifestyle, you can help keep your blood pressure in ...

  3. Influence of voltage magnitude on the dynamic behavior of a stable helium atmospheric pressure plasma jet

    Science.gov (United States)

    Ning, Wenjun; Wang, Lijun; Wu, Chen; Jia, Shenli

    2014-08-01

    Effects of voltage magnitude on the development of a stable helium atmospheric pressure plasma jet are investigated by current measurements and high temporal-resolution streak images. Generated by a coaxial dielectric barrier discharge structure, the entire discharge can be classified into three regions: discharges in the tube gap, downstream jet, and up-streamer. The discharge morphologies of each region are analyzed. In the positive discharge phase, there are two discharges in the tube gap between the electrodes; the first one is ignited as corona and then developed into streamer corona, and the second one is similar with positive glow. The downstream jet is ignited independently from the discharge in the tube gap. Referred as "plasma bullet," the dynamic behavior of the jet can be well described as a positive streamer. Under specific applied voltage, the jet is found to be composed by double bullets in which case the jet length decreases since that less charge is carried by the first bullet. The up-streamer can be captured as long as the discharge in the tube gap is activated. Propagating with velocity of ˜4 km/s, the up-streamer can be regarded as the extension of the first discharge in the tube gap. In the negative discharge phase, the discharge is confined in the tube gap with nearly symmetrical morphology with the positive one. Besides, with the rising of voltage, the negative discharge is initially intensified and then turns weaker after surpassing certain voltage, which may provide suitable condition for the occurrence of double-bullet phenomenon.

  4. High Blood Pressure (Hypertension)

    Science.gov (United States)

    ... already been diagnosed with high blood pressure. Try yoga and meditation. Yoga and meditation not only can strengthen your body ... Accessed Sept. 21, 2015. Hu B, et al. Effects of psychological stress on hypertension in middle-aged ...

  5. Liquid Hydrogen Propellant Tank Sub-Surface Pressurization with Gaseous Helium

    Science.gov (United States)

    Stephens, J. R.; Cartagena, W.

    2015-01-01

    A series of tests were conducted to evaluate the performance of a propellant tank pressurization system with the pressurant diffuser intentionally submerged beneath the surface of the liquid. Propellant tanks and pressurization systems are typically designed with the diffuser positioned to apply pressurant gas directly into the tank ullage space when the liquid propellant is settled. Space vehicles, and potentially propellant depots, may need to conduct tank pressurization operations in micro-gravity environments where the exact location of the liquid relative to the diffuser is not well understood. If the diffuser is positioned to supply pressurant gas directly to the tank ullage space when the propellant is settled, then it may become partially or completely submerged when the liquid becomes unsettled in a microgravity environment. In such case, the pressurization system performance will be adversely affected requiring additional pressurant mass and longer pressurization times. This series of tests compares and evaluates pressurization system performance using the conventional method of supplying pressurant gas directly to the propellant tank ullage, and then supplying pressurant gas beneath the liquid surface. The pressurization tests were conducted on the Engineering Development Unit (EDU) located at Test Stand 300 at NASA Marshall Space Flight Center (MSFC). EDU is a ground based Cryogenic Fluid Management (CFM) test article supported by Glenn Research Center (GRC) and MSFC. A 150 ft3 propellant tank was filled with liquid hydrogen (LH2). The pressurization system used regulated ambient helium (GHe) as a pressurant, a variable position valve to maintain flow rate, and two identical independent pressurant diffusers. The ullage diffuser was located in the forward end of the tank and was completely exposed to the tank ullage. The submerged diffuser was located in the aft end of the tank and was completely submerged when the tank liquid level was 10% or greater

  6. Equation of state of fluid helium at high temperatures and densities

    Institute of Scientific and Technical Information of China (English)

    CAI; Lingcang; CHEN; Qifeng; GU; Yunjun; ZHANG; Ying; ZHOU

    2005-01-01

    Hugoniot curves and shock temperatures of gas helium with initial temperature 293 K and three initial pressures 0.6, 1.2, and 5.0 Mpa were measured up to 15000 K using a two-stage light-gas gun and transient radiation pyrometer. It was found that the calculated Hugoniot EOS of gas helium at the same initial pressure using Saha equation with Debye-Hückel correction was in good agreement with the experimental data. The curve of the calculated shock wave velocity with the particle velocity of gas helium which is shocked from the initial pressure 5 Mpa and temperature 293 K, I.e., the D~u relation, D = C0+λu (u < 10 km/s, λ = 1.32) in a low pressure region, is approximately parallel with the fitted D~u (λ = 1.36) of liquid helium from the experimental data of Nellis et al. Our calculations show that the Hugoniot parameterλis independent of the initial density ρ0. The D~u curves of gas helium will transfer to another one and approach a limiting value of compression when their temperature elevates to about 18000 K and the ionization degree of the shocked gas helium reaches 10-3.

  7. Modeling the dynamic response of pressures in a distributed helium refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, John Carl [Illinois Inst. of Technology, Chicago, IL (United States)

    1997-12-01

    A mathematical model is created of the dynamic response of pressures caused by flow inputs to an existing distributed helium refrigeration system. The dynamic system studied consists of the suction and discharge pressure headers and compressor portions of the refrigeration system used to cool the superconducting magnets of the Tevatron accelerator at the Fermi National Accelerator Laboratory. The modeling method involves identifying the system from data recorded during a series of controlled tests, with effort made to detect locational differences in pressure response around the four mile accelerator circumference. A review of the fluid mechanics associated with the system indicates linear time invariant models are suitable for the identification, particularly since the governing equations of one dimensional fluid flow are approximated by linear differential equations. An outline of the experimental design and the data acquisition system are given, followed by a detailed description of the modeling, which utilized the Matlab programming language and associated System Identification Toolbox. Two representations of the system are presented. One, a black box model, provides a multi-input, multi-output description assembled from the results of single input step function testing. This description indicates definite variation in pressure response with distance from the flow input location, and also suggests subtle differences in response with the input location itself. A second system representation is proposed which details the relation between continuous flow changes and pressure response, and provides explanation of a previously unappreciated pressure feedback internal to the system.

  8. The influence of high grain boundary density on helium retention in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Valles, G., E-mail: gonzalovallesalberdi@hotmail.es [Instituto de Fusión Nuclear UPM, José Gutiérrez Abascal 2, 28006 Madrid (Spain); González, C. [Departamento de Física, Universidad de Oviedo, C/ Calvo Sotelo, s/n, Oviedo (Spain); Martin-Bragado, I. [IMDEA Materials Institute, C/ Enric Kandel 2, 28906 Getafe, Madrid (Spain); Iglesias, R. [Departamento de Física, Universidad de Oviedo, C/ Calvo Sotelo, s/n, Oviedo (Spain); Perlado, J.M.; Rivera, A. [Instituto de Fusión Nuclear UPM, José Gutiérrez Abascal 2, 28006 Madrid (Spain)

    2015-02-15

    Highlights: • Comparison between monocrystalline and nanostructured irradiated tungsten. • OKMC parameterization published and new DFT data. • Important role of grain boundary density on defect evolution. • Cluster pressurization much lower in nanostructured tungsten. • Promising expectations on nanocrystalline tungsten in view of results. - Abstract: In order to study the influence of a high grain boundary density on the amount, size and distribution of defects produced by pulsed helium (625 keV) irradiation in tungsten, we have carried out Object Kinetic Monte Carlo (OKMC) simulations in both monocrystalline and nanocrystalline tungsten. The parameterization of the OKMC code (MMonCa) includes binding energies obtained with our in-house Density Functional Theory (DFT) calculations. In the interior of a grain in nanocrystalline tungsten the mixed He{sub n}V{sub m} clusters are larger and have a lower He/V ratio. Thus, they are less pressurized clusters. The total elastic strain energy remains almost constant with the increasing number of pulses, contrary to its increase in monocrystalline tungsten. A better response to helium irradiation is therefore expected in nanocrystalline tungsten, opening a new path to investigate these nanostructured materials for fusion purposes.

  9. Numerical Modeling of Helium Pressurization System of Propulsion Test Article (PTA)

    Science.gov (United States)

    Steadman, Todd; Majumdar, Alok; Holt, Kimberly

    2001-01-01

    A transient model of the Propulsion Test Article (PTA) Helium Pressurization System was developed using the Generalized Fluid System Simulation Program (GFSSP). The model included feed lines from the facility interface to the engine purge interface and Liquid Oxygen (LOX) and Rocket Propellant 1 (RP-1) tanks, the propellant tanks themselves including ullage space and propellant feed lines to their respective pump interfaces. GFSSP's capability was extended to model a control valve to maintain ullage pressure within a specified limit and pressurization processes such as heat transfer between ullage gas, propellant and the tank wall. The purpose of the model is to predict the flow system characteristics in the entire pressurization system during 80 seconds of lower feed system priming, 420 seconds of fuel and LOX pump priming and 150 seconds of engine firing. Subsequent to the work presented here, the PTA model has been updated to include the LOX and RP-1 pumps, while the pressurization option itself has been modified to include the effects of mass transfer. This updated model will be compared with PTA test data as it becomes available.

  10. Similarity and cascade flow characteristics of a highly loaded helium compressor

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Bin, E-mail: jiangbin_hrbeu@163.com [College of Power & Energy Engineering of Harbin Engineering University, Harbin 150001 (China); Chen, Zhongliang [College of Power & Energy Engineering of Harbin Engineering University, Harbin 150001 (China); Chen, Hang [AVIG Shenyang Engine Design and Research Institute, Shenyang 110015 (China); Zhang, Hai; Zheng, Qun [College of Power & Energy Engineering of Harbin Engineering University, Harbin 150001 (China)

    2015-05-15

    Highlights: • The deviation of different similarity criteria is analyzed theoretically. • Flow difference between helium and air compressor cascades is analyzed numerically. • The analysis of calculated results validates the theoretical derivation. • Flow characteristics of highly loaded helium compressor blade profile are computed. - Abstract: Helium compressor is a major component of the Power Conversion Unit (PCU) used in a High Temperature Gas Cooled Reactor (HTGR). Because the high cost of closed cycle test and leakage problem of helium gas, air could be used as working fluid instead of helium in compressor performance tests. However, the properties of Helium are largely different from those of air, e.g. the adiabatic exponent of Helium is 1.6, while the adiabatic exponent itself is a criterion of similarity between the two compressors. The characteristics of compressor will be different due to the effect of the adiabatic exponent of working fluid, especially for highly loaded compressor working at higher inlet Mach number. In this paper, a theoretical study on the similarity between air compressor and a highly loaded helium compressor is carried out and the deviation of similarity is analyzed. Numerical simulations are then used to confirm the theoretical analysis. The results indicate that the similarity deviation could not be neglected for highly loaded compressor cascade, which means the experience and experimental results of those conventional air compressor cannot be applied directly to the design of highly loaded helium compressor. The flow characteristics of a highly loaded helium compressor at different Reynolds numbers, attack angles, Mach numbers and cascade geometries are then investigated.

  11. DC negative corona discharge in atmospheric pressure helium: transition from the corona to the ‘normal’ glow regime

    Science.gov (United States)

    Hasan, Nusair; Antao, Dion S.; Farouk, Bakhtier

    2014-06-01

    Direct current (dc) negative corona discharges in atmospheric pressure helium are simulated via detailed numerical modeling. Simulations are conducted to characterize the discharges in atmospheric helium for a pin plate electrode configuration. A self-consistent two-dimensional hybrid model is developed to simulate the discharges and the model predictions are validated with experimental measurements. The discharge model considered consists of momentum and energy conservation equations for a multi-component (electrons, ions, excited species and neutrals) gas mixture, conservation equations for each component of the mixture and state relations. A drift-diffusion approximation for the electron and the ion fluxes is used. A model for the external circuit driving the discharge is also considered and solved along with the discharge model. Many of the key features of a negative corona discharge, namely non-linear current-voltage characteristics, spatially flat cathode current density and glow-like discharge in the high current regime are displayed in the predictions. A transition to the ‘normal’ glow discharge from the corona discharge regime is also observed. The transition is identified from the calculated current-voltage characteristic curve and is characterized by the radial growth of the negative glow and the engulfment of the cathode wire.

  12. Prevention of High Blood Pressure

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Prevention of High Blood Pressure Healthy lifestyle habits, proper use of medicines, and ... prevent high blood pressure or its complications. Preventing High Blood Pressure Onset Healthy lifestyle habits can help prevent high ...

  13. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    Science.gov (United States)

    Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

    2017-05-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

  14. High Blood Pressure Fact Sheet

    Science.gov (United States)

    ... High Blood Pressure Salt Cholesterol Million Hearts® WISEWOMAN High Blood Pressure Fact Sheet Language: English Español (Spanish) Recommend on ... time. High blood pressure is also called hypertension. High Blood Pressure in the United States Having high blood pressure ...

  15. Simulation of transition from Townsend mode to glow discharge mode in a helium dielectric barrier discharge at atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    Li Xue-Chen; Niu Dong-Ying; Xu Long-Fei; Jia Peng-Ying; Chang Yuan-Yuan

    2012-01-01

    The dielectric barrier discharge characteristics in helium at atmospheric pressure are simulated based on a one-dimensional fluid model.Under some discharge conditions,the results show that one discharge pulse per half voltage cycle usually appears when the amplitude of external voltage is low,while a glow-like discharge occurs at high voltage.For the one discharge pulse per half voltage cycle,the maximum of electron density appears near the anode at the beginning of the discharge,which corresponds to a Townsend discharge mode.The maxima of the electron density and the intensity of electric field appear in the vicinity of the cathode when the discharge current increases to some extent,which indicates the formation of a cathode-fall region.Therefore,the discharge has a transition from the Townsend mode to the glow discharge mode during one discharge pulse,which is consistent with previous experimental results.

  16. Modeling of High-voltage Breakdown in Helium

    Science.gov (United States)

    Xu, Liang; Khrabrov, Alexander; Kaganovich, Igor; Sommerer, Timothy

    2016-09-01

    We investigate the breakdown in extremely high reduced electric fields (E/N) between parallel-plate electrodes in helium. The left branch of the Paschen curve in the voltage range of 20-350kV and inter-electrode gap range of 0.5-3.5cm is studied analytically and with Monte-Carlo/PIC simulations. The model incorporates electron, ion, and fast neutral species whose energy-dependent anisotropic scattering, as well as backscattering at the electrodes, is carefully taken into account. Our model demonstrates that (1) anisotropic scattering is indispensable for producing reliable results at such high voltage and (2) due to the heavy species backscattered at cathode, breakdown can occur even without electron- and ion-induced ionization of the background gas. Fast atoms dominate in the breakdown process more and more as the applied voltage is increased, due to their increasing ionization cross-section and to the copious flux of energetic fast atoms generated in charge-exchange collisions.

  17. Correlation between helium atmospheric pressure plasma jet (APPJ) variables and plasma induced DNA damage

    Science.gov (United States)

    Adhikari, Ek R.; Ptasinska, Sylwia

    2016-09-01

    A helium atmospheric pressure plasma jet (APPJ) source with a dielectric capillary and two tubular electrodes was used to induce damage in aqueous plasmid DNA. The fraction of different types of DNA damage (i.e., intact or undamaged, double strand breaks (DSBs), and single strand breaks (SSBs)) that occurred as the result of plasma irradiation was quantified through analysis of agarose gel electrophoresis images. The total DNA damage increased with an increase in both flow rate and duration of irradiation, but decreased with an increase in distance between the APPJ and sample. The average power of the plasma was calculated and the length of APPJ was measured for various flow rates and voltages applied. The possible effects of plasma power and reactive species on DNA damage are discussed.

  18. Extending helium partial pressure measurement technology to JET DTE2 and ITER

    Science.gov (United States)

    Klepper, C. C.; Biewer, T. M.; Kruezi, U.; Vartanian, S.; Douai, D.; Hillis, D. L.; Marcus, C.

    2016-11-01

    The detection limit for helium (He) partial pressure monitoring via the Penning discharge optical emission diagnostic, mainly used for tokamak divertor effluent gas analysis, is shown here to be possible for He concentrations down to 0.1% in predominantly deuterium effluents. This result from a dedicated laboratory study means that the technique can now be extended to intrinsically (non-injected) He produced as fusion reaction ash in deuterium-tritium experiments. The paper also examines threshold ionization mass spectroscopy as a potential backup to the optical technique, but finds that further development is needed to attain with plasma pulse-relevant response times. Both these studies are presented in the context of continuing development of plasma pulse-resolving, residual gas analysis for the upcoming JET deuterium-tritium campaign (DTE2) and for ITER.

  19. Electron dynamics and plasma jet formation in a helium atmospheric pressure dielectric barrier discharge jet

    Energy Technology Data Exchange (ETDEWEB)

    Algwari, Q. Th. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); Electronic Department, College of Electronics Engineering, Mosul University, Mosul 41002 (Iraq); O' Connell, D. [Centre for Plasma Physics, School of Maths and Physics, Queen' s University Belfast, University Road, Belfast, Northern Ireland BT7 1NN (United Kingdom); York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom)

    2011-09-19

    The excitation dynamics within the main plasma production region and the plasma jets of a kHz atmospheric pressure dielectric barrier discharge (DBD) jet operated in helium was investigated. Within the dielectric tube, the plasma ignites as a streamer-type discharge. Plasma jets are emitted from both the powered and grounded electrode end; their dynamics are compared and contrasted. Ignition of these jets are quite different; the jet emitted from the powered electrode is ignited with a slight time delay to plasma ignition inside the dielectric tube, while breakdown of the jet at the grounded electrode end is from charging of the dielectric and is therefore dependent on plasma production and transport within the dielectric tube. Present streamer theories can explain these dynamics.

  20. Diagnosis of High Blood Pressure

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    Full Text Available ... the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  1. Liquid Hydrogen Regulated Low Pressure High Flow Pneumatic Panel AFT Arrow Analysis

    Science.gov (United States)

    Jones, Kelley, M.

    2013-01-01

    Project Definition: Design a high flow pneumatic regulation panel to be used with helium and hydrogen. The panel will have two circuits, one for gaseous helium (GHe) supplied from the GHe Movable Storage Units (MSUs) and one for gaseous hydrogen (GH2) supplied from an existing GH2 Fill Panel. The helium will supply three legs; to existing panels and on the higher pressure leg and Simulated Flight Tanks (SFTs) for the lower pressure legs. The hydrogen line will pressurize a 33,000 gallon vacuum jacketed vessel.

  2. High Pressure Biomass Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Pradeep K [Georgia Tech Research Corporation, Atlanta, GA (United States)

    2016-07-29

    According to the Billion Ton Report, the U.S. has a large supply of biomass available that can supplement fossil fuels for producing chemicals and transportation fuels. Agricultural waste, forest residue, and energy crops offer potential benefits: renewable feedstock, zero to low CO2 emissions depending on the specific source, and domestic supply availability. Biomass can be converted into chemicals and fuels using one of several approaches: (i) biological platform converts corn into ethanol by using depolymerization of cellulose to form sugars followed by fermentation, (ii) low-temperature pyrolysis to obtain bio-oils which must be treated to reduce oxygen content via HDO hydrodeoxygenation), and (iii) high temperature pyrolysis to produce syngas (CO + H2). This last approach consists of producing syngas using the thermal platform which can be used to produce a variety of chemicals and fuels. The goal of this project was to develop an improved understanding of the gasification of biomass at high pressure conditions and how various gasification parameters might affect the gasification behavior. Since most downstream applications of synags conversion (e.g., alcohol synthesis, Fischer-Tropsch synthesis etc) involve utilizing high pressure catalytic processes, there is an interest in carrying out the biomass gasification at high pressure which can potentially reduce the gasifier size and subsequent downstream cleaning processes. It is traditionally accepted that high pressure should increase the gasification rates (kinetic effect). There is also precedence from coal gasification literature from the 1970s that high pressure gasification would be a beneficial route to consider. Traditional approach of using thermogravimetric analyzer (TGA) or high-pressure themogravimetric analyzer (PTGA) worked well in understanding the gasification kinetics of coal gasification which was useful in designing high pressure coal gasification processes. However

  3. Measurement of O and OH radical produced by an atmospheric-pressure helium plasma jet nearby rat skin

    Science.gov (United States)

    Yonemori, Seiya; Ono, Ryo

    2013-09-01

    Atmospheric-pressure helium plasma jet is getting much attention because it enables many kinds of plasma applications including biomedical application such as sterilization and cancer treatment. In biomedical plasma applications, it is though that active species like ions and radicals play important role. Especially, OH radical and O atom is very chemically reactive that they are deemed as major factors in cancer treatment. In this study, O and OH density distribution and its temporal behavior nearby rat skin were measured to demonstrate actual application. Plasma discharge was under AC10 kVp-p, 10 kHz with 1.5 slm (standard litter per minute) of helium gas flow. OH density was around 1 ppm and O atom density was around 10 ppm at maximum. We also measured time-evolution of OH and O atom density. Both OH and O density was almost constant between discharge pulses because lifetime of active species could be prolonged in helium. And density distribution of both species varied depending on helium flow rate and water concentration on the surface; on rat skin or on the grass surface. Those results suggest the production mechanisms and provision mechanisms of O atom and OH radical by an atmospheric-pressure helium plasma jet. This work is partially supported by the Grant-in-Aid for Science Research by the Ministry of Education, Culture, Sport, Science and Technology.

  4. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet.

    Science.gov (United States)

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T H; Kang, Tae-Hong

    2014-10-16

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment.

  5. Comparative study of high voltage bushing designs suitable for apparatus containing cryogenic helium gas

    Science.gov (United States)

    Rodrigo, H.; Graber, L.; Kwag, D. S.; Crook, D. G.; Trociewitz, B.

    2013-10-01

    The high voltage bushing forms a critical part of any termination on cables, transformers and other power system devices. Cryogenic entities such as superconducting cables or fault current limiters add more complexity to the design of the bushing. Even more complex are bushings designed for superconducting devices which are cooled by high pressure helium gas. When looking for a bushing suitable for dielectric cable tests in a helium gas cryostat no appropriate device could be found that fulfilled the criterion regarding partial discharge inception voltage level. Therefore we decided to design and manufacture a bushing in-house. In the present work we describe the dielectric tests and operational experience on three types of bushings: One was a modified commercially available ceramics feed through which we adopted for our special need. The second bushing was made of an epoxy resin, with an embedded copper squirrel cage arrangement at the flange, extending down about 30 cm into the cold end of the bushing. This feature reduced the electric field on the surface of the bushing to a negligible value. The third bushing was based on a hollow body consisting of glass fiber reinforced polymer and stainless steel filled with liquid nitrogen. The measurements showed that the dielectric quality of all three bushings exceeded the requirements for the intended purpose. The partial discharge (PD) data from these studies will be used for the design and fabrication of a cable termination for a specialized application on board a US Navy ship.

  6. Pulsed Discharge Helium Ionization Detector for Highly Sensitive Aquametry.

    Science.gov (United States)

    Mowry, Curtis D; Pimentel, Adam S; Sparks, Elizabeth S; Moorman, Matthew W; Achyuthan, Komandoor E; Manginell, Ronald P

    2016-01-01

    Trace moisture quantitation is crucial in medical, civilian and military applications. Current aquametry technologies are limited by the sample volume, reactivity, or interferences, and/or instrument size, weight, power, cost, and complexity. We report for the first time on the use of a pulsed discharge helium ionization detector (PDHID-D2) (∼196 cm(3)) for the sensitive (limit of detection, 0.047 ng; 26 ppm), linear (r(2) >0.99), and rapid (volume of liquid or gas. The relative humidity sensitivity was 0.22% (61.4 ppmv) with a limit of detection of less than 1 ng moisture with gaseous samples. The sensitivity was 10 to 100 to fold superior to competing technologies without the disadvantages inherent to these technologies. The PDHID-D2, due to its small footprint and low power requirement, has good size, weight, and power-portability (SWAPP) factors. The relatively low cost (∼$5000) and commercial availability of the PDHID-D2 makes our technique applicable to highly sensitive aquametry.

  7. High-order harmonic conversion efficiency in helium

    Energy Technology Data Exchange (ETDEWEB)

    Crane, J.K.

    1992-10-23

    Calculated results are presented for the energy, number of photons, and conversion efficiency for high-order harmonic generation in helium. The results show the maximum values that we should expect to achieve experimentally with our current apparatus and the important parameters for scaling this source to higher output. In the desired operating regime where the coherence length, given by L{sub coh}={pi}b/(q-1), is greater than the gas column length, l, the harmonic output can be summarized by a single equation: N{sub q}=[({pi}{sup z}n{sup z}b{sup 3}{tau}{sub q}{vert_bar}d{sub q}{vert_bar}{sup z})/4h]{l_brace}(p/q)(2l/b){sup z}{r_brace}. N{sub q} - numbers of photons of q-th harmonic; n - atom density; b - laser confocal parameter; {tau}{sub q} - pulse width of harmonic radiation; q - harmonic order; p - effective order of nonlinearity. (Note the term in brackets, the phase-matching function, has been separated from the rest of the expression in order to be consistent with the relevant literature).

  8. High-order harmonic conversion efficiency in helium

    Energy Technology Data Exchange (ETDEWEB)

    Crane, J.K.

    1992-10-23

    Calculated results are presented for the energy, number of photons, and conversion efficiency for high-order harmonic generation in helium. The results show the maximum values that we should expect to achieve experimentally with our current apparatus and the important parameters for scaling this source to higher output. In the desired operating regime where the coherence length, given by L[sub coh]=[pi]b/(q-1), is greater than the gas column length, l, the harmonic output can be summarized by a single equation: N[sub q]=[([pi][sup z]n[sup z]b[sup 3][tau][sub q][vert bar]d[sub q][vert bar][sup z])/4h][l brace](p/q)(2l/b)[sup z][r brace]. N[sub q] - numbers of photons of q-th harmonic; n - atom density; b - laser confocal parameter; [tau][sub q] - pulse width of harmonic radiation; q - harmonic order; p - effective order of nonlinearity. (Note the term in brackets, the phase-matching function, has been separated from the rest of the expression in order to be consistent with the relevant literature).

  9. High pressure gas vessels for neutron scattering experiments

    CERN Document Server

    Done, R; Evans, B E; Bowden, Z A

    2010-01-01

    The combination of high pressure techniques with neutron scattering proves to be a powerful tool for studying the phase transitions and physical properties of solids in terms of inter-atomic distances. In our report we are going to review a high pressure technique based on a gas medium compression. This technique covers the pressure range up to ~0.7GPa (in special cases 1.4GPa) and typically uses compressed helium gas as the pressure medium. We are going to look briefly at scientific areas where high pressure gas vessels are intensively used in neutron scattering experiments. After that we are going to describe the current situation in high pressure gas technology; specifically looking at materials of construction, designs of seals and pressure vessels and the equipment used for generating high pressure gas.

  10. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Blood Pressure » Diagnosis of High Blood Pressure Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical ...

  11. DC-driven plasma gun: self-oscillatory operation mode of atmospheric-pressure helium plasma jet comprised of repetitive streamer breakdowns

    Science.gov (United States)

    Wang, Xingxing; Shashurin, Alexey

    2017-02-01

    This paper presents and studies helium atmospheric pressure plasma jet comprised of a series of repetitive streamer breakdowns, which is driven by pure DC high voltage (self-oscillatory behavior). The repetition frequency of the breakdowns is governed by the geometry of discharge electrodes/surroundings and gas flow rate. Each next streamer is initiated when the electric field on the anode tip recovers after the previous breakdown and reaches the breakdown threshold value of about 2.5 kV cm-1. One type of the helium plasma gun designed using this operational principle is demonstrated. The gun operates on about 3 kV DC high voltage and is comprised of the series of the repetitive streamer breakdowns at a frequency of about 13 kHz.

  12. Living with High Blood Pressure

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Living With High Blood Pressure If you have high blood pressure, the best thing to do is to talk ... help you track your blood pressure. Pregnancy Planning High blood pressure can cause problems for mother and baby. High ...

  13. Influence of excitation frequency on helium metastable density in atmospheric pressure DBD

    Science.gov (United States)

    Boisvert, J.-S.; Sadeghi, N.; Margot, J.; Massines, F.

    2016-09-01

    Diffuse dielectric barrier discharges in atmospheric-pressure helium was sustained over a wide range of excitation frequencies (50 kHz to 15 MHz). Emission spectroscopy and resonant absorption and laser absorption on He(23S) metastable atoms have been used to characterize different plasma regimes, which with increasing frequency changes from a low pressure glow discharge (APGD) to Townsend-like mode (TL) and finally to a continuously sustained plasma. This later can be in Ω mode (with uniform E-field) or RF- α mode (with sheath formation). Depending on applied power, the time-averaged He(23S) density remains below 3 1016 m-3 in TL and Ω modes, can reach 7 1016 m-3 in APGD and RF- α modes and up to 4 1017 m-3 in a combination of APGD and RF- α modes (Hybrid). Time-resolved He(23S) densities show an overshoot on the ignition phase, which in RF- α mode can be attributed to a secondary source of ionization involving metastable atoms.

  14. Floating Pressure Conversion and Equipment Upgrades of Two 3.5kw, 20k, Helium Refrigerators

    Science.gov (United States)

    Homan, Jonathan; Linza, Robert; Garcia, Sam; Vargas, Gerardo; Lauterbach, John; Ganni, Venkatarao (Rao); Sidi-Yekhlef, Ahmed; Creel, Jonathan; Norton, Robert; Urbin, John; Howe, Don

    2008-01-01

    Two helium refrigerators, each rated for 3.5KW at 20K, are used at NASA s Johnson Space Center (JSC) in Building No. 32 to provide cryo-pumping within two large thermal-vacuum chambers. These refrigerators were originally commissioned in 1996. Equipment refurbishment and upgrades to the controls of these refrigerators were recently completed. This paper describes some of the mechanical and control issues that necessitated the equipment refurbishment and controls change-over. It will describe the modifications and the new process control which allows the refrigerators to take advantage of the Ganni Cycle "floating pressure" control technology. The upgrades -- the controls philosophy change-over to the floating pressure control technology and the newly refurbished equipment -- have greatly improved the performance, stability, and efficiency of these two refrigerators. The upgrades have also given the operators more information and details about the operational status of the main components (compressors, expanders etc.) of the refrigerators at all operating conditions (i.e.: at various loads in the vacuum chambers). Capabilities, configuration, and performance data pre, and post, upgrading will be presented.

  15. Feasibility of high-helium natural gas exploration in the Presinian strata, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Jian Zhang

    2015-01-01

    Full Text Available Helium in China highly depends on import at present, so the most practical way to change the situation is searching for medium-to-large natural gas fields with high helium content. Therefore, the hydrocarbon accumulation mechanism and the helium origin of the Weiyuan high-helium natural gas reservoir have been analyzed to find out the feasibility of finding natural gas field with high helium content in the Presinian strata of the Sichuan Basin. Based on twelve outcrop sections and drilling data of four wells encountering the Presinian strata, the petrological features, sedimentary facies and source rocks of Presinian strata were systematically analyzed, which shows that the sedimentary formation developed in the Presinian is the Nanhua system, and the stratigraphic sequence revealed by outcrop section in the eastern margin includes the Nantuo, Datangpo, Gucheng and Liantuo Fms, and it is inferred that the same stratigraphic sequence may occur inside the basin. The Nantuo, Gucheng and Liantuo Fms are mainly glacial deposits of glutenite interbedded with mudstone; the Datangpo Fm is interglacial deposits of sandstone and shale, the lower part shale, rich in organic matter, is fairly good source rock. Further study showed that the Nantuo coarse-grained clastic reservoir, Datangpo source rock and the intruded granite “helium source rock” make up a good high-helium gas system. Controlled by the early rift, the thick Presinian sedimentary rocks occur primarily inside the rift. The distribution of sedimentary rocks and granite in the basin was predicted by use of the seismic data, which shows that the feasibility of finding high-helium gas reservoirs in Ziyang area of the Sichuan Basin is great.

  16. Homogeneous nucleation rate measurements of 1-propanol in helium: the effect of carrier gas pressure.

    Science.gov (United States)

    Brus, David; Zdímal, Vladimír; Stratmann, Frank

    2006-04-28

    Kinetics of homogeneous nucleation in supersaturated vapor of 1-propanol was studied using an upward thermal diffusion cloud chamber. Helium was used as a noncondensable carrier gas and the influence of its pressure on observed nucleation rates was investigated. The isothermal nucleation rates were determined by a photographic method that is independent on any nucleation theory. In this method, the trajectories of growing droplets are recorded using a charge coupled device camera and the distribution of local nucleation rates is determined by image analysis. The nucleation rate measurements of 1-propanol were carried out at four isotherms 260, 270, 280, and 290 K. In addition, the pressure dependence was investigated on the isotherms 290 K (50, 120, and 180 kPa) and 280 K (50 and 120 kPa). The isotherm 270 K was measured at 25 kPa and the isotherm 260 K at 20 kPa. The experiments confirm the earlier observations from several thermal diffusion chamber investigations that the homogeneous nucleation rate of 1-propanol tends to increase with decreasing total pressure in the chamber. In order to reduce the possibility that the observed phenomenon is an experimental artifact, connected with the generally used one-dimensional description of transfer processes in the chamber, a recently developed two-dimensional model of coupled heat, mass, and momentum transfer inside the chamber was used and results of both models were compared. It can be concluded that the implementation of the two-dimensional model does not explain the observed effect. Furthermore the obtained results were compared both to the predictions of the classical theory and to the results of other investigators using different experimental devices. Plotting the experimental data on the so-called Hale plot shows that our data seem to be consistent both internally and also with the data of others. Using the nucleation theorem the critical cluster sizes were obtained from the slopes of the individual isotherms

  17. Diagnosis of High Blood Pressure

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    Full Text Available ... High Blood Pressure Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living ... Confirming High Blood Pressure A blood pressure test is easy and painless and can be done in ...

  18. Diagnosis of High Blood Pressure

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    Full Text Available ... providers diagnose high blood pressure when blood pressure readings are consistently 140/90 mmHg or above. Confirming ... minutes before the test. To track blood pressure readings over a period of time, the health care ...

  19. Collisional-radiative model of helium microwave discharges at atmospheric pressure

    Science.gov (United States)

    Santos, M.; Alves, L. L.; Gadonna, K.; Belmonte, T.

    2011-10-01

    This paper presents a stationary collisional-radiative model to describe the behavior of helium microwave discharges (2.45 GHz), produced in cylindrical geometry (1 mm radius) at atmospheric pressure. The model couples the rate balance equations for the charged particles (electrons, He+ and He2+ions), the He(n excimers, to the two-term homogeneous and stationary electron Boltzmann equation,. The latter is solved using a coherent set of electron cross sections, adjusted to ensure good predictions of the swarm parameters and the Townsend ionization coefficient. The model was solved for typical 5x1014 cm-3 electron density and 2500 K gas temperature, yielding [He2+]/[He+] ~ 0.92 and [He2*]/[He] ~ 3.4x10-8. Results show also that the He2+ions are produced mainly from the 3-body conversion of He+ ions and lost by the corresponding reverse reaction together with diffusion and dissociative recombination. The He2*is produced by a 3-body reaction involving the 23P states and by the electron-stabilized recombination of He2+and is lost by electron dissociation. This paper presents a stationary collisional-radiative model to describe the behavior of helium microwave discharges (2.45 GHz), produced in cylindrical geometry (1 mm radius) at atmospheric pressure. The model couples the rate balance equations for the charged particles (electrons, He+ and He2+ions), the He(n excimers, to the two-term homogeneous and stationary electron Boltzmann equation,. The latter is solved using a coherent set of electron cross sections, adjusted to ensure good predictions of the swarm parameters and the Townsend ionization coefficient. The model was solved for typical 5x1014 cm-3 electron density and 2500 K gas temperature, yielding [He2+]/[He+] ~ 0.92 and [He2*]/[He] ~ 3.4x10-8. Results show also that the He2+ions are produced mainly from the 3-body conversion of He+ ions and lost by the corresponding reverse reaction together with diffusion and dissociative recombination. The He2*is produced

  20. Pressure Dome for High-Pressure Electrolyzer

    Science.gov (United States)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  1. Discharge physics and influence of the modulation on helium DBD modes in the medium-frequency range at atmospheric pressure

    Science.gov (United States)

    Boisvert, Jean-Sébastien; Margot, Joëlle; Massines, Françoise

    2017-04-01

    In this paper the recently reported hybrid mode (a dielectric barrier discharge (DBD) excited by an electric field oscillating at about 1 MHz) is investigated using space and time-resolved imaging together with electrical measurements. In contrast with the helium low-frequency DBD, at 1.6 MHz the light emission is desynchronized with the discharge current. It rather depends on the enhanced rate of stepwise excitation resulting from the massive secondary emission occurring 0.15Ƭ after the discharge current maximum (Ƭ is the excitation wave period). The consequence of ion impacts on the dielectric surfaces is a higher gas and dielectric temperatures as compared to typical helium DBDs. The electrical behavior and the gas temperature of a pulsed dielectric-barrier discharge operated at 1.6 MHz are also described in this paper as a function of the repetition rate (varying from 1 Hz to 10 kHz). The gas temperature is reduced when repetition rates higher or equal to 10 Hz is used. This is related to the gas renewal rate of 8.3 Hz, i.e., gas residence time of 120 ms in our conditions. In addition, due to the memory effect in the gas, the gas gap voltage decreases as the repetition rate increases. However, beyond 100 Hz, the power decreases and the gas gap voltage increases again. As a consequence, for a given power density, the optimal repetition rate is 100 Hz which minimizes the gas temperature without reducing the power density. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

  2. High pressure ratio cryocooler with integral expander and heat exchanger

    Science.gov (United States)

    Crunkleton, J. A.; Smith, J. L., Jr.; Iwasa, Y.

    A new 1 W, 4.2 K cryocooler is under development that is intended to miniaturize helium temperature refrigeration systems using a high-pressure-ratio Collins-type cycle. The configuration resulted from optimization studies of a saturated vapor compression (SCV) cycle that employs miniature parallel-plate heat exchangers. The basic configuration is a long displacer in a close-fitting, thin-walled cylinder. The displacer-to-cylinder gap is the high-pressure passage of the heat exchanger, and the low-pressure passage is formed by a thin tube over the OD of the cylinder. A solenoid-operated inlet valve admits 40 atm helium to the displacer-to-cylinder gap at room temperature, while the solenoid-operated exhaust valve operates at 4 atm. The single-stage cryocooler produces 1 W of refrigeration at 40 K without precooling and at 20 K with liquid nitrogen precooling.

  3. Chromium at High Pressure

    Science.gov (United States)

    Jaramillo, Rafael

    2012-02-01

    Chromium has long served as the archetype of spin density wave magnetism. Recently, Jaramillo and collaborators have shown that Cr also serves as an archetype of magnetic quantum criticality. Using a combination of x-ray diffraction and electrical transport measurements at high pressures and cryogenic temperatures in a diamond anvil cell, they have demonstrated that the N'eel transition (TN) can be continuously suppressed to zero, with no sign of a concurrent structural transition. The order parameter undergoes a broad regime of exponential suppression, consistent with the weak coupling paradigm, before deviating from a BCS-like ground state within a narrow but accessible quantum critical regime. The quantum criticality is characterized by mean field scaling of TN and non mean field scaling of the transport coefficients, which points to a fluctuation-induced reconstruction of the critical Fermi surface. A comparison between pressure and chemical doping as means to suppress TN sheds light on different routes to the quantum critical point and the relevance of Fermi surface nesting and disorder at this quantum phase transition. The work by Jaramillo et al. is broadly relevant to the study of magnetic quantum criticality in a physically pure and theoretically tractable system that balances elements of weak and strong coupling. [4pt] [1] R. Jaramillo, Y. Feng, J. Wang & T. F. Rosenbaum. Signatures of quantum criticality in pure Cr at high pressure. Proc. Natl. Acad. Sci. USA 107, 13631 (2010). [0pt] [2] R. Jaramillo, Y. Feng, J. C. Lang, Z. Islam, G. Srajer, P. B. Littlewood, D. B. McWhan & T. F. Rosenbaum. Breakdown of the Bardeen-Cooper-Schrieffer ground state at a quantum phase transition. Nature 459, 405 (2009).

  4. Numerical simulation of a direct current glow discharge in atmospheric pressure helium

    Science.gov (United States)

    Yin, Zeng-Qian; Wang, Yan; Zhang, Pan-Pan; Zhang, Qi; Li, Xue-Chen

    2016-12-01

    Characteristics of a direct current (DC) discharge in atmospheric pressure helium are numerically investigated based on a one-dimensional fluid model. The results indicate that the discharge does not reach its steady state till it takes a period of time. Moreover, the required time increases and the current density of the steady state decreases with increasing the gap width. Through analyzing the spatial distributions of the electron density, the ion density and the electric field at different discharge moments, it is found that the DC discharge starts with a Townsend regime, then transits to a glow regime. In addition, the discharge operates in a normal glow mode or an abnormal glow one under different parameters, such as the gap width, the ballast resistors, and the secondary electron emission coefficients, judged by its voltage-current characteristics. Project supported by the National Natural Science Foundation of China (Grant Nos. 11575050 and 10805013), the Midwest Universities Comprehensive Strength Promotion Project, the Natural Science Foundation of Hebei Province, China (Grant Nos. A2016201042 and A2015201092), and the Research Foundation of Education Bureau of Hebei Province, China (Grant No. LJRC011).

  5. Modelling of HTR Confinement Behaviour during Accidents Involving Breach of the Helium Pressure Boundary

    Directory of Open Access Journals (Sweden)

    Joan Fontanet

    2009-01-01

    Full Text Available Development of HTRs requires the performance of a thorough safety study, which includes accident analyses. Confinement building performance is a key element of the system since the behaviour of aerosol and attached fission products within the building is of an utmost relevance in terms of the potential source term to the environment. This paper explores the available simulation capabilities (ASTEC and CONTAIN codes and illustrates the performance of a postulated HTR vented confinement under prototypical accident conditions by a scoping study based on two accident sequences characterized by Helium Pressure Boundary breaches, a small and a large break. The results obtained indicate that both codes predict very similar thermal-hydraulic responses of the confinement both in magnitude and timing. As for the aerosol behaviour, both codes predict that most of the inventory coming into the confinement is eventually depleted on the walls and only about 1% of the aerosol dust is released to the environment. The crosscomparison of codes states that largest differences are in the intercompartmental flows and the in-compartment gas composition.

  6. Array of surface-confined glow discharges in atmospheric pressure helium: Modes and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Li, D.; Liu, D. X., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi (China); Nie, Q. Y.; Li, H. P. [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Chen, H. L. [Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Kong, M. G., E-mail: liudingxin@gmail.com, E-mail: mglin5g@gmail.com [Center for Plasma Biomedicine, State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Shaanxi (China); Frank Reidy Center for Bioelectrics, Old Dominion University, Norfolk, Virginia 23508 (United States); Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2014-05-19

    Array of atmospheric pressure surface discharges confined by a two-dimensional hexagon electrode mesh is studied for its discharge modes and temporal evolution so as to a theoretical underpinning to their growing applications in medicine, aerodynamic control, and environmental remediation. Helium plasma surface-confined by one hexagon-shaped rim electrode is shown to evolve from a Townsend mode to a normal and abnormal glow mode, and its evolution develops from the rim electrodes as six individual microdischarges merging in the middle of the hexagon mesh element. Within one hexagon element, microdischarges remain largely static with the mesh electrode being the instantaneous cathode, but move towards the hexagon center when the electrode is the instantaneous anode. On the entire array electrode surface, plasma ignition is found to beat an unspecific hexagon element and then spreads to ignite surrounding hexagon elements. The spreading of microdischarges is in the form of an expanding circle at a speed of about 3 × 10{sup 4} m/s, and their quenching starts in the location of the initial plasma ignition. Plasma modes influence how input electrical power is used to generate and accelerate electrons and as such the reaction chemistry, whereas plasma dynamics are central to understand and control plasma instabilities. The present study provides an important aspect of plasma physics of the atmospheric surface-confined discharge array and a theoretical underpinning to its future technological innovation.

  7. Heat transfer through Rutherford superconducting cable with novel pattern of polyimide electrical insulation in pressurized superfluid helium environment

    Science.gov (United States)

    Chorowski, Maciej; Polinski, Jaroslaw; Strychalski, Michal

    2012-06-01

    Future LHC accelerator luminosity upgrade will increase a beam losses heat deposition in the superconducting magnet coils. Main barrier of the heat evacuation from the coils made of Rutherford type cables is a cable electrical insulation. The insulation is made of polyimide tapes wrapped around the cable in a special configuration. Presently used insulation wrapping schemes constitute very good electrical insulation with relatively low heat transport ability. Therefore a new insulation wrapping schemes with enhanced helium permeability and adequate dielectric properties have been developed at CERN. An experimental comparative study of heat transfer perpendicular to the Rutherford type cable, for an old and new insulation wrapping schemes have been accomplished at Wroclaw University of Technology. The tests have been performed in pressurized superfluid helium conditions, and at 60 MPa of the sample applied external pressure simulating the Lorentz forces. This paper presents the measurements methodology and gives experimental results.

  8. High Blood Pressure

    Science.gov (United States)

    ... mmHg People read "118 over 76" millimeters of mercury. Normal Blood Pressure Normal blood pressure for adults ... health. Share your story with other women on Facebook . The Heart Truth campaign offers a variety of ...

