Science.gov

Sample records for high temperature dense

  1. Dense high temperature ceramic oxide superconductors

    DOEpatents

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  2. Dense high temperature ceramic oxide superconductors

    DOEpatents

    Landingham, R.L.

    1993-10-12

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  3. Vibrational spectroscopy in high temperature dense fluids

    SciTech Connect

    Moore, D.S.; Schmidt, S.C.

    1992-01-01

    Coherent anti-Stokes Raman spectroscopy (CARS) in conjunction with a two-stage light-gas gun has been used to obtain vibrational spectra of shock-compressed liquid N{sub 2}, O{sub 2}, CO, and their mixtures, as well as liquid N{sub 2}O. The experimental spectra are compared to spectra calculated using a semiclassical model for CARS intensities to obtain vibrational frequencies, peak Raman susceptibilities, and linewidths. The derived spectroscopic parameters suggest thermal equilibrium of the vibrational populations is established in less than a few nanoseconds after shock passage. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations. The variation of the vibrational frequency shift at pressure with species concentration in mixtures is investigated.

  4. Dense simple plasmas as high-temperature liquid simple metals

    NASA Technical Reports Server (NTRS)

    Perrot, F.

    1990-01-01

    The thermodynamic properties of dense plasmas considered as high-temperature liquid metals are studied. An attempt is made to show that the neutral pseudoatom picture of liquid simple metals may be extended for describing plasmas in ranges of densities and temperatures where their electronic structure remains 'simple'. The primary features of the model when applied to plasmas include the temperature-dependent self-consistent calculation of the electron charge density and the determination of a density and temperature-dependent ionization state.

  5. RAPID COMMUNICATION: The dissipative effect of thermal radiation loss in high-temperature dense plasmas

    NASA Astrophysics Data System (ADS)

    Li, L. H.; Zhang, H. Q.

    1996-08-01

    A dynamical model based on the two-fluid dynamical equations with energy generation and loss is obtained and used to investigate the self-generated magnetic fields in high-temperature dense plasmas such as the solar core. The self-generation of magnetic fields might be looked at as a self-organization-type behaviour of stochastic thermal radiation fields, as expected for an open dissipative system according to Prigogine's theory of dissipative structures.

  6. Synthesis of Dense BC3 Phases under High-Pressure and High-Temperature

    NASA Astrophysics Data System (ADS)

    Zinin, P.; Ming, L.; Acosta, T.; Jia, R.; Hellebrand, E.; Ishii, H.

    2010-12-01

    The finding of the new diamond-like B-C phases is of fundamental importance. These phases are potential high-temperature superconductors and their development is important for understanding the nature of high-temperature superconductivity (Moussa, Cohen, Phys. Rev. B, 77, 064518 2008). They will shed light on the nature of the bonding of the boron atoms in a diamond-like structure. Recently, theoretical simulations of pressure- and temperature-induced phase transition in the B-C system demonstrated that the incorporation of B atoms into a diamond structure should not lead to a drastic distortion of the cubic cell of a diamond (Lowther, J. Phys. Condense Matter. 17, 3221, 2005). In this report we present data on the synthesis of new dense phases cubic BC3 (c-BC3) phase from graphitic BC3 phase (g-BC3) phase under high pressure and high temperature. Two graphitic polycrystalline BCx samples were compressed in a diamond-anvil cell to about 24 GPa and 45 GPa, respectively, and then were laser-heated to ~2000 K. After quenching, each sample was decompressed gradually stepwise to the atmospheric pressure. Synchrotron-based X-ray diffraction patterns were taken before and after the laser-heating, and also at each pressure step-down. The experimental data showed that two new phases were synthesized: (a) an orthorhombic phase with a0 = 3.74 Å, b0 = 3.24 Å, c0=4.25 Å; and (b) a cubic phase with a0 = 3.587Å recovered from 24 GPa and 44 GPa, respectively. The zero-pressure lattice parameter of the cubic phase obtained in this study is larger than that of diamond (i.e., a0=3.5667 Å, ASTM # 6-0675), which is consistent with theoretical prediction The micro-Raman measurements were directly performed on the new phases. The Raman spectra excited by a green (Nd-YAG, 532-nm) laser were taken with a confocal Raman system (WiTec alpha300). The Raman spectrum of the c-BC3 phase is similar to that of diamond-like BC3 phase (Zinin et al., J. Raman Spectrosc., 38, 1362, 2007) with a

  7. Synthesis of dense BC[subscript x] phases under high-pressure and high-temperature

    SciTech Connect

    Ming, L.C.; Zinin, P.V.; Liu, X.R.; Nakamoto, Y.; Jia, R.

    2010-05-24

    We synthesized a new phase from the B-C system, cubic BC{sub 4} (c-BC{sub 4}), by direct transformation from graphitic phases at a pressure of 44 GPa and a temperature 2020 K in a laser-heated diamond anvil cell (DAC). Both x-ray diffraction and Raman spectroscopy confirm the presence of cubic BC{sub 4} from the sample recovered at ambient conditions. The zero-pressure lattice parameter of the c-BC{sub 4} calculated from diffraction peaks was found to be 3.587 {angstrom}. The composition of the new phase is determined from electron microprobe (EMP) measurements. The value of the C/B ratio is around 4 (3.91 {+-} 0.26).

  8. Method of forming a dense, high temperature electronically conductive composite layer on a porous ceramic substrate

    DOEpatents

    Isenberg, Arnold O.

    1992-01-01

    An electrochemical device, containing a solid oxide electrolyte material and an electrically conductive composite layer, has the composite layer attached by: (A) applying a layer of LaCrO.sub.3, YCrO.sub.3 or LaMnO.sub.3 particles (32), on a portion of a porous ceramic substrate (30), (B) heating to sinter bond the particles to the substrate, (C) depositing a dense filler structure (34) between the doped particles (32), (D) shaving off the top of the particles, and (E) applying an electronically conductive layer over the particles (32) as a contact.

  9. Method of forming a dense, high temperature electronically conductive composite layer on a porous ceramic substrate

    DOEpatents

    Isenberg, A.O.

    1992-04-21

    An electrochemical device, containing a solid oxide electrolyte material and an electrically conductive composite layer, has the composite layer attached by: (A) applying a layer of LaCrO[sub 3], YCrO[sub 3] or LaMnO[sub 3] particles, on a portion of a porous ceramic substrate, (B) heating to sinter bond the particles to the substrate, (C) depositing a dense filler structure between the doped particles, (D) shaving off the top of the particles, and (E) applying an electronically conductive layer over the particles as a contact. 7 figs.

  10. Temperature relaxation in dense plasma mixtures

    NASA Astrophysics Data System (ADS)

    Faussurier, Gérald; Blancard, Christophe

    2016-09-01

    We present a model to calculate temperature-relaxation rates in dense plasma mixtures. The electron-ion relaxation rates are calculated using an average-atom model and the ion-ion relaxation rates by the Landau-Spitzer approach. This method allows the study of the temperature relaxation in many-temperature electron-ion and ion-ion systems such as those encountered in inertial confinement fusion simulations. It is of interest for general nonequilibrium thermodynamics dealing with energy flows between various systems and should find broad use in present high energy density experiments.

  11. Temperature Measurements of Dense Plasmas by Detailed Balance

    SciTech Connect

    Holl, A; Redmer, R; Ropke, G; Reinholz, H; Thiele, R; Fortmann, C; Forster, E; Cao, L; Tschentscher, T; Toleikis, S; Glenzer, S H

    2006-03-14

    Plasmas at high electron densities of n{sub e} = 10{sup 20} - 10{sup 26} cm{sup -3} and moderate temperatures T{sub e} = 1 - 20 eV are important for laboratory astrophysics, high energy density science and inertial confinement fusion. These plasmas are usually referred to as Warm Dense Matter (WDM) and are characterized by a coupling parameter of {Lambda} {approx}> 1 where correlations become important. The characterization of such plasmas is still a challenging task due to the lack of direct measurement techniques for temperatures and densities. They propose to measure the Thomson scattering spectrum of vacuum-UV radiation off density fluctuations in the plasma. Collective Thomson scattering provides accurate data for the electron temperature applying first principles. Further, this method takes advantage of the spectral asymmetry resulting from detailed balance and is independent of collisional effects in these dense systems.

  12. Novel strategy for low-temperature, high-rate growth of dense, hard, and stress-free refractory ceramic thin films

    SciTech Connect

    Greczynski, Grzegorz Lu, Jun; Hultman, Lars; Bolz, Stephan; Kölker, Werner; Schiffers, Christoph; Lemmer, Oliver; Petrov, Ivan; Greene, Joseph E.

    2014-07-01

    Growth of fully dense refractory thin films by means of physical vapor deposition (PVD) requires elevated temperatures T{sub s} to ensure sufficient adatom mobilities. Films grown with no external heating are underdense, as demonstrated by the open voids visible in cross-sectional transmission electron microscopy images and by x-ray reflectivity results; thus, the layers exhibit low nanoindentation hardness and elastic modulus values. Ion bombardment of the growing film surface is often used to enhance densification; however, the required ion energies typically extract a steep price in the form of residual rare-gas-ion-induced compressive stress. Here, the authors propose a PVD strategy for the growth of dense, hard, and stress-free refractory thin films at low temperatures; that is, with no external heating. The authors use TiN as a model ceramic materials system and employ hybrid high-power pulsed and dc magnetron co-sputtering (HIPIMS and DCMS) in Ar/N{sub 2} mixtures to grow dilute Ti{sub 1−x}Ta{sub x}N alloys on Si(001) substrates. The Ta target driven by HIPIMS serves as a pulsed source of energetic Ta{sup +}/Ta{sup 2+} metal–ions, characterized by in-situ mass and energy spectroscopy, while the Ti target operates in DCMS mode (Ta-HIPIMS/Ti-DCMS) providing a continuous flux of metal atoms to sustain a high deposition rate. Substrate bias V{sub s} is applied in synchronous with the Ta-ion portion of each HIPIMS pulse in order to provide film densification by heavy-ion irradiation (m{sub Ta} = 180.95 amu versus m{sub Ti} = 47.88 amu) while minimizing Ar{sup +} bombardment and subsequent trapping in interstitial sites. Since Ta is a film constituent, primarily residing on cation sublattice sites, film stress remains low. Dense Ti{sub 0.92}Ta{sub 0.08}N alloy films, 1.8 μm thick, grown with T{sub s} ≤ 120 °C (due to plasma heating) and synchronized bias, V{sub s} = 160 V, exhibit nanoindentation hardness H = 25.9 GPa and

  13. Electron-ion temperature equilibration in warm dense tantalum

    SciTech Connect

    Doppner, T; LePape, S.; Ma, T.; Pak, A.; Hartley, N. J.; Peters, L.; Gregori, G.; Belancourt, P.; Drake, R. P.; Chapman, D. A.; Richardson, S.; Gericke, D. O.; Glenzer, S. H.; Khaghani, D.; Neumayer, P.; Vorberger, J.; White, T. G.

    2014-11-05

    We present measurements of electron-ion temperature equilibration in proton-heated tantalum, under warm dense matter conditions. Our results agree with theoretical predictions for metals calculated using input data from ab initio simulations. Furthermore, the fast relaxation observed in the experiment contrasts with much longer equilibration times found in proton heated carbon, indicating that the energy flow pathways in warm dense matter are far from being fully understood.

  14. Electron-ion temperature equilibration in warm dense tantalum

    DOE PAGES

    Doppner, T; LePape, S.; Ma, T.; Pak, A.; Hartley, N. J.; Peters, L.; Gregori, G.; Belancourt, P.; Drake, R. P.; Chapman, D. A.; et al

    2014-11-05

    We present measurements of electron-ion temperature equilibration in proton-heated tantalum, under warm dense matter conditions. Our results agree with theoretical predictions for metals calculated using input data from ab initio simulations. Furthermore, the fast relaxation observed in the experiment contrasts with much longer equilibration times found in proton heated carbon, indicating that the energy flow pathways in warm dense matter are far from being fully understood.

  15. Ion-temperature-gradient driven modes in very dense magnetoplasmas

    NASA Astrophysics Data System (ADS)

    Mirza, Arshad M.; Shukla, P. K.

    2008-02-01

    By employing the quantum magnetohydrodynamic-Poisson model, a general dispersion relation for low-frequency electrostatic ion-temperature-gradient (ITG) modes in a very dense Fermi plasma is derived. The growth rate is found to be higher in the presence of ion-temperature gradients and electron corrections due to quantum fluctuations. Two new ITG driven modes in the Fermi plasma are found. These ITG modes are associated with an electron density response that differs from the Boltzmann law. It is expected that newly found ITG modes can play an important role in anomalous cross-field ion energy transport in the next-generation laser-solid density plasma experiments as well as in dense astrophysical bodies (e.g., neutron stars and the interior of white dwarfs).

  16. Experimental measurement of speeds of sound in dense supercritical carbon monoxide and development of a high-pressure, high-temperature equation of state.

    PubMed

    Zaug, Joseph M; Carter, Jeffrey A; Bastea, Sorin; Armstrong, Michael R; Crowhurst, Jonathan C; Fried, Laurence E

    2013-05-01

    We report the adiabatic sound speeds for supercritical fluid carbon monoxide along two isotherms, from 0.17 to 2.13 GPa at 297 K and from 0.31 to 3.2 GPa at 600 K. The carbon monoxide was confined in a resistively heated diamond-anvil cell, and the sound speed measurements were conducted in situ using a recently reported variant of the photoacoustic light scattering effect. The measured sound speeds were then used to parametrize a single site dipolar exponential-6 intermolecular potential for carbon monoxide. PρT thermodynamic states, sound speeds, and shock Hugoniots were calculated using the newly parametrized intermolecular potential and compared to previously reported experimental results. Additionally, we generated an analytical equation of state for carbon monoxide by fitting to a grid of calculated PρT states over a range of 0.1-10 GPa and 150-2000 K. A 2% mean variation was found between computed high-pressure solid-phase densities and measured data-a surprising result for a spherical interaction potential. We further computed a rotationally dependent fluid to β-solid phase boundary; results signal the relative magnitude of short-range rotational disorder under conditions that span existing phase boundary measurements. PMID:23586650

  17. Superconductivity in highly disordered dense carbon disulfide.

    PubMed

    Dias, Ranga P; Yoo, Choong-Shik; Struzhkin, Viktor V; Kim, Minseob; Muramatsu, Takaki; Matsuoka, Takahiro; Ohishi, Yasuo; Sinogeikin, Stanislav

    2013-07-16

    High pressure plays an increasingly important role in both understanding superconductivity and the development of new superconducting materials. New superconductors were found in metallic and metal oxide systems at high pressure. However, because of the filled close-shell configuration, the superconductivity in molecular systems has been limited to charge-transferred salts and metal-doped carbon species with relatively low superconducting transition temperatures. Here, we report the low-temperature superconducting phase observed in diamagnetic carbon disulfide under high pressure. The superconductivity arises from a highly disordered extended state (CS4 phase or phase III[CS4]) at ~6.2 K over a broad pressure range from 50 to 172 GPa. Based on the X-ray scattering data, we suggest that the local structural change from a tetrahedral to an octahedral configuration is responsible for the observed superconductivity.

  18. Molecular Dynamics Simulations of Temperature Equilibration in Dense Hydrogen

    SciTech Connect

    Glosli, J; Graziani, F; More, R; Murillo, M; Streitz, F; Surh, M; Benedict, L; Hau-Riege, S; Langdon, A; London, R

    2008-02-14

    The temperature equilibration rate in dense hydrogen (for both T{sub i} > T{sub e} and T{sub i} < T{sub e}) has been calculated with large-scale molecular dynamics simulations for temperatures between 10 and 300 eV and densities between 10{sup 20}/cc to 10{sup 24}/cc. Careful attention has been devoted to convergence of the simulations, including the role of semiclassical potentials. We find that for Coulomb logarithms L {approx}> 1, Brown-Preston-Singleton [Brown et al., Phys. Rep. 410, 237 (2005)] with the sub-leading corrections and the fit of Gericke-Murillo-Schlanges [Gericke et al., PRE 65, 036418 (2003)] to the T-matrix evaluation of the collision operator, agrees with the MD data to within the error bars of the simulation. For more strongly-coupled plasmas where L {approx}< 1, our numerical results are consistent with the fit of Gericke-Murillo-Schlanges.

  19. High Temperature Alkali Corrosion of Dense SN4 Coated with CMZP and Mg-Doped A21TiO5 in Coal Gas

    SciTech Connect

    J. J. Brown; Nguyen Thierry

    1997-10-01

    Si3N4 heat exchangers used in industrial systems are usually operating in harsh environments. Not only is this structural material experiencing high temperatures, but it is also subjected to corrosive gases and condensed phases. Past studies have demonstrated that condensed phases severely attack Si3N4 and as a consequence, dramatically reduce its lifetime in industrial operating systems.1,2 Previous research conducted at Virginia Tech on low thermal expansion coefficient oxide ceramics,3,4,5 (Ca1-X,MgX)Zr4(PO4)6 (CMZP), and Mg-doped Al2TiO5, for structural application have shown that these two materials exhibited better resistance to alkaline corrosion than Si3N4. Thus, they were envisioned as good candidates for a protective coating on Si3N4 heat exchangers. As a result, the goal of the present work is to develop CMZP and Mg-doped Al2TiO5 protective thin films using the sol-gel process and the dip coating technique and to test their effectiveness in an alkali-containing atmosphere.

  20. Temperature scaling in a dense vibrofluidized granular material.

    PubMed

    Sunthar, P; Kumaran, V

    1999-08-01

    The leading order "temperature" of a dense two-dimensional granular material fluidized by external vibrations is determined. The grain interactions are characterized by inelastic collisions, but the coefficient of restitution is considered to be close to 1, so that the dissipation of energy during a collision is small compared to the average energy of a particle. An asymptotic solution is obtained where the particles are considered to be elastic in the leading approximation. The velocity distribution is a Maxwell-Boltzmann distribution in the leading approximation. The density profile is determined by solving the momentum balance equation in the vertical direction, where the relation between the pressure and density is provided by the virial equation of state. The temperature is determined by relating the source of energy due to the vibrating surface and the energy dissipation due to inelastic collisions. The predictions of the present analysis show good agreement with simulation results at higher densities where theories for a dilute vibrated granular material, with the pressure-density relation provided by the ideal gas law, are in error. PMID:11969987

  1. Lower sintering temperature of nanostructured dense ceramics compacted from dry nanopowders using powerful ultrasonic action

    NASA Astrophysics Data System (ADS)

    Khasanov, O.; Reichel, U.; Dvilis, E.; Khasanov, A.

    2011-10-01

    Nanostructured high dense zirconia ceramics have been sintered from dry nanopowders compacted by uniaxial pressing with simultaneous powerful ultrasonic action (PUA). Powerful ultrasound with frequency of 21 kHz was supplied from ultrasonic generator to the mold, which was the ultrasonic wave-guide. Previously the mold was filled by non-agglomerated zirconia nanopowder having average particle size of 40 nm. Any binders or plasticizers were excluded at nanopowder processing. Compaction pressure was 240 MPa, power of ultrasonic generator at PUA was 1 kW and 3 kW. The fully dense zirconia ceramics has been sintered at 1345°C and high-dense ceramics with a density of 99.1%, the most grains of which had the sizes Dgr <= 200 nm, has been sintered at low sintering temperature (1325°C). Applied approach prevents essential grain growth owing to uniform packing of nanoparticles under vibrating PU-action at pressing, which provides the friction forces control during dry nanopowder compaction without contaminating binders or plasticizers.

  2. Highly Dense Isolated Metal Atom Catalytic Sites: Dynamic Formation and In Situ Observations.

    PubMed

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei; Hu, Pingping; Chen, Jianmin; Liu, Xi; Tang, Xingfu

    2015-11-23

    Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X-ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation at low temperature. This work provides a general strategy for designing atomically dispersed noble-metal catalysts with highly dense active sites.

  3. Design of dense transmission diffraction gratings for high efficiency.

    PubMed

    Golub, Michael A

    2015-01-01

    We propose a design method for dense surface-relief diffraction gratings with high efficiency in transmission mode. Closed-form analytical relations between diffraction efficiency, polarization, and grating parameters are derived and verified in the resonance domain of diffraction under general three-dimensional angles of incidence traditionally termed conical mounting. A powerful tool for rigorous design of computer-generated holograms and diffractive optical elements with spectroscopic scale periods is now enabled.

  4. Kinetic Temperatures of the Dense Gas Clumps in the Orion KL Molecular Core

    NASA Technical Reports Server (NTRS)

    Wang, Kuo-Song; Kuan, Yi-Jehng; Liu, Sheng-Yuan; Charnley, Steven B.

    2010-01-01

    High angular-resolution images of the J = 18(sub K)-17(sub K) emission of CH3CN in the Orion KL molecular core were observed with the Submillimeter Array (SMA). Our high-resolution observations clearly reveal that CH3CN emission originates mainly from the Orion Hot Core and the Compact Ridge, both within approximately 15 inches of the warm and dense part of Orion KL. The clumpy nature of the molecular gas in Orion KL can also be readily seen from our high-resolution SMA images. In addition, a semi-open cavity-like kinematic structure is evident at the location between the Hot Core and the Compact Ridge. We performed excitation analysis with the "population diagram" method toward the Hot Core, IRc7, and the northern part of the Compact Ridge. Our results disclose a non-uniform temperature structure on small scales in Orion KL, with a range of temperatures from 190-620 K in the Hot Core. Near the Compact Ridge, the temperatures are found to be 170-280 K. Comparable CH3CN fractional abundances of 10(exp -8) to 10(exp -7) are found around both in the Hot Core and the Compact Ridge. Such high abundances require that a hot gas phase chemistry, probably involving ammonia released from grain mantles, plays an important role in forming these CH3CN molecules.

  5. Measurement of the Electron-Ion Temperature Relaxation Rate in a Dense Plasma

    NASA Astrophysics Data System (ADS)

    Taccetti, J. M.; Shurter, R. P.; Goodwin, P. M.; Benage, J. F., Jr.

    2008-11-01

    Current theoretical approaches to temperature relaxation, which can be categorized as binary-collision and many-body approaches, disagree. Existing experimental evidence infers a lower relaxation rate compared to the binary-collision approach, but is insufficient to determine which approach is correct. We present the most recent results from an experiment aimed at obtaining the temperature relaxation rate between ions and electrons in a dense, strongly coupled plasma by directly measuring the temperature of each component. The plasma is formed by heating a gas jet with a 10 ps laser pulse. The electrons are preferentially heated by the short pulse laser (Te 100 eV), while the ions, after undergoing very rapid (sub-ps time-scale) disorder-induced heating, should only reach a temperature of 10-15 eV. This results in a strongly coupled ion plasma with an ion-ion coupling parameter γii 3-5. We plan to measure the electron and ion temperatures of the resulting plasma independently during and after heating, using collective Thomson scattering for electrons and a high-resolution x-ray spectrometer for the ions (measuring Doppler-broadened absorption lines).

  6. Atoms in dense plasmas

    SciTech Connect

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs.

  7. High frequency flow-structural interaction in dense subsonic fluids

    NASA Technical Reports Server (NTRS)

    Liu, Baw-Lin; Ofarrell, J. M.

    1995-01-01

    Prediction of the detailed dynamic behavior in rocket propellant feed systems and engines and other such high-energy fluid systems requires precise analysis to assure structural performance. Designs sometimes require placement of bluff bodies in a flow passage. Additionally, there are flexibilities in ducts, liners, and piping systems. A design handbook and interactive data base have been developed for assessing flow/structural interactions to be used as a tool in design and development, to evaluate applicable geometries before problems develop, or to eliminate or minimize problems with existing hardware. This is a compilation of analytical/empirical data and techniques to evaluate detailed dynamic characteristics of both the fluid and structures. These techniques have direct applicability to rocket engine internal flow passages, hot gas drive systems, and vehicle propellant feed systems. Organization of the handbook is by basic geometries for estimating Strouhal numbers, added mass effects, mode shapes for various end constraints, critical onset flow conditions, and possible structural response amplitudes. Emphasis is on dense fluids and high structural loading potential for fatigue at low subsonic flow speeds where high-frequency excitations are possible. Avoidance and corrective measure illustrations are presented together with analytical curve fits for predictions compiled from a comprehensive data base.

  8. Characterization of Nano-Crystalline Diamond like Carbon (DLC) Films with Substrate Temperature Using Dense Plasma Focusing Method

    SciTech Connect

    Yadav, Vikram S; Dhubkarya, D. C.; Singh, Yashpal; Sahu, Devendra K; Singh, Manveer; Kumar, Kuldeep

    2010-06-17

    Nano-crystalline Diamond like Carbon (DLC) film has been grown by Dense Plasma Focusing Method (DPF) using pure graphite Plasma, on different substrate (glass/silica) at different substrate temperature. The films were grown at substrate temperature 100 deg. C, 150 deg. C and 300 deg. C by the high dense plasma of energy 1.3 k Joule on glass and silica. Raman spectra confirmed that sp{sup 3} content is grown in the films under various conditions. The Raman spectra of these films show a broad asymmetric peak which narrow with sp{sup 2} decreasing contents. We believe that our data presented here may be used as reference of DLC characterization.

  9. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    DOE PAGES

    Bang, Woosuk; Albright, Brian James; Bradley, Paul Andrew; Vold, Erik Lehman; Boettger, Jonathan Carl; Fernández, Juan Carlos

    2016-07-12

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly withmore » temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. In conclusion, these simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.« less

  10. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    NASA Astrophysics Data System (ADS)

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2016-07-01

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. These simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.

  11. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    PubMed Central

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2016-01-01

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. These simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement. PMID:27405664

  12. High temperature furnace

    DOEpatents

    Borkowski, Casimer J.

    1976-08-03

    A high temperature furnace for use above 2000.degree.C is provided that features fast initial heating and low power consumption at the operating temperature. The cathode is initially heated by joule heating followed by electron emission heating at the operating temperature. The cathode is designed for routine large temperature excursions without being subjected to high thermal stresses. A further characteristic of the device is the elimination of any ceramic components from the high temperature zone of the furnace.

  13. Feasibility study of measuring the temperature and pressure of warm dense matter.

    SciTech Connect

    Rambo, Patrick K.; Schwarz, Jens

    2008-09-01

    We have investigated the feasibility of making accurate measurements of the temperature and pressure of solid-density samples rapidly heated by the Z-Petawatt laser to warm dense matter (WDM) conditions, with temperatures approaching 100eV. The study focused specifically on the heating caused by laser generated proton beams. Based on an extensive literature search and numerical investigations, a WDM experiment is proposed which will accurately measure temperature and pressure based on optical emission from the surface and sample expansion velocity.

  14. Enhancement of Curie temperature of barium hexaferrite by dense electronic excitations

    SciTech Connect

    Sharma, Manju; Kashyap, Subhash C.; Gupta, Hem C.; Dimri, Mukesh C.; Asokan, K.

    2014-07-15

    Curie temperature of polycrystalline barium hexaferrite (BaFe{sub 12}O{sub 19}), prepared by conventional solid state technique, is anomalously and significantly enhanced (by nearly 15%) by energetic heavy ion irradiation (150 MeV, Ag{sup 12+}) at ambient temperature due to dense electronic excitations Moderate fluence (1 × 10{sup 12} ions/cm{sup 2}) induces structural defects giving rise to above enhancement. As established by X-ray diffraction, scanning electron microscopy and Raman studies, higher fluence (1 × 10{sup 13} ions/cm{sup 2}) has structurally transformed the sample to amorphous phase with marginal change in magnetization and Curie temperature.

  15. Lattice thermal conductivity of dense silicate glass at high pressures

    NASA Astrophysics Data System (ADS)

    Chang, Y. Y.; Hsieh, W. P.

    2015-12-01

    The layered structure of the Earth's interior is generally believed to develop through the magma ocean differentiation in the early Earth. Previous seismic studies revealed the existence of ultra low velocity zones above the core mantle boundary (CMB) which was inferred to be associated with the remnant of a deep magma ocean. The heat flux through the core mantle boundary therefore would strongly depend on the thermal conductivity, both lattice (klat) and radiative (krad) of dense silicate melts and major constituent minerals of the lower mantle. Recent experimental results on the radiative thermal conductivity of dense silicate glasses and lower-mantle minerals suggest that krad of dense silicate glasses could be remarkably lower than krad of the surrounding solid mantle phases. In this case, the dense silicate melts will act as a trap for heat from the Earth's outer core. However, this conclusion remains uncertain because of the lack of direct measurements on lattice thermal conductivities of silicate glasses/melts under lower mantle pressures up to date. Here we report experimental results on lattice thermal conductivities of dense silicate glass with basaltic composition under pressures relevant to the Earth's lower mantle in a diamond-anvil cell using time-domain thermoreflectance method. The study will assist the comprehension of thermal transport properties of silicate melts in the Earth's deep interior and is crucial for understanding the dynamic and thermal evolution of the Earth's internal structure.

  16. High temperature reactors

    NASA Astrophysics Data System (ADS)

    Dulera, I. V.; Sinha, R. K.

    2008-12-01

    With the advent of high temperature reactors, nuclear energy, in addition to producing electricity, has shown enormous potential for the production of alternate transport energy carrier such as hydrogen. High efficiency hydrogen production processes need process heat at temperatures around 1173-1223 K. Bhabha Atomic Research Centre (BARC), is currently developing concepts of high temperature reactors capable of supplying process heat around 1273 K. These reactors would provide energy to facilitate combined production of hydrogen, electricity, and drinking water. Compact high temperature reactor is being developed as a technology demonstrator for associated technologies. Design has been also initiated for a 600 MWth innovative high temperature reactor. High temperature reactor development programme has opened new avenues for research in areas like advanced nuclear fuels, high temperature and corrosion resistant materials and protective coatings, heavy liquid metal coolant technologies, etc. The paper highlights design of these reactors and their material related requirements.

  17. High temperature sensor

    DOEpatents

    Tokarz, Richard D.

    1982-01-01

    A high temperature sensor includes a pair of electrical conductors separated by a mass of electrical insulating material. The insulating material has a measurable resistivity within the sensor that changes in relation to the temperature of the insulating material within a high temperature range (1,000 to 2,000 K.). When required, the sensor can be encased within a ceramic protective coating.

  18. High Temperature Akali Corrosion of Dense SiC and Si(3)N(4) Coated with CMZP and Mg-Doped Al(2)TiO(5) in Coal Gas

    SciTech Connect

    Thierry, N.; Brown, J.J.

    1997-04-15

    Si{sub 3}N{sub 4} ceramics possess properties that are attractive for high temperature heat exchanger applications. These properties include high strength, good thermal conductivity and excellent resistance to thermal shock and oxidation. However when subjected to alkaline containing environments, Si{sub 3}N{sub 4} is prone to corrode and eventually loses its properties. Because it was found that oxide ceramics corrode substantially less, they can be used as a coating to protect Si{sub 3}N{sub 4}. Therefore the first objective of this work is to develop thin film of CMZP and Mg-doped Al{sub 2}TiO{sub 5} since both of them are good candidate coating materials of primary interest for the protection of Si{sub 3}N{sub 4} against alkaline corrosion.

  19. High-Temperature Superconductivity

    NASA Astrophysics Data System (ADS)

    Tanaka, Shoji

    2006-12-01

    A general review on high-temperature superconductivity was made. After prehistoric view and the process of discovery were stated, the special features of high-temperature superconductors were explained from the materials side and the physical properties side. The present status on applications of high-temperature superconductors were explained on superconducting tapes, electric power cables, magnets for maglev trains, electric motors, superconducting quantum interference device (SQUID) and single flux quantum (SFQ) devices and circuits.

  20. High temperature refrigerator

    DOEpatents

    Steyert, Jr., William A.

    1978-01-01

    A high temperature magnetic refrigerator which uses a Stirling-like cycle in which rotating magnetic working material is heated in zero field and adiabatically magnetized, cooled in high field, then adiabatically demagnetized. During this cycle said working material is in heat exchange with a pumped fluid which absorbs heat from a low temperature heat source and deposits heat in a high temperature reservoir. The magnetic refrigeration cycle operates at an efficiency 70% of Carnot.

  1. High temperature measuring device

    DOEpatents

    Tokarz, Richard D.

    1983-01-01

    A temperature measuring device for very high design temperatures (to 2,000.degree. C.). The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensionally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.

  2. High-temperature sensor

    DOEpatents

    Not Available

    1981-01-29

    A high temperature sensor is described which includes a pair of electrical conductors separated by a mass of electrical insulating material. The insulating material has a measurable resistivity within the sensor that changes in relation to the temperature of the insulating material within a high temperature range (1000 to 2000/sup 0/K). When required, the sensor can be encased within a ceramic protective coating.

  3. Fast and accurate quantum molecular dynamics of dense plasmas across temperature regimes

    DOE PAGES

    Sjostrom, Travis; Daligault, Jerome

    2014-10-10

    Here, we develop and implement a new quantum molecular dynamics approximation that allows fast and accurate simulations of dense plasmas from cold to hot conditions. The method is based on a carefully designed orbital-free implementation of density functional theory. The results for hydrogen and aluminum are in very good agreement with Kohn-Sham (orbital-based) density functional theory and path integral Monte Carlo calculations for microscopic features such as the electron density as well as the equation of state. The present approach does not scale with temperature and hence extends to higher temperatures than is accessible in the Kohn-Sham method and lowermore » temperatures than is accessible by path integral Monte Carlo calculations, while being significantly less computationally expensive than either of those two methods.« less

  4. Fast and accurate quantum molecular dynamics of dense plasmas across temperature regimes

    SciTech Connect

    Sjostrom, Travis; Daligault, Jerome

    2014-10-10

    Here, we develop and implement a new quantum molecular dynamics approximation that allows fast and accurate simulations of dense plasmas from cold to hot conditions. The method is based on a carefully designed orbital-free implementation of density functional theory. The results for hydrogen and aluminum are in very good agreement with Kohn-Sham (orbital-based) density functional theory and path integral Monte Carlo calculations for microscopic features such as the electron density as well as the equation of state. The present approach does not scale with temperature and hence extends to higher temperatures than is accessible in the Kohn-Sham method and lower temperatures than is accessible by path integral Monte Carlo calculations, while being significantly less computationally expensive than either of those two methods.

  5. Temperature and density dependence of XANES spectra in warm dense aluminum plasmas

    NASA Astrophysics Data System (ADS)

    Recoules, V.; Mazevet, S.

    2009-08-01

    Using ab initio molecular-dynamics simulations combined with linear-response theory, we calculate the density and temperature dependence of the x-ray absorption near-edge structure (XANES) of a dense aluminum plasma. At solid density and for temperatures increasing up to 6 eV, we see that the XANES spectrum loses its well-known room-temperature structure, first due to melting and second due to loss of correlation in the liquid. Similarly, as the density decreases and the system evolves from a liquid to a plasma, the XANES spectrum becomes less structured. As the density is further lowered and the system turns into an atomic fluid, a pre-edge forms as the 3p state becomes bound. We suggest that direct measurements of the XANES spectra in this density region is a unique opportunity to validate pressure ionization models routinely used in plasma physics modeling.

  6. River Inflows into Lakes: Basin Temperature Profiles Driven By Peeling Detrainment from Dense Underflows

    NASA Astrophysics Data System (ADS)

    Hogg, C. A. R.; Huppert, H. E.; Imberger, J.; Dalziel, S. B.

    2014-12-01

    Dense gravity currents from river inflows feed fluid into confined basins in lakes. Large inflows can influence temperature profiles in the basins. Existing parameterisations of the circulation and mixing of such inflows are often based on the entrainment of ambient fluid into the underflowing gravity currents. However, recent observations have suggested that uni-directional entrainment into a gravity current does not fully describe the transfer between such gravity currents and the ambient water. Laboratory experiments visualised peeling detrainment from the gravity current occurring when the ambient fluid was stratified. A theoretical model of the observed peeling detrainment was developed to predict the temperature profile in the basin. This new model gives a better approximation of the temperature profile observed in the experiments than the pre-existing entraining model. The model can now be developed such that it integrates into operational models of lake basins.

  7. High Temperature Alkali Corrosion of Dense SiC and Si(3)N(4) Coated with CMZP and Mg-Doped Al(2) TiO(5) in Coal Gas.

    SciTech Connect

    Thieny, N.; Brown, J.J.

    1997-07-01

    Hot pressed Si{sub 3}N{sub 4} has been extensively studied in the past years mainly because it is a potential candidate for high temperature structural applications. If its behavior in alkaline environments has been widely investigated and is now well understood, only a few authors have conducted research on thin film to enhance Si{sub 3}N{sub 4} lifetime in harsh environments. Thus, it is the first objective of this work to develop thin film of CMZP and Mg doped Al{sub 2}TiO{sub 5} using the sol-gel process and the dip coating technique. In the previous report relatively good coverage of the substrate surface was achieved with low concentration solutions and double coatings. However, the aggregation of the sol-gel at the bottom of some samples suggested that more viscous sol-gels, i.e. higher concentrations, could alleviate this phenomenon. This report will therefore present the results obtained with more concentrated solutions and also those obtained with two other CMZP solutions utilizing different precursors.

  8. High contrast radiography using a small dense plasma focus

    SciTech Connect

    Castillo, F.; Gamboa-deBuen, I.; Herrera, J. J. E.; Rangel, J.; Villalobos, S.

    2008-02-04

    Radiographs are obtained with a small (4.6 kJ) dense plasma focus machine, using the x-rays which cross a 300 {mu}m aluminum window on the axis. Contrast is improved by inserting an iron needle on the tip of the electrode. Measurements with TLD-100 dosimeters have shown the average dose to increase from 0.077{+-}0.006 mGy/shot, when a hollow cathode is used, to 0.11{+-}0.01 mGy/shot, with the needle. The spectrum is estimated using aluminum filters and the effective equivalent energy is found to be in the range of 20-25 keV.

  9. High-Temperature Superconductivity

    SciTech Connect

    Peter Johnson

    2008-11-05

    Like astronomers tweaking images to gain a more detailed glimpse of distant stars, physicists at Brookhaven National Laboratory have found ways to sharpen images of the energy spectra in high-temperature superconductors — materials that carry electrical c

  10. High Temperature Capacitor Development

    SciTech Connect

    John Kosek

    2009-06-30

    The absence of high-temperature electronics is an obstacle to the development of untapped energy resources (deep oil, gas and geothermal). US natural gas consumption is projected to grow from 22 trillion cubic feet per year (tcf) in 1999 to 34 tcf in 2020. Cumulatively this is 607 tcf of consumption by 2020, while recoverable reserves using current technology are 177 tcf. A significant portion of this shortfall may be met by tapping deep gas reservoirs. Tapping these reservoirs represents a significant technical challenge. At these depths, temperatures and pressures are very high and may require penetrating very hard rock. Logistics of supporting 6.1 km (20,000 ft) drill strings and the drilling processes are complex and expensive. At these depths up to 50% of the total drilling cost may be in the last 10% of the well depth. Thus, as wells go deeper it is increasingly important that drillers are able to monitor conditions down-hole such as temperature, pressure, heading, etc. Commercial off-the-shelf electronics are not specified to meet these operating conditions. This is due to problems associated with all aspects of the electronics including the resistors and capacitors. With respect to capacitors, increasing temperature often significantly changes capacitance because of the strong temperature dependence of the dielectric constant. Higher temperatures also affect the equivalent series resistance (ESR). High-temperature capacitors usually have low capacitance values because of these dielectric effects and because packages are kept small to prevent mechanical breakage caused by thermal stresses. Electrolytic capacitors do not operate at temperatures above 150oC due to dielectric breakdown. The development of high-temperature capacitors to be used in a high-pressure high-temperature (HPHT) drilling environment was investigated. These capacitors were based on a previously developed high-voltage hybridized capacitor developed at Giner, Inc. in conjunction with a

  11. High temperature pressure gauge

    DOEpatents

    Echtler, J. Paul; Scandrol, Roy O.

    1981-01-01

    A high temperature pressure gauge comprising a pressure gauge positioned in fluid communication with one end of a conduit which has a diaphragm mounted in its other end. The conduit is filled with a low melting metal alloy above the diaphragm for a portion of its length with a high temperature fluid being positioned in the remaining length of the conduit and in the pressure gauge.

  12. High-temperature electronics

    NASA Technical Reports Server (NTRS)

    Matus, Lawrence G.; Seng, Gary T.

    1990-01-01

    To meet the needs of the aerospace propulsion and space power communities, the high temperature electronics program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. This program supports a major element of the Center's mission - to perform basic and developmental research aimed at improving aerospace propulsion systems. Research is focused on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of SiC devices.

  13. High Temperature ESP Monitoring

    SciTech Connect

    Jack Booker; Brindesh Dhruva

    2011-06-20

    The objective of the High Temperature ESP Monitoring project was to develop a downhole monitoring system to be used in wells with bottom hole well temperatures up to 300°C for measuring motor temperature, formation pressure, and formation temperature. These measurements are used to monitor the health of the ESP motor, to track the downhole operating conditions, and to optimize the pump operation. A 220 ºC based High Temperature ESP Monitoring system was commercially released for sale with Schlumberger ESP motors April of 2011 and a 250 ºC system with will be commercially released at the end of Q2 2011. The measurement system is now fully qualified, except for the sensor, at 300 °C.

  14. High temperature probe

    DOEpatents

    Swan, Raymond A.

    1994-01-01

    A high temperature probe for sampling, for example, smokestack fumes, and is able to withstand temperatures of 3000.degree. F. The probe is constructed so as to prevent leakage via the seal by placing the seal inside the water jacket whereby the seal is not exposed to high temperature, which destroys the seal. The sample inlet of the probe is also provided with cooling fins about the area of the seal to provide additional cooling to prevent the seal from being destroyed. Also, a heated jacket is provided for maintaining the temperature of the gas being tested as it passes through the probe. The probe includes pressure sensing means for determining the flow velocity of an efficient being sampled. In addition, thermocouples are located in various places on the probe to monitor the temperature of the gas passing there through.

  15. High temperature structural silicides

    SciTech Connect

    Petrovic, J.J.

    1997-03-01

    Structural silicides have important high temperature applications in oxidizing and aggressive environments. Most prominent are MoSi{sub 2}-based materials, which are borderline ceramic-intermetallic compounds. MoSi{sub 2} single crystals exhibit macroscopic compressive ductility at temperatures below room temperature in some orientations. Polycrystalline MoSi{sub 2} possesses elevated temperature creep behavior which is highly sensitive to grain size. MoSi{sub 2}-Si{sub 3}N{sub 4} composites show an important combination of oxidation resistance, creep resistance, and low temperature fracture toughness. Current potential applications of MoSi{sub 2}-based materials include furnace heating elements, molten metal lances, industrial gas burners, aerospace turbine engine components, diesel engine glow plugs, and materials for glass processing.

  16. Characterization of warm dense matter (WDM) from high intensity laser driven shockwaves

    NASA Astrophysics Data System (ADS)

    Krauland, Christine; Wei, Mingsheng; Santos, Joao; Belancourt, Patrick; Theobald, Wolfgang; Keiter, Paul; Beg, Farhat

    2015-11-01

    Understanding the transport physics of an intense relativistic electron beam in various plasma regimes is crucial for many high-energy-density applications, such as fast heating for advanced ICF schemes and ion sources. Most short pulse laser-matter interaction experiments for electron transport studies have been performed with initially cold targets where the resistivity is far from that in warm dense and hot dense plasmas. In order to extend fast electron transport and energy coupling studies in pre-assembled plasmas, we must first characterize those regime possibilities. We present initial experiments conducted on the OMEGA EP laser (~ 1014 W/cm2) to characterize WDM created from the shock compression of low density (ρ0 ~ 330 mg/cc) CRF foams and solid Al foil targets. In foam targets, imaging x-ray Thomson scattering is used to measure spatial profiles of the temperature, ionization state and relative material density. The ASBO diagnostic and radiation hydrodynamics simulations deduce shock pressure in Al targets of various thicknesses. Details of the experiment and available data will be presented. The work was funded by the US DOE/NNSA NLUF Program.

  17. High Temperature Piezoelectric Drill

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Scott, James; Boudreau, Kate; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom; Zhang, Shujun

    2009-01-01

    The current NASA Decadal mission planning effort has identified Venus as a significant scientific target for a surface in-situ sampling/analyzing mission. The Venus environment represents several extremes including high temperature (460 deg C), high pressure (9 MPa), and potentially corrosive (condensed sulfuric acid droplets that adhere to surfaces during entry) environments. This technology challenge requires new rock sampling tools for these extreme conditions. Piezoelectric materials can potentially operate over a wide temperature range. Single crystals, like LiNbO3, have a Curie temperature that is higher than 1000 deg C and the piezoelectric ceramics Bismuth Titanate higher than 600 deg C. A study of the feasibility of producing piezoelectric drills that can operate in the temperature range up to 500 deg C was conducted. The study includes the high temperature properties investigations of engineering materials and piezoelectric ceramics with different formulas and doping. The drilling performances of a prototype Ultrasonic/Sonic Drill/Corer (USDC) using high temperate piezoelectric ceramics and single crystal were tested at temperature up to 500 deg C. The detailed results of our study and a discussion of the future work on performance improvements are presented in this paper.

  18. Dense dislocation arrays embedded in grain boundaries for high-performance bulk thermoelectrics

    NASA Astrophysics Data System (ADS)

    Kim, Sang Il; Lee, Kyu Hyoung; Mun, Hyeon A.; Kim, Hyun Sik; Hwang, Sung Woo; Roh, Jong Wook; Yang, Dae Jin; Shin, Weon Ho; Li, Xiang Shu; Lee, Young Hee; Snyder, G. Jeffrey; Kim, Sung Wng

    2015-04-01

    The widespread use of thermoelectric technology is constrained by a relatively low conversion efficiency of the bulk alloys, which is evaluated in terms of a dimensionless figure of merit (zT). The zT of bulk alloys can be improved by reducing lattice thermal conductivity through grain boundary and point-defect scattering, which target low- and high-frequency phonons. Dense dislocation arrays formed at low-energy grain boundaries by liquid-phase compaction in Bi0.5Sb1.5Te3 (bismuth antimony telluride) effectively scatter midfrequency phonons, leading to a substantially lower lattice thermal conductivity. Full-spectrum phonon scattering with minimal charge-carrier scattering dramatically improved the zT to 1.86 ± 0.15 at 320 kelvin (K). Further, a thermoelectric cooler confirmed the performance with a maximum temperature difference of 81 K, which is much higher than current commercial Peltier cooling devices.

  19. Thermoelectrics. Dense dislocation arrays embedded in grain boundaries for high-performance bulk thermoelectrics.

    PubMed

    Kim, Sang Il; Lee, Kyu Hyoung; Mun, Hyeon A; Kim, Hyun Sik; Hwang, Sung Woo; Roh, Jong Wook; Yang, Dae Jin; Shin, Weon Ho; Li, Xiang Shu; Lee, Young Hee; Snyder, G Jeffrey; Kim, Sung Wng

    2015-04-01

    The widespread use of thermoelectric technology is constrained by a relatively low conversion efficiency of the bulk alloys, which is evaluated in terms of a dimensionless figure of merit (zT). The zT of bulk alloys can be improved by reducing lattice thermal conductivity through grain boundary and point-defect scattering, which target low- and high-frequency phonons. Dense dislocation arrays formed at low-energy grain boundaries by liquid-phase compaction in Bi(0.5)Sb(1.5)Te3 (bismuth antimony telluride) effectively scatter midfrequency phonons, leading to a substantially lower lattice thermal conductivity. Full-spectrum phonon scattering with minimal charge-carrier scattering dramatically improved the zT to 1.86 ± 0.15 at 320 kelvin (K). Further, a thermoelectric cooler confirmed the performance with a maximum temperature difference of 81 K, which is much higher than current commercial Peltier cooling devices. PMID:25838382

  20. Thermoelectrics. Dense dislocation arrays embedded in grain boundaries for high-performance bulk thermoelectrics.

    PubMed

    Kim, Sang Il; Lee, Kyu Hyoung; Mun, Hyeon A; Kim, Hyun Sik; Hwang, Sung Woo; Roh, Jong Wook; Yang, Dae Jin; Shin, Weon Ho; Li, Xiang Shu; Lee, Young Hee; Snyder, G Jeffrey; Kim, Sung Wng

    2015-04-01

    The widespread use of thermoelectric technology is constrained by a relatively low conversion efficiency of the bulk alloys, which is evaluated in terms of a dimensionless figure of merit (zT). The zT of bulk alloys can be improved by reducing lattice thermal conductivity through grain boundary and point-defect scattering, which target low- and high-frequency phonons. Dense dislocation arrays formed at low-energy grain boundaries by liquid-phase compaction in Bi(0.5)Sb(1.5)Te3 (bismuth antimony telluride) effectively scatter midfrequency phonons, leading to a substantially lower lattice thermal conductivity. Full-spectrum phonon scattering with minimal charge-carrier scattering dramatically improved the zT to 1.86 ± 0.15 at 320 kelvin (K). Further, a thermoelectric cooler confirmed the performance with a maximum temperature difference of 81 K, which is much higher than current commercial Peltier cooling devices.

  1. Measuring the Ion Temperature in X-ray Thomson Scattering Experiments of Warm Dense Matter (WDM)

    NASA Astrophysics Data System (ADS)

    Benage, John; Murillo, Michael

    2010-11-01

    X-ray Thomson scattering offers an unprecedented method for measuring the properties of dense plasmas, including the electron temperature, the ionization state, and the free electron density. More difficult to extract from the measurements is the ion temperature. To date, the ion temperature has been extracted from experimental data using the diffractive portion of the scattering signal, which is a measure of the ion static structure S(k); thus, an accurate measurement requires an accurate model for S(k). Here, we compare models for S(k) in WDM and find that their differences are significant. Because of the paucity of WDM data, we use very accurate liquid metal data as a proxy. No current model reproduces all of the liquid metal data, although some are better for certain metals than others. We also introduce a new model that employs an effective screening length, obtained from the finite-temperature Lindhard response, in a modified hypernetted chain approach. This approach is superior to the previous approaches and we expect it will be even better for WDM.

  2. The Benefits of Using Dense Temperature Sensor Networks to Monitor Urban Warming

    NASA Astrophysics Data System (ADS)

    Twine, T. E.; Snyder, P. K.; Kucharik, C. J.; Schatz, J.

    2015-12-01

    Urban heat islands (UHIs) occur when urban and suburban areas experience temperatures that are elevated relative to their rural surroundings because of differences in the fraction of gray and green infrastructure. Studies have shown that communities most at risk for impacts from climate-related disasters (i.e., lower median incomes, higher poverty, lower education, and minorities) tend to live in the hottest areas of cities. Development of adequate climate adaptation tools for cities relies on knowledge of how temperature varies across space and time. Traditionally, a city's urban heat island has been quantified using near-surface air temperature measurements from a few sites. This methodology assumes (1) that the UHI can be characterized by the difference in air temperature from a small number of points, and (2) that these few points represent the urban and rural signatures of the region. This methodology ignores the rich information that could be gained from measurements across the urban to rural transect. This transect could traverse elevations, water bodies, vegetation fraction, and other land surface properties. Two temperature sensor networks were designed and implemented in the Minneapolis-Saint Paul, MN and Madison, WI metropolitan areas beginning in 2011 and 2012, respectively. Both networks use the same model sensor and record temperature every 15 minutes from ~150 sensors. Data from each network has produced new knowledge of how temperature varies diurnally and seasonally across the cities and how the UHI magnitude is influenced by weather phenomena (e.g., wind, snow cover, heat waves) and land surface characteristics such as proximity to inland lakes. However, the two metropolitan areas differ in size, population, structure, and orientation to water bodies. In addition, the sensor networks were established in very different manners. We describe these differences and present lessons learned from the design and ongoing efforts of these two dense networks

  3. High temperature storage loop :

    SciTech Connect

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  4. High Temperature Structural Foam

    NASA Technical Reports Server (NTRS)

    Weiser, Erik S.; Baillif, Faye F.; Grimsley, Brian W.; Marchello, Joseph M.

    1997-01-01

    The Aerospace Industry is experiencing growing demand for high performance polymer foam. The X-33 program needs structural foam insulation capable of retaining its strength over a wide range of environmental conditions. The High Speed Research Program has a need for low density core splice and potting materials. This paper reviews the state of the art in foam materials and describes experimental work to fabricate low density, high shear strength foam which can withstand temperatures from -220 C to 220 C. Commercially available polymer foams exhibit a wide range of physical properties. Some with densities as low as 0.066 g/cc are capable of co-curing at temperatures as high as 182 C. Rohacell foams can be resin transfer molded at temperatures up to 180 C. They have moduli of elasticity of 0.19 MPa, tensile strengths of 3.7 Mpa and compressive strengths of 3.6 MPa. The Rohacell foams cannot withstand liquid hydrogen temperatures, however Imi-Tech markets Solimide (trademark) foams which withstand temperatures from -250 C to 200 C, but they do not have the required structural integrity. The research activity at NASA Langley Research Center focuses on using chemical blowing agents to produce polyimide thermoplastic foams capable of meeting the above performance requirements. The combination of blowing agents that decompose at the minimum melt viscosity temperature together with plasticizers to lower the viscosity has been used to produce foams by both extrusion and oven heating. The foams produced exhibit good environmental stability while maintaining structural properties.

  5. High-Temperature Superconductivity

    ScienceCinema

    Peter Johnson

    2016-07-12

    Like astronomers tweaking images to gain a more detailed glimpse of distant stars, physicists at Brookhaven National Laboratory have found ways to sharpen images of the energy spectra in high-temperature superconductors — materials that carry electrical c

  6. HIGH TEMPERATURE THERMOCOUPLE

    DOEpatents

    Eshayu, A.M.

    1963-02-12

    This invention contemplates a high temperature thermocouple for use in an inert or a reducing atmosphere. The thermocouple limbs are made of rhenium and graphite and these limbs are connected at their hot ends in compressed removable contact. The rhenium and graphite are of high purity and are substantially stable and free from diffusion into each other even without shielding. Also, the graphite may be thick enough to support the thermocouple in a gas stream. (AEC)

  7. Detonation performance of high-dense BTF charges

    NASA Astrophysics Data System (ADS)

    Dolgoborodov, Alexander; Brazhnikov, Michael; Makhov, Michael; Gubin, Sergey; Maklasova, Irina

    2013-06-01

    New experimental data on detonation wave parameters and explosive performance for benzotrifuroxan (BTF) are presented. Optical pyrometry was applied in order to measure the temperature and pressure of BTF detonation products. Chapman-Jouguet pressure and temperature were obtained as following: 33.8 GPa and 3990 K; 34.5 GPa and 4170 K (initial charge densities 1.82 and 1.84 g/cc respectively), the polytropic exponent was estimated as 2.8. The heat of explosion and acceleration ability were measured also. The results of calorimetric measurements performed in bomb calorimeter indicate that BTF slightly surpasses HMX in the heat of explosion. However BTF is inferior to HMX in the acceleration ability, measured by the method of copper casing expansion. It is also considered the hypothesis of formation of nanocarbon particles in detonation products directly behind the detonation front and influence of this processes on the temperature-time history in detonation products. The results of calculations with in view of formation of liquid nanocarbon in products of a detonation also are presented.

  8. High temperature thermometric phosphors

    DOEpatents

    Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.y) wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

  9. High temperature thermometric phosphors

    DOEpatents

    Allison, S.W.; Cates, M.R.; Boatner, L.A.; Gillies, G.T.

    1999-03-23

    A high temperature phosphor consists essentially of a material having the general formula LuPO{sub 4}:Dy{sub x},Eu{sub y} wherein: 0.1 wt % {<=} x {<=} 20 wt % and 0.1 wt % {<=} y {<=} 20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopant. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions. 2 figs.

  10. Nanosecond high-power dense microplasma switch for visible light

    SciTech Connect

    Bataller, A. Koulakis, J.; Pree, S.; Putterman, S.

    2014-12-01

    Spark discharges in high-pressure gas are known to emit a broadband spectrum during the first 10 s of nanoseconds. We present calibrated spectra of high-pressure discharges in xenon and show that the resulting plasma is optically thick. Laser transmission data show that such a body is opaque to visible light, as expected from Kirchoff's law of thermal radiation. Nanosecond framing images of the spark absorbing high-power laser light are presented. The sparks are ideal candidates for nanosecond, high-power laser switches.

  11. Nanosecond high-power dense microplasma switch for visible light

    NASA Astrophysics Data System (ADS)

    Bataller, A.; Koulakis, J.; Pree, S.; Putterman, S.

    2014-12-01

    Spark discharges in high-pressure gas are known to emit a broadband spectrum during the first 10 s of nanoseconds. We present calibrated spectra of high-pressure discharges in xenon and show that the resulting plasma is optically thick. Laser transmission data show that such a body is opaque to visible light, as expected from Kirchoff's law of thermal radiation. Nanosecond framing images of the spark absorbing high-power laser light are presented. The sparks are ideal candidates for nanosecond, high-power laser switches.

  12. Carbon Dioxide Clouds at High Altitude in the Tropics and in an Early Dense Martian Atmosphere

    NASA Technical Reports Server (NTRS)

    Colaprete, Anthony; Toon, Owen B.

    2001-01-01

    We use a time dependent, microphysical cloud model to study the formation of carbon dioxide clouds in the Martian atmosphere. Laboratory studies by Glandor et al. show that high critical supersaturations are required for cloud particle nucleation and that surface kinetic growth is not limited. These conditions, which are similar to those for cirrus clouds on Earth, lead to the formation of carbon dioxide ice particles with radii greater than 500 micrometers and concentrations of less than 0.1 cm(exp -3) for typical atmospheric conditions. Within the current Martian atmosphere, CO2 cloud formation is possible at the poles during winter and at high altitudes in the tropics during periods of increased atmospheric dust loading. In both cases, temperature perturbations of several degrees below the CO2 saturation temperature are required to nucleate new cloud particles suggesting that dynamical processes are the most common initiators of carbon dioxide clouds rather than diabatic cooling. The microphysical cloud model, coupled to a two-stream radiative transfer model, is used to reexamine the impact of CO2 clouds on the surface temperature within a dense CO2 atmosphere. The formation of carbon dioxide clouds leads to a warmer surface than what would be expected for clear sky conditions. The amount of warming is sensitive to the presence of dust and water vapor in the atmosphere, both of which act to dampen cloud effects. The radiative warming associated with cloud formation, as well as latent heating, work to dissipate the clouds when present. Thus, clouds never last for periods much longer than several days, limiting their overall effectiveness for warming the surface. The time average cloud optical depth is approximately unity leading to a 5-10 K warming, depending on the surface pressure. However, the surface temperature does not rise about the freezing point of liquid water even for pressures as high as 5 bars, at a solar luminosity of 75% the current value.

  13. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-12-31

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with super-heated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200{degrees}C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220{degrees}C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: (1) At relative pressures over 0.6 the capillarity forces are very important. (2) There is no significant temperature effect. (3) Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. (4) Pores smaller than 15 {Angstrom} do not contribute to the adsorbed mass.

  14. High temperature adsorption measurements

    SciTech Connect

    Bertani, R.; Parisi, L.; Perini, R.; Tarquini, B.

    1996-01-24

    Adsorption phenomena are a rich and rather new field of study in geothermal research, in particular at very high temperature. ENEL is interested in the exploitation of geothermal regions with superheated steam, and it is important to understand the behavior of water-rock interaction. We have analyzed in the 170-200 °C temperature range four samples of Monteverdi cuttings; the next experimental effort will be at 220 °C and over in 1996. The first results of the 1995 runs are collected in this paper. We can highlight four main items: 1. At relative pressures over 0.6 the capillarity forces are very important. 2. There is no significant temperature effect. 3. Adsorbed water can be present, and it is able to multiply by a factor of 15 the estimated reserve of super-heated steam only. 4. Pores smaller than 15 Å do not contribute to the adsorbed mass.

  15. Importance of finite-temperature exchange correlation for warm dense matter calculations.

    PubMed

    Karasiev, Valentin V; Calderín, Lázaro; Trickey, S B

    2016-06-01

    The effects of an explicit temperature dependence in the exchange correlation (XC) free-energy functional upon calculated properties of matter in the warm dense regime are investigated. The comparison is between the Karasiev-Sjostrom-Dufty-Trickey (KSDT) finite-temperature local-density approximation (TLDA) XC functional [Karasiev et al., Phys. Rev. Lett. 112, 076403 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.076403] parametrized from restricted path-integral Monte Carlo data on the homogeneous electron gas (HEG) and the conventional Monte Carlo parametrization ground-state LDA XC [Perdew-Zunger (PZ)] functional evaluated with T-dependent densities. Both Kohn-Sham (KS) and orbital-free density-functional theories are used, depending upon computational resource demands. Compared to the PZ functional, the KSDT functional generally lowers the dc electrical conductivity of low-density Al, yielding improved agreement with experiment. The greatest lowering is about 15% for T=15 kK. Correspondingly, the KS band structure of low-density fcc Al from the KSDT functional exhibits a clear increase in interband separation above the Fermi level compared to the PZ bands. In some density-temperature regimes, the deuterium equations of state obtained from the two XC functionals exhibit pressure differences as large as 4% and a 6% range of differences. However, the hydrogen principal Hugoniot is insensitive to the explicit XC T dependence because of cancellation between the energy and pressure-volume work difference terms in the Rankine-Hugoniot equation. Finally, the temperature at which the HEG becomes unstable is T≥7200 K for the T-dependent XC, a result that the ground-state XC underestimates by about 1000 K.

  16. Low-temperature catalyst activator: mechanism of dense carbon nanotube forest growth studied using synchrotron radiation

    PubMed Central

    Takashima, Akito; Izumi, Yudai; Ikenaga, Eiji; Ohkochi, Takuo; Kotsugi, Masato; Matsushita, Tomohiro; Muro, Takayuki; Kawabata, Akio; Murakami, Tomo; Nihei, Mizuhisa; Yokoyama, Naoki

    2014-01-01

    The mechanism of the one-order-of-magnitude increase in the density of vertically aligned carbon nanotubes (CNTs) achieved by a recently developed thermal chemical vapor deposition process was studied using synchrotron radiation spectroscopic techniques. In the developed process, a Ti film is used as the underlayer for an Fe catalyst film. A characteristic point of this process is that C2H2 feeding for the catalyst starts at a low temperature of 450°C, whereas conventional feeding temperatures are ∼800°C. Photoemission spectroscopy using soft and hard X-rays revealed that the Ti underlayer reduced the initially oxidized Fe layer at 450°C. A photoemission intensity analysis also suggested that the oxidized Ti layer at 450°C behaved as a support for nanoparticle formation of the reduced Fe, which is required for dense CNT growth. In fact, a CNT growth experiment, where the catalyst chemical state was monitored in situ by X-ray absorption spectroscopy, showed that the reduced Fe yielded a CNT forest at 450°C. Contrarily, an Fe layer without the Ti underlayer did not yield such a CNT forest at 450°C. Photoemission electron microscopy showed that catalyst annealing at the conventional feeding temperature of 800°C caused excess catalyst agglomeration, which should lead to sparse CNTs. In conclusion, in the developed growth process, the low-temperature catalyst activation by the Ti underlayer before the excess Fe agglomeration realised the CNT densification. PMID:25075343

  17. Importance of finite-temperature exchange correlation for warm dense matter calculations

    NASA Astrophysics Data System (ADS)

    Karasiev, Valentin V.; Calderín, Lázaro; Trickey, S. B.

    2016-06-01

    The effects of an explicit temperature dependence in the exchange correlation (XC) free-energy functional upon calculated properties of matter in the warm dense regime are investigated. The comparison is between the Karasiev-Sjostrom-Dufty-Trickey (KSDT) finite-temperature local-density approximation (TLDA) XC functional [Karasiev et al., Phys. Rev. Lett. 112, 076403 (2014), 10.1103/PhysRevLett.112.076403] parametrized from restricted path-integral Monte Carlo data on the homogeneous electron gas (HEG) and the conventional Monte Carlo parametrization ground-state LDA XC [Perdew-Zunger (PZ)] functional evaluated with T -dependent densities. Both Kohn-Sham (KS) and orbital-free density-functional theories are used, depending upon computational resource demands. Compared to the PZ functional, the KSDT functional generally lowers the dc electrical conductivity of low-density Al, yielding improved agreement with experiment. The greatest lowering is about 15% for T =15 kK. Correspondingly, the KS band structure of low-density fcc Al from the KSDT functional exhibits a clear increase in interband separation above the Fermi level compared to the PZ bands. In some density-temperature regimes, the deuterium equations of state obtained from the two XC functionals exhibit pressure differences as large as 4% and a 6% range of differences. However, the hydrogen principal Hugoniot is insensitive to the explicit XC T dependence because of cancellation between the energy and pressure-volume work difference terms in the Rankine-Hugoniot equation. Finally, the temperature at which the HEG becomes unstable is T ≥7200 K for the T -dependent XC, a result that the ground-state XC underestimates by about 1000 K.

  18. Importance of finite-temperature exchange correlation for warm dense matter calculations.

    PubMed

    Karasiev, Valentin V; Calderín, Lázaro; Trickey, S B

    2016-06-01

    The effects of an explicit temperature dependence in the exchange correlation (XC) free-energy functional upon calculated properties of matter in the warm dense regime are investigated. The comparison is between the Karasiev-Sjostrom-Dufty-Trickey (KSDT) finite-temperature local-density approximation (TLDA) XC functional [Karasiev et al., Phys. Rev. Lett. 112, 076403 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.076403] parametrized from restricted path-integral Monte Carlo data on the homogeneous electron gas (HEG) and the conventional Monte Carlo parametrization ground-state LDA XC [Perdew-Zunger (PZ)] functional evaluated with T-dependent densities. Both Kohn-Sham (KS) and orbital-free density-functional theories are used, depending upon computational resource demands. Compared to the PZ functional, the KSDT functional generally lowers the dc electrical conductivity of low-density Al, yielding improved agreement with experiment. The greatest lowering is about 15% for T=15 kK. Correspondingly, the KS band structure of low-density fcc Al from the KSDT functional exhibits a clear increase in interband separation above the Fermi level compared to the PZ bands. In some density-temperature regimes, the deuterium equations of state obtained from the two XC functionals exhibit pressure differences as large as 4% and a 6% range of differences. However, the hydrogen principal Hugoniot is insensitive to the explicit XC T dependence because of cancellation between the energy and pressure-volume work difference terms in the Rankine-Hugoniot equation. Finally, the temperature at which the HEG becomes unstable is T≥7200 K for the T-dependent XC, a result that the ground-state XC underestimates by about 1000 K. PMID:27415377

  19. High Temperature Thermosets

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.

    1999-01-01

    A thermoset or network polymer is an organic material where the molecules are tied together through chemical bonds (crosslinks) and therefore they cannot move past one another. As a result, these materials exhibit a certain degree of dimensional stability. The chemical composition and the degree of crosslink density of the thermoset have a pronounced effect upon the properties. High temperature thermosets offer a favorable combination of properties that makes them attractive for many applications. Their most important features are the excellent processability particularly of the low molecular weight precusor forms, the chemical and solvent resistance and the dimensional stability. The market for high temperature thermosets will increase as new uses for them are uncovered and new thermosets with better combinations of properties are developed.

  20. High temperature future

    SciTech Connect

    Sheinkopf, K.

    1994-09-01

    During the past few years, there have been dramatic accomplishments and success of high temperature solar thermal systems and significant development of these systems. High temperature technologies, about 500 F and higher, such as dish engines, troughs, central receiver power towers and solar process heat systems, have been tested, demonstrated and used in an array of applications, including many cost-effective utility bulk power production and demand side supply projects in the United States. Large systems provide power and hot water to prisons, schools, nursing homes and other institutions. Joint ventures with industry, utility projects, laboratory design assistance and other activities are building a solid industry of US solar thermal systems ready for use today.