  9. High Pressure Cryocooling of Protein Crystals: The Enigma of Water

    Science.gov (United States)

    Gruner, Sol M.

    2010-03-01

    A novel high-pressure cryocooling technique for preparation biological samples for x-ray analysis is described. The method, high-pressure cryocooling, involves cooling samples to cryogenic temperatures (e.g., 100 K) in high-pressure Helium gas (up to 200 MPa). It bears both similarities and differences to high-pressure cooling methods that have been used to prepare samples for electron microscopy, and has been especially useful for cryocooling of macromolecular crystals for x-ray diffraction. Examples will be given where the method has been effective in providing high quality crystallographic data for difficult samples, such as cases where ligands needed to be stabilized in binding sites to be visualized, or where very high resolution data were required. The talk concludes with a discussion of data obtained by high-pressure cryocooling that pertains to two of the most important problems in modern science: the enigma of water and how water affects the activity of proteins.

  10. High Blood Pressure Increasing Worldwide

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162977.html High Blood Pressure Increasing Worldwide And health risks may appear even ... of people around the world with elevated or high blood pressure increases, so do the number of deaths linked ...

  11. Medications for High Blood Pressure

    Science.gov (United States)

    ... Consumers Home For Consumers Consumer Updates Medications for High Blood Pressure Share Tweet Linkedin Pin it More sharing options ... age and you cannot tell if you have high blood pressure by the way you feel, so have your ...

  12. What Causes High Blood Pressure?

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Causes of High Blood Pressure Changes, either from genes or the environment, in ... and blood vessel structure and function. Biology and High Blood Pressure Researchers continue to study how various changes in ...

  13. Effects of metastable species in helium and argon atmospheric pressure plasma jets (APPJs) on inactivation of periodontopathogenic bacteria

    Science.gov (United States)

    Yoon, Sung-Young; Kim, Kyoung-Hwa; Seol, Yang-Jo; Kim, Su-Jeong; Bae, Byeongjun; Huh, Sung-Ryul; Kim, Gon-Ho

    2016-05-01

    The helium and argon have been widely used as discharge gases in atmospheric pressure plasma jets (APPJs) for bacteria inactivation. The APPJs show apparent different in bullet propagation speed and bacteria inactivation rate apparently vary with discharge gas species. This work shows that these two distinctive features of APPJs can be linked through one factor, the metastable energy level. The effects of helium and argon metastable species on APPJ discharge mechanism for reactive oxygen nitrogen species (RONS) generation in APPJs are investigated by experiments and numerical estimation. The discharge mechanism is investigated by using the bullet velocity from the electric field which is obtained with laser induced fluorescence (LIF) measurement. The measured electric field also applied on the estimation of RONS generation, as electron energy source term in numerical particle reaction. The estimated RONS number is verified by comparing NO and OH densities to the inactivation rate of periodontitis bacteria. The characteristic time for bacteria inactivation of the helium-APPJ was found to be 1.63 min., which is significantly less than that of the argon-APPJ, 12.1 min. In argon-APPJ, the argon metastable preserve the energy due to the lack of the Penning ionization. Thus the surface temperature increase is significantly higher than helium-APPJ case. It implies that the metastable energy plays important role in both of APPJ bullet propagation and bacteria inactivation mechanism.

  14. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... page from the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... are consistently 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  15. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... page from the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... are consistently 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  16. Controlling your high blood pressure

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000101.htm Controlling your high blood pressure To use the sharing features on this page, ... JavaScript. Hypertension is another term used to describe high blood pressure. High blood pressure can lead to: Stroke Heart ...

  17. Diagnosis of High Blood Pressure

    Science.gov (United States)

    ... page from the NHLBI on Twitter. Diagnosis of High Blood Pressure For most patients, health care providers diagnose high ... are consistently 140/90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless ...

  18. [High Pressure Gas Tanks

    Science.gov (United States)

    Quintana, Rolando

    2002-01-01

    Four high-pressure gas tanks, the basis of this study, were especially made by a private contractor and tested before being delivered to NASA Kennedy Space Center. In order to insure 100% reliability of each individual tank the staff at KSC decided to again submit the four tanks under more rigorous tests. These tests were conducted during a period from April 10 through May 8 at KSC. This application further validates the predictive safety model for accident prevention and system failure in the testing of four high-pressure gas tanks at Kennedy Space Center, called Continuous Hazard Tracking and Failure Prediction Methodology (CHTFPM). It is apparent from the variety of barriers available for a hazard control that some barriers will be more successful than others in providing protection. In order to complete the Barrier Analysis of the system, a Task Analysis and a Biomechanical Study were performed to establish the relationship between the degree of biomechanical non-conformities and the anomalies found within the system on particular joints of the body. This relationship was possible to obtain by conducting a Regression Analysis to the previously generated data. From the information derived the body segment with the lowest percentage of non-conformities was the neck flexion with 46.7%. Intense analysis of the system was conducted including Preliminary Hazard Analysis (PHA), Failure Mode and Effect Analysis (FMEA), and Barrier Analysis. These analyses resulted in the identification of occurrences of conditions, which may be becoming hazardous in the given system. These conditions, known as dendritics, may become hazards and could result in an accident, system malfunction, or unacceptable risk conditions. A total of 56 possible dendritics were identified. Work sampling was performed to observe the occurrence each dendritic. The out of control points generated from a Weighted c control chart along with a Pareto analysis indicate that the dendritics "Personnel not

  19. Very High Temperature Test of Alloy617 Compact Heat Exchanger in Helium Experimental Loop

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Soo; Park, Byung-Ha; Kim, Eung-Seon [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The Intermediate Heat eXchanger (IHX) is a key-challenged high temperature component which determines the efficiency and the economy of VHTR system. Heat generated in the VHTR fuel block is transferred from the VHTR to the intermediate loop through IHX. In the present, the shell-helical tube heat exchanger is generally used as IHX of the helium cooled reactor. Recently, a Printed Circuit Heat Exchanger (PCHE) is one of the candidates for the IHX in a VHTR because its operation temperature and pressure are larger than any other compact heat exchanger types. These test results show that there is no problem in operation of HELP at the very high temperature experimental condition and the alloy617 compact heat exchanger can be operated in the very high temperature condition above 850℃. In the future, the high temperature structural analysis will be studied to estimate the thermal stress during transient and thermal shock condition. The conditions and evaluation standard for the alloy 617 diffusion bonding will be minutely studied to fabricate the large-scale PCHE for the high temperature condition.

  20. High-pressure neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory

    2011-01-10

    This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.

  1. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... and Obesity Smoking and Your Heart Stroke Send a link to NHLBI to someone by E-MAIL | ... 90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless and ...

  2. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... of Intramural Research Research Resources Research Meeting Summaries Technology Transfer Clinical Trials What Are Clinical Trials? Children & ... blood pressure is due to other conditions or medicines or if you have primary high blood pressure. ...

  3. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... to keep a written log of all your results. Whenever you have an appointment with the health ... appointments to diagnose high blood pressure. Using the results of your blood pressure test, your health care ...

  4. High Blood Pressure in Pregnancy

    Science.gov (United States)

    ... of the baby. Controlling your blood pressure during pregnancy and getting regular prenatal care are important for ... your baby. Treatments for high blood pressure in pregnancy may include close monitoring of the baby, lifestyle ...

  5. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... ask for your readings. Blood Pressure Severity and Type Your health care provider usually takes 2–3 ... any other location. Health care providers diagnose this type of high blood pressure by reviewing readings in ...

  6. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... ask for your readings. Blood Pressure Severity and Type Your health care provider usually takes 2–3 ... any other location. Health care providers diagnose this type of high blood pressure by reviewing readings in ...

  7. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... above. Confirming High Blood Pressure A blood pressure test is easy and painless and can be done ... provider’s office or clinic. To prepare for the test: Don’t drink coffee or smoke cigarettes for ...

  8. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... readings. Blood Pressure Severity and Type Your health care provider usually takes 2–3 readings at several medical appointments to diagnose high blood pressure. Using the ...

  9. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... and Obesity Smoking and Your Heart Stroke Send a link to NHLBI to someone by E-MAIL | ... 90 mmHg or above. Confirming High Blood Pressure A blood pressure test is easy and painless and ...

  10. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... above. Confirming High Blood Pressure A blood pressure test is easy and painless and can be done ... provider’s office or clinic. To prepare for the test: Don’t drink coffee or smoke cigarettes for ...

  11. The effects of added hydrogen on a helium atmospheric-pressure plasma jet ambient desorption/ionization source.

    Science.gov (United States)

    Wright, Jonathan P; Heywood, Matthew S; Thurston, Glen K; Farnsworth, Paul B

    2013-03-01

    We present mass spectrometric data demonstrating the effect that hydrogen has on a helium-based dielectric-barrier discharge (DBD) atmospheric-pressure plasma jet used as an ambient desorption/ionization (ADI) source. The addition of 0.9 % hydrogen to the helium support gas in a 35-W plasma jet increased signals for a range of test analytes, with enhancement factors of up to 68, without proportional increases in background levels. The changes in signal levels result from a combination of changes in the desorption kinetics from the surface and increased ion production in the gas phase. The enhancement in ADI-MS performance despite the quenching of key plasma species reported in earlier studies suggests that ionization with a H2/He plasma jet is the result of an alternate mechanism involving the direct generation of ionized hydrogen.

  12. Flux of OH and O radicals onto a surface by an atmospheric-pressure helium plasma jet measured by laser-induced fluorescence

    Science.gov (United States)

    Yonemori, Seiya; Ono, Ryo

    2014-03-01

    The atmospheric-pressure helium plasma jet is of emerging interest as a cutting-edge biomedical device for cancer treatment, wound healing and sterilization. Reactive oxygen species such as OH and O radicals are considered to be major factors in the application of biological plasma. In this study, density distribution, temporal behaviour and flux of OH and O radicals on a surface are measured using laser-induced fluorescence. A helium plasma jet is generated by applying pulsed high voltage of 8 kV with 10 kHz using a quartz tube with an inner diameter of 4 mm. To evaluate the relation between the surface condition and active species production, three surfaces are used: dry, wet and rat skin. When the helium flow rate is 1.5 l min-1, radial distribution of OH density on the rat skin surface shows a maximum density of 1.2 × 1013 cm-3 at the centre of the plasma-mediated area, while O atom density shows a maximum of 1.0 × 1015 cm-3 at 2.0 mm radius from the centre of the plasma-mediated area. Their densities in the effluent of the plasma jet are almost constant during the intervals of the discharge pulses because their lifetimes are longer than the pulse interval. Their density distribution depends on the helium flow rate and the surface humidity. With these results, OH and O production mechanisms in the plasma jet and their flux onto the surface are discussed.

  13. High Blood Pressure

    Science.gov (United States)

    ... giving Gift and estate planning Circle of Champions Corporate sponsorship Join us at an event The Hope ... blood pressure is the #2 cause of kidney failure. It accounts for about one-fourth of all ...

  14. High Blood Pressure (Hypertension)

    Science.gov (United States)

    ... possible. Practice healthy coping techniques, such as muscle relaxation, deep breathing or meditation. Getting regular physical activity ... you monitor your blood pressure at home. Practice relaxation or slow, deep breathing. Practice taking deep, slow ...

  15. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  16. High Blood Pressure and Women

    Science.gov (United States)

    ... blood pressure during a previous pregnancy, have a family history of high blood pressure or mild kidney disease. The combination of birth ... Print (PDF) | Online How to Measure Your Blood Pressure (PDF) Questions To Ask ... FREE digital-only, quarterly magazine for patients, families, and caregivers, which focuses on the prevention and ...

  17. Low temperature mechanical properties of steels containing high concentrations of helium

    Energy Technology Data Exchange (ETDEWEB)

    Ullmaier, H. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Camus, E. [Hahn-Meitner-Institut Berlin GmbH, Glienicker Strasse 100, D-14109 Berlin (Germany)

    1997-11-01

    Results of tensile tests and hardness measurements in the temperature range 25-400 C are reported for ferritic-martensitic steels and s.a. 316 L austenitic steel. Helium concentrations up to 1 at.% have beenintroduced into these materials by {alpha}-particle (0-25 MeV) implantation and He/Fe dual-beam (15/300 keV) irradiation, respectively. In the latter case displacement damage up to 50 dpa was produced simultaneously with the introduction of He. From a preliminary analysis of the results and a comparison with earlier data it may be concluded that for temperatures up to at least 400 C the observed hardening is dominated by displacement damage. Only for very high helium concentrations around 1 at.% a moderate further increase of hardness is found, indicating that helium does not have a drastic effect on the mechanical properties of the investigated alloys. (orig.). 31 refs.

  18. What Is High Blood Pressure?

    Science.gov (United States)

    ... Disease Venous Thromboembolism Aortic Aneurysm More What is High Blood Pressure? Updated:Oct 31,2016 First, let’s define high ... resources . This content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP Introduction What ...

  19. Comparison of melting and crystallization behaviors of polylactide under high-pressure CO2, N2, and He

    Science.gov (United States)

    Nofar, M.; Tabatabaei, A.; Ameli, A.; Park, C. B.

    2014-05-01

    This study investigated the melting and crystallization behaviors of polylactide (PLA) under high-pressure CO2, N2, and helium (He) using a high-pressure differential scanning calorimeter. The results showed that the PLA's melting temperature was depressed only in contact with pressurized CO2 where at high CO2 pressures the lubricating gas molecules induced more imperfect melt and cold crystals during the cooling and heating cycles, respectively. PLA's melt crystallization was analyzed during nonisothermal processes. Despite the effect of dissolved CO2 that expedited the PLA's crystallization rate, N2 showed almost a neutral impact on the PLA's crystallization kinetics. Because of the lower solubility, N2 gas content dissolved in the PLA had a diminutive plasticization effect, and thereby it could only counterbalance its negative hydraulic pressure effect. Moreover, as the helium pressure increased, the PLA's final crystallinity was reduced due to the dominant effect of helium's hydraulic pressure.

  20. D0 Silicon Upgrade: Gas Helium Storage Tank Pressure Vessel Engineering Note

    Energy Technology Data Exchange (ETDEWEB)

    Rucinski, Russ; /Fermilab

    1996-11-11

    This is to certify that Beaird Industries, Inc. has done a white metal blast per SSPC-SP5 as required per specifications on the vessel internal. Following the blast, a black light inspection was performed by Beaird Quality Control personnel to assure that all debris, grease, etc. was removed and interior was clean prior to closing vessel for helium test.

  1. Scheelite CaWO{sub 4} at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Grzechnik, Andrzej [Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany); Crichton, Wilson A [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble cedex (France); Hanfland, Michael [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble cedex (France); Smaalen, Sander van [Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany)

    2003-11-05

    The high-pressure room-temperature behaviour of scheelite CaWO{sub 4} (I4{sub 1}/a,Z = 4) is studied using high-resolution synchrotron angle-dispersive x-ray powder diffraction in diamond anvil cells loaded with helium or a mixture of methanol and ethanol as the pressure-transmitting media. At about 10 GPa, there occurs a phase transition to the fergusonite type (I 2/a,Z = 4) without any discontinuity in the pressure dependence of the unit cell volumes. These observations are discussed in relation to the high-pressure-high-temperature systematics of the AMX{sub 4} and AX{sub 2} type compounds.

  2. Common High Blood Pressure Myths

    Science.gov (United States)

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Common High Blood Pressure Myths Updated:Dec 9,2016 Knowing the facts ... health. This content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP Introduction What ...

  3. High Pressure Equation of State Studies Using Ethanol-Methanol And Argon As Pressure Medium

    Science.gov (United States)

    Godwal, B. K.; Speziale, S.; Clark, S.; Yan, J.; Jeanloz, R.

    2008-12-01

    Experimental high pressure studies are extremely important to planetary science, material science and to the development of condensed matter theory. With experimental difficulties in creating the extreme pressure temperature conditions appropriate to planetary interiors, the approach used is to obtain the thermodynamic data on materials of interest by extrapolating the condensed matter theory which has been benchmarked with the outcome of high pressure experiments to the available high pressures. However the high pressure data used to match the theory heavily depends on the use of pressure media; like ethanol-methanol, silicon oil, argon and helium. Unfortunately still there exist controversy in the literature even with the use of helium as pressure medium as illustrated by the unsettled debate on Zn and Os among different groups. We have measured the equation of state of intermetallic compound AuIn2 and Cd0.8Hg0.2 alloy using ethanol-methanol and argon to the pressure of 20 GPa to confirm the appearance of anomalies in the data due to occurrence of subtle electronic phase transitions. However these anomalies can also be attributed to oriented lattice strains and local non-hydrostatic conditions. We have tried to remove these at room temperature by stabilizing the sample in argon medium in the diamond anvil cell with proper annealing as indicated by the uniformity of the pressure across the sample by ruby fluorescence measurements. We will present the data revealing the electronic transition in AuIn2 at 2.7 GPa and in Cd0.8Hg0.2 near 9 and 18 GPa.

  4. Stroke and High Blood Pressure

    Science.gov (United States)

    ... More How High Blood Pressure Can Lead to Stroke Updated:Dec 2,2016 Stroke and high blood ... Changes That Matter • Find Tools & Resources Show Your Stroke Support! Show your stroke support with our new ...

  5. Nanomaterials under high-pressure.

    Science.gov (United States)

    San-Miguel, Alfonso

    2006-10-01

    The use of high-pressure for the study and elaboration of homogeneous nanostructures is critically reviewed. Size effects, the interaction between nanostructures and guest species or the interaction of the nanosystem with the pressure transmitting medium are emphasized. Phase diagrams and the possibilities opened by the combination of pressure and temperature for the elaboration of new nanomaterials is underlined through the examination of three different systems: nanocrystals, nano-cage materials which include fullerites and group-14 clathrates, and single wall nanotubes. This tutorial review is addressed to scientist seeking an introduction or a panoramic view of the study of nanomaterials under high-pressure.

  6. Ultra high vacuum pumping system and high sensitivity helium leak detector

    Science.gov (United States)

    Myneni, Ganapati Rao

    1997-01-01

    An improved helium leak detection method and apparatus are disclosed which increase the leak detection sensitivity to 10.sup.-13 atm cc s.sup.-1. The leak detection sensitivity is improved over conventional leak detectors by completely eliminating the use of o-rings, equipping the system with oil-free pumping systems, and by introducing measured flows of nitrogen at the entrances of both the turbo pump and backing pump to keep the system free of helium background. The addition of dry nitrogen flows to the system reduces backstreaming of atmospheric helium through the pumping system as a result of the limited compression ratios of the pumps for helium.

  7. High-Pressure Vibrational Spectroscopy.

    Science.gov (United States)

    Pogson, Mark

    1987-09-01

    Available from UMI in association with The British Library. Requires signed TDF. The study of solids at high pressure and variable temperature enables development of accurate interatomic potential functions over wide ranges of interatomic distances. A review of the main models used in the determination of these potentials is given in Chapter one. A discussion of phonon frequency as a variable physical parameter reflecting the interatomic potential is given. A high pressure Raman study of inorganic salts of the types MSCN, (M = K,Rb,Cs & NH_4^+ ) and MNO_2, (M = K,Na) has been completed. The studies have revealed two new phases in KNO_2 and one new phase in NaNO _2 at high pressure. The accurate phonon shift data have enabled the determination of the pure and biphasic stability regions of the phases of KNO _2. A discussion of the B1, B2 relationship of univalent nitrites is also given. In the series of thiocyanates studied new phases have been found in all four materials. In both the potassium and rubidium salts two new phases have been detected, and in the ceasium salt one new phase has been detected, all at high pressure, from accurate phonon shift data. These transitions are discussed in terms of second-order mechanisms with space groups suggested for all phases, based on Landau's theory of second-order phase transitions. In the ammonium salt one new phase has been detected. This new phase transition has been interpreted as a second-order transition. The series of molecular crystals CH_3 HgX, (X = Cl,Br & I) has been studied at high pressure and at variable temperature. In Chapter five, their phase behaviour at high pressure is detailed along with the pressure dependencies of their phonon frequencies. In the chloride and the bromide two new phases have been detected. In the bromide one has been detected at high temperature and one at high pressure, and latter being interpreted as the stopping of the methyl rotation. In the chloride one phase has been found at

  8. Determination of the most efficient target tissue and helium pressure for biolistic transformation of oil palm (Elaeis guineensis Jacq.

    Directory of Open Access Journals (Sweden)

    Amornrat Phongdara

    2008-03-01

    Full Text Available An efficient genetic transformation system for oil palm using particle bombardment was established. The transformation was performed using the pCAMBIA 1302 DNA which contains the green fluorescent protein (mgfp5 reporter gene and the selectable marker hygromycin phosphotransferase (hph gene. Oil palm explants were bombarded under the following conditions: rupture disk to macrocarrier distance, 11 mm; macrocarrier to target tissue, 90 mm and using 1 μm gold particles as microcarrier. Four different pressures of helium were tested with three types of target tissues (mature embryo, embryogenic callus and young seedlings. From the transformation efficiency, calli were much more efficiently transformed in the biolistic process compared with mature embryos and seedlings. A 100% transformation efficiency for DNA delivery into callus oil palm explants was obtained at 850 psi helium pressures, for embryos a maximum 81.8% efficiency required 850 psi and for seedlings a maximum 75.9% efficiency required 1,550 psi. Using a confocal laser scanning microscope, and appropriate filters to block out the red fluorescence of chlorophyll, expression of the GFP gene was observed in all three bombarded explant types by a bright-green fluorescence. The mgfp5 gene was still present more than 8 months after bombardment, hence it indicated the stability of transgene in those transformants.

  9. Flow field analysis of high-speed helium turboexpander for cryogenic refrigeration and liquefaction cycles

    Science.gov (United States)

    Sam, Ashish Alex; Ghosh, Parthasarathi

    2017-03-01

    Turboexpander constitutes one of the vital components of Claude cycle based helium refrigerators and liquefiers that are gaining increasing technological importance. These turboexpanders which are of radial inflow in configuration are generally high-speed micro turbines, due to the low molecular weight and density of helium. Any improvement in efficiency of these machines requires a detailed understanding of the flow field. Computational Fluid Dynamics analysis (CFD) has emerged as a necessary tool for the determination of the flow fields in cryogenic turboexpanders, which is often not possible through experiments. In the present work three-dimensional transient flow analysis of a cryogenic turboexpander for helium refrigeration and liquefaction cycles were performed using Ansys CFX®, to understand the flow field of a high-speed helium turboexpander, which in turn will help in taking appropriate decisions regarding modifications of established design methodology for improved efficiency of these machines. The turboexpander is designed based on Balje's nsds diagram and the inverse design blade profile generation formalism prescribed by Hasselgruber and Balje. The analyses include the study of several losses, their origins, the increase in entropy due to these losses, quantification of losses and the effects of various geometrical parameters on these losses. Through the flow field analysis it was observed that in the nozzle, flow separation at the nozzle blade suction side and trailing edge vortices resulted in loss generation, which calls for better nozzle blade profile. The turbine wheel flow field analysis revealed that the significant geometrical parameters of the turbine wheel blade like blade inlet angle, blade profile, tip clearance height and trailing edge thickness need to be optimised for improved performance of the turboexpander. The detailed flow field analysis in this paper can be used to improve the mean line design methodology for turboexpanders used

  10. Numerical Modeling of the Atmospheric-Pressure Helium Plasma Formed During Spark-to-Glow Discharge Transition

    Science.gov (United States)

    Demkin, V. P.; Melnichuk, S. V.

    2017-06-01

    Results of numerical experiment on modeling of the atmospheric-pressure plasma formed during the spark-to-glow discharge transition in helium in low-current non-stationary plasmatron are presented. The numerical experiment is performed using the developed 2D physical and mathematical plasma model in the drift-diffusion approximation. Results of numerical calculation of the dynamics of discharge evolution are confirmed by the experimental data on the atmospheric-pressure plasma dynamics formed in the plasmatron during the spark-to-glow discharge transition. It is demonstrated that with preset initial conditions characteristic for spark breakdown, further discharge evolution leads to the formation of the near-cathode zone of the potential drop and the pulsed behavior of the electric current of the discharge. After the current pulse, the discharge transforms into the quasi-stationary mode with parameters characteristic for the glow discharge with monotonically increasing electric current and transverse dimensions of the plasma column.

  11. Raman Spectroscopy at High Pressures

    Directory of Open Access Journals (Sweden)

    Alexander F. Goncharov

    2012-01-01

    Full Text Available Raman spectroscopy is one of the most informative probes for studies of material properties under extreme conditions of high pressure. The Raman techniques have become more versatile over the last decades as a new generation of optical filters and multichannel detectors become available. Here, recent progress in the Raman techniques for high-pressure research and its applications in numerous scientific disciplines including physics and chemistry of materials under extremes, earth and planetary science, new materials synthesis, and high-pressure metrology will be discussed.

  12. Thermal hydraulic performance testing of printed circuit heat exchangers in a high-temperature helium test facility

    Energy Technology Data Exchange (ETDEWEB)

    Sai K. Mylavarapu; Xiaodong Sun; Richard E. Glosup; Richard N. Christensen; Michael W. Patterson

    2014-04-01

    In high-temperature gas-cooled reactors, such as a very high temperature reactor (VHTR), an intermediate heat exchanger (IHX) is required to efficiently transfer the core thermal output to a secondary fluid for electricity generation with an indirect power cycle and/or process heat applications. Currently, there is no proven high-temperature (750–800 °C or higher) compact heat exchanger technology for high-temperature reactor design concepts. In this study, printed circuit heat exchanger (PCHE), a potential IHX concept for high-temperature applications, has been investigated for their heat transfer and pressure drop characteristics under high operating temperatures and pressures. Two PCHEs, each having 10 hot and 10 cold plates with 12 channels (semicircular cross-section) in each plate are fabricated using Alloy 617 plates and tested for their performance in a high-temperature helium test facility (HTHF). The PCHE inlet temperature and pressure were varied from 85 to 390 °C/1.0–2.7 MPa for the cold side and 208–790 °C/1.0–2.7 MPa for the hot side, respectively, while the mass flow rate of helium was varied from 15 to 49 kg/h. This range of mass flow rates corresponds to PCHE channel Reynolds numbers of 950 to 4100 for the cold side and 900 to 3900 for the hot side (corresponding to the laminar and laminar-to-turbulent transition flow regimes). The obtained experimental data have been analyzed for the pressure drop and heat transfer characteristics of the heat transfer surface of the PCHEs and compared with the available models and correlations in the literature. In addition, a numerical treatment of hydrodynamically developing and hydrodynamically fully-developed laminar flow through a semicircular duct is presented. Relations developed for determining the hydrodynamic entrance length in a semicircular duct and the friction factor (or pressure drop) in the hydrodynamic entry length region for laminar flow through a semicircular duct are given. Various

  13. Steam Oxidation at High Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon R. [NETL; Carney, Casey [URS

    2013-07-19

    A first high pressure test was completed: 293 hr at 267 bar and 670{degrees}C; A parallel 1 bar test was done for comparison; Mass gains were higher for all alloys at 267 bar than at 1 bar; Longer term exposures, over a range of temperatures and pressures, are planned to provide information as to the commercial implications of pressure effects; The planned tests are at a higher combination of temperatures and pressures than in the existing literature. A comparison was made with longer-term literature data: The short term exposures are largely consistent with the longer-term corrosion literature; Ferritic steels--no consistent pressure effect; Austenitic steels--fine grain alloys less able to maintain protective chromia scale as pressure increases; Ni-base alloys--more mass gains above 105 bar than below. Not based on many data points.

  14. High Blood Pressure Prevention

    Science.gov (United States)

    ... or "no added salt." Look for the sodium content in milligrams and the Percent Daily Value. Aim for foods that are less than 5 percent of the Daily Value of sodium. Foods with 20 percent or more Daily Value of sodium are considered high. To learn more about reading nutrition labels, see ...

  15. Hypertension (High Blood Pressure)

    Science.gov (United States)

    ... over the years led to verification of the important role of high blood pressure—especially in concert with ... is specific for that person will be an important key to improving prevention, ... an international team of investigators, funded in part by the NIH, ...

  16. Gemini helium closed cycle cooling system

    Science.gov (United States)

    Lazo, Manuel; Galvez, Ramon; Rogers, Rolando; Solis, Hernan; Tapia, Eduardo; Maltes, Diego; Collins, Paul; White, John; Cavedoni, Chas; Yamasaki, Chris; Sheehan, Michael P.; Walls, Brian

    2008-07-01

    The Gemini Observatory presents the Helium Closed Cycle Cooling System that provides cooling capacity at cryogenic temperatures for instruments and detectors. It is implemented by running three independent helium closed cycle cooling circuits with several banks of compressors in parallel to continuously supply high purity helium gas to cryocoolers located about 100-120 meters apart. This poster describes how the system has been implemented, the required helium pressures and gas flow to reach cryogenic temperature, the performance it has achieved, the helium compressors and cryocoolers in use and the level of vibration the cryocoolers produce in the telescope environment. The poster also describes the new technology for cryocoolers that Gemini is considering in the development of new instruments.

  17. High pressure ceramic joint

    Science.gov (United States)

    Ward, Michael E.; Harkins, Bruce D.

    1993-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  18. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Planning, & Legislative Advisory Committees Jobs Contact Us FAQs Home » Health Information for the Public » Health Topics » High ... also may ask you to check readings at home or at other locations that have blood pressure ...

  19. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical Trials Links Related Topics Atherosclerosis DASH Eating Plan Overweight and Obesity Smoking and Your Heart ...

  20. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Health care providers diagnose this type of high blood pressure by reviewing readings in the office and readings taken anywhere else. ... The Heart Truth ® —a national heart disease awareness campaign for ...

  1. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... to check readings at home or at other locations that have blood pressure equipment and to keep ... office compared with readings taken in any other location. Health care providers diagnose this type of high ...

  2. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... provider usually takes 2–3 readings at several medical appointments to diagnose high blood pressure. Using the ... Researchers believe stress, which can occur during the medical appointment, causes white coat hypertension. Rate This Content: ...

  3. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs Contact Us FAQs Home » Health Information for the Public » Health Topics » High Blood Pressure » ...

  4. Bench experiments comparing simulated inspiratory effort when breathing helium-oxygen mixtures to that during positive pressure support with air

    Directory of Open Access Journals (Sweden)

    Martin Andrew R

    2012-10-01

    Full Text Available Abstract Background Inhalation of helium-oxygen (He/O2 mixtures has been explored as a means to lower the work of breathing of patients with obstructive lung disease. Non-invasive ventilation (NIV with positive pressure support is also used for this purpose. The bench experiments presented herein were conducted in order to compare simulated patient inspiratory effort breathing He/O2 with that breathing medical air, with or without pressure support, across a range of adult, obstructive disease patterns. Methods Patient breathing was simulated using a dual-chamber mechanical test lung, with the breathing compartment connected to an ICU ventilator operated in NIV mode with medical air or He/O2 (78/22 or 65/35%. Parabolic or linear resistances were inserted at the inlet to the breathing chamber. Breathing chamber compliance was also varied. The inspiratory effort was assessed for the different gas mixtures, for three breathing patterns, with zero pressure support (simulating unassisted spontaneous breathing, and with varying levels of pressure support. Results Inspiratory effort increased with increasing resistance and decreasing compliance. At a fixed resistance and compliance, inspiratory effort increased with increasing minute ventilation, and decreased with increasing pressure support. For parabolic resistors, inspiratory effort was lower for He/O2 mixtures than for air, whereas little difference was measured for nominally linear resistance. Relatively small differences in inspiratory effort were measured between the two He/O2 mixtures. Used in combination, reductions in inspiratory effort provided by He/O2 and pressure support were additive. Conclusions The reduction in inspiratory effort afforded by breathing He/O2 is strongly dependent on the severity and type of airway obstruction. Varying helium concentration between 78% and 65% has small impact on inspiratory effort, while combining He/O2 with pressure support provides an additive

  5. High pressure rinsing parameters measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cavaliere, E. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Fusetti, M. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Michelato, P. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Pagani, C. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy)]. E-mail: carlo.pagani@mi.infn.it; Pierini, P. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Paulon, R. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy); Sertore, D. [INFN Milano - LASA, Via F.lli Cervi 201, I-20090 Segrate (MI) (Italy)

    2006-07-15

    High pressure rinsing with ultra pure water jet is an essential step in the high field superconducting cavity production process. In this paper, we illustrate the experimental characterization of a HPR system, in terms of specific power and energy deposition on the cavity surfaces and on the damage threshold for niobium. These measurements are used to tentatively derive general rules for the optimization of the free process parameters (nozzle geometry, speeds and water pressure)

  6. Full Scale Thermo-hydraulic Simulation of a Helium-Helium Printed Circuit Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Injun; Hong, Sungyull; Bai, Cheolho; Shim, Jaesool [Yeungnam Univ., Gyeongsan (Korea, Republic of); Kim, Chansoo; Hong, Sungdeok; Kim, Minhwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    In this paper, the thermo-hydraulic full scale simulation is performed to study the temperature distributions, thermal stress, pressure drop and outlet temperature in a Helium-Helium printed circuit heat exchanger (PCHE) in a VHTR simulate helium loop. The entire PCHE is composed of 40 stacks of rectangular shaped micro-channels for helium gas [type A] (inlet temperature, 400 .deg. C) and 40 stacks of semi-ellipse shaped micro-channels for helium [type B] (inlet temperature, 300 .deg. C). The experimental result is compared to that of computer simulation, COMSOL multi-physics software. The Helium-Helium PCHE is considered a prototype of the newly developed PCHE by Korea Atomic Energy Research Institute (KAERI). The full scale thermo-hydraulic simulation was successfully performed to obtain temperature distribution, pressure drop and thermal stress in 40 sets of flow channel stacks in a helium-helium printed circuit heat exchanger in a VHTR simulate helium loop. We obtained a quite similar temperature distribution with the 3D measured infrared temperature distribution. To our knowledge, this is the first full scale numerical study on the PCHE, which considers all microchannels, that the convection effect on the outside surfaces of the PCHE is applied. The very high-temperature reactor (VHTR) or high-temperature gas-cooled reactor(HTGR) is a fourth-generation nuclear power reactor that uses the ceramic coated fuel, TRISO, in which the fission gas does not leak even at temperatures higher than 1600 .deg. C. The VHTR necessarily requires an intermediate loop composed of a hot gas duct (HGD), an intermediate heat exchanger (IHX) and a process heat exchanger (PHE). The IHX is one of the important components of VHTR system because the IHX transfers the 950 .deg. C of high temperature massive heat to a hydrogen production plant or power conversion unit at high system pressure.

  7. High-resolution infrared spectroscopy of HCN-Agn (n = 1-4) complexes solvated in superfluid helium droplets.

    Science.gov (United States)

    Stiles, Paul L; Miller, Roger E

    2007-08-01

    High-resolution infrared spectroscopy has been used to determine the structures, C-H stretching frequencies, and dipole moments of the HCN-Agn (n = 1-3) complexes formed in superfluid helium droplets. The HCN-Ag4 cluster was tentatively assigned based upon pick-up cell pressure dependencies and harmonic vibrational shift calculations. Ab initio and density functional theory calculations were used in conjunction with the high-resolution spectra to analyze the bonding nature of each cluster. All monoligated species reported here are bound through the nitrogen end of the HCN molecule. The HCN-Agn complexes are structurally similar to the previously reported HCN-Cun clusters, with the exception of the HCN-Ag binary complex. Although the interaction between the HCN and the Agn clusters follows the same trends as the HCN-Cun clusters, the more diffuse nature of the electrons surrounding the silver atoms results in a much weaker interaction.

  8. High-resolution dipole (e, e) study for optical oscillator strengths of helium

    Institute of Scientific and Technical Information of China (English)

    凤任飞; 杨炳忻; 武淑兰; 邢士林; 张芳; 钟志萍; 郭学哲; 徐克尊

    1996-01-01

    The optical oscillator strengths of helium have been studied by a high-resolution dipole (e, e) method on the recently built high-resolution fast-electron energy-loss spectrometer. The difficulties of optical measurement have been avoided and the experimental precision has been improved by using this method. The optical oscillator strength density spectrum corresponding to the 1S n’P transitions and ionization of helium has been measured in the energy loss range of 21 - 26 eV. And the same work corresponding to the autoionization resonance region has been done in energy loss ranges of 59-67 eV and 69-74 eV. The above results have also been compared with those of the previous work.

  9. Thermal Conductivity of Foam Glasses Prepared using High Pressure Sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    with open or closed pores. If only open pores exist, air is the dominating medium for the insulating effect. However, closed pores make it possible to trap gases inside the foam. The gas can be introduced either chemically, through foaming agents, or physically, by gas compression-decompression at high...... using helium, nitrogen, or argon. The sintering result in closed-porous body with high pressure bubbles. Subsequent reheating above the glass transition temperature resulted in an expansion of the bubbles. The entrapped gas composition was analysed by gas chromatography. Furthermore, we investigated how...

  10. FAST TRACK COMMUNICATION: Contrasting characteristics of sub-microsecond pulsed atmospheric air and atmospheric pressure helium-oxygen glow discharges

    Science.gov (United States)

    Walsh, J. L.; Liu, D. X.; Iza, F.; Rong, M. Z.; Kong, M. G.

    2010-01-01

    Glow discharges in air are often considered to be the ultimate low-temperature atmospheric pressure plasmas for numerous chamber-free applications. This is due to the ubiquitous presence of air and the perceived abundance of reactive oxygen and nitrogen species in air plasmas. In this paper, sub-microsecond pulsed atmospheric air plasmas are shown to produce a low concentration of excited oxygen atoms but an abundance of excited nitrogen species, UV photons and ozone molecules. This contrasts sharply with the efficient production of excited oxygen atoms in comparable helium-oxygen discharges. Relevant reaction chemistry analysed with a global model suggests that collisional excitation of O2 by helium metastables is significantly more efficient than electron dissociative excitation of O2, electron excitation of O and ion-ion recombination. These results suggest different practical uses of the two oxygen-containing atmospheric discharges, with air plasmas being well suited for nitrogen and UV based chemistry and He-O2 plasmas for excited atomic oxygen based chemistry.

  11. Experimental Determination of Spatial and Temporal Discharge Parameters for an Ambient Pressure Dielectric Barrier Discharge in Helium

    Science.gov (United States)

    Bures, Brian; Bourham, Mohamed

    2004-11-01

    Ambient pressure Dielectric Barrier Discharges (DBD's) are studied for a number of applications. Barrier discharges composed primarily of inert gases are potentially useful for the production of intense excimer light, sterilization of thermally sensitive materials and control of insects for quarantine. The neutral bremsstrahlung technique is used to determine spatial variations of electron density and electron temperature in a parallel plate, helium (99.9% by vol) dielectric barrier discharge operated at an average power density between 50 and 75 mW/cm^3. The applied frequency is varied between 2 kHz and 6 kHz. The time average electron density suggests a more intense discharge near the surface of the electrodes than the bulk of the discharge for all frequencies and power densities. When moving parallel to the electrodes, the electron temperature remains constant, while the electron density is constant within 20% of the average value. A monochromator tuned to a nitrogen ion line (391.4 nm) and a helium line (706.5 nm) has a more intense emission when the electrode is negatively biased.

  12. High-pressure creep tests

    Science.gov (United States)

    Bhattacharyya, S.; Lamoureux, J.; Hales, C.

    1986-01-01

    The automotive Stirling engine, presently being developed by the U.S. Department of Energy and NASA, uses high-pressure hydrogen as a working fluid; its long-term effects on the properties of alloys are relatively unknown. Hence, creep-rupture testing of wrought and cast high-temperature alloys in high-pressure hydrogen is an essential part of the research supporting the development of the Stirling cycle engine. Attention is given to the design, development, and operation of a 20 MPa hydrogen high-temperature multispecimen creep-rupture possessing high sensitivity. This pressure vessel allows for the simultaneous yet independent testing of six specimens. The results from one alloy, XF-818, are presented to illustrate how reported results are derived from the raw test data.

  13. Coherent diffractive imaging of single helium nanodroplets with a high harmonic generation source

    CERN Document Server

    Rupp, Daniela; Langbehn, Bruno; Sauppe, Mario; Zimmermann, Julian; Ovcharenko, Yevheniy; Möller, Thomas; Frassetto, Fabio; Poletto, Luca; Trabattoni, Andrea; Calegari, Francesca; Nisoli, Mauro; Sander, Katharina; Peltz, Christian; Vrakking, Marc J J; Fennel, Thomas; Rouzée, Arnaud

    2016-01-01

    Coherent diffractive imaging of individual free nanoparticles has opened novel routes for the in-situ analysis of their transient structural, optical, and electronic properties. So far, single-particle diffraction was assumed to be feasible only at extreme ultraviolet (XUV) and X-ray free-electron lasers, restricting this research field to large-scale facilities. Here we demonstrate single-shot imaging of isolated helium nanodroplets using XUV pulses from a femtosecond-laser driven high harmonic source. We obtain bright scattering patterns that provide access to the nanostructure's optical parameters. Moreover, the wide-angle scattering data enable us to uniquely identify hitherto unresolved prolate shapes of superfluid helium droplets. Our results mark the advent of single-shot gas-phase nanoscopy with lab-based short-wavelength pulses and pave the way to ultrafast coherent diffractive imaging with phase-controlled multicolor fields and attosecond pulses.

  14. Helium and hydrogen plasma waveguides for high-intensity laser channeling

    Science.gov (United States)

    Zgadzaj, Rafal Bogumil

    The results of cross polarized pump-probe experiments in preformed He plasma waveguides are reported. Pump and probe have same wavelength and duration of 800nm and 80fs respectively. Peak pump intensity is Iguided = 0.2x1018 W/cm2 ˜1000 Iprobe. Single shot probe spectra and mode profiles at the channel exit are discriminated from the pump with a polarization analyzer and captured at various relative time delays Deltat. Frequency-domain interference (FDI) between the probe and a weak depolarized component of the pump is observed for |Deltat| ≳ 100fs. Although the depolarized component is nearly undetectable through measurement of pump leakage alone, FDI sensitively reveals its substantially non-Gaussian structure. The possible depolarization mechanisms are analyzed. When probe is positioned at the leading edge of the pump, Deltat ≲ 0, its spectrum suffers a blue shift not measurable in the transmitted pump itself. The evidence suggests the channel interior is fully ionized and the partially formed channel ends are the origin of both depolarization and blue shift. A robust, pulsed, differentially-pumped plasma channel generation cell for high intensity guiding experiments has been developed. The design includes an axicon lens, windows for transverse interferometry, and permits injection of one or two different gases (main gas plus high Z seed gas) with several millisecond injection times and simultaneous 0.1ms pressure sensing resolution. Very well formed plasma waveguides have been formed in helium as well as hydrogen, at repeatable and well controlled pressures up to 1000Torr, with very uniform interior density, rapid density drop at boundaries, and very low exterior density. The possible danger associated with the use of large amounts of hydrogen was considered and a complex safety system was designed, constructed and used. Extensive analysis of channel profile reconstruction through transverse interferometry was performed. This includes an intuitive

  15. Cluster dynamics modeling of the effect of high dose irradiation and helium on the microstructure of austenitic stainless steels

    Science.gov (United States)

    Brimbal, Daniel; Fournier, Lionel; Barbu, Alain

    2016-01-01

    A mean field cluster dynamics model has been developed in order to study the effect of high dose irradiation and helium on the microstructural evolution of metals. In this model, self-interstitial clusters, stacking-fault tetrahedra and helium-vacancy clusters are taken into account, in a configuration well adapted to austenitic stainless steels. For small helium-vacancy cluster sizes, the densities of each small cluster are calculated. However, for large sizes, only the mean number of helium atoms per cluster size is calculated. This aspect allows us to calculate the evolution of the microstructural features up to high irradiation doses in a few minutes. It is shown that the presence of stacking-fault tetrahedra notably reduces cavity sizes below 400 °C, but they have little influence on the microstructure above this temperature. The binding energies of vacancies to cavities are calculated using a new method essentially based on ab initio data. It is shown that helium has little effect on the cavity microstructure at 300 °C. However, at higher temperatures, even small helium production rates such as those typical of sodium-fast-reactors induce a notable increase in cavity density compared to an irradiation without helium.

  16. Concentric-ring structures in an atmospheric pressure helium dielectric barrier discharge

    Institute of Scientific and Technical Information of China (English)

    Shang Wan-Li; Zhang Yuan-Tao; Wang De-Zhen; Sang Chao-Feng; Jiang shao-En; Yang Jia-Min; Liu shen-Ye; M.G.Kong

    2011-01-01

    This paper performs a numerical simulation of concentric-ring discharge structures within the scope of a two-dimensional diffusion-drift model at atmospheric pressure between two parallel circular electrodes covered with thin dielectric layers. With a relative high frequency the discharge structures present different appearances of ring structures within different radii in time due to the evolvement of the filaments. The spontaneous electron density distributions help understanding the formation and development of seff-organized discharge structures. During a cycle the electron avalanches are triggered by the electric field strengthened by the feeding voltage and the residual charged particles on the barrier surface deposited in the previous discharges. The accumulation of charges is shown to play a dominant role in the generation and annihilation of the discharge structures. Besides, the rings split and unify to bring and annihilate rings which form a new discharge structure.

  17. High pressure neon arc lamp

    Science.gov (United States)

    Sze, Robert C.; Bigio, Irving J.