  1. High temperature materials characterization

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1990-01-01

    A lab facility for measuring elastic moduli up to 1700 C was constructed and delivered. It was shown that the ultrasonic method can be used to determine elastic constants of materials from room temperature to their melting points. The ease in coupling high frequency acoustic energy is still a difficult task. Even now, new coupling materials and higher power ultrasonic pulsers are being suggested. The surface was only scratched in terms of showing the full capabilities of either technique used, especially since there is such a large learning curve in developing proper methodologies to take measurements into the high temperature region. The laser acoustic system does not seem to have sufficient precision at this time to replace the normal buffer rod methodology.

  2. Design Of A Hybrid Jet Impingement / Microchannel Cooling Device For Densely Packed PV Cells Under High Concentration

    NASA Astrophysics Data System (ADS)

    Barrau, Jérôme; Rosell, Joan; Ibañez, Manel

    2010-10-01

    A hybrid jet impingement / microchannel cooling scheme was designed and applied to densely packed PV cells under high concentration. An experimental study allows validating the principles of the design and confirming its applicability to the cited system. In order to study the characteristics of the device in a wide range of conditions, a numerical model was developed and experimentally validated. The results allow evaluating the contributions of the cooling device to the performances of densely packed PV cells under high concentration. The main advantages of the system are related to its compactness, its good capacity of heat extraction associated to relatively low pressure losses and its capability to improve the temperature uniformity of the PV receiver with respect to other cooling schemes. These features improve the net electric output of the whole system and its reliability.

  3. Better high temperature sealing

    SciTech Connect

    Adams, W.V.

    1987-01-01

    Acceptance of welded metal bellows designs, superior seal face materials and advancement of environmental control systems has extended the limits of mechanical seals to the operating limits of the process systems themselves. The nonpusher type welded metal bellows designs have overcome past seal hang-up problems. Material combinations such as silicon carbide versus silicon carbide and silicon carbide versus tungsten carbide have proven to be capable of handling the harsh abrasives encountered on high temperature sealing applications. Steam purges have done a good job of flushing away the deposits and sludges that form on the atmospheric side of the seal and cause seal hang-up. Today's field experience shows that hot water at temperatures up to 350/sup 0/F in the seal cavity can be handled with nothing more than a bypass flush per API piping plan 11 as long as adequate vapor pressure of the fluid is available. For temperatures above 350/sup 0/F, only moderate cooling is now required on hot water applications, where full cooling and a reduction of the seal cavity temperature to something below 180/sup 0/F were once necessary. Initially, the move towards high temperature seals was made for safety, long seal life and reliability reasons. Users wanted seals on their equipment that would avoid the danger of catastrophic seal failures in the event the environmental control systems failed. More recently, the economic advantages of running seals hot have been recognized. It is estimated that an annual savings of $1,000 per inch of shaft size can be realized for every 100/sup 0/F of cooling requirements that can be removed from the seal cavity. This cost savings is due to the elimination or reduction of energy sources used to cool the mechanical seal.

  4. Ultra-High Intensity Magnetic Field Generation in Dense Plasma

    SciTech Connect

    Fisch, Nathaniel J

    2014-01-08

    I. Grant Objective The main objective of this grant proposal was to explore the efficient generation of intense currents. Whereasthefficient generation of electric current in low-­energy-­density plasma has occupied the attention of the magnetic fusion community for several decades, scant attention has been paid to carrying over to high-­energy-­density plasma the ideas for steady-­state current drive developed for low-­energy-­density plasma, or, for that matter, to inventing new methodologies for generating electric current in high-­energy-­density plasma. What we proposed to do was to identify new mechanisms to accomplish current generation, and to assess the operation, physics, and engineering basis of new forms of current drive in regimes appropriate for new fusion concepts.

  5. Direct numerical modeling of Saturn's dense rings at high optical depth

    NASA Astrophysics Data System (ADS)

    Richardson, Derek C.; Ballouz, Ronald-Louis; Morishima, Ryuji

    2015-11-01

    Saturn's B ring exhibits complex optical depth structure of uncertain origin. We are investigating the extent to which viscous overstability and/or gravitational wakes can give rise to this structure, via discrete particle numerical simulations. We use the parallelized N-body tree code pkdgrav with a soft-sphere collision model for detailed treatment of particle collisional physics, including multi-point persistent contact with static, sliding, rolling, and twisting friction forces. This enables us to perform local simulations with millions of particles, realistic sizes, and configurable material properties in high-optical-depth ring patches with near-linear scaling across multiple processors. Recent code improvements to the collision search algorithm provide a further roughly factor of 2 speedup. We present results from the first year of this study in which a library of simulations with different optical depths was constructed. Parameters explored include normal (dynamical) optical depths between 0.5 (approximately 100,000 particles) and 4.0 (approximately 8.3 million particles) in ring patches of dimension 6 by 6 critical Toomre wavelengths, using material parameters ranging from highly elastic smooth spheres to rough "gravel"-like particles. We also vary the particle internal densities to enhance (low density)/suppress (high density) viscous overstability in order to compare against gravitational instability in these different regimes. These libraries will be used to carry out simulated observations for comparison with Cassini CIRS temperature measurements and UVIS occulation data of Saturn's dense rings.

  6. High temperature strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); You, Tao (Inventor)

    2011-01-01

    A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

  7. High Temperature Piezoelectric Drill

    NASA Technical Reports Server (NTRS)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom

    2012-01-01

    Venus is one of the planets in the solar systems that are considered for potential future exploration missions. It has extreme environment where the average temperature is 460 deg C and its ambient pressure is about 90 atm. Since the existing actuation technology cannot maintain functionality under the harsh conditions of Venus, it is a challenge to perform sampling and other tasks that require the use of moving parts. Specifically, the currently available electromagnetic actuators are limited in their ability to produce sufficiently high stroke, torque, or force. In contrast, advances in developing electro-mechanical materials (such as piezoelectric and electrostrictive) have enabled potential actuation capabilities that can be used to support such missions. Taking advantage of these materials, we developed a piezoelectric actuated drill that operates at the temperature range up to 500 deg C and the mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) configuration. The detailed results of our study are presented in this paper

  8. Instabilities of High Temperature Superconductors

    PubMed Central

    Matthias, B. T.; Corenzwit, E.; Cooper, A. S.; Longinotti, L. D.

    1971-01-01

    We have observed the transition temperature of both the cubic and tetragonal phases of several high-temperature β-W superconductors. The instability of the cubic lattice appears to be characteristic of high-temperature superconductors. PMID:16591897

  9. High temperature detonator

    DOEpatents

    Johnson, James O.; Dinegar, Robert H.

    1988-01-01

    A detonator assembly is provided which is usable at high temperatures about 300.degree. C. A detonator body is provided with an internal volume defining an anvil surface. A first acceptor explosive is disposed on the anvil surface. A donor assembly having an ignition element, an explosive material, and a flying plate, are placed in the body effective to accelerate the flying plate to impact the first acceptor explosive on the anvil for detonating the first acceptor explosive. A second acceptor explosive is eccentrically located in detonation relationship with the first acceptor explosive to thereafter effect detonation of a main charge.

  10. High temperature geophysical instrumentation

    SciTech Connect

    Hardee, H.C.

    1988-06-01

    The instrumentation development program was to proceed in parallel with scientific research and was driven by the needs of researchers. The development of these instruments has therefore included numerous geophysical field tests, many of which have resulted in the publication of scientific articles. This paper is a brief summary of some of the major geophysical instruments that have been developed and tested under the High Temperature Geophysics Program. These instruments are briefly described and references are given for further detailed information and for scientific papers that have resulted from the use of these instruments. 9 refs., 14 figs.

  11. High temperature drilling fluids

    SciTech Connect

    Stong, R.E.; Walinsky, S.W.

    1986-01-28

    This patent describes an aqueous drilling fluid suitable for high-temperature use. This fluid is composed of a water base. Clay is suspended in the base and from about 0.01-25 pounds per barrel total composition of a hydrolyzed terpolymer of maleic anhydride, styrene and a third monomer selected from acrylamide, methacrylamide, acrylic acid and metacrylic acid. The molar ratio of maleic anhydride to styrene to the third monomer is from about 30:10:60 to 50:40:10, and the alkali metal, ammonium and lower aliphatic amine salts thereof, the weight-average molecular weight of the hydrolyzed terpolymer is from about 500-10,000.

  12. High Temperature Protonic Conductors

    NASA Technical Reports Server (NTRS)

    Dynys, Fred; Berger, Marie-Helen; Sayir, Ali

    2007-01-01

    High Temperature Protonic Conductors (HTPC) with the perovskite structure are envisioned for electrochemical membrane applications such as H2 separation, H2 sensors and fuel cells. Successive membrane commercialization is dependent upon addressing issues with H2 permeation rate and environmental stability with CO2 and H2O. HTPC membranes are conventionally fabricated by solid-state sintering. Grain boundaries and the presence of intergranular second phases reduce the proton mobility by orders of magnitude than the bulk crystalline grain. To enhanced protonic mobility, alternative processing routes were evaluated. A laser melt modulation (LMM) process was utilized to fabricate bulk samples, while pulsed laser deposition (PLD) was utilized to fabricate thin film membranes . Sr3Ca(1+x)Nb(2-x)O9 and SrCe(1-x)Y(x)O3 bulk samples were fabricated by LMM. Thin film BaCe(0.85)Y(0.15)O3 membranes were fabricated by PLD on porous substrates. Electron microscopy with chemical mapping was done to characterize the resultant microstructures. High temperature protonic conduction was measured by impedance spectroscopy in wet air or H2 environments. The results demonstrate the advantage of thin film membranes to thick membranes but also reveal the negative impact of defects or nanoscale domains on protonic conductivity.

  13. High temperature filter materials

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M.; Tressler, R.E.

    1992-12-01

    Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments have on the stability of porous ceramic filter materials, as well as to assess the influence of these effects on filter operating performance and life. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100{degrees}C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter {times} 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.

  14. High temperature filter materials

    SciTech Connect

    Alvin, M.A.; Lippert, T.E.; Bachovchin, D.M. . Science and Technology Center); Tressler, R.E. )

    1992-01-01

    Objectives of this program are to identify the potential long-term thermal/chemical effects that advanced coal-based power generating system environments have on the stability of porous ceramic filter materials, as well as to assess the influence of these effects on filter operating performance and life. We have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100[degrees]C) under oxidizing conditions which contain gas phase alkali species. Testing has typically been performed in two continuous flow-through, high temperature test facilities at the Westinghouse Science and Technology Center, using 7 cm diameter [times] 6.4 mm thick discs. (Alvin, 1992) Each disc of ceramic filter material is exposed for periods of 100 to 3,000 hours in duration. Additional efforts have been performed at Westinghouse to broaden our understanding of the stability of cordierite, cordierite-silicon nitride, reaction and sintered silicon nitride, and clay bonded silicon carbide under similar simulated advanced coal fired process conditions. The results of these efforts are presented in this paper.

  15. High Temperature Aquifer Storage

    NASA Astrophysics Data System (ADS)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2015-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Apart from the hydrogeological conditions, high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. After one year of planning, construction, and the successful drilling of a research well to 495 m b.s.l. the first large scale heat storage test in the Malm aquifer was finished just before Christmas 2014. An enormous technical challenge was the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10-50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye. Injection and production rates were 15 L/s. About 4 TJ of heat energy were necessary to achieve the desired water temperatures. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for the analysis of the concentration of the tracers and the cation concentrations at sampling intervals of down to 15 minutes. Additional water samples were taken and analyzed for major ions and trace elements in the laboratory. The disassembled heat exchanger proved that precipitation was successfully prevented by adding CO2 to the water before heating

  16. High Temperature Aquifer Storage

    NASA Astrophysics Data System (ADS)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2016-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. Apart from high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. An enormous technical challenge is the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10 - 50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye, into a depth of about 300 m b.s.l. resp. 470 m b.s.l. Injection and production rates were 15 L/s. To achieve the desired water temperatures, about 4 TJ of heat energy were necessary. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for analysing the concentration of the dyes and the major cations at sampling intervals of down to 15 minutes. Additional water samples were taken and analysed in the laboratory. The disassembled heat exchanger prooved that precipitation was successfully prevented by adding CO2 to the water before heating. Nevertheless, hydrochemical data proved both, dissolution and precipitation processes in the aquifer. This was also suggested by the hydrochemical modelling with PhreeqC and is traced back to mixture dissolution and changing

  17. High temperature interfacial superconductivity

    SciTech Connect

    Bozovic, Ivan; Logvenov, Gennady; Gozar, Adrian Mihai

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  18. High-pressure radiative conductivity of dense silicate glasses with potential implications for dark magmas.

    PubMed

    Murakami, Motohiko; Goncharov, Alexander F; Hirao, Naohisa; Masuda, Ryo; Mitsui, Takaya; Thomas, Sylvia-Monique; Bina, Craig R

    2014-01-01

    The possible presence of dense magmas at Earth's core-mantle boundary is expected to substantially affect the dynamics and thermal evolution of Earth's interior. However, the thermal transport properties of silicate melts under relevant high-pressure conditions are poorly understood. Here we report in situ high-pressure optical absorption and synchrotron Mössbauer spectroscopic measurements of iron-enriched dense silicate glasses, as laboratory analogues for dense magmas, up to pressures of 85 GPa. Our results reveal a significant increase in absorption coefficients, by almost one order of magnitude with increasing pressure to ~50 GPa, most likely owing to gradual changes in electronic structure. This suggests that the radiative thermal conductivity of dense silicate melts may decrease with pressure and so may be significantly smaller than previously expected under core-mantle boundary conditions. Such dark magmas heterogeneously distributed in the lower mantle would result in significant lateral heterogeneity of heat flux through the core-mantle boundary. PMID:25384573

  19. High Temperature Superconducting Materials Database

    National Institute of Standards and Technology Data Gateway

    SRD 149 NIST High Temperature Superconducting Materials Database (Web, free access)   The NIST High Temperature Superconducting Materials Database (WebHTS) provides evaluated thermal, mechanical, and superconducting property data for oxides and other nonconventional superconductors.

  20. High Temperature Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Ioannidou, A. A.; Rull, M.; Martin-Gonzalez, M.; Moure, A.; Jacquot, A.; Niarchos, D.

    2014-07-01

    The use of microwave energy for materials processing has a major potential and real advantages over conventional heating such as (1) time and energy savings, (2) rapid heating rates (volumetric heating vs. conduction), (3) considerably reduced processing time and temperature, (4) fine microstructures and hence improved mechanical properties and better product performance, and (5) finally lower environmental impact. In this study, we investigated the use of microwave-assisted synthesis to synthesize a series of Co1- x Fe x Sb3 using this novel approach, which gave high quality materials with little or no impurities in a fraction of the time needed for conventional synthesis. X-ray diffraction analysis was used to examine the structure and the lattice parameters of the samples, while scanning electron microscopy with energy dispersive x-ray spectroscopy was used to study the morphology of the compounds. The samples were sintered by spark plasma sintering, and the highest ZT of 0.33 was obtained for x = 0.2 at 700 K.

  1. Fabrication and processing of high-strength densely packed carbon nanotube yarns without solution processes.

    PubMed

    Liu, Kai; Zhu, Feng; Liu, Liang; Sun, Yinghui; Fan, Shoushan; Jiang, Kaili

    2012-06-01

    Defects of carbon nanotubes, weak tube-tube interactions, and weak carbon nanotube joints are bottlenecks for obtaining high-strength carbon nanotube yarns. Some solution processes are usually required to overcome these drawbacks. Here we fabricate ultra-long and densely packed pure carbon nanotube yarns by a two-rotator twisting setup with the aid of some tensioning rods. The densely packed structure enhances the tube-tube interactions, thus making high tensile strengths of carbon nanotube yarns up to 1.6 GPa. We further use a sweeping laser to thermally treat as-produced yarns for recovering defects of carbon nanotubes and possibly welding carbon nanotube joints, which improves their Young's modulus by up to ∼70%. The spinning and laser sweeping processes are solution-free and capable of being assembled together to produce high-strength yarns continuously as desired. PMID:22538869

  2. Fabrication and processing of high-strength densely packed carbon nanotube yarns without solution processes

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Zhu, Feng; Liu, Liang; Sun, Yinghui; Fan, Shoushan; Jiang, Kaili

    2012-05-01

    Defects of carbon nanotubes, weak tube-tube interactions, and weak carbon nanotube joints are bottlenecks for obtaining high-strength carbon nanotube yarns. Some solution processes are usually required to overcome these drawbacks. Here we fabricate ultra-long and densely packed pure carbon nanotube yarns by a two-rotator twisting setup with the aid of some tensioning rods. The densely packed structure enhances the tube-tube interactions, thus making high tensile strengths of carbon nanotube yarns up to 1.6 GPa. We further use a sweeping laser to thermally treat as-produced yarns for recovering defects of carbon nanotubes and possibly welding carbon nanotube joints, which improves their Young's modulus by up to ~70%. The spinning and laser sweeping processes are solution-free and capable of being assembled together to produce high-strength yarns continuously as desired.

  3. Extended application of Kohn-Sham first-principles molecular dynamics method with plane wave approximation at high energy—From cold materials to hot dense plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, Shen; Wang, Hongwei; Kang, Wei; Zhang, Ping; He, X. T.

    2016-04-01

    An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of electronic structures. This gives an edge to the extended method in the calculation of mixtures of plasmas composed of heterogeneous ions, high-Z dense plasmas, lowering of ionization potentials, X-ray absorption/emission spectra, and opacities, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.

  4. High-temperature piezoelectric sensing.

    PubMed

    Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

    2013-01-01

    Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

  5. High-Temperature Piezoelectric Sensing

    PubMed Central

    Jiang, Xiaoning; Kim, Kyungrim; Zhang, Shujun; Johnson, Joseph; Salazar, Giovanni

    2014-01-01

    Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented. PMID:24361928

  6. Dense distributed temperature sensing to infer local seepage fluxes in coastal areas

    NASA Astrophysics Data System (ADS)

    Hilgersom, Koen; van de Giesen, Nick

    2014-05-01

    In many deltas, land surfaces are largely below sea level, and consequently suffering from saline groundwater seepage. This phenomenon affects the fresh water supply for, for example, agriculture and drinking water production. In many of those deltas, sea level rise and land subsidence enhance these problems. Depending on the geology, the seepage fluxes can occur both distributed and locally. Local seepage occurs through ancient channels that were filled with higher-conductive material at later times, but also works its way up via small vents through the soil. The latter is called boil seepage and usually is the most saline of the mentioned seepage types. Boils commonly appear in ditches and canals, since the pressure gradient is most of the time larger compared to the surrounding area. Although boils appear only as local point inflows, their high discharge and consequent salt flux can make them contribute for over 70% of the salt flux into lowland water systems (de Louw et al., 2010). Seepage measurement methods include the application of so-called seepage meters and tracers like temperature. Conventional methods using temperature differences between groundwater and surface water require drilling temperature sensors into the soil. Because the locations of boils are sensitive to disturbances of the soil, we measure the seepage flux by measuring a 3D temperature profile in the surface water above the boil instead. The seepage flux is inferred from a numerical surface water model that includes salt and temperature transport. Laboratory and field results show the onset of stratification because of the denser groundwater. In the winter situation, the temperature of the groundwater is relatively high, and double diffusive processes may play a role, mainly because there is negligible lateral flow most of the time, when the downstream pumping station is not active. Therefore, a model is set up that is well able to represent these double diffusive processes. References De

  7. High-Resolution Strain Analysis of the Human Heart with Fast-DENSE

    NASA Astrophysics Data System (ADS)

    Aletras, Anthony H.; Balaban, Robert S.; Wen, Han

    1999-09-01

    Single breath-hold displacement data from the human heart were acquired with fast-DENSE (fast displacement encoding with stimulated echoes) during systolic contraction at 2.5 × 2.5 mm in-plane resolution. Encoding strengths of 0.86-1.60 mm/π were utilized in order to extend the dynamic range of the phase measurements and minimize effects of physiologic and instrument noise. The noise level in strain measurements for both contraction and dilation corresponded to a strain value of 2.8%. In the human heart, strain analysis has sufficient resolution to reveal transmural variation across the left ventricular wall. Data processing required minimal user intervention and provided a rapid quantitative feedback. The intrinsic temporal integration of fast-DENSE achieves high accuracy at the expense of temporal resolution.

  8. Dense 3D Reconstruction from High Frame-Rate Video Using a Static Grid Pattern.

    PubMed

    Sagawa, Ryusuke; Furukawa, Ryo; Kawasaki, Hiroshi

    2014-09-01

    Dense 3D reconstruction of fast moving objects could contribute to various applications such as body structure analysis, accident avoidance, and so on. In this paper, we propose a technique based on a one-shot scanning method, which reconstructs 3D shapes for each frame of a high frame-rate video capturing the scenes projected by a static pattern. To avoid instability of image processing, we restrict the number of colors used in the pattern to less than two. The proposed technique comprises (1) an efficient algorithm to eliminate ambiguity of projected parallel-line patterns by using intersection points, (2) a batch reconstruction algorithm of multiple frames by using spatio-temporal constraints, and (3) an efficient detection method of color-encoded grid pattern based on de Bruijn sequence. In the experiments, the line detection algorithm worked effectively and the dense reconstruction algorithm produces accurate and robust results. We also show the improved results by using temporal constraints. Finally, the dense reconstructions of fast moving objects in a high frame-rate video are presented. PMID:26352228

  9. Survival of high p{sub T} light and heavy flavors in a dense medium

    SciTech Connect

    Kopeliovich, B. Z.

    2011-04-26

    This talk presents an attempt at a critical overview of the current status of modeling for high-p{sub T} processes in nuclei. In particular, it includes discussion of the space-time development of hadronization of highly virtual light and heavy partons, and the related time scales; the role of early production and subsequent attenuation of pre-hadrons in a dense medium. We identify several challenging problems within the current interpretation of high-p{sub T} processes and propose solutions for some of them.

  10. Effect of dense plasmas on exchange-energy shifts in highly charged ions: An alternative approach for arbitrary perturbation potentials

    SciTech Connect

    Rosmej, F.; Bennadji, K.; Lisitsa, V. S.

    2011-09-15

    An alternative method of calculation of dense plasma effects on exchange-energy shifts {Delta}E{sub x} of highly charged ions is proposed which results in closed expressions for any plasma or perturbation potential. The method is based on a perturbation theory expansion for the inner atomic potential produced by charged plasma particles employing the Coulomb Green function method. This approach allows us to obtain analytic expressions and scaling laws with respect to the electron temperature T, density n{sub e}, and nuclear charge Z. To demonstrate the power of the present method, two specific models were considered in detail: the ion sphere model (ISM) and the Debye screening model (DSM). We demonstrate that analytical expressions can be obtained even for the finite temperature ISM. Calculations have been carried out for the singlet 1s2p{sup 1} P{sub 1} and triplet 1s2p{sup 3} P{sub 1} configurations of He-like ions with charge Z that can be observed in dense plasmas via the He-like resonance and intercombination lines. Finally we discuss recently available purely numerical calculations and experimental data.

  11. High-pressure superconducting phase diagram of 6Li: Isotope effects in dense lithium

    PubMed Central

    Schaeffer, Anne Marie; Temple, Scott R.; Bishop, Jasmine K.; Deemyad, Shanti

    2015-01-01

    We measured the superconducting transition temperature of 6Li between 16 and 26 GPa, and report the lightest system to exhibit superconductivity to date. The superconducting phase diagram of 6Li is compared with that of 7Li through simultaneous measurement in a diamond anvil cell (DAC). Below 21 GPa, Li exhibits a direct (the superconducting coefficient, α, Tc∝M−α, is positive), but unusually large isotope effect, whereas between 21 and 26 GPa, lithium shows an inverse superconducting isotope effect. The unusual dependence of the superconducting phase diagram of lithium on its atomic mass opens up the question of whether the lattice quantum dynamic effects dominate the low-temperature properties of dense lithium. PMID:25538300

  12. High-pressure superconducting phase diagram of 6Li: isotope effects in dense lithium.

    PubMed

    Schaeffer, Anne Marie; Temple, Scott R; Bishop, Jasmine K; Deemyad, Shanti

    2015-01-01

    We measured the superconducting transition temperature of (6)Li between 16 and 26 GPa, and report the lightest system to exhibit superconductivity to date. The superconducting phase diagram of (6)Li is compared with that of (7)Li through simultaneous measurement in a diamond anvil cell (DAC). Below 21 GPa, Li exhibits a direct (the superconducting coefficient, α, T(c) proportional M(-α), is positive), but unusually large isotope effect, whereas between 21 and 26 GPa, lithium shows an inverse superconducting isotope effect. The unusual dependence of the superconducting phase diagram of lithium on its atomic mass opens up the question of whether the lattice quantum dynamic effects dominate the low-temperature properties of dense lithium.

  13. On axial temperature gradients due to large pressure drops in dense fluid chromatography.

    PubMed

    Colgate, Sam O; Berger, Terry A

    2015-03-13

    The effect of energy degradation (Degradation is the creation of net entropy resulting from irreversibility.) accompanying pressure drops across chromatographic columns is examined with regard to explaining axial temperature gradients in both high performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). The observed effects of warming and cooling can be explained equally well in the language of thermodynamics or fluid dynamics. The necessary equivalence of these treatments is reviewed here to show the legitimacy of using whichever one supports the simpler determination of features of interest. The determination of temperature profiles in columns by direct application of the laws of thermodynamics is somewhat simpler than applying them indirectly by solving the Navier-Stokes (NS) equations. Both disciplines show that the preferred strategy for minimizing the reduction in peak quality caused by temperature gradients is to operate columns as nearly adiabatically as possible (i.e. as Joule-Thomson expansions). This useful fact, however, is not widely familiar or appreciated in the chromatography community due to some misunderstanding of the meaning of certain terms and expressions used in these disciplines. In fluid dynamics, the terms "resistive heating" or "frictional heating" have been widely used as synonyms for the dissipation function, Φ, in the NS energy equation. These terms have been widely used by chromatographers as well, but often misinterpreted as due to friction between the mobile phase and the column packing, when in fact Φ describes the increase in entropy of the system (dissipation, ∫TdSuniv>0) due to the irreversible decompression of the mobile phase. Two distinctly different contributions to the irreversibility are identified; (1) ΔSext, viscous dissipation of work done by the external surroundings driving the flow (the pump) contributing to its warming, and (2) ΔSint, entropy change accompanying decompression of

  14. High-temperature-measuring device

    DOEpatents

    Not Available

    1981-01-27

    A temperature measuring device for very high design temperatures (to 2000/sup 0/C) is described. The device comprises a homogenous base structure preferably in the form of a sphere or cylinder. The base structure contains a large number of individual walled cells. The base structure has a decreasing coefficient of elasticity within the temperature range being monitored. A predetermined quantity of inert gas is confined within each cell. The cells are dimensonally stable at the normal working temperature of the device. Increases in gaseous pressure within the cells will permanently deform the cell walls at temperatures within the high temperature range to be measured. Such deformation can be correlated to temperature by calibrating similarly constructed devices under known time and temperature conditions.

  15. Connectivity, Doping, and Anisotropy in Highly Dense Magnesium Diboride (MgB2)

    NASA Astrophysics Data System (ADS)

    Li, Guangze

    Magnesium diboride (MgB2) is a superconducting material which can be potentially used in many applications such as magnetic resonance imaging system (MRI), wind turbine generators and high energy physics facilities. The major advantages of MgB2 over other superconductors include its relatively high critical temperature of about 39 K, its low cost of raw materials, its simple crystal structure, and its round multifilament form when in the form of superconducting wires. Over the past fourteen years, much effort has been made to develop MgB2 wires with excellent superconducting properties, particularly the critical current density J c. However, this research has been limited by technical difficulties such as high porosity and weak connectivity in MgB2, relatively small flux pinning strength, low upper critical field B c2 and relatively high anisotropy. The goal of this dissertation is to understand the relationship between superconducting properties, microstructure, and reaction mechanisms in MgB 2. In particular, the influences of connectivity, B c2, anisotropy and flux pinning were investigated in terms of the effects of these variables on the Jcs and n-values of MgB2 superconducting wires (n-value is a parameter which indicates the sharpness of resistive V-I transition). The n -values of traditional "Powder in Tube (PIT)" processed MgB2 wires were improved by optimizing precursor species after the identification of microstructural defects such as so-called "sausaging problems". Also, it was found that "high porosity and weak connectivity" was one of the most critical issues which limited the J c performance in typical MgB2. To overcome this problem, highly dense, well-connected MgB2 conductors were successfully fabricated by adopting an innovative "Advanced Internal Magnesium Infiltration (AIMI)" process. A careful study on the reaction kinetics together with the microstructural evidence demonstrated how the MgB2 layer was formed as the infiltration process

  16. High temperature interface superconductivity

    DOE PAGES

    Gozar, A.; Bozovic, I.

    2016-01-20

    High-Tc superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-Tc Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. Here, wemore » conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.« less

  17. High temperature interface superconductivity

    NASA Astrophysics Data System (ADS)

    Gozar, A.; Bozovic, I.

    2016-02-01

    High-Tc superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-Tc Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both 'passive' hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  18. Very low electron temperature in warm dense matter formed by focused picosecond soft x-ray laser pulses

    SciTech Connect

    Ishino, Masahiko Hasegawa, Noboru; Nishikino, Masaharu; Kawachi, Tetsuya; Yamagiwa, Mitsuru; Pikuz, Tatiana; Skobelev, Igor; Faenov, Anatoly; Inogamov, Nail

    2014-11-14

    We investigated the optical emission from the ablating surfaces induced by the irradiations of soft x-ray laser (SXRL) pulses with the aim of estimation of the maximum electron temperature. No emission signal in the spectral range of 400–800 nm could be observed despite the formation of damage structures on the target surfaces. Hence, we estimated an upper limit for the electron temperature of 0.4–0.7 eV for the process duration of 100–1000 ps. Our results imply that the ablation and/or surface modification by the SXRL is not accompanied by plasma formation but is induced by thermo-mechanical pressure, which is so called a spallative ablation. This spallative ablation process occurs in the low electron temperature region of a non-equilibrium state of warm dense matter.

  19. High-temperature ceramic receivers

    SciTech Connect

    Jarvinen, P. O.

    1980-01-01

    An advanced ceramic dome cavity receiver is discussed which heats pressurized gas to temperatures above 1800/sup 0/F (1000/sup 0/C) for use in solar Brayton power systems of the dispersed receiver/dish or central receiver type. Optical, heat transfer, structural, and ceramic material design aspects of the receiver are reported and the development and experimental demonstration of a high-temperature seal between the pressurized gas and the high-temperature silicon carbide dome material is described.

  20. Stabilized Acoustic Levitation of Dense Materials Using a High-Powered Siren

    NASA Technical Reports Server (NTRS)

    Gammell, P. M.; Croonquist, A.; Wang, T. G.

    1982-01-01

    Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence.

  1. Synthesis of super-dense phase of aluminum under extreme pressure and temperature conditions created by femtosecond laser pulses in sapphire

    SciTech Connect

    Mizeikis, Vygantas; Vailionis, Arturas; Gamaly, Eugene G.; Yang, Wenge; Rode, Andrei V.; Juodkazis, Saulius

    2012-06-26

    We describe synthesis of a new super-dense phase of aluminum under extreme pressure and temperature conditions created by laser-induced microexplosions in sapphire. Micro explosions in sub-micrometer sized regions of sapphire were induced by tightly-focused femtosecond laser pulses with a temporal length of {approx} 100 fs and an energy of {approx} 100 nJ. Fast, explosive expansion of photogenerated high-density plasma created strong heating and pressure transients with peak temperature and pressure of {approx} 105 K and 10 TPa, respectively. Partial decomposition of sapphire in the shock-compressed sapphire led to formation of nanocrystalline bcc-Al phase, which is different from ambient fcc-Al phase, and was permanently preserved by fast quenching. The existence of super-dense bcc-Al phase was confirmed using X-ray diffraction technique. This is the first observation of bcc-Al phase, which so far has been only predicted theoretically, and a demonstration that laser-induced micro explosions technique enables simple, safe and cost-efficient access to extreme pressures and temperatures without the tediousness typical to traditional techniques that use diamond anvil cells, gas guns, explosives, or megajoule-class lasers.

  2. High Temperature Solar Cell Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Raffaelle, Ryne P.; Merritt, Danielle

    2004-01-01

    The majority of satellites and near-earth probes developed to date have used photovoltaic arrays for power generation. If future mission to probe environments close to the sun will be able to use photovoltaic power, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. In this paper, we derive the optimum bandgap as a function of the operating temperature.

  3. Advanced High Temperature Structural Seals

    NASA Astrophysics Data System (ADS)

    Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Rorabaugh, Michael; Shorey, Mark

    2002-10-01

    This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 pound payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs.

  4. Advanced High Temperature Structural Seals

    NASA Technical Reports Server (NTRS)

    Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Rorabaugh, Michael; Shorey, Mark

    2002-01-01

    This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 pound payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs.

  5. Development of high strength, high temperature ceramics

    NASA Technical Reports Server (NTRS)

    Hall, W. B.

    1982-01-01

    Improvement in the high-pressure turbopumps, both fuel and oxidizer, in the Space Shuttle main engine were considered. The operation of these pumps is limited by temperature restrictions of the metallic components used in these pumps. Ceramic materials that retain strength at high temperatures and appear to be promising candidates for use as turbine blades and impellers are discussed. These high strength materials are sensitive to many related processing parameters such as impurities, sintering aids, reaction aids, particle size, processing temperature, and post thermal treatment. The specific objectives of the study were to: (1) identify and define the processing parameters that affect the properties of Si3N4 ceramic materials, (2) design and assembly equipment required for processing high strength ceramics, (3) design and assemble test apparatus for evaluating the high temperature properties of Si3N4, and (4) conduct a research program of manufacturing and evaluating Si3N4 materials as applicable to rocket engine applications.