    2003-07-15

    A high pressure neon arc lamp and method of using the same for photodynamic therapies is provided. The high pressure neon arc lamp includes a housing that encloses a quantity of neon gas pressurized to about 500 Torr to about 22,000 Torr. At each end of the housing the lamp is connected by electrodes and wires to a pulse generator. The pulse generator generates an initial pulse voltage to breakdown the impedance of the neon gas. Then the pulse generator delivers a current through the neon gas to create an electrical arc that emits light having wavelengths from about 620 nanometers to about 645 nanometers. A method for activating a photosensitizer is provided. Initially, a photosensitizer is administered to a patient and allowed time to be absorbed into target cells. Then the high pressure neon arc lamp is used to illuminate the target cells with red light having wavelengths from about 620 nanometers to about 645 nanometers. The red light activates the photosensitizers to start a chain reaction that may involve oxygen free radicals to destroy the target cells. In this manner, a high pressure neon arc lamp that is inexpensive and efficiently generates red light useful in photodynamic therapy is provided.

  18. Microscopic Deformation of Tungsten Surfaces by High Energy and High Flux Helium/Hydrogen Particle Bombardment with Short Pulses

    Science.gov (United States)

    Tokitani, Masayuki; Yoshida, Naoaki; Tokunaga, Kazutoshi; Sakakita, Hajime; Kiyama, Satoru; Koguchi, Haruhisa; Hirano, Yoichi; Masuzaki, Suguru

    The neutral beam injection facility in the National Institute of Advanced Industrial Science and Technology was used to irradiate a polycrystalline tungsten specimen with high energy and high flux helium and hydrogen particles. The incidence energy and flux of the beam shot were 25 keV and 8.8 × 1022 particles/m2 s, respectively. The duration of each shot was approximately 30 ms, with 6 min intervals between each shot. Surface temperatures over 1800 K were attained. In the two cases of helium irradiation, total fluence of either 1.5 × 1022 He/m2 or 4.0 × 1022 He/m2 was selected. In the former case, large sized blisters with diameter of 500 nm were densely observed. While, the latter case, the blisters were disappeared and fine nanobranch structures appeared instead. Cross-sectional observations using a transmission electron microscope (TEM) with the focused ion beam (FIB) technique were performed. According to the TEM image, after irradiation with a beam shot of total fluence 4.0 × 1022 He/m2 , there were very dense fine helium bubbles in the tungsten of sizes 1-50 nm. As the helium bubbles grew the density of the tungsten matrix drastically decreased as a result of void swelling. These effects were not seen in hydrogen irradiation case.

  19. Intermolecular Interactions at high pressure

    DEFF Research Database (Denmark)

    Eikeland, Espen Zink

    2016-01-01

    In this project high-pressure single crystal X-ray diffraction has been combined with quantitative energy calculations to probe the energy landscape of three hydroquinone clathrates enclosing different guest molecules. The simplicity of the hydroquinone clathrate structures together with their st......In this project high-pressure single crystal X-ray diffraction has been combined with quantitative energy calculations to probe the energy landscape of three hydroquinone clathrates enclosing different guest molecules. The simplicity of the hydroquinone clathrate structures together...... with their structural chemistry, controlled largely by subtle interactions between the host and the enclosed guest molecules, makes them attractive to study as model systems. Quantifying the numerous superimposed interactions in these clathrates will advance our understanding of more complex supramolecular aggregates....... High-pressure crystallography is the perfect method for studying intermolecular interactions, by forcing the molecules closer together. In all three studied hydroquinone clathrates, new pressure induced phase transitions have been discovered using a mixture of pentane and isopentane as the pressure...

  20. Design of an improved high cooling power 4 K GM cryocooler and helium compressor

    Science.gov (United States)

    Hao, X. H.

    2015-12-01

    High cooling power 4 K cryocoolers are in high demand given their broad applications in such fields as magnetic resonance imaging (MRI) and low temperature superconductors. ARS has recently designed and developed a high cooling power 4 K pneumatic-drive GM cryocooler which achieves a typical cooling power of 1.75 W/4.2 K. Steady input power of our newly developed helium compressor supplied to the cold head is 11.8 kW at 60 Hz. The operational speed of the cold head is 30 RPM. The effects of geometries and operational conditions on the cooling performance of this 4 K GM cryocooler are also experimentally tested.

  1. Concept Design for a High Temperature Helium Brayton Cycle with Interstage Heating and Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vernon, Milton E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pickard, Paul S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-12-01

    The primary metric for the viability of these next generation nuclear power plants will be the cost of generated electricity. One important component in achieving these objectives is the development of power conversion technologies that maximize the electrical power output of these advanced reactors for a given thermal power. More efficient power conversion systems can directly reduce the cost of nuclear generated electricity and therefore advanced power conversion cycle research is an important area of investigation for the Generation IV Program. Brayton cycles using inert or other gas working fluids, have the potential to take advantage of the higher outlet temperature range of Generation IV systems and allow substantial increases in nuclear power conversion efficiency, and potentially reductions in power conversion system capital costs compared to the steam Rankine cycle used in current light water reactors. For the Very High Temperature Reactor (VHTR), Helium Brayton cycles which can operate in the 900 to 950 C range have been the focus of power conversion research. Previous Generation IV studies examined several options for He Brayton cycles that could increase efficiency with acceptable capital cost implications. At these high outlet temperatures, Interstage Heating and Cooling (IHC) was shown to provide significant efficiency improvement (a few to 12%) but required increased system complexity and therefore had potential for increased costs. These scoping studies identified the potential for increased efficiency, but a more detailed analysis of the turbomachinery and heat exchanger sizes and costs was needed to determine whether this approach could be cost effective. The purpose of this study is to examine the turbomachinery and heat exchanger implications of interstage heating and cooling configurations. In general, this analysis illustrates that these engineering considerations introduce new constraints to the design of IHC systems that may require

  2. Hydraulic and thermal testing of different helium cooled irradiation rig models for the IFMIF High Flux Test Module

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Christine, E-mail: Christine.Klein@kit.edu; Arbeiter, Frederik; Martin, Thomas; Taubmann, Peter

    2016-03-15

    Highlights: • Two different single 1:1 irradiation rigs inside a mock-up container are presented. • Pressure drops in the single rig minichannels are measured. • Temperature fields are measured under different heater and flow conditions. • Predictability and reproducibility of the cooling flows can be shown. - Abstract: The hydraulic and thermal testing of two different irradiation rig models A and B, differing in the inlet nozzle design, bottom reflector length and steps inside a mock-up container is part of the HFTM validation activities which support the engineering design of the High Flux Test Module. The pressure drops for all models in the test section are measured for overall mass flow rates of 1–12 g/s and different absolute pressures of 1500 hPa and 2500 hPa at the pressure port at the inlet section. The pressure drops in different sections of the experiment and in the single rig minichannels are also measured with additional pressure ports on the surfaces of the rig models. Predictability and reproducibility of the cooling effects of the main cooling channels in the HFTM irradiation zone can be shown. Rig model B with a backward facing step is for high mass flow rates >∼7.5 g/s (this is the operation regime of the HFTM) superior to rig model A. Uniform perfusion of the multiple parallel minichannels of the irradiation rigs by helium gas is of importance to obtain uniform and predictable temperatures. Temperature fields under different heater and flow conditions have been measured.

  3. High Blood Pressure and Kidney Disease

    Science.gov (United States)

    ... Disease Mineral & Bone Disorder View All Content High Blood Pressure & Kidney Disease What is high blood pressure? Blood pressure is the force of blood ... million filtering units called nephrons. How does high blood pressure affect the kidneys? High blood pressure can ...

  4. Anxiety: A Cause of High Blood Pressure?

    Science.gov (United States)

    ... Conditions High blood pressure (hypertension) Can anxiety cause high blood pressure? Answers from Sheldon G. Sheps, M.D. Anxiety doesn't cause long-term high blood pressure (hypertension). But episodes of anxiety can cause dramatic, ...

  5. High Blood Pressure Often Undiagnosed, Untreated

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162996.html High Blood Pressure Often Undiagnosed, Untreated Half of mobile clinic patients ... that's often referred to as a "silent killer" -- high blood pressure, a new Canadian study reveals. High blood pressure, ...

  6. Effects of particle size, helium gas pressure and microparticle dose on the plasma concentration of indomethacin after bombardment of indomethacin-loaded poly-L-lactic acid microspheres using a Helios gun system.

    Science.gov (United States)

    Uchida, Masaki; Natsume, Hideshi; Kobayashi, Daisuke; Sugibayashi, Kenji; Morimoto, Yasunori

    2002-05-01

    We investigated the effects of the particle size of indomethacin-loaded poly-L-lactic acid microspheres (IDM-loaded PLA MS), the helium pressure used to accelerate the particles, and the bombardment dose of PLA MS on the plasma concentration of IDM after bombarding with IDM-loaded PLA MS of different particle size ranges, 20-38, 44-53 and 75-100 microm, the abdomen of hairless rats using the Helios gene gun system (Helios gun system). Using larger particles and a higher helium pressure, produced an increase in the plasma IDM concentration and the area under the plasma concentration-time curve (AUC) and resultant F (relative bioavailability with respect to intracutaneous injection) of IDM increased by an amount depending on the particle size and helium pressure. Although a reduction in the bombardment dose led to a decrease in C(max) and AUC, F increased on decreasing the bombardment dose. In addition, a more efficient F was obtained after bombarding with IDM-loaded PLA MS of 75-100 microm in diameter at each low dose in different sites of the abdomen compared with that after bolus bombardment with a high dose (dose equivalent). These results suggest that the bombardment injection of drug-loaded microspheres by the Helios gun system is a very useful tool for delivering a variety of drugs in powder form into the skin and systemic circulation.

  7. Vital Signs - High Blood Pressure

    Centers for Disease Control (CDC) Podcasts

    2012-10-02

    In the U.S., nearly one third of the adult population have high blood pressure, the leading risk factor for heart disease and stroke - two of the nation's leading causes of death.  Created: 10/2/2012 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 10/17/2012.

  8. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... any other location. Health care providers diagnose this type of high blood pressure by reviewing readings in the office and readings taken anywhere else. Researchers believe stress, which can occur during the medical appointment, causes white coat hypertension. Rate This Content: NEXT >> Updated: ...

  9. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Explore High Blood Pressure What Is... Other Names Causes Who Is at Risk Signs & Symptoms Diagnosis Treatments Prevention Living With Clinical Trials Links Related Topics Atherosclerosis DASH Eating Plan Overweight and Obesity Smoking and Your Heart Stroke Send a link ...

  10. High Pressure Treatment in Foods.

    Science.gov (United States)

    Bello, Edwin Fabian Torres; Martínez, Gerardo González; Ceberio, Bernadette F Klotz; Rodrigo, Dolores; López, Antonio Martínez

    2014-08-19

    High hydrostatic pressure (HHP), a non-thermal technology, which typically uses water as a pressure transfer medium, is characterized by a minimal impact on food characteristics (sensory, nutritional, and functional). Today, this technology, present in many food companies, can effectively inactivate bacterial cells and many enzymes. All this makes HHP very attractive, with very good acceptance by consumers, who value the organoleptic characteristics of products processed by this non-thermal food preservation technology because they associate these products with fresh-like. On the other hand, this technology reduces the need for non-natural synthetic additives of low consumer acceptance.

  11. High Pressure Treatment in Foods

    Directory of Open Access Journals (Sweden)

    Edwin Fabian Torres Bello

    2014-08-01

    Full Text Available High hydrostatic pressure (HHP, a non-thermal technology, which typically uses water as a pressure transfer medium, is characterized by a minimal impact on food characteristics (sensory, nutritional, and functional. Today, this technology, present in many food companies, can effectively inactivate bacterial cells and many enzymes. All this makes HHP very attractive, with very good acceptance by consumers, who value the organoleptic characteristics of products processed by this non-thermal food preservation technology because they associate these products with fresh-like. On the other hand, this technology reduces the need for non-natural synthetic additives of low consumer acceptance.

  12. High pressure rinsing system comparison

    Energy Technology Data Exchange (ETDEWEB)

    D. Sertore; M. Fusetti; P. Michelato; Carlo Pagani; Toshiyasu Higo; Jin-Seok Hong; K. Saito; G. Ciovati; T. Rothgeb

    2007-06-01

    High pressure rinsing (HPR) is a key process for the surface preparation of high field superconducting cavities. A portable apparatus for the water jet characterization, based on the transferred momentum between the water jet and a load cell, has been used in different laboratories. This apparatus allows to collected quantitative parameters that characterize the HPR water jet. In this paper, we present a quantitative comparison of the different water jet produced by various nozzles routinely used in different laboratories for the HPR process

  13. Creep behavior of alloy 617 in high temperature air and helium environments-effect of oxidation damage

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Chang Heui; Kim, Sung Hwan [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Sah, Injin; Kim, Dae Jong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The creep behavior of a nickel-base superalloy, Alloy 617, which is considered as a candidate material for the very high temperature gas cooled reactor, was studied. Creep rupture tests were carried out at 800°C, 900°C and 1000°C in static and flowing helium environments as well as in air. Creep rupture life in static helium was longer than that in air, while it was shorter in flowing helium environments. Microstructure observation of the creep tested specimens showed that the shorter creep rupture life in flowing helium was associated with the thicker oxide layer, greater decarburization depth, and deeper internal oxidation happened during the creep tests. The degree of such oxidation damage was quantified for the creep tested specimens and correlated with the creep rupture life in different environments.

  14. Mechanism of bullet-to-streamer transition in water surface incident helium atmospheric pressure plasma jet (APPJ)

    Science.gov (United States)

    Yoon, Sung-Young; Kim, Gon-Ho; Kim, Su-Jeong; Bae, Byeongjun; Kim, Seong Bong; Ryu, Seungmin; Yoo, Suk Jae

    2016-09-01

    The mechanism of bullet to streamer transition of helium-APPJ bullet on the electrolyte surface was investigated. The APPJ was discharged in pin-to-ring DBD reactor system with helium gas by applying the ac-driven voltage at a frequency of 10 kHz. The water evaporation was controlled via saline temperature. The temporal- and 2-dimensional spatially- resolved plasma properties are monitored by optical diagnostics. During the APPJ bullet propagation from reactor to electrolyte surface, the transition of bullet from streamer was recognized from the high speed image, hydrogen beta emission line, and bullet propagation speed. The He metastable species density profiles from the tunable diode laser absorption spectroscopy (TDLAS) showed the metastable lost the energy near electrolyte surface. It is found that the bullet transited to streamer when the water fraction reached to 29%. This can be fascinating result to study the plasma physics liquid surface, non-fixed boundary. Acknowledgements: This work was partly supported by R&D Program of `Plasma Advanced Technology for Agriculture and Food (Plasma Farming)' through the National Fusion Research Institute of Korea (NFRI) funded by the Government fund was carried out as part.

  15. Pressure - Density Isotherms of HELIUM-3 Gas Below 1.3 K.

    Science.gov (United States)

    Cameron, James Allen

    The second virial coefficient of He('3) gas and the absolute temperature of the gas were determined at five different temperatures below 1.3 K. The technique used involved measuring pressure and density simultaneously at different points along on isotherm and using the virial equation to determine the temperature and the second virial coefficient. The results are in good agreement with empirical calculations of the second virial coefficient which are based on measurements made at higher temperatures. The measurements of temperature, while only known to within (+OR-)1.5 mK, confirm the widespread belief that the T(,62) temperature scale is in error by several mK. Pressure and density were measured in-situ, using superconducting microwave cavities. These eliminate many sources of error which have in the past made measurements inaccurate below 1.5 K. The density and pressure could be related to changes in the resonant frequencies of the cavities. The frequency of one cavity, which contained the He('3) gas was proportional to the dielectric constant of the gas. The Clausius-Mossotti relationship was used to determine the density as a function of the dielectric constant. The pressure was measured using a reentrant cavity with a flexible diaphragm forming one end wall. The pressure of the gas flexed this diaphragm, changing the frequency of the cavity. A room temperature mercury manometer was used to provide a frequency vs. pressure calibration of this cavity.

  16. High Blood Pressure: Unique to Older Adults

    Science.gov (United States)

    ... our e-newsletter! Aging & Health A to Z High Blood Pressure Hypertension Unique to Older Adults This section provides ... Pressure Targets are Different for Very Old Adults High blood pressure (also called hypertension) increases your chance of having ...

  17. High pressure processing of meat

    DEFF Research Database (Denmark)

    Grossi, Alberto; Christensen, Mette; Ertbjerg, Per

    in the myofibrillar protein pattern and HP-induced change in activity of cathepsin B and L were investigated. Results: In this study we showed that HP treatment of pork meat emulsion, ranging from 0.1 to 800 MPa, induced protein gel formation as shown by the increased Young’s modulus (Fig.1). Analysis of SDS...... the rheological properties of pork meat batters by inducing formation of protein gels. HP induced protein gels are suggested to be formed by high molecular weight myofibrillar protein aggregates and by peptides formed by lysosomal enzyme-induced cleavage of myofibrillar proteins. Perspectives: The data presented......Abstract Background: The research of high pressure (HP) processing of meat based foods needs to address how pressure affects protein interactions, aggregation and/or gelation. The understanding of the gel forming properties of myofibrillar components is fundamental for the development of muscle...

  18. High pressure effects on fruits and vegetables

    NARCIS (Netherlands)

    Timmermans, R.A.H.; Matser, A.M.

    2016-01-01

    The chapter provides an overview on different high pressure based treatments (high pressure pasteurization, blanching, pressure-assisted thermal processing, pressure-shift freezing and thawing) available for the preservation of fruits and vegetable products and extending their shelf life. Pressure t

  19. High pressure effects on fruits and vegetables

    NARCIS (Netherlands)

    Timmermans, R.A.H.; Matser, A.M.

    2016-01-01

    The chapter provides an overview on different high pressure based treatments (high pressure pasteurization, blanching, pressure-assisted thermal processing, pressure-shift freezing and thawing) available for the preservation of fruits and vegetable products and extending their shelf life. Pressure

  20. Questions and Answers about High Blood Pressure

    Science.gov (United States)

    ... checked out by a doctor. Am I at risk for high blood pressure? Anyone can develop high blood pressure. But there are several factors that increase your risk: Being overweight or obese Not ... if I have high blood pressure? High blood pressure is often called "the silent ...

  1. High Blood Pressure (Hypertension) (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old High Blood Pressure (Hypertension) KidsHealth > For Parents > High Blood Pressure (Hypertension) A ... posture, and medications. continue Long-Term Effects of High Blood Pressure When someone has high blood pressure, the heart ...

  2. High Blood Pressure (Hypertension) (For Parents)

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old High Blood Pressure (Hypertension) KidsHealth > For Parents > High Blood Pressure (Hypertension) ... posture, and medications. continue Long-Term Effects of High Blood Pressure When someone has high blood pressure, the heart ...

  3. submitter Superconducting instrumentation for high Reynolds turbulence experiments with low temperature gaseous helium

    CERN Document Server

    Pietropinto, S; Baudet, C; Castaing, B; Chabaud, B; Gagne, Y; Hébral, B; Ladam, Y; Lebrun, P; Pirotte, O; Roche, P

    2003-01-01

    Turbulence is of common experience and of high interest for industrial applications, despite its physical grounds is still not understood. Cryogenic gaseous helium gives access to extremely high Reynolds numbers (Re). We describe an instrumentation hosted in CERN, which provides a 6 kW @ 4.5 K helium refrigerator directly connected to the experiment. The flow is a round jet; the flow rates range from 20 g/s up to 260 g/s at 4.8 K and about 1.2 bar, giving access to the highest controlled Re flow ever developed. The experimental challenge lies in the range of scales which have to be investigated: from the smallest viscous scale η, typically 1 μm at Re=107 to the largest L∼10 cm. The corresponding frequencies: f=v/η can be as large as 1 MHz. The development of an original micrometric superconducting anemometer using a hot spot and its characteristics will be discussed together with its operation and the perspectives associated with superconducting anemometry.

  4. Corrosion of high temperature alloys in the coolant helium of a gas cooled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cabet, C.; Terlain, A. [Service de la Corrosion et du Comportement des Materiaux dans leur Environnement, DEN/DPC - CEA/Saclay, Gif sur Yvette (France); Monnier, A. [Lab. de Genie Electrique de Paris, Plateau du Moulon, Gif sur Yvette (France)

    2004-07-01

    The corrosion of structural alloys in gas cooled reactor environment appears to be a critical issue. The coolant helium proved to contain impurities mainly H{sub 2}, H{sub 2}O, CO, and CH{sub 4} in the microbar range that interact with metallic materials at high temperature. Surface scale formation, bulk carburisation and/or decarburisation can occur, depending on the gas chemistry, the alloy composition and the temperature. These structural transformations can notably influence the component mechanical properties. A short review of the literature on the topic is first given. Corrosion tests with high chromium alloys and a Mo-based alloy were carried out at 750 C in a purposely-designed facility under simulated GCR helium. The first, rather short term, results showed that the Mo-based alloy was inert while the others alloys oxidised during at least 900 hours. The alloy with the higher Al and Ti contents exhibited poor oxidation resistance impeding its use as structural material without further investigations. (orig.)

  5. High aspect ratio AFM Probe processing by helium-ion-beam induced deposition.

    Science.gov (United States)

    Onishi, Keiko; Guo, Hongxuan; Nagano, Syoko; Fujita, Daisuke

    2014-11-01

    A Scanning Helium Ion Microscope (SHIM) is a high resolution surface observation instrument similar to a Scanning Electron Microscope (SEM) since both instruments employ finely focused particle beams of ions or electrons [1]. The apparent difference is that SHIMs can be used not only for a sub-nanometer scale resolution microscopic research, but also for the applications of very fine fabrication and direct lithography of surfaces at the nanoscale dimensions. On the other hand, atomic force microscope (AFM) is another type of high resolution microscopy which can measure a three-dimensional surface morphology by tracing a fine probe with a sharp tip apex on a specimen's surface.In order to measure highly uneven and concavo-convex surfaces by AFM, the probe of a high aspect ratio with a sharp tip is much more necessary than the probe of a general quadrangular pyramid shape. In this paper we report the manufacture of the probe tip of the high aspect ratio by ion-beam induced gas deposition using a nanoscale helium ion beam of SHIM.Gas of platinum organic compound was injected into the sample surface neighborhood in the vacuum chamber of SHIM. The decomposition of the gas and the precipitation of the involved metal brought up a platinum nano-object in a pillar shape on the normal commercial AFM probe tip. A SHIM system (Carl Zeiss, Orion Plus) equipped with the gas injection system (OmniProbe, OmniGIS) was used for the research. While the vacuum being kept to work, we injected platinum organic compound ((CH3)3(CH3C5H4)Pt) into the sample neighborhood and irradiated the helium ion beam with the shape of a point on the apex of the AFM probe tip. It is found that we can control the length of the Pt nano-pillar by irradiation time of the helium ion beam. The AFM probe which brought up a Pt nano-pillar is shown in Figure 1. It is revealed that a high-aspect-ratio Pt nano-pillar of ∼40nm diameter and up to ∼2000 nm length can be grown. In addition, for possible heating

  6. Concentric-Ring Patterns in a Helium Dielectric Barrier Discharge at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    SHANG Wan-Li; WANG De-Zhen

    2007-01-01

    We perform the theoretical simulation of the concentric-ring patterns between two parallel electrodes covered with thin dielectric layers within the scope of a two-dimensional diffusion-drift model at atmospheric pressure. The time evolution of the discharge patterns is studied and the concentric-ring patterns with different radii shift alternately. The spatial-temporal evolution of electron density in a cycle at different time scales is performed.

  7. High pressure single crystal and powder XRD study for neighborite

    Science.gov (United States)

    Liu, H.

    2016-12-01

    After Murakami et al. (2004) identified the post-perovskite (ppv) phase transition in MgSiO3 perovskite (pv) at pressures and temperatures consistent with the onset of Earth's D" layer, lots of post-perovskite type phase transitions were founded in other similar systems. These discoveries provided a better understanding of heterogeneous structures and seismic anisotropy observed in the controversial region of the lower mantle. With previous experimental evidence showing the analogue system of neighborite NaMgF3 will transform from pv to ppv at 30 GPa, we performed high quality single crystal XRD experiment, which led to a more precise structure determination. Using helium as pressure medium, one metastable low symmetric phase before the pv-ppv structure transition was discovered, whose total energy was calculated as well. The comparison between single crystal and powder XRD data will be presented, and potential application will be discussed.

  8. Pressure-broadening of water transitions near 7180 cm(-1) by helium isotopes.

    Science.gov (United States)

    Campbell, H M; Havey, D K

    2013-05-15

    In this study, pressure-broadening parameters for several H2O transitions near 7180 cm(-1) are obtained which describe collisions with (3)He and (4)He. The sensitivity of those parameters to choice of theoretical line profile (Galatry vs. Voigt) is investigated. H2O is an important species in atmospheric chemistry and astronomy. Because of this, basic fundamental research, which explores the nature of the H2O spectrum in the presence of different gases of varying physical properties, can provide useful reference data which can be applied in the fields of atmospheric and planetary remote sensing. Measurements were made using an intensity-modulated laser photoacoustic spectrometer. Results from the present work show that Galatry line profiles, with a constrained narrowing parameter, more accurately describe experimental spectra than Voigt profiles over a wide range of experimental pressure conditions. Average pressure-broadening parameters were found to be 0.0216 cm(-1)/atm and 0.0209 cm(-1)/atm for H2O in (3)He and (4)He, respectively, and were compared to a literature model for the mass-dependence of line broadening. Specific values were obtained for each transition with nominal combined uncertainties of 2-6%.

  9. Characteristics in the jet region of helium radio-frequency atmospheric-pressure glow discharge with array generators

    Directory of Open Access Journals (Sweden)

    Zhi-Bin Wang

    2015-09-01

    Full Text Available The two-dimensional spatially extended atmospheric plasma arrays by many parallel radio-frequency glow discharge plasma jets packed densely, represent a feature option of large-scale low-temperature atmospheric plasma technologies with distinct capability of directed delivery of reactive species and good insusceptibility to sample variations. However, it is still a challenge to form plasma jet with large area of uniform active species on a downstream substrate due to the complex interactions between individual jets. This paper proposes to numerically study the strategy and mechanism of control/modulation for the array discharge to produce two-dimensional plasma uniformity in the downstream working area. In this work, a two dimensional fluid model is employed to investigate the characteristics in the jet region of helium radio-frequency atmospheric-pressure glow discharge (RF APGD with array generators. The influences of upstream discharge characteristics, gas flow and their cooperative effects on the distribution of species densities, gas temperatures and the uniformity of active species in the material treating area is studied, and the essential strategy for the modulation method is acquired. The results will be significant for deep understanding of coupling behaviors of multiple plasma plumes in the RF APGD array and applications of the technology.

  10. Space and time structure of helium pulsed surface-wave discharges at intermediate pressures (5-50 Torr)

    Science.gov (United States)

    Hamdan, Ahmad; Valade, Fabrice; Margot, Joëlle; Vidal, François; Matte, Jean-Pierre

    2017-01-01

    In this paper, the ignition and development of a plasma created by pulsed surface wave discharges (PSWDs) was experimentally investigated using time-resolved imaging techniques and optical spectroscopy in helium at intermediate gas pressures between 5 and 50 Torr. We found that the ionization front moves at a few km s-1 during the ignition phase and decreases to hundreds of m s-1 after only some tens of µs. Once the plasma has reached a sufficient length, a standing wave pattern is observed in the light emission of the discharge. We attribute its formation to the reflection of the surface wave on the ionization front, which results in a pattern of nodes and antinodes. We have also determined the time and space evolution of the gas temperature. It is shown that the gas temperature increases from the room temperature value to a plateau at several hundreds of degrees over a short time (typically 100 µs). These results supports those obtained by light emission imaging and also show that the standing wave pattern does not affect the gas temperature.

  11. Development of gas cooled reactors and experimental setup of high temperature helium loop for in-pile operation

    Energy Technology Data Exchange (ETDEWEB)

    Miletić, Marija, E-mail: marija_miletic@live.com [Czech Technical University in Prague, Prague (Czech Republic); Fukač, Rostislav, E-mail: fuk@cvrez.cz [Research Centre Rez Ltd., Rez (Czech Republic); Pioro, Igor, E-mail: Igor.Pioro@uoit.ca [University of Ontario Institute of Technology, Oshawa (Canada); Dragunov, Alexey, E-mail: Alexey.Dragunov@uoit.ca [University of Ontario Institute of Technology, Oshawa (Canada)

    2014-09-15

    Highlights: • Gas as a coolant in Gen-IV reactors, history and development. • Main physical parameters comparison of gas coolants: carbon dioxide, helium, hydrogen with water. • Forced convection in turbulent pipe flow. • Gas cooled fast reactor concept comparisons to very high temperature reactor concept. • High temperature helium loop: concept, development, mechanism, design and constraints. - Abstract: Rapidly increasing energy and electricity demands, global concerns over the climate changes and strong dependence on foreign fossil fuel supplies are powerfully influencing greater use of nuclear power. In order to establish the viability of next-generation reactor concepts to meet tomorrow's needs for clean and reliable energy production the fundamental research and development issues need to be addressed for the Generation-IV nuclear-energy systems. Generation-IV reactor concepts are being developed to use more advanced materials, coolants and higher burn-ups fuels, while keeping a nuclear reactor safe and reliable. One of the six Generation-IV concepts is a very high temperature reactor (VHTR). The VHTR concept uses a graphite-moderated core with a once-through uranium fuel cycle, using high temperature helium as the coolant. Because helium is naturally inert and single-phase, the helium-cooled reactor can operate at much higher temperatures, leading to higher efficiency. Current VHTR concepts will use fuels such as uranium dioxide, uranium carbide, or uranium oxycarbide. Since some of these fuels are new in nuclear industry and due to their unknown properties and behavior within VHTR conditions it is very important to address these issues by investigate their characteristics within conditions close to those in VHTRs. This research can be performed in a research reactor with in-pile helium loop designed and constructed in Research Center Rez Ltd. One of the topics analyzed in this article are also physical characteristic and benefits of gas

  12. Pressure Drop in Cyclone Separator at High Pressure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    For the design of pressurized circulating fluidized beds, experiments were conducted in a small cyclone with 120 mm in diameter and 300 mm in height at high pressures and at atmospheric temperatures. Influence of air leakage from the stand pipe into the cyclone was specially focused. A semi-empirical model was developed for the predic tion of the pressure drop of the cyclone separator at different operate pressures with the effect of air leakage and inlet solid loading. The operate pressure, air leakage and inlet solid loading act as significant roles in cyclone pressure drop. The pressure drop increases with the increasing of pressure and decreases with the increasing of the flow rate of air leakage from the standpipe and with the increasing of the inlet solid loading.

  13. Design of helium-driven MHD disk generators with high performance

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, H.; Kabashima, S.; Yamasaki, H.; Shioda, S. (Tokyo Inst. of Tech. (JP). Dept. of Energy Sciences)

    1990-01-01

    A design method for helium-driven MHD disk generator channels including boundary-layer behavior is proposed. In this method, the main flow in the channels is one-dimensionally treated, taking account of the concept of effective cross-sectional area of the channels. This effective area is determined by solving two-dimensional boundary-layer equations. Using this method, the generator channels on various scales are numerically designed under the condition of fully ionized seed. Furthermore, the scale effects of the boundary layer on the area ratio, heat loss and adiabatic efficiency of the generators are examined. It is found from this study that a generator having a thermal input of more than 100 MW is required to achieve high enthalpy extraction with high adiabatic efficiency (more than 65%). (author).

  14. Influence of the ionization-energy losses of high-energy bismuth ions on the development of helium blisters in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Reutov, V. F., E-mail: reutov@jinr.ru; Dmitriev, S. N.; Sohatsky, A. S. [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (Russian Federation); Zaluzhnyi, A. G. [National Research Nuclear University “MEPhi” (Moscow Engineering Physics Institute) (Russian Federation)

    2015-10-15

    Understanding the behavior of helium in solids under conditions of intense ionizing radiation is of particular interest in solving many problems of nuclear, fusion, and space materials science and also in microelectronics. The observed effect of suppressing the formation of helium blisters on the surface of helium ion-doped silicon as a result of irradiation with high-energy bismuth ions is reported in this publication. It is suggested that a possible decrease in the concentration of helium atoms in silicon is due to their radiationinduced desorption from the area of doping in terms of the high-impact ionization of bismuth ions.

  15. Study of a new direct current atmospheric pressure glow discharge in helium

    Energy Technology Data Exchange (ETDEWEB)

    Gielniak, B. [University of Hamburg, Institute for Inorganic and Applied Chemistry, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Fiedler, T. [Johannes Gutenberg-University Mainz, Institute for Inorganic and Analytical Chemistry, Duesbergweg 10-14, 55128 Mainz (Germany); Broekaert, J.A.C., E-mail: jose.broekaert@chemie.uni-hamburg.de [University of Hamburg, Institute for Inorganic and Applied Chemistry, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany)

    2011-01-15

    In this study a new DC-APGD operated in He was developed and characterized. The discharge is operated at 0.9 kV and about 25-35 mA and at a gas flow of 100 ml/min. The source was spectroscopically studied and parameters such as the rotational temperature (T{sub rot}), the excitation temperature (T{sub exc}), the ionization temperature (T{sub ion}) and the electron number density (n{sub e}) were determined. The current-voltage characteristic of the source was studied as well. At optimized conditions the discharge operates in the normal region of the current-voltage characteristic. Rotational and excitation temperatures determined with the use of OH band and Fe I lines as thermometric species were of the order of about 900-1200 and 4500-5500 K, respectively. This indicates that despite of the atmospheric pressure, the discharge is not in LTE. Spatially resolved temperature measurements were performed with axial as well as radial resolution and showed relatively flat profiles. Axially resolved emission intensity profiles for several species such as H, N{sub 2}, N{sub 2}{sup +}, OH, He and Hg were determined. It also was found that H{sub 2} introduced into the He by electrolysis of acid solutions such as in ECHG considerably increases the spectroscopically measured gas temperatures but decreases the analyte line intensities, as shown for Hg.

  16. Characteristics of an activated carbon monolith for a helium adsorption compressor

    NARCIS (Netherlands)

    Lozano-Castello, D.; Jorda-Beneyto, M.; Cazorla-Amoros, D.; Linares-Solano, A.; Burger, J.F.; Brake, ter H.J.M.; Holland, H.J.

    2010-01-01

    An activated carbon monolith (ACM) with a high helium adsorption/desorption capacity, high density, low pressure drop, low thermal expansion and good mechanical properties was prepared and applied successfully in a helium adsorption compressor as a part of a 4.5 K sorption cooler. The activated carb

  17. High-pressure microhydraulic actuator

    Science.gov (United States)

    Mosier, Bruce P [San Francisco, CA; Crocker, Robert W [Fremont, CA; Patel, Kamlesh D [Dublin, CA

    2008-06-10

    Electrokinetic ("EK") pumps convert electric to mechanical work when an electric field exerts a body force on ions in the Debye layer of a fluid in a packed bed, which then viscously drags the fluid. Porous silica and polymer monoliths (2.5-mm O.D., and 6-mm to 10-mm length) having a narrow pore size distribution have been developed that are capable of large pressure gradients (250-500 psi/mm) when large electric fields (1000-1500 V/cm) are applied. Flowrates up to 200 .mu.L/min and delivery pressures up to 1200 psi have been demonstrated. Forces up to 5 lb-force at 0.5 mm/s (12 mW) have been demonstrated with a battery-powered DC-DC converter. Hydraulic power of 17 mW (900 psi@ 180 uL/min) has been demonstrated with wall-powered high voltage supplies. The force and stroke delivered by an actuator utilizing an EK pump are shown to exceed the output of solenoids, stepper motors, and DC motors of similar size, despite the low thermodynamic efficiency.

  18. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... blood pressure test is easy and painless and can be done in a health care provider’s office ... severity of your blood pressure, he or she can order additional tests to determine if your blood ...

  19. Managing Stress to Control High Blood Pressure

    Science.gov (United States)

    ... Aneurysm More Managing Stress to Control High Blood Pressure Updated:Jan 10,2017 The importance of stress ... content was last reviewed October 2016. High Blood Pressure • Home • Get the Facts About HBP • Know Your ...

  20. Avoid the Consequences of High Blood Pressure

    Science.gov (United States)

    ... Thromboembolism Aortic Aneurysm More Avoid the Consequences of High Blood Pressure Infographic Updated:Oct 31,2016 View a downloadable version of this infographic High Blood Pressure • Home • Get the Facts About HBP • Know Your ...

  1. High Blood Pressure: Keep the Beat Recipes

    Science.gov (United States)

    ... of this page please turn Javascript on. Feature: High Blood Pressure Keep the Beat Recipes Past Issues / Fall 2011 ... 65 million American adults—one in three—with high blood pressure, you have probably heard the advice, "watch your ...

  2. High blood pressure and eye disease

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000999.htm High blood pressure and eye disease To use the sharing features on this page, please enable JavaScript. High blood pressure can damage blood vessels in the retina . The ...

  3. Preliminary Study on Insulating Design of Electrical Device in Helium for High Temperature Gas-Cooled Reactor%高温气冷堆氦气环境中电气设备绝缘设计研究

    Institute of Scientific and Technical Information of China (English)

    于晓丽; 杨小勇; 周世新; 王捷

    2011-01-01

    应用巴申定律研究了氦气的电气击穿特性,并与空气的绝缘特性进行比较.以高温气冷堆氦气透平发电系统电机腔室的设计参数为例,结合氦气的巴申曲线,对氦气条件下气体压力和极间距离的关系进行深入探讨,并提出氦气环境中电气设备绝缘设计需关注的问题.研究结果表明,氦气最小击穿电压为150~200 V,绝缘特性较差,电气设备绝缘结构设计应考虑氦气环境压力的影响,现有针对压水堆电站电气设备绝缘结构的验收准则和试验方法并不完全适用于氦气环境.%The breakdown performance of helium was studied by Paschen law, comparing with air. Combined with the operation parameter of generator in gas turbine coupled with high temperature gas-cooled reactor and the Paschen curve of helium, the relationship between pressure and insulating structure was discussed. The key points for the insulation design of the electrical device in helium were presented. The results show that the insulation performance for helium which lowest breakdown potentials is 150-200 V is much worse than that of air. The existing test and inspect guidelines of the insulation structure for the pressure water reactor can't be used for the helium. High permeability for helium may be an important reason to destroy the insulation structure.

  4. Corrosion and Creep of Candidate Alloys in High Temperature Helium and Steam Environments for the NGNP

    Energy Technology Data Exchange (ETDEWEB)

    Was, Gary; Jones, J. W.

    2013-06-21

    This project aims to understand the processes by which candidate materials degrade in He and supercritical water/steam environments characteristic of the current NGNP design. We will focus on understanding the roles of temperature, and carbon and oxygen potential in the 750-850 degree C range on both uniform oxidation and selective internal oxidation along grain boundaries in alloys 617 and 800H in supercritical water in the temperature range 500-600 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature rang 750-850 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature range 750-850 degree C over a range of oxygen and carbon potentials in helium. Combined, these studies wil elucidate the potential high damage rate processes in environments and alloys relevant to the NGNP.

  5. Two modes of interfacial pattern formation by atmospheric pressure helium plasma jet-ITO interactions under positive and negative polarity

    Science.gov (United States)

    Liu, Zhijie; Liu, Dingxin; Xu, Dehui; Cai, Haifeng; Xia, Wenjie; Wang, Bingchuan; Li, Qiaosong; Kong, Michael G.

    2017-05-01

    In this paper, we report the observation of an interfacial pattern formation on the ITO surface by atmospheric pressure helium plasma jet-ITO interactions. By changing the voltage polarity of positive and negative pulses, the interfacial phenomenon displays two different pattern modes, i.e. a double ring pattern with a combination of homogeneous and filamentous modes as well as a single ring pattern with a homogeneous mode. The reasons may mainly be attributed to the spread of a radially outward traveling surface ionization wave that would cause electric field distributions and charge accumulations on the ITO surface. The spatial-temporal distribution of \\text{N}2+≤ft({{B}2}{\\sum}\\text{u}+\\right) , He(3s3S), and O(3p5P) emissions are diagnosed to better understand the formation mechanism and the differences of plasma jet patterns under positive and negative polarities. Results show that the distribution of \\text{N}2+≤ft({{B}2}{\\sum}\\text{u}+\\right) emission is the main contributor for generating the filament structure in a double ring pattern for positive polarity, the homogeneous mode pattern mainly depends on the distribution of O(3p5P) emission for positive and negative polarity. Additionally, in order to further systematically understand the behaviors of plasma jet patterns, some parametric results, such as behaviors versus pulse peak voltage, dielectric material, pulse repetition rate, and flow rate are investigated. Some interesting phenomena and additional insights for the plasma jet pattern are found with different parametric conditions. This study might help to better understand effects of plasma jets in interaction with surfaces, or its application in the medical sector.

  6. Creep Crack Growth Behavior of Alloys 617 and 800H in Air and Impure Helium Environments at High Temperatures

    Science.gov (United States)

    Grierson, D. S.; Cao, G.; Brooks, P.; Pezzi, P.; Glaudell, A.; Kuettel, D.; Fischer, G.; Allen, T.; Sridharan, K.; Crone, W. C.

    2016-11-01

    The environmental degradation of intermediate heat exchanger (IHX) materials in impure helium has been identified as an area with major ramifications on the design of very high-temperature reactors (VHTR). It has been reported that in some helium environments, non-ductile failure is a significant failure mode for Alloy 617 with long-term elevated-temperature service. Non-ductile failure of intermediate exchangers can result in catastrophic consequences; unfortunately, the knowledge of creep crack initiation and creep crack growth (CCG) in candidate alloys is limited. Current codes and code cases for the candidate alloys do not provide specific guidelines for effects of impure helium on the high-temperature behavior. The work reported here explores creep crack growth characterization of Alloy 617 and Alloy 800H at elevated temperatures in air and in impure helium environments, providing information on the reliability of these alloys in VHTR for long-term service. Alloy 617 was found to exhibit superior CCG resistance compared to Alloy 800H. For Alloy 617 tested at 973 K (700 °C), a notable increase in the resistance to crack growth was measured in air compared to that measured in the helium environment; CCG results for Alloy 800H suggest that air and helium environments produce similar behavior. Testing of grain boundary-engineered (GBE) Alloy 617 samples revealed that, although the technique produces superior mechanical properties in many respects, the GBE samples exhibited inferior resistance to creep crack growth compared to the other Alloy 617 samples tested under similar conditions. Grain size is noted as a confounding factor in creep crack growth resistance.

  7. Creep Crack Growth Behavior of Alloys 617 and 800H in Air and Impure Helium Environments at High Temperatures

    Science.gov (United States)

    Grierson, D. S.; Cao, G.; Brooks, P.; Pezzi, P.; Glaudell, A.; Kuettel, D.; Fischer, G.; Allen, T.; Sridharan, K.; Crone, W. C.

    2017-03-01

    The environmental degradation of intermediate heat exchanger (IHX) materials in impure helium has been identified as an area with major ramifications on the design of very high-temperature reactors (VHTR). It has been reported that in some helium environments, non-ductile failure is a significant failure mode for Alloy 617 with long-term elevated-temperature service. Non-ductile failure of intermediate exchangers can result in catastrophic consequences; unfortunately, the knowledge of creep crack initiation and creep crack growth (CCG) in candidate alloys is limited. Current codes and code cases for the candidate alloys do not provide specific guidelines for effects of impure helium on the high-temperature behavior. The work reported here explores creep crack growth characterization of Alloy 617 and Alloy 800H at elevated temperatures in air and in impure helium environments, providing information on the reliability of these alloys in VHTR for long-term service. Alloy 617 was found to exhibit superior CCG resistance compared to Alloy 800H. For Alloy 617 tested at 973 K (700 °C), a notable increase in the resistance to crack growth was measured in air compared to that measured in the helium environment; CCG results for Alloy 800H suggest that air and helium environments produce similar behavior. Testing of grain boundary-engineered (GBE) Alloy 617 samples revealed that, although the technique produces superior mechanical properties in many respects, the GBE samples exhibited inferior resistance to creep crack growth compared to the other Alloy 617 samples tested under similar conditions. Grain size is noted as a confounding factor in creep crack growth resistance.

  8. Risk Factors for High Blood Pressure

    Science.gov (United States)

    ... Share this page from the NHLBI on Twitter. Risk Factors for High Blood Pressure Anyone can develop high blood pressure; however, age, ... Lifestyle Habits Unhealthy lifestyle habits can raise your risk for high blood pressure, and they include: Eating too much sodium or ...

  9. Invited Article: High-pressure techniques for condensed matter physics at low temperature

    Science.gov (United States)

    Feng, Yejun; Jaramillo, R.; Wang, Jiyang; Ren, Yang; Rosenbaum, T. F.