  6. Highly aligned dense carbon nanotube sheets induced by multiple stretching and pressing

    NASA Astrophysics Data System (ADS)

    Liu, Qianli; Li, Min; Gu, Yizhuo; Zhang, Yongyi; Wang, Shaokai; Li, Qingwen; Zhang, Zuoguang

    2014-03-01

    The CNT sheet fabricated by the floating catalyst chemical vapor deposition (CVD) method has attracted great attention due to its easy fabrication process and promising mass production at low cost. However, the randomly oriented CNT sheet with a loose stacking density shows relatively poor mechanical properties. In this work, a highly aligned dense CNT sheet was successfully fabricated by a simple process of two-time stretching and pressing of a multilayered CVD-grown CNT sheet. Drastic nanotube rearrangements occurred during stretching and pressing processes. A polymer-like tensile necking behavior was observed during the stretching process, accompanied by inter-tube junction breakage due to long-distance slippage. Simultaneously the CNT sheet was thickened after the stretching process due to the increase of the inter-layer space, which could be effectively eliminated by the following pressing treatment. After two-time stretching and pressing, a highly aligned dense CNT sheet was fabricated with the volume density increasing to 0.98 g cm-3 (by 109%) and the tensile strength increasing to 598 MPa (by 221%) compared to the as-prepared CNT sheet.

  7. X-ray emission from high temperature plasmas

    NASA Technical Reports Server (NTRS)

    Harries, W. L.

    1976-01-01

    The physical processes occurring in plasma focus devices were studied. These devices produce dense high temperature plasmas, which emit X rays of hundreds of KeV energy and one to ten billion neutrons per pulse. The processes in the devices seem related to solar flare phenomena, and would also be of interest for controlled thermonuclear fusion applications. The high intensity, short duration bursts of X rays and neutrons could also possibly be used for pumping nuclear lasers.

  8. High dimensional data clustering by partitioning the hypergraphs using dense subgraph partition

    NASA Astrophysics Data System (ADS)

    Sun, Xili; Tian, Shoucai; Lu, Yonggang

    2015-12-01

    Due to the curse of dimensionality, traditional clustering methods usually fail to produce meaningful results for the high dimensional data. Hypergraph partition is believed to be a promising method for dealing with this challenge. In this paper, we first construct a graph G from the data by defining an adjacency relationship between the data points using Shared Reverse k Nearest Neighbors (SRNN). Then a hypergraph is created from the graph G by defining the hyperedges to be all the maximal cliques in the graph G. After the hypergraph is produced, a powerful hypergraph partitioning method called dense subgraph partition (DSP) combined with the k-medoids method is used to produce the final clustering results. The proposed method is evaluated on several real high-dimensional datasets, and the experimental results show that the proposed method can improve the clustering results of the high dimensional data compared with applying k-medoids method directly on the original data.

  9. High temperature turbine engine structure

    DOEpatents

    Boyd, Gary L.

    1990-01-01

    A high temperature turbine engine includes a hybrid ceramic/metallic rotor member having ceramic/metal joint structure. The disclosed joint is able to endure higher temperatures than previously possible, and aids in controlling heat transfer in the rotor member.

  10. Advanced High Temperature Structural Seals

    NASA Technical Reports Server (NTRS)

    Newquist, Charles W.; Verzemnieks, Juris; Keller, Peter C.; Shorey, Mark W.; Steinetz, Bruce (Technical Monitor)

    2000-01-01

    This program addresses the development of high temperature structural seals for control surfaces for a new generation of small reusable launch vehicles. Successful development will contribute significantly to the mission goal of reducing launch cost for small, 200 to 300 lb payloads. Development of high temperature seals is mission enabling. For instance, ineffective control surface seals can result in high temperature (3100 F) flows in the elevon area exceeding structural material limits. Longer sealing life will allow use for many missions before replacement, contributing to the reduction of hardware, operation and launch costs. During the first phase of this program the existing launch vehicle control surface sealing concepts were reviewed, the aerothermal environment for a high temperature seal design was analyzed and a mock up of an arc-jet test fixture for evaluating seal concepts was fabricated.

  11. High temperature structural insulating material

    DOEpatents

    Chen, W.Y.

    1984-07-27

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800/sup 0/C), low thermal conductivity (below about 0.2 W/m/sup 0/C), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800/sup 0/C, a diameter within the range of 20-200 ..mu..m, and a wall thickness in the range of about 2 to 4 ..mu..m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  12. High temperature structural insulating material

    DOEpatents

    Chen, Wayne Y.

    1987-01-01

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800.degree. C.), low thermal conductivity (below about 0.2 W/m.degree. C.), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800.degree. C., a diameter within the range of 20-200 .mu.m, and a wall thickness in the range of about 2-4 .mu.m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  13. High temperature structural insulating material

    DOEpatents

    Chen, Wayne Y.

    1987-01-06

    A high temperature structural insulating material useful as a liner for cylinders of high temperature engines through the favorable combination of high service temperature (above about 800.degree. C.), low thermal conductivity (below about 0.2 W/m.degree. C.), and high compressive strength (above about 250 psi). The insulating material is produced by selecting hollow ceramic beads with a softening temperature above about 800.degree. C., a diameter within the range of 20-200 .mu.m, and a wall thickness in the range of about 2-4 .mu.m; compacting the beads and a compatible silicate binder composition under pressure and sintering conditions to provide the desired structural form with the structure having a closed-cell, compact array of bonded beads.

  14. Containerless high temperature calorimeter apparatus

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Nisen, D. B. (Inventor)

    1981-01-01

    A calorimeter apparatus for measuring high temperature thermophysical properties of materials is disclosed which includes a containerless heating apparatus in which the specimen is suspended and heated by electron bombardment.

  15. High-temperature structural intermetallics

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Ito, K.

    2000-01-01

    In the last one and a half decades, a great deal of fundamental and developmental research has been made on high-temperature structural intermetallics aiming at the implementation of these intermetallics in aerospace, automotive and land-based applications. These intermetallics include aluminides formed with either titanium, nickel or iron and silicides formed with transition metals. Of these high-temperature intermetallics, TiAl-based alloys with great potential in both aerospace and automotive applications have been attracting particular attention. Recently TiAl turbocharger wheels have finally started being used for turbochargers for commercial passenger cars of a special type. The current status of the research and development of these high-temperature intermetallics is summarized and a perspective on what directions future research and development of high-temperature intermetallics should take is provided.

  16. Equation of state of dense plasmas: Orbital-free molecular dynamics as the limit of quantum molecular dynamics for high-Z elements

    SciTech Connect

    Danel, J.-F.; Blottiau, P.; Kazandjian, L.; Piron, R.; Torrent, M.

    2014-10-15

    The applicability of quantum molecular dynamics to the calculation of the equation of state of a dense plasma is limited at high temperature by computational cost. Orbital-free molecular dynamics, based on a semiclassical approximation and possibly on a gradient correction, is a simulation method available at high temperature. For a high-Z element such as lutetium, we examine how orbital-free molecular dynamics applied to the equation of state of a dense plasma can be regarded as the limit of quantum molecular dynamics at high temperature. For the normal mass density and twice the normal mass density, we show that the pressures calculated with the quantum approach converge monotonically towards those calculated with the orbital-free approach; we observe a faster convergence when the orbital-free approach includes the gradient correction. We propose a method to obtain an equation of state reproducing quantum molecular dynamics results up to high temperatures where this approach cannot be directly implemented. With the results already obtained for low-Z plasmas, the present study opens the way for reproducing the quantum molecular dynamics pressure for all elements up to high temperatures.

  17. High temperature current mirror amplifier

    DOEpatents

    Patterson, III, Raymond B.

    1984-05-22

    A high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg.

  18. Dense Plasma Focus Z-pinches for High Gradient Particle Acceleration

    SciTech Connect

    Tang, V; Adams, M L; Rusnak, B

    2009-07-24

    The final Z-pinch stage of a Dense Plasma Focus (DPF) could be used as a simple, compact, and potentially rugged plasma-based high-gradient accelerator with fields at the 100 MV/m level. In this paper we review previously published experimental beam data that indicate the feasibility of such an DPF-based accelerator, qualitatively discuss the physical acceleration processes in terms of the induced voltages, and as a starting point examine the DPF acceleration potential by numerically applying a self-consistent DPF system model that includes the induced voltage from both macroscopic and instability driven plasma dynamics. Applications to the remote detection of high explosives and a multi-staged acceleration concept are briefly discussed.

  19. The Very High Temperature Reactor

    SciTech Connect

    Hans D. Gougar; David A. Petti

    2011-06-01

    The High Temperature Reactor (HTR) and Very High Temperature Reactor (VHTR) are types of nuclear power plants that, as the names imply, operate at temperatures above those of the conventional nuclear power plants that currently generate electricity in the US and other countries. Like existing nuclear plants, heat generated from the fission of uranium or plutonium atoms is carried off by a working fluid and can be used generate electricity. The very hot working fluid also enables the VHTR to drive other industrial processes that require high temperatures not achievable by conventional nuclear plants (Figure 1). For this reason, the VHTR is being considered for non-electrical energy applications. The reactor and power conversion system are constructed using special materials that make a core meltdown virtually impossible.

  20. Dense Plasma Focus - From Alternative Fusion Source to Versatile High Energy Density Plasma Source for Plasma Nanotechnology

    NASA Astrophysics Data System (ADS)

    Rawat, R. S.

    2015-03-01

    The dense plasma focus (DPF), a coaxial plasma gun, utilizes pulsed high current electrical discharge to heat and compress the plasma to very high density and temperature with energy densities in the range of 1-10 × 1010 J/m3. The DPF device has always been in the company of several alternative magnetic fusion devices as it produces intense fusion neutrons. Several experiments conducted on many different DPF devices ranging over several order of storage energy have demonstrated that at higher storage energy the neutron production does not follow I4 scaling laws and deteriorate significantly raising concern about the device's capability and relevance for fusion energy. On the other hand, the high energy density pinch plasma in DPF device makes it a multiple radiation source of ions, electron, soft and hard x-rays, and neutrons, making it useful for several applications in many different fields such as lithography, radiography, imaging, activation analysis, radioisotopes production etc. Being a source of hot dense plasma, strong shockwave, intense energetic beams and radiation, etc, the DPF device, additionally, shows tremendous potential for applications in plasma nanoscience and plasma nanotechnology. In the present paper, the key features of plasma focus device are critically discussed to understand the novelties and opportunities that this device offers in processing and synthesis of nanophase materials using, both, the top-down and bottom-up approach. The results of recent key experimental investigations performed on (i) the processing and modification of bulk target substrates for phase change, surface reconstruction and nanostructurization, (ii) the nanostructurization of PLD grown magnetic thin films, and (iii) direct synthesis of nanostructured (nanowire, nanosheets and nanoflowers) materials using anode target material ablation, ablated plasma and background reactive gas based synthesis and purely gas phase synthesis of various different types of

  1. Dense Plasma Focus With High Energy Helium Beams for Radiological Source Replacement

    NASA Astrophysics Data System (ADS)

    Schmidt, Andrea; Ellsworth, Jennifer; Falabella, Steve; Link, Anthony; Rusnak, Brian; Sears, Jason; Tang, Vincent

    2014-10-01

    A dense plasma focus (DPF) is a compact accelerator that can produce intense high energy ion beams (multiple MeV). It could be used in place of americium-beryllium (AmBe) neutron sources in applications such as oil well logging if optimized to produce high energy helium beams. AmBe sources produce neutrons when 5.5 MeV alphas emitted from the Am interact with the Be. However, due to the very small alpha-Be cross section for alphas <2 MeV, an AmBe source replacement would have to accelerate ~0.15 μC of He to 2 + MeV in order to produce 107 neutrons per pulse. We are using our particle in cell (PIC) model in LSP of a 4 kJ dense plasma focus discharge to guide the optimization of a compact DPF for the production of high-energy helium beam. This model is fluid for the run-down phase, and then transitions to fully kinetic prior to the pinch in order to include kinetic effects such as ion beam formation and anomalous resistivity. An external pulsed-power driver circuit is used at the anode-cathode boundary. Simulations will be benchmarked to He beam measurements using filtered and time-of-flight Faraday cup diagnostics. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work supported by US DOE/NA-22 Office of Non-proliferation Research and Development. Computing support for this work came from the LLNL Institutional Computing Grand Challenge program.

  2. Nonadiabtic electron dynamics in densely quasidegenerate states in highly excited boron cluster.

    PubMed

    Yonehara, Takehiro; Takatsuka, Kazuo

    2016-04-28

    Following the previous study on nonadiabatic reaction dynamics including boron clusters [T. Yonehara and K. Takatsuka, J. Chem. Phys. 137, 22A520 (2012)], we explore deep into highly excited electronic states of the singlet boron cluster (B12) to find the characteristic features of the densely quasi-degenerate electronic state manifold, which undergo very frequent nonadiabatic transitions and thereby intensive electronic state mixing among very many of the relevant states. So much so, isolating the individual adiabatic states and tracking the expected potential energy surfaces both lose the physical sense. This domain of molecular situation is far beyond the realm of the Born-Oppenheimer approximation. To survey such a violent electronic state-mixing, we apply a method of nonadiabatic electron wavepacket dynamics, the semiclassical Ehrenfest method. We have tracked those electron wavepackets and found the electronic state mixing looks like an ultrafast diffusion in the Hilbert space, which results in huge fluctuation. Furthermore, due to such a violent mixing, the quantum phases associated with the electronic states are swiftly randomized, and consequently the coherence among the electronic states are lost quickly. Besides, these highly excited states are mostly of highly poly-radical nature, even in the spin singlet manifold and the number of radicals amounts up to 10 electrons in the sense of unpaired electrons. Thus the electronic states are summarized to be poly-radical and decoherent with huge fluctuation in shorter time scales of vibrational motions. The present numerical study sets a theoretical foundation for unknown molecular properties and chemical reactivity of such densely quasi-degenerate chemical species. PMID:27131547

  3. Nonadiabtic electron dynamics in densely quasidegenerate states in highly excited boron cluster

    NASA Astrophysics Data System (ADS)

    Yonehara, Takehiro; Takatsuka, Kazuo

    2016-04-01

    Following the previous study on nonadiabatic reaction dynamics including boron clusters [T. Yonehara and K. Takatsuka, J. Chem. Phys. 137, 22A520 (2012)], we explore deep into highly excited electronic states of the singlet boron cluster (B12) to find the characteristic features of the densely quasi-degenerate electronic state manifold, which undergo very frequent nonadiabatic transitions and thereby intensive electronic state mixing among very many of the relevant states. So much so, isolating the individual adiabatic states and tracking the expected potential energy surfaces both lose the physical sense. This domain of molecular situation is far beyond the realm of the Born-Oppenheimer approximation. To survey such a violent electronic state-mixing, we apply a method of nonadiabatic electron wavepacket dynamics, the semiclassical Ehrenfest method. We have tracked those electron wavepackets and found the electronic state mixing looks like an ultrafast diffusion in the Hilbert space, which results in huge fluctuation. Furthermore, due to such a violent mixing, the quantum phases associated with the electronic states are swiftly randomized, and consequently the coherence among the electronic states are lost quickly. Besides, these highly excited states are mostly of highly poly-radical nature, even in the spin singlet manifold and the number of radicals amounts up to 10 electrons in the sense of unpaired electrons. Thus the electronic states are summarized to be poly-radical and decoherent with huge fluctuation in shorter time scales of vibrational motions. The present numerical study sets a theoretical foundation for unknown molecular properties and chemical reactivity of such densely quasi-degenerate chemical species.

  4. Temperature controlled high voltage regulator

    DOEpatents

    Chiaro, Jr., Peter J.; Schulze, Gerald K.

    2004-04-20

    A temperature controlled high voltage regulator for automatically adjusting the high voltage applied to a radiation detector is described. The regulator is a solid state device that is independent of the attached radiation detector, enabling the regulator to be used by various models of radiation detectors, such as gas flow proportional radiation detectors.

  5. High temperature electronic gain device

    DOEpatents

    McCormick, J. Byron; Depp, Steven W.; Hamilton, Douglas J.; Kerwin, William J.

    1979-01-01

    An integrated thermionic device suitable for use in high temperature, high radiation environments. Cathode and control electrodes are deposited on a first substrate facing an anode on a second substrate. The substrates are sealed to a refractory wall and evacuated to form an integrated triode vacuum tube.

  6. High temperature lightweight foamed cements

    DOEpatents

    Sugama, Toshifumi.

    1989-10-03

    Cement slurries are disclosed which are suitable for use in geothermal wells since they can withstand high temperatures and high pressures. The formulation consists of cement, silica flour, water, a retarder, a foaming agent, a foam stabilizer, and a reinforcing agent. A process for producing these cements is also disclosed. 3 figs.

  7. High temperature lightweight foamed cements

    DOEpatents

    Sugama, Toshifumi

    1989-01-01

    Cement slurries are disclosed which are suitable for use in geothermal wells since they can withstand high temperatures and high pressures. The formulation consists of cement, silica flour, water, a retarder, a foaming agent, a foam stabilizer, and a reinforcing agent. A process for producing these cements is also disclosed.

  8. High temperature Seebeck coefficient metrology

    SciTech Connect

    Martin, J.; Tritt, T.; Uher, C.

    2010-12-15

    We present an overview of the challenges and practices of thermoelectric metrology on bulk materials at high temperature (300 to 1300 K). The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential property measurement for evaluating the potential performance of novel thermoelectric materials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at high temperature. This has led to the implementation of nonideal practices that have further complicated the confirmation of reported high ZT materials. To ensure meaningful interlaboratory comparison of data, thermoelectric measurements must be reliable, accurate, and consistent. This article will summarize and compare the relevant measurement techniques and apparatus designs required to effectively manage uncertainty, while also providing a reference resource of previous advances in high temperature thermoelectric metrology.

  9. Gallium phosphide high temperature diodes

    NASA Technical Reports Server (NTRS)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  10. High temperature alkali corrosion of dense SiC and Si{sub 3}N{sub 4} coated with CMZP and Mg-DOPED Al{sub 2}TiO{sub 5} in coal gas. Quarterly progress report No. 6, October 1, 1995--December 31, 1995

    SciTech Connect

    Yang, S.; Brown, J.J.

    1995-12-31

    High temperature alkali corrosion has been known to cause premature failure of ceramic components used in advanced high temperature coal combustion systems such as coal gasification and clean-up, coal fired gas turbines, and high efficiency heat engines. Non-oxide ceramics, such as SiC and Si{sub 3}N{sub 4}, are applied in HITAF systems for their well-known and desirable high temperature thermal and mechanical properties. However, these materials are prone to rapid corrosion under some types of high temperature coal combustion conditions. The objective of this research is to apply CMZP and Mg- Al{sub 2}TiO{sub 5} as coatings to SiC to improve corrosion resistance under coal combustion atmospheres as well as to improve high temperature mechanical properties. The research will not only develop and characterize CMZP and Mg-Al{sub 2}TiO{sub 5} coatings but will also strive to expand the existing knowledge of the mechanism of coal combustion corrosion of SiC in the temperature range of 1000- 4000{degrees}C.

  11. Temperature optimization of high con

    NASA Astrophysics Data System (ADS)

    Sabry, M.

    2016-06-01

    Active cooling is essential for solar cells operating under high optical concentration ratios. A system comprises four solar cells that are in thermal contact on top of a copper tube is proposed. Water is flowing inside the tube in order to reduce solar cells temperature for increasing their performance. Computational Fluid Dynamics (CFD) simulation of such system has been performed in order to investigate the effect of water flow rate, tube internal diameter, and convective heat transfer coefficient on the temperature of the solar cells. It is found that increasing convective heat transfer coefficient has a significant effect on reducing solar cells temperatures operating at low flow rates and high optical concentration ratios. Also, a further increase of water flow rate has no effect on reducing cells temperatures.

  12. Detection of arbitrarily large dynamic ground motions with a dense high-rate GPS network

    NASA Astrophysics Data System (ADS)

    Bock, Yehuda; Prawirodirdjo, Linette; Melbourne, Timothy I.

    2004-03-01

    We describe the detection of teleseismic surface waves from the 3 November 2002 Mw 7.9 Denali fault earthquake in Alaska with a dense network of 1 Hz GPS stations in southern California, about 3900 km from the event. Relative horizontal displacements with amplitudes in excess of 15 mm and duration of 700 seconds agree with integrated velocities recorded by nearby broadband seismometers with an rms difference of 2-3 mm. The displacements are derived from independent 1 Hz instantaneous positions demonstrating that a GPS network can provide direct measurements of arbitrarily large dynamic and static ground horizontal displacements at periods longer than 1 s and amplitudes above 2 mm, with an inherent precision (signal to noise) that improves indefinitely with amplitude without clipping and in real time. High-rate, real-time GPS networks can enhance earthquake detection and seismic risk mitigation and support other applications such as intelligent transportation and civil infrastructure monitoring.

  13. Low-temperature phases of dense hydrogen and deuterium by first-principles path-integral molecular dynamics

    NASA Astrophysics Data System (ADS)

    Torrent, Marc; Geneste, Gregory

    2012-02-01

    The low-temperature phases of dense hydrogen and deuterium have been investigated using first-principles path-integral molecular dynamics, a technique that we have recently implemented in the ABINIT code and that allows to account for the quantum fluctuations of atomic nuclei. A massively parallelized scheme is applied to produce trajectories of several tens of thousands steps using a 64-atom supercell and a Trotter number of 64. The so-called phases I, II and III are studied and compared to the structures proposed in the literature. The quantum fluctuations produce configurational disorder and are shown to systematically enhance the symmetry of the system: a continuous gain of symmetry in the angular density of probability of the molecules is found from classical particles to quantum D2 and finally to quantum H2. Particular emphasis is made on the ``broken-symmetry'' phase (phase II).

  14. Containerless high-temperature calorimeter

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Nisen, D. B.; Robinson, M. B.

    1979-01-01

    Samples are heated by electron bombardment in high-temperature calorimeter that operates from 1,000 to 3,600 C yet consumes less that 100 watts at temperatures less than 2,500 C. Contamination of samples is kept to minimum by suspending them from wire in vacuum chamber. Various sample slopes such as wires, dishs, spheres, rods, or irregular bodies can be accommodated and only about 100 nq of samples are needed for accurate measurements.

  15. Bellows high temperature cycle life

    SciTech Connect

    Broyles, R.K.

    1995-11-01

    In most cases, the bellows elements in an expansion joint are separated or insulated from the hot flow stream and have an actual bellows metal temperature (ABMT) that is much lower than the flow stream temperature. However, when the bellows are externally insulated or when the expansion joint is located inside a hot vessel, the ABMT can be very high. For these situations, the effects of temperature on bellows cycle life should be carefully considered. The design equations presented in the Standards of the expansion Joint Manufacturers Association (EJMA), ASME Section 8, Division 1, and ASME B31.3 do not currently provide cycle life equations or temperature correction factors for bellows operating in the creep temperature range. Therefore, a method is proposed which is specifically tailored to bellows for the estimation of high temperature cycle life based upon available test results. Data is also presented which demonstrates the effect of temperatures above and below 800 F on the cycle life of various bellows materials.

  16. Using collective x-ray Thomson scattering to measure temperature and density of warm dense matter

    SciTech Connect

    Doeppner, T; Davis, P F; Kritcher, A L; Landen, O L; Lee, H J; Regan, S P; Glenzer, S

    2009-07-29

    Collective x-ray Thomson scattering allows measuring plasmons, i.e electron plasma oscillations (Langmuir waves). This is manifest in the appearance of spectrally up- and down-shifted spectral features in addition to the Rayleigh signal. The ratio of the up- and down-shifted signals is directly related to detailed balance, allowing to determine the plasma temperature from first principles. The spectral shift of the plasmon signals is sensitive to temperature and electron density. We discuss the experimental considerations that have to be fulfilled to observe plasmon signals with x-ray Thomson scattering. As an example, we describe an experiment that used the Cl Ly-{alpha} x-ray line at 2.96 keV to measure collective Thomson scattering from solid beryllium, isochorically heated to 18 eV. Since temperature measurement based on detailed balance is based on first principles, this method is important to validate models that, for example, calculate the static ion-ion structure factor S{sub ii}(k).

  17. High Temperature Transparent Furnace Development

    NASA Technical Reports Server (NTRS)

    Bates, Stephen C.

    1997-01-01

    This report describes the use of novel techniques for heat containment that could be used to build a high temperature transparent furnace. The primary objective of the work was to experimentally demonstrate transparent furnace operation at 1200 C. Secondary objectives were to understand furnace operation and furnace component specification to enable the design and construction of a low power prototype furnace for delivery to NASA in a follow-up project. The basic approach of the research was to couple high temperature component design with simple concept demonstration experiments that modify a commercially available transparent furnace rated at lower temperature. A detailed energy balance of the operating transparent furnace was performed, calculating heat losses through the furnace components as a result of conduction, radiation, and convection. The transparent furnace shells and furnace components were redesigned to permit furnace operation at at least 1200 C. Techniques were developed that are expected to lead to significantly improved heat containment compared with current transparent furnaces. The design of a thermal profile in a multizone high temperature transparent furnace design was also addressed. Experiments were performed to verify the energy balance analysis, to demonstrate some of the major furnace improvement techniques developed, and to demonstrate the overall feasibility of a high temperature transparent furnace. The important objective of the research was achieved: to demonstrate the feasibility of operating a transparent furnace at 1200 C.

  18. High-Temperature Optical Sensor

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

    2010-01-01

    A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

  19. High temperature current mirror amplifier

    DOEpatents

    Patterson, R.B. III.

    1984-05-22

    Disclosed is a high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg. 2 figs.

  20. "Green" High-Temperature Polymers

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1998-01-01

    PMR-15 is a processable, high-temperature polymer developed at the NASA Lewis Research Center in the 1970's principally for aeropropulsion applications. Use of fiber-reinforced polymer matrix composites in these applications can lead to substantial weight savings, thereby leading to improved fuel economy, increased passenger and payload capacity, and better maneuverability. PMR-15 is used fairly extensively in military and commercial aircraft engines components seeing service temperatures as high as 500 F (260 C), such as the outer bypass duct for the F-404 engine. The current world-wide market for PMR-15 materials (resins, adhesives, and composites) is on the order of $6 to 10 million annually.

  1. High Temperature Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    1985-01-01

    These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) characterization; (4) environmental effects; and (5) applications.

  2. High temperature superconductor current leads

    DOEpatents

    Hull, J.R.; Poeppel, R.B.

    1995-06-20

    An electrical lead is disclosed having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths. 9 figs.

  3. High temperature superconductor current leads

    DOEpatents

    Hull, John R.; Poeppel, Roger B.

    1995-01-01

    An electrical lead having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths.

  4. Segregation of Particles by Size and Density in Dense Sheared Flows: Gravity, Temperature Gradients, and Stress Partitioning

    NASA Astrophysics Data System (ADS)

    Tan, Danielle; Hill, Kimberly

    2013-11-01

    In sheared mixtures of different-sized (same density) particles modestly larger particles tend to go up (toward the free surface), and the smaller particles, down, commonly referred to as the ``Brazil-nut problem'' or ``kinetic sieving.'' If the larger particles are sufficiently denser than the smaller particles, the segregation reverses. Using theory and simulations, we have recently shown that the segregation fluxes among particles differing in size only are driven by two effects: (1) the difference between the partitioning of kinetic and contact stresses among the species in the mixture and (2) a kinetic stress gradient. Specifically, the higher granular temperature of the smaller particles segregates them downward along a kinetic stress gradient toward lower temperatures, and larger particles upward. We adapt the theory to mixtures differing in both size and density and use simulations to show that when the larger particles are sufficiently dense, the theory captures the observed segregation reversal through a reversal in the relative granular temperature born by the two species. In other words, with increasing material density, the larger particles bear increasing fractions of the local kinetic stresses, and the segregation reverses as the larger particles bear a higher fraction than their local concentration in the mixture.

  5. High resolution ALMA observations of dense molecular medium in the central regions of active galaxies

    NASA Astrophysics Data System (ADS)

    Kohno, Kotaro

    2015-08-01

    I will present recent ALMA results on the dense molecular gas in the central regions of local active galaxies, including NGC 1068, NGC 1097, and NGC 7469, hosting both AGN and circumnuclear starburst regions. Impact of X-ray radiation, outflows, and shocks from active nuclei on the physical and chemical properties of the surrouding dense molecular medium will be discussed.

  6. High temperature alkali corrosion of dense SiC and Si{sub 3}N{sub 4} coated with CMZP and Mg-doped Al{sub 2}TiO{sub 5} in coal gas. Quarterly progress report No. 10, October 1, 1996--December 31, 1996

    SciTech Connect

    Thierry, N.; Brown, J.J.

    1997-01-15

    In high temperature engineering applications, commercially available silicon nitride non-oxide ceramics have retained special attention because of their superior thermal, mechanical, and chemical properties. These properties mainly include a high fracture strength and toughness, a low coefficient of thermal expansion relative to other ceramics, good thermal shock resistance, and good chemical stability. With silicon carbide, silicon nitride was the second material selected for heat exchangers in the High Temperature Advanced Furnace being developed under the DOE Combustion 2000 program. Their potential use in heat exchangers is, however, limited in time since both materials corrode severely in high temperature coal combustion atmospheres containing alkali compounds. Thus, this research will first focus on enhancing the performance of Si{sub 3}N{sub 4} ceramics by coating them with alkali corrosion resistant materials such as CMZP and Mg-doped Al{sub 2}TiO{sub 5} oxide ceramics.

  7. High pressure behaviour and elastic properties of a dense inorganic-organic framework.

    PubMed

    Feng, Guoqiang; Jiang, Xingxing; Wei, Wenjuan; Gong, Pifu; Kang, Lei; Li, Zhihua; Li, Yanchun; Li, Xiaodong; Wu, Xiang; Lin, Zheshuai; Li, Wei; Lu, Peixiang

    2016-03-14

    The high pressure behaviour of a cubic dense inorganic-organic framework [DABCOH2(2+)][K(ClO4)3] (DABCOH2(2+) = diazabicyclo[2.2.2]octane-1,4-diium) has been systematically studied via synchrotron X-ray powder diffraction, over the range of 0-3.12 GPa. The framework [DABCOH2(2+)][K(ClO4)3] shows a more rigid response, with a bulk modulus of 30(1) GPa and an axial compressibility of 7.6(4) × 10(-3) GPa(-1), compared with ZIF-8 and the dense hybrid solar cell perovskite CH3NH3PbI3. Density functional theory calculations reveal that the structural change in [DABCOH2(2+)][K(ClO4)3] is attributed to the contraction of the KO12 polyhedra, which consequently results in the rotation of the perchlorate linkers and synergistic movement of the DABCOH2(2+) guest. Further extensive theoretical calculations of full elastic tensors give full mapping of the Young's moduli, shear moduli and Poisson's ratios of [DABCOH2(2+)][K(ClO4)3], which are in the range of 31.6-36.6, 12.3-14.6 GPa and 0.2-0.32, respectively. The Young's and shear moduli of [DABCOH2(2+)][K(ClO4)3] are larger than those of cubic MOF-5, ZIF-8 and CH3NH3PbI3. In addition, the narrow range of Poisson's ratios in [DABCOH2(2+)][K(ClO4)3] indicates its very isotropic nature in response to biaxial stress. PMID:26613418

  8. Expected satiation after repeated consumption of low- or high-energy-dense soup.

    PubMed

    Hogenkamp, Pleunie S; Brunstrom, Jeffrey M; Stafleu, Annette; Mars, Monica; de Graaf, Cees

    2012-07-14

    We investigated whether repeated consumption of a low-energy-dense (LED; 208 kJ/100 g) or high-energy-dense (HED; 645 kJ/100 g) soup modifies expectations relating to the satiating capacity of the food, and its subsequent intake. In study 1, participants consumed either a novel-flavoured LED (n 32; 21 (SD 1·6) years, BMI 21·4 (SD 1·6) kg/m(2)) or HED soup (n 32; 21 (SD 1·6) years, BMI 21·3 (SD 1·7) kg/m(2)). Soup was served in a fixed amount on days 1-4 and ad libitum on day 5. 'Expected satiation' was measured on days 1, 2 and 5. Expected satiation did not change after repeated consumption of the LED or HED soup. Ad libitum intake did not differ between the LED (461 (SD 213) g) and HED soup (391 (SD 164) g). Only on day 1, expected satiation was higher for the HED soup than for the LED soup (P = 0·03), suggesting a role for sensory attributes in expected satiation. In study 2, thirty participants (21 (SD 1·6) years, BMI 21·3 (SD 1·7) kg/m(2)) performed a single measurement of expected satiation of the LED and HED soup, and four commercially available types of soup. Ratings on sensory attributes were associated with expected satiation. Results on expected satiation coincided with those of study 1. Thickness and intensity of taste were independently associated with expected satiation. Expectations may initially rely on sensory attributes and previous experiences, and are not easily changed.

  9. Uniform temperature profile for a dense array CPV receiver under non uniform illumination profile

    NASA Astrophysics Data System (ADS)

    Riera, Sara; Barrau, Jérôme; Perona, Arnaud; Dollet, Alain; Rosell, Joan I.; Fréchette, Luc

    2014-09-01

    Previous experimental and numerical studies of hybrid cooling devices for CPV receivers were developed under uniform illumination profile conditions; but literature review shows that this uniformity assumption is difficult to satisfy in real conditions. This investigation presents the design and the validation of a hybrid cooling device able to tailor its local heat extraction capacity to 2D illumination profiles in order to provide a uniform temperature profile of the PV receiver as well as a low global thermal resistance coefficient. The inputs of the design procedure are the solar concentration, the coolant flow rate and its inlet temperature. As the illumination profile is 2D dependent, a matrix of pin fins is implemented and a hybrid Jet Impingement /Matrix of Pin Fins cooling device is experimentally tested and compared to a hybrid Jet Impingement / Microchannels cooling device developed previously. The results demonstrate similar performances for both designs. Furthermore, in contrast to the cooling scheme using longitudinal fins, the distribution of the pin fins can be tailored, in two dimensions, to the local need of heat extraction capacity.