    2010-04-01

    Condensed matter experiments at high pressure accentuate the need for accurate pressure scales over a broad range of temperatures, as well as placing a premium on a homogeneous pressure environment. However, challenges remain in diamond anvil cell technology, including both the quality of various pressure transmitting media and the accuracy of secondary pressure scales at low temperature. We directly calibrate the ruby fluorescence R1 line shift with pressure at T=4.5 K using high-resolution x-ray powder diffraction measurements of the silver lattice constant and its known equation of state up to P=16 GPa. Our results reveal a ruby pressure scale at low temperatures that differs by 6% from the best available ruby scale at room T. We also use ruby fluorescence to characterize the pressure inhomogeneity and anisotropy in two representative and commonly used pressure media, helium and methanol:ethanol 4:1, under the same preparation conditions for pressures up to 20 GPa at T=5 K. Contrary to the accepted wisdom, both media show equal levels of pressure inhomogeneity measured over the same area, with a consistent ΔP /P per unit area of ±1.8%/(104 μm2) from 0 to 20 GPa. The helium medium shows an essentially constant deviatoric stress of 0.021±0.011 GPa up to 16 GPa, while the methanol:ethanol mixture shows a similar level of anisotropy up to 10 GPa, above which the anisotropy increases. The quality of both pressure media is further examined under the more stringent requirements of single crystal x-ray diffraction at cryogenic temperature. For such experiments we conclude that the ratio of sample-to-pressure chamber volume is a critical parameter in maintaining sample quality at high pressure, and may affect the choice of pressure medium.

  10. Invited article: High-pressure techniques for condensed matter physics at low temperature.

    Science.gov (United States)

    Feng, Yejun; Jaramillo, R; Wang, Jiyang; Ren, Yang; Rosenbaum, T F

    2010-04-01

    Condensed matter experiments at high pressure accentuate the need for accurate pressure scales over a broad range of temperatures, as well as placing a premium on a homogeneous pressure environment. However, challenges remain in diamond anvil cell technology, including both the quality of various pressure transmitting media and the accuracy of secondary pressure scales at low temperature. We directly calibrate the ruby fluorescence R1 line shift with pressure at T=4.5 K using high-resolution x-ray powder diffraction measurements of the silver lattice constant and its known equation of state up to P=16 GPa. Our results reveal a ruby pressure scale at low temperatures that differs by 6% from the best available ruby scale at room T. We also use ruby fluorescence to characterize the pressure inhomogeneity and anisotropy in two representative and commonly used pressure media, helium and methanol:ethanol 4:1, under the same preparation conditions for pressures up to 20 GPa at T=5 K. Contrary to the accepted wisdom, both media show equal levels of pressure inhomogeneity measured over the same area, with a consistent DeltaP/P per unit area of +/-1.8 %/(10(4) microm(2)) from 0 to 20 GPa. The helium medium shows an essentially constant deviatoric stress of 0.021+/-0.011 GPa up to 16 GPa, while the methanol:ethanol mixture shows a similar level of anisotropy up to 10 GPa, above which the anisotropy increases. The quality of both pressure media is further examined under the more stringent requirements of single crystal x-ray diffraction at cryogenic temperature. For such experiments we conclude that the ratio of sample-to-pressure chamber volume is a critical parameter in maintaining sample quality at high pressure, and may affect the choice of pressure medium.

  11. Invited article : High pressure standards for condensed matter physics at low temperature.

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Y.; Jaramillo, R.; Wang, J.; Ren, Y.; Rosenbaum, T. F.; Univ. of Chicago

    2010-04-01

    Condensed matter experiments at high pressure accentuate the need for accurate pressure scales over a broad range of temperatures, as well as placing a premium on a homogeneous pressure environment. However, challenges remain in diamond anvil cell technology, including both the quality of various pressure transmitting media and the accuracy of secondary pressure scales at low temperature. We directly calibrate the ruby fluorescence R1 line shift with pressure at T = 4.5 K using high-resolution x-ray powder diffraction measurements of the silver lattice constant and its known equation of state up to P = 16 GPa. Our results reveal a ruby pressure scale at low temperatures that differs by 6% from the best available ruby scale at room T. We also use ruby fluorescence to characterize the pressure inhomogeneity and anisotropy in two representative and commonly used pressure media, helium and methanol:ethanol 4:1, under the same preparation conditions for pressures up to 20 GPa at T = 5 K. Contrary to the accepted wisdom, both media show equal levels of pressure inhomogeneity measured over the same area, with a consistent {Delta}P/P per unit area of {+-}1.8?%/(10{sup 4}{mu}m{sup 2}) from 0 to 20 GPa. The helium medium shows an essentially constant deviatoric stress of 0.021{+-}/{+-}0.011 GPa up to 16 GPa, while the methanol:ethanol mixture shows a similar level of anisotropy up to 10 GPa, above which the anisotropy increases. The quality of both pressure media is further examined under the more stringent requirements of single crystal x-ray diffraction at cryogenic temperature. For such experiments we conclude that the ratio of sample-to-pressure chamber volume is a critical parameter in maintaining sample quality at high pressure, and may affect the choice of pressure medium.

  12. Pulsed Helium Ion Beam Induced Deposition: A Means to High Growth Rates

    Energy Technology Data Exchange (ETDEWEB)

    Alkemade, Paul F. A. [Delft University of Technology, Delft, Netherlands; Miro, Hozanna [Delft University of Technology, Delft, Netherlands; Van Veldhoven, Emile [TNO Van Leeuwenhoek Laboratory; Maas, Diederick [TNO Van Leeuwenhoek Laboratory; Smith, Daryl [University of Tennessee, Knoxville (UTK); Rack, P. D. [University of Tennessee, Knoxville (UTK)

    2011-01-01

    The sub-nanometer beam of a helium ion microscope was used to study and optimize helium-ion beam induced deposition of PtC nanopillars with the (CH{sub 3}){sub 3}Pt(CPCH{sub 3}) precursor. The beam current, beam dwell time, precursor refresh time, and beam focus have been independently varied. Continuous beam exposure resulted in narrow but short pillars, while pulsed exposure resulted in thinner and higher ones. Furthermore, at short dwell times the deposition efficiency was very high, especially for a defocused beam. Efficiencies were measured up to 20 times the value for continuous exposure conditions. The interpretation of the experimental data was aided by a Monte Carlo simulation of the deposition. The results indicate that two regimes are operational in ion beam induced deposition (IBID). In the first one, the adsorbed precursor molecules originally present in the beam interaction region decompose. After the original precursor layer is consumed, further depletion is averted and growth continues by the supply of molecules via adsorption and surface diffusion. Depletion around the beam impact site can be distinguished from depletion on the flanges of the growing pillars. The Monte Carlo simulations for low precursor surface coverage reproduce measured growth rates, but predict considerably narrower pillars, especially at short dwell times. Both the experiments and the simulations show that the pillar width rapidly increases with increasing beam diameter. Optimal writing strategy, good beam focusing, and rapid beam positioning are needed for efficient and precise fabrication of extended and complex nanostructures by He-IBID.

  13. High-Pressure Lightweight Thrusters

    Science.gov (United States)

    Holmes, Richard; McKechnie, Timothy; Shchetkovskiy, Anatoliy; Smirnov, Alexander

    2013-01-01

    Returning samples of Martian soil and rock to Earth is of great interest to scientists. There were numerous studies to evaluate Mars Sample Return (MSR) mission architectures, technology needs, development plans, and requirements. The largest propulsion risk element of the MSR mission is the Mars Ascent Vehicle (MAV). Along with the baseline solid-propellant vehicle, liquid propellants have been considered. Similar requirements apply to other lander ascent engines and reaction control systems. The performance of current state-ofthe- art liquid propellant engines can be significantly improved by increasing both combustion temperature and pressure. Pump-fed propulsion is suggested for a single-stage bipropellant MAV. Achieving a 90-percent stage propellant fraction is thought to be possible on a 100-kg scale, including sufficient thrust for lifting off Mars. To increase the performance of storable bipropellant rocket engines, a high-pressure, lightweight combustion chamber was designed. Iridium liner electrodeposition was investigated on complex-shaped thrust chamber mandrels. Dense, uniform iridium liners were produced on chamber and cylindrical mandrels. Carbon/carbon composite (C/C) structures were braided over iridium-lined mandrels and densified by chemical vapor infiltration. Niobium deposition was evaluated for forming a metallic attachment flange on the carbon/ carbon structure. The new thrust chamber was designed to exceed state-of-the-art performance, and was manufactured with an 83-percent weight savings. High-performance C/Cs possess a unique set of properties that make them desirable materials for high-temperature structures used in rocket propulsion components, hypersonic vehicles, and aircraft brakes. In particular, more attention is focused on 3D braided C/Cs due to their mesh-work structure. Research on the properties of C/Cs has shown that the strength of composites is strongly affected by the fiber-matrix interfacial bonding, and that weakening

  14. A compact bellows-driven diamond anvil cell for high-pressure, low-temperature magnetic measurements

    Science.gov (United States)

    Feng, Yejun; Silevitch, D. M.; Rosenbaum, T. F.

    2014-03-01

    We present the design of an efficient bellows-controlled diamond anvil cell that is optimized for use inside the bores of high-field superconducting magnets in helium-3 cryostats, dilution refrigerators, and commercial physical property measurement systems. Design of this non-magnetic pressure cell focuses on in situ pressure tuning and measurement by means of a helium-filled bellows actuator and fiber-coupled ruby fluorescence spectroscopy, respectively. We demonstrate the utility of this pressure cell with ac susceptibility measurements of superconducting, ferromagnetic, and antiferromagnetic phase transitions to pressures exceeding 8 GPa. This cell provides an opportunity to probe charge and magnetic order continuously and with high resolution in the three-dimensional Magnetic Field-Pressure-Temperature parameter space.

  15. Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

    Energy Technology Data Exchange (ETDEWEB)

    Sohrabi, M.; Habibi, M., E-mail: mortezahabibi@gmail.com; Ramezani, V. [Amirkabir University of Technology, Energy Engineering and Physics Department (Iran, Islamic Republic of)

    2017-02-15

    The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of ~4.4 × 10{sup 4} tracks/cm{sup 2} was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due to the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.

  16. How Is High Blood Pressure Treated?

    Science.gov (United States)

    ... or focusing on something calm or peaceful Performing yoga or tai chi Meditating Medicines Blood pressure medicines work in different ways to stop or slow some of the body’s functions that cause high blood pressure. Medicines to lower ...

  17. High blood pressure in women.

    Science.gov (United States)

    Calhoun, D A; Oparil, S

    1997-01-01

    There is a sexual dimorphism in blood pressure of humans and experimental animals: males tend to have higher blood pressure than females with functional ovaries, while ovariectomy or menopause tends to abolish the sexual dimorphism and cause females to develop a "male" pattern of blood pressure. Hypertensive male laboratory animals tend to have NaCl-sensitive blood pressure, while females are NaCl resistant unless their ovaries are removed, in which case NaCl sensitivity appears. The hormonal basis of NaCl sensitivity of blood pressure and of the sexual dimorphism of hypertension remains to be defined. Synthetic estrogens and progestins, as found in oral contraceptives, tend to elevate blood pressure, while naturally occurring estrogens lower it, or have no effect. Hypertension increases cardiovascular risk in women, as well as men, although the benefits of antihypertensive treatment have been more difficult to demonstrate in women. In the population of the United States, women are more aware of their hypertension, more likely to be treated medically, and more likely to have their blood pressure controlled.

  18. HIGH BLOOD PRESSURE: DOES THIS CONCERN ME?

    CERN Multimedia

    2007-01-01

    To find out, the Medical Service's nurses are organising A HIGH BLOOD PRESSURE SCREENING AND PREVENTION CAMPAIGN from Monday, 26th to Thursday, 29th March 2007 at the Infirmary - Building 57 - ground floor A blood pressure test, advice, information and, if necessary, referral for specialist medical treatment will be offered to any person working on the CERN site. High blood pressure is a stealth threat to health. So come and get your blood pressure checked.

  19. HIGH BLOOD PRESSURE: DOES THIS CONCERN ME?

    CERN Multimedia

    2007-01-01

    To find out, the Medical Service's nurses are organising A HIGH BLOOD PRESSURE SCREENING AND PREVENTION CAMPAIGN from Monday, 26th to Thursday, 29th March 2007 at the Infirmary - Building 57 - ground floor A blood pressure test, advice, information and, if necessary, referral for specialist medical treatment will be offered to any person working on the CERN site. High blood pressure is a silent threat to health. So come and get your blood pressure checked.

  20. Evaluation of US demo helium-cooled blanket options

    Energy Technology Data Exchange (ETDEWEB)

    Wong, C.P.C.; McQuillan, B.W.; Schleicher, R.W. [and others

    1995-10-01

    A He-V-Li blanket design was developed as a candidate for the U.S. fusion demonstration power plant. This paper presents an 18 MPa helium-cooled, lithium breeder, V-alloy design that can be coupled to the Brayton cycle with a gross efficiency of 46%. The critical issue of designing to high gas pressure and the compatibility between helium impurities and V-alloy are addressed.

  1. The effects of proton irradiation on the microstructural and mechanical property evolution of inconel X-750 with high concentrations of helium

    Science.gov (United States)

    Judge, C. D.; Bhakhri, V.; Jiao, Z.; Klassen, R. J.; Was, G.; Botton, G. A.; Griffiths, M.

    2017-08-01

    Ni-based alloys, which are used in nuclear applications with a high thermal flux, are shown to contain a high density of helium bubbles within the matrix and aligned along grain boundaries, resulting in lost strength and ductility. In the current investigation, material with and without helium is irradiated with protons up to approximately 60 dpa and 18 000 appm helium. With the use of advanced microscopy and nano-indentation, the microstructural evolution and mechanical hardening has been characterized. The addition of helium decreases the rate of disordering of the gamma prime phase, and suppresses void swelling by forming a region with a high density of helium bubbles, and thereby inhibiting the mobility of freely-migrating point defects. Mechanical hardening from proton-irradiation is consistent with neutron-irradiated Inconel X-750 and Alloy 718.

  2. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs ... track blood pressure readings over a period of time, the health care provider may ask you to ...

  3. Liquid helium

    CERN Document Server

    Atkins, K R

    1959-01-01

    Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.

  4. Ion temperature anisotropy in high power helium neutral beam fuelling experiments in JET

    Energy Technology Data Exchange (ETDEWEB)

    Maas, A.C.; Core, W.G.F.; Gerstel, U.C.; Von Hellermann, M.G.; Koenig, R.W.T.; Marcus, F.B. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    During helium beam fuelling experiments in JET, distinctive anisotropic features have been observed in the velocity distribution function describing both fast and thermal alpha particle populations. During the initial fuelling phase the central helium ion temperature observed perpendicular to the magnetic field is higher than the central electron temperature, while the central helium ion temperature observed parallel to the magnetic field is lower than or equal to the central electron temperature. In order to verify temperature measurements of both perpendicular and parallel lines of sight, other independent methods of deducing the ion temperature are investigated: deuterium ion temperature, deuterium density, comparison with neutron rates and profiles (influence of a possible metastable population of helium). 6 refs., 7 figs.

  5. Statistical mechanics of light elements at high pressure. VII - A perturbative free energy for arbitrary mixtures of H and He

    Science.gov (United States)

    Hubbard, W. B.; Dewitt, H. E.

    1985-01-01

    A model free energy is presented which accurately represents results from 45 high-precision Monte Carlo calculations of the thermodynamics of hydrogen-helium mixtures at pressures of astrophysical and planetophysical interest. The free energy is calculated using free-electron perturbation theory (dielectric function theory), and is an extension of the expression given in an earlier paper in this series. However, it fits the Monte Carlo results more accurately, and is valid for the full range of compositions from pure hydrogen to pure helium. Using the new free energy, the phase diagram of mixtures of liquid metallic hydrogen and helium is calculated and compared with earlier results. Sample results for mixing volumes are also presented, and the new free energy expression is used to compute a theoretical Jovian adiabat and compare the adiabat with results from three-dimensional Thomas-Fermi-Dirac theory. The present theory gives slightly higher densities at pressures of about 10 megabars.

  6. Generation of reactive oxygen and nitrogen species and its effects on DNA damage in lung cancer cells exposed to atmospheric pressure helium/oxygen plasma jets

    Science.gov (United States)

    Chung, Tae Hun; Joh, Hea Min; Kim, Sun Ja; Choi, Ji Ye; Kang, Tae-Hong

    2016-09-01

    We investigated the effects of the operating parameters on the generation of reactive oxygen and nitrogen species (RONS) in the gas and liquid phases exposed to atmospheric pressure a pulsed-dc helium plasma jets. The densities of reactive species including OH radicals were obtained at the plasma-liquid surface and inside the plasma-treated liquids using ultraviolet absorption spectroscopy and chemical probe method. And the nitrite concentration was detected by Griess assay. The data are very suggestive that there is a strong correlation among the production of RONS in the plasmas and liquids. Exposure of plasma to cancer cells increases the cellular levels of RONS, which has been linked to apoptosis and the damage of cellular proteins, and may also indirectly cause structural damage to DNA. To identify the correlation between the production of RONS in cells and plasmas, various assay analyses were performed on plasma treated human lung cancer cells (A549) cells. In addition, the effect of additive oxygen gas on the plasma-induced oxidative stress in cancer cells was investigated. It was observed that DNA damage was significantly increased with helium/oxygen plasma compared to with pure helium plasma.

  7. Application of High Pressure in Food Processing

    OpenAIRE

    Herceg, Z; Režek Jambrak, A; Lelas, V.; Krešić, G.

    2011-01-01

    In high pressure processing, foods are subjected to pressures generally in the range of 100 – 800 (1200) MPa. The processing temperature during pressure treatments can be adjusted from below 0 °C to above 100 °C, with exposure times ranging from a few seconds to 20 minutes and even longer, depending on process conditions. The effects of high pressure are system volume reduction and acceleration of reactions that lead to volume reduction. The main areas of interest regarding high-pressure proc...

  8. Photoionization study of doubly-excited helium at ultra-high resolution

    Energy Technology Data Exchange (ETDEWEB)

    Kaindl, G.; Schulz, K.; Domke, M. [Freie Universitaet Berlin (Germany)] [and others

    1997-04-01

    Ever since the pioneering work of Madden & Codling and Cooper, Fano & Prats on doubly-excited helium in the early sixties, this system may be considered as prototypical for the study of electron-electron correlations. More detailed insight into these states could be reached only much later, when improved theoretical calculations of the optically-excited {sup 1}P{sup 0} double-excitation states became available and sufficiently high energy resolution ({delta}E=4.0 meV) was achieved. This allowed a systematic investigation of the double-excitation resonances of He up to excitation energies close to the double-ionization threshold, I{sub infinity}=79.003 eV, which stimulated renewed theoretical interest into these correlated electron states. The authors report here on striking progress in energy resolution in this grazing-incidence photon-energy range of grating monochromators and its application to hitherto unobservable states of doubly-excited He. By monitoring an extremely narrow double-excitation resonance of He, with a theoretical lifetime width of less than or equal to 5 {mu}eV, a resolution of {delta}E=1.0 meV (FWHM) at 64.1 eV could be achieved. This ultra-high spectral resolution, combined with high photon flux, allowed the investigation of new Rydberg resonances below the N=3 ionization threshold, I{sub 3}, as well as a detailed comparison with ab-initio calculations.

  9. State of the Art Report for a Bearing for VHTR Helium Circulator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Seon; Song, Kee Nam; Kim, Yong Wan; Lee, Won Jae

    2008-10-15

    A helium circulator in a VHTR(Very High Temperature gas-cooled Reactor) plays a core role which translates thermal energy at high temperature from a nuclear core to a steam generator. Helium as a operating coolant circulates a primary circuit in high temperature and high pressure state, and controls thermal output of a nuclear core by controlling flow rate. A helium circulator is the only rotating machinery in a VHTR, and its reliability should be guaranteed for reliable operation of a reactor and stable production of hydrogen. Generally a main helium circulator is installed on the top of a steam generator vessel, and helium is circulated only by a main helium circulator in a normal operation state. An auxiliary or shutdown circulator is installed at the bottom of a reactor vessel, and it is an auxiliary circulator for shutting down a reactor in case of refueling or accelerating cooling down in case of fast cooling. Since a rotating shaft of a helium circulator is supported by bearings, bearings are the important machine elements which determines reliability of a helium circulator and a nuclear reactor. Various types of support bearings have been developed and applied for circulator bearings since 1960s, and it is still developing for developing VHTRs. So it is necessary to review and analyze the current technical state of helium circulator support bearings to develop bearings for Koran developing VHTR helium circulator.

  10. Confined helium on Lagrange meshes

    CERN Document Server

    Baye, Daniel

    2015-01-01

    The Lagrange-mesh method has the simplicity of a calculation on a mesh and can have the accuracy of a variational method. It is applied to the study of a confined helium atom. Two types of confinement are considered. Soft confinements by potentials are studied in perimetric coordinates. Hard confinement in impenetrable spherical cavities is studied in a system of rescaled perimetric coordinates varying in [0,1] intervals. Energies and mean values of the distances between electrons and between an electron and the helium nucleus are calculated. A high accuracy of 11 to 15 significant figures is obtained with small computing times. Pressures acting on the confined atom are also computed. For sphere radii smaller than 1, their relative accuracies are better than $10^{-10}$. For larger radii up to 10, they progressively decrease to $10^{-3}$, still improving the best literature results.

  11. Literature survey of heat transfer and hydraulic resistance of water, carbon dioxide, helium and other fluids at supercritical and near-critical pressures

    Energy Technology Data Exchange (ETDEWEB)

    Pioro, I.L.; Duffey, R.B

    2003-04-01

    This survey consists of 430 references, including 269 Russian publications and 161 Western publications devoted to the problems of heat transfer and hydraulic resistance of a fluid at near-critical and supercritical pressures. The objective of the literature survey is to compile and summarize findings in the area of heat transfer and hydraulic resistance at supercritical pressures for various fluids for the last fifty years published in the open Russian and Western literature. The analysis of the publications showed that the majority of the papers were devoted to the heat transfer of fluids at near-critical and supercritical pressures flowing inside a circular tube. Three major working fluids are involved: water, carbon dioxide, and helium. The main objective of these studies was the development and design of supercritical steam generators for power stations (utilizing water as a working fluid) in the 1950s, 1960s, and 1970s. Carbon dioxide was usually used as the modeling fluid due to lower values of the critical parameters. Helium, and sometimes carbon dioxide, were considered as possible working fluids in some special designs of nuclear reactors. (author)

  12. Surface studies and implanted helium measurements following NOVA high-yield DT experiments

    Energy Technology Data Exchange (ETDEWEB)

    Stoyer, M.A.; Hudson, G.B.

    1997-02-18

    This paper presents the results of three March 6, 1996 direct-drive high-yield DT NOVA experiments and provides `proof-of-principal` results for the quantitative measurement of energetic He ions. Semiconductor quality Si wafers and an amorphous carbon wafer were exposed to NOVA high-yield implosions. Surface damage was sub-micron in general, although the surface ablation was slightly greater for the carbon wafer than for the Si wafers. Melting of a thin ({approx} 0.1{mu}) layer of Si was evident from microscopic investigation. Electron microscopy indicated melted blobs of many different metals (e.g. Al, Au, Ta, Fe alloys, Cu and even Cd) on the surfaces. The yield measured by determining the numbers of atoms of implanted {sup 4}He and {sup 3}He indicate the number of DT fusions to be 9.1({plus_minus}2.3) X 10{sup 12} and DD fusions to be 4.8({plus_minus}1.0) x 10{sup 10}, respectively. The helium DT fusion yield is slightly lower than that of the Cu activation measurement, which was 1.3({plus_minus}0.l) x 10{sup 13} DT fusions.

  13. Metallicity of boron carbides at high pressure

    Science.gov (United States)

    Dekura, Haruhiko; Shirai, Koun; Yanase, Akira

    2010-03-01

    Electronic structure of semiconducting boron carbide at high pressure has been theoretically investigated, because of interests in the positive pressure dependence of resistivity, in the gap closure, and in the phase transition. The most simplest form B12(CCC) is assumed. Under assumptions of hydrostatic pressure and neglecting finite-temperature effects, boron carbide is quite stable at high pressure. The crystal of boron carbide is stable at least until a pressure higher than previous experiments showed. The gap closure occurs only after p=600 GPa on the assumption of the original crystal symmetry. In the low pressure regime, the pressure dependence of the energy gap almost diminishes, which is an exceptional case for semiconductors, which could be one of reasons for the positive pressure dependence of resistivity. A monotonous increase in the apex angle of rhombohedron suggests that the covalent bond continues to increase. The C chain inserted in the main diagonal of rhombohedral structure is the chief reason of this stability.

  14. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Technology Transfer Clinical Trials What Are Clinical Trials? Children & Clinical Studies NHLBI Trials Clinical Trial Websites News & ... are consistently higher than 120/80 mmHg. Your child’s blood pressure numbers are outside average numbers for ...

  15. Diagnosis of High Blood Pressure

    Medline Plus

    Full Text Available ... Related Topics Atherosclerosis DASH Eating Plan Overweight and Obesity Smoking and Your Heart Stroke Send a link ... are consistently higher than 120/80 mmHg. Your child’s blood pressure numbers are outside average numbers for ...

  16. “一拖三”氦压缩机低成本控制实现%Low-cost Control Solution for High Output Helium Compressor

    Institute of Scientific and Technical Information of China (English)

    冯欣宇; 黄阿娟; 武义锋

    2014-01-01

    利用电路印刷板用小型继电器及增强型51单片机,实现对大气量氦压缩机的低成本控制,使其同时可以为3台G-M制冷机提供高压氦气。控制器采集压缩机运行相关参数,具备必要的保护措施,并实现远程控制。在完成控制功能的同时,使整个控制系统的体积和成本得到有效控制。%This paper aims at achieving low-cost control solution for high output helium compressor based on PCB relay and enhanced 51-core microcontroller .Single compressor could provide high-pressure helium for three G-M refrigerators simultaneously .Operating parameters can be obtained by controller ,while remote control interface is designed for users .Necessary protections are considered . The size of entire control system and system cost has been reduced .

  17. Cryogenic spray vaporization in high-velocity helium, argon and nitrogen gasflows

    Science.gov (United States)

    Ingebo, Robert D.

    1993-01-01

    Effects of gas properties on cryogenic liquid-jet atomization in high-velocity helium, nitrogen, and argon gas flows were investigated. Volume median diameter, D(sub v.5e), data were obtained with a scattered-light scanning instrument. By calculating the change in spray drop size, -Delta D(sub v.5)(exp 2), due to droplet vaporization, it was possible to calculate D(sub v.5C). D(sub v.5C) is the unvaporized characteristic drop size formed at the fuel-nozzle orifice. This drop size was normalized with respect to liquid-jet diameter, D(sub O). It was then correlated with several dimensionless groups to give an expression for the volume median diameter of cryogenic LN2 sprays. This expression correlates drop size D(sub v.5c) with aerodynamic and liquid-surface forces so that it can be readily determined in the design of multiphase-flow propellant injectors for rocket combustors.

  18. Helium effects on mechanical properties and microstructure of high fluence ion-irradiated RAFM steel

    Science.gov (United States)

    Ogiwara, H.; Kohyama, A.; Tanigawa, H.; Sakasegawa, H.

    2007-08-01

    Reduced-activation ferritic/martensitic steels, RAFS, are leading candidates for the blanket and first wall of fusion reactors, and effects of displacement damage and helium production on mechanical properties and microstructures are important to these applications. Because it is the most effective way to obtain systematic and accurate information about microstructural response under fusion environment, single-(Fe 3+) and dual-(Fe 3+ + He +) irradiations were performed followed by TEM observation and nano-indentation hardness measurement. Dual-ion irradiation at 420 °C induced finer defect clusters compared to single-ion irradiation. These fine defect clusters caused large differences in the hardness increase between these irradiations. TEM analysis clarified that radiation induced precipitates were MX precipitates (M: Ta, W). Small defects invisible to TEM possibly caused the large increase in hardness, in addition to the hardness increment produced by radiation induced MX. In this work, radiation hardening and microstructural evolution accompanied by the synergistic effects to high fluences are discussed.

  19. Helium cryogenics

    CERN Document Server

    Van Sciver, Steven W

    2012-01-01

    Twenty five years have elapsed since the original publication of Helium Cryogenics. During this time, a considerable amount of research and development involving helium fluids has been carried out culminating in several large-scale projects. Furthermore, the field has matured through these efforts so that there is now a broad engineering base to assist the development of future projects. Helium Cryogenics, 2nd edition brings these advances in helium cryogenics together in an updated form. As in the original edition, the author's approach is to survey the field of cryogenics with emphasis on helium fluids. This approach is more specialized and fundamental than that contained in other cryogenics books, which treat the associated range of cryogenic fluids. As a result, the level of treatment is more advanced and assumes a certain knowledge of fundamental engineering and physics principles, including some quantum mechanics. The goal throughout the work is to bridge the gap between the physics and engineering aspe...

  20. The muonic helium lamb shift experiment

    Energy Technology Data Exchange (ETDEWEB)

    Goetzfried, Johannes; Krauth, Julian [Max-Planck-Institute of Quantum Optics, Garching (Germany); Collaboration: CREMA collaboration

    2014-07-01

    Because of its high sensitivity on finite size effects of the nucleus, the measurement of the Lamb shift in exotic atoms has been on the wish-list of atomic and nuclear physics for a long time. Our previous experiment allowed to determine the proton radius with an order of magnitude higher precision compared to spectroscopic measurements of ordinary hydrogen. The successor experiment in muonic helium is currently performed at the Paul-Scherrer-Institute in Switzerland. Using a low energy muon beam line muons are stopped within low pressure helium gas, where exotic atoms are created. Here we measure the 2S-2P transition frequency of muonic helium illuminated by a pulsed TiSa-laser system pumped with a newly developed Yb-YAG thin disk laser. This measurement will ultimately improve the values of the charge radii of {sup 3}He{sup +} and {sup 4}He{sup +} by an order of magnitude.

  1. High pressure processing for food safety.

    Science.gov (United States)

    Fonberg-Broczek, Monika; Windyga, B; Szczawiński, J; Szczawińska, M; Pietrzak, D; Prestamo, G

    2005-01-01

    Food preservation using high pressure is a promising technique in food industry as it offers numerous opportunities for developing new foods with extended shelf-life, high nutritional value and excellent organoleptic characteristics. High pressure is an alternative to thermal processing. The resistance of microorganisms to pressure varies considerably depending on the pressure range applied, temperature and treatment duration, and type of microorganism. Generally, Gram-positive bacteria are more resistant to pressure than Gram-negative bacteria, moulds and yeasts; the most resistant are bacterial spores. The nature of the food is also important, as it may contain substances which protect the microorganism from high pressure. This article presents results of our studies involving the effect of high pressure on survival of some pathogenic bacteria -- Listeria monocytogenes, Aeromonas hydrophila and Enterococcus hirae -- in artificially contaminated cooked ham, ripening hard cheese and fruit juices. The results indicate that in samples of investigated foods the number of these microorganisms decreased proportionally to the pressure used and the duration of treatment, and the effect of these two factors was statistically significant (level of probability, P high pressure treatment than L. monocytogenes and A. hydrophila. Mathematical methods were applied, for accurate prediction of the effects of high pressure on microorganisms. The usefulness of high pressure treatment for inactivation of microorganisms and shelf-life extention of meat products was also evaluated. The results obtained show that high pressure treatment extends the shelf-life of cooked pork ham and raw smoked pork loin up to 8 weeks, ensuring good micro-biological and sensory quality of the products.

  2. CHRONOBIOLOGY OF HIGH BLOOD PRESSURE

    Science.gov (United States)

    Cornélissen, G.; Halberg, F.; Bakken, E. E.; Wang, Z.; Tarquini, R.; Perfetto, F.; Laffi, G.; Maggioni, C.; Kumagai, Y.; Homolka, P.; Havelková, A.; Dušek, J.; Svačinová, H.; Siegelová, J.; Fišer, B.

    2008-01-01

    BIOCOS, the project aimed at studying BIOlogical systems in their COSmos, has obtained a great deal of expertise in the fields of blood pressure (BP) and heart rate (HR) monitoring and of marker rhythmometry for the purposes of screening, diagnosis, treatment, and prognosis. Prolonging the monitoring reduces the uncertainty in the estimation of circadian parameters; the current recommendation of BIOCOS requires monitoring for at least 7 days. The BIOCOS approach consists of a parametric and a non-parametric analysis of the data, in which the results from the individual subject are being compared with gender- and age-specified reference values in health. Chronobiological designs can offer important new information regarding the optimization of treatment by timing its administration as a function of circadian and other rhythms. New technological developments are needed to close the loop between the monitoring of blood pressure and the administration of antihypertensive drugs. PMID:19122770

  3. High Temperature and Pressure Alkaline Electrolysis

    DEFF Research Database (Denmark)

    Allebrod, Frank

    and oxygen with a new type of alkaline electrolysis cell at high temperatures and pressures. To perform measurements under high pressure and at elevated temperatures it was necessary to build a measurement system around an autoclave which could stand high temperatures up to 250 °C and pressures up to 200 bar...... as well as extremely caustic environments. Based on a literature study to identify resistant materials for these conditions, Inconel 600 was selected among the metals which are available for autoclave construction. An initial single atmosphere high temperature and pressure measurement setup was build...... comprising this autoclave. A second high temperature and pressure measurement setup was build based on experiences from the first setup in order to perform automatized measurements. The conductivity of aqueous KOH at elevated temperatures and high concentrations was investigated using the van der Pauw method...

  4. Voltage and Pressure Scaling of Streamer Dynamics in a Helium Plasma Jet With N2 CO-Flow (Postprint)

    Science.gov (United States)

    2014-08-14

    increased applied voltage. These observed differences in the 2-D scaling properties of ionization wave sustained cathode directed streamer propagation in...streamer propagation in helium versus air16,17 are responsible for the observed differences in the propagation of ionization wave sustained streamer...increase quadratically with increased applied voltage. These observed differences in the 2-D scaling properties of ionization wave sustained cathode

  5. High-resolution electronic spectroscopy of the BODIPY chromophore in supersonic beam and superfluid helium droplets.

    Science.gov (United States)

    Stromeck-Faderl, Anja; Pentlehner, Dominik; Kensy, Uwe; Dick, Bernhard

    2011-07-11

    We present the fluorescence excitation and dispersed emission spectra of the parent compound of the boron dipyrromethene (BODIPY) dye class measured in a supersonic beam and isolated in superfluid helium nanodroplets. The gas-phase spectrum of the isolated molecules displays many low-frequency transitions that are assigned to a symmetry-breaking mode with a strongly nonharmonic potential, presumably the out-of-plane wagging mode of the BF(2) group. The data are in good agreement with transition energies and Franck-Condon factors calculated for a double minimum potential in the upper electronic state. The corresponding transitions do not appear in the helium droplet. This is explained with the quasi-rigid first layer of helium atoms attached to the dopant molecule by van der Waals forces. The spectral characteristics are those of a cyanine dye rather than that of an aromatic chromophore. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Application of High Pressure in Food Processing

    Directory of Open Access Journals (Sweden)

    Herceg, Z.

    2011-01-01

    Full Text Available In high pressure processing, foods are subjected to pressures generally in the range of 100 – 800 (1200 MPa. The processing temperature during pressure treatments can be adjusted from below 0 °C to above 100 °C, with exposure times ranging from a few seconds to 20 minutes and even longer, depending on process conditions. The effects of high pressure are system volume reduction and acceleration of reactions that lead to volume reduction. The main areas of interest regarding high-pressure processing of food include: inactivation of microorganisms, modification of biopolymers, quality retention (especially in terms of flavour and colour, and changes in product functionality. Food components responsible for the nutritive value and sensory properties of food remain unaffected by high pressure. Based on the theoretical background of high-pressure processing and taking into account its advantages and limitations, this paper aims to show its possible application in food processing. The paper gives an outline of the special equipment used in highpressure processing. Typical high pressure equipment in which pressure can be generated either by direct or indirect compression are presented together with three major types of high pressure food processing: the conventional (batch system, semicontinuous and continuous systems. In addition to looking at this technology’s ability to inactivate microorganisms at room temperature, which makes it the ultimate alternative to thermal treatments, this paper also explores its application in dairy, meat, fruit and vegetable processing. Here presented are the effects of high-pressure treatment in milk and dairy processing on the inactivation of microorganisms and the modification of milk protein, which has a major impact on rennet coagulation and curd formation properties of treated milk. The possible application of this treatment in controlling cheese manufacture, ripening and safety is discussed. The opportunities

  7. On the shear strength of tungsten nano-structures with embedded helium

    Science.gov (United States)

    Smirnov, R. D.; Krasheninnikov, S. I.

    2013-08-01

    Modification of plastic properties of tungsten nano-structures under shear stress load due to embedded helium atoms is studied using molecular dynamics modelling. The modelling demonstrates that the yield strength of tungsten nano-structures reduces significantly with increasing embedded helium concentration. At high helium concentrations (>10 at%), the yield strength decreases to values characteristic to the pressure in helium nano-bubbles, which are formed in tungsten under such conditions and thought to be responsible for the formation of nano-fuzz on tungsten surfaces irradiated with helium plasma. It is also shown that tungsten plastic flow strongly facilitates coagulation of helium clusters to larger bubbles. The temperature dependencies of the yield strength are obtained.

  8. Helium Recovery in the LHC Cryogenic System following Magnet Resistive Transitions

    CERN Document Server

    Chorowski, M; Serio, L; Tavian, L; Wagner, U; Van Weelderen, R

    1998-01-01

    A resistive transition (quench) of the Large Hadron Collider magnets provokes the expulsion of helium from the magnet cryostats to the helium recovery system. A high-volume, vacuum-insulated recovery line connected to several uninsulated medium-pressure gas storage tanks, forms the main constituents of the system. Besides a dedicated hardware configuration, helium recovery also implies specific procedures that should follow a quench, in order to conserve the discharged helium and possibly make use of its refrigeration capability. The amount of energy transferred after a quench from the magnets to the helium leaving the cold mass has been estimated on the basis of experimental data. Based on these data, the helium thermodynamic state in the recovery system is calculated using a lumped parameter approach. The LHC magnet quenches are classified ina parametric way from their cryogenic consequences and procedures that should follow the quench are proposed.

  9. Laser techniques in high-pressure geophysics

    Science.gov (United States)

    Hemley, R. J.; Bell, P. M.; Mao, H. K.

    1987-01-01

    Laser techniques in conjunction with the diamond-anvil cell can be used to study high-pressure properties of materials important to a wide range of problems in earth and planetary science. Spontaneous Raman scattering of crystalline and amorphous solids at high pressure demonstrates that dramatic changes in structure and bonding occur on compression. High-pressure Brillouin scattering is sensitive to the pressure variations of single-crystal elastic moduli and acoustic velocities. Laser heating techniques with the diamond-anvil cell can be used to study phase transitions, including melting, under deep-earth conditions. Finally, laser-induced ruby fluorescence has been essential for the development of techniques for generating the maximum pressures now possible with the diamond-anvil cell, and currently provides a calibrated in situ measure of pressure well above 100 gigapascals.

  10. Laser techniques in high-pressure geophysics

    Science.gov (United States)

    Hemley, R. J.; Bell, P. M.; Mao, H. K.

    1987-01-01

    Laser techniques in conjunction with the diamond-anvil cell can be used to study high-pressure properties of materials important to a wide range of problems in earth and planetary science. Spontaneous Raman scattering of crystalline and amorphous solids at high pressure demonstrates that dramatic changes in structure and bonding occur on compression. High-pressure Brillouin scattering is sensitive to the pressure variations of single-crystal elastic moduli and acoustic velocities. Laser heating techniques with the diamond-anvil cell can be used to study phase transitions, including melting, under deep-earth conditions. Finally, laser-induced ruby fluorescence has been essential for the development of techniques for generating the maximum pressures now possible with the diamond-anvil cell, and currently provides a calibrated in situ measure of pressure well above 100 gigapascals.

  11. Research and development for the high-temperature helium-leak detection system (Joint research). Part 2. Development of temperature sensors using optical fibre for the HTTR

    Energy Technology Data Exchange (ETDEWEB)

    Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Urakami, Masao; Saisyu, Sadanori [Japan Atomic Power Co., Tokyo (Japan)

    2003-03-01

    In the second stage of the research and development for a high-temperature helium-leak detection system, the temperature sensor using optical fibres was studied. The sensor detects the helium leakage by the temperature increase surrounded optical fibre with or without heat insulator. Moreover, the applicability of high temperature equipments as the HTTR system was studied. With the sensor we detected 5.0-20.0 cm{sup 3}/s helium leakages within 60 minutes. Also it was possible to detect earlier when the leakage level is at 20.0 cm {sup 3}/s. (author)

  12. Design optimization of high pressure and high temperature piezoresistive pressure sensor for high sensitivity

    Science.gov (United States)

    Niu, Zhe; Zhao, Yulong; Tian, Bian

    2014-01-01

    This paper describes a design method for optimizing sensitivity of piezoresistive pressure sensor in high-pressure and high-temperature environment. In order to prove the method, a piezoresistive pressure sensor (HPTSS) is designed. With the purpose of increasing sensitivity and to improve the measurement range, the piezoresistive sensor adopts rectangular membrane and thick film structure. The configuration of piezoresistors is arranged according to the characteristic of the rectangular membrane. The structure and configuration of the sensor chip are analyzed theoretically and simulated by the finite element method. This design enables the sensor chip to operate in high pressure condition (such as 150 MPa) with a high sensitivity and accuracy. The silicon on insulator wafer is selected to guarantee the thermo stability of the sensor chip. In order to optimize the fabrication and improve the yield of production, an electric conduction step is devised. Series of experiments demonstrates a favorable linearity of 0.13% and a high accuracy of 0.48%. And the sensitivity of HTPSS is about six times as high as a conventional square-membrane sensor chip in the experiment. Compared with the square-membrane pressure sensor and current production, the strength of HPTTS lies in sensitivity and measurement. The performance of the HPTSS indicates that it could be an ideal candidate for high-pressure and high-temperature sensing in real application.

  13. Design optimization of high pressure and high temperature piezoresistive pressure sensor for high sensitivity.

    Science.gov (United States)

    Niu, Zhe; Zhao, Yulong; Tian, Bian

    2014-01-01

    This paper describes a design method for optimizing sensitivity of piezoresistive pressure sensor in high-pressure and high-temperature environment. In order to prove the method, a piezoresistive pressure sensor (HPTSS) is designed. With the purpose of increasing sensitivity and to improve the measurement range, the piezoresistive sensor adopts rectangular membrane and thick film structure. The configuration of piezoresistors is arranged according to the characteristic of the rectangular membrane. The structure and configuration of the sensor chip are analyzed theoretically and simulated by the finite element method. This design enables the sensor chip to operate in high pressure condition (such as 150 MPa) with a high sensitivity and accuracy. The silicon on insulator wafer is selected to guarantee the thermo stability of the sensor chip. In order to optimize the fabrication and improve the yield of production, an electric conduction step is devised. Series of experiments demonstrates a favorable linearity of 0.13% and a high accuracy of 0.48%. And the sensitivity of HTPSS is about six times as high as a conventional square-membrane sensor chip in the experiment. Compared with the square-membrane pressure sensor and current production, the strength of HPTTS lies in sensitivity and measurement. The performance of the HPTSS indicates that it could be an ideal candidate for high-pressure and high-temperature sensing in real application.

  14. Ultra-high vacuum seals operating under pressure and at 1.8 K

    CERN Document Server

    Brunet, J C

    1996-01-01

    The Large Hadron Collider (LHC) project will be the next major high energy physics facility at CERN. Superconducting magnets operating at a magnetic field of 8.4 Tesla in a superfluid helium bath at 1.8 K are required to guide the high energy beams of protons on their trajectory. As part of the magnet qualification tests, magnetic measurements are made using a special device where demountable seals are required. The seals must be leak tight to vacuum and must be able to resist for short periods to pressure bursts up to 20 bar during resistive transitions (quench). Two types of seals have been qualified. Maximum leak rates were in the range 6.10-10 to 1.10-9 mbar.l.s-1, in the worst conditions (20 bar, superfluid helium at 1.8 K).

  15. Techniques in high pressure neutron scattering

    CERN Document Server

    Klotz, Stefan

    2013-01-01

    Drawing on the author's practical work from the last 20 years, Techniques in High Pressure Neutron Scattering is one of the first books to gather recent methods that allow neutron scattering well beyond 10 GPa. The author shows how neutron scattering has to be adapted to the pressure range and type of measurement.Suitable for both newcomers and experienced high pressure scientists and engineers, the book describes various solutions spanning two to three orders of magnitude in pressure that have emerged in the past three decades. Many engineering concepts are illustrated through examples of rea

  16. High-pressure minerals in shocked meteorites

    Science.gov (United States)

    Tomioka, Naotaka; Miyahara, Masaaki

    2017-09-01

    Heavily shocked meteorites contain various types of high-pressure polymorphs of major minerals (olivine, pyroxene, feldspar, and quartz) and accessory minerals (chromite and Ca phosphate). These high-pressure minerals are micron to submicron sized and occur within and in the vicinity of shock-induced melt veins and melt pockets in chondrites and lunar, howardite-eucrite-diogenite (HED), and Martian meteorites. Their occurrence suggests two types of formation mechanisms (1) solid-state high-pressure transformation of the host-rock minerals into monomineralic polycrystalline aggregates, and (2) crystallization of chondritic or monomineralic melts under high pressure. Based on experimentally determined phase relations, their formation pressures are limited to the pressure range up to 25 GPa. Textural, crystallographic, and chemical characteristics of high-pressure minerals provide clues about the impact events of meteorite parent bodies, including their size and mutual collision velocities and about the mineralogy of deep planetary interiors. The aim of this article is to review and summarize the findings on natural high-pressure minerals in shocked meteorites that have been reported over the past 50 years.