  10. High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems

    SciTech Connect

    Turnquist, Norman; Qi, Xuele; Raminosoa, Tsarafidy; Salas, Ken; Samudrala, Omprakash; Shah, Manoj; Van Dam, Jeremy; Yin, Weijun; Zia, Jalal

    2013-12-20

    This report summarizes the progress made during the April 01, 2010 – December 30, 2013 period under Cooperative Agreement DE-EE0002752 for the U.S. Department of Energy entitled “High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems.” The overall objective of this program is to advance the technology for well fluids lifting systems to meet the foreseeable pressure, temperature, and longevity needs of the Enhanced Geothermal Systems (EGS) industry for the coming ten years. In this program, lifting system requirements for EGS wells were established via consultation with industry experts and site visits. A number of artificial lift technologies were evaluated with regard to their applicability to EGS applications; it was determined that a system based on electric submersible pump (ESP) technology was best suited to EGS. Technical barriers were identified and a component-level technology development program was undertaken to address each barrier, with the most challenging being the development of a power-dense, small diameter motor that can operate reliably in a 300°C environment for up to three years. Some of the targeted individual component technologies include permanent magnet motor construction, high-temperature insulation, dielectrics, bearings, seals, thrust washers, and pump impellers/diffusers. Advances were also made in thermal management of electric motors. In addition to the overall system design for a full-scale EGS application, a subscale prototype was designed and fabricated. Like the full-scale design, the subscale prototype features a novel “flow-through-the-bore” permanent magnet electric motor that combines the use of high temperature materials with an internal cooling scheme that limits peak internal temperatures to <330°C. While the full-scale high-volume multi-stage pump is designed to lift up to 80 kg/s of process water, the subscale prototype is based on a production design that can pump 20 kg/s and has been modified

  11. Nuclear quantum effects on the high pressure melting of dense lithium

    SciTech Connect

    Feng, Yexin; Chen, Ji; Alfè, Dario; Li, Xin-Zheng Wang, Enge

    2015-02-14

    Using a self-developed combination of the thermodynamic integration and the ab initio path-integral molecular dynamics methods, we quantitatively studied the influence of nuclear quantum effects (NQEs) on the melting of dense lithium at 45 GPa. We find that although the NQEs significantly change the free-energies of the competing solid and liquid phases, the melting temperature (T{sub m}) is lowered by only ∼15 K, with values obtained using both classical and quantum nuclei in close proximity to a new experiment. Besides this, a substantial narrowing of the solid/liquid free-energy differences close to T{sub m} was observed, in alignment with a tendency that glassy states might form upon rapid cooling. This tendency was demonstrated by the dynamics of crystallization in the two-phase simulations, which helps to reconcile an important conflict between two recent experiments. This study presents a simple picture for the phase diagram of lithium under pressure. It also indicates that claims on the influence of NQEs on phase diagrams should be carefully made and the method adopted offers a robust solution for such quantitative analyses.

  12. A solar high temperature kiln

    NASA Astrophysics Data System (ADS)

    Huettenhoelscher, N.; Bergmann, K.

    1981-11-01

    The feasibility of using solar energy in developing countries for baking ceramic construction materials was investigated. The solar high temperature kiln is described. It uses two parabolic concentrators which direct available radiation into the baking chamber. The Sun tracker has only one axis. Preliminary test results with the prototype kiln were satisfactory.

  13. High temperature turbine engine structure

    DOEpatents

    Boyd, Gary L.

    1991-01-01

    A high temperature turbine engine includes a rotor portion having axially stacked adjacent ceramic rotor parts. A ceramic/ceramic joint structure transmits torque between the rotor parts while maintaining coaxial alignment and axially spaced mutually parallel relation thereof despite thermal and centrifugal cycling.

  14. High-Temperature Vibration Damper

    NASA Technical Reports Server (NTRS)

    Clarke, Alan; Litwin, Joel; Krauss, Harold

    1987-01-01

    Device for damping vibrations functions at temperatures up to 400 degrees F. Dampens vibrational torque loads as high as 1,000 lb-in. but compact enough to be part of helicopter rotor hub. Rotary damper absorbs energy from vibrating rod, dissipating it in turbulent motion of viscous hydraulic fluid forced by moving vanes through small orifices.

  15. Herschel Dust Temperatures of High-Mass Star Forming Cores

    NASA Astrophysics Data System (ADS)

    Jackson, James

    We request NASA ADAP support to infer the evolutionary state, luminosities, and masses of 3,000 star-forming dense molecular cores using Herschel Hi-GAL data. The target cores are selected from the 870 μm ATLASGAL survey to host the early stages of high-mass star formation and to span the complete range of their early evolutionary stages. All 3,000 of these cores will be mapped in the Millimeter Astronomy Legacy Team 90 GHz Survey (MALT90), a new project designed to simultaneously image 16 molecular lines near 90 GHz. The dust temperatures derived from the Hi-GAL data will provide the key diagnostic of the evolutionary phase, as the cores evolve due to heating by the embedded young stars from the earliest cold "starless cores," to intermediate temperature "protostellar cores," and finally on to "hot cores" and H II regions. We will correlate the evolutionary state indicated by the Hi-GAL dust temperatures with the chemical and kinematic information supplied by the MALT 90 molecular line survey. Moreover, since MALT 90 data provides kinematic distances, the Hi-GAL submm/FIR spectral energy distributions will also provide the luminosity and mass distributions of dense cores. This project will allow for the first time a complete and robust characterization of the physical evolution of dense cores. Since this project studies the formation of high-mass stars, it bears directly on NASA's Origins theme.

  16. High temperature, high power piezoelectric composite transducers.

    PubMed

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-08-08

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  17. High Temperature, High Power Piezoelectric Composite Transducers

    PubMed Central

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, StewarT.

    2014-01-01

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

  18. High temperature, high power piezoelectric composite transducers.

    PubMed

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-01-01

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

  19. Highly Dense Cu Nanowires for Low-Overpotential CO2 Reduction.

    PubMed

    Raciti, David; Livi, Kenneth J; Wang, Chao

    2015-10-14

    Electrochemical reduction of CO2, an artificial way of carbon recycling, represents one promising solution for energy and environmental sustainability. However, it is challenged by the lack of active and selective catalysts. Here, we report a two-step synthesis of highly dense Cu nanowires as advanced electrocatalysts for CO2 reduction. CuO nanowires were first grown by oxidation of Cu mesh in air and then reduced by either annealing in the presence of hydrogen or applying a cathodic electrochemical potential to produce Cu nanowires. The two reduction methods generated Cu nanowires with similar dimensions but distinct surface structures, which have provided an ideal platform for comparative studies of the effect of surface structure on the electrocatalytic properties. In particular, the Cu nanowires generated by electrochemical reduction were highly active and selective for CO2 reduction, requiring an overpotential of only 0.3 V to reach 1 mA/cm(2) electrode current density and achieving Faradaic efficiency toward CO as high as ∼60%. Our work has advanced the understanding of the structure-property relationship of Cu-based nanocatalysts, which could be valuable for the further development of advanced electrocatalytic materials for CO2 reduction.

  20. Laser rapid forming technology of high-performance dense metal components with complex structure

    NASA Astrophysics Data System (ADS)

    Huang, Weidong; Chen, Jing; Li, Yanming; Lin, Xin

    2005-01-01

    Laser rapid forming (LRF) is a new and advanced manufacturing technology that has been developed on the basis of combining high power laser cladding technology with rapid prototyping (RP) to realize net shape forming of high performance dense metal components without dies. Recently we have developed a set of LRF equipment. LRF experiments were carried out on the equipment to investigate the influences of processing parameters on forming characterizations systematically with the cladding powder materials as titanium alloys, superalloys, stainless steel, and copper alloys. The microstructure of laser formed components is made up of columnar grains or columnar dendrites which grow epitaxially from the substrate since the solid components were prepared layer by layer additionally. The result of mechanical testing proved that the mechanical properties of laser formed samples are similar to or even over that of forging and much better than that of casting. It is shown in this paper that LRF technology is providing a new solution for some difficult processing problems in the high tech field of aviation, spaceflight and automobile industries.

  1. High-temperature containerless calorimeter

    NASA Technical Reports Server (NTRS)

    Robinson, M. B.; Lacy, L. L.

    1985-01-01

    A high-temperature (greater than 1500 K) containerless calorimeter is described and its usefulness demonstrated. The calorimeter uses the technique of omnidirectional electron bombardment of pendant drops to achieve an isothermal test environment. The small heat input into the sample (i.e., 15-50 W) can be controlled and measured. The apparatus can be used to determine the total hemispherical emissivity, specific heat, heat of fusion, surface tension, and equilibrium melting temperature of small molten drops in the temperature range of 1500 to 3500 K. The total hemispherical emissivity and specific heat of pure niobium and two alloys of niobium-germanium have been measured in the temperature range of 1700 to 2400 K. As reported in the literature, the total hemispherical emissivity varied as a function of temperature. However, specific heat values for both the pure metal and alloys seem to be independent of temperature. Specific heat for the liquid alloy phase was also measured and compared to the solid phase.

  2. Solute strengthening at high temperatures

    NASA Astrophysics Data System (ADS)

    Leyson, G. P. M.; Curtin, W. A.

    2016-08-01

    The high temperature behavior of solute strengthening has previously been treated approximately using various scaling arguments, resulting in logarithmic and power-law scalings for the stress-dependent energy barrier Δ E(τ ) versus stress τ. Here, a parameter-free solute strengthening model is extended to high temperatures/low stresses without any a priori assumptions on the functional form of Δ E(τ ) . The new model predicts that the well-established low-temperature, with energy barrier Δ {{E}\\text{b}} and zero temperature flow stress {τy0} , transitions to a near-logarithmic form for stresses in the regime 0.2<τ /{τy0}≤slant 0.5 and then transitions to a power-law form at even lower stresses τ /{τy0}<0.03 . Δ {{E}\\text{b}} and {τy0} remains as the reference energy and stress scales over the entire range of stresses. The model is applied to literature data on solution strengthening in Cu alloys and captures the experimental results quantitatively and qualitatively. Most importantly, the model accurately captures the transition in strength from the low-temperature to intermediate-temperature and the associated transition for the activation volume. Overall, the present analysis unifies the different qualitative models in the literature and, when coupled with the previous parameter-free solute strengthening model, provides a single predictive model for solute strengthening as a function of composition, temperature, and strain rate over the full range of practical utility.

  3. High temperature strain gage evaluation

    NASA Technical Reports Server (NTRS)

    Gonzalez, J. I.

    1977-01-01

    The structural thermal test of an advanced ramjet missile section required strain measurements as high as 922 K (1200 F). Since there is relatively little experience in the use of strain gages above the 700-755 K (800-900 F) level, a program was initiated to select and evaluate the best available gage. Candidate gages suitable for measurements up to 922 K (1200 F) were selected. This involved the determination of their operating characteristics, availability, cost, installation aspects, etc. The evaluation involved the following tests: strain as a function of load at room temperature and apparent strain as a function of temperature.

  4. High temperature sorbents for oxygen

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor)

    1994-01-01

    A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C comprising a porous alumina silicate support, such as zeolite, containing from 1 to 10 percent by weight of ion exchanged transition metal, such as copper or cobalt ions, and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum is described. The activation temperature, oxygen sorption, and reducibility are all improved by the presence of the platinum activator.

  5. High Temperature Sorbents for Oxygen

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K. (Inventor)

    1996-01-01

    A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C is introduced. The sorbent comprises a porous alumina silicate support such as zeolite containing from 1 to 10 percent by weight of ion exchanged transition metal such as copper or cobalt ions and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum. The activation temperature, oxygen sorption and reducibility are all improved by the presence of the platinum activator.

  6. Shape-engineerable and highly densely packed single-walled carbon nanotubes and their application as super-capacitor electrodes.

    PubMed

    Futaba, Don N; Hata, Kenji; Yamada, Takeo; Hiraoka, Tatsuki; Hayamizu, Yuhei; Kakudate, Yozo; Tanaike, Osamu; Hatori, Hiroaki; Yumura, Motoo; Iijima, Sumio

    2006-12-01

    We present a rational and general method to fabricate a high-densely packed and aligned single-walled carbon-nanotube (SWNT) material by using the zipping effect of liquids to draw tubes together. This bulk carbon-nanotube material retains the intrinsic properties of individual SWNTs, such as high surface area, flexibility and electrical conductivity. By controlling the fabrication process, it is possible to fabricate a wide range of solids in numerous shapes and structures. This dense SWNT material is advantageous for numerous applications, and here we demonstrate its use as flexible heaters as well as supercapacitor electrodes for compact energy-storage devices.

  7. High temperature thermoelectric energy conversion

    NASA Technical Reports Server (NTRS)

    Wood, Charles

    1987-01-01

    The theory and current status of materials research for high-temperature thermoelectric energy conversion are reviewed. Semiconductors are shown to be the preferred class of materials for this application. Optimization of the figure of merit of both broadband and narrow-band semiconductors is discussed as a function of temperature. Phonon scattering mechanisms are discussed, and basic material guidelines are given for reduction of thermal conductivity. Two general classes of materials show promise for high temperature figure of merit (Z) values, namely the rare earth chalcogenides and the boron-rich borides. The electronic transport properties of the rare earth chalcogenides are explicable on the basis of degenerate or partially degenerate n-type semiconductors. Boron and boron-rich borides exhibit p-type hopping conductivity, with detailed explanations proposed for the transport differing from compound to compound. Some discussion is presented on the reasons for the low thermal conductivities in these materials. Also, ZTs greater than one appear to have been realized at high temperature in many of these compounds.

  8. High Temperature Transfer Molding Resins

    NASA Technical Reports Server (NTRS)

    Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

    2000-01-01

    High temperature resins containing phenylethynyl groups that are processable by transfer molding have been prepared. These phenylethynyl containing oligomers were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynlphthalic anhydride in glacial acetic acid to form a mixture of imide compounds in one step. This synthetic approach is advantageous since the products are a mixture of compounds and consequently exhibit a relatively low melting temperature. In addition, these materials exhibit low melt viscosities which are stable for several hours at 210-275 C, and since the thermal reaction of the phenylethynyl group does not occur to any appreciable extent at temperatures below 300 C, these materials have a broad processing window. Upon thermal cure at approximately 300-350 C, the phenylethynyl groups react to provide a crosslinked resin system. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

  9. High temperature seal test rig

    NASA Technical Reports Server (NTRS)

    Addy, Harold E., Jr.

    1994-01-01

    The High Temperature Seals Test Rig Program at NASA's Lewis Research Center is a joint effort involving three separate federal government agencies. Testing has been underway at Lewis in this test rig since April, 1993. The rig was designed to run tests at temperatures to 800 F at pressures to 200 psia or at temperatures to 1300 to 1500 F at pressures to 65 psia. It was designed to run at speeds of up to 50,000 rpm which, for a 5.1 inch diameter disk, is a surface speed of about 1100 ft./sec. The rig was designed to allow easy replacement of the disks as well as the seals such that different disk materials and coatings may be tested.

  10. High-temperature battery calorimeter

    SciTech Connect

    Hansen, L.D.; Hart, R.H.; Chen, D.M.; Gibbard, H.F.

    1982-04-01

    A battery calorimeter was built for the measurement of thermal energy generation of high-temperature lithium--aluminum/iron sulfide battery cells, which are under development for electric vehicle propulsion and other energy storage applications. The calorimeter was designed with a temperature range of 400 /sup 0/--500 /sup 0/C, a detection limit of 1 mW, and an upper limit of heat flow of 50 W. The results of measurements on 200-Ah LiAl/FeS cells were in excellent agreement with the predictions of thermodynamic calculations based on precise measurements of the total cell polarization and the temperature coefficient of the emf. Details of the construction and operation principles of this calorimeter are given.

  11. Dense all-optical WDM-SCM technology for high-speed computer interconnects

    NASA Astrophysics Data System (ADS)

    Ih, Charles S.; Tian, Rongsheng; Zhou, H. X.; Xia, Xiang-Gen

    1993-07-01

    We describe a dense and flexible all optical multi-channel communication system for high speed computer interconnects. The system can provide 10 Gb/s for each individual node with a total system capacity to 250 Gb/s using currently available technologies. The system capacity can be scaled to 1 Tb/s using optical amplifiers with a broader bandwidth and higher modulations. The system is based on the multi-beam (heterodyne) modulator (MBM) recently demonstrated in our laboratory and other current technologies in tunable laser arrays and acousto-optical tunable filter (AOTF). Each MBM automatically forms a high frequency microwave sub-carrier multiplexing (SCM) with sub-carrier frequency to tens of GHz. A MBM with sub-carriers at 17 and 21 GHz has already been demonstrated and can be scaled to higher frequencies by using a higher frequency detector. Each SCM group may consist of up to 10 one-Gb/s channels and occupies only 1 nm spectral width. Therefore we can form a conventional WDM with 25 divisions within the bandwidth of commercially available optical amplifiers.

  12. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media.

    PubMed

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

    2012-04-20

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles' performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications.

  13. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media.

    PubMed

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

    2012-04-20

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles' performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications. PMID:22456180

  14. High temperature alkali corrosion of dense SiC and Si{sub 3}N{sub 4} coated with CMZP and Mg-doped Al{sub 2}TiO{sub 5} in coal gas. Quarterly progress report No. 7, January 1, 1996--March 31, 1996

    SciTech Connect

    Yang, Shaokai; Brown, J.J.

    1996-03-31

    Objective is to apply CMZP and Mg-Al{sub 2}TiO{sub 5} as coatings to SiC to improve corrosion resistance under coal combustion atmospheres as well as to improve high temperature mechanical properties. The research will also study the mechanism of coal combustion corrosion of SiC at 1000-1400 C. 16 figs, 8 tabs.

  15. NSTX High Temperature Sensor Systems

    SciTech Connect

    B.McCormack; H.W. Kugel; P. Goranson; R. Kaita; et al

    1999-11-01

    The design of the more than 300 in-vessel sensor systems for the National Spherical Torus Experiment (NSTX) has encountered several challenging fusion reactor diagnostic issues involving high temperatures and space constraints. This has resulted in unique miniature, high temperature in-vessel sensor systems mounted in small spaces behind plasma facing armor tiles, and they are prototypical of possible high power reactor first-wall applications. In the Center Stack, Divertor, Passive Plate, and vessel wall regions, the small magnetic sensors, large magnetic sensors, flux loops, Rogowski Coils, thermocouples, and Langmuir Probes are qualified for 600 degrees C operation. This rating will accommodate both peak rear-face graphite tile temperatures during operations and the 350 degrees C bake-out conditions. Similar sensor systems including flux loops, on other vacuum vessel regions are qualified for 350 degrees C operation. Cabling from the sensors embedded in the graphite tiles follows narrow routes to exit the vessel. The detailed sensor design and installation methods of these diagnostic systems developed for high-powered ST operation are discussed.

  16. High temperature two component explosive

    DOEpatents

    Mars, James E.; Poole, Donald R.; Schmidt, Eckart W.; Wang, Charles

    1981-01-01

    A two component, high temperature, thermally stable explosive composition comprises a liquid or low melting oxidizer and a liquid or low melting organic fuel. The oxidizer and fuel in admixture are incapable of substantial spontaneous exothermic reaction at temperatures on the order of 475.degree. K. At temperatures on the order of 475.degree. K., the oxidizer and fuel in admixture have an activation energy of at least about 40 kcal/mol. As a result of the high activation energy, the preferred explosive compositions are nondetonable as solids at ambient temperature, and become detonable only when heated beyond the melting point. Preferable oxidizers are selected from alkali or alkaline earth metal nitrates, nitrites, perchlorates, and/or mixtures thereof. Preferred fuels are organic compounds having polar hydrophilic groups. The most preferred fuels are guanidinium nitrate, acetamide and mixtures of the two. Most preferred oxidizers are eutectic mixtures of lithium nitrate, potassium nitrate and sodium nitrate, of sodium nitrite, sodium nitrate and potassium nitrate, and of potassium nitrate, calcium nitrate and sodium nitrate.

  17. High temperature structural sandwich panels

    NASA Astrophysics Data System (ADS)

    Papakonstantinou, Christos G.

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400°C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several

  18. Motor for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Roopnarine (Inventor)

    2013-01-01

    A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.

  19. High Temperature Heat Exchanger Project

    SciTech Connect

    Anthony E. Hechanova, Ph.D.

    2008-09-30

    The UNLV Research Foundation assembled a research consortium for high temperature heat exchanger design and materials compatibility and performance comprised of university and private industry partners under the auspices of the US DOE-NE Nuclear Hydrogen Initiative in October 2003. The objectives of the consortium were to conduct investigations of candidate materials for high temperature heat exchanger componets in hydrogen production processes and design and perform prototypical testing of heat exchangers. The initial research of the consortium focused on the intermediate heat exchanger (located between the nuclear reactor and hydrogen production plan) and the components for the hydrogen iodine decomposition process and sulfuric acid decomposition process. These heat exchanger components were deemed the most challenging from a materials performance and compatibility perspective

  20. High pressure and high temperature apparatus

    DOEpatents

    Voronov, Oleg A.

    2005-09-13

    A design for high pressure/high temperature apparatus and reaction cell to achieve .about.30 GPa pressure in .about.1 cm volume and .about.100 GPa pressure in .about.1 mm volumes and 20-5000.degree. C. temperatures in a static regime. The device includes profiled anvils (28) action on a reaction cell (14, 16) containing the material (26) to be processed. The reaction cell includes a heater (18) surrounded by insulating layers and screens. Surrounding the anvils are cylindrical inserts and supporting rings (30-48) whose hardness increases towards the reaction cell. These volumes may be increased considerably if applications require it, making use of presses that have larger loading force capability, larger frames and using larger anvils.

  1. High temperature solar thermal receiver

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A design concept for a high temperature solar thermal receiver to operate at 3 atmospheres pressure and 2500 F outlet was developed. The performance and complexity of windowed matrix, tube-header, and extended surface receivers were evaluated. The windowed matrix receiver proved to offer substantial cost and performance benefits. An efficient and cost effective hardware design was evaluated for a receiver which can be readily interfaced to fuel and chemical processes or to heat engines for power generation.

  2. HIGH TEMPERATURE MICROSCOPE AND FURNACE

    DOEpatents

    Olson, D.M.

    1961-01-31

    A high-temperature microscope is offered. It has a reflecting optic situated above a molten specimen in a furnace and reflecting the image of the same downward through an inert optic member in the floor of the furnace, a plurality of spaced reflecting plane mirrors defining a reflecting path around the furnace, a standard microscope supported in the path of and forming the end terminus of the light path.

  3. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1993-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  4. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1994-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  5. High temperature turbine engine structure

    DOEpatents

    Carruthers, William D.; Boyd, Gary L.

    1992-01-01

    A high temperature ceramic/metallic turbine engine includes a metallic housing which journals a rotor member of the turbine engine. A ceramic disk-like shroud portion of the engine is supported on the metallic housing portion and maintains a close running clearance with the rotor member. A ceramic spacer assembly maintains the close running clearance of the shroud portion and rotor member despite differential thermal movements between the shroud portion and metallic housing portion.

  6. High-temperature geothermal cableheads

    SciTech Connect

    Coquat, J.A.; Eifert, R.W.

    1981-11-01

    Two high-temperature, corrosion-resistant logging cableheads which use metal seals and a stable fluid to achieve proper electrical terminations and cable-sonde interfacings are described. A tensile bar provides a calibrated yield point, and a cone assembly anchors the cable armor to the head. Electrical problems of the sort generally ascribable to the cable-sonde interface were absent during demonstration hostile-environment loggings in which these cableheads were used.

  7. High temperature catalytic membrane reactors

    SciTech Connect

    Not Available

    1990-03-01

    Current state-of-the-art inorganic oxide membranes offer the potential of being modified to yield catalytic properties. The resulting modules may be configured to simultaneously induce catalytic reactions with product concentration and separation in a single processing step. Processes utilizing such catalytically active membrane reactors have the potential for dramatically increasing yield reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity. Examples of commercial interest include hydrogenation, dehydrogenation, partial and selective oxidation, hydrations, hydrocarbon cracking, olefin metathesis, hydroformylation, and olefin polymerization. A large portion of the most significant reactions fall into the category of high temperature, gas phase chemical and petrochemical processes. Microporous oxide membranes are well suited for these applications. A program is proposed to investigate selected model reactions of commercial interest (i.e. dehydrogenation of ethylbenzene to styrene and dehydrogenation of butane to butadiene) using a high temperature catalytic membrane reactor. Membranes will be developed, reaction dynamics characterized, and production processes developed, culminating in laboratory-scale demonstration of technical and economic feasibility. As a result, the anticipated increased yield per reactor pass economic incentives are envisioned. First, a large decrease in the temperature required to obtain high yield should be possible because of the reduced driving force requirement. Significantly higher conversion per pass implies a reduced recycle ratio, as well as reduced reactor size. Both factors result in reduced capital costs, as well as savings in cost of reactants and energy.

  8. Dense plasma heating and Gbar shock formation by a high intensity flux of energetic electrons

    SciTech Connect

    Ribeyre, X.; Feugeas, J.-L.; Nicolaï, Ph.; Tikhonchuk, V. T.; Gus'kov, S.

    2013-06-15

    Process of shock ignition in inertial confinement fusion implies creation of a high pressure shock with a laser spike having intensity of the order of a few PW/cm{sup 2}. However, the collisional (Bremsstrahlung) absorption at these intensities is inefficient and a significant part of laser energy is converted in a stream of energetic electrons. The process of shock formation in a dense plasma by an intense electron beam is studied in this paper in a planar geometry. The energy deposition takes place in a fixed mass target layer with the areal density determined by the electron range. A self-similar isothermal rarefaction wave of a fixed mass describes the expanding plasma. Formation of a shock wave in the target under the pressure of expanding plasma is described. The efficiency of electron beam energy conversion into the shock wave energy depends on the fast electron energy and the pulse duration. The model is applied to the laser produced fast electrons. The fast electron energy transport could be the dominant mechanism of ablation pressure creation under the conditions of shock ignition. The shock wave pressure exceeding 1 Gbar during 200–300 ps can be generated with the electron pulse intensity in the range of 5–10 PW/cm{sup 2}. The conclusions of theoretical model are confirmed in numerical simulations with a radiation hydrodynamic code coupled with a fast electron transport module.

  9. High-energy electron radiography of microstructures in a dense material

    NASA Astrophysics Data System (ADS)

    Qi, Rong; Tian, Ye; Zhang, Guo-Qing; Bai, Ya-Feng; Zhou, Shi-Yi; Zeng, Yu-Shan; Sun, Hai-Yi; Wang, Xing-Tao; Li, Xiao-Ya; Liu, Jian-Sheng

    2016-08-01

    This study presents experimental and numerical results for the high-energy electron-beam radiography of two types of microstructures in a dense material. A copper step target with 1- and 4-mm-thick steps is irradiated by an electron beam with an energy of 150 MeV. A peak and valley structure with 285 µm width was observed in 4-mm step target experiment, as indicated by the "valley to peak" feature at the 4-mm step boundary caused by multiple scattering. In a gap-target experiment, the rate of increase of the penetrant-electron counts with a gap width of 500-900 µm grows from 1.5 to 2.5 times the background counts. Consequently, the width of the gaps can be approximately deduced from the ratio of the penetrant-electron counts combined with the peak value. The features observed in the experiment are reproduced by a Monte Carlo-FLUKE code with parameters similar to those used experimentally.

  10. High temperature polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    1987-01-01

    With the increased emphasis on high performance aircraft the need for lightweight, thermal/oxidatively stable materials is growing. Because of their ease of fabrication, high specific strength, and ability to be tailored chemically to produce a variety of mechanical and physical properties, polymers and polymer matrix composites present themselves as attractive materials for a number of aeropropulsion applications. In the early 1970s researchers at the NASA Lewis Research Center developed a highly processable, thermally stable (600 F) polyimide, PMR-15. Since that time, PMR-15 has become commercially available and has found use in military aircraft, in particular, the F-404 engine for the Navy's F/A-18 strike fighter. The NASA Lewis'contributions to high temperature polymer matrix composite research will be discussed as well as current and future directions.

  11. The fate of high redshift massive compact galaxies in dense environments

    SciTech Connect

    Kaufmann, Tobias; Mayer, Lucio; Carollo, Marcella; Feldmann, Robert; /Fermilab /Chicago U., KICP

    2012-01-01

    Massive compact galaxies seem to be more common at high redshift than in the local universe, especially in denser environments. To investigate the fate of such massive galaxies identified at z {approx} 2 we analyse the evolution of their properties in three cosmological hydrodynamical simulations that form virialized galaxy groups of mass {approx} 10{sup 13} M{sub {circle_dot}} hosting a central massive elliptical/S0 galaxy by redshift zero. We find that at redshift {approx} 2 the population of galaxies with M{sub *} > 2 x 10{sup 10} M{sub {circle_dot}} is diverse in terms of mass, velocity dispersion, star formation and effective radius, containing both very compact and relatively extended objects. In each simulation all the compact satellite galaxies have merged into the central galaxy by redshift 0 (with the exception of one simulation where one of such satellite galaxy survives). Satellites of similar mass at z = 0 are all less compact than their high redshift counterparts. They form later than the galaxies in the z = 2 sample and enter the group potential at z < 1, when dynamical friction times are longer than the Hubble time. Also, by z = 0 the central galaxies have increased substantially their characteristic radius via a combination of in situ star formation and mergers. Hence in a group environment descendants of compact galaxies either evolve towards larger sizes or they disappear before the present time as a result of the environment in which they evolve. Since the group-sized halos that we consider are representative of dense environments in the {Lambda}CDM cosmology, we conclude that the majority of high redshift compact massive galaxies do not survive until today as a result of the environment.

  12. High temperature jet fuel stabilizers

    SciTech Connect

    Yoon, E.M.; Selvaraj, L.; Stallman, J.B.

    1996-10-01

    We have previously discussed the rationale for development of jet fuels with enhanced thermal stability at temperatures above 400{degrees}C. At these temperatures we are encroaching into the so-called pyrolysis regime, where the cleavage of carbon-carbon bonds into free radicals is facile and leads to the rapid degradation of aliphatic hydrocarbons. Notwithstanding, we established that the formation of carbonaceous materials is significantly retarded in hydrocarbon mixtures containing molecules such as benzyl alcohol (BzOH). It was ascertained that BzOH acts as a hydrogen donor capping aliphatic radicals formed at temperatures > 400{degrees}C while transforming into relatively stable products. These results suggested is superior high temperature thermal stabilizers might be found among the more conventional hydrogen donors that find application in coal liquefaction and similar hydrogenation processes. Here we present the results of {open_quotes}screening{close_quotes} and kinetic studies of traditional hydrogen donors, such as tetralin, tetrahydroquinoline and the like, together with simple derivatives designed to test the importance of specific factors in the thermal stabilization of jet fuels.

  13. High temperature PEM fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jianlu; Xie, Zhong; Zhang, Jiujun; Tang, Yanghua; Song, Chaojie; Navessin, Titichai; Shi, Zhiqing; Song, Datong; Wang, Haijiang; Wilkinson, David P.; Liu, Zhong-Sheng; Holdcroft, Steven

    There are several compelling technological and commercial reasons for operating H 2/air PEM fuel cells at temperatures above 100 °C. Rates of electrochemical kinetics are enhanced, water management and cooling is simplified, useful waste heat can be recovered, and lower quality reformed hydrogen may be used as the fuel. This review paper provides a concise review of high temperature PEM fuel cells (HT-PEMFCs) from the perspective of HT-specific materials, designs, and testing/diagnostics. The review describes the motivation for HT-PEMFC development, the technology gaps, and recent advances. HT-membrane development accounts for ∼90% of the published research in the field of HT-PEMFCs. Despite this, the status of membrane development for high temperature/low humidity operation is less than satisfactory. A weakness in the development of HT-PEMFC technology is the deficiency in HT-specific fuel cell architectures, test station designs, and testing protocols, and an understanding of the underlying fundamental principles behind these areas. The development of HT-specific PEMFC designs is of key importance that may help mitigate issues of membrane dehydration and MEA degradation.

  14. Compensated High Temperature Strain Gage

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A device for measuring strain in substrates at high temperatures in which the thermally induced apparent strain is nulled is described. Two gages are used, one active gage and one compensating gage. Both gages are placed on the substrate to be gaged; the active gage is attached such that it responds to mechanical and thermally induced apparent strain while the compensating gage is attached such that it does not respond to mechanical strain and and measures only thermally induced apparent strain. A thermal blanket is placed over the two gages to maintain the gages at the same temperature. The two gages are wired as adjacent arms of a wheatstone bridge which nulls the thermally induced apparent strain giving a true reading of the mechanical strain in the substrate.

  15. Ultra-High Temperature Ceramics

    NASA Technical Reports Server (NTRS)

    Rasky, Dan; Bull, Jeff

    1994-01-01

    Recent developments in ultra-high temperature ceramic composites, and their application to advanced vehicle thermal protection systems will be discussed. Research and testing of refractory ceramics has resulted in the identification of a new family of ceramic composites that promise temperature performance to 4000 F+, significantly beyond the current state-of-the-art of reusable systems which are limited to approximately 300 F. This new family of materials includes zirconium and hafnium diboride composites with various reinforcements, such as fibers and particulates. Preliminary material characterization and testing results, including plasma arc-jet testing of prototype vehicle components, will be described. Future directions for the research and material development activities will also be discussed.

  16. High Density And High Temperature Plasmas In Large Helical Device

    NASA Astrophysics Data System (ADS)

    Komori, A.

    2010-07-01

    For the realization of the fusion reactor, it is necessary to confine high density and high temperature plasma for a time, which is well known as the Lawson criterion. To improve the plasma or confinement performance, vigorous experiments have been performed in the Large Helical Device (LHD) in National Institute for Fusion Science, which is the largest superconducting heliotron device with R = 3.9 m r = 0.6 m, Bt = 3 T. Recently a promising confinement regime called Super Dense Core (SDC) mode was discovered. An extremely high density core region with more than ~ 1 × 10^20 m-3 is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB (? = 0.6) is very high and the particle confinement in the core region is ~ 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. The IDB-SDC mode is also favorable from the engineering point of view since one can moderate demands for heating devices and plasma facing components. In order to achieve the IDB-SDC mode, the central fuelling with the pellet injection and the low recycling condition are essential. A repetitive pellet injector was newly developed to continuously feed the particle source to the central region. For the recycling control, the effective divertor system should be employed to control the edge plasma. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature more than 10 keV with the formation of the internal transport barrier (ITB). In the core region, the heat conductivity is improved to the neoclassical level, while no clear ITB for electron was seen. Another interesting phenomenon called "impurity hole" was observed inside the ITB. During the high ion temperature discharge, the im- purity density in the core region becomes

  17. Temperature dependence of the liquid structure factor of dense monatomic fluids in the long wavelength limit in relation to thermal expansivity

    NASA Astrophysics Data System (ADS)

    March, N. H.; Alonso, J. A.

    2012-03-01

    The temperature dependence of the liquid structure factor S(k) of dense monatomic fluids, and especially a variety of liquid metals, is studied by combining thermodynamics and fluctuation theory in the long wavelength limit k → 0. Emphasis is placed on the connection of ? with thermal expansivity. Reference here is then made to recent semiempirical work of Lawson, who advocated an approximate relation, but at the melting temperature T m , between ? and the Gruneisen constant.

  18. High temperature sealed electrochemical cell

    SciTech Connect

    Valentin Chung, Brice Hoani; Burke, Paul J.; Sadoway, Donald R.

    2015-10-06

    A cell for high temperature electrochemical reactions is provided. The cell includes a container, at least a portion of the container acting as a first electrode. An extension tube has a first end and a second end, the extension tube coupled to the container at the second end forming a conduit from the container to said first end. A second electrode is positioned in the container and extends out of the container via the conduit. A seal is positioned proximate the first end of the extension tube, for sealing the cell.

  19. Passivation of high temperature superconductors

    NASA Technical Reports Server (NTRS)

    Vasquez, Richard P. (Inventor)

    1991-01-01

    The surface of high temperature superconductors such as YBa2Cu3O(7-x) are passivated by reacting the native Y, Ba and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that is impervious to water and has a solubility in water of no more than 10(exp -3) M. The passivating treatment is preferably conducted by immersing the surface in dilute aqueous acid solution since more soluble species dissolve into the solution. The treatment does not degrade the superconducting properties of the bulk material.

  20. High temperature insulation barrier composite

    NASA Technical Reports Server (NTRS)

    Onstott, Joseph W. (Inventor)

    1989-01-01

    A composite material suitable for providing insulation for the nozzle structure of the Space Shuttle and other similar surfaces is disclosed. The composite layer is comprised of an outer skin layer of nickel chromium and an interleaved inner region comprising a top layer of nickel chromium foil which acts as a primary convective shield. There are at least two layers of alumina batting adjacent to the layers of silicon carbide fabric. An additional layer of nickel chromium foil is used as a secondary convective shield. The composite is particularly advantageous for use as nozzle insulation because of its ability to withstand high reentry temperatures, its flexibility, oxidation resistance, low conductivity, and light weight.

  1. Advanced high-temperature batteries

    NASA Technical Reports Server (NTRS)

    Nelson, Paul A.

    1989-01-01

    The promise of very high specific energy and power was not yet achieved for practical battery systems. Some recent approaches are discussed for new approaches to achieving high performance for lithium/DeS2 cells and sodium/metal chloride cells. The main problems for the development of successful LiAl/FeS2 cells were the instability of the FeS2 electrode, which has resulted in rapidly declining capacity, the lack of an internal mechanism for accommodating overcharge of a cell, thus requiring the use of external charge control on each individual cell, and the lack of a suitable current collector for the positive electrode other than expensive molybdenum sheet material. Much progress was made in solving the first two problems. Reduction of the operating temperatures to 400 C by a change in electrolyte composition has increased the expected life to 1000 cycles. Also, a lithium shuttle mechanism was demonstrated for selected electrode compositions that permits sufficient overcharge tolerance to adjust for the normally expected cell-to-cell deviation in coulombic efficiency. Sodium/sulfur batteries and sodium/metal chloride batteries have demonstrated good reliability and long cycle life. For applications where very high power is desired, new electrolyte coinfigurations would be required. Design work was carried out for the sodium/metal chloride battery that demonstrates the feasibility of achieving high specific energy and high power for large battery cells having thin-walled high-surface area electrolytes.

  2. The effect of a fictitious peer on young children's choice of familiar v. unfamiliar low- and high-energy-dense foods.

    PubMed

    Bevelander, Kirsten E; Anschütz, Doeschka J; Engels, Rutger C M E

    2012-09-28

    The present experimental study was the first to investigate the impact of a remote (non-existent) peer on children's food choice of familiar v. unfamiliar low- and high-energy-dense food products. In a computer task, children (n 316; 50·3 % boys; mean age 7·13 (SD 0·75) years) were asked to choose between pictures of familiar and unfamiliar foods in four different choice blocks using the following pairs: (1) familiar v. unfamiliar low-energy-dense foods (fruits and vegetables), (2) familiar v. unfamiliar high-energy-dense foods (high sugar, salt and/or fat content), (3) familiar low-energy-dense v. unfamiliar high-energy-dense foods and (4) unfamiliar low-energy-dense v. familiar high-energy-dense foods. Participants who were not in the control group were exposed to the food choices (either always the familiar or always the unfamiliar food product) of a same-sex and same-age fictitious peer who was supposedly completing the same task at another school. The present study provided insights into children's choices between (un)familiar low- and high-energy-dense foods in an everyday situation. The findings revealed that the use of fictitious peers increased children's willingness to try unfamiliar foods, although children tended to choose high-energy-dense foods over low-energy-dense foods. Intervention programmes that use peer influence to focus on improving children's choice of healthy foods should take into account children's strong aversion to unfamiliar low-energy-dense foods as well as their general preference for familiar and unfamiliar high-energy-dense foods.

  3. Imaging monitored loosening of dense fibrous tissues using high-intensity pulsed ultrasound

    NASA Astrophysics Data System (ADS)

    Yeh, Chia-Lun; Li, Pai-Chi; Shih, Wen-Pin; Huang, Pei-Shin; Kuo, Po-Ling

    2013-10-01

    Pulsed high-intensity focused ultrasound (HIFU) is proposed as a new alternative treatment for contracture of dense fibrous tissue. It is hypothesized that the pulsed-HIFU can release the contracted tissues by attenuating tensile stiffness along the fiber axis, and that the stiffness reduction can be quantitatively monitored by change of B-mode images. Fresh porcine tendons and ligaments were adapted to an ex vivo model and insonated with pulsed-HIFU for durations ranging from 5 to 30 min. The pulse length was 91 µs with a repetition frequency of 500 Hz, and the peak rarefactional pressure was 6.36 MPa. The corresponding average intensities were kept around 1606 W cm-2 for ISPPA and 72.3 W cm-2 for ISPTA. B-mode images of the tissues were acquired before and after pulsed-HIFU exposure, and the changes in speckle intensity and organization were analyzed. The tensile stiffness of the HIFU-exposed tissues along the longitudinal axis was examined using a stretching machine. Histology examinations were performed by optical and transmission electron microscopy. Pulsed-HIFU exposure significantly decreased the tensile stiffness of the ligaments and tendons. The intensity and organization of tissue speckles in the exposed region were also decreased. The speckle changes correlated well with the degree of stiffness alteration. Histology examinations revealed that pulsed-HIFU exposure probably damages tissues via a cavitation-mediated mechanism. Our results suggest that pulsed-HIFU with a low duty factor is a promising tool for developing new treatment strategies for orthopedic disorders.

  4. High modulus high temperature glass fibers

    NASA Technical Reports Server (NTRS)

    Bacon, J. F.

    1973-01-01

    The search for a new high-modulus, high-temperature glass fiber involved the preparation of 500 glass compositions lying in 12 glass fields. These systems consisted primarily of low atomic number oxides and rare-earth oxides. Direct optical measurements of the kinetics of crystallization of the cordierite-rare earth system, for example, showed that the addition of rare-earth oxides decreased the rate of formation of cordierite crystals. Glass samples prepared from these systems proved that the rare-earth oxides made large specific contributions to the Young's modulus of the glasses. The best glasses have moduli greater than 21 million psi, the best glass fibers have moduli greater than 18 million psi, and the best glass fiber-epoxy resin composites have tensile strengths of 298,000 psi, compressive strengths of at least 220,000 psi, flexural strengths of 290,000 psi, and short-beam shear strengths of almost 17,000 psi.

  5. Multifunctional, High-Temperature Nanocomposites

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Smith, Joseph G.; Siochi, Emilie J.; Working, Dennis C.; Criss, Jim M.; Watson, Kent A.; Delozier, Donavon M.; Ghose, Sayata

    2007-01-01

    In experiments conducted as part of a continuing effort to incorporate multifunctionality into advanced composite materials, blends of multi-walled carbon nanotubes and a resin denoted gPETI-330 h (wherein gPETI h is an abbreviation for gphenylethynyl-terminated imide h) were prepared, characterized, and fabricated into moldings. PETI-330 was selected as the matrix resin in these experiments because of its low melt viscosity (<10 poise at a temperature of 280 C), excellent melt stability (lifetime >2 hours at 280 C), and high temperature performance (>1,000 hours at 288 C). The multi-walled carbon nanotubes (MWCNTs), obtained from the University of Kentucky, were selected because of their electrical and thermal conductivity and their small diameters. The purpose of these experiments was to determine the combination of thermal, electrical, and mechanical properties achievable while still maintaining melt processability. The PETI-330/MWCNT mixtures were prepared at concentrations ranging from 3 to 25 weight-percent of MWCNTs by dry mixing of the constituents in a ball mill using zirconia beads. The resulting powders were characterized for degree of mixing and thermal and rheological properties. The neat resin was found to have melt viscosity between 5 and 10 poise. At 280 C and a fixed strain rate, the viscosity was found to increase with time. At this temperature, the phenylethynyl groups do not readily react and so no significant curing of the resin occurred. For MWCNT-filled samples, melt viscosity was reasonably steady at 280 C and was greater in samples containing greater proportions of MWCNTs. The melt viscosity for 20 weightpercent of MWCNTs was found to be .28,000 poise, which is lower than the initial estimated allowable maximum value of 60,000 poise for injection molding. Hence, MWCNT loadings of as much as 20 percent were deemed to be suitable compositions for scale-up. High-resolution scanning electron microscopy (HRSEM) showed the MWCNTs to be well

  6. Sialons as high temperature insulators

    NASA Technical Reports Server (NTRS)

    Phillips, W. M.; Kuo, Y. S.

    1978-01-01

    Sialons were evaluated for application as high temperature electrical insulators in contact with molybdenum and tungsten components in hard vacuum applications. Both D.C. and variable frequency A.C. resistivity data indicate the sialons to have electrical resistivity similar to common oxide in the 1000 C or higher range. Metallographic evaluations indicate good bonding of the type 15R ALN polytype to molybdenum and tungsten. The beta prime or modified silicon nitride phase was unacceptable in terms of vacuum stability. Additives effect on electrical resistivity. Similar resistivity decreases were produced by additions of molybdenum or tungsten to form cermets. The use of hot pressing at 1800 C with ALN, Al2 O3 and Si3N4 starting powders produced a better product than did a combination of SiO2 and AIN staring powders. It was indicated that sialons will be suitable insulators in the 1600K range in contact with molybdenum or tungsten if they are produced as a pure ceramic and subsequently bonded to the metal components at temperatures in the 1600K range.

  7. Comparison of Local Scale Measured and Modeled Brightness Temperatures and Snow Parameters from the CLPX 2003 by Means of a Dense Medium Radiative Transfer Theory Model

    NASA Technical Reports Server (NTRS)

    Tedescol, Marco; Kim, Edward J.; Cline, Don; Graf, Tobias; Koike, Toshio; Armstrong, Richard; Brodzik, Mary J.; Hardy, Janet

    2004-01-01

    Microwave remote sensing offers distinct advantages for observing the cryosphere. Solar illumination is not required, and spatial and temporal coverage are excellent from polar-orbiting satellites. Passive microwave measurements are sensitive to the two most useful physical quantities for many hydrological applications: physical temperature and water content/state. Sensitivity to the latter is a direct result of the microwave sensitivity to the dielectric properties of natural media, including snow, ice, soil (frozen or thawed), and vegetation. These considerations are factors motivating the development of future cryospheric satellite remote sensing missions, continuing and improving on a 26-year microwave measurement legacy. Perhaps the biggest issues regarding the use of such satellite measurements involve how to relate parameter values at spatial scales as small as a hectare to observations with sensor footprints that may be up to 25 x 25 km. The NASA Cold-land Processes Field Experiment (CLPX) generated a dataset designed to enhance understanding of such scaling issues. CLPX observations were made in February (dry snow) and March (wet snow), 2003 in Colorado, USA, at scales ranging from plot scale to 25 x 25 km satellite footprints. Of interest here are passive microwave observations from ground-based, airborne, and satellite sensors, as well as meteorological and snowpack measurements that will enable studies of the effects of spatial heterogeneity of surface conditions on the observations. Prior to performing such scaling studies, an evaluation of snowpack forward modelling at the plot scale (least heterogeneous scale) is in order. This is the focus of this paper. Many forward models of snow signatures (brightness temperatures) have been developed over the years. It is now recognized that a dense medium radiative transfer (DMRT) treatment represents a high degree of physical fidelity for snow modeling, yet dense medium models are particularly sensitive to

  8. Single-source-precursor synthesis of dense SiC/HfC(x)N(1-x)-based ultrahigh-temperature ceramic nanocomposites.

    PubMed

    Wen, Qingbo; Xu, Yeping; Xu, Binbin; Fasel, Claudia; Guillon, Olivier; Buntkowsky, Gerd; Yu, Zhaoju; Riedel, Ralf; Ionescu, Emanuel

    2014-11-21

    A novel single-source precursor was synthesized by the reaction of an allyl hydrido polycarbosilane (SMP10) and tetrakis(dimethylamido)hafnium(iv) (TDMAH) for the purpose of preparing dense monolithic SiC/HfC(x)N(1-x)-based ultrahigh temperature ceramic nanocomposites. The materials obtained at different stages of the synthesis process were characterized via Fourier transform infrared (FT-IR) as well as nuclear magnetic resonance (NMR) spectroscopy. The polymer-to-ceramic transformation was investigated by means of MAS NMR and FT-IR spectroscopy as well as thermogravimetric analysis (TGA) coupled with in situ mass spectrometry. Moreover, the microstructural evolution of the synthesized SiHfCN-based ceramics annealed at different temperatures ranging from 1300 °C to 1800 °C was characterized by elemental analysis, X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM). Based on its high temperature behavior, the amorphous SiHfCN-based ceramic powder was used to prepare monolithic SiC/HfC(x)N(1-x)-based nanocomposites using the spark plasma sintering (SPS) technique. The results showed that dense monolithic SiC/HfC(x)N(1-x)-based nanocomposites with low open porosity (0.74 vol%) can be prepared successfully from single-source precursors. The average grain size of both HfC0.83N0.17 and SiC phases was found to be less than 100 nm after SPS processing owing to a unique microstructure: HfC0.83N0.17 grains were embedded homogeneously in a β-SiC matrix and encapsulated by in situ formed carbon layers which acted as a diffusion barrier to suppress grain growth. The segregated Hf-carbonitride grains significantly influenced the electrical conductivity of the SPS processed monolithic samples. While Hf-free polymer-derived SiC showed an electrical conductivity of ca. 1.8 S cm(-1), the electrical conductivity of the Hf-containing material was analyzed to be ca. 136.2 S cm(-1).

  9. Superior intrinsic thermoelectric performance with zT of 1.8 in single-crystal and melt-quenched highly dense Cu(2-x)Se bulks.

    PubMed

    Zhao, Lan-ling; Wang, Xiao-lin; Wang, Ji-yang; Cheng, Zhen-xiang; Dou, Shi-xue; Wang, Jun; Liu, Li-qiang

    2015-01-08

    Practical applications of the high temperature thermoelectric materials developed so far are partially obstructed by the costly and complicated fabrication process. In this work, we put forward two additional important properties for thermoelectric materials, high crystal symmetry and congruent melting. We propose that the recently discovered thermoelectric material Cu2-xSe, with figure of merit, zT, over 1.5 at T of ~ 1000 K, should meet these requirements, based on our analysis of its crystal structure and the Cu-Se binary phase diagram. We found that its excellent thermoelectric performance is intrinsic, and less dependent on grain size, while highly dense samples can be easily fabricated by a melt-quenching approach. Our results reveal that the melt-quenched samples and single crystals exhibit almost the same superior thermoelectric performance, with zT as high as 1.7-1.8 at T of ~973 K. Our findings not only provide a cheap and fast fabrication method for highly dense Cu(2-x)Se bulks with superior thermoelectric performance, paving the way for possible commercialization of Cu2-xSe as an outstanding component in practical thermoelectric modules, but also provide guidance in searching for new classes of thermoelectric systems with high crystal symmetry or further improving the cost performance of other existing congruent-melting thermoelectric materials.

  10. Faraday imaging at high temperatures

    DOEpatents

    Hackel, Lloyd A.; Reichert, Patrick

    1997-01-01

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid.

  11. Faraday imaging at high temperatures

    DOEpatents

    Hackel, L.A.; Reichert, P.

    1997-03-18

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid. 3 figs.

  12. High Temperature Particle Filtration Technology

    SciTech Connect

    Besmann, T.M.

    2001-11-13

    High temperature filtration can serve to improve the economic, environmental, and energy performance of chemical processes. This project was designed to evaluate the stability of filtration materials in the environments of the production of dimethyldichlorosilane (DDS). In cooperation with Dow Corning, chemical environments for the fluidized bed reactor where silicon is converted to DDS and the incinerator where vents are cornbusted were characterized. At Oak Ridge National Laboratory (ORNL) an exposure system was developed that could simulate these two environments. Filter samples obtained from third parties were exposed to the environments for periods up to 1000 hours. Mechanical properties before and after exposure were determined by burst-testing rings of filter material. The results indicated that several types of filter materials would likely perform well in the fluid bed environment, and two materials would be good candidates for the incinerator environment.

  13. High Temperature Capacitive Strain Gage

    NASA Technical Reports Server (NTRS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  14. High temperature control rod assembly

    DOEpatents

    Vollman, Russell E.

    1991-01-01

    A high temperature nuclear control rod assembly comprises a plurality of substantially cylindrical segments flexibly joined together in succession by ball joints. The segments are made of a high temperature graphite or carbon-carbon composite. The segment includes a hollow cylindrical sleeve which has an opening for receiving neutron-absorbing material in the form of pellets or compacted rings. The sleeve has a threaded sleeve bore and outer threaded surface. A cylindrical support post has a threaded shaft at one end which is threadably engaged with the sleeve bore to rigidly couple the support post to the sleeve. The other end of the post is formed with a ball portion. A hollow cylindrical collar has an inner threaded surface engageable with the outer threaded surface of the sleeve to rigidly couple the collar to the sleeve. the collar also has a socket portion which cooperates with the ball portion to flexibly connect segments together to form a ball and socket-type joint. In another embodiment, the segment comprises a support member which has a threaded shaft portion and a ball surface portion. The threaded shaft portion is engageable with an inner threaded surface of a ring for rigidly coupling the support member to the ring. The ring in turn has an outer surface at one end which is threadably engageably with a hollow cylindrical sleeve. The other end of the sleeve is formed with a socket portion for engagement with a ball portion of the support member. In yet another embodiment, a secondary rod is slidably inserted in a hollow channel through the center of the segment to provide additional strength. A method for controlling a nuclear reactor utilizing the control rod assembly is also included.

  15. Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling.

    PubMed

    Hashishin, Takeshi; Tan, Zhenquan; Yamamoto, Kazuhiro; Qiu, Nan; Kim, Jungeum; Numako, Chiya; Naka, Takashi; Valmalette, Jean Christophe; Ohara, Satoshi

    2014-04-25

    The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase.

  16. Quenching ilmenite with a high-temperature and high-pressure phase using super-high-energy ball milling

    NASA Astrophysics Data System (ADS)

    Hashishin, Takeshi; Tan, Zhenquan; Yamamoto, Kazuhiro; Qiu, Nan; Kim, Jungeum; Numako, Chiya; Naka, Takashi; Valmalette, Jean Christophe; Ohara, Satoshi

    2014-04-01

    The mass production of highly dense oxides with high-temperature and high-pressure phases allows us to discover functional properties that have never been developed. To date, the quenching of highly dense materials at the gramme-level at ambient atmosphere has never been achieved. Here, we provide evidence of the formation of orthorhombic Fe2TiO4 from trigonal FeTiO3 as a result of the high-temperature (>1250 K) and high-pressure (>23 GPa) condition induced by the high collision energy of 150 gravity generated between steel balls. Ilmenite was steeply quenched by the surrounding atmosphere, when iron-rich ilmenite (Fe2TiO4) with a high-temperature and high-pressure phase was formed by planetary collisions and was released from the collision points between the balls. Our finding allows us to infer that such intense planetary collisions induced by high-energy ball milling contribute to the mass production of a high-temperature and high-pressure phase.

  17. Large Area, High Resolution N2H+ studies of dense gas in the Perseus and Serpens Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Storm, Shaye; Mundy, Lee

    2014-07-01

    Star formation in molecular clouds occurs over a wide range of spatial scales and physical densities. Understanding the origin of dense cores thus requires linking the structure and kinematics of gas and dust from cloud to core scales. The CARMA Large Area Star Formation Survey (CLASSy) is a CARMA Key Project that spectrally imaged five diverse regions of the Perseus and Serpens Molecular Clouds in N2H+ (J=1-0), totaling over 800 square arcminutes. The observations have 7’’ angular resolution (~0.01 pc spatial resolution) to probe dense gas down to core scales, and use combined interferometric and single-dish data to fully recover line emission up to parsec scales. CLASSy observations are complete, and this talk will focus on three science results. First, the dense gas in regions with existing star formation has complex hierarchical structure. We present a non-binary dendrogram analysis for all regions and show that dense gas hierarchy correlates with star formation activity. Second, well-resolved velocity information for each dendrogram-identified structure allows a new way of looking at linewidth-size relations in clouds. Specifically, we find that non-thermal line-of-sight velocity dispersion varies weakly with structure size, while rms variation in the centroid velocity increases strongly with structure size. We argue that the typical line-of-sight depth of a cloud can be estimated from these relations, and that our regions have depths that are several times less than their extent on the plane of the sky. This finding is consistent with numerical simulations of molecular cloud turbulence that show that high-density sheets are a generic result. Third, N2H+ is a good tracer of cold, dense gas in filaments; we resolve multiple beams across many filaments, some of which are narrower than 0.1 pc. The centroid velocity fields of several filaments show gradients perpendicular to their major axis, which is a common feature in filaments formed from numerical

  18. Characterization of warm dense matter produced by laser-accelerated high-energy protons

    NASA Astrophysics Data System (ADS)

    Nakatsutsumi, M.; Fuchs, J.; Mancic, A.; Robiche, J.; Renaudin, P.; Combis, P.; Dorchies, F.; Harmand, M.; Maynard, G.; Vassaux, J.; Mora, P.; Antici, P.; Fourmaux, S.; Audebert, P.

    2008-11-01

    Producing warm dense plasmas (WDM: solid density, few eV ˜ few 10s eV) is of interest for fundamental plasma physics or ICF. Laser-produced proton heating is of interest since they are short (<1ps) and deposit their energy volumetrically. Experiments were performed using the LULI 100 TW facility to create and characterize WDM. We used, (i) 2D time-resolved optical self-emission of the heated target, (ii) surface expansion velocity measurement through phase measurements of a reflecting probe beam, and (iii) x-ray absorption spectroscopy. We showed that we could produce quasi-uniform heating of solids, as suited for e.g. EoS measurements. Time-resolved solid-liquid-plasma transition has been measured, as well as energy-loss of MeV protons in warm dense plasmas.

  19. High Pressure Study on High Temperature Superconductors

    NASA Astrophysics Data System (ADS)

    Lin, Jauyn Grace

    In spite of the progress on the understanding of high-temperature superconductivity (HTS), there is still not sufficient evidence to differentiate one theoretical model from the others. In an attempt to relate the crystal structures of high-temperature superconductors (HTS's) to the mechanism of HTS, we have adopted a chemico-physical approach by examining the pressure-effect on the superconducting and transport properties of superconducting compound systems. Without exception, all compounds exhibiting superconductivity above 77 K, the boiling point of liquid nitrogen, are anisotropic structures consisting of layers of CuO_2 , metal element (R's; where R is R being Ca, Y or rare-earth element) and metal-oxide (MO's; where M is Ca, Ba, Sr, Cu, Hg, Tl, Bi or Pb). We have investigated under pressure the electrical and superconducting properties of four highly related systems with different R's, different numbers of MO layers, different numbers of CuO _2 layers and various anion dopings. The specific systems studied were: RBa_2Cu _3O_7 (R = Y, Yb, Tm, Ho, Dy, Gd, Sm and Nd), R_{1 -x}Pr_{x}Ba _2Cu_3O _7 (R = Yb and Dy), Y_2Ba _4Cu_{5 + m} O_{13 + m} (m = 1, 2 and 3), and Tl_2Ba _2Ca_{L-1}Cu _{2L-1}O_ {4 + 2L-delta} (L= 1,2 and 3, and 0 <= delta <= 0.1). We found that: (1) in R-123, R affects T _{c} due to its chemical pressure which, in turn, can lead to a modification in the electronic structure of HTS's, in contrast to the general belief that R is isolated from the superconducting CuO_2 layers and hence has no influence on T _{c}; (2) the absence of superconductivity in PrBa_2Cu_3O _7 may be due to the low carrier concentration and hole-localization, in contrast to the suggestion of pair-breaking; (3) there may exist a common optimal T_{c} for all members of the homologous series Y_2Ba _4Cu_{5 + m} O_{13 + m}, raising the possibility of a similar situation in other compound families; and (4) We have observed a universal T _{c}-behavior for HTS's. We believe that these

  20. Dense arrays of highly aligned graphene nanoribbons produced by substrate-controlled metal-assisted etching of graphene.

    PubMed

    Solís-Fernández, Pablo; Yoshida, Kazuma; Ogawa, Yui; Tsuji, Masaharu; Ago, Hiroki

    2013-12-01

    Dense arrays of aligned graphene nanoribbons (GNRs) are fabricated by substrate-controlled etching of large-area single-layer graphene. An adequate choice of etching substrate and catalyst deposition method allows densities up to 25 nanoribbons μm(-1) to be obtained with average widths of 19 nm. The efficacy of the method is evidenced by the high on/off ratios of back-gated transistors made with these GNRs, which can go up to 5000. PMID:24030892

  1. High Temperature Solid Lubricant Coating for High Temperature Wear Applications

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher (Inventor); Edmonds, Brian J (Inventor)

    2014-01-01

    A self-lubricating, friction and wear reducing composite useful over a wide temperature range is described herein. The composite includes metal bonded chromium oxide dispersed in a metal binder having a substantial amount of nickel. The composite contains a fluoride of at least one Group I, Group II, or rare earth metal, and optionally a low temperature lubricant metal.

  2. Thermal disconnect for high-temperature batteries

    DOEpatents

    Jungst, Rudolph George; Armijo, James Rudolph; Frear, Darrel Richard

    2000-01-01

    A new type of high temperature thermal disconnect has been developed to protect electrical and mechanical equipment from damage caused by operation at extreme temperatures. These thermal disconnects allow continuous operation at temperatures ranging from 250.degree. C. to 450.degree. C., while rapidly terminating operation at temperatures 50.degree. C. to 150.degree. C. higher than the continuous operating temperature.

  3. Dense sampled transmission matrix for high resolution angular spectrum imaging through turbid media via compressed sensing (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jang, Hwanchol; Yoon, Changhyeong; Choi, Wonshik; Eom, Tae Joong; Lee, Heung-No

    2016-03-01

    We provide an approach to improve the quality of image reconstruction in wide-field imaging through turbid media (WITM). In WITM, a calibration stage which measures the transmission matrix (TM), the set of responses of turbid medium to a set of plane waves with different incident angles, is preceded to the image recovery. Then, the TM is used for estimation of object image in image recovery stage. In this work, we aim to estimate highly resolved angular spectrum and use it for high quality image reconstruction. To this end, we propose to perform a dense sampling for TM measurement in calibration stage with finer incident angle spacing. In conventional approaches, incident angle spacing is made to be large enough so that the columns in TM are out of memory effect of turbid media. Otherwise, the columns in TM are correlated and the inversion becomes difficult. We employ compressed sensing (CS) for a successful high resolution angular spectrum recovery with dense sampled TM. CS is a relatively new information acquisition and reconstruction framework and has shown to provide superb performance in ill-conditioned inverse problems. We observe that the image quality metrics such as contrast-to-noise ratio and mean squared error are improved and the perceptual image quality is improved with reduced speckle noise in the reconstructed image. This results shows that the WITM performance can be improved only by executing dense sampling in the calibration stage and with an efficient signal reconstruction framework without elaborating the overall optical imaging systems.

  4. High temperature alkali corrosion of dense SiC and Si{sub 3}N{sub 4} coated with CMZP and Mg-doped Al{sub 2}TiO{sub 5} in coal gas. Quarterly report, July 1, 1995--September 30, 1995

    SciTech Connect

    Yang, Shaokai; Brown, J.J.

    1995-10-02

    SiC samples coated with CMZP and Mg-Al{sub 2}TiO{sub 5}, respectively, were tested in a 100-hour slagging combustion test at the Energy and Environmental Research Center at the University of North Dakota. Results of measurements and analysis indicate that CMZP and Mg-Al{sub 2}TiO{sub 5} coatings improved the high temperature alkali corrosion resistance under coal combustion atmospheres. It is clearly shown that it is important to obtain a homogeneous and crack-free coating and good adhesion of the coating to the surface of the substrate for the best corrosion resistance. Some measures to improve the coating procedure are presented.

  5. Physical properties and formation of MCLD 126.6+24.5 : a dense cometary shape globule at high-Galactic latitude

    NASA Astrophysics Data System (ADS)

    Ristorcelli, Isabelle; Rivera-Ingraham, Alana; Juvela, Mika; Falgarone, Edith; Pelkonen, Veli-Matti; Pagani, Laurent; Ysard, Nathalie; Montier, Ludovic; Montillaud, Julien; Marshall, Douglas; Bernard, Jean-Philippe

    2015-08-01

    The high-latitude molecular clouds are mostly gravitationally unbound and an interesting question to be investigated is how dense cores can form in such tenuous, diffuse environment, and what is their ability to form stars. Are these dense cores forming from random fluctuations in a turbulent medium, or is their formation triggered by external mechanisms ?We present here a detailed analysis of the dense high-latitude clump MCLD 126.6+24.5 observed with PACS and SPIRE as part of the Herschel Key-Program ‘Galactic Cold Cores’, a follow-up of Planck detections. The clump lies in a tenuous high-latitude cloud, located at the border of the Polaris Flare, a large molecular cirrus cloud in the direction of the north celestial pole, at an estimated distance of 150 pc. Its cometary globule shape appears similar to what is usually found in globules in active star formation regions, although this nebula is far from any such region.The column density distribution derived from the Herschel data shows a very sharp edge and narrow transition between the diffuse medium and the molecular part of the cloud. This remarkable feature could be the signature of a shocked-compression flow from its southern side, likely associated with the North Celestial Pole HI loop. Cold cores are found embedded inside the globule, with temperatures down to 10K. We also analyse the properties of its 2 main filaments (including a pillar-like structure). We present their main characteristics, both in terms of dust and gas physical properties, combining the Herschel data with IRAM maps of 13CO and C18O. We compare the overall properties of the globule and its structure with predictions from MHD simulations in order to investigate the origin of this intriguing cometary shape globule found in high-galactic latitude diffuse environment.

  6. Preparation of dense bulk high T/sub c/ superconducting materials using hot isostatic pressing

    SciTech Connect

    Imam, M.A.; Sadananda, K.; Osofsky, M.

    1989-03-01

    It is important to improve the intergrain contact by eliminating internal porosity in sintered products. This is accomplished for Ba-Cu-O with Er or Nd, Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O systems using hot isostatic pressing (HIP). Sintered superconducting materials were encapsulated in an evacuated stainless steel or pyrex glass containers and processed in a HIP unit a high temperatures and pressures. Optimum HIP conditions to obtain bulk samples of nearly theoretical density were determined. Results indicate that in addition to density, HIP also improved T/sub c/. Furthermore, for the 1-2-3 system, the grain size is significantly reduced during HIP and is attributed to fracturing of course particles in the sintered compact due to high strain rates experienced during the pressurization. HIP materials can be machined to any shape and size and is being used for making specimens for J/sub c/ measurements and superconducting devices.

  7. High Temperature Polyimide Materials in Extreme Temperature Environments

    NASA Technical Reports Server (NTRS)

    Johnson, Theodore F.; Gates, Thomas S.

    2001-01-01

    At the end of the NASA High Speed Research (HSR) Program, NASA Langley Research Center (LaRC) began a program to screen the high-temperature Polymeric Composite Materials (PMCs) characterized by the HSR Durability Program for possible use in Reusable Launch Vehicles (RLVs) operating under extreme temperature conditions. The HSR Program focused on developing material-related technologies to enable a High Speed Civil Transport (HSCT) capable of operating temperatures ranging from 54 C (-65 F) to 177 C (350 F). A high-temperature polymeric resin, PETI-5 was used in the HSR Program to satisfy the requirements for performance and durability for a PMC. For RLVs, it was anticipated that this high temperature material would contribute to reducing the overall weight of a vehicle by eliminating or reducing the thermal protection required to protect the internal structural elements of the vehicle and increasing the structural strain limits. The tests were performed to determine temperature-dependent mechanical and physical proper-ties of IM7/PETI-5 composite over a temperature range from cryogenic temperature -253 C (-423F) to the material's maximum use temperature of 230 C (450 F). This paper presents results from the test program for the temperature-dependent mechanical and physical properties of IM7/PETI-5 composite in the temperature range from -253 C (-423 F) to 27 C (80 F).