  17. Portable high precision pressure transducer system

    Science.gov (United States)

    Piper, T. C.; Morgan, J. P.; Marchant, N. J.; Bolton, S. M.

    A high precision pressure transducer system for checking the reliability of a second pressure transducer system used to monitor the level of a fluid confined in a holding tank is presented. Since the response of the pressure transducer is temperature sensitive, it is continually housed in a battery powered oven which is configured to provide a temperature stable environment at specified temperature for an extended period of time. Further, a high precision temperature stabilized oscillator and counter are coupled to a single board computer to accurately determine the pressure transducer oscillation frequency and convert it to an applied pressure. All of the components are powered by the batteries which during periods of availability of line power are charged by an on-board battery charger. The pressure readings outputs are transmitted to a line printer and a vacuum fluorescent display.

  18. High Accuracy, Miniature Pressure Sensor for Very High Temperatures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SiWave proposes to develop a compact, low-cost MEMS-based pressure sensor for very high temperatures and low pressures in hypersonic wind tunnels. Most currently...

  19. Compression behavior and structure of dense helium at high temperatures by molecular dynamics simulation

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In this work,the isotherm and energy distribution at T=304 K of dense helium are studied by molecular dynamic (MD) simulations with exp-6 potential r*=2.9673 ? (the position of the well minimum) and ε/kB=10.8 K (ε is the well-depth and kB is the Boltzmann constant) given by Peter et al.,and different values of stiffness parameter α.The optimized value of α=12.7 is deduced that can describe the atomic interactions for dense helium satisfactorily.This optimized α in exp-6 potential is used to conduct MD simulations of two isotherms of dense helium at T=300 K and T=298K.The calculations are in good agreement with the experimental.We further employed this method to investigate the equation-of-state and structure of dense helium at higher temperatures and found that when the density remained 1.6 g/cm3,the second peak of the radial distribution function would disappear in the temperature range from 2000 to 3040 K,demonstrating that a solid-liquid transition or decrystallization had occurred.

  20. Compression behavior and structure of dense helium at high temperatures by molecular dynamics simulation

    Institute of Scientific and Technical Information of China (English)

    蔡灵仓; 陈其峰; 经福谦; 陈栋泉

    2000-01-01

    In this work, the isotherm and energy distribution at 7= 304 K of dense helium are studied by molecular dynamic (MD) simulations with exp-6 potential r* = 2.967 3 ε(the position of the well minimum) and ε/kb = 10.8 K (e is the well-depth and kB is the Boltzmann constant) given by Peter et al., and different values of stiffness parameter a. The optimized value of a = 12.7 is deduced that can de-scribe the atomic interactions for dense helium satisfactorily. This optimized a in exp-6 potential is used to conduct MD simulations of two isotherms of dense helium at T= 300 K and T= 298 K. The calcula-tions are in good agreement with the experimental. We further employed this method to investigate the equation-of-state and structure of dense helium at higher temperatures and found that when the density remained l .6 g/cm3, the second peak of the radial distribution function would disappear in the tempera-ture range from 2 000 to 3 040 K, demonstrating that a solid-liquid transition or decrystallization had o

  1. An electron of helium atom under a high-intensity laser field

    Science.gov (United States)

    Falaye, Babatunde James; Sun, Guo-Hua; Adepoju, Adenike Grace; Liman, Muhammed S.; Oyewumi, K. J.; Dong, Shi-Hai

    2017-02-01

    We scrutinize the behavior of eigenvalues of an electron in a helium (He) atom as it interacts with electric field directed along the z-axis and is exposed to linearly polarized intense laser field radiation. To achieve this, we freeze one electron of the He atom at its ionic ground state and the motion of the second electron in the ion core is treated via a more general case of screened Coulomb potential model. Using the Kramers-Henneberger (KH) unitary transformation, which is the semiclassical counterpart of the Block-Nordsieck transformation in the quantized field formalism, the squared vector potential that appears in the equation of motion is eliminated and the resultant equation is expressed in the KH frame. Within this frame, the resulting potential and the corresponding wave function are expanded in Fourier series and using Ehlotzky’s approximation, we obtain a laser-dressed potential to simulate intense laser field. By fitting the more general case of screened Coulomb potential model into the laser-dressed potential, and then expanding it in Taylor series up to O≤ft({{r}4},α 09\\right) , we obtain the solution (eigenvalues and wave function) of an electron in a He atom under the influence of external electric field and high-intensity laser field, within the framework of perturbation theory formalism. We found that the variation in frequency of laser radiation has no effect on the eigenvalues of a He electron for a particular electric field intensity directed along z-axis. Also, for a very strong external electric field and an infinitesimal screening parameter, the system is strongly bound. This work has potential application in the areas of atomic and molecular processes in external fields including interactions with strong fields and short pulses.

  2. A comprehensive statistical investigation of schlieren image velocimetry (SIV) using high-velocity helium jet

    Science.gov (United States)

    Biswas, Sayan; Qiao, Li

    2017-03-01

    A detailed statistical assessment of seedless velocity measurement using Schlieren Image Velocimetry (SIV) was explored using open source Robust Phase Correlation (RPC) algorithm. A well-known flow field, an axisymmetric turbulent helium jet, was analyzed near and intermediate region (0≤ x/d≤ 20) for two different Reynolds numbers, Re d = 11,000 and Re d = 22,000 using schlieren with horizontal knife-edge, schlieren with vertical knife-edge and shadowgraph technique, and the resulted velocity fields from SIV techniques were compared to traditional Particle Image Velocimetry (PIV) measurements. A novel, inexpensive, easy to setup two-camera SIV technique had been demonstrated to measure high-velocity turbulent jet, with jet exit velocities 304 m/s (Mach = 0.3) and 611 m/s (Mach = 0.6), respectively. Several image restoration and enhancement techniques were tested to improve signal to noise ratio (SNR) in schlieren and shadowgraph images. Processing and post-processing parameters for SIV techniques were examined in detail. A quantitative comparison between self-seeded SIV techniques and traditional PIV had been made using correlation statistics. While the resulted flow field from schlieren with horizontal knife-edge and shadowgraph showed excellent agreement with PIV measurements, schlieren with vertical knife-edge performed poorly. The performance of spatial cross-correlations at different jet locations using SIV techniques and PIV was evaluated. Turbulence quantities like turbulence intensity, mean velocity fields, Reynolds shear stress influenced spatial correlations and correlation plane SNR heavily. Several performance metrics such as primary peak ratio (PPR), peak to correlation energy (PCE), the probability distribution of signal and noise were used to compare capability and potential of different SIV techniques.

  3. Antiprotonic helium

    CERN Multimedia

    Eades, John

    2005-01-01

    An exotic atom in w hich an electron and an antiproton orbit a helium nucleus could reveal if there are any differences between matter and antimatter. The author describes this unusual mirror on the antiworld (5 pages)

  4. Assessing the kinetics of high temperature oxidation of Inconel 617 in a dedicated HTR impure helium facility coupling thermogravimetry and gas phase chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Chapovaloff, J., E-mail: chpvlff@aol.com [AREVA NP, Centre Technique, Département Corrosion-Chimie, 30 Bd de l’industrie, 71200 Le Creusot (France); Ecole Nationale Supérieure des Mines, SMS-EMSE, CNRS: UMR5146, LCG, 158 Cours Fauriel, 42023 Saint Etienne (France); Rouillard, F., E-mail: fabien.rouillard@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d’Etude de la Corrosion Non Aqueuse, 91191 Gif sur Yvette (France); Combrade, P., E-mail: pierre.combrade@orange.fr [AREVA NP, Centre Technique, Département Corrosion-Chimie, 30 Bd de l’industrie, 71200 Le Creusot (France); ACXCOR, 63, chemin de l’Arnica, 42660 Le Bessat (France); Pijolat, M., E-mail: mpijolat@emse.fr [Ecole Nationale Supérieure des Mines, SPIN-EMSE, CNRS: UMR5148, LCG, 158 Cours Fauriel, 42023 Saint Etienne (France); Wolski, K., E-mail: wolski@emse.fr [Ecole Nationale Supérieure des Mines, SMS-EMSE, CNRS: UMR5146, LCG, 158 Cours Fauriel, 42023 Saint Etienne (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •New facility coupling thermogravimetry (TGA) with gas phase chromatography (GPC). •Dedicated for HT oxidation study in VHTR impure helium containing CO, H{sub 2}O and H{sub 2}. •The oxidation kinetics obeys a complete parabolic law due to a mixed kinetic regime. •CO contributes during initial stage of oxidation only for very low H{sub 2}O partial pressure. •Long-term oxidation of Inconel 617 by H{sub 2}O is diffusion controlled with constant kp. -- Abstract: A new facility coupling thermogravimetric analysis (TGA) with gas phase chromatography (GPC) has been developed. This facility is dedicated for studying high temperature oxidation of Inconel 617 in impure helium environment containing H{sub 2}O, H{sub 2} and CO at very low partial pressures (in the Pa range), which is representative of the high temperature reactor (HTR) concept developed within the Generation IV Forum. Simultaneous acquisition of mass gain and gas composition has allowed the influence of carbon monoxide and water vapour on the kinetics of oxidation to be studied. GPC measurements of gas consumption have allowed the plotting of individual mass gain curves for oxidation by H{sub 2}O and CO. During isothermal exposure at 1123 K for 20 h, the oxidation was mainly due to water vapour with a minor contribution of carbon monoxide during the first hours. The contribution of water vapour to the oxidation kinetics was extracted. It was shown to obey a complete parabolic law and to be limited by an interfacial reaction during the first few hours of oxidation and to be controlled by a mixed interfacial and diffusion process, diffusion becoming the rate-determining step for long term oxidation. There was very good agreement between GPC measurements and the experimental TGA results.

  5. Magnetic and Superconducting Materials at High Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

    2015-03-24

    The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

  6. High pressure semiconductor physics I

    CERN Document Server

    Willardson, R K; Paul, William; Suski, Tadeusz

    1998-01-01

    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise indeed that this tra...

  7. High Blood Pressure: Medicines to Help You

    Science.gov (United States)

    ... names are given for the drugs in each group.Find your drug. Then read some basic information about your kind of drug. Types of High Blood Pressure Medicines ACE Inhibitors Beta Blockers Calcium Channel Blockers ...

  8. High Blood Pressure May Hike Dementia Risk

    Science.gov (United States)

    ... fullstory_161398.html High Blood Pressure May Hike Dementia Risk New statement from American Heart Association warns ... in middle age, might open the door to dementia, the American Heart Association warns in a new ...

  9. High-pressure oxidation of ethane

    DEFF Research Database (Denmark)

    Hashemi, Hamid; G. Jacobsen, Jon; Rasmussen, Christian T.

    2017-01-01

    Ethane oxidation at intermediate temperatures and high pressures has been investigated in both a laminar flow reactor and a rapid compression machine (RCM). The flow-reactor measurements at 600–900 K and 20–100 bar showed an onset temperature for oxidation of ethane between 700 and 825 K, depending...... as well as results at elevated pressure from literature. The experimental results and the modeling predictions do not support occurrence of NTC behavior in ethane oxidation. Even at the high-pressure conditions of the present work where the C2H5 + O2 reaction yields ethylperoxyl rather than C2H4 + HO2...

  10. High pressure ceramic heat exchanger

    Science.gov (United States)

    Harkins, Bruce D.; Ward, Michael E.

    1998-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a strengthening reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the strengthening reinforcing member. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  11. High-precision spectroscopy of antiprotonic helium-first results from the AD of CERN

    CERN Document Server

    Widmann, E

    2001-01-01

    New results of the laser and microwave spectroscopy of antiprotonic helium "atomcules" obtained in the first year of operation of the Antiproton Decelerator (AD) facility of CERN are presented. They include the discovery of three new resonant transitions and the determination of the zero-density wavelength of six transitions with an accuracy of 130 ppb in the best case. Auger rates of those states were also determined, and two of them were found to be several orders of magnitude larger than expected from a simple estimate based on the multipolarity Delta l, i.e., the jump in angular momentum required for the antiproton to reach the next lower-lying state of ionized pHe /sup ++/. Furthermore, a first signal of a two-laser microwave triple resonance to measure the hyperfine splitting in antiprotonic helium was observed. (39 refs).

  12. Helium production from 84Kr- and 197Au-emulsion interactions at high energies

    Institute of Scientific and Technical Information of China (English)

    Zhang Dong-Hai; Cheng Jin-Xia; Cheng Bin; Wang Fang; Wang Qi; Zhang Hai-Qing; Xu Rong; Jia Hui-Ming; Li Xue-Qin

    2009-01-01

    The properties of the relativistic helium fragments produced in interactions of 94Kr at 1.8 A GeV and 197Au at 10.7 A GeV in emulsion are investigated. The experimental results are compared with those obtained from various projectiles with emulsion collisions at different energies. It is found that the multiplicity distribution of helium projectile fragments (HPFs) is well described by the Koba-Nielsen-Olesen (KNO) scaling presentation. The second Mueller moment f2 of the HPF multiplicity distribution is independent of the projectile energy for the same projectile, but it is dependent on the projectile mass number. The value of f2 increases with the increase of projectile mass number Ap. The negative value of f2, when Ap 69, refers to that the emission of HPFs is correlated. The non-zero f2 moment in this experiment implies the strong correlation existing between the HPFs.

  13. Elasticity of orthoenstatite at high-pressure

    Science.gov (United States)

    Zhang, D.; Jackson, J. M.; Chen, B.; Zhao, J.; Yan, J.

    2011-12-01

    Orthoenstatite is an abundant yet complex mineral in Earth's upper mantle. Despite its abundance, the properties of orthopyroxene at high pressure remain ambiguous (e.g., Zhang et al. 2011; Jahn 2008; Kung et al. 2004). We explored select properties of a synthetic powdered orthoenstatite (Mg0.8757Fe0.13)2Si2O6 sample by X-ray diffraction (XRD) and nuclear resonance inelastic X-ray scattering (NRIXS) as a function of pressure in a neon pressure medium at 300 K. The XRD measurements were carried out at beamline 12.2.2 of the Advanced Light Source (Berkeley, CA), and the sample was studied up to 34 GPa. NRIXS measurements were carried out at sector 3ID-B of the Advanced Photon Source (Chicago, IL) in the pressure range of 3 to 17 GPa. From the raw NRIXS data, the partial phonon density of states (DOS) was derived (e.g., Sturhahn 2004). The volume (or pressure) dependence of several properties, such as the Lamb-Mössbauer factor, mean force constant, specific heat, vibrational entropy, and vibrational kinetic energy were determined from the DOS. We will discuss our results from these combined studies and the implications for Earth's upper mantle. References Zhang, D., J.M. Jackson, W. Sturhahn, and Y. Xiao (2011): Local structure variations observed in orthoenstatite at high-pressures. American Mineralogist, in press. Jahn, S. (2008) High-pressure phase transitions in MgSiO3 orthoenstatite studied by atomistic computer simulation. American Mineralogist, 93(4), 528-532. Kung, J., Li, B., Uchida, T., Wang, Y., Neuville, D., and Liebermann, R. (2004) In situ measurements of sound velocities and densities across the orthopyroxene high-pressure clinopyroxene transition in MgSiO3 at high pressure. Physics of the Earth and Planetary Interiors, 147(1), 27-44. Sturhahn, W. (2004): Nuclear Resonant Spectroscopy. J. Phys. Condens. Matter, 16, S497-S530.

  14. High pressure optical combustion probe

    Energy Technology Data Exchange (ETDEWEB)

    Woodruff, S.D.; Richards, G.A.

    1995-06-01

    The Department of Energy`s Morgantown Energy Technology Center has developed a combustion probe for monitoring flame presence and heat release. The technology involved is a compact optical detector of the OH radical`s UV fluorescence. The OH Monitor/Probe is designed to determine the flame presence and provide a qualitative signal proportional to the flame intensity. The probe can be adjusted to monitor a specific volume in the combustion zone to track spatial fluctuations in the flame. The probe is capable of nanosecond time response and is usually slowed electronically to fit the flame characteristics. The probe is a sapphire rod in a stainless steel tube which may be inserted into the combustion chamber and pointed at the flame zone. The end of the sapphire rod is retracted into the SS tube to define a narrow optical collection cone. The collection cone may be adjusted to fit the experiment. The fluorescence signal is collected by the sapphire rod and transmitted through a UV transmitting, fused silica, fiber optic to the detector assembly. The detector is a side window photomultiplier (PMT) with a 310 run line filter. A Hamamatsu photomultiplier base combined with a integral high voltage power supply permits this to be a low voltage device. Electronic connections include: a power lead from a modular DC power supply for 15 VDC; a control lead for 0-1 volts to control the high voltage level (and therefore gain); and a lead out for the actual signal. All low voltage connections make this a safe and easy to use device while still delivering the sensitivity required.

  15. High-pressure oxidation of methane

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Gersen, Sander

    2016-01-01

    Methane oxidation at high pressures and intermediate temperatures was investigated in a laminar flow reactor and in a rapid compression machine (RCM). The flow-reactor experiments were conducted at 700–900 K and 100 bar for fuel-air equivalence ratios (Φ) ranging from 0.06 to 19.7, all highly...... diluted in nitrogen. It was found that under the investigated conditions, the onset temperature for methane oxidation ranged from 723 K under reducing conditions to 750 K under stoichiometric and oxidizing conditions. The RCM experiments were carried out at pressures of 15–80 bar and temperatures of 800......–1250 K under stoichiometric and fuel-lean (Φ=0.5) conditions. Ignition delays, in the range of 1–100 ms, decreased monotonically with increasing pressure and temperature. A chemical kinetic model for high-pressure methane oxidation was established, with particular emphasis on the peroxide chemistry...

  16. Structures of Liquid Aluminium under High Pressure

    Institute of Scientific and Technical Information of China (English)

    LI Hui; WANG Guang-Hou; BIAN Xiu-Fang; ZHANG Lin

    2001-01-01

    Molecular dynamics simulation has been carried out for melt A1 under constant temperature and constant pressure. The interaction between atoms is described by tight-binding many-body potentials based on the second moment approximation to the electronic density of states. The pair correlation function and the pair analysis technique are used to reveal the structural features of liquid Al under normal and high pressure. High pressure is favourable to the existence of bcc clusters 1661 and 1441, but has no effect on the fcc cluster 1421. The bond pair 1551 and 1541 with fivefold symmetry exists at high pressure. The microstructure of liquid is more similar to the non-crystalline structure than to the crystalline structure. The simulation results are supported by thex-ray experimental results.

  17. Electron density change of atmospheric-pressure plasmas in helium flow depending on the oxygen/nitrogen ratio of the surrounding atmosphere

    Science.gov (United States)

    Tomita, Kentaro; Urabe, Keiichiro; Shirai, Naoki; Sato, Yuta; Hassaballa, Safwat; Bolouki, Nima; Yoneda, Munehiro; Shimizu, Takahiro; Uchino, Kiichiro

    2016-06-01

    Laser Thomson scattering was applied to an atmospheric-pressure plasma produced in a helium (He) gas flow for measuring the spatial profiles of electron density (n e) and electron temperature (T e). Aside from the He core flow, the shielding gas flow of N2 or synthesized air (\\text{N}2:\\text{O}2 = 4:1) surrounding the He flow was introduced to evaluate the effect of ambient gas components on the plasma parameters, eliminating the effect of ambient humidity. The n e at the discharge center was 2.7 × 1021 m-3 for plasma generated with N2/O2 shielding gas, 50% higher than that generated with N2 shielding.

  18. Design of an R.F. Excited Helium Neon Visible Gas Laser and Study of the Optimal Conditions for Gas Mixtures and Pressures

    Directory of Open Access Journals (Sweden)

    D. P. Juyal

    1972-10-01

    Full Text Available Design of a continuous were helium-neon visible gas laser has been described. Brewster angle window of fused quartz and external concave mirrors of B.S.C. glass have been used in the fabrication of resonant cavity. An RF oscillator having variable frequency in the range of 20-30 MHz and an out-put power of about 50 watts served as excitation source. Different mixture ratios of He and Ne have been tried and for each ratio power output was measured versus total pressure inside the discharge tube keeping cavity length constant. The optimum power output has been obtained for 5:1 mixture at 1.4 torr for a tube of length 55 cm and internal diameter 0.5 cm. Laser action at 1.53 meu has been achieved.`

  19. Effects of the pulse width on the reactive species production and DNA damage in cancer cells exposed to atmospheric pressure microsecond-pulsed helium plasma jets

    Science.gov (United States)

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Kang, Tae Hong; Chung, T. H.

    2017-08-01

    Plasma-liquid and plasma-cell interactions were investigated using an atmospheric pressure dc microsecond-pulsed helium plasma jet. We investigated the effects of the electrical parameters such as applied voltage and pulse width (determined by the pulse frequency and duty ratio) on the production of reactive species in the gas/liquid phases and on the DNA damage responses in the cancer cells. The densities of reactive species including OH radicals were estimated inside the plasma-treated liquids using a chemical probe method, and the nitrite concentration was detected by Griess assay. Importantly, the more concentration of OH resulted in the more DNA base oxidation and breaks in human lung cancer A549 cells. The data are very suggestive that there is strong correlation between the production of OH in the plasmas/liquids and the DNA damage.

  20. Determination of the proton-to-helium ratio in cosmic rays at ultra-high energies from the tail of the Xmax distribution

    Science.gov (United States)

    Yushkov, A.; Risse, M.; Werner, M.; Krieg, J.

    2016-12-01

    We present a method to determine the proton-to-helium ratio in cosmic rays at ultra-high energies. It makes use of the exponential slope, Λ, of the tail of the Xmax distribution measured by an air shower experiment. The method is quite robust with respect to uncertainties from modeling hadronic interactions and to systematic errors on Xmax and energy, and to the possible presence of primary nuclei heavier than helium. Obtaining the proton-to-helium ratio with air shower experiments would be a remarkable achievement. To quantify the applicability of a particular mass-sensitive variable for mass composition analysis despite hadronic uncertainties we introduce as a metric the 'analysis indicator' and find an improved performance of the Λ method compared to other variables currently used in the literature. The fraction of events in the tail of the Xmax distribution can provide additional information on the presence of nuclei heavier than helium in the primary beam.

  1. High pressure Raman scattering of silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Khachadorian, Sevak; Scheel, Harald; Thomsen, Christian [Institut fuer Festkoerperphysik, Technische Universitaet Berlin, 10623 Berlin (Germany); Papagelis, Konstantinos [Materials Science Department, University of Patras, 26504 Patras (Greece); Colli, Alan [Nokia Research Centre, 21 J J Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Ferrari, Andrea C, E-mail: khachadorian@physik.tu-berlin.de [Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom)

    2011-05-13

    We study the high pressure response, up to 8 GPa, of silicon nanowires (SiNWs) with {approx} 15 nm diameter, by Raman spectroscopy. The first order Raman peak shows a superlinear trend, more pronounced compared to bulk Si. Combining transmission electron microscopy and Raman measurements we estimate the SiNWs' bulk modulus and the Grueneisen parameters. We detect an increase of Raman linewidth at {approx} 4 GPa, and assign it to pressure induced activation of a decay process into LO and TA phonons. This pressure is smaller compared to the {approx} 7 GPa reported for bulk Si. We do not observe evidence of phase transitions, such as discontinuities or change in the pressure slopes, in the investigated pressure range.

  2. High-pressure cell for neutron diffraction with in situ pressure control at cryogenic temperatures.

    Science.gov (United States)

    Jacobsen, Matthew K; Ridley, Christopher J; Bocian, Artur; Kirichek, Oleg; Manuel, Pascal; Khalyavin, Dmitry; Azuma, Masaki; Attfield, J Paul; Kamenev, Konstantin V

    2014-04-01

    Pressure generation at cryogenic temperatures presents a problem for a wide array of experimental techniques, particularly neutron studies due to the volume of sample required. We present a novel, compact pressure cell with a large sample volume in which load is generated by a bellow. Using a supply of helium gas up to a pressure of 350 bar, a load of up to 78 kN is generated with leak-free operation. In addition, special fiber ports added to the cryogenic center stick allow for in situ pressure determination using the ruby pressure standard. Mechanical stability was assessed using finite element analysis and the dimensions of the cell have been optimized for use with standard cryogenic equipment. Load testing and on-line experiments using NaCl and BiNiO3 have been done at the WISH instrument of the ISIS pulsed neutron source to verify performance.

  3. High-pressure cell for neutron diffraction with in situ pressure control at cryogenic temperatures

    Science.gov (United States)

    Jacobsen, Matthew K.; Ridley, Christopher J.; Bocian, Artur; Kirichek, Oleg; Manuel, Pascal; Khalyavin, Dmitry; Azuma, Masaki; Attfield, J. Paul; Kamenev, Konstantin V.

    2014-04-01

    Pressure generation at cryogenic temperatures presents a problem for a wide array of experimental techniques, particularly neutron studies due to the volume of sample required. We present a novel, compact pressure cell with a large sample volume in which load is generated by a bellow. Using a supply of helium gas up to a pressure of 350 bar, a load of up to 78 kN is generated with leak-free operation. In addition, special fiber ports added to the cryogenic center stick allow for in situ pressure determination using the ruby pressure standard. Mechanical stability was assessed using finite element analysis and the dimensions of the cell have been optimized for use with standard cryogenic equipment. Load testing and on-line experiments using NaCl and BiNiO3 have been done at the WISH instrument of the ISIS pulsed neutron source to verify performance.

  4. Temporal and spatial profiles of emission intensities in atmospheric pressure helium plasma jet driven by microsecond pulse: Experiment and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ruixue; Zhang, Cheng; Yan, Ping; Shao, Tao, E-mail: st@mail.iee.ac.cn [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Shen, Yuan [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Zhu, Weidong [Department of Applied Science and Technology, Saint Peter' s University, Jersey City, New Jersey 07306 (United States); Babaeva, Natalia Yu.; Naidis, George V. [Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow 125412 (Russian Federation)

    2015-09-28

    A needle-circular electrode structure helium plasma jet driven by microsecond pulsed power is studied. Spatially resolved emission results show that the emission intensity of He(3{sup 3}S{sub 1}) line decreases monotonically along the axial direction, while those of N{sub 2}(C{sup 3}Π{sub u}), N{sub 2}{sup +}(B{sup 2}∑{sup +}{sub u}), and O(3p{sup 5}P) reach their maxima at 3 cm, 2.6 cm, and 1.4 cm, respectively. The plasma plume of the four species shows different characteristics: The N{sub 2} emission plume travels at a fast speed along the entire plasma jet; the N{sub 2}{sup +} emission plume is composed of a bright head and relatively weak tail and travels a shorter distance than the N{sub 2} emission plume; the He emission plume travels at a slower speed for only a very short distance; propagation of the O emission plume is not observed. Results of calculation of radiation fluxes emitted by positive streamers propagating along helium plasma jets are presented. It is shown, in agreement with the results of the present experiment and with other available experimental data, that the intensities of radiation of N{sub 2}(C{sup 3}Π{sub u}) molecules and He(3{sup 3}S{sub 1}) atoms vary with time (along the plasma jet) quite differently. The factors resulting in this difference are discussed.

  5. High-temperature gas-cooled reactor helium compatibility studies: results of 10,000-hour exposure of selected alloys in simulated reactor helium

    Energy Technology Data Exchange (ETDEWEB)

    Lechtenberg, T.A.; Stevenson, R.D.; Johnson, W.R.

    1980-05-01

    Work on the HTGR Helium Compatibility Task accomplished during the period March 31, 1977 through September 30, 1979, is documented in this report. Emphasis is on the results and analyses of creep data to 10,000 h and the detailed metallurgical evaluations performed on candidate alloy specimens tested for up to 10,000 h. Long-term creep and unstressed aging data in controlled-impurity helium and in air at 800, 900, and 1000/sup 0/C are reported for alloys included in the program in FY-76, including the wrought solid-solution-strengthened alloys, Hastelloy X, Hastelloy S, RA 333, and HD 556, and the centrifugally cast austenitic alloys, HK 40, Supertherm, Manaurite 36X, Manaurite 36XS, and Manaurite 900.

  6. High pressure studies of potassium perchlorate

    Science.gov (United States)

    Pravica, Michael; Wang, Yonggang; Sneed, Daniel; Reiser, Sharissa; White, Melanie

    2016-09-01

    Two experiments are reported on KClO4 at extreme conditions. A static high pressure Raman study was first conducted to 18.9 GPa. Evidence for at least two new phases was observed: one between 2.4 and 7.7 GPa (possibly sluggish), and the second near 11.7 GPa. Then, the X-ray induced decomposition rate of potassium perchlorate (KClO4 → hν KCl + 2O2) was studied up to 15.2 GPa. The time-dependent growth of KCl and O2 was monitored. The decomposition rate slowed at higher pressures. We present the first direct evidence for O2 crystallization at higher pressures, demonstrating that O2 molecules aggregate at high pressure.

  7. Operation of a high temperature ion source at the helium-jet on-line isotope separator facility HELIOS

    Energy Technology Data Exchange (ETDEWEB)

    Bruegger, M.; Hildebrand, N.; Karlewski, T.; Trautmann, N. (Mainz Univ. (Germany, F.R.). Inst. fuer Kernchemie); Mazumdar, A.K. (Marburg Univ. (Germany, F.R.). Fachbereich Physik); Herrmann, G. (Mainz Univ. (Germany, F.R.). Inst. fuer Kernchemie; Gesellschaft fuer Schwerionenforschung m.b.H., Darmstadt (Germany, F.R.))

    1985-02-01

    The performance of a high temperature ion source coupled to a helium gas-jet transport system for an efficient mass separation of neutron-rich alkaline earth and lanthanide isotopes is reported and the results of overall efficiency measurements using different cluster materials in the gas-jet are given. A fast, microprocessor controlled tape transport system for ..gamma..-spectroscopic studies on short-lived isotopes is described. Some results on the decay of 3.8sub(-s) /sup 152/Pr are presented.

  8. High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

    Science.gov (United States)

    Okojie, Robert S.; Meredith, Roger D.; Chang, Clarence T.; Savrun, Ender

    2014-01-01

    Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.

  9. High temperature and pressure alkaline electrolysis

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2013-01-01

    the operational temperature and pressure to produce pressurized hydrogen at high rate (m3 H2·h-1·m-2 cell area) and high electrical efficiency. This work describes an exploratory technical study of the possibility to produce hydrogen and oxygen with a new type of alkaline electrolysis cell at high temperatures...... for immobilization of aqueous KOH solutions. Electrolysis cells with this electrolyte and metal foam based gas diffusion electrodes were successfully demonstrated at temperatures up to 250 °C at 40 bar. Different electro-catalysts were tested in order to reduce the oxygen and hydrogen overpotentials. Current...

  10. Maximum Expected Wall Heat Flux and Maximum Pressure After Sudden Loss of Vacuum Insulation on the Stratospheric Observatory for Infrared Astronomy (SOFIA) Liquid Helium (LHe) Dewars

    Science.gov (United States)

    Ungar, Eugene K.

    2014-01-01

    The aircraft-based Stratospheric Observatory for Infrared Astronomy (SOFIA) is a platform for multiple infrared observation experiments. The experiments carry sensors cooled to liquid helium (LHe) temperatures. A question arose regarding the heat input and peak pressure that would result from a sudden loss of the dewar vacuum insulation. Owing to concerns about the adequacy of dewar pressure relief in the event of a sudden loss of the dewar vacuum insulation, the SOFIA Program engaged the NASA Engineering and Safety Center (NESC). This report summarizes and assesses the experiments that have been performed to measure the heat flux into LHe dewars following a sudden vacuum insulation failure, describes the physical limits of heat input to the dewar, and provides an NESC recommendation for the wall heat flux that should be used to assess the sudden loss of vacuum insulation case. This report also assesses the methodology used by the SOFIA Program to predict the maximum pressure that would occur following a loss of vacuum event.

  11. Crystal structures at high pressures and temperatures

    Science.gov (United States)

    Caldwell, Wendel Alexander

    2000-10-01

    The diamond anvil cell (DAC) is a unique instrument that can generate pressures equivalent to those inside planetary interiors (pressures on the order of 1 million atmospheres) under sustained conditions. When combined with a bright source of collimated x-rays, the DAC can be used to probe the structure of materials in-situ at ultra-high pressures. An understanding of the high-pressure structure of materials is important in determining what types of processes may take place in the Earth at great depths. Motivated by previous studies showing that xenon becomes metallic at pressures above ˜1 megabar (100 GPa), we examined the stable structures and reactivity of xenon at pressures approaching that of the core-mantle boundary in the Earth. Our findings indicate the transformation of xenon from face-centered cubic (fcc) to hexagonal close-packed (hcp) structures is kinetically hindered at room temperature, with the equilibrium fcc--hcp phase boundary at 21 (+/-3) gigapascals, a pressure lower than was previously thought. Additionally, we find no tendency on the part of xenon to form a metal alloy with iron or platinum to at least 100 to 150 gigapascals, making it unlikely that the Earth's core serves as a reservoir for primordial xenon. Measurements of the compressibility of natural (Mg.75,Fe .25)2SiO4 gamma-spinel at pressures of the Earth's transition zone yield a pressure derivative of the bulk modulus K0 ' = 6.3 (+/-0.3). As gamma-spinel is considered to be a dominant mineral phase of the transition-zone of the Earth's mantle (400--670 km depth), the relatively high value of K0' for gamma-spinel may help explain the rapid increase with depth of seismic velocities through the transition zone. The thermodynamics, mechanisms and kinetics of pressure-induced amorphization are not well understood. We report here new studies indicating little or no entropy difference between the crystalline and glassy states of Ca(OH) 2 (portlandite). Additional work on the pressure

  12. High pressure, high current, low inductance, high reliability sealed terminals

    Science.gov (United States)

    Hsu, John S [Oak Ridge, TN; McKeever, John W [Oak Ridge, TN

    2010-03-23

    The invention is a terminal assembly having a casing with at least one delivery tapered-cone conductor and at least one return tapered-cone conductor routed there-through. The delivery and return tapered-cone conductors are electrically isolated from each other and positioned in the annuluses of ordered concentric cones at an off-normal angle. The tapered cone conductor service can be AC phase conductors and DC link conductors. The center core has at least one service conduit of gate signal leads, diagnostic signal wires, and refrigerant tubing routed there-through. A seal material is in direct contact with the casing inner surface, the tapered-cone conductors, and the service conduits thereby hermetically filling the interstitial space in the casing interior core and center core. The assembly provides simultaneous high-current, high-pressure, low-inductance, and high-reliability service.

  13. Curved and conformal high-pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Croteau, Paul F.; Kuczek, Andrzej E.; Zhao, Wenping

    2016-10-25

    A high-pressure vessel is provided. The high-pressure vessel may comprise a first chamber defined at least partially by a first wall, and a second chamber defined at least partially by the first wall. The first chamber and the second chamber may form a curved contour of the high-pressure vessel. A modular tank assembly is also provided, and may comprise a first mid tube having a convex geometry. The first mid tube may be defined by a first inner wall, a curved wall extending from the first inner wall, and a second inner wall extending from the curved wall. The first inner wall may be disposed at an angle relative to the second inner wall. The first mid tube may further be defined by a short curved wall opposite the curved wall and extending from the second inner wall to the first inner wall.

  14. Superconductivity from insulating elements under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Katsuya

    2015-07-15

    Highlights: • Even insulating molecule can become metal and superconductor by pressure with relatively high T{sub c}. • The highest T{sub c} is observed in sulfur with 17 K at 160 GPa. • Hydrogen is the best candidate of the highest T{sub c} element. - Abstract: The insulating and superconducting states would seem to have very different characteristics. Can any insulator become a superconductor? One proven method, doping an insulating material with carriers, can create itinerant states inside the gap between the conduction and valence bands. Another method is to squeeze the structure by applying pressure. Pressure can expand the bandwidth and also narrow the energy band gap. So the first step to turn an insulator into a superconductor is to make it metallic. Here we review our experimental research and results on superconductivity induced by applying pressure to insulating molecular systems such as elemental molecules.

  15. Effects of aging in high temperature helium environments on room temperature tensile properties of nickel-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Daejong [Department of Nuclear and Quantum Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Nuclear Materials Technology Development Division, KAERI, 150 Deogjin-dong, Yuseong-gu, Daejeon 305-600 (Korea, Republic of); Sah, Injin [Department of Nuclear and Quantum Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Jang, Changheui, E-mail: chjang@kaist.ac.kr [Department of Nuclear and Quantum Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2011-01-25

    Research highlights: {yields} Haynes 230 is susceptible to carburization, but Alloy 617 to decarburization and inter-granular oxidation. {yields} Decarburization of Nickel-base superalloys can be accelerated in impure helium with H{sub 2}. {yields} Aging heat treatment causes inter-granular fracture primarily along inter-granular oxide and grain boundary carbides, which results in the loss of ductility. {yields} Thin-plate specimen of Alloy 617 tends to favor failure by glide plane fracture when it is heavily decarburized. - Abstract: The influence of high temperature aging treatment on room temperature tensile properties of wrought nickel-base superalloys Alloy 617 and Haynes 230 was investigated. A significant decrease in elongation was observed for Alloy 617 exposed to a heavily oxidizing and decarburizing condition because of coarsening of grain boundary carbides and extensive inter-granular oxidation. On the other hand, Haynes 230 showed much lower ductility when exposed to a heavily carburizing condition, especially at 1000 deg. C because extensive carburization occurred due to a reaction with tungsten. Considerable loss of ductility for Alloy 617 and Haynes 230 was also observed in He-H{sub 2}-H{sub 2}O-CO-CO{sub 2}-CH{sub 4} and He-H{sub 2}O-CO-CO{sub 2} environments, which were the slightly oxidizing and decarburizing conditions. Loss of ductility was predominantly associated with brittle inter-granular cracking, while the extent of loss of ductility decreased depending on the decarburization depth. Decarburization was observed more extensively in helium with H{sub 2}-H{sub 2}O-CO-CO{sub 2}-CH{sub 4} than helium with H{sub 2}O-CO-CO{sub 2}, and for Alloy 617 than for Haynes 230. Finally, the role of H{sub 2} in accelerating decarburization is discussed.

  16. Thermal-hydraulic optimization of flexible transfer lines for liquid helium; Thermohydraulische Optimierung flexibler Transferleitungen fuer Fluessighelium

    Energy Technology Data Exchange (ETDEWEB)

    Dittmar, Nico; Haberstroh, Christoph; Hesse, U. [Technische Univ. Dresden (Germany). Bitzer-Stiftungsprofessur fuer Kaelte-, Kryo- und Kompressorentechnik; Wolfram, M.; Krzyzowski, M.; Raccanelli, A. [CryoVac Gesellschaft fuer Tieftemperaturtechnik mbH und Co. KG, Troisdorf (Germany)

    2014-07-01

    Cooling systems and applications at very low temperatures are based on the use of liquid helium as cryogenic agent; the normal boiling temperature of helium-4 is 4.2 K. Due to the restricted economic production possibilities and the high energetic expenditure for helium liquefaction an efficient and sustainable handling with the resources is recommended. In university facilities the liquid helium is usually stored in containers and filled into smaller containers for transport using cryogenic transfer lines. This procedure can cause 20% loss by evaporation due to heat input and friction pressure losses. The gaseous helium has to be collected for re-liquefaction. The contribution shows that using systematic measurements an increase of the transfer rate and the efficiency of the helium filling system can be reached by a modified transfer line design.

  17. Pressure distribution in a quasi-hydrostatic pressure medium: A finite element analysis

    Science.gov (United States)

    Tempere, Jacques; Silvera, Isaac F.

    2011-12-01

    The highest quality pressures on samples in a diamond anvil cell (DAC) at high pressures are produced using quasi-hydrostatic pressurization media such as helium or hydrogen. In this paper we carry out a finite element analysis of pressure distributions in a DAC using helium and non-hydrostatic argon pressurization media. We find that samples and ruby chips are at substantially higher pressures than the pressurization media, although this is sharply reduced by using helium, which has a low yield strength for the shear modulus. The deviations in pressure of the different samples (and ruby) from the pressurization media differ and depend on their elastic constants. Our observations may account for the distribution of pressures in metallic markers found in a recent calibration of the ruby scale to high pressures.

  18. High pressure water jet cutting and stripping

    Science.gov (United States)

    Hoppe, David T.; Babai, Majid K.

    1991-01-01

    High pressure water cutting techniques have a wide range of applications to the American space effort. Hydroblasting techniques are commonly used during the refurbishment of the reusable solid rocket motors. The process can be controlled to strip a thermal protective ablator without incurring any damage to the painted surface underneath by using a variation of possible parameters. Hydroblasting is a technique which is easily automated. Automation removes personnel from the hostile environment of the high pressure water. Computer controlled robots can perform the same task in a fraction of the time that would be required by manual operation.

  19. High temperature and pressure alkaline electrolysis

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2013-01-01

    and pressures. Two measurement systems were built to perform measurements under high pressures and at elevated temperatures of up to 95 bar and 250 °C, respectively. The conductivity of aqueous KOH and aqueous KOH immobilized in a porous SrTiO3 structure were investigated at elevated temperatures and high...... the operational temperature and pressure to produce pressurized hydrogen at high rate (m3 H2·h-1·m-2 cell area) and high electrical efficiency. This work describes an exploratory technical study of the possibility to produce hydrogen and oxygen with a new type of alkaline electrolysis cell at high temperatures...... concentrations of the electrolyte using the van der Pauw method in combination with electrochemical impedance spectroscopy (EIS). Conductivity values as high as 2.9 S cm-1 for 45 wt% KOH aqueous KOH and 0.84 S cm-1 for the immobilized KOH of the same concentration were measured at 200 °C. Porous SrTiO3 was used...

  20. Two phase coexistence for the hydrogen-helium mixture

    CERN Document Server

    Fantoni, Riccardo

    2015-01-01

    We use our newly constructed quantum Gibbs ensemble Monte Carlo algorithm to perform computer experiments for the two phase coexistence of a hydrogen-helium mixture. Our results are in quantitative agreement with the experimental results of C. M. Sneed, W. B. Streett, R. E. Sonntag, and G. J. Van Wylen. The difference between our results and the experimental ones is in all cases less than 15% relative to the experiment, reducing to less than 5% in the low helium concentration phase. At the gravitational inversion between the vapor and the liquid phase, at low temperatures and high pressures, the quantum effects become relevant. At extremely low temperature and pressure the first component to show superfluidity is the helium in the vapor phase.

  1. Tensile properties of V-Cr-Ti alloys after exposure in helium and low-partial-pressure oxygen environments

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

    1997-04-01

    A test program is in progress to evaluate the effect of oxygen at low pO{sub 2} on the tensile properties of V-(4-5)wt% Cr-(4-5)wt% Ti alloys. Some of the tensile specimens were precharged with oxygen at low pO{sub 2} at 500{degrees}C and reannealed in vacuum at 500{degrees}C in environments with various pO{sub 2} levels and subsequently tensile tested at room temperature. The preliminary results indicate that both approaches are appropriate for evaluating the effect of oxygen uptake on the tensile properties of the alloys. The data showed that in the relatively short-time tests conducted thus far, the maximum engineering stress slightly increased after oxygen exposure but the uniform and total elongation values exhibited significant decrease after exposure in oxygen-containing environments. The data for a specimen exposed to a helium environment were similar to those obtained in low pO{sub 2} environments.

  2. High pressure effects on allergen food proteins.

    Science.gov (United States)

    Somkuti, Judit; Smeller, László

    2013-12-15

    There are several proteins, which can cause allergic reaction if they are inhaled or ingested. Our everyday food can also contain such proteins. Food allergy is an IgE-mediated immune disorder, a growing health problem of great public concern. High pressure is known to affect the structure of proteins; typically few hundred MPa pressure can lead to denaturation. That is why several trials have been performed to alter the structure of the allergen proteins by high pressure, in order to reduce its allergenicity. Studies have been performed both on simple protein solutions and on complex food systems. Here we review those allergens which have been investigated under or after high pressure treatment by methods capable of detecting changes in the secondary and tertiary structure of the proteins. We focus on those allergenic proteins, whose structural changes were investigated by spectroscopic methods under pressure in correlation with the observed allergenicity (IgE binding) changes. According to this criterion we selected the following allergen proteins: Mal d 1 and Mal d 3 (apple), Bos d 5 (milk), Dau c 1 (carrot), Gal d 2 (egg), Ara h 2 and Ara h 6 (peanut), and Gad m 1 (cod).

  3. High pressure effects in anaesthesia and narcosis.

    Science.gov (United States)

    Wlodarczyk, Agnieszka; McMillan, Paul F; Greenfield, Susan A

    2006-10-01

    There is growing interest in determining the effects of high pressure on biological functions. Studies of brain processes under hyperbaric conditions can give a unique insight into phenomena such as nitrogen narcosis, inert gas anaesthesia, and pressure reversal of the effects of anaesthetic and narcotic agents. Such research may shed light on the action of anaesthetics, which remains poorly understood, and on the nature of consciousness itself. Various studies have established the behavioural response of organisms to hyperbaric conditions, in the presence or absence of anaesthetic agents. At the molecular level, X-ray crystallography has been used to investigate the incorporation of species like Xe in hydrophobic pockets within model ion channels that may account for pressure effects on neuronal transmission. New magnetic resonance imaging techniques are providing tomographic three-dimensional images that detail brain structure and function, and that can be correlated with behavioural studies and psychological test results. Such whole organ techniques are linked to the molecular scale via voltage-sensitive dye (VSD) imaging studies on brain slices that provide time-resolved images of the dynamic formation and interconnection of inter-neuronal complexes. The VSD experiments are readily adapted to in situ studies under high pressure conditions. In this tutorial review we review the current state of knowledge of hyperbaric effects on brain processes: anaesthesia and narcosis, recent studies at the molecular level via protein crystallography at high pressure in a Xe atmosphere, and we also present some preliminary results of VSD imaging of brain slices under hyperbaric conditions.