  8. Single-source-precursor synthesis of dense SiC/HfCxN1-x-based ultrahigh-temperature ceramic nanocomposites

    NASA Astrophysics Data System (ADS)

    Wen, Qingbo; Xu, Yeping; Xu, Binbin; Fasel, Claudia; GuillonPresent Address: Forschungszentrum Jülich, Institut Für Energie-Und Klimaforschung 1: Werkstoffsynthese Und Herstellungsverfahren, Wilhelm-Johnen-Straße, D.-52425 Jülich., Olivier; Buntkowsky, Gerd; Yu, Zhaoju; Riedel, Ralf; Ionescu, Emanuel

    2014-10-01

    A novel single-source precursor was synthesized by the reaction of an allyl hydrido polycarbosilane (SMP10) and tetrakis(dimethylamido)hafnium(iv) (TDMAH) for the purpose of preparing dense monolithic SiC/HfCxN1-x-based ultrahigh temperature ceramic nanocomposites. The materials obtained at different stages of the synthesis process were characterized via Fourier transform infrared (FT-IR) as well as nuclear magnetic resonance (NMR) spectroscopy. The polymer-to-ceramic transformation was investigated by means of MAS NMR and FT-IR spectroscopy as well as thermogravimetric analysis (TGA) coupled with in situ mass spectrometry. Moreover, the microstructural evolution of the synthesized SiHfCN-based ceramics annealed at different temperatures ranging from 1300 °C to 1800 °C was characterized by elemental analysis, X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM). Based on its high temperature behavior, the amorphous SiHfCN-based ceramic powder was used to prepare monolithic SiC/HfCxN1-x-based nanocomposites using the spark plasma sintering (SPS) technique. The results showed that dense monolithic SiC/HfCxN1-x-based nanocomposites with low open porosity (0.74 vol%) can be prepared successfully from single-source precursors. The average grain size of both HfC0.83N0.17 and SiC phases was found to be less than 100 nm after SPS processing owing to a unique microstructure: HfC0.83N0.17 grains were embedded homogeneously in a β-SiC matrix and encapsulated by in situ formed carbon layers which acted as a diffusion barrier to suppress grain growth. The segregated Hf-carbonitride grains significantly influenced the electrical conductivity of the SPS processed monolithic samples. While Hf-free polymer-derived SiC showed an electrical conductivity of ca. 1.8 S cm-1, the electrical conductivity of the Hf-containing material was analyzed to be ca. 136.2 S cm-1.A novel single-source precursor was synthesized by the reaction of an allyl hydrido

  9. High-temperature thermocouples and related methods

    DOEpatents

    Rempe, Joy L.; Knudson, Darrell L.; Condie, Keith G.; Wilkins, S. Curt

    2011-01-18

    A high-temperature thermocouple and methods for fabricating a thermocouple capable of long-term operation in high-temperature, hostile environments without significant signal degradation or shortened thermocouple lifetime due to heat induced brittleness.

  10. High-temperature borehole instrumentation

    SciTech Connect

    Dennis, B.R.; Koczan, S.P.; Stephani, E.L.

    1985-10-01

    A new method of extracting natural heat from the earth's crust was invented at the Los Alamos National Laboratory in 1970. It uses fluid pressures (hydraulic fracturing) to produce cracks that connect two boreholes drilled into hot rock formations of low initial permeability. Pressurized water is then circulated through this connected underground loop to extract heat from the rock and bring it to the surface. The creation of the fracture reservior began with drilling boreholes deep within the Precambrian basement rock at the Fenton Hill Test Site. Hydraulic fracturing, flow testing, and well-completion operations required unique wellbore measurements using downhole instrumentation systems that would survive the very high borehole temperatures, 320/sup 0/C (610/sup 0/F). These instruments were not available in the oil and gas industrial complex, so the Los Alamos National Laboratory initiated an intense program upgrading existing technology where applicable, subcontracting materials and equipment development to industrial manufactures, and using the Laboratory resource to develop the necessary downhole instruments to meet programmatic schedules. 60 refs., 11 figs.

  11. High Temperature Superconducting Underground Cable

    SciTech Connect

    Farrell, Roger, A.

    2010-02-28

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the world’s first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  12. High-temperature borehole instrumentation

    NASA Astrophysics Data System (ADS)

    Dennis, B. R.; Koczan, S. P.; Stephani, E. L.

    1985-10-01

    A new method of extracting natural heat from the Earth's crust was invented at the Los Alamos National Laboratory in 1970. It uses fluid pressures (hydraulic fracturing) to produce cracks that connect two boreholes drilled into hot rock formations of low initial permeability. Pressurized water is then circulated through this connected underground loop to extract heat from the rock and bring it to the surface. The creation of the fracture reservior began with drilling boreholes deep within the Precambrian basement rock at the Fenton Hill Test Site. Hydraulic fracturing, flow testing, and well-completion operations required unique wellbore measurements using downhole instrumentation systems that would survive the very high borehole temperatures, 320(0)C (610(0)F). These instruments were not available in the oil and gas industrial complex, so the Los Alamos National Laboratory initiated an intense program upgrading existing technology where applicable, subcontracting materials and equipment development to industrial manufactures, and using the Laboratory resources to develop the necessary downhole instruments to meet programmatic schedules.

  13. High temperature suppression of dioxins.

    PubMed

    Zhan, Ming-Xiu; Chen, Tong; Fu, Jian-Ying; Lin, Xiao-Qing; Lu, Sheng-Yong; Li, Xiao-Dong; Yan, Jian-Hua; Buekens, Alfons

    2016-03-01

    Combined Sulphur-Nitrogen inhibitors, such as sewage sludge decomposition gases (SDG), thiourea and amidosulphonic acid have been observed to suppress the de novo synthesis of dioxins effectively. In this study, the inhibition of PCDD/Fs formation from model fly ash was investigated at unusually high temperatures (650 °C and 850 °C), well above the usual range of de novo tests (250-400 °C). At 650 °C it was found that SDG evolving from dried sewage sludge could suppress the formation of 2,3,7,8-substituted PCDD/Fs with high efficiency (90%), both in weight units and in I-TEQ units. Additionally, at 850 °C, three kinds of sulphur-amine or sulphur-ammonium compounds were tested to inhibit dioxins formation during laboratory-scale tests, simulating municipal solid waste incineration. The suppression efficiencies of PCDD/Fs formed through homogeneous gas phase reactions were all above 85% when 3 wt. % of thiourea (98.7%), aminosulphonic acid (96.0%) or ammonium thiosulphate (87.3%) was added. Differences in the ratio of PCDFs/PCDDs, in weight average chlorination level and in the congener distribution of the 17 toxic PCDD/Fs indicated that the three inhibitors tested followed distinct suppression pathways, possibly in relation to their different functional groups of nitrogen. Furthermore, thiourea reduced the (weight) average chlorinated level. In addition, the thermal decomposition of TUA was studied by means of thermogravimetry-fourier transform infrared spectroscopy (TG-FTIR) and the presence of SO2, SO3, NH3 and nitriles (N≡C bonds) was shown in the decomposition gases; these gaseous inhibitors might be the primary dioxins suppressants.

  14. A Low Collision and High Throughput Data Collection Mechanism for Large-Scale Super Dense Wireless Sensor Networks

    PubMed Central

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Gaura, Elena; Brusey, James; Zhang, Xuekun; Dutkiewicz, Eryk

    2016-01-01

    Super dense wireless sensor networks (WSNs) have become popular with the development of Internet of Things (IoT), Machine-to-Machine (M2M) communications and Vehicular-to-Vehicular (V2V) networks. While highly-dense wireless networks provide efficient and sustainable solutions to collect precise environmental information, a new channel access scheme is needed to solve the channel collision problem caused by the large number of competing nodes accessing the channel simultaneously. In this paper, we propose a space-time random access method based on a directional data transmission strategy, by which collisions in the wireless channel are significantly decreased and channel utility efficiency is greatly enhanced. Simulation results show that our proposed method can decrease the packet loss rate to less than 2% in large scale WSNs and in comparison with other channel access schemes for WSNs, the average network throughput can be doubled. PMID:27438839

  15. HIGH-PRESSURE PHYSICS. Direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium.

    PubMed

    Knudson, M D; Desjarlais, M P; Becker, A; Lemke, R W; Cochrane, K R; Savage, M E; Bliss, D E; Mattsson, T R; Redmer, R

    2015-06-26

    Eighty years ago, it was proposed that solid hydrogen would become metallic at sufficiently high density. Despite numerous investigations, this transition has not yet been experimentally observed. More recently, there has been much interest in the analog of this predicted metallic transition in the dense liquid, due to its relevance to planetary science. Here, we show direct observation of an abrupt insulator-to-metal transition in dense liquid deuterium. Experimental determination of the location of this transition provides a much-needed benchmark for theory and may constrain the region of hydrogen-helium immiscibility and the boundary-layer pressure in standard models of the internal structure of gas-giant planets.

  16. A Low Collision and High Throughput Data Collection Mechanism for Large-Scale Super Dense Wireless Sensor Networks.

    PubMed

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Gaura, Elena; Brusey, James; Zhang, Xuekun; Dutkiewicz, Eryk

    2016-07-18

    Super dense wireless sensor networks (WSNs) have become popular with the development of Internet of Things (IoT), Machine-to-Machine (M2M) communications and Vehicular-to-Vehicular (V2V) networks. While highly-dense wireless networks provide efficient and sustainable solutions to collect precise environmental information, a new channel access scheme is needed to solve the channel collision problem caused by the large number of competing nodes accessing the channel simultaneously. In this paper, we propose a space-time random access method based on a directional data transmission strategy, by which collisions in the wireless channel are significantly decreased and channel utility efficiency is greatly enhanced. Simulation results show that our proposed method can decrease the packet loss rate to less than 2 % in large scale WSNs and in comparison with other channel access schemes for WSNs, the average network throughput can be doubled.

  17. A Low Collision and High Throughput Data Collection Mechanism for Large-Scale Super Dense Wireless Sensor Networks.

    PubMed

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Gaura, Elena; Brusey, James; Zhang, Xuekun; Dutkiewicz, Eryk

    2016-01-01

    Super dense wireless sensor networks (WSNs) have become popular with the development of Internet of Things (IoT), Machine-to-Machine (M2M) communications and Vehicular-to-Vehicular (V2V) networks. While highly-dense wireless networks provide efficient and sustainable solutions to collect precise environmental information, a new channel access scheme is needed to solve the channel collision problem caused by the large number of competing nodes accessing the channel simultaneously. In this paper, we propose a space-time random access method based on a directional data transmission strategy, by which collisions in the wireless channel are significantly decreased and channel utility efficiency is greatly enhanced. Simulation results show that our proposed method can decrease the packet loss rate to less than 2 % in large scale WSNs and in comparison with other channel access schemes for WSNs, the average network throughput can be doubled. PMID:27438839

  18. Highly sensitive detection of copper ions by densely grafting fluorescein inside polyethyleneimine core-silica shell nanoparticles.

    PubMed

    Qiao, Yali; Zheng, Xingwang

    2015-12-21

    In this work, polyethyleneimine (PEI) core-silica shell nanoparticles were synthesized and used for densely grafting fluorescent receptor units inside the core of these particles to result in multi-receptor units collectively sensing a target. Herein, copper ion quenching of the fluorescence intensity of a fluorescein isothiocyanate (FITC) system was selected as a model to confirm our proof-of-concept strategy. Our results showed that, compared to free FITC in solution, a 10-fold enhancement of the Stern-Volmer constant value for Cu(2+) quenching of the fluorescence intensity of the grafted state of FITC in PEI core-silica shell nanoparticles was achieved. Furthermore, compared to a previous collective sensing scheme by densely grafting fluorescent receptor units on a silica nanoparticle surface, the proposed scheme, which grafted fluorescent receptor units inside a polymer nano-core, was simple, highly efficient and presented higher sensitivity.

  19. High-speed ultrasound imaging in dense suspensions reveals impact-activated solidification due to dynamic shear jamming

    NASA Astrophysics Data System (ADS)

    Han, Endao; Peters, Ivo R.; Jaeger, Heinrich M.

    2016-07-01

    A remarkable property of dense suspensions is that they can transform from liquid-like at rest to solid-like under sudden impact. Previous work showed that this impact-induced solidification involves rapidly moving jamming fronts; however, details of this process have remained unresolved. Here we use high-speed ultrasound imaging to probe non-invasively how the interior of a dense suspension responds to impact. Measuring the speed of sound we demonstrate that the solidification proceeds without a detectable increase in packing fraction, and imaging the evolving flow field we find that the shear intensity is maximized right at the jamming front. Taken together, this provides direct experimental evidence for jamming by shear, rather than densification, as driving the transformation to solid-like behaviour. On the basis of these findings we propose a new model to explain the anisotropy in the propagation speed of the fronts and delineate the onset conditions for dynamic shear jamming in suspensions.

  20. High temperature power electronics for space

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.; Overton, Eric

    1991-01-01

    A high temperature electronics program at NASA Lewis Research Center focuses on dielectric and insulating materials research, development and testing of high temperature power components, and integration of the developed components and devices into a demonstrable 200 C power system, such as inverter. An overview of the program and a description of the in-house high temperature facilities along with experimental data obtained on high temperature materials are presented.

  1. A high-powered siren for stable acoustic levitation of dense materials in the earth's gravity

    NASA Technical Reports Server (NTRS)

    Gammel, Paul M.; Croonquist, Arvid P.; Wang, Taylor G.

    1988-01-01

    Levitation of large dense samples (e.g., 1-cm diameter steel balls) has been performed in a 1-g environment. A siren was used to study the effects of reflector geometry and variable-frequency operation in order to attain stable acoustic positioning. The harmonic content and spatial distribution of the acoustic field have been investigated. The best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper reflector while operating at a frequency slightly below resonance.

  2. High Temperature Chemistry at NASA: Hot Topics

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.

    2014-01-01

    High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.

  3. A Fast Pulse, High Intensity Neutron Source Based Upon The Dense Plasma Focus

    SciTech Connect

    Krishnan, M.; Bures, B.; Madden, R.; Blobner, F.; Elliott, K. Wilson

    2009-12-02

    Alameda Applied Sciences Corporation (AASC) has built a bench-top source of fast neutrons (approx10-30 ns, 2.45 MeV), that is portable and can be scaled to operate at approx100 Hz. The source is a Dense Plasma Focus driven by three different capacitor banks: a 40 J/30 kA/100 Hz driver; a 500 J/130 kA/2 Hz driver and a 3 kJ/350 kA/0.5 Hz driver. At currents of approx130 kA, this source produces approx1x10{sup 7} (DD) n/pulse. The neutron pulse widths are approx10-30 ns and may be controlled by adjusting the DPF electrode geometry and operating parameters. This paper describes the scaling of the fast neutron output with current from such a Dense Plasma Focus source. For each current and driver, different DPF head designs are required to match to the current rise-time, as the operating pressure and anode radius/shape are varied. Doping of the pure D{sub 2} gas fill with Ar or Kr was shown earlier to increase the neutron output. Results are discussed in the light of scaling laws suggested by prior literature.

  4. High-Sensitivity Temperature Measurement

    ERIC Educational Resources Information Center

    Leadstone, G. S.

    1978-01-01

    Describes a method of measuring small temperature differences that amount to a .01K, using an arrangement of a copper-constantan thermocouple, a microamplifier and a galvanometer, as an indirect way of measuring heat energy. (GA)

  5. Measurement of thermodynamic temperature of high temperature fixed points

    SciTech Connect

    Gavrilov, V. R.; Khlevnoy, B. B.; Otryaskin, D. A.; Grigorieva, I. A.; Samoylov, M. L.; Sapritsky, V. I.

    2013-09-11

    The paper is devoted to VNIIOFI's measurements of thermodynamic temperature of the high temperature fixed points Co-C, Pt-C and Re-C within the scope of the international project coordinated by the Consultative Committee for Thermometry working group 5 'Radiation Thermometry'. The melting temperatures of the fixed points were measured by a radiance mode radiation thermometer calibrated against a filter radiometer with known irradiance spectral responsivity via a high temperature black body. This paper describes the facility used for the measurements, the results and estimated uncertainties.

  6. High Temperature Filler for Tile Gaps

    NASA Technical Reports Server (NTRS)

    Holt, J. W.; Wang, D. S.

    1983-01-01

    Gaps between ceramic tiles filled with ceramic-coated fabric that withstands temperatures as high as 2,000 degrees F (1,300 degrees C). Reusable high-temperature gap filler is made of fabric coated with ceramic slurry and bonded in place with room-temperature-vulcanized adhesive. Procedure used in kilns and furnaces.

  7. High temperature superconducting fault current limiter

    DOEpatents

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  8. High temperature superconducting fault current limiter

    DOEpatents

    Hull, J.R.

    1997-02-04

    A fault current limiter for an electrical circuit is disclosed. The fault current limiter includes a high temperature superconductor in the electrical circuit. The high temperature superconductor is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter. 15 figs.

  9. High temperature ceramic interface study

    NASA Technical Reports Server (NTRS)

    Lindberg, L. J.

    1984-01-01

    Monolithic SiC and Si3N4 are susceptible to contact stress damage at static and sliding interfaces. Transformation-toughened zirconia (TTZ) was evaluated under sliding contact conditions to determine if the higher material fracture toughness would reduce the susceptibility to contact stress damage. Contact stress tests were conducted on four commercially available TTZ materials at normal loads ranging from 0.455 to 22.7 kg (1 to 50 pounds) at temperatures ranging from room temperature to 1204C (2200 F). Static and dynamic friction were measured as a function of temperature. Flexural strength measurements after these tests determined that the contact stress exposure did not reduce the strength of TTZ at contact loads of 0.455, 4.55, and 11.3 kg (1, 10, and 25 pounds). Prior testing with the lower toughness SiC and Si3N4 materials resulted in a substantial strength reduction at loads of only 4.55 and 11.3 kg (10 and 25 pounds). An increase in material toughness appears to improve ceramic material resistance to contact stress damage. Baseline material flexure strength was established and the stress rupture capability of TTZ was evaluated. Stress rupture tests determined that TTZ materials are susceptible to deformation due to creep and that aging of TTZ materials at elevated temperatures results in a reduction of material strength.

  10. Deep Trek High Temperature Electronics Project

    SciTech Connect

    Bruce Ohme

    2007-07-31

    This report summarizes technical progress achieved during the cooperative research agreement between Honeywell and U.S. Department of Energy to develop high-temperature electronics. Objects of this development included Silicon-on-Insulator (SOI) wafer process development for high temperature, supporting design tools and libraries, and high temperature integrated circuit component development including FPGA, EEPROM, high-resolution A-to-D converter, and a precision amplifier.

  11. Low-temperature ({<=}200 Degree-Sign C) plasma enhanced atomic layer deposition of dense titanium nitride thin films

    SciTech Connect

    Samal, Nigamananda; Du Hui; Luberoff, Russell; Chetry, Krishna; Bubber, Randhir; Hayes, Alan; Devasahayam, Adrian

    2013-01-15

    Titanium nitride (TiN) has been widely used in the semiconductor industry for its diffusion barrier and seed layer properties. However, it has seen limited adoption in other industries in which low temperature (<200 Degree-Sign C) deposition is a requirement. Examples of applications which require low temperature deposition are seed layers for magnetic materials in the data storage (DS) industry and seed and diffusion barrier layers for through-silicon-vias (TSV) in the MEMS industry. This paper describes a low temperature TiN process with appropriate electrical, chemical, and structural properties based on plasma enhanced atomic layer deposition method that is suitable for the DS and MEMS industries. It uses tetrakis-(dimethylamino)-titanium as an organometallic precursor and hydrogen (H{sub 2}) as co-reactant. This process was developed in a Veeco NEXUS Trade-Mark-Sign chemical vapor deposition tool. The tool uses a substrate rf-biased configuration with a grounded gas shower head. In this paper, the complimentary and self-limiting character of this process is demonstrated. The effects of key processing parameters including temperature, pulse time, and plasma power are investigated in terms of growth rate, stress, crystal morphology, chemical, electrical, and optical properties. Stoichiometric thin films with growth rates of 0.4-0.5 A/cycle were achieved. Low electrical resistivity (<300 {mu}{Omega} cm), high mass density (>4 g/cm{sup 3}), low stress (<250 MPa), and >85% step coverage for aspect ratio of 10:1 were realized. Wet chemical etch data show robust chemical stability of the film. The properties of the film have been optimized to satisfy industrial viability as a Ruthenium (Ru) preseed liner in potential data storage and TSV applications.

  12. High temperature tensile testing of ceramic composites

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Hemann, John H.

    1988-01-01

    The various components of a high temperature tensile testing system are evaluated. The objective is the high temperature tensile testing of SiC fiber reinforced reaction bonded Si3N4 specimens at test temperatures up to 1650 C (3000 F). Testing is to be conducted in inert gases and air. Gripping fixtures, specimen configurations, furnaces, optical strain measuring systems, and temperature measurement techniques are reviewed. Advantages and disadvantages of the various techniques are also noted.

  13. Nature of the Schottky-type barrier of highly dense SnO2 systems displaying nonohmic behavior

    NASA Astrophysics Data System (ADS)

    Bueno, P. R.; de Cassia-Santos, M. R.; Leite, E. R.; Longo, E.; Bisquert, J.; Garcia-Belmonte, G.; Fabregat-Santiago, F.

    2000-12-01

    The electrical characteristics of highly dense SnO2 ceramic varistors are believed to be caused by the existence of potential barriers at the grain boundary. A complex plane analysis technique (to eliminate the influence of trapping activity associated with the conductance term observed via depression angle of a semicircular relaxation in the complex capacitance plane), allied with an approached Mott-Schottky model, are used to demonstrate that the potential barriers at the grain boundary are Schottky-type barriers in SnO2 varistors such as those observed in the traditional ZnO varistor.

  14. Dynamic, High-Temperature, Flexible Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M.; Sirocky, Paul J.

    1989-01-01

    New seal consists of multiple plies of braided ceramic sleeves filled with small ceramic balls. Innermost braided sleeve supported by high-temperature-wire-mesh sleeve that provides both springback and preload capabilities. Ceramic balls reduce effect of relatively high porosity of braided ceramic sleeves by acting as labyrinth flow path for gases and thereby greatly increasing pressure gradient seal can sustain. Dynamic, high-temperature, flexible seal employed in hypersonic engines, two-dimensional convergent/divergent and vectorized-thrust exhaust nozzles, reentry vehicle airframes, rocket-motor casings, high-temperature furnaces, and any application requiring non-asbestos high-temperature gaskets.

  15. Application of the UMACS process to highly dense U1-xAmxO2±δ MABB fuel fabrication for the DIAMINO irradiation

    NASA Astrophysics Data System (ADS)

    Delahaye, Thibaud; Lebreton, Florent; Horlait, Denis; Herlet, Nathalie; Dehaudt, Philippe

    2013-01-01

    The DIAMINO irradiation program aims to assess the influence of Am content and microstructure on He release and fuel swelling for different irradiation temperatures during heterogeneous transmutation in the OSIRIS reactor. Such irradiation programs call for ceramic fuels compliant with strict specifications. In the case of the DIAMINO experiment, Am-bearing blanket fuels with two compositions (U1-xAmxO2±δ (x = 0.075, 0.15)) and two microstructures (dense and porous) were selected, corresponding with four sample sets. Porous samples (<85%TD) were fabricated using a process previously developed for a similar irradiation program while a new dedicated process, UMACS, was developed and applied to produce dense samples. Despite americium presence, this process, based on conventional sintering, produces samples with high density (˜96%TD) close to that usually obtained for UO2. In the case of Minor Actinide Bearing Blankets (MABB), such a result has never been obtained reproducibly even with reactive sintering or impregnation methods.

  16. CO/H2, C/CO, OH/CO, and OH/O2 in dense interstellar gas: from high ionization to low metallicity

    NASA Astrophysics Data System (ADS)

    Bialy, Shmuel; Sternberg, Amiel

    2015-07-01

    We present numerical computations and analytic scaling relations for interstellar ion-molecule gas-phase chemistry down to very low metallicities (10-3 × solar), and/or up to high driving ionization rates. Relevant environments include the cool interstellar medium (ISM) in low-metallicity dwarf galaxies, early enriched clouds at the reionization and Pop-II star formation era, and in dense cold gas exposed to intense X-ray or cosmic ray sources. We focus on the behaviour for H2, CO, CH, OH, H2O and O2, at gas temperatures ˜100 K, characteristic of a cooled ISM at low metallicities. We consider shielded or partially shielded one-zone gas parcels, and solve the gas-phase chemical rate equations for the steady-state `metal-molecule abundances for a wide range of ionization parameters, ζ/n, and metallicties, Z '. We find that the OH abundances are always maximal near the H-to-H2 conversion points, and that large OH abundances persist at very low metallicities even when the hydrogen is predominantly atomic. We study the OH/O2, C/CO and OH/CO abundance ratios, from large to small, as functions of ζ/n and Z '. Much of the cold dense ISM for the Pop-II generation may have been OH-dominated and atomic rather than CO-dominated and molecular.

  17. High temperature silicon carbide impregnated insulating fabrics

    NASA Technical Reports Server (NTRS)

    Schomburg, C.; Dotts, R. L. (Inventor)

    1982-01-01

    High temperature insulating articles having improved performance characteristics are described. The articles comprise fabrics of closely woven refractory or heat resistant fibers having particles of silicon carbide dispersed at least partially through the fabric and bonded to the fibers with an emulsifiable polyethylene wax. Such articles exhibit significantly increased high temperature emittance characteristics and an improved retention of integrity and flexibility after prolonged exposure to high temperature.

  18. Experiments and Simulations on Magnetically Driven Implosions in High Repetition Rate Dense Plasma Focus

    NASA Astrophysics Data System (ADS)

    Caballero Bendixsen, Luis; Bott-Suzuki, Simon; Cordaro, Samuel; Krishnan, Mahadevan; Chapman, Stephen; Coleman, Phil; Chittenden, Jeremy

    2015-11-01

    Results will be shown on coordinated experiments and MHD simulations on magnetically driven implosions, with an emphasis on current diffusion and heat transport. Experiments are run at a Mather-type dense plasma focus (DPF-3, Vc: 20 kV, Ip: 480 kA, E: 5.8 kJ). Typical experiments are run at 300 kA and 0.33 Hz repetition rate with different gas loads (Ar, Ne, and He) at pressures of ~ 1-3 Torr, usually gathering 1000 shots per day. Simulations are run at a 96-core HP blade server cluster using 3GHz processors with 4GB RAM per node.Preliminary results show axial and radial phase plasma sheath velocity of ~ 1x105 m/s. These are in agreement with the snow-plough model of DPFs. Peak magnetic field of ~ 1 Tesla in the radial compression phase are measured. Electron densities on the order of 1018 cm-3 anticipated. Comparison between 2D and 3D models with empirical results show a good agreement in the axial and radial phase.

  19. Experimental Determination of DT Yield in High Current DD Dense Plasma Focii

    SciTech Connect

    Lowe, D. R.; Hagen, E. C.; Meehan, B. T.; Springs, R. K.; O'Brien, R. J.

    2013-06-18

    Dense Plasma Focii (DPF), which utilize deuterium gas to produce 2.45 MeV neutrons, may in fact also produce DT fusion neutrons at 14.1 MeV due to the triton production in the DD reaction. If beam-target fusion is the primary producer of fusion neutrons in DPFs, it is possible that ejected tritons from the first pinch will interact with the second pinch, and so forth. The 2 MJ DPF at National Security Technologies’ Losee Road Facility is able to, and has produced, over 1E12 DD neutrons per pulse, allowing an accurate measurement of the DT/DD ratio. The DT/DD ratio was experimentally verified by using the (n,2n) reaction in a large piece of praseodymium metal, which has a threshold reaction of 8 MeV, and is widely used as a DT yield measurement system1. The DT/DD ratio was experimentally determined for over 100 shots, and then compared to independent variables such as tube pressure, number of pinches per shot, total current, pinch current and charge voltage.

  20. High Resolution Remote Sensing of Densely Urbanised Regions: a Case Study of Hong Kong

    PubMed Central

    Nichol, Janet E.; Wong, Man Sing

    2009-01-01

    Data on the urban environment such as climate or air quality is usually collected at a few point monitoring stations distributed over a city. However, the synoptic viewpoint of satellites where a whole city is visible on a single image permits the collection of spatially comprehensive data at city-wide scale. In spite of rapid developments in remote sensing systems, deficiencies in image resolution and algorithm development still exist for applications such as air quality monitoring and urban heat island analysis. This paper describes state-of-the-art techniques for enhancing and maximising the spatial detail available from satellite images, and demonstrates their applications to the densely urbanised environment of Hong Kong. An Emissivity Modulation technique for spatial enhancement of thermal satellite images permits modelling of urban microclimate in combination with other urban structural parameters at local scale. For air quality monitoring, a Minimum Reflectance Technique (MRT) has been developed for MODIS 500 m images. The techniques described can promote the routine utilization of remotely sensed images for environmental monitoring in cities of the 21st century. PMID:22408549

  1. Dense High e +/e- Ratio Pair Creation using the Texas Petawatt Laser

    NASA Astrophysics Data System (ADS)

    Liang, Edison; Henderson, Alexander; Fu, Wen; Clarke, Taylor; Taylor, Devin; Lo, Willie; Chaguine, Petr; Hasson, Hannah; Dyer, Gillis; Serratto, Kristina; Riley, Nathan; Donovan, Michael; Ditmire, Todd

    2015-11-01

    We report results of pair creation experiments using ~ 100 Joule pulses of the Texas Petawatt Laser to irradiate solid gold and platinum targets, with intensities up to 1.9x1021W.cm-2 and pulse durations as short as 130 fs. Positron to electron (e +/e-) ratios exceeding 15% were observed for many thick disks (>=4mm) and long narrow rod targets, with the highest observed e +/e- ratio approaching 50% for a Pt rod. The inferred pair yield was few x10 10 with emerging pair density reaching 1015/cc so that the pair skin depth becomes <dense pair-dominated plasma with e +/e- approaching 100% and pair skin depth <

  2. Advanced high-temperature batteries

    NASA Technical Reports Server (NTRS)

    Nelson, P. A.

    1989-01-01

    Recent results for Li-Al/FeS2 cells and bipolar battery design have shown the possibility of achieving high specific energy (210 Wh/kg) and high specific power (239 W/kg) at the cell level for an electric vehicle application. Outstanding performance is also projected for sodium/metal chloride cells having large electrolyte areas and thin positive electrodes.

  3. Electric field-induced magnetization switching in interface-coupled multiferroic heterostructures: a highly-dense, non-volatile, and ultra-low-energy computing paradigm

    NASA Astrophysics Data System (ADS)

    Roy, Kuntal

    2014-06-01

    Electric field-induced magnetization switching in multiferroic magnetoelectric devices is promising for computing purposes in beyond Moore's law era. We show here that interface-coupled multiferroic heterostructures, i.e., a ferroelectric layer coupled with a ferromagnetic layer, are particularly suitable for highly-dense, non-volatile, and ultra-low-energy computing. By solving the stochastic Landau-Lifshitz-Gilbert equation of magnetization dynamics in the presence of room-temperature thermal fluctuations, we demonstrate that error-resilient switching of magnetization is possible with a sub-nanosecond delay while expending only a minuscule amount of energy, of ˜1 attojoule. Such devices can be operated by drawing energy from the environment without the need for an external battery.

  4. Investigations into High Temperature Components and Packaging

    SciTech Connect

    Marlino, L.D.; Seiber, L.E.; Scudiere, M.B.; M.S. Chinthavali, M.S.; McCluskey, F.P.

    2007-12-31

    The purpose of this report is to document the work that was performed at the Oak Ridge National Laboratory (ORNL) in support of the development of high temperature power electronics and components with monies remaining from the Semikron High Temperature Inverter Project managed by the National Energy Technology Laboratory (NETL). High temperature electronic components are needed to allow inverters to operate in more extreme operating conditions as required in advanced traction drive applications. The trend to try to eliminate secondary cooling loops and utilize the internal combustion (IC) cooling system, which operates with approximately 105 C water/ethylene glycol coolant at the output of the radiator, is necessary to further reduce vehicle costs and weight. The activity documented in this report includes development and testing of high temperature components, activities in support of high temperature testing, an assessment of several component packaging methods, and how elevated operating temperatures would impact their reliability. This report is organized with testing of new high temperature capacitors in Section 2 and testing of new 150 C junction temperature trench insulated gate bipolar transistor (IGBTs) in Section 3. Section 4 addresses some operational OPAL-GT information, which was necessary for developing module level tests. Section 5 summarizes calibration of equipment needed for the high temperature testing. Section 6 details some additional work that was funded on silicon carbide (SiC) device testing for high temperature use, and Section 7 is the complete text of a report funded from this effort summarizing packaging methods and their reliability issues for use in high temperature power electronics. Components were tested to evaluate the performance characteristics of the component at different operating temperatures. The temperature of the component is determined by the ambient temperature (i.e., temperature surrounding the device) plus the

  5. Development of high temperature strain gages

    NASA Technical Reports Server (NTRS)

    Lemcoe, M. M.

    1973-01-01

    High temperature electric resistance wire strain gages were developed and evaluated for use at temperatures exceeding 922 K (1200 F). A special high temperature strain gage alloy (Fe-25Cr-7.5A1), designated BCL-3, was used to fabricate the gages. Pertinent gage characteristics were determined at temperatures up to 1255 K (1800 F). The results of the evaluation were reported in graphical and tabular form. It was concluded that the gages will perform satisfactorily at temperatures to at least 1089 K (1500 F) for at least one hour.

  6. Nuclear fuels for very high temperature applications

    SciTech Connect

    Lundberg, L.B.; Hobbins, R.R.

    1992-01-01

    The success of the development of nuclear thermal propulsion devices and thermionic space nuclear power generation systems depends on the successful utilization of nuclear fuel materials at temperatures in the range 2000 to 3500 K. Problems associated with the utilization of uranium bearing fuel materials at these very high temperatures while maintaining them in the solid state for the required operating times are addressed. The critical issues addressed include evaporation, melting, reactor neutron spectrum, high temperature chemical stability, fabrication, fission induced swelling, fission product release, high temperature creep, thermal shock resistance, and fuel density, both mass and fissile atom. Candidate fuel materials for this temperature range are based on UO{sub 2} or uranium carbides. Evaporation suppression, such as a sealed cladding, is required for either fuel base. Nuclear performance data needed for design are sparse for all candidate fuel forms in this temperature range, especially at the higher temperatures.

  7. Nuclear fuels for very high temperature applications

    SciTech Connect

    Lundberg, L.B.; Hobbins, R.R.

    1992-08-01

    The success of the development of nuclear thermal propulsion devices and thermionic space nuclear power generation systems depends on the successful utilization of nuclear fuel materials at temperatures in the range 2000 to 3500 K. Problems associated with the utilization of uranium bearing fuel materials at these very high temperatures while maintaining them in the solid state for the required operating times are addressed. The critical issues addressed include evaporation, melting, reactor neutron spectrum, high temperature chemical stability, fabrication, fission induced swelling, fission product release, high temperature creep, thermal shock resistance, and fuel density, both mass and fissile atom. Candidate fuel materials for this temperature range are based on UO{sub 2} or uranium carbides. Evaporation suppression, such as a sealed cladding, is required for either fuel base. Nuclear performance data needed for design are sparse for all candidate fuel forms in this temperature range, especially at the higher temperatures.

  8. A stable and high resolution optical waveguide biosensor based on dense TiO2/Ag multilayer film

    NASA Astrophysics Data System (ADS)

    Jin, Zhao; Guan, Weiming; Liu, Chang; Xue, Tianyu; Wang, Qiyu; Zheng, Weitao; Cui, Xiaoqiang

    2016-07-01

    Optical waveguide (OWG) biosensor has attracted much attention according to the high sensitivity and resolution compared with conventional surface plasmon resonance (SPR) biosensor. Nanoporous materials are usually used as the waveguide layer for absorbing analytes into the porous structure and enhancing the sensor signal. However, this kind of waveguide layer provides poor protection to the metal film and leads to the damage of the biosensor. Ag film can provide great sensitivity in SPR sensing comparing to other metal but was rarely used because of its poor chemical stability. Fabricating high stability Ag based SPR biosensor is still a challenge. In this work we produce an OWG biosensor using a dense TiO2 film as the waveguide layer which provides high resolution and remarkable protection to the metal film. This waveguide structure makes long time detection possible using Ag as the metal layer and is able to lead an enhancement of sensitivity comparing to the Au-based biosensor.

  9. Nutrient-dense food groups have high energy costs: an econometric approach to nutrient profiling.

    PubMed

    Maillot, Matthieu; Darmon, Nicole; Darmon, Michel; Lafay, Lionel; Drewnowski, Adam

    2007-07-01

    Consumers wishing to replace some of the foods in their diets with more nutrient-dense options need to be able to identify such foods on the basis of nutrient profiling. The present study used nutrient profiling to rank 7 major food groups and 25 subgroups in terms of their contribution to dietary energy, diet quality, and diet cost for 1332 adult participants in the French National INCA1 Study. Nutrient profiles were based on the presence of 23 qualifying nutrients, expressed as the percentage of nutrient adequacy per 8 MJ, and 3 negative or disqualifying nutrients, expressed as the percentage of the maximal recommended values for saturated fatty acids, added sugar, and sodium per 1.4 kg. Calculated cost of energy (euro/8 MJ) was based on the mean retail price of 619 foods in the nutrient composition database. The meat and the fruit and vegetables food groups had the highest nutritional quality but were associated with highest energy costs. Sweets and salted snacks had the lowest nutritional quality but were also one of the least expensive sources of dietary energy. Starches and grains were unique because they were low in disqualifying nutrients yet provided low-cost dietary energy. Within each major food group, some subgroups had a higher nutritient-to-price ratio than others. However, the fact that food groups with the more favorable nutrient profiles were also associated with higher energy costs suggests that the present structure of food prices may be a barrier to the adoption of food-based dietary guidelines, at least by low-income households.

  10. Corrosion Resistant Coatings for High Temperature Applications

    SciTech Connect

    Besman, T.M.; Cooley, K.M.; Haynes, J.A.; Lee, W.Y.; Vaubert, V.M.

    1998-12-01

    Efforts to increase efficiency of energy conversion devices have required their operation at ever higher temperatures. This will force the substitution of higher-temperature structural ceramics for lower temperature materials, largely metals. Yet, many of these ceramics will require protection from high temperature corrosion caused by combustion gases, atmospheric contaminants, or the operating medium. This paper discusses examples of the initial development of such coatings and materials for potential application in combustion, aluminum smelting, and other harsh environments.

  11. Spin Hall magnetoresistance at high temperatures

    SciTech Connect

    Uchida, Ken-ichi; Qiu, Zhiyong; Kikkawa, Takashi; Iguchi, Ryo; Saitoh, Eiji

    2015-02-02

    The temperature dependence of spin Hall magnetoresistance (SMR) in Pt/Y{sub 3}Fe{sub 5}O{sub 12} (YIG) bilayer films has been investigated in a high temperature range from room temperature to near the Curie temperature of YIG. The experimental results show that the magnitude of the magnetoresistance ratio induced by the SMR monotonically decreases with increasing the temperature and almost disappears near the Curie temperature. We found that, near the Curie temperature, the temperature dependence of the SMR in the Pt/YIG film is steeper than that of a magnetization curve of the YIG; the critical exponent of the magnetoresistance ratio is estimated to be 0.9. This critical behavior of the SMR is attributed mainly to the temperature dependence of the spin-mixing conductance at the Pt/YIG interface.

  12. Borehole Stability in High-Temperature Formations

    NASA Astrophysics Data System (ADS)

    Yan, Chuanliang; Deng, Jingen; Yu, Baohua; Li, Wenliang; Chen, Zijian; Hu, Lianbo; Li, Yang

    2014-11-01

    In oil and gas drilling or geothermal well drilling, the temperature difference between the drilling fluid and formation will lead to an apparent temperature change around the borehole, which will influence the stress state around the borehole and tend to cause borehole instability in high geothermal gradient formations. The thermal effect is usually not considered as a factor in most of the conventional borehole stability models. In this research, in order to solve the borehole instability in high-temperature formations, a calculation model of the temperature field around the borehole during drilling is established. The effects of drilling fluid circulation, drilling fluid density, and mud displacement on the temperature field are analyzed. Besides these effects, the effect of temperature change on the stress around the borehole is analyzed based on thermoelasticity theory. In addition, the relationships between temperature and strength of four types of rocks are respectively established based on experimental results, and thermal expansion coefficients are also tested. On this basis, a borehole stability model is established considering thermal effects and the effect of temperature change on borehole stability is also analyzed. The results show that the fracture pressure and collapse pressure will both increase as the temperature of borehole rises, and vice versa. The fracture pressure is more sensitive to temperature. Temperature has different effects on collapse pressures due to different lithological characters; however, the variation of fracture pressure is unrelated to lithology. The research results can provide a reference for the design of drilling fluid density in high-temperature wells.

  13. Recrystallization of high temperature superconductors

    SciTech Connect

    Kouzoudis, D.

    1996-05-09

    Currently one of the most widely used high {Tc} superconductors is the Bi-based compounds Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub z} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub z} (known as BSCCO 2212 and 2223 compounds) with {Tc} values of about 85 K and 110 K respectively. Lengths of high performance conductors ranging from 100 to 1000 m long are routinely fabricated and some test magnets have been wound. An additional difficulty here is that although Bi-2212 and Bi-2223 phases exist over a wide range of stoichiometries, neither has been prepared in phase-pure form. So far the most successful method of constructing reliable and robust wires or tapes is the so called powder-in-tube (PIT) technique [1, 2, 3, 4, 5, 6, 7] in which oxide powder of the appropriate stoichiometry and phase content is placed inside a metal tube, deformed into the desired geometry (round wire or flat tape), and annealed to produce the desired superconducting properties. Intermediate anneals are often incorporated between successive deformation steps. Silver is the metal used in this process because it is the most compatible with the reacting phase. In all of the commercial processes for BSCCO, Ag seems to play a special catalytic role promoting the growth of high performance aligned grains that grow in the first few micrometers near the Ag/BSCCO interface. Adjacent to the Ag, the grain alignment is more perfect and the current density is higher than in the center of the tape. It is known that Ag lowers the melting point of several of the phases but the detailed mechanism for growth of these high performance grains is not clearly understood. The purpose of this work is to study the nucleation and growth of the high performance material at this interface.

  14. High temperature resistant cermet and ceramic compositions

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (Inventor)

    1978-01-01

    Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

  15. Copper Alloy For High-Temperature Uses

    NASA Technical Reports Server (NTRS)

    Dreshfield, Robert L.; Ellis, David L.; Michal, Gary

    1994-01-01

    Alloy of Cu/8Cr/4Nb (numbers indicate parts by atom percent) improved over older high-temperature copper-based alloys in that it offers enhanced high temperature strength, resistance to creep, and ductility while retaining most of thermal conductivity of pure copper; in addition, alloy does not become embrittled upon exposure to hydrogen at temperatures as high as 705 degrees C. Designed for use in presence of high heat fluxes and active cooling; for example, in heat exchangers in advanced aircraft and spacecraft engines, and other high-temperature applications in which there is need for such material. High conductivity and hardness of alloy exploited in welding electrodes and in high-voltage and high-current switches and other applications in which wear poses design problem.

  16. Silicon carbide, a high temperature semiconductor

    NASA Technical Reports Server (NTRS)

    Powell, J. A.

    1983-01-01

    Electronic applications are described that would benefit from the availability of high temperature semiconductor devices. Comparisons are made among potential materials for these devices and the problems of each are discussed. Recent progress in developing silicon carbide as a high temperature semiconductor is described.

  17. Evaluation of high temperature polymers

    NASA Technical Reports Server (NTRS)

    Jayaraj, K.; Dorogy, W.; Farrell, B.; Landrau, N.

    1995-01-01

    The purpose of this paper is to identify and develop arc-track resistant insulation materials that can operate reliably at 300 C. In the first phase, high performance polymers are evaluated based on structure, thermal stability and electrical properties. Next, the polymers are ranked according to performance and experimental characterization. Then, experimental evaluations in wire configuration are conducted. And selection is made based on performance and commerical potential.

  18. High temperature superconductors for computer interconnect applications

    SciTech Connect

    Nilsson, B.J.L.

    1994-12-31

    High temperature superconductors, because of their extremely low loss at high frequencies and their high current handling capability, have the potential for use in computer interconnect boards. They offer the potential advantages of high interconnect density, reduced interconnect delays, and higher data rate. Because silicon CMOS circuits dramatically improve in performance at low temperatures, cooled computers may become attractive in the future to capture both the improved interconnect and circuit benefits.

  19. High-temperature Solar Cell Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Merritt, Danielle; Raffaelle, Ryne P.; Scheiman, David

    2005-01-01

    The vast majority of space probes to date have relied upon photovoltaic power generation. If future missions designed to probe environments close to the sun (Figure 1) will be able to use such power generation, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. The significant problem is that solar cells lose performance at high temperatures.

  20. High temperature solar selective coatings

    DOEpatents

    Kennedy, Cheryl E

    2014-11-25

    Improved solar collectors (40) comprising glass tubing (42) attached to bellows (44) by airtight seals (56) enclose solar absorber tubes (50) inside an annular evacuated space (54. The exterior surfaces of the solar absorber tubes (50) are coated with improved solar selective coatings {48} which provide higher absorbance, lower emittance and resistance to atmospheric oxidation at elevated temperatures. The coatings are multilayered structures comprising solar absorbent layers (26) applied to the meta surface of the absorber tubes (50), typically stainless steel, topped with antireflective Savers (28) comprising at least two layers 30, 32) of refractory metal or metalloid oxides (such as titania and silica) with substantially differing indices of refraction in adjacent layers. Optionally, at least one layer of a noble metal such as platinum can be included between some of the layers. The absorbent layers cars include cermet materials comprising particles of metal compounds is a matrix, which can contain oxides of refractory metals or metalloids such as silicon. Reflective layers within the coating layers can comprise refractory metal silicides and related compounds characterized by the formulas TiSi. Ti.sub.3SiC.sub.2, TiAlSi, TiAN and similar compounds for Zr and Hf. The titania can be characterized by the formulas TiO.sub.2, Ti.sub.3O.sub.5. TiOx or TiO.sub.xN.sub.1-x with x 0 to 1. The silica can be at least one of SiO.sub.2, SiO.sub.2x or SiO.sub.2xN.sub.1-x with x=0 to 1.

  1. High-speed ultrasound imaging in dense suspensions reveals impact-activated solidification due to dynamic shear jamming

    PubMed Central

    Han, Endao; Peters, Ivo R.; Jaeger, Heinrich M.

    2016-01-01

    A remarkable property of dense suspensions is that they can transform from liquid-like at rest to solid-like under sudden impact. Previous work showed that this impact-induced solidification involves rapidly moving jamming fronts; however, details of this process have remained unresolved. Here we use high-speed ultrasound imaging to probe non-invasively how the interior of a dense suspension responds to impact. Measuring the speed of sound we demonstrate that the solidification proceeds without a detectable increase in packing fraction, and imaging the evolving flow field we find that the shear intensity is maximized right at the jamming front. Taken together, this provides direct experimental evidence for jamming by shear, rather than densification, as driving the transformation to solid-like behaviour. On the basis of these findings we propose a new model to explain the anisotropy in the propagation speed of the fronts and delineate the onset conditions for dynamic shear jamming in suspensions. PMID:27436628

  2. High-speed ultrasound imaging in dense suspensions reveals impact-activated solidification due to dynamic shear jamming.

    PubMed

    Han, Endao; Peters, Ivo R; Jaeger, Heinrich M

    2016-01-01

    A remarkable property of dense suspensions is that they can transform from liquid-like at rest to solid-like under sudden impact. Previous work showed that this impact-induced solidification involves rapidly moving jamming fronts; however, details of this process have remained unresolved. Here we use high-speed ultrasound imaging to probe non-invasively how the interior of a dense suspension responds to impact. Measuring the speed of sound we demonstrate that the solidification proceeds without a detectable increase in packing fraction, and imaging the evolving flow field we find that the shear intensity is maximized right at the jamming front. Taken together, this provides direct experimental evidence for jamming by shear, rather than densification, as driving the transformation to solid-like behaviour. On the basis of these findings we propose a new model to explain the anisotropy in the propagation speed of the fronts and delineate the onset conditions for dynamic shear jamming in suspensions. PMID:27436628

  3. Coherent Raman scattering in high-pressure/high-temperature fluids: An overview

    SciTech Connect

    Schmidt, S.C.; Moore, D.S.

    1990-01-01

    The present understanding of high-pressure/high-temperature dense-fluid behavior is derived almost exclusively from hydrodynamic and thermodynamic measurements. Such results average over the microscopic aspects of the materials and are, therefore, insufficient for a complete understanding of fluid behavior. At the present, dense-fluid models can be verified only to the extend that they agree with the macroscopic measurements. Recently, using stimulated Raman scattering, Raman induced Kerr effect scattering, and coherent anti-Stokes Raman scattering, we have been able to probe some of the microscopic phenomenology of these dense fluids. In this paper, we discuss primarily the use of CARS in conjunction with a two-stage light-gas gun to obtain vibrational spectra of shock-compressed liquid N{sub 2}, O{sub 2}, CO, their mixtures, CH{sub 3}NO{sub 2}, and N{sub 2}O. These experimental spectra are compared to synthetic spectra calculated using a semiclassical model for CARS intensities and best fit vibrational frequencies, peak Raman susceptibilities, and Raman linewidths. For O{sub 2}, the possibility of resonance enhancement from collision-induced absorption is addressed. Shifts in the vibrational frequencies reflect the influence of increased density and temperature on the intramolecular motion. The derived parameters suggest thermal equilibrium of the vibrational levels is established less than a few nanoseconds after shock passage. Vibrational temperatures are obtained that agree with those derived from equation-of-state calculations. Measured linewidths suggest that vibrational dephasing times have decreased to subpicosecond values at the highest shock pressures.

  4. Structural characterization of high temperature composites

    NASA Technical Reports Server (NTRS)

    Mandell, J. F.; Grande, D. H.

    1991-01-01

    Glass, ceramic, and carbon matrix composite materials have emerged in recent years with potential properties and temperature resistance which make them attractive for high temperature applications such as gas turbine engines. At the outset of this study, only flexural tests were available to evaluate brittle matrix composites at temperatures in the 600 to 1000 C range. The results are described of an ongoing effort to develop appropriate tensile, compression, and shear test methods for high temperature use. A tensile test for unidirectional composites was developed and used to evaluate the properties and behavior of ceramic fiber reinforced glass and glass-ceramic matrix composites in air at temperatures up to 1000 C. The results indicate generally efficient fiber reinforcement and tolerance to matrix cracking similar to polymer matrix composites. Limiting properties in these materials may be an inherently very low transverse strain to failure, and high temperature embrittlement due to fiber/matrix interface oxidation.

  5. Probing X-ray irradiation in the nucleus of NGC 1068 with observations of high-J lines of dense gas tracers

    NASA Astrophysics Data System (ADS)

    Pérez-Beaupuits, J. P.; Spaans, M.; van der Tak, F. F. S.; Aalto, S.; García-Burillo, S.; Fuente, A.; Usero, A.

    2009-08-01

    Context: Single-dish observations of molecular tracers have suggested that both star formation and an AGN can drive the gas chemistry of the central ~kpc of active galaxies. The irradiation by UV photons from an starburst or by X-rays from an AGN is expected to produce different signatures in molecular chemistry, which existing data on low-J lines cannot distinguish, as they do not trace gas at high temperature and density. Depending on the angular scale of a galaxy, the observed low-J lines can be dominated by the emission coming from the starburst ring rather than from the central region. Aims: With the incorporation of high-J molecular lines, we aim to constrain the physical conditions of the dense gas in the central region of the Seyfert 2 galaxy NGC 1068 and to determine signatures of the AGN or the starburst contribution. Methods: We used the James Clerk Maxwell Telescope to observe the J = 4-3 transition of HCN, HNC, and HCO^+, as well as the CN NJ = 25/2-13/2 and NJ = 35/2-25/2, in NGC 1068. We estimate the excitation conditions of HCN, HNC, and CN, based on the line intensity ratios and radiative transfer models. We discuss the results in the context of models of irradiation of the molecular gas by UV light and X-rays. Results: A first-order estimate leads to starburst contribution factors of 0.58 and 0.56 for the CN and HCN J=1-0 lines, respectively. We find that the bulk emission of HCN, HNC, CN, and the high-J HCO+ emerge from dense gas (n(H2) ≥ 105 cm-3). However, the low-J HCO+ lines (dominating the HCO+ column density) trace less dense (n(H2) < 105 cm-3) and colder (TK ≤ 20 K) gas, whereas the high-J HCO+ emerges from warmer (> 30 K) gas than the other molecules. We also find that the HNC/HCN and CN/HCN line intensity ratios decrease with increasing rotational quantum number J. Conclusions: The HCO+ J = 4-3 line intensity, compared with the lower transition lines and with the HCN J = 4-3 line, support the influence of a local XDR environment. The

  6. Super-dense array of Ge quantum dots grown on Si(100) by low-temperature molecular beam epitaxy

    SciTech Connect

    Talochkin, A. B. Shklyaev, A. A.; Mashanov, V. I.

    2014-04-14

    Ge layer grown on Si(100) at the low temperature of ∼100 °C by molecular beam epitaxy is studied using scanning tunneling microscopy and Raman spectroscopy. It is found that crystalline and pseudomorphic to the Si substrate Ge islands are formed at the initial growth stage. The islands acquire the base size of 1.2–2.6 nm and they form arrays with the super-high density of (5–8) × 10{sup 12} cm{sup −2} at 1–2 nm Ge coverages. Such a density is at least 10 times higher than that of Ge “hut” clusters grown via the Stranski-Krastanov growth mode. It is shown that areas between the crystalline Ge islands are filled with amorphous Ge, which is suggested to create potential barrier for holes localized within the islands. As a result, crystalline Ge quantum dots appear being isolated from each other.

  7. Effect of temperature on the shape of spatial quasi-periodic oscillations of the refractive index of alkali atoms in an optically dense medium with a closed excitation contour of Δ type

    SciTech Connect

    Barantsev, K A; Litvinov, A N

    2014-10-31

    A theory of a closed excitation contour (Δ system) of a three-level atom in an optically dense medium is constructed with allowance for temperature. The spatial quasi-periodic oscillations of the refractive index in the system under study are shown to damp with increasing temperature. The range of temperatures at which these oscillations are most pronounced is found. (quantum optics)

  8. A batteryless temperature sensor based on high temperature sensitive material

    NASA Astrophysics Data System (ADS)

    Bakkali, Asma; Pelegri-Sebastia, José; Laghmich, Youssef; Lyhyaoui, Abdelouahid

    2016-05-01

    The major challenge in wireless sensor networks is the reduction of energy consumption. Passive wireless sensor network is an attractive solution for measuring physical parameters in harsh environment for large range of applications requiring sensing devices with low cost of fabrication, small size and long term measurement stability. Batteryless temperature sensing techniques are an active research field. The approach developed in our work holds a promising future for temperature sensor applications in order to successfully reduce the energy consumption. The temperature sensor presented in this paper is based on the electromagnetic transduction principle using the integration of the high temperature sensitive material into a passive structure. Variation in temperature makes the dielectric constant of this material changing, and such modification induces variation in the resonant frequencies of high-Q whispering-gallery modes (WGM) in the millimeter-wave frequency range. Following the results achieved, the proposed device shows a linear response to the increasing temperature and these variations can be remotely detected from a radar interrogation. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  9. Sandia_HighTemperatureComponentEvaluation_2015.

    SciTech Connect

    Cashion, Avery T.

    2015-03-01

    The objective of this project is to perform independent evaluation of high temperature components to determine their suitability for use in high temperature geothermal tools. Development of high temperature components has been increasing rapidly due to demand from the high temperature oil and gas exploration and aerospace industries. Many of these new components are at the late prototype or first production stage of development and could benefit from third party evaluation of functionality and lifetime at elevated temperatures. In addition to independent testing of new components, this project recognizes that there is a paucity of commercial-off-the-shelf COTS components rated for geothermal temperatures. As such, high-temperature circuit designers often must dedicate considerable time and resources to determine if a component exists that they may be able to knead performance out of to meet their requirements. This project aids tool developers by characterization of select COTS component performances beyond published temperature specifications. The process for selecting components includes public announcements of project intent (e.g., FedBizOps), direct discussions with candidate manufacturers,and coordination with other DOE funded programs.

  10. Low to high temperature energy conversion system

    NASA Technical Reports Server (NTRS)

    Miller, C. G. (Inventor)

    1977-01-01

    A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

  11. Wafer scale fabrication of highly dense and uniform array of sub-5 nm nanogaps for surface enhanced Raman scatting substrates.

    PubMed

    Cai, Hongbing; Wu, YuKun; Dai, Yanmeng; Pan, Nan; Tian, Yangchao; Luo, Yi; Wang, Xiaoping

    2016-09-01

    Metallic nanogap is very important for a verity of applications in plasmonics. Although several fabrication techniques have been proposed in the last decades, it is still a challenge to produce uniform nanogaps with a few nanometers gap distance and high throughput. Here we present a simple, yet robust method based on the atomic layer deposition (ALD) and lift-off technique for patterning ultranarrow nanogaps array. The ability to accurately control the thickness of the ALD spacer layer enables us to precisely define the gap size, down to sub-5 nm scale. Moreover, this new method allows to fabricate uniform nanogaps array along different directions densely arranged on the wafer-scale substrate. It is demonstrated that the fabricated array can be used as an excellent substrate for surface enhanced Raman scatting (SERS) measurements of molecules, even on flexible substrates. This uniform nanogaps array would also find its applications for the trace detection and biosensors. PMID:27607684

  12. Dense Hypervelocity Plasma Jets

    NASA Astrophysics Data System (ADS)

    Case, Andrew; Witherspoon, F. Douglas; Messer, Sarah; Bomgardner, Richard; Phillips, Michael; van Doren, David; Elton, Raymond; Uzun-Kaymak, Ilker

    2007-11-01

    We are developing high velocity dense plasma jets for fusion and HEDP applications. Traditional coaxial plasma accelerators suffer from the blow-by instability which limits the mass accelerated to high velocity. In the current design blow-by is delayed by a combination of electrode shaping and use of a tailored plasma armature created by injection of a high density plasma at a few eV generated by arrays of capillary discharges or sparkgaps. Experimental data will be presented for a complete 32 injector gun system built for driving rotation in the Maryland MCX experiment, including data on penetration of the plasma jet through a magnetic field. We present spectroscopic measurements of plasma velocity, temperature, and density, as well as total momentum measured using a ballistic pendulum. Measurements are in agreement with each other and with time of flight data from photodiodes and a multichannel PMT. Plasma density is above 10^15 cm-3, velocities range up to about 100 km/s. Preliminary results from a quadrature heterodyne HeNe interferometer are consistent with these results.

  13. Silicon Carbide Nanotube Oxidation at High Temperatures

    NASA Technical Reports Server (NTRS)

    Ahlborg, Nadia; Zhu, Dongming

    2012-01-01

    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

  14. Aeronautical applications of high-temperature superconductors

    NASA Technical Reports Server (NTRS)

    Turney, George E.; Luidens, Roger W.; Uherka, Kenneth; Hull, John

    1989-01-01

    The successful development of high-temperature superconductors (HTS) could have a major impact on future aeronautical propulsion and aeronautical flight vehicle systems. A preliminary examination of the potential application of HTS for aeronautics indicates that significant benefits may be realized through the development and implementation of these newly discovered materials. Applications of high-temperature superconductors (currently substantiated at 95 K) were envisioned for several classes of aeronautical systems, including subsonic and supersonic transports, hypersonic aircraft, V/STOL aircraft, rotorcraft, and solar, microwave and laser powered aircraft. Introduced and described are the particular applications and potential benefits of high-temperature superconductors as related to aeronautics and/or aeronautical systems.

  15. Symposium on high temperature and materials chemistry

    SciTech Connect

    Not Available

    1989-10-01

    This volume contains the written proceedings of the Symposium on High Temperature and Materials Chemistry held in Berkeley, California on October 24--25, 1989. The Symposium was sponsored by the Materials and Chemical Sciences Division of Lawrence Berkeley Laboratory and by the College of Chemistry of the University of California at Berkeley to discuss directions, trends, and accomplishments in the field of high temperature and materials chemistry. Its purpose was to provide a snapshot of high temperature and materials chemistry and, in so doing, to define status and directions.

  16. The high temperature superconductivity space experiment

    NASA Technical Reports Server (NTRS)

    Webb, Denis C.; Nisenoff, M.

    1991-01-01

    The history and the current status of the high temperature superconductivity space experiment (HTSSE) initiated in 1988 are briefly reviewed. The goal of the HTSSE program is to demonstrate the feasibility of incorporating high temperature superconductivity (HTS) technology into space systems. The anticipated payoffs include the development of high temperature superconductor devices for space systems; preparation and space qualification of a cryogenically cooled experimental package containing HTS devices and components; and acquisition of data for future space experiments using more complex HTS devices and subsystems. The principal HTSSE systems and devices are described.

  17. Dimensionality of high temperature superconductivity in oxides

    NASA Technical Reports Server (NTRS)

    Chu, C. W.

    1989-01-01

    Many models have been proposed to account for the high temperature superconductivity observed in oxide systems. Almost all of these models proposed are based on the uncoupled low dimensional carrier Cu-O layers of the oxides. Results of several experiments are presented and discussed. They suggest that the high temperature superconductivity observed cannot be strictly two- or one-dimensional, and that the environment between the Cu-O layers and the interlayer coupling play an important role in the occurrence of such high temperature superconductivity. A comment on the very short coherence length reported is also made.

  18. A high-temperature wideband pressure transducer

    NASA Technical Reports Server (NTRS)

    Zuckerwar, A. J.

    1975-01-01

    Progress in the development of a pressure transducer for measurement of the pressure fluctuations in the high temperature environment of a jet exhaust is reported. A condenser microphone carrier system was adapted to meet the specifications. A theoretical analysis is presented which describes the operation of the condenser microphone in terms of geometry, materials, and other physical properties. The analysis was used as the basis for design of a prototype high temperature microphone. The feasibility of connecting the microphone to a converter over a high temperature cable operating as a half-wavelength transmission line was also examined.

  19. High temperature solid state storage cell

    DOEpatents

    Rea, Jesse R.; Kallianidis, Milton; Kelsey, G. Stephen

    1983-01-01

    A completely solid state high temperature storage cell comprised of a solid rechargeable cathode such as TiS.sub.2, a solid electrolyte which remains solid at the high temperature operating conditions of the cell and which exhibits high ionic conductivity at such elevated temperatures such as an electrolyte comprised of lithium iodide, and a solid lithium or other alkali metal alloy anode (such as a lithium-silicon alloy) with 5-50% by weight of said anode being comprised of said solid electrolyte.

  20. High Temperature Thermographic Phosphor Coatings Development

    NASA Technical Reports Server (NTRS)

    Goedeke, Shawn; Allison, S. W.; Beshears, D. L.; Bencic, T.; Cates, M. R.; Hollerman, W. A.; Guidry, R.

    2003-01-01

    For many years, phosphor thermometry has been used for non-contact temperature measurements. A large number of applications have been associated with high temperatures, especially for aerospace systems where blackbody radiation backgrounds are large and in challenging environments, such as vibration, rotation, flame, or noise. These environments restrict the use of more common thermocouples or infrared thermometric techniques. In particular, temperature measurements inside jet turbines, rocket engines, or similar devices are especially amenable to phosphor techniques. Often the fluorescent materials are used as powders, either suspended in binders and applied like paint or applied as high-temperature sprays. Thin coatings that are less than 50 m thick are used on the surfaces of interest. These coatings will quickly assume the same temperature as the surface to which they are applied. The temperature dependence of fluorescent materials is a function of the base matrix atoms and a small quantity of added activator or dopant ions. Often for high temperature applications, the selected materials are refractory and include rare earth ions. Phosphors like Y3Al5O12 (YAG) doped with Eu, Dy, or Tm, Y2O3 doped with Eu, or similar rare earth compounds, will survive high temperatures and can be configured to emit light that changes rapidly in lifetime and intensity. For example, researchers at Oak Ridge National Laboratory recently observed fluorescence from YAG:Dy and YAG:Tm at temperatures above 1400 C. One of the biggest challenges is to locate a binder material that can withstand tremendous variations in temperature in an adverse aerospace environment. This poster will provide an overview into our attempt to utilize phosphors for thermometry purposes. Emphasis will be placed on the use of selected binder materials that can withstand high temperatures. This research was completed for the National Aeronautics and Space Administration's Glenn Research Center in Cleveland

  1. High temperature acclimation through PIF4 signaling.

    PubMed

    Proveniers, Marcel C G; van Zanten, Martijn

    2013-02-01

    Ambient temperature has direct consequences for plant functioning. Many plant species are able to adjust reproductive timing and development to optimize fitness to changes in ambient temperatures. Understanding the molecular networks of how plants cope with high temperatures is essential to counteract the effects of global warming and to secure future crop productivity. Several recent papers reported that Arabidopsis thaliana responses to changing light conditions and high temperature, and their underlying signaling mechanisms are highly similar and involve the basic helix-loop-helix (bHLH) transcription factor PHYTOCHROME INTERACTING FACTOR 4 (PIF4). In this opinion article we discuss the mechanisms of PIF4-mediated acclimation to increased ambient temperature with focus on timing of flowering and morphological acclimation.

  2. High temperature erosion of nickel alloys

    SciTech Connect

    Zhou, J.

    1995-12-31

    High temperature erosion behavior was studied on three commercial nickel alloys, Inconel 718, Inconel 601 and Inconel X-750, using a vertical sand-blast type of erosion test rig. Effect of temperature on erosion was investigated by varying test temperature in six steps from ambient up to 800 C. Other erosion variables investigated included impingement angle, changed from 10{degree} to 90{degree}, and impingement velocity, covered a range of 40 to 90 m/s. Extensive studies on erosion surface morphological features were done on eroded or eroded-corroded specimen surfaces using scanning electron microscopy. Thermogravimetric analysis and scratch test revealed corrosion rate, characteristics of oxide scale formed at high temperature, and some effects of corrosion on erosion. It was found that variation of erosion rate with temperature was directly related to temperature-dependent mechanical property changes of the materials. The mechanisms of the high-temperature erosion were analyzed based on test results. It was observed that erosion was dominant in temperature range up to 800 C, while corrosion played increased roles in upper portion of the temperature range tested.

  3. High temperature thermometric phosphors for use in a temperature sensor

    DOEpatents

    Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

    1998-01-01

    A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.(y), wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

  4. High temperature thermometric phosphors for use in a temperature sensor

    DOEpatents

    Allison, S.W.; Cates, M.R.; Boatner, L.A.; Gillies, G.T.

    1998-03-24

    A high temperature phosphor consists essentially of a material having the general formula LuPO{sub 4}:Dy{sub (x)},Eu{sub (y)}, wherein: 0.1 wt %{<=}x{<=}20 wt % and 0.1 wt %{<=}y{<=}20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopant. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions. 2 figs.

  5. Electrical Properties Of Capacitors At High Temperatures

    NASA Technical Reports Server (NTRS)

    Baumann, E. D.; Myers, I. T.; Overton, E.; Hammoud, A. N.

    1994-01-01

    Brief report describes results of experiments in which capacitance and dielectric loss of glass, metallized-polytetrafluoroethylene, and solid-tantalum capacitor measured at temperatures from 20 degrees C to 200 degrees C. Conclusions drawn concerning suitability of capacitors for use at high temperatures; such as in nuclear powerplants, aircraft, equipment for extracting geothermal energy, switching power supplies, and automotive integrated engine electronics.

  6. High temperature ceramic/metal joint structure

    DOEpatents

    Boyd, Gary L.

    1991-01-01

    A high temperature turbine engine includes a hybrid ceramic/metallic rotor member having ceramic/metal joint structure. The disclosed joint is able to endure higher temperatures than previously possible, and aids in controlling heat transfer in the rotor member.

  7. High temperature superconductor materials and applications

    NASA Technical Reports Server (NTRS)

    Doane, George B., III.; Banks, Curtis; Golben, John

    1990-01-01

    Research on processing methods leading to a significant enhancement in the critical current densities (Jc) and the critical temperature (Tc) of high temperature superconducting in thin bulk and thin film forms. The fabrication of important devices for NASA unique applications (sensors) is investigated.

  8. Processing Techniques Developed to Fabricate Lanthanum Titanate Piezoceramic Material for High-Temperature Smart Structures

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.; Farmer, Serene C.; Sayir, Ali

    2004-01-01

    Piezoelectric