  4. Introduction to High-Pressure Science

    Science.gov (United States)

    Dera, Przemyslaw

    To a common person pressure is just one of the parameters that describe a thermodynamic state. We all hear about it in everyday weather forecasts, and most of us do not associate it with anything particularly unique. Probably the most intuitive idea of the effect of high-pressure comes from movies, where submarine sinking to the bottom of the ocean is gradually crushed by the surrounding water, until its hull implodes. Why, then hundreds of scientists throughout the world spent their lifelong careers studying high-pressure phenomena? Despite all the developments in experimental technologies and instrumentation, modern scientist has very few tools that allow him or her to "grab" two atoms and bring them, in a very controllable way, closer together. Being able to achieve this task means the ability to directly probe interatomic interaction potentials and can cause transformations as dramatic as turning of a common gas into solid metal. Before the reader delves into more advanced topics described later in this book, this introductory chapter aims to explain several elementary, but extremely important concepts in high-pressure science. We will start with a brief discussion of laboratory devices used to produce pressure, address the issue of hydrostaticity, elastic and plastic compression, and will conclude with a short discussion of unique effects of anisotropic stress.

  5. HIGH PRESSURE COAL COMBUSTON KINETICS PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Stefano Orsino

    2005-03-30

    As part of the U.S. Department of Energy (DoE) initiative to improve the efficiency of coal-fired power plants and reduce the pollution generated by these facilities, DOE has funded the High-Pressure Coal Combustion Kinetics (HPCCK) Projects. A series of laboratory experiments were conducted on selected pulverized coals at elevated pressures with the specific goals to provide new data for pressurized coal combustion that will help extend to high pressure and validate models for burnout, pollutant formation, and generate samples of solid combustion products for analyses to fill crucial gaps in knowledge of char morphology and fly ash formation. Two series of high-pressure coal combustion experiments were performed using SRI's pressurized radiant coal flow reactor. The first series of tests characterized the near burner flame zone (NBFZ). Three coals were tested, two high volatile bituminous (Pittsburgh No.8 and Illinois No.6), and one sub-bituminous (Powder River Basin), at pressures of 1, 2, and 3 MPa (10, 20, and 30 atm). The second series of experiments, which covered high-pressure burnout (HPBO) conditions, utilized a range of substantially longer combustion residence times to produce char burnout levels from 50% to 100%. The same three coals were tested at 1, 2, and 3 MPa, as well as at 0.2 MPa. Tests were also conducted on Pittsburgh No.8 coal in CO2 entrainment gas at 0.2, 1, and 2 MPa to begin establishing a database of experiments relevant to carbon sequestration techniques. The HPBO test series included use of an impactor-type particle sampler to measure the particle size distribution of fly ash produced under complete burnout conditions. The collected data have been interpreted with the help of CFD and detailed kinetics simulation to extend and validate devolatilization, char combustion and pollutant model at elevated pressure. A global NOX production sub-model has been proposed. The submodel reproduces the performance of the detailed chemical

  6. Photophysics of organic molecules at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Dean James

    1978-01-01

    The pressure dependence of emission intensities, energies, and lifetimes of several classes of organic compounds in plastic media were investigated over the range 0-140 kilobars. The fluorescence intensity of 9-anthraldehyde, 9-acetylanthracene, and 9-benzoylanthracene increases remarkably with increasing pressure, accompanied by a large red shift in the emission spectrum. For azulene and several derivatives, the efficiency of fluorescence from both the second and first excited singlet states was pressure dependent as was the relative energy of these states. The rate of internal conversion depended strongly on the energy separating the relevant states. The energy and quantum efficiency of fluorescence for fluorenone in crystalline form and in several polymeric matrices was measured as a function of pressure. The quantum yield, ranged from 0.001 at low pressure to a maximum of about 0.1 at high pressure in paraffinic plastics. Fluorescence quantum yields and phosphorescence quantum yields and lifetimes were measured for pyrazine (P) 2,6-dimethylpyrazine and tetramethylpyrazine (TMP) in PMMA over the pessure range 20-120 kbar. An additional emission, which is attributed to excimer fluorescence, was also observed for these samples and for crystalline pyrazine. The phosphorescence radiative lifetime for P and TMP was about 18 ms.

  7. High temperature and pressure electrochemical test station

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2013-01-01

    An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 ◦C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive...... media, as well as localized sampling of gas evolved at the electrodes for gas analysis. A number of safety and engineering design challenges have been addressed. Furthermore, we present a series of electrochemical cell holders that have been constructed in order to accommodate different types of cells......, to the electrochemical characterization of high temperature and pressure alkaline electrolysis cells and the use of pseudo-reference electrodes for the separation of each electrode contribution. A future perspective of various electrochemical processes and devices that can be developed with the use of the established...

  8. Blue emitting organic semiconductors under high pressure

    DEFF Research Database (Denmark)

    Knaapila, Matti; Guha, Suchismita

    2016-01-01

    This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure...... and intermolecular self-organization that typically determine transport and optical emission in π-conjugated oligomers and polymers. In this context, hydrostatic pressure through diamond anvil cells has proven to be an elegant tool to control structure and interactions without chemical intervention. This has been...... and intermolecular interactions on optical excitations, electron–phonon interaction, and changes in backbone conformations. This picture is connected to the optical high pressure studies of other π-conjugated systems and emerging x-ray scattering experiments from polyfluorenes which provides a structure-property map...

  9. High pressure photophysics of organic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Brey, L. A.

    1979-01-01

    High pressure spectroscopic studies on several classes of organic compounds were made both in fluid solution (to 10 kbar) and in polymeric media (to 40 kbar). The first three studies were conducted in fluid solution and concern the effect of solvent viscosity on the nonradiative deactivation rates from electronically excited states. Pressure was utilized to attain high viscosities in organic solvents at room temperature. The primary experimental technique used was fluorescence emission spectroscopy. In the fourth and last study observations were made both in fluid solution and in plastic films. The focus of this study was the effect of pressure on the solvent-chromophore dispersion interaction in several polyenes and the concomitant changes in both the radiative and non-radiative rates from the excited states. Extensive use was made of fluorescence lifetime measurements and excitation spectra. 105 references.

  10. Too Many Americans Have High Blood Pressure, Doctors Warn

    Science.gov (United States)

    ... news/fullstory_163468.html Too Many Americans Have High Blood Pressure, Doctors Warn With February designated National Heart Month, ... physicians warns that too many Americans struggle with high blood pressure. High blood pressure is a major risk factor ...

  11. An numerical analysis of high-temperature helium reactor power plant for co-production of hydrogen and electricity

    Science.gov (United States)

    Dudek, M.; Podsadna, J.; Jaszczur, M.

    2016-09-01

    In the present work, the feasibility of using a high temperature gas cooled nuclear reactor (HTR) for electricity generation and hydrogen production are analysed. The HTR is combined with a steam and a gas turbine, as well as with the system for heat delivery for medium temperature hydrogen production. Industrial-scale hydrogen production using copper-chlorine (Cu-Cl) thermochemical cycle is considered and compared with high temperature electrolysis. Presented cycle shows a very promising route for continuous, efficient, large-scale and environmentally benign hydrogen production without CO2 emissions. The results show that the integration of a high temperature helium reactor, with a combined cycle for electric power generation and hydrogen production, may reach very high efficiency and could possibly lead to a significant decrease of hydrogen production costs.

  12. Advanced Diagnostics for High Pressure Spray Combustion.

    Energy Technology Data Exchange (ETDEWEB)

    Skeen, Scott A.; Manin, Julien Luc; Pickett, Lyle M.

    2014-06-01

    The development of accurate predictive engine simulations requires experimental data to both inform and validate the models, but very limited information is presently available about the chemical structure of high pressure spray flames under engine- relevant conditions. Probing such flames for chemical information using non- intrusive optical methods or intrusive sampling techniques, however, is challenging because of the physical and optical harshness of the environment. This work details two new diagnostics that have been developed and deployed to obtain quantitative species concentrations and soot volume fractions from a high-pressure combusting spray. A high-speed, high-pressure sampling system was developed to extract gaseous species (including soot precursor species) from within the flame for offline analysis by time-of-flight mass spectrometry. A high-speed multi-wavelength optical extinction diagnostic was also developed to quantify transient and quasi-steady soot processes. High-pressure sampling and offline characterization of gas-phase species formed following the pre-burn event was accomplished as well as characterization of gas-phase species present in the lift-off region of a high-pressure n-dodecane spray flame. For the initial samples discussed in this work several species were identified, including polycyclic aromatic hydrocarbons (PAH); however, quantitative mole fractions were not determined. Nevertheless, the diagnostic developed here does have this capability. Quantitative, time-resolved measurements of soot extinction were also accomplished and the novel use of multiple incident wavelengths proved valuable toward characterizing changes in soot optical properties within different regions of the spray flame.

  13. Cobalt ferrite nanoparticles under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Saccone, F. D.; Ferrari, S.; Grinblat, F.; Bilovol, V. [Instituto de Tecnologías y Ciencias de la Ingeniería, “Ing. H. Fernández Long,” Av. Paseo Colón 850 (1063), Buenos Aires (Argentina); Errandonea, D., E-mail: daniel.errandonea@uv.es [Departamento de Fisica Aplicada, Institut Universitari de Ciència dels Materials, Universitat de Valencia, c/ Doctor Moliner 50, E-46100 Burjassot, Valencia (Spain); Agouram, S. [Departamento de Física Aplicada y Electromagnetismo, Universitat de València, 46100 Burjassot, Valencia (Spain)

    2015-08-21

    We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B{sub 0} = 204 GPa) is considerably larger than the value previously reported for bulk CoFe{sub 2}O{sub 4} (B{sub 0} = 172 GPa). In addition, when the pressure medium becomes non-hydrostatic and deviatoric stresses affect the experiments, there is a noticeable decrease of the compressibility of the studied sample (B{sub 0} = 284 GPa). After decompression, the cobalt ferrite lattice parameter does not revert to its initial value, evidencing a unit cell contraction after pressure was removed. Finally, Raman spectroscopy provides information on the pressure dependence of all Raman-active modes and evidences that cation inversion is enhanced by pressure under non-hydrostatic conditions, being this effect not fully reversible.

  14. Nanoshells as a high-pressure gauge

    Science.gov (United States)

    Tempere, Jacques; van den Broeck, Nick; Putteneers, Katrijn; Silvera, Isaac

    2012-02-01

    Nanoshells, consisting of multiple spherical layers, have an extensive list of applications, usually performing the function of a probe. We add a new application to this list in the form of a high-pressure gauge in a Diamond Anvil Cell (DAC). In a DAC, where high pressures are reached by pressing two diamonds together, existing gauges fail at higher pressures because of calibration difficulties and obscuring effects in the diamonds. The nanoshell gauge does not face this issue since its optical spectrum can be engineered by altering the thickness of its layers. Furthermore their properties are measured by broad band optical transmission spectroscopy leading to a very large signal-to-noise ratio even in the multi-megabar pressure regime where ruby measurements become challenging. Theoretical calculations based on the Maxwell equations in a spherical geometry combined with the Vinet equation of state show that a three-layer geometry (SiO2-Au-SiO2) indeed has a measurable pressure-dependent optical response desirable for gauges.

  15. Teaming Up Against High Blood Pressure

    Centers for Disease Control (CDC) Podcasts

    2012-09-04

    This podcast is based on the September 2012 CDC Vital Signs report. A team-based approach by patients, health care systems, and health care providers is one of the best ways to treat uncontrolled high blood pressure.  Created: 9/4/2012 by Centers for Disease Control and Prevention (CDC).   Date Released: 9/4/2012.

  16. High Pressure Inactivation of HAV within Mussels

    Science.gov (United States)

    The potential of hepatitis A virus (HAV) to be inactivated within Mediterranean mussels (Mytilus galloprovincialis) and blue mussels (Mytilus edulis) by high pressure processing was evaluated. HAV was bioaccumulated within mussels to approximately 6-log10 PFU by exposure of mussels to HAV-contamina...

  17. High pressure and synchrotron radiation satellite workshop

    Energy Technology Data Exchange (ETDEWEB)

    Bass, J.; Guignot, N.; Morard, G.; Mezouar, M.; Andrault, D.; Bolfan-Casanova, N.; Sturhahn, W.; Daniel, I.; Reynard, B.; Simionovici, A.; Sanchez Valle, C.; Martinez, I.; Kantor, I.; Dubrovinsky, I.; Mccammon, C.; Dubrovinskaia, N.; Kurnosiv, A.; Kuznetsov, A.; Goncharenko, I.; Loubeyre, P.; Desgreniers, S.; Weck, G.; Yoo, C.S.; Iota, V.; Park, J.; Cynn, H.; Gorelli, F.; Toulemonde, P.; Machon, D.; Merlen, A.; San Miguel, A.; Amboage, M.; Aquilanti, G.; Mathon, O.; Pascarelli, S.; Itie, J.P.; Mcmillan, P.F.; Trapananti, A.; Di Cicco, A.; Panfilis, S. de; Filipponi, A.; Kreisel, J.; Bouvier, P.; Dkhil, B.; Chaabane, B.; Rosner, H.; Koudela, D.; Schwarz, U.; Handestein, A.; Hanfland, M.; Opahle, I.; Koepernik, K.; Kuzmin, M.; Mueller, K.H.; Mydosh, J.; Richter, M.; Hejny, C.; Falconi, S.; Lundegaard, L.F.; Mcmahon, M.I; Loa, I.; Syassen, K.; Wang, X.; Roth, H.; Lorenz, T.; Farber Daniel, I.; Antonangeli Daniele, I.; Krisch, M.; Badro, J.; Fiquet, G.; Occelli, F.; Mao, W.L.; Mao, H.K.; Eng, P.; Kao, C.C.; Shu, J.F.; Hemley, R.J.; Tse, J.S.; Yao, Y.; Deen, P.P.; Paolasini, I.; Braithwaite, D.; Kernavanois, N.; Lapertot, G.; Rupprecht, K.; Leupold, O.; Ponkratz, U.; Wortmann, G.; Beraud, A.; Krisch, M.; Farber, D.; Antonangeli, D.; Aracne, C.; Zarestky, J.L.; Mcqueeney, R.; Mathon, O.; Baudelet, F.; Decremps, F.; Itie, J.P.; Nataf, I.; Pascarelli, S.; Polian, A

    2006-07-01

    The workshop is dedicated to recent advances on science at high pressure at third generation synchrotron sources. A variety of experiments using synchrotron radiation techniques including X-ray diffraction, EXAFS (extended X-ray absorption fine structure), inelastic X-ray scattering, Compton scattering and Moessbauer spectroscopy of crystalline, liquid or amorphous samples, are reported. This document gathers the abstracts of the presentations.

  18. Ultra-High Sensitivity Techniques for the Determination of 3 He /4 He Abundances in Helium by Accelerator Mass Spectrometry

    Science.gov (United States)

    Mumm, H. P.; Huber, M.; Bauder, W.; Abrams, N.; Deibel, C.; Huffer, C.; Huffman, P.; Schelhammer, K.; Janssens, R.; Jiang, C.; Scott, R.; Pardo, R.; Rehm, K.; Vondrasek, R.; Swank, C.; O'Shaughnessy, C.; Paul, M.; Yang, L.

    2017-01-01

    We report the development of an Accelerator Mass Spectrometry technique to measure the 3He/4He isotopic ratio using a radio frequency (RF) discharge source and the ATLAS facility at Argonne National Laboratory. Control over 3He/4He ratio in helium several orders of magnitude lower than natural abundance is critical for neutron lifetime and source experiments using liquid helium. Due to low ultimate beam currents, the ATLAS accelerator and beam line were tuned using a succession of species of the same M/q. A unique RF source was developed for the experiment due to large natural 3He backgrounds. Analog H_3 + and DH + molecular ions are eliminated by dissociation via a gold stripper foil near the detector. The stripped ions were dispersed in a magnetic spectrograph and 3He2 + ions counted in the focal plane detector. This technique is sensitive to 3 He /4 He ratios in the regime of 10-12 with backgrounds that appear to be below 10-14. The techniques used to reduce the backgrounds and remaining outstanding problems will be presented along with results from measurements on high purity 4He samples.

  19. UO2 and PuO2 utilization in high temperature engineering test reactor with helium coolant

    Science.gov (United States)

    Waris, Abdul; Aji, Indarta K.; Novitrian, Pramuditya, Syeilendra; Su'ud, Zaki

    2016-03-01

    High temperature engineering test reactor (HTTR) is one of high temperature gas cooled reactor (HTGR) types which has been developed by Japanese Atomic Energy Research Institute (JAERI). The HTTR is a graphite moderator, helium gas coolant, 30 MW thermal output and 950 °C outlet coolant temperature for high temperature test operation. Original HTTR uses UO2 fuel. In this study, we have evaluated the use of UO2 and PuO2 in form of mixed oxide (MOX) fuel in HTTR. The reactor cell calculation was performed by using SRAC 2002 code, with nuclear data library was derived from JENDL3.2. The result shows that HTTR can obtain its criticality condition if the enrichment of 235U in loaded fuel is 18.0% or above.

  20. Kinetic and microstructural studies of thermal decomposition in uranium mononitride compacts subjected to heating in high-purity helium

    Science.gov (United States)

    Lunev, A. V.; Mikhalchik, V. V.; Tenishev, A. V.; Baranov, V. G.

    2016-07-01

    Although uranium mononitride has a high melting point (≈3100 K), it often decomposes well below this temperature. The threshold and kinetics of thermal decomposition depend on samples' chemical content and on gas environment. However, most experiments with uranium nitride samples were done so far in vacuum conditions and did not allow thorough examination of reaction kinetics at high temperatures. This research focuses on studying the different stages of thermal decomposition in uranium nitride samples subjected to heating in helium. Mass loss and thermal effects are identified with simultaneous thermal analysis (STA), while scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used to register phase and compositional changes. Thermal decomposition in uranium nitride samples is found to be a multi-stage process with the final stage characterized by uranium vaporization. The results are useful for estimating the high-temperature behaviour of uranium nitride fuel during its fabrication and performance in some of Gen IV reactors.

  1. Helium release during shale deformation: Experimental validation

    Science.gov (United States)

    Bauer, Stephen J.; Gardner, W. Payton; Heath, Jason E.

    2016-07-01

    This work describes initial experimental results of helium tracer release monitoring during deformation of shale. Naturally occurring radiogenic 4He is present in high concentration in most shales. During rock deformation, accumulated helium could be released as fractures are created and new transport pathways are created. We present the results of an experimental study in which confined reservoir shale samples, cored parallel and perpendicular to bedding, which were initially saturated with helium to simulate reservoir conditions, are subjected to triaxial compressive deformation. During the deformation experiment, differential stress, axial, and radial strains are systematically tracked. Release of helium is dynamically measured using a helium mass spectrometer leak detector. Helium released during deformation is observable at the laboratory scale and the release is tightly coupled to the shale deformation. These first measurements of dynamic helium release from rocks undergoing deformation show that helium provides information on the evolution of microstructure as a function of changes in stress and strain.

  2. Foaming Glass Using High Pressure Sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    Foam glass is a high added value product which contributes to waste recycling and energy efficiency through heat insulation. The foaming can be initiated by a chemical or physical process. Chemical foaming with aid of a foaming agent is the dominant industrial process. Physical foaming has two...... microscope above maximum foaming temperature gives a suitable foaming temperature for the remaining samples. We show that the foaming kinetics depend on the type of gas and the pressure. A critical pressure of around 20 MPa is found to give the largest expansion for all gasses. Samples are obtained with 100...

  3. Recombination-cascade X-ray spectra of highly charged helium-like ions

    Science.gov (United States)

    Pradhan, A. K.

    1985-01-01

    It is shown that the relative intensity distribution among the X-ray spectral lines of helium-like ions from the n = 2 states produced through recombination processes such as radiative and charge transfer recombination may be given by considering in detail the radiative cascades following recombination. Model calculations are presented with predicted line ratios for Ar XVII and Fe XXV in recombination-dominated noncoronal plasmas. In particular, compared to coronal intensities, the singlet resonance line (w) should be much weaker relative to the triplet intercombination (x, y) and forbidden (z) lines, yielding large values for the ratio G = (x + y + z)/w. Accurate configuration interaction type wave functions are employed to calculate the eigenenergies, transition probabilities, and cascade coefficients. Certain relevant tokamak and astrophysical observations are discussed.

  4. (Ultra high pressure homogenization for continuous high pressure sterilization of pumpable foods - a review

    Directory of Open Access Journals (Sweden)

    Erika eGeorget

    2014-08-01

    Full Text Available Bacterial spores have a strong resistance to both chemical and physical hurdles and create a risk for food industry which has been tackled by applying high thermal intensity treatments to sterilize food. These strong thermal treatments lead to reduction of the organoleptic and nutritional properties of food and alternative are actively searched for. Innovative hurdles offer an alternative to inactivate bacterial spores. In particular, recent technological developments have enabled a new generation of high pressure homogenizer working at pressures up to 400 MPa and thus opening new opportunities for high pressure sterilization of foods. In this short review, we summarize the work conducted on (ultra-high pressure homogenization (UHPH to inactivate endospores in model and food systems. Specific attention is given to process parameters (pressure, inlet and valve temperatures. This review gathers the current state of the art and underlines the potential of UHPH sterilization of pumpable foods while highlighting the needs for future work.

  5. Zeeman Effect in Ruby at High Pressures

    Science.gov (United States)

    Dan, Ioana

    2012-02-01

    We have developed a versatile fiber-coupled system for magneto-optical spectroscopy measurements at high pressure. The system is based on a miniature Cu-alloy Diamond Anvil Cell (from D'Anvils, Ltd) fitted with a custom-designed He gas-actuated membrane for in-situ pressure control, and coupled with a He transfer cryostat incorporating a superconducting magnet (from Quantum Designs). This system allows optical measurements (Raman, photoluminescence, reflectivity) within wide ranges of pressures (up to 100GPa), temperatures (4.2-300K) and magnetic fields (0-9T). We employ this system to examine the effect of pressure and non-hydrostatic stress on the Zeeman split d-d transitions of Cr^3+ in ruby (Al2O3: Cr^3+). We determine the effect of pressure and non-hydrostaticity on the trigonal crystal field in this material, and discuss the use of the Zeman-split ruby fluorescence as a possible probe for deviatoric stresses in diamond anvil cell experiments.

  6. High Pressure Behavior of FeOOH

    Science.gov (United States)

    Reagan, M. M.; Gleason, A. E.; Mao, W. L.

    2013-12-01

    Understanding the stability and properties of simple hydroxides at high pressures and temperatures offers an important first step toward quantifying more complex hydrogen-bearing compounds relevant to the Earth's interior. We focus on iron-oxy-hydroxides because they may be an important Fe and water bearing component in the deep Earth. Goethite (α-FeOOH) transforms to a high-pressure phase, ɛ-FeOOH, which is isostructural with δ-AlOOH, a material which may transport hydrogen to the core-mantle boundary. Here we present XES spectroscopy data of powder samples of synthesized alpha-FeOOH, beta-FeOOH and gamma-FeOOH monitoring their electronic spin transition. The samples was loaded into a Beryllium gasket, where a 50 micron hole served as the sample chamber with 300 micron culet diamond paired with a beveled 150 micron diamond in a diamond-anvil cell (DAC) without a pressure transmitting medium. Pressure was determined using ruby fluorescence (Mao et al. 1978). Using the incident X-ray energy centered at 11.3 KeV from the Advanced Photon Source, beam line HPCAT 16-ID-D, we measured Fe K-β 13 emission to pressures greater than 73 GPa. For alpha-FeOOH, we saw a clear shift in the main peak to lower energy, and an increasingly diminishing K beta prime peak intensity, indicating the sample was undergoing an electronic spin transition. The K beta prime peak completely disappeared at a pressure greater than 73 GPa. Beta-FeOOH showed no evidence of the beginnings of a spin transition, while gamma- FeOOH underwent an incomplete transition.

  7. $\\mu$SR-Measurements under High Pressure and at Low Temperatures

    CERN Multimedia

    2002-01-01

    High pressure causes changes in the volume available to each atom in a solid and will therefore influence local properties like the electronic charge and spin densities and, in the case of magnetic materials, the spin ordering.\\\\ \\\\ The positive muon is known to be an interesting probe particle for the study of certain problems in magnetism. It has in fact been used for one high pressure experiment earlier in CERN, but the present experiments aim at more systematic studie For this purpose it is necessary to carry out pressure experiments at low temperatures. The new experiments use a helium gas pressure system, which covers the temperature range 10-300 K at pressures up to 14 Kbar.\\\\ \\\\ Experiments are in progress on \\item 1)~~~~Ferromagnetic metals like Fe, Co, Ni where the pressure dependence of the local magnetic field ~~~is studied at 77 K and at room temperature. \\item 2)~~~~Knight shifts in semimetals, where in the case of Sb strong variations with temperature and ~~~pressure are observed. \\end{enumerat...

  8. Research and development of a high-temperature helium-leak detection system (joint research). Part 1 survey on leakage events and current leak detection technology

    Energy Technology Data Exchange (ETDEWEB)

    Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Urakami, Masao; Saisyu, Sadanori [Japan Atomic Power Co., Tokyo (Japan)

    2003-03-01

    In High Temperature Gas-cooled Reactors (HTGR), the detection of leakage of helium at an early stage is very important for the safety and stability of operations. Since helium is a colourless gas, it is generally difficult to identify the location and the amount of leakage when very little leakage has occurred. The purpose of this R and D is to develop a helium leak detection system for the high temperature environment appropriate to the HTGR. As the first step in the development, this paper describes the result of surveying leakage events at nuclear facilities inside and outside Japan and current gas leakage detection technology to adapt optical-fibre detection technology to HTGRs. (author)

  9. LOX Tank Helium Removal for Propellant Scavenging

    Science.gov (United States)

    Chato, David J.

    2009-01-01

    System studies have shown a significant advantage to reusing the hydrogen and oxygen left in these tanks after landing on the Moon in fuel cells to generate power and water for surface systems. However in the current lander concepts, the helium used to pressurize the oxygen tank can substantially degrade fuel cell power and water output by covering the reacting surface with inert gas. This presentation documents an experimental investigation of methods to remove the helium pressurant while minimizing the amount of the oxygen lost. This investigation demonstrated that significant quantities of Helium (greater than 90% mole fraction) remain in the tank after draining. Although a single vent cycle reduced the helium quantity, large amounts of helium remained. Cyclic venting appeared to be more effective. Three vent cycles were sufficient to reduce the helium to small (less than 0.2%) quantities. Two vent cycles may be sufficient since once the tank has been brought up to pressure after the second vent cycle the helium concentration has been reduced to the less than 0.2% level. The re-pressurization process seemed to contribute to diluting helium. This is as expected since in order to raise the pressure liquid oxygen must be evaporated. Estimated liquid oxygen loss is on the order of 82 pounds (assuming the third vent cycle is not required).

  10. Yoga Called Good Medicine for High Blood Pressure

    Science.gov (United States)

    ... fullstory_162446.html Yoga Called Good Medicine for High Blood Pressure People who added this practice to a healthy ... elevated blood pressure] are likely to develop hypertension [high blood pressure] unless they improve their lifestyle," said study author ...

  11. Is sodium a superconductor under high pressure?

    Science.gov (United States)

    Tutchton, Roxanne; Chen, Xiaojia; Wu, Zhigang

    2017-01-07

    Superconductivity has been predicted or measured for most alkali metals under high pressure, but the computed critical temperature (Tc) of sodium (Na) at the face-centered cubic (fcc) phase is vanishingly low. Here we report a thorough, first-principles investigation of superconductivity in Na under pressures up to 260 GPa, where the metal-to-insulator transition occurs. Linear-response calculations and density functional perturbation theory were employed to evaluate phonon distributions and the electron-phonon coupling for bcc, fcc, cI16, and tI19 Na. Our results indicate that the maximum electron-phonon coupling parameter, λ, is 0.5 for the cI16 phase, corresponding to a theoretical peak in the critical temperature at Tc≈1.2 K. When pressure decreases or increases from 130 GPa, Tc drops quickly. This is mainly due to the lack of p-d hybridization in Na even at 260 GPa. Since current methods based on the Eliashberg and McMillian formalisms tend to overestimate the Tc (especially the peak values) of alkali metals, we conclude that under high pressure-before the metal-to-insulator transition at 260 GPa-superconductivity in Na is very weak, if it is measurable at all.

  12. Picosecond High Pressure Gas Switch experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cravey, W.R.; Freytag, E.K.; Goerz, D.A.; Poulsen, P.; Pincosy, P.A.

    1993-08-01

    A high Pressure Gas Switch has been developed and tested at LLNL. Risetimes on the order of 200 picoseconds have been observed at 1 kHz prf and 1 atmosphere pressures. Calculations show that switching closure times on the order of tens of picoseconds can be achieved at higher pressures and electric fields. A voltage hold-off of 1 MV/cm has been measured at 10 atmospheres and several MV/cm appears possible with the HPGS. With such high electric field levels, energy storage of tens of Joules in a reasonably sized package is achievable. Initial HPGS performance has been characterized using the WASP pulse generator at LLNL. A detailed description of the switch used for initial testing is given. Switch recovery times of 1-ms have been measured at 1 atmosphere. Data on the switching uniformity, voltage hold-off recovery, and pulse repeatability, is presented. In addition, a physics switch model is described and results are compared with experimental data. Modifications made to the WASP HV pulser in order to drive the HPGS will also be discussed. Recovery times of less than 1 ms were recorded without gas flow in the switch chambers. Low pressure synthetic air was used as the switch dielectric. Longer recovery times were required when it was necessary to over-voltage the switch.

  13. Strain engineered pyrochlore at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rittman, Dylan R.; Turner, Katlyn M.; Park, Sulgiye; Fuentes, Antonio F.; Park, Changyong; Ewing, Rodney C.; Mao, Wendy L.

    2017-05-22

    Strain engineering is a promising method for next-generation materials processing techniques. Here, we use mechanical milling and annealing followed by compression in diamond anvil cell to tailor the intrinsic and extrinsic strain in pyrochlore, Dy2Ti2O7 and Dy2Zr2O7. Raman spectroscopy, X-ray pair distribution function analysis, and X-ray diffraction were used to characterize atomic order over short-, medium-, and long-range spatial scales, respectively, under ambient conditions. Raman spectroscopy and X-ray diffraction were further employed to interrogate the material in situ at high pressure. High-pressure behavior is found to depend on the species and concentration of defects in the sample at ambient conditions. Overall, we show that defects can be engineered to lower the phase transformation onset pressure by ~50% in the ordered pyrochlore Dy2Zr2O7, and lower the phase transformation completion pressure by ~20% in the disordered pyrochlore Dy2Zr2O7. These improvements are achieved without significantly sacrificing mechanical integrity, as characterized by bulk modulus.

  14. Molecular Dynamics Simulations of Helium Behaviour in Titanium Crystals

    Institute of Scientific and Technical Information of China (English)

    SUN Tie-Ying; LONG Xing-Gui; WANG Jun; HOU Qing; WU Zhong-Cheng; PENG Shu-Ming; LUO Shun-Zhong

    2008-01-01

    Molecular dynamics simulations are performed to investigate the behaviour of helium atoms in titanium at a temperature of 300 K.The nucleation and growth of helium bubble has been simulated up to 50 helium atoms.The approach to simulate the bubble growth is to add helium atoms one by one to the bubble and let the system evolve.The titanium cohesion is based on the tight binding scheme derived from the embedded atom method,and the helium-titanium interaction is characterized by fitted potential in the form of a Lennard-Jones function.The pressure in small helium bubbles is approximately calculated.The simulation results show that the pressure will decrease with the increasing bubble size,while increase with the increasing helium atoms.An analytic function about the quantitative relationship of the pressure with the bubble size and number of helium atoms is also fitted.

  15. Characterization and antimicrobial efficacy against E. coli of a helium/air plasma at atmospheric pressure created in a plastic package

    Science.gov (United States)

    Connolly, J.; Valdramidis, V. P.; Byrne, E.; Karatzas, K. A.; Cullen, P. J.; Keener, K. M.; Mosnier, J. P.

    2013-01-01

    A plasma source, sustained by the application of a floating high voltage (±15 kV) to parallel-plate electrodes at 50 Hz, has been achieved in a helium/air mixture at atmospheric pressure (P = 105 Pa) contained in a zip-locked plastic package placed in the electrode gap. Some of the physical and antimicrobial properties of this apparatus were established with a view to ascertain its performance as a prototype for the disinfection of fresh produce. The current-voltage (I-V) and charge-voltage (Q-V) characteristics of the system were measured as a function of gap distance d, in the range (3 × 103 ⩽ Pd ⩽ 1.0 × 104 Pa m). The electrical measurements showed this plasma source to exhibit the characteristic behaviour of a dielectric barrier discharge in the filamentary mode and its properties could be accurately interpreted by the two-capacitance in series model. The power consumed by the discharge and the reduced field strength were found to decrease quadratically from 12.0 W to 4.5 W and linearly from 140 Td to 50 Td, respectively, in the range studied. Emission spectra of the discharge were recorded on a relative intensity scale and the dominant spectral features could be assigned to strong vibrational bands in the 2+ and 1- systems of N2 and N_2^+ , respectively, with other weak signatures from the NO and OH radicals and the N+, He and O atomic species. Absolute spectral intensities were also recorded and interpreted by comparison with the non-equilibrium synthetic spectra generated by the computer code SPECAIR. At an inter-electrode gap of 0.04 m, this comparison yielded typical values for the electron, vibrational and translational (gas) temperatures of (4980 ± 100) K, (2700 ± 200) K and (300 ± 100) K, respectively and an electron density of 1.0 × 1017 m-3. A Boltzmann plot also provided a value of (3200 ± 200 K) for the vibrational temperature. The antimicrobial efficacy was assessed by studying the resistance of both Escherichia coli K12 its isogenic

  16. A Neutron Scattering Study of Collective Excitations in Superfluid Helium

    DEFF Research Database (Denmark)

    Graf, E. H.; Minkiewicz, V. J.; Bjerrum Møller, Hans

    1974-01-01

    Extensive inelastic-neutron-scattering experiments have been performed on superfluid helium over a wide range of energy and momentum transfers. A high-resolution study has been made of the pressure dependence of the single-excitation scattering at the first maximum of the dispersion curve over...... of the multiexcitation scattering was also studied. It is shown that the multiphonon spectrum of a simple Debye solid with the phonon dispersion and single-excitation cross section of superfluid helium qualitatively reproduces these data....

  17. Inspection technology for high pressure pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae H.; Lee, Jae C.; Eum, Heung S.; Choi, Yu R.; Moon, Soon S.; Jang, Jong H

    2000-02-01

    Various kinds of defects are likely to be occurred in the welds of high pressure pipes in nuclear power plants. Considering the recent accident of Zuruga nuclear power plant in Japan, reasonable policy is strongly requested for the high pressure pipe integrity. In this study, we developed the technologies to inspect pipe welds automatically. After development of scanning robot prototype in the first research year, we developed and implemented the algorithm of automatic tracking of the scanning robot along the weld line of the pipes. We use laser slit beam on weld area and capture the image using digital camera. Through processing of the captures image, we finally determine the weld line automatically. In addition, we investigated a new technology on micro systems for developing micro scanning robotic inspection of the pipe welds. The technology developed in this study is being transferred to the industry. (author)

  18. High-pressure investigations of Earth's interior

    Science.gov (United States)

    Jackson, Jennifer

    2007-03-01

    In the first half of the talk, the electronic structure of iron in ferromagnesium silicate perovskite will be discussed. Knowledge of iron valences and spin states in silicate perovskite is relevant to our understanding of the physical and chemical properties of Earth's lower mantle such as transport properties, mechanical behavior, and element partitioning. In this study, we have measured the electronic structure of the iron component of an aluminous Fe-bearing silicate perovskite sample, (Mg0.88Fe0.09)(Si0.94Al0.10)O3, close to a pyrolite composition, using synchrotron M"ossbauer spectroscopy (SMS) and laser heated diamond anvil cells at high-pressure and temperatures at beamline 3-ID of the Advanced Photon Source. Evaluation of the spectra provided the isomer shift and the quadrupole splitting of the iron component in silicate perovskite, which gives information on valence and spin states under lower mantle conditions. In the second half of the talk, experiments on the melting curve of iron at high-pressures will be presented. Seismological observations indicate that Earth's iron-dominated core consists of a solid inner region surrounded by a liquid outer core. Previously, melting studies of iron metal at high-pressures and temperatures were performed by shock-compression, resistive- and laser-heating in diamond anvil cells using visual observations or synchrotron x-ray diffraction and theoretical methods. However, the melting curve of iron is still controversial. Here, we will present a new method of detecting the solid-liquid phase boundary of iron at high-pressure using ^57Fe SMS. The characteristic SMS time signature is observed by fast detectors and vanishes suddenly when melting occurs. This process is described by the Lamb-M"ossbauer factor f = exp(-k^2), where k is the wave number of the resonant x-rays and is the mean-square displacement of the iron atoms.

  19. Modeling High Pressure Micro Hollow Cathode Discharges

    Science.gov (United States)

    2007-11-02

    cathode discharge excimer lamps , Phys. Plasmas 7, 286 (2000). [3] RH Stark and KH Schoenbach, Direct high pressure glow discharges, J. Appl. Phys...temperature profiles in argon glow discharges, J. Appl. Phys. 88, 2234 (2000) [8] M. Moselhy, W. Shi, R. Stark, A flat glow discharge excimer radiation...MHCD acts as a plasma cathode for a third electrode (anode). Some experimental results in this geometry are available for argon and for air from the

  20. High Pressure Multicomponent Adsorption in Porous Media

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan

    1999-01-01

    We analyse adsorption of a multicomponent mixture at high pressure on the basis of the potential theory of adsorption. The adsorbate is considered as a segregated mixture in the external field produced by a solid adsorbent. we derive an analytical equation for the thickness of a multicomponent film...... close to a dew point. This equation (asymptotic adsorption equation, AAE) is a first order approximation with regard to the distance from a phase envelope....

  1. Design of high power helium turbo-expander%大功率氦气透平膨胀机的设计

    Institute of Scientific and Technical Information of China (English)

    孙郁; 孙立佳; 程进杰; 任小坤; 张武

    2015-01-01

    介绍了大型氦气制冷机系统应用中的关键设备,大功率氦气透平膨胀机的设计。在设计中,充分考虑了大功率透平大流量,高压降的特点,对转子、气体轴承系统进行了设计、校核及优化。同时对通流部分的气动性能进行了模拟计算,得到了较高的通流效率。试验结果表明,透平膨胀机满足了10 kW@20 K制冷机系统要求,设备运行稳定。%Design of high power turbo-expander was introduced which was the key equipment in large helium refrigerator .Large flowrate and pressure difference were considered for the design of the rotor system and gas bearing .Numerical simulation was performed to analyze aerodynamic performance on the flow area in order to achieve a high efficiency .According to the experimental results , turbo-expander designed satis-fied the requirement of 10 kW@20 K refrigerator with good stability .

  2. Structures of xenon oxides at high pressures

    Science.gov (United States)

    Worth, Nicholas; Pickard, Chris; Needs, Richard; Dewaele, Agnes; Loubeyre, Paul; Mezouar, Mohamed

    2014-03-01

    For many years, it was believed that noble gases such as xenon were entirely inert. It was only in 1962 that Bartlett first synthesized a compound of xenon. Since then, a number of other xenon compounds, including oxides, have been synthesized. Xenon oxides are unstable under ambient conditions but have been predicted to stabilize under high pressure. Here we present the results of a combined theoretical and experimental study of xenon oxides at pressures of 80-100 GPa. We have synthesized new xenon oxides at these pressures and they have been characterized with X-ray diffraction and Raman spectroscopy. Calculations were performed with a density-functional theory framework. We have used the ab-initio random structure searching (AIRSS) method together with a data-mining technique to determine the stable compounds in the xenon-oxygen system in this pressure range. We have calculated structural and optical properties of these phases, and a good match between theoretical and experimental results has been obtained. Funding for computational research provided by the engineering and physical sciences research council (EPSRC; UK). Computing resources provided by Cambridge HPC and HECToR. X-ray diffraction experiments performed at ESRF.

  3. 7 CFR 58.219 - High pressure pumps and lines.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false High pressure pumps and lines. 58.219 Section 58.219....219 High pressure pumps and lines. High pressure lines may be cleaned-in-place and shall be of such construction that dead ends, valves and the high pressure pumps can be disassembled for hand cleaning. The...

  4. Prediction of Production Power for High-pressure Hydrogen by High-pressure Water Electrolysis

    Science.gov (United States)

    Kyakuno, Takahiro; Hattori, Kikuo; Ito, Kohei; Onda, Kazuo

    Recently the high attention for fuel cell electric vehicle (FCEV) is pushing to construct the hydrogen supplying station for FCEV in the world. The hydrogen pressure supplied at the current test station is intended to be high for increasing the FCEV’s driving distance. The water electrolysis can produce cleanly the hydrogen by utilizing the electricity from renewable energy without emitting CO2 to atmosphere, when it is compared to be the popular reforming process of fossil fuel in the industry. The power required for the high-pressure water electrolysis, where water is pumped up to high-pressure, may be smaller than the power for the atmospheric water electrolysis, where the produced atmospheric hydrogen is pumped up by compressor, since the compression power for water is much smaller than that for hydrogen gas. In this study the ideal water electrolysis voltage up to 70MPa and 523K is estimated referring to both the results by LeRoy et al up to 10MPa and 523K, and to the latest steam table. By using this high-pressure water electrolysis voltage, the power required for high-pressure hydrogen produced by the high-pressure water electrolysis method is estimated to be about 5% smaller than that by the atmospheric water electrolysis method, by assuming the compressor and pump efficiency of 50%.

  5. Double ionization of helium by highly-charged-ion impact analyzed within the frozen-correlation approximation

    Energy Technology Data Exchange (ETDEWEB)

    Ciappina, M. F.; Kirchner, T.; Schulz, M. [ICFO-Institut de Ciences Fotoniques, 08860 Castelldefels (Barcelona) (Spain); Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3 (Canada); Department of Physics and LAMOR, Missouri University of Science and Technology, Rolla, MO 65409 (United States)

    2011-09-15

    We apply the frozen-correlation approximation (FCA) to analyze double ionization of helium by energetic highly charged ions. In this model the double ionization amplitude is represented in terms of single ionization amplitudes, which we evaluate within the continuum distorted wave-eikonal initial state (CDW-EIS) approach. Correlation effects are incorporated in the initial and final states, but are neglected during the time the collision process takes place. We implement the FCA using the Monte Carlo event generator technique, which allows us to generate theoretical event files and to compare theory and experiment using the same analysis tools. The comparison with previous theoretical results and with experimental data demonstrates, on the one hand, the validity of our earlier simple models to account for higher-order mechanisms, and, on the other hand, the robustness of the FCA.

  6. One- and two-photon spectroscopy of highly excited states of alkali-metal atoms on helium nanodroplets.

    Science.gov (United States)

    Pifrader, Alexandra; Allard, Olivier; Auböck, Gerald; Callegari, Carlo; Ernst, Wolfgang E; Huber, Robert; Ancilotto, Francesco

    2010-10-28

    Alkali-metal atoms captured on the surface of superfluid helium droplets are excited to high energies (≈3 eV) by means of pulsed lasers, and their laser-induced-fluorescence spectra are recorded. We report on the one-photon excitation of the (n+1)p←ns transition of K, Rb, and Cs (n=4, 5, and 6, respectively) and on the two-photon one-color excitation of the 5d←5s transition of Rb. Gated-photon-counting measurements are consistent with the relaxation rates of the bare atoms, hence consistent with the reasonable expectation that atoms quickly desorb from the droplet and droplet-induced relaxation need not be invoked.

  7. Effect of discharge polarity on the propagation of atmospheric-pressure helium plasma jets and the densities of OH, NO, and O radicals.

    Science.gov (United States)

    Yonemori, Seiya; Ono, Ryo

    2015-06-01

    The atmospheric-pressure helium plasma jet is an emerging technology for plasma biomedical applications. In this paper, the authors focus on the effect of discharge polarity on propagation of the discharge and the densities of OH, NO, and O radicals. The plasma jet is applied to a glass surface placed on a grounded metal plate. Positive or negative voltage pulses with 25 μs duration, 8 kV amplitude, and 10 kpps repetition rate are used for the plasma jet. The plasma propagation is measured using a short-gated ICCD camera. The light emission intensity of the discharge generated at the rising phase of the voltage pulse is approximately equivalent for both polarities, while that generated during the falling phase is much higher for the negative discharge than the positive one. The shape of the discharge changes with the discharge polarity. The OH, NO, and O densities in the plasma jet are also measured for both polarities. It is found that the OH density is almost the same regardless the discharge polarity. Conversely, the negative discharge produces more O atoms and the positive discharge produces more NO molecules. These results indicate that the polarity of the discharge affects the densities of some reactive species produced in the plasma jet.

  8. HyRec: A fast and highly accurate primordial hydrogen and helium recombination code

    CERN Document Server

    Ali-Haïmoud, Yacine

    2010-01-01

    We present a state-of-the-art primordial recombination code, HyRec, including all the physical effects that have been shown to significantly affect recombination. The computation of helium recombination includes simple analytic treatments of hydrogen continuum opacity in the He I 2 1P - 1 1S line, the He I] 2 3P - 1 1S line, and treats feedback between these lines within the on-the-spot approximation. Hydrogen recombination is computed using the effective multilevel atom method, virtually accounting for an infinite number of excited states. We account for two-photon transitions from 2s and higher levels as well as frequency diffusion in Lyman-alpha with a full radiative transfer calculation. We present a new method to evolve the radiation field simultaneously with the level populations and the free electron fraction. These computations are sped up by taking advantage of the particular sparseness pattern of the equations describing the radiative transfer. The computation time for a full recombination history i...

  9. Low-Power Miniaturized Helium Dielectric Barrier Discharge Photoionization Detectors for Highly Sensitive Vapor Detection.

    Science.gov (United States)

    Zhu, Hongbo; Zhou, Menglian; Lee, Jiwon; Nidetz, Robert; Kurabayashi, Katsuo; Fan, Xudong

    2016-09-06

    This paper presents the design, fabrication, and characterization of a microhelium dielectric barrier discharge photoionization detector (μHDBD-PID) on chip with dimensions of only ∼15 mm × ∼10 mm × ∼0.7 mm and weight of only ∼0.25 g. It offers low power consumption (4 orders of magnitude), and maintenance-free operation. Furthermore, the μHDBD-PID can be driven with a miniaturized (∼5 cm × ∼2.5 cm × ∼2.5 cm), light (22 g), and low cost (∼$2) power supply with only 1.5 VDC input. The dependence of the μHDBD-PID performance on bias voltage, auxiliary helium flow rate, carrier gas flow rate, and temperature was also systematically investigated. Finally, the μHDBD-PID was employed to detect permanent gases and a sublist of the EPA 8260 standard reagents that include 51 analytes. The μHDBD-PID developed here can have a broad range of applications in portable and microgas chromatography systems for in situ, real-time, and sensitive gas analysis.

  10. Operating mode of high pressure straws with high spatial resolution

    CERN Document Server

    Davkov, K I; Peshekhonov, V D; Cholakov, V D

    2013-01-01

    The article presents results of studying the operating mode of thin-walled drift tubes (straws) at flushing it with a high-pressure gas mixture, which allowed obtaining extremely high spatial resolution for straw detectors. The results of studying the radiation ageing of straws operating in this mode are also described.

  11. Modeling Study of High Pressure and High Temperature Reservoir Fluids

    DEFF Research Database (Denmark)

    Varzandeh, Farhad

    to 250 °C and 2400 bar, in the deep petroleum reservoirs. Furthermore, many of these deep reservoirs are found offshore, including the North Sea and the Gulf of Mexico, making the development even more risky. On the other hand, development of these high pressure high temperature (HPHT) fields can...

  12. Pulse Radiolysis at High Temperatures and High Pressures

    DEFF Research Database (Denmark)

    Christensen, H.; Sehested, Knud

    1981-01-01

    A set-up enabling pulse radiolysis measurements at high temperatures (up to 320°C) and high pressures (up to 140 bar) has been constructed in collaboration between Risö National Laboratory and Studsvik Energiteknik. The cell has been used for experiments with aqueous solutions with the purpose...

  13. Dietary spermidine for lowering high blood pressure

    Science.gov (United States)

    Zimmermann, Andreas; Schroeder, Sabrina; Pendl, Tobias; Harger, Alexandra; Stekovic, Slaven; Schipke, Julia; Magnes, Christoph; Schmidt, Albrecht; Ruckenstuhl, Christoph; Dammbrueck, Christopher; Gross, Angelina S; Herbst, Viktoria; Carmona-Gutierrez, Didac; Pietrocola, Federico; Pieber, Thomas R; Sigrist, Stephan J; Linke, Wolfgang A; Mühlfeld, Christian; Sadoshima, Junichi; Dengjel, Joern; Kiechl, Stefan; Kroemer, Guido; Sedej, Simon; Madeo, Frank

    2017-01-01

    Loss of cardiac macroautophagy/autophagy impairs heart function, and evidence accumulates that an increased autophagic flux may protect against cardiovascular disease. We therefore tested the protective capacity of the natural autophagy inducer spermidine in animal models of aging and hypertension, which both represent major risk factors for the development of cardiovascular disease. Dietary spermidine elicits cardioprotective effects in aged mice through enhancing cardiac autophagy and mitophagy. In salt-sensitive rats, spermidine supplementation also delays the development of hypertensive heart disease, coinciding with reduced arterial blood pressure. The high blood pressure-lowering effect likely results from improved global arginine bioavailability and protection from hypertension-associated renal damage. The polyamine spermidine is naturally present in human diets, though to a varying amount depending on food type and preparation. In humans, high dietary spermidine intake correlates with reduced blood pressure and decreased risk of cardiovascular disease and related death. Altogether, spermidine represents a cardio- and vascular-protective autophagy inducer that can be readily integrated in common diets. PMID:28118075

  14. Runaway electrons preionized diffuse discharges at high pressure

    Science.gov (United States)

    Tarasenko, Victor F.; Lomaev, Mikhail I.; Sorokin, Dmitry A.

    2010-09-01

    Breakdown of the gaps with a non-uniform electric field filled with nitrogen and air as well as with other gases under high-voltage nanosecond pulses was investigated. It is shown that conditions of obtaining a diffuse discharge without a source of additional ionization are extended at the voltage pulse duration decreasing. A volume discharge is formed due to the gap pre-ionization by runaway electrons and X-ray quanta. At a negative polarity of the electrode with a small radius of curvature, a volume (diffuse) discharge formation is determined by pre-ionization with runaway electrons which are generated due to the electric field amplification near the cathode and in the gap. At a positive polarity of the electrode with a small radius of curvature, the X-ray radiation, generated at the runaway electrons braking at the anode and in the gap, is of great importance in a volume discharge formation. A runaway electrons preionized diffuse discharge (REP DD) has two characteristic stages. In the first stage, the ionization wave overlaps the gap during a fraction of a second. The discharge current is determined by the conductivity current in the dense plasma of the ionization wave and the displacement current in the remaining part of the gap. The second stage of the discharge can be related to the anomalous glow discharge with a high specific input power. During the second stage, the gap voltage decreases and the cathode spots formed as a result of explosive electron emission can participate in the electron emission from the cathode. At the increase of the voltage pulse duration and specific input power, the REP DD transforms into a spark discharge form. A REP DD is easily realized in various gases and at different pressures; see [1] and references in [1]. At pressure decrease was obtained the anode electrons beam current to rise (up to ~2 kA/cm2 in helium). At the REP DD, the anode is influenced by the plasma of a dense nanosecond discharge with the specific input power

  15. Innovative high pressure gas MEM's based neutron detector for ICF and active SNM detection.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Shawn Bryan; Derzon, Mark Steven; Renzi, Ronald F.; Chandler, Gordon Andrew

    2007-12-01

    An innovative helium3 high pressure gas detection system, made possible by utilizing Sandia's expertise in Micro-electrical Mechanical fluidic systems, is proposed which appears to have many beneficial performance characteristics with regards to making these neutron measurements in the high bremsstrahlung and electrical noise environments found in High Energy Density Physics experiments and especially on the very high noise environment generated on the fast pulsed power experiments performed here at Sandia. This same system may dramatically improve active WMD and contraband detection as well when employed with ultrafast (10-50 ns) pulsed neutron sources.

  16. High stored energy of metallic glasses induced by high pressure

    Science.gov (United States)

    Wang, C.; Yang, Z. Z.; Ma, T.; Sun, Y. T.; Yin, Y. Y.; Gong, Y.; Gu, L.; Wen, P.; Zhu, P. W.; Long, Y. W.; Yu, X. H.; Jin, C. Q.; Wang, W. H.; Bai, H. Y.

    2017-03-01

    Modulating energy states of metallic glasses (MGs) is significant in understanding the nature of glasses and controlling their properties. In this study, we show that high stored energy can be achieved and preserved in bulk MGs by high pressure (HP) annealing, which is a controllable method to continuously alter the energy states of MGs. Contrary to the decrease in enthalpy by conventional annealing at ambient pressure, high stored energy can occur and be enhanced by increasing both annealing temperature and pressure. By using double aberration corrected scanning transmission electron microscopy, it is revealed that the preserved high energy, which is attributed to the coupling effect of high pressure and high temperature, originates from the microstructural change that involves "negative flow units" with a higher atomic packing density compared to that of the elastic matrix of MGs. The results demonstrate that HP-annealing is an effective way to activate MGs into higher energy states, and it may assist in understanding the microstructural origin of high energy states in MGs.

  17. High pressure study of high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Souliou, Sofia-Michaela

    2014-09-29

    The current thesis studies experimentally the effect of high external pressure on high-T{sub c} superconductors. The structure and lattice dynamics of several members of the high-T{sub c} cuprate and Fe-based superconductors families were investigated by means of Raman spectroscopy and X-ray diffraction under well-controlled, hydrostatic high pressure and low temperature conditions. The lattice dynamics of the high-T{sub c} superconductor YBa{sub 2}Cu{sub 3}O{sub 6+x} have been investigated systematically by Raman spectroscopy as a function of doping (x = 0.95, 0.75, 0.60, 0.55, and 0.45) and external pressure. Under ambient pressure conditions, in addition to the Raman modes expected from group theory, we observe new Raman active phonons upon cooling the underdoped samples, at temperatures well above the superconducting transition temperature. The doping dependence and the onset temperatures of the new Raman features suggest that they are associated with the incommensurate charge density wave (CDW) state recently discovered in underdoped cuprates using synchrotron X-ray scattering techniques. Under high pressure conditions (from 2 to 12 GPa), our Raman measurements on highly ordered underdoped YBa{sub 2}Cu{sub 3}O{sub 6.55} samples do not show any of the new Raman phonons seen at ambient pressure. High pressure and low temperature Raman measurements have been performed on the underdoped superconductor YBa{sub 2}Cu{sub 4}O{sub 8}. A clear renormalization of some of the Raman phonons is seen below T{sub c} as a result of the changes in the phonon self-energy upon the opening of the superconducting gap, with the most prominent one being that of the B{sub 1g}-like buckling phonon mode. The amplitude of this renormalization strongly increases with pressure, resembling the effect of hole doping in YBa{sub 2}Cu{sub 3}O{sub 6+x}. At ∝ 10 GPa, the system undergoes a reversible pressure-induced structural phase transition to a non-centrosymmmetric structure (space group

  18. 高能量密度氘、氦的第一原理研究进展%High energy density deuterium and helium, ab initio studies

    Institute of Scientific and Technical Information of China (English)

    王聪; 贺贤土; 张平

    2012-01-01

    极端条件下氘、氦的研究对于凝聚态物理、等离子体物理、天体物理以及惯性约束聚变的研究具有重要意义.文章综述了近年来温稠密区、热稠密区以及低温高压区的最新研究进展,归纳了尚待解决的科学问题,从而为进一步的研究提供参考.%The thermal physical properties of materials such as deuterium and helium, under extreme conditions are of extreme interest in condensed matter physics, plasma physics, astrophysics, and inertial confinement fusion. A brief review is given of recent studies in the warm and hot dense regimes, and the high pressure, low temperature region. The challenges in this research area are also discussed.

  19. Menopause and High Blood Pressure: What's the Connection?

    Science.gov (United States)

    ... blood pressure (hypertension) Is there a connection between menopause and high blood pressure? Answers from Shannon K. ... Tommaso, M.D. Blood pressure generally increases after menopause. Some doctors think this increase suggests that hormonal ...

  20. A cryogenic axial-centrifugal compressor for superfluid helium refrigeration

    CERN Document Server

    Decker, L; Schustr, P; Vins, M; Brunovsky, I; Lebrun, P; Tavian, L

    1997-01-01

    CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.

  1. High-pressure-high-temperature treatment of natural diamonds

    CERN Document Server

    Royen, J V

    2002-01-01

    The results are reported of high-pressure-high-temperature (HPHT) treatment experiments on natural diamonds of different origins and with different impurity contents. The diamonds are annealed in a temperature range up to 2000 sup o C at stabilizing pressures up to 7 GPa. The evolution is studied of different defects in the diamond crystal lattice. The influence of substitutional nitrogen atoms, plastic deformation and the combination of these is discussed. Diamonds are characterized at room and liquid nitrogen temperature using UV-visible spectrophotometry, Fourier transform infrared spectrophotometry and photoluminescence spectrometry. The economic implications of diamond HPHT treatments are discussed.

  2. LHDAC setup for high temperature and high pressure studies

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Nishant N., E-mail: nnpatel@barc.gov.in; Meenakshi, S., E-mail: nnpatel@barc.gov.in; Sharma, Surinder M., E-mail: nnpatel@barc.gov.in [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai-400085 (India)

    2014-04-24

    A ytterbium fibre laser (λ = 1.07 μm) based laser heated diamond anvil cell (LHDAC) facility has been recently set up at HP and SRPD, BARC for simultaneous high temperature and high pressure investigation of material properties. Synthesis of GaN was carried out at pressure of ∼9 GPa and temperature of ∼1925 K in a Mao-Bell type diamond anvil cell (DAC) using the LHDAC facility. The retrieved sample has been characterized using our laboratory based micro Raman setup.

  3. 49 CFR 192.621 - Maximum allowable operating pressure: High-pressure distribution systems.

    Science.gov (United States)

    2010-10-01

    ... STANDARDS Operations § 192.621 Maximum allowable operating pressure: High-pressure distribution systems. (a) No person may operate a segment of a high pressure distribution system at a pressure that exceeds the... segment of a distribution system otherwise designed to operate at over 60 p.s.i. (414 kPa) gage,...

  4. High-pressure structural properties of tetramethylsilane

    Science.gov (United States)

    Zhen-Xing, Qin; Xiao-Jia, Chen

    2016-02-01

    High-pressure structural properties of tetramethylsilane are investigated by synchrotron powder x-ray diffraction at pressures up to 31.1 GPa and room temperature. A phase with the space group of Pnma is found to appear at 4.2 GPa. Upon compression, the compound transforms to two following phases: the phase with space groups of P21/c at 9.9 GPa and the phase with P2/m at 18.2 GPa successively via a transitional phase. The unique structural character of P21/c supports the phase stability of tetramethylsilane without possible decomposition upon heavy compression. The appearance of the P2/m phase suggests the possible realization of metallization for this material at higher pressure. Project supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project from Ministry of Education of China (Grant No. 708070), the Fundamental Research Funds for the Central Universities, South China University of Technology (Grant No. 2014ZZ0069), the National Natural Science Foundation of China (Grant No. 51502189), and the Doctoral Project of Taiyuan University of Science and Technology, China (Grant No. 20132010).

  5. High-pressure Raman study of Terephthalonitrile

    Science.gov (United States)

    Li, DongFei; Zhang, KeWei; Song, MingXing; Zhai, NaiCui; Sun, ChengLin; Li, HaiBo

    2017-02-01

    The in situ high-pressure Raman spectra of Terephthalonitrile (TPN) have been investigated from ambient to 12.6 GPa at room temperature. All the fundamental vibrational modes of TPN at ambient were assigned based on the first-principle calculations. A detailed Raman spectroscopy analysis revealed that TPN underwent a phase transition at 5.3 GPa. The frequencies of the TPN Raman peaks increase with increasing the pressure which can be attributed to the reduction in the interatomic distances and the escalation of effective force constants. The intensity of the C-C-C ring-out-plane deformation mode increases gradually as the frequency remains almost constant during the compression which can be explained by the existence of π-π interactions in TPN molecules. Additionally, the pressure-induced structural changes of TPN on the Fermi resonance between the C ≡ N out-of-plane vibration mode and the C - CN out-of-plane vibration mode have been analyzed.

  6. Recent progress in high-pressure studies on organic conductors

    Directory of Open Access Journals (Sweden)

    Syuma Yasuzuka and Keizo Murata

    2009-01-01

    Full Text Available Recent high-pressure studies of organic conductors and superconductors are reviewed. The discovery of the highest Tc superconductivity among organics under high pressure has triggered the further progress of the high-pressure research. Owing to this finding, various organic conductors with the strong electron correlation were investigated under high pressures. This review includes the pressure techniques using the cubic anvil apparatus, as well as high-pressure studies of the organic conductors up to 10 GPa showing extraordinary temperature and pressure dependent transport phenomena.

  7. High blood pressure in children and adolescents.

    Science.gov (United States)

    Riley, Margaret; Bluhm, Brian

    2012-04-01

    High blood pressure in children and adolescents is a growing health problem that is often overlooked by physicians. Normal blood pressure values for children and adolescents are based on age, sex, and height, and are available in standardized tables. Prehypertension is defined as a blood pressure in at least the 90th percentile, but less than the 95th percentile, for age, sex, and height, or a measurement of 120/80 mm Hg or greater. Hypertension is defined as blood pressure in the 95th percentile or greater. A secondary etiology of hypertension is much more likely in children than in adults, with renal parenchymal disease and renovascular disease being the most common. Overweight and obesity are strongly correlated with primary hypertension in children. A history and physical examination are needed for all children with newly diagnosed hypertension to help rule out underlying medical disorders. Children with hypertension should also be screened for other risk factors for cardiovascular disease, including diabetes mellitus and hyperlipidemia, and should be evaluated for target organ damage with a retinal examination and echocardiography. Hypertension in children is treated with lifestyle changes, including weight loss for those who are overweight or obese; a healthy, low-sodium diet; regular physical activity; and avoidance of tobacco and alcohol. Children with symptomatic hypertension, secondary hypertension, target organ damage, diabetes, or persistent hypertension despite nonpharmacologic measures should be treated with antihypertensive medications. Thiazide diuretics, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta blockers, and calcium channel blockers are safe, effective, and well tolerated in children.

  8. Conformable pressure vessel for high pressure gas storage

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Kevin L.; Johnson, Kenneth I.; Lavender, Curt A.; Newhouse, Norman L.; Yeggy, Brian C.

    2016-01-12

    A non-cylindrical pressure vessel storage tank is disclosed. The storage tank includes an internal structure. The internal structure is coupled to at least one wall of the storage tank. The internal structure shapes and internally supports the storage tank. The pressure vessel storage tank has a conformability of about 0.8 to about 1.0. The internal structure can be, but is not limited to, a Schwarz-P structure, an egg-crate shaped structure, or carbon fiber ligament structure.

  9. Theory of high pressure hydrogen, made simple

    CERN Document Server

    Magdau, Ioan B; Ackland, Graeme J

    2015-01-01

    Phase I of hydrogen has several peculiarities. Despite having a close-packed crystal structure, it is less dense than either the low temperature Phase II or the liquid phase. At high pressure, it transforms into either phase III or IV, depending on the temperature. Moreover, spectroscopy suggests that the quantum rotor behaviour disappears with pressurisation, without any apparent phase transition. Here we present a simple thermodynamic model for this behaviour based on packing atoms and molecules and discuss the thermodynamics of the phase boundaries. We also report first principles molecular dynamics calculations for a more detailed look at the same phase transitions.

  10. Discharge instabilities in high-pressure helium-fluorine laser gas mixtures

    NARCIS (Netherlands)

    Mathew, D.; Bastiaens, H.M.J.; Peters, P.J.M.; Boller, K.-J.

    2005-01-01

    Discharge instabilities in F2 based excimer gas lasers are investigated using a small-scale discharge system. After preionizing the gas volume, a fast rising voltage pulse initiates the discharge. The temporal development of the discharge is monitored via its fluorescence by an intensified CCD camer

  11. Discharge instabilities in high-pressure helium-fluorine laser gas mixtures

    NARCIS (Netherlands)

    Mathew, D.; Bastiaens, Hubertus M.J.; Peters, P.J.M.; Boller, Klaus J.

    2005-01-01

    Discharge instabilities in F2 based excimer gas lasers are investigated using a small-scale discharge system. After preionizing the gas volume, a fast rising voltage pulse initiates the discharge. The temporal development of the discharge is monitored via its fluorescence by an intensified CCD camer

  12. Discharge instabilities in high-pressure helium-fluorine laser gas mixtures

    NARCIS (Netherlands)

    Mathew, D.; Bastiaens, Hubertus M.J.; Peters, P.J.M.; Boller, Klaus J.

    2005-01-01

    Discharge instabilities in F2 based excimer gas lasers are investigated using a small-scale discharge system. After preionizing the gas volume, a fast rising voltage pulse initiates the discharge. The temporal development of the discharge is monitored via its fluorescence by an intensified CCD

  13. CDC Vital Signs: High Blood Pressure and Cholesterol

    Science.gov (United States)

    ... the MMWR Science Clips High Blood Pressure and Cholesterol Out of Control Recommend on Facebook Tweet Share ... cdc.gov/GISCVH2/ High Blood Pressure and High Cholesterol Among US Adults SOURCES: National Health and Nutrition ...

  14. High Blood Pressure and Children: What Parents Need to Know

    Science.gov (United States)

    ... Lung, and Blood Institute Alternate Language URL Español High Blood Pressure and Children: What Parents Need to Know Page Content Children can have high blood pressure. Did you know that children could have high ...

  15. Applicability of Henry's Law to helium solubility in olivine

    Science.gov (United States)

    Jackson, C.; Parman, S. W.; Kelley, S. P.; Cooper, R. F.

    2013-12-01

    Applicability of Henry's Law to helium solubility in olivine We have experimentally determined helium solubility in San Carlos olivine across a range of helium partial pressures (PHe) with the goal of quantifying how noble gases behave during partial melting of peridotite. Helium solubility in olivine correlates linearly with PHe between 55 and 1680 bar. This linear relationship suggests Henry's Law is applicable to helium dissolution into olivine up to 1680 bar PHe, providing a basis for extrapolation of solubility relationships determined at high PHe to natural systems. This is the first demonstration of Henry's Law for helium dissolution into olivine. Averaging all the data of the PHe series yields a Henry's coefficient of 3.8(×3.1)×10-12 mol g-1 bar-1. However, the population of Henry's coefficients shows a positive skew (skewness = 1.17), i.e. the data are skewed to higher values. This skew is reflected in the large standard deviation of the population of Henry's coefficients. Averaging the median values from each experiment yields a lower Henry's coefficient and standard deviation: 3.2(× 2.3)×10-12 mol g-1 bar-1. Combining the presently determined helium Henry's coefficient for olivine with previous determinations of helium Henry's coefficients for basaltic melts (e.g. 1) yields a partition coefficient of ~10-4. This value is similar to previous determinations obtained at higher PHe (2). The applicability of Henry's Law here suggests helium is incorporated onto relatively abundant sites within olivine that are not saturated by 1680 bar PHe or ~5×10-9 mol g-1. Large radius vacancies, i.e. oxygen vacancies, are energetically favorable sites for noble gas dissolution (3). However, oxygen vacancies are not abundant enough in San Carlos olivine to account for this solubility (e.g. 4), suggesting the 3x10-12 mol g-1 bar-1 Henry's coefficient is associated with interstitial dissolution of helium. Helium was dissolved into olivine using an externally heated

  16. Crystal structure and density of helium to 232 kbar

    Science.gov (United States)

    Mao, H. K.; Wu, Y.; Jephcoat, A. P.; Hemley, R. J.; Bell, P. M.; Bassett, W. A.

    1988-01-01

    The properties of helium and hydrogen at high pressure are topics of great interest to the understanding of planetary interiors. These materials constitute 95 percent of the entire solar system. A technique was presented for the measurement of X-ray diffraction from single-crystals of low-Z condenses gases in a diamond-anvil cell at high pressure. The first such single-crystal X-ray diffraction measurements on solid hydrogen to 26.5 GPa were presented. The application of this technique to the problem of the crystal structure, equation of state, and phase diagram of solid helium is reported. Crucial for X-ray diffraction studies of these materials is the use of a synchrotron radiation source which provides high brillance, narrow collimation of the incident and diffracted X-ray beams to reduce the background noise, and energy-dispersive diffraction techniques with polychromatic (white) radiation, which provides high detection efficiency.

  17. High Resolution Infrared Spectroscopy of Propargyl Alcohol-Water Complex Embedded in Helium Nanodroplets

    Science.gov (United States)

    Mani, Devendra; Pal, Nitish; Kaufmann, Matin; Schwaab, Gerhard; Havenith, Martina

    2016-06-01

    Propargyl alcohol (hereafter abbreviated as PA) is a molecule of astrophysical interest and has been probed extensively using microwave spectroscopy.1,2 It is a multifunctional molecule and offers multiple sites for hydrogen bonding interactions. Therefore, it has also attracted the attention of groups interested in weak intermolecular interactions. Recently, the Ar…PA complex3 and PA-dimer4 have been studied using microwave spectroscopy. More recently, there have been matrix-isolation infrared spectroscopic studies on PA-water5 and PA-acetylene6 complexes. In the present work, clusters of PA and water were formed in the helium nanodroplets and probed using a combination of infrared spectroscopy and mass spectrometry. Using ab-initio quantum mechanical calculations, PA-water clusters were optimised and five minimum structures were found on the potential energy hypersurface, which were used as a guidance to the experiments. We used D2O for the experiments since our laser sources at Bochum do not cover the IR spectral region of H2O. IR spectra of PA-D2O complex were recorded in the region of symmetric and antisymmetric stretches of the bound D2O. Multiple signals were found in these regions which were dependent on the concentration of PA as well as D2O. Using pickup curves most of these signals could be assigned to 1:1 PA:D2O clusters. The ab-initio calculations helped in a definitive assignment of the spectra to the different conformers of PA-D2O complex. The details will be presented in the talk. References: 1. E. Hirota, J. Mol. Spec. 26, 335 (1968). 2. J.C. Pearson and B.J. Drouin, J. Mol. Spectrosc. 234, 149 (2005). 3. D. Mani and E. Arunan, ChemPhysChem 14, 754 (2013). 4. D. Mani and E. Arunan, J. Chem. Phys. 141, 164311 (2014). 5. J. Saini, K.S. Vishwanathan, J. Mol. Struct. 1118, 147 (2016). 6. K. Sundararajan et al., J. Mol. Struct. 1121, 26 (2016).

  18. Method transfer from high-pressure liquid chromatography to ultra-high-pressure liquid chromatography. II. Temperature and pressure effects.

    Science.gov (United States)

    Åsberg, Dennis; Samuelsson, Jörgen; Leśko, Marek; Cavazzini, Alberto; Kaczmarski, Krzysztof; Fornstedt, Torgny

    2015-07-03

    The importance of the generated temperature and pressure gradients in ultra-high-pressure liquid chromatography (UHPLC) are investigated and compared to high-pressure liquid chromatography (HPLC). The drug Omeprazole, together with three other model compounds (with different chemical characteristics, namely uncharged, positively and negatively charged) were used. Calculations of the complete temperature profile in the column at UHPLC conditions showed, in our experiments, a temperature difference between the inlet and outlet of 16 °C and a difference of 2 °C between the column center and the wall. Through van't Hoff plots, this information was used to single out the decrease in retention factor (k) solely due to the temperature gradient. The uncharged solute was least affected by temperature with a decrease in k of about 5% while for charged solutes the effect was more pronounced, with k decreases up to 14%. A pressure increase of 500 bar gave roughly 5% increase in k for the uncharged solute, while omeprazole and the other two charged solutes gave about 25, 20 and 15% increases in k, respectively. The stochastic model of chromatography was applied to estimate the dependence of the average number of adsorption/desorption events (n) and the average time spent by a molecule in the stationary phase (τs) on temperature and pressure on peak shape for the tailing, basic solute. Increasing the temperature yielded an increase in n and decrease in τs which resulted in less skew at high temperatures. With increasing pressure, the stochastic modeling gave interesting results for the basic solute showing that the skew of the peak increased with pressure. The conclusion is that pressure effects are more pronounced for both retention and peak shape than the temperature effects for the polar or charged compounds in our study.

  19. High blood pressure and visual sensitivity

    Science.gov (United States)

    Eisner, Alvin; Samples, John R.

    2003-09-01

    The study had two main purposes: (1) to determine whether the foveal visual sensitivities of people treated for high blood pressure (vascular hypertension) differ from the sensitivities of people who have not been diagnosed with high blood pressure and (2) to understand how visual adaptation is related to standard measures of systemic cardiovascular function. Two groups of middle-aged subjects-hypertensive and normotensive-were examined with a series of test/background stimulus combinations. All subjects met rigorous inclusion criteria for excellent ocular health. Although the visual sensitivities of the two subject groups overlapped extensively, the age-related rate of sensitivity loss was, for some measures, greater for the hypertensive subjects, possibly because of adaptation differences between the two groups. Overall, the degree of steady-state sensitivity loss resulting from an increase of background illuminance (for 580-nm backgrounds) was slightly less for the hypertensive subjects. Among normotensive subjects, the ability of a bright (3.8-log-td), long-wavelength (640-nm) adapting background to selectively suppress the flicker response of long-wavelength-sensitive (LWS) cones was related inversely to the ratio of mean arterial blood pressure to heart rate. The degree of selective suppression was also related to heart rate alone, and there was evidence that short-term changes of cardiovascular response were important. The results suggest that (1) vascular hypertension, or possibly its treatment, subtly affects visual function even in the absence of eye disease and (2) changes in blood flow affect retinal light-adaptation processes involved in the selective suppression of the flicker response from LWS cones caused by bright, long-wavelength backgrounds.

  20. High-pressure coal fuel processor development

    Energy Technology Data Exchange (ETDEWEB)

    Greenhalgh, M.L.

    1992-11-01

    The objective of Subtask 1.1 Engine Feasibility was to conduct research needed to establish the technical feasibility of ignition and stable combustion of directly injected, 3,000 psi, low-Btu gas with glow plug ignition assist at diesel engine compression ratios. This objective was accomplished by designing, fabricating, testing and analyzing the combustion performance of synthesized low-Btu coal gas in a single-cylinder test engine combustion rig located at the Caterpillar Technical Center engine lab in Mossville, Illinois. The objective of Subtask 1.2 Fuel Processor Feasibility was to conduct research needed to establish the technical feasibility of air-blown, fixed-bed, high-pressure coal fuel processing at up to 3,000 psi operating pressure, incorporating in-bed sulfur and particulate capture. This objective was accomplished by designing, fabricating, testing and analyzing the performance of bench-scale processors located at Coal Technology Corporation (subcontractor) facilities in Bristol, Virginia. These two subtasks were carried out at widely separated locations and will be discussed in separate sections of this report. They were, however, independent in that the composition of the synthetic coal gas used to fuel the combustion rig was adjusted to reflect the range of exit gas compositions being produced on the fuel processor rig. Two major conclusions resulted from this task. First, direct injected, ignition assisted Diesel cycle engine combustion systems can be suitably modified to efficiently utilize these low-Btu gas fuels. Second, high pressure gasification of selected run-of-the-mine coals in batch-loaded fuel processors is feasible. These two findings, taken together, significantly reduce the perceived technical risks associated with the further development of the proposed coal gas fueled Diesel cycle power plant concept.

  1. High Pressure Hydrogen from First Principles

    Science.gov (United States)

    Morales, M. A.

    2014-12-01

    Typical approximations employed in first-principles simulations of high-pressure hydrogen involve the neglect of nuclear quantum effects (NQE) and the approximate treatment of electronic exchange and correlation, typically through a density functional theory (DFT) formulation. In this talk I'll present a detailed analysis of the influence of these approximations on the phase diagram of high-pressure hydrogen, with the goal of identifying the predictive capabilities of current methods and, at the same time, making accurate predictions in this important regime. We use a path integral formulation combined with density functional theory, which allows us to incorporate NQEs in a direct and controllable way. In addition, we use state-of-the-art quantum Monte Carlo calculations to benchmark the accuracy of more approximate mean-field electronic structure calculations based on DFT, and we use GW and hybrid DFT to calculate the optical properties of the solid and liquid phases near metallization. We present accurate predictions of the metal-insulator transition on the solid, including structural and optical properties of the molecular phase. This work was supported by the U.S. Department of Energy at the Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and by LDRD Grant No. 13-LW-004.

  2. High pressure-resistant nonincendive emulsion explosive

    Science.gov (United States)

    Ruhe, Thomas C.; Rao, Pilaka P.

    1994-01-01

    An improved emulsion explosive composition including hollow microspheres/bulking agents having high density and high strength. The hollow microspheres/bulking agents have true particle densities of about 0.2 grams per cubic centimeter or greater and include glass, siliceous, ceramic and synthetic resin microspheres, expanded minerals, and mixtures thereof. The preferred weight percentage of hollow microspheres/bulking agents in the composition ranges from 3.0 to 10.0 A chlorinated paraffin oil, also present in the improved emulsion explosive composition, imparts a higher film strength to the oil phase in the emulsion. The emulsion is rendered nonincendive by the production of sodium chloride in situ via the decomposition of sodium nitrate, a chlorinated paraffin oil, and sodium perchlorate. The air-gap sensitivity is improved by the in situ formation of monomethylamine perchlorate from dissolved monomethylamine nitrate and sodium perchlorate. The emulsion explosive composition can withstand static pressures to 139 bars and dynamic pressure loads on the order of 567 bars.

  3. Stable magnesium peroxide at high pressure.

    Science.gov (United States)

    Lobanov, Sergey S; Zhu, Qiang; Holtgrewe, Nicholas; Prescher, Clemens; Prakapenka, Vitali B; Oganov, Artem R; Goncharov, Alexander F

    2015-09-01

    Rocky planets are thought to comprise compounds of Mg and O as these are among the most abundant elements, but knowledge of their stable phases may be incomplete. MgO is known to be remarkably stable to very high pressure and chemically inert under reduced condition of the Earth's lower mantle. However, in exoplanets oxygen may be a more abundant constituent. Here, using synchrotron x-ray diffraction in laser-heated diamond anvil cells, we show that MgO and oxygen react at pressures above 96 GPa and T = 2150 K with the formation of I4/mcm MgO2. Raman spectroscopy detects the presence of a peroxide ion (O2(2-)) in the synthesized material as well as in the recovered specimen. Likewise, energy-dispersive x-ray spectroscopy confirms that the recovered sample has higher oxygen content than pure MgO. Our finding suggests that MgO2 may be present together or instead of MgO in rocky mantles and rocky planetary cores under highly oxidized conditions.

  4. Stable magnesium peroxide at high pressure

    Science.gov (United States)

    Lobanov, Sergey S.; Zhu, Qiang; Holtgrewe, Nicholas; Prescher, Clemens; Prakapenka, Vitali B.; Oganov, Artem R.; Goncharov, Alexander F.

    2015-09-01

    Rocky planets are thought to comprise compounds of Mg and O as these are among the most abundant elements, but knowledge of their stable phases may be incomplete. MgO is known to be remarkably stable to very high pressure and chemically inert under reduced condition of the Earth’s lower mantle. However, in exoplanets oxygen may be a more abundant constituent. Here, using synchrotron x-ray diffraction in laser-heated diamond anvil cells, we show that MgO and oxygen react at pressures above 96 GPa and T = 2150 K with the formation of I4/mcm MgO2. Raman spectroscopy detects the presence of a peroxide ion (O22-) in the synthesized material as well as in the recovered specimen. Likewise, energy-dispersive x-ray spectroscopy confirms that the recovered sample has higher oxygen content than pure MgO. Our finding suggests that MgO2 may be present together or instead of MgO in rocky mantles and rocky planetary cores under highly oxidized conditions.

  5. High-pressure structures of yttrium hydrides

    Science.gov (United States)

    Liu, Lu-Lu; Sun, Hui-Juan; Wang, C. Z.; Lu, Wen-Cai

    2017-08-01

    In this work, the crystal structures of YH3 and YH4 at high pressure (100-250 GPa) have been explored using a genetic algorithm combined with first-principles calculations. New structures of YH3 with space group symmetries of P21/m and I4/mmm were predicted. The electronic structures and the phonon dispersion properties of various YH3 and YH4 structures at different temperatures and pressures were investigated. Among YH3 phases, the P21/m structure of YH3 was found to have a relatively high superconducting transformation temperature T c of 19 K at 120 GPa, which is reduced to 9 K at 200 GPa. Other YH3 structures have much lower T cs. Compared with YH3, the T c of the YH4 compound is much higher, i.e. 94 K at 120 GPa and 55 K at 200 GPa.

  6. High Speed Switching Micoplasma in High Pressure Gases

    Science.gov (United States)

    Wakim, Dani; Staack, David

    2012-10-01

    Micro-plasma discharges with switching times approaching 1 ns are studied at pressures from 1 to 16 atm. Applications of these devices are robust high speed switching transistors able to withstand electric interference, high temperatures and harsh environments. Measured discharge conditions at 250 psia in Nitrogen are: gas temperature 2900 K, discharge diameter ˜7 μm and electron density ˜10^17 cm-3. High speed switching is achieved by taking advantage of rapid dynamics of instabilities at high pressure and high electron density. The capacitance and inductance of the circuit also significantly affect transients. Tradeoffs are observed in switching times. By reducing capacitances from 10 pF to ˜1pF attainment of steady state conditions can be reduced from 1 us to ˜ 20 ns. However current rise times increase from 1 ns at high capacitance to 20 ns at low capacitance. A decrease in switching time with increased pressure is also observed. Also investigated are configurations with a third electrode acting as a gate or trigger and various high temperature (>2000K) materials such as platinum rhodium alloys and ceria stabilized zirconia ceramics for device fabrication.

  7. Synthesis of sodium polyhydrides at high pressures.

    Science.gov (United States)

    Struzhkin, Viktor V; Kim, Duck Young; Stavrou, Elissaios; Muramatsu, Takaki; Mao, Ho-Kwang; Pickard, Chris J; Needs, Richard J; Prakapenka, Vitali B; Goncharov, Alexander F

    2016-01-01

    The only known compound of sodium and hydrogen is archetypal ionic NaH. Application of high pressure is known to promote states with higher atomic coordination, but extensive searches for polyhydrides with unusual stoichiometry have had only limited success in spite of several theoretical predictions. Here we report the first observation of the formation of polyhydrides of Na (NaH3 and NaH7) above 40 GPa and 2,000 K. We combine synchrotron X-ray diffraction and Raman spectroscopy in a laser-heated diamond anvil cell and theoretical random structure searching, which both agree on the stable structures and compositions. Our results support the formation of multicenter bonding in a material with unusual stoichiometry. These results are applicable to the design of new energetic solids and high-temperature superconductors based on hydrogen-rich materials.

  8. Synthesis of sodium polyhydrides at high pressures

    Science.gov (United States)

    Struzhkin, Viktor V.; Kim, Duck Young; Stavrou, Elissaios; Muramatsu, Takaki; Mao, Ho-Kwang; Pickard, Chris J.; Needs, Richard J.; Prakapenka, Vitali B.; Goncharov, Alexander F.

    2016-07-01

    The only known compound of sodium and hydrogen is archetypal ionic NaH. Application of high pressure is known to promote states with higher atomic coordination, but extensive searches for polyhydrides with unusual stoichiometry have had only limited success in spite of several theoretical predictions. Here we report the first observation of the formation of polyhydrides of Na (NaH3 and NaH7) above 40 GPa and 2,000 K. We combine synchrotron X-ray diffraction and Raman spectroscopy in a laser-heated diamond anvil cell and theoretical random structure searching, which both agree on the stable structures and compositions. Our results support the formation of multicenter bonding in a material with unusual stoichiometry. These results are applicable to the design of new energetic solids and high-temperature superconductors based on hydrogen-rich materials.

  9. Food processing by high hydrostatic pressure.

    Science.gov (United States)

    Yamamoto, Kazutaka

    2017-04-01

    High hydrostatic pressure (HHP) process, as a nonthermal process, can be used to inactivate microbes while minimizing chemical reactions in food. In this regard, a HHP level of 100 MPa (986.9 atm/1019.7 kgf/cm(2)) and more is applied to food. Conventional thermal process damages food components relating color, flavor, and nutrition via enhanced chemical reactions. However, HHP process minimizes the damages and inactivates microbes toward processing high quality safe foods. The first commercial HHP-processed foods were launched in 1990 as fruit products such as jams, and then some other products have been commercialized: retort rice products (enhanced water impregnation), cooked hams and sausages (shelf life extension), soy sauce with minimized salt (short-time fermentation owing to enhanced enzymatic reactions), and beverages (shelf life extension). The characteristics of HHP food processing are reviewed from viewpoints of nonthermal process, history, research and development, physical and biochemical changes, and processing equipment.

  10. In situ gas analysis for high pressure applications using property measurements.

    Science.gov (United States)

    Moeller, J; Span, R; Fieback, T

    2013-10-01

    As the production, distribution, and storage of renewable energy based fuels usually are performed under high pressures and as there is a lack of in situ high pressure gas analysis instruments on the market, the aim of this work was to develop a method for in situ high pressure gas analysis of biogas and hydrogen containing gas mixtures. The analysis is based on in situ measurements of optical, thermo physical, and electromagnetic properties in gas mixtures with newly developed high pressure sensors. This article depicts the calculation of compositions from the measured properties, which is carried out iteratively by using highly accurate equations of state for gas mixtures. The validation of the method consisted of the generation and measurement of several mixtures, of which three are presented herein: a first mixture of 64.9 mol. % methane, 17.1 mol. % carbon dioxide, 9 mol. % helium, and 9 mol. % ethane at 323 K and 423 K in a pressure range from 2.5 MPa to 17 MPa; a second mixture of 93.0 mol. % methane, 4.0 mol. % propane, 2.0 mol. % carbon dioxide, and 1.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 1.2 MPa to 3 MPa; and a third mixture of 64.9 mol. % methane, 30.1 mol. % carbon dioxide, and 5.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 2.5 MPa to 4 MPa. The analysis of the tested gas mixtures showed that with measured density, velocity of sound, and relative permittivity the composition can be determined with deviations below 1.9 mol. %, in most cases even below 1 mol. %. Comparing the calculated compositions with the generated gas mixture, the deviations were in the range of the combined uncertainty of measurement and property models.

  11. Rheological assessment of nanofluids at high pressure high temperature

    Science.gov (United States)

    Kanjirakat, Anoop; Sadr, Reza

    2013-11-01

    High pressure high temperature (HPHT) fluids are commonly encountered in industry, for example in cooling and/or lubrications applications. Nanofluids, engineered suspensions of nano-sized particles dispersed in a base fluid, have shown prospective as industrial cooling fluids due to their enhanced rheological and heat transfer properties. Nanofluids can be potentially utilized in oil industry for drilling fluids and for high pressure water jet cooling/lubrication in machining. In present work rheological characteristics of oil based nanofluids are investigated at HPHT condition. Nanofluids used in this study are prepared by dispersing commercially available SiO2 nanoparticles (~20 nm) in a mineral oil. The basefluid and nanofluids with two concentrations, namely 1%, and 2%, by volume, are considered in this investigation. The rheological characteristics of base fluid and the nanofluids are measured using an industrial HPHT viscometer. Viscosity values of the nanofluids are measured at pressures of 100 kPa to 42 MPa and temperatures ranging from 25°C to 140°C. The viscosity values of both nanofluids as well as basefluid are observed to have increased with the increase in pressure. Funded by Qatar National Research Fund (NPRP 08-574-2-239).

  12. Determination of the proton-to-helium ratio in cosmic rays at ultra-high energies from the tail of the $X_{\\rm max}$ distribution

    CERN Document Server

    Yushkov, Alexey; Werner, Marek; Krieg, Julius

    2016-01-01

    We present a method to determine the proton-to-helium ratio in cosmic rays at ultra-high energies. It makes use of the exponential slope, $\\Lambda$, of the tail of the $X_{\\rm max}$ distribution measured by an air shower experiment. The method is quite robust with respect to uncertainties from modeling hadronic interactions and to systematic errors on $X_{\\rm max}$ and energy, and to the possible presence of primary nuclei heavier than helium. Obtaining the proton-to-helium ratio with air shower experiments would be a remarkable achievement. To quantify the applicability of a particular mass-sensitive variable for mass composition analysis despite hadronic uncertainties we introduce as a metric the `analysis indicator' and find an improved performance of the $\\Lambda$ method compared to other variables currently used in the literature. The fraction of events in the tail of the $X_{\\rm max}$ distribution can provide additional information on the presence of nuclei heavier than helium in the primary beam.

  13. The high-pressure behavior of bloedite

    DEFF Research Database (Denmark)

    Comodi, Paola; Nazzareni, Sabrina; Balic Zunic, Tonci

    2014-01-01

    High-pressure single-crystal synchrotron X‑ray diffraction was carried out on a single crystal of bloedite [Na2Mg(SO4)24H2O] compressed in a diamond-anvil cell. The volume-pressure data, collected up to 11.2 GPa, were fitted by a second- and a third-order Birch-Murnaghan equation of state (EOS......), yielding V0 = 495.6(7) Å3 with K0 = 39.9(6) GPa, and V0 = 496.9(7) Å3, with K0 = 36(1) GPa and K′ = 5.1 (4) GPa-1, respectively. The axial moduli were calculated using a Birch-Murnaghan EOS truncated at the second order, fixing K′ equal to 4, for a and b axes and a third-order Birch-Murnaghan EOS for c...... axis. The results were a0 = 11.08(1) and K0 = 56(3) GPa, b0 = 8.20(2) and K0 = 43(3) GPa, and c0 = 5.528(5), K0 = 40(2) GPa, K′ = 1.7(3) GPa-1. The values of the compressibility for a, b, and c axes are ba = 0.0060(3) GPa-1, bb = 0.0078(5) GPa-1, bc = 0.0083(4) GPa-1 with an anisotropic ratio of ba...

  14. [High blood pressure and physical exercise].

    Science.gov (United States)

    Sosner, P; Gremeaux, V; Bosquet, L; Herpin, D

    2014-06-01

    High blood pressure is a frequent pathology with many cardiovascular complications. As highlighted in guidelines, the therapeutic management of hypertension relies on non-pharmacological measures, which are diet and regular physical activity, but both patients and physicians are reluctant to physical activity prescription. To acquire the conviction that physical activity is beneficial, necessary and possible, we can take into account some fundamental and clinical studies, as well as the feedback of our clinical practice. Physical inactivity is a major risk factor for cardiovascular morbidity and mortality, and hypertension contributes to increase this risk. Conversely, regular practice of physical activity decreases very significantly the risk by up to 60%. The acute blood pressure changes during exercise and post-exercise hypotension differs according to the dynamic component (endurance or aerobic and/or strength exercises), but the repetition of the sessions leads to the chronic hypotensive benefit of physical activity. Moreover, physical activity prescription must take into account the assessment of global cardiovascular risk, the control of the hypertension, and the opportunities and desires of the patient in order to promote good adherence and beneficial lifestyle change. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  15. Engineering Model of High Pressure Moist Air

    Directory of Open Access Journals (Sweden)

    Hyhlík Tomáš

    2017-01-01

    Full Text Available The article deals with the moist air equation of state. There are equations of state discussed in the article, i.e. the model of an ideal mixture of ideal gases, the model of an ideal mixture of real gases and the model based on the virial equation of state. The evaluation of sound speed based on the ideal mixture concept is mentioned. The sound speed calculated by the model of an ideal mixture of ideal gases is compared with the sound speed calculated by using the model based on the concept of an ideal mixture of real gases. The comparison of enthalpy end entropy based on the model of an ideal mixture of ideal gases and the model of an ideal mixture of real gases is performed. It is shown that the model of an ideal mixture of real gases deviates from the model of an ideal mixture of ideal gases only in the case of high pressure. An impossibility of the definition of partial pressure in the mixture of real gases is discussed, where the virial equation of state is used.

  16. High pressure gas flow, storage, and displacement in fractured rock-Experimental setup development and application.

    Science.gov (United States)

    Hadi Mosleh, M; Turner, M; Sedighi, M; Vardon, P J

    2017-01-01

    This paper presents the design, development, and application of a laboratory setup for the experimental investigations of gas flow and reactions in a fractured rock. The laboratory facility comprises (i) a high pressure manometric sorption apparatus, where equilibrium and kinetic phenomena of adsorption and desorption can be examined, (ii) a high pressure triaxial core flooding system where the chemical reactive transport properties or processes can be explored, and (iii) an ancillary system including pure and mixed gas supply and analysis units. Underground conditions, in terms of pore pressure, confining pressure, and temperature, can be replicated using the triaxial core flooding system developed for depths up to 2 km. Core flooding experiments can be conducted under a range of gas injection pressures up to 20 MPa and temperatures up to 338 K. Details of the design considerations and the specification for the critical measuring instruments are described. The newly developed laboratory facility has been applied to study the adsorption of N2, CH4, and CO2 relevant to applications in carbon sequestration in coal and enhanced coalbed methane recovery. Under a wide range of pressures, the flow of helium in a core sample was studied and the evolution of absolute permeability at different effective stress conditions has been investigated. A comprehensive set of high resolution data has been produced on anthracite coal samples from the South Wales coalfield, using the developed apparatus. The results of the applications provide improved insight into the high pressure flow and reaction of various gas species in the coal samples from the South Wales coalfield.

  17. High pressure gas flow, storage, and displacement in fractured rock—Experimental setup development and application

    Science.gov (United States)

    Hadi Mosleh, M.; Turner, M.; Sedighi, M.; Vardon, P. J.

    2017-01-01

    This paper presents the design, development, and application of a laboratory setup for the experimental investigations of gas flow and reactions in a fractured rock. The laboratory facility comprises (i) a high pressure manometric sorption apparatus, where equilibrium and kinetic phenomena of adsorption and desorption can be examined, (ii) a high pressure triaxial core flooding system where the chemical reactive transport properties or processes can be explored, and (iii) an ancillary system including pure and mixed gas supply and analysis units. Underground conditions, in terms of pore pressure, confining pressure, and temperature, can be replicated using the triaxial core flooding system developed for depths up to 2 km. Core flooding experiments can be conducted under a range of gas injection pressures up to 20 MPa and temperatures up to 338 K. Details of the design considerations and the specification for the critical measuring instruments are described. The newly developed laboratory facility has been applied to study the adsorption of N2, CH4, and CO2 relevant to applications in carbon sequestration in coal and enhanced coalbed methane recovery. Under a wide range of pressures, the flow of helium in a core sample was studied and the evolution of absolute permeability at different effective stress conditions has been investigated. A comprehensive set of high resolution data has been produced on anthracite coal samples from the South Wales coalfield, using the developed apparatus. The results of the applications provide improved insight into the high pressure flow and reaction of various gas species in the coal samples from the South Wales coalfield.

  18. High pressure fiber optic sensor system

    Science.gov (United States)

    Guida, Renato; Xia, Hua; Lee, Boon K; Dekate, Sachin N

    2013-11-26

    The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

  19. High resolution electron microscopy of Ag-clusters in crystalline and non-crystalline morphologies grown inside superfluid helium nanodroplets

    Energy Technology Data Exchange (ETDEWEB)

    Volk, Alexander; Thaler, Philipp; Koch, Markus; Ernst, Wolfgang E. [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria); Fisslthaler, Evelin [Graz Centre for Electron Microscopy, Steyrergasse 17, A-8010 Graz (Austria); Grogger, Werner [Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, A-8010 Graz (Austria)

    2013-06-07

    We present a first investigation of structural properties of Ag clusters with a diameter of up to 5.5 nm grown inside superfluid helium nanodroplets (He{sub N}) and deposited on an amorphous C surface. With high resolution transmission electron microscope images we are able to show that in addition to the crystalline face centered cubic (fcc) structure, noncrystalline icosahedral (Ih), and decahedral (Dh) morphologies are grown. Relative abundances (56% fcc, 31% Dh, and 13% Ih) as well as the size distribution of each morphology (mean diameters d{sub fcc}=2.62(5) nm, d{sub Dh}=3.34(7) nm, and d{sub Ih}=3.93(2) nm) do not reflect the situation expected from pure energetic considerations, where small Ihs should be followed by medium sized Dhs and large fccs. Instead, kinetic factors seem to play an important role in the formation of these structures, as it appears to be the case for clusters formed by inert gas aggregation. Considering the low temperatures (0.37 K) and extremely high cooling rates, we discuss basic ideas that might lead to a qualitative picture of the cluster formation process inside He{sub N}.

  20. Sleep Deprivation: A Cause of High Blood Pressure?

    Science.gov (United States)

    ... High blood pressure (hypertension) Is it true that sleep deprivation can cause high blood pressure? Answers from Sheldon ... Cirelli C, et al. Definition and consequences of sleep deprivation. http://www.uptodate.com/home. Accessed March 24, ...

  1. High Blood Pressure, Afib and Your Risk of Stroke

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More High Blood Pressure, Afib and Your Risk of Stroke Updated:Sep ... have a stroke for the first time have high blood pressure . And an irregular atrial heart rhythm — a condition ...

  2. High blood pressure - what to ask your doctor

    Science.gov (United States)

    What to ask your doctor about high blood pressure; Hypertension - what to ask your doctor ... problems? What medicines am I taking to treat high blood pressure? Do they have any side effects? What should ...

  3. A Nutritional Strategy for the Treatment of High Blood Pressure.

    Science.gov (United States)

    Podell, Richard N.

    1984-01-01

    Some physicians wonder if high blood pressure can be controlled without the use of drugs and their potential side effects. Current findings concerning nutrition and high blood pressure are presented. (RM)

  4. High Blood Pressure Rates Have Doubled Worldwide Since 1975

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_162069.html High Blood Pressure Rates Have Doubled Worldwide Since 1975 Most of ... News) -- The number of people worldwide with high blood pressure has nearly doubled over the past 40 years, ...

  5. Novel High Pressure Pump-on-a-Chip Technology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — HJ Science & Technology, Inc. proposes to develop a novel high pressure "pump-on-a-chip" (HPPOC) technology capable of generating high pressure and flow rate on...

  6. DNS of High Pressure Supercritical Combustion

    Science.gov (United States)

    Chong, Shao Teng; Raman, Venkatramanan

    2016-11-01

    Supercritical flows have always been important to rocket motors, and more recently to aircraft engines and stationary gas turbines. The purpose of the present study is to understand effects of differential diffusion on reacting scalars using supercritical isotropic turbulence. Focus is on fuel and oxidant reacting in the transcritical region where density, heat capacity and transport properties are highly sensitive to variations in temperature and pressure. Reynolds and Damkohler number vary as a result and although it is common to neglect differential diffusion effects if Re is sufficiently large, this large variation in temperature with heat release can accentuate molecular transport differences. Direct numerical simulations (DNS) for one step chemistry reaction between fuel and oxidizer are used to examine the differential diffusion effects. A key issue investigated in this paper is if the flamelet progress variable approach, where the Lewis number is usually assumed to be unity and constant for all species, can be accurately applied to simulate supercritical combustion.

  7. High-pressure structures of methane hydrate

    CERN Document Server

    Hirai, H; Fujihisa, H; Sakashita, M; Katoh, E; Aoki, K; Yamamoto, Y; Nagashima, K; Yagi, T

    2002-01-01

    Three high-pressure structures of methane hydrate, a hexagonal structure (str. A) and two orthorhombic structures (str. B and str. C), were found by in situ x-ray diffractometry and Raman spectroscopy. The well-known structure I (str. I) decomposed into str. A and fluid at 0.8 GPa. Str. A transformed into str. B at 1.6 GPa, and str. B further transformed into str. C at 2.1 GPa which survived above 7.8 GPa. The fluid solidified as ice VI at 1.4 GPa, and the ice VI transformed to ice VII at 2.1 GPa. The bulk moduli, K sub 0 , for str. I, str. A, and str. C were calculated to be 7.4, 9.8, and 25.0 GPa, respectively.

  8. Urea and deuterium mixtures at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, M., E-mail: m.donnelly-2@sms.ed.ac.uk; Husband, R. J.; Frantzana, A. D.; Loveday, J. S. [Centre for Science at Extreme Conditions and School of Physics and Astronomy, The University of Edinburgh, Erskine Williamson Building, Peter Guthrie Tait Road, The King’s Buildings, Edinburgh EH9 3FD (United Kingdom); Bull, C. L. [ISIS, Rutherford Appleton Laboratory, Oxford Harwell, Didcot OX11 0QX (United Kingdom); Klotz, S. [IMPMC, CNRS UMR 7590, Université P and M Curie, 4 Place Jussieu, 75252 Paris (France)

    2015-03-28

    Urea, like many network forming compounds, has long been known to form inclusion (guest-host) compounds. Unlike other network formers like water, urea is not known to form such inclusion compounds with simple molecules like hydrogen. Such compounds if they existed would be of interest both for the fundamental insight they provide into molecular bonding and as potential gas storage systems. Urea has been proposed as a potential hydrogen storage material [T. A. Strobel et al., Chem. Phys. Lett. 478, 97 (2009)]. Here, we report the results of high-pressure neutron diffraction studies of urea and D{sub 2} mixtures that indicate no inclusion compound forms up to 3.7 GPa.

  9. Simulating a high pressure die casting

    Energy Technology Data Exchange (ETDEWEB)

    Goldak, J.; Zhou, J.; Downey, D.; Aldea, V.; Li, G.; Mocanita, M. [Carleton Univ., Ottawa, Ontario (Canada)

    2000-07-01

    High pressure die casting is simulated for parts with complex geometry such as a large automotive transmission case. The closed die is filled in approximately 40 ms, the casting cools in the closed die for approximately 40s, to open the die, eject the casting and spray the die cavity surface requires another 40s. This 3D cyclic process is simulated using the following coupled composite solvers: the energy equation in the die and in the casting with solidification; filling of the casting by a droplet or a Navier-Stokes solver, and thermal stress analysis of the casting machine, casting and die during the cycle. This thermal analysis can be done for both starting and stopping transients and for the cyclic steady state. The software enables this analysis to be done almost automatically by designers. (author)

  10. Regimes Of Helium Burning

    CERN Document Server

    Timmes, F X

    2000-01-01

    The burning regimes encountered by laminar deflagrations and ZND detonations propagating through helium-rich compositions in the presence of buoyancy-driven turbulence are analyzed. Particular attention is given to models of X-ray bursts which start with a thermonuclear runaway on the surface of a neutron star, and the thin shell helium instability of intermediate-mass stars. In the X-ray burst case, turbulent deflagrations propagating in the lateral or radial directions encounter a transition from the distributed regime to the flamlet regime at a density of 10^8 g cm^{-3}. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than 10^6 g cm^{-3}. Self-sustained laminar deflagrations travelling in the radial direction cannot exist below this density. Similarily, the planar ZND detonation width becomes larger than the pressure scale height at 10^7 g cm^{-3}, suggesting that a steady-state, self-sustained detonations cannot come into exista...

  11. Effect of high pressure on mesophilic lactic fermentation streptococci

    Science.gov (United States)

    Reps, A.; Kuźmicka, M.; Wiśniewska, K.

    2008-07-01

    The research concerned the effect of high pressure on mesophilic lactic fermentation streptococci, present in two cheese-making commercial inocula produced by Christian-Hansen. Water solutions of inocula were pressurized at 50-800 MPa, at room temperature, for 30-120 min. Pressurization at 50-100 MPa slightly increased or reduced the number of lactic streptococci, depending on the inoculum and pressurization time. Pressurization at 200 MPa caused a reduction in the number of streptococci by over 99.9%, whereas the pressure of 400 MPa and above almost completely inactivated streptococci. Pressurization also reduced the dynamics of microorganism growth and acidification, to the degree depending on the pressure.

  12. Performance Improvement of Pulse Tube Refrigerator for Space Application with Helium-hydrogen mixture

    Science.gov (United States)

    Chen, G. B.; Yu, J. P.; Gan, Z. H.

    Weight or size of the cryocoolers used is a key factor in space applications This can be acquired by the selection of high efficiency cryocoolers or through the optimization of structural parameters. Given the type of regenerator, another way to improve the cooling performance is the adoption of gas mixture instead of pure helium as the working fluids. Gas mixtures have been proved very useful to J-T cryocoolers at 80K temperature range. In this paper, we do some theoretical and experimental study to probe into the possibility of using gas mixture to improve the coefficient of performance of regenerative cryocoolers such as pulse tube refrigerators. The performance comparison of regenerator using helium-hydrogen mixtures to pure helium gas is presented based on the analysis of the heat transfer and fluid flow. The pressure drop for helium-hydrogen mixture decreased more rapidly than the increase of thermal loss compared with pure helium, so the improvement of overall regenerator performance can be obtained. Experiments have been done with helium-hydrogen mixture in a coaxial valveless pulse tube refrigerator. Experimental results show that the cooling capacity with He-H2 mixture is 10~20 percent larger than that with pure helium, which is in coincidence with the theoretical analysis.

  13. Molecular dynamics study on the phase transition of high density helium%高密度氦相变的分子动力学研究∗

    Institute of Scientific and Technical Information of China (English)

    张宝玲; 宋小勇; 侯氢; 汪俊

    2015-01-01

    The melting curve of helium has been calculated over the temperature range of 0—1000 K using molecular dynamics method. Comparisons of the calculated melting curve and the experimental data show that the consistence between the melting curve and the experimental data may reach 500 K. When the temperature is above 600 K, no reliable experimental data have been found for comparison. In addition, the pressures inside the helium bubbles of various sizes existing in metal titanium are calculated and have a comparison with the melting curve. Results show that, at low temperatures, the helium bubbles may be in solid state as the temperature decreases. When the temperature is above 300 K, no solid helium bubble may exist.%采用分子动力学方法结合对关联函数分析计算了0—1000 K范围内氦的固—液相变曲线,与实验数据的对比显示,在0—500 K之间与实验数据符合很好,500 K以上还没有相应的实验数据。另外,计算了钛金属中不同尺寸氦泡的压强,并与高密度氦的固—液相变曲线进行了对比。结果显示,在低温条件下,随着温度的降低,钛晶体中可能会出现固态氦泡;在300 K以上不会存在固态氦泡。

  14. What about African Americans and High Blood Pressure?

    Science.gov (United States)

    ... whites. • Heredity —A tendency to have high blood pressure runs in families. • Age — In general, the older you get, the greater your chance of developing high blood pressure. • Sex — Men tend to develop high blood pressure ...

  15. Let's Talk about High Blood Pressure and Stroke

    Science.gov (United States)

    ... stroke. How does high blood pressure increase stroke risk? High blood pressure is the single most important risk factor for ... vessel ruptures over time. Who is at higher risk for HBP? People with a family history of high blood pressure African-Americans People age 35 or older People ...

  16. Metabolic Activity of Bacteria at High Pressure

    Science.gov (United States)

    Picard, A.; Daniel, I.; Oger, P.

    2008-12-01

    Over the last 20 years, there has been increasing evidence for the presence of a large number of microbes in the oceanic subsurface. Such a habitat has a very low energy input because it is deprived of light. A few meters below the sediment surface, conditions are already anoxic in most cases, sulfate reduction and/or methanogenesis becoming thus the primary respiratory reactions of organic matter. Neither the fate of methanogenesis, nor the fate of Dissimilatory Metal-Reduction (DMR) has been investigated so far as a function of pressure. For this reason, we measured experimentally the pressure limits of microbial anaerobic energetic metabolism. In practice, we measured in situ the kinetics of selenite respiration by the bacterial model Shewanella oneidensis MR-1 under high hydrostatic pressure (HHP) between 0 and 150 MPa at 30°C. MR-1 stationary-phase cells were used in Luria-Bertani (LB) medium amended with lactate as an additional electron donor and sodium selenite as an electron acceptor. In situ measurements were performed by X- ray Absorption Near-Edge Structure (XANES) spectroscopy in both a diamond-anvil cell and an autoclave. A red precipitate of amorphous Se(0) was virtually observed at any pressure to 150 MPa. A progressive reduction of selenite Se(IV) into selenium Se(0) was also observed in the evolution of XANES spectra with time. All kinetics between 0.1 and 150 MPa can be adjusted to a first order kinetic law. MR-1 respires all available selenite up to 60 MPa. Above 60 MPa, the respiration yield decreases linearly as a function of pressure and reaches 0 at 155 ±5 MPa. This indicates that selenite respiration by Shewanella oneidensis MR-1 stops at about 155 MPa, whereas its growth is arrested at 50 MPa. Hence, the present results show that the respiration of selenium by the strain MR-1 occurs efficiently up to 60 MPa and 30°C, i.e. from the surface of a continental sediment to an equivalent depth of about 2 km, or beneath a 5-km water column and

  17. Helium abundances and the helium isotope anomaly of sdB stars

    CERN Document Server

    Geier, S; Edelmann, H; Morales-Rueda, L; Kilkenny, D; O'Donoghue, D; Marsh, T R; Copperwheat, C

    2011-01-01

    Helium abundances and atmospheric parameters have been determined from high resolution spectra for a new sample of 46 bright hot subdwarf B (sdB) stars. The helium abundances have been measured with high accuracy. We confirm the correlation of helium abundance with temperature and the existence of two distinct sequences in helium abundance found previously. We focused on isotopic shifts of helium lines and found helium-3 to be strongly enriched in 8 of our programme stars. Most of these stars cluster in a small temperature range between 27000 K and 31000 K very similar to the known helium-3-rich main sequence B stars, which cluster at somewhat lower temperatures. This phenomenon is most probably related to diffusion processes in the atmosphere, but poses a challenge to diffusion models.

  18. Theoretical model of the helium zone plate microscope

    Science.gov (United States)

    Salvador Palau, Adrià; Bracco, Gianangelo; Holst, Bodil

    2017-01-01

    Neutral helium microscopy is a new technique currently under development. Its advantages are the low energy, charge neutrality, and inertness of the helium atoms, a potential large depth of field, and the fact that at thermal energies the helium atoms do not penetrate into any solid material. This opens the possibility, among others, for the creation of an instrument that can measure surface topology on the nanoscale, even on surfaces with high aspect ratios. One of the most promising designs for helium microscopy is the zone plate microscope. It consists of a supersonic expansion helium beam collimated by an aperture (skimmer) focused by a Fresnel zone plate onto a sample. The resolution is determined by the focal spot size, which depends on the size of the skimmer, the optics of the system, and the velocity spread of the beam through the chromatic aberrations of the zone plate. An important factor for the optics of the zone plate is the width of the outermost zone, corresponding to the smallest opening in the zone plate. The width of the outermost zone is fabrication limited to around 10 nm with present-day state-of-the-art technology. Due to the high ionization potential of neutral helium atoms, it is difficult to build efficient helium detectors. Therefore, it is crucial to optimize the microscope design to maximize the intensity for a given resolution and width of the outermost zone. Here we present an optimization model for the helium zone plate microscope. Assuming constant resolution and width of the outermost zone, we are able to reduce the problem to a two-variable problem (zone plate radius and object distance) and we show that for a given beam temperature and pressure, there is always a single intensity maximum. We compare our model with the highest-resolution zone plate focusing images published and show that the intensity can be increased seven times. Reducing the width of the outermost zone to 10 nm leads to an increase in intensity of more than 8000

  19. Comparison of high pressure transient PVT measurements and model predictions. Part I.

    Energy Technology Data Exchange (ETDEWEB)

    Felver, Todd G.; Paradiso, Nicholas Joseph; Evans, Gregory Herbert; Rice, Steven F.; Winters, William Stanley, Jr.

    2010-07-01

    A series of experiments consisting of vessel-to-vessel transfers of pressurized gas using Transient PVT methodology have been conducted to provide a data set for optimizing heat transfer correlations in high pressure flow systems. In rapid expansions such as these, the heat transfer conditions are neither adiabatic nor isothermal. Compressible flow tools exist, such as NETFLOW that can accurately calculate the pressure and other dynamical mechanical properties of such a system as a function of time. However to properly evaluate the mass that has transferred as a function of time these computational tools rely on heat transfer correlations that must be confirmed experimentally. In this work new data sets using helium gas are used to evaluate the accuracy of these correlations for receiver vessel sizes ranging from 0.090 L to 13 L and initial supply pressures ranging from 2 MPa to 40 MPa. The comparisons show that the correlations developed in the 1980s from sparse data sets perform well for the supply vessels but are not accurate for the receivers, particularly at early time during the transfers. This report focuses on the experiments used to obtain high quality data sets that can be used to validate computational models. Part II of this report discusses how these data were used to gain insight into the physics of gas transfer and to improve vessel heat transfer correlations. Network flow modeling and CFD modeling is also discussed.

  20. Helium liquefier cycles with saturated vapor compression

    Science.gov (United States)

    Minta, M.; Smith, J. L., Jr.

    The three refrigeration stages of the conventional helium liquefaction cycle are related to liquid nitrogen precooling, the use of expansion engines, and a J-T expansion. For an operation of helium refrigerators at temperatures below 4.2 K reduced pressure levels are required. Such an operation makes it necessary to enhance the compressor size and the heat exchanger surface area. In the case of 1.8 K refrigerators, practical cycles with three pressure levels are employed. It is pointed out that the saturated-vapor-compression (SVC) helium cycle provides an alternative solution to these problems. The present investigation is concerned with the design study of a SVC helium liquifier operating at elevated pressures. The study was conducted to demonstrate the potential of the SVC cycle on the basis of a direct comparison with a conventional cycle using the same precooling expanders and a supercritical wet expander instead of a J-T valve.

  1. Probing Hydrogen Diffusion under High Pressure

    Science.gov (United States)

    Bove, L. E.; Klotz, S.; Strassle, T.; Saitta, M.

    2012-12-01

    The study of the microscopic mechanism governing hydrogen and hydrogen-based liquids (as water, ammonia and methane) diffusion is crucial for a variety of scientific issues spanning most of natural sciences. As an example, characterizing hydrogen diffusion in a confined medium, like in porous systems or zeolites, is fundamental in problems relating to environment, hydrogen storage and industrial applications [1]. The presence of water diffusion in the minerals of the Earth's mantle have strong incidence on the processes governing volcanic eruptions and intermediate-depth seismicity. As last example, knowing in details the microscopic dynamics of hydrogen-based simple liquids under extreme conditions is essential in order to interpret observations and develop models of planet interiors [2]. On the other hand, water and other simple hydrogen-based liquids have always been key systems in the development of modern condensed-matter physics, because of their simple electronic structure and the peculiar properties deriving from the hydrogen-bond network. Their high compressibility and chemical reactivity have made these systems very challenging to study experimentally under static high P-T conditions. In the last few years, a large effort has been undertaken by several groups around the world [2] to extend the static and dynamic techniques to high temperatures and pressures, a program in which our group has been actively involved [3-6]. However, while the structure of water and other hydrogenated liquids of geological interest, is now known up to almost 20 GPa, the study of their transport properties greatly lags behind. We have recently developed a new large-volume gasket-anvil ensemble for the Paris-Edinburgh press based on a novel toroidal design [7], which allows to perform quasi elastic neutron scattering measurements on hydrogen based liquids up to one order of magnitude higher pressures (5 GPa) respect to what was achievable with standard methods [8]. The large

  2. Post irradiation characterization of beryllium and beryllides after high temperature irradiation up to 3000 appm helium production in HIDOBE-01

    Energy Technology Data Exchange (ETDEWEB)

    Fedorov, A.V., E-mail: fedorov@nrg.eu [Nuclear Research and Consultancy Group, Westerduinweg 3, Postbus 25, Petten, 1755 ZG (Netherlands); Til, S. van; Stijkel, M.P. [Nuclear Research and Consultancy Group, Westerduinweg 3, Postbus 25, Petten, 1755 ZG (Netherlands); Nakamichi, M. [Japan Atomic Energy Agency, Rokkasho (Japan); Zmitko, M. [The European Joint Undertaking for ITER and the Development of Fusion Energy, c/ Josep Pla, n° 2, Torres Diagonal Litoral, Edificio B3, Barcelona 08019 (Spain)

    2016-01-15

    Titanium beryllides are considered as advanced candidate material for neutron multiplier for the helium cooled pebble bed (HCPB) and/or the water cooled ceramic breeder (WCCB) breeder blankets. In the HIDOBE-01 (HIgh DOse irradiation of BEryllium) experiment, beryllium and beryllide pellets with 5 at% and 7 at% Ti are irradiated at four different target temperatures (T{sub irr}): 425 °C, 525 °C, 650 °C and 750 °C up to the dose corresponding to 3000 appm He production in beryllium. The pellets were supplied by JAEA. During post irradiation examinations the critical properties of volumetric swelling and tritium retention were studied. Both titanium beryllide grades show significantly less swelling than the beryllium grade, with the difference increasing with the irradiation temperature. The irradiation induced swelling was studied by using direct dimensions. Both beryllide grades showed much less swelling as compare to the reference beryllium grade. Densities of the grades were studied by Archimedean immersion and by He-pycnometry, giving indications of porosity formation. While both beryllide grades show no significant reduction in density at all irradiation temperatures, the beryllium density falls steeply at higher T{sub irr}. Finally, the tritium release and retention were studied by temperature programmed desorption (TPD). Beryllium shows the same strong tritium retention as earlier observed in studies on beryllium pebbles, while the tritium inventory of the beryllides is significantly less, already at the lowest T{sub irr} of 425 °C.

  3. Development of Helium-Mass-Spectrometry-Permeameter for the Measurement of Permeability of Near-Impermeable Rock

    Science.gov (United States)

    Lee, Moo Y.; Bauer, Stephen J.

    2016-12-01

    A helium leakage detection system was modified to measure gas permeability on extracted cores of nearly impermeable rock. The Helium-Mass-Spectrometry-Permeameter (HMSP) is duplicating the classic Darcy's experiment with a constant pressure differential and steady-state flow through a sample using helium gas. Under triaxial stress condition, the newly developed HMSP can measure hydraulic permeability of rocks and geomaterials down to the nanoDarcy scale (10-21 m2). The extension of measuring the lower end of the permeability scale may help answer important questions regarding the permeability of rock at great depth where fractures may close completely under high lithostatic stress.

  4. Low Pressure Adsorbent for Recovery & Storage Vented Hydrogen Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high performance fullerene-based adsorbent is proposed for recovery and storage hydrogen and separating helium via pressure-swing-adsorption (PSA) process....

  5. Calculated Regenerator Performance at 4 K with HELIUM-4 and HELIUM-3

    Science.gov (United States)

    Radebaugh, Ray; Huang, Yonghua; O'Gallagher, Agnes; Gary, John

    2008-03-01

    The helium-4 working fluid in regenerative cryocoolers operating with the cold end near 4 K deviates considerably from an ideal gas. As a result, losses in the regenerator, given by the time-averaged enthalpy flux, are increased and are strong functions of the operating pressure and temperature. Helium-3, with its lower boiling point, behaves somewhat closer to an ideal gas in this low temperature range and can reduce the losses in 4 K regenerators. An analytical model is used to find the fluid properties that strongly influence the regenerator losses as well as the gross refrigeration power. The thermodynamic and transport properties of helium-3 were incorporated into the latest NIST regenerator numerical model, known as REGEN3.3, which was used to model regenerator performance with either helium-4 or helium-3. With this model we show how the use of helium-3 in place of helium-4 can improve the performance of 4 K regenerative cryocoolers. The effects of operating pressure, warm-end temperature, and frequency on regenerators with helium-4 and helium-3 are investigated and compared. The results are used to find optimum operating conditions. The frequency range investigated varies from 1 Hz to 30 Hz, with particular emphasis on higher frequencies.

  6. Fluid phase thermodynamics : I) nucleate pool boiling of oxygen under magnetically enhanced gravity and II) superconducting cavity resonators for high-stability frequency references and precision density measurements of helium-4 gas

    Science.gov (United States)

    Corcovilos, Theodore Allen

    Although fluids are typically the first systems studied in undergraduate thermodynamics classes, we still have only a rudimentary phenomenological understanding of these systems outside of the classical and equilibrium regimes. Two experiments will be presented. First, we present progress on precise measurements of helium-4 gas at low temperatures (1 K-5 K). We study helium because at low densities it is an approximately ideal gas but at high densities the thermodynamic properties can be predicted by numerical solutions of Schroedinger's equation. By utilizing the high resolution and stability in frequency of a superconducting microwave cavity resonator we can measure the dielectric constant of helium-4 to parts in 109, corresponding to an equivalent resolution in density. These data will be used to calculate the virial coefficients of the helium gas so that we may compare with numerical predictions from the literature. Additionally, our data may allow us to measure Boltzmann's constant to parts in 108, a factor of 100 improvement over previous measurements. This work contains a description of the nearly-completed apparatus and the methods of operation and data analysis for this experiment. Data will be taken by future researchers.The second experiment discussed is a study of nucleate pool boiling. To date, no adequate quantitative model exists of this everyday phenomenon. In our experiment, we vary one parameter inaccessible to most researchers, gravity, by applying a magnetic force to our test fluid, oxygen. Using this technique, we may apply effective gravities of 0-80 times Earth's gravitational acceleration (g). In this work we present heat transfer data for the boiling of oxygen at one atmosphere ambient pressure for effective gravity values between 1g and 16g . Our data describe two relationships between applied heat flux and temperature differential: at low heat flux the system obeys a power law and at high heat flux the behavior is linear. We find that the

  7. High-pressure superconducting state in hydrogen

    Science.gov (United States)

    Duda, A. M.; Szczȩśniak, R.; Sowińska, M. A.; Kosiacka, A. H.

    2016-10-01

    The paper determines the thermodynamic parameters of the superconducting state in the metallic atomic hydrogen under the pressure at 1 TPa, 1.5 TPa, and 2.5 TPa. The calculations were conducted in the framework of the Eliashberg formalism. It has been shown that the critical temperature is very high (in the range from 301.2 K to 437.3 K), as well as high are the values of the electron effective mass (from 3.43me to 6.88me), where me denotes the electron band mass. The ratio of the low-temperature energy gap to the critical temperature explicitly violates the predictions of the BCS theory: 2 Δ (0) /kB TC ∈ . Additionally, the free energy difference between the superconducting and normal state, the thermodynamic critical field, and the specific heat of the superconducting state have been determined. Due to the significant strong-coupling and retardation effects those quantities cannot be correctly described in the framework of the BCS theory.

  8. High-pressure Raman spectroscopy of carbon onions and nanocapsules

    Science.gov (United States)

    Guo, J. J.; Liu, G. H.; Wang, X. M.; Fujita, T.; Xu, B. S.; Chen, M. W.

    2009-08-01

    We report high-pressure Raman spectra of carbon onions and nanocapsules investigated by diamond anvil cell experiments. The pressure coefficient and elastic behavior of carbon onions and nanocapsules are found to be very similar to those of multiwall carbon nanotubes. Additionally, detectable structure changes, particularly the collapse of the concentric graphite structure, cannot been seen at pressures as high as ˜20 GPa, demonstrating that carbon onions and nanocapsules have significant hardness and can sustain very high pressures.

  9. High Chamber Pressure, Light Weight Thrusters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The performance liquid propellant engines can be significantly improved by increasing both combustion temperature and pressure and reducing engine weight. State of...

  10. Cryogenic infrastructure for superfluid helium testing of LHC prototype superconducting magnets

    Energy Technology Data Exchange (ETDEWEB)

    Benda, V.; Duraffour, G.; Guiard-Marigny, A.; Lebrun, Ph.; Momal, F.; Saban, R.; Sergo, V.; Tavian, L.; Vullierme, B. [CERN, Geneva (Switzerland)

    1994-12-31

    The Large Hadron Collider (LHC) project at CERN will require about 1800 high-field superconducting magnets, operating below 1.9 K in pressurized helium II. All magnets will be reception-tested before their installation in the 26.7 km circumference ring tunnel. For this purpose, the authors have installed large-capacity cryogenic facilities, beginning to operate for tests of full-scale prototype magnets produced by European industry. Based around a 6 kW@4.5 K helium refrigerator and a 25 m{sup 3} liquid helium storage, the system includes a low-pressure, 6 to 18 g/s helium pumping unit for 1.8 K refrigeration, a set of magnet cooldown and warmup units delivering each up to 120 kW of refrigeration at precisely controlled temperature, and a network of cryogenic lines for transferring liquid nitrogen, liquid helium and cold gaseous helium. All components are controlled by embedded PLCs, connected to a general supervision system for operator interface. The authors present the system layout and describe the design and performance of the main components.

  11. An experiment to measure the spectra of primary proton, helium and iron nuclei at the 'knee' region at a high altitude

    CERN Document Server

    Xu, X W; Ding, L K; Zhang, C S; Ohnishi, M

    2003-01-01

    The possibility of measuring the energy spectra of some single elements (proton, helium and iron) in primary cosmic rays at the 'knee' energies, by setting up an air shower (AS) core detector in the AS gamma array (4300 m a.s.l., Tibet, China) is investigated. Taking into account the sensitivity and the acceptance needed for this measurement, the feasibility of construction and operation of the apparatus at a high altitude, and the cost, it is shown that this aim can be achieved by a simple AS core detector that mainly measures the high-energy electromagnetic components in AS cores. In this paper, such a detector is described. With a three-year exposure, proton, helium and iron spectra at the 'knee' energy region can be obtained with three event samples selected by an artificial neural network (ANN).

  12. Numerical simulation of high pressure water jet impacting concrete

    Science.gov (United States)

    Liu, Jialiang; Wang, Mengjin; Zhang, Di

    2017-08-01

    High pressure water jet technology is an unconventional concrete crushing technology. In order to reveal the mechanism of high pressure water jet impacting concrete, it built a three-dimensional numerical model of high pressure water jet impacting concrete based on fluid mechanics and damage mechanics. And the numerical model was verified by theoretical analysis and experiments. Based on this model, it studied the stress characteristics in concrete under high pressure water jet impacting at different time, and quantified the damage evolution rules in concrete along the water jet radial direction. The results can provide theoretical basis and guidance for the high pressure water jet crushing concrete technology.

  13. High-power helium-neon laser irradiation inhibits the growth of traumatic scars in vitro and in vivo.

    Science.gov (United States)

    Shu, Bin; Ni, Guo-Xin; Zhang, Lian-Yang; Li, Xiang-Ping; Jiang, Wan-Ling; Zhang, Li-Qun

    2013-05-01

    This study explored the inhibitory effect of the high-power helium-neon (He-Ne) laser on the growth of scars post trauma. For the in vitro study, human wound fibroblasts were exposed to the high-power He-Ne laser for 30 min, once per day with different power densities (10, 50, 100, and 150 mW/cm(2)). After 3 days of repeated irradiation with the He-Ne laser, fibroblast proliferation and collagen synthesis were evaluated. For in vivo evaluation, a wounded animal model of hypertrophic scar formation was established. At postoperative day 21, the high-power He-Ne laser irradiation (output power 120 mW, 6 mm in diameter, 30 min each session, every other day) was performed on 20 scars. At postoperative day 35, the hydroxyproline content, apoptosis rate, PCNA protein expression and FADD mRNA level were assessed. The in vitro study showed that the irradiation group that received the power densities of 100 and 150 mW/cm(2) showed decreases in the cell proliferation index, increases in the percentage of cells in the G0/G1 phase, and decreases in collagen synthesis and type I procollagen gene expression. In the in vivo animal studies, regions exposed to He-Ne irradiation showed a significant decrease in scar thickness as well as decreases in hydroxyproline levels and PCNA protein expression. Results from the in vitro and in vivo studies suggest that repeated irradiation with a He-Ne laser at certain power densities inhibits fibroblast proliferation and collagen synthesis, thereby inhibits the growth of hypertrophic scars.

  14. Charging dynamics of dopants in helium nanoplasmas

    DEFF Research Database (Denmark)

    Heidenreich, Andreas; Grüner, Barbara; Schomas, Dominik

    2017-01-01

    We present a combined experimental and theoretical study of the charging dynamics of helium nanodroplets doped with atoms of different species and irradiated by intense near-infrared laser pulses (≤1015 W cm−2). In particular, we elucidate the interplay of dopant ionization inducing the ignition...... of a helium nanoplasma, and the charging of the dopant atoms driven by the ionized helium host. Most efficient nanoplasma ignition and charging is found when doping helium droplets with xenon atoms, in which case high charge states of both helium (He2+) and of xenon (Xe21+) are detected. In contrast, only low...... charge states of helium and dopants are measured when doping with potassium and calcium atoms. Classical molecular dynamics simulations which include focal averaging generally reproduce the experimental results and provide detailed insights into the correlated charging dynamics of guest and host clusters....

  15. Automated high pressure cell for pressure jump x-ray diffraction

    Science.gov (United States)

    Brooks, Nicholas J.; Gauthe, Beatrice L. L. E.; Terrill, Nick J.; Rogers, Sarah E.; Templer, Richard H.; Ces, Oscar; Seddon, John M.

    2010-06-01

    A high pressure cell for small and wide-angle x-ray diffraction measurements of soft condensed matter samples has been developed, incorporating a fully automated pressure generating network. The system allows both static and pressure jump measurements in the range of 0.1-500 MPa. Pressure jumps can be performed as quickly as 5 ms, both with increasing and decreasing pressures. Pressure is generated by a motorized high pressure pump, and the system is controlled remotely via a graphical user interface to allow operation by a broad user base, many of whom may have little previous experience of high pressure technology. Samples are loaded through a dedicated port allowing the x-ray windows to remain in place throughout an experiment; this facilitates accurate subtraction of background scattering. The system has been designed specifically for use at beamline I22 at the Diamond Light Source, United Kingdom, and has been fully integrated with the I22 beamline control systems.

  16. Automated high pressure cell for pressure jump x-ray diffraction.

    Science.gov (United States)

    Brooks, Nicholas J; Gauthe, Beatrice L L E; Terrill, Nick J; Rogers, Sarah E; Templer, Richard H; Ces, Oscar; Seddon, John M

    2010-06-01

    A high pressure cell for small and wide-angle x-ray diffraction measurements of soft condensed matter samples has been developed, incorporating a fully automated pressure generating network. The system allows both static and pressure jump measurements in the range of 0.1-500 MPa. Pressure jumps can be performed as quickly as 5 ms, both with increasing and decreasing pressures. Pressure is generated by a motorized high pressure pump, and the system is controlled remotely via a graphical user interface to allow operation by a broad user base, many of whom may have little previous experience of high pressure technology. Samples are loaded through a dedicated port allowing the x-ray windows to remain in place throughout an experiment; this facilitates accurate subtraction of background scattering. The system has been designed specifically for use at beamline I22 at the Diamond Light Source, United Kingdom, and has been fully integrated with the I22 beamline control systems.

  17. Selected studies of magnetism at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Hearne, G.R. [University of the Witwatersrand, Johannesburg (South Africa). Dept. of Physics; Pasternak, M.P. [Tel-Aviv Univ. (Israel). School of Physics and Astronomy; Taylor, R.D. [Los Alamos National Lab., NM (United States)

    1995-09-01

    Most previous studies of magnetism in various compounds under extreme conditions have been conducted over a wide pressure range at room temperature or over a wide range of cryogenic temperatures at pressures below 20 GPa (200 kbar). We present some of the most recent studies of magnetism over an extended range of temperatures and pressures far beyond 20 GPa, i.e., in regions of pressure-temperature (P-T) where magnetism has been largely unexplored. Recent techniques have permitted investigations of magnetism in selected 3d transition metal compounds in regions of P-T where physical properties may be drastically modified; related effects have often been seen in selected doping studies at ambient pressures.

  18. Equation of state of unreacted high explosives at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, C-S

    1998-08-14

    Isotherms of unreacted high explosives (HMX, RDX, and PETN) have been determined to quasi-hydrostatic high pressures below 45 GPa, by using a diamond-anvil cell angle-resolved synchrotron x-ray diffraction method. The equation-of-state parameters (bulk modulus Bo, and its derivatives B' ) are presented for the 3rd-order Birch-Murnaghan formula based on the measured isotherms. The results are also used to retrieve unreacted Hugoniots in these high explosives and to develop the equations of state and kinetic models for composite high explolsivcs such as XTX-8003 and LX-04. The evidence of shear-induced chemistry of HMX in non-hydrostatic conditions is also presented.

  19. High Pressure Laminates with Antimicrobial Properties

    Directory of Open Access Journals (Sweden)

    Sandra Magina

    2016-02-01

    Full Text Available High-pressure laminates (HPLs are durable, resistant to environmental effects and good cost-benefit decorative surface composite materials with special properties tailored to meet market demand. In the present work, polyhexamethylene biguanide (PHMB was incorporated for the first time into melamine-formaldehyde resin (MF matrix on the outer layer of HPLs to provide them antimicrobial properties. Chemical binding of PHMB to resin matrix was detected on the surface of produced HPLs by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR. Antimicrobial evaluation tests were carried out on the ensuing HPLs doped with PHMB against gram-positive Listeria innocua and gram-negative Escherichia coli bacteria. The results revealed that laminates prepared with 1.0 wt % PHMB in MF resin were bacteriostatic (i.e., inhibited the growth of microorganisms, whereas those prepared with 2.4 wt % PHMB in MF resin exhibited bactericidal activity (i.e., inactivated the inoculated microorganisms. The results herein reported disclose a promising strategy for the production of HPLs with antimicrobial activity without affecting basic intrinsic quality parameters of composite material.

  20. Spectroscopy of high pressure cesium discharge

    Science.gov (United States)

    Pichler, Goran; Pichler, Marin

    2008-05-01

    Near UV, visible and NIR spectrum of Cs lamp has been studied in many experimental situations. We concentrate on the spectral region around resonance lines where numerous satellite bands appear. We followed the appearance of these satellite bands after the ignition. They first appear in emission, and then in absorption, due to the steady increase of cesium atom density. The origin of the satellite bands have been described ootnotetextD. Veza, R. Beuc, S. Milosevi' c and G. Pichler, Eur. Phys. J. D, 2, 45 (1998)^,ootnotetextR. Beuc, H. Skenderovi' c, T. Ban, D. Veza, G. Pichler, W. Meyer, Eur. Phys. J.D 15, 209 (2001). We observed the satellite band intensity behavior in several different burners filled with cesium and xenon. In one burner made out of crystalline sapphire we observed interesting spatial distribution of entire visible spectrum, during evolution in time after the ignition. The intensity behavior of satellite bands in the near-infrared spectral region will be used in further development of the white light source with pulsed cesium high-pressure discharge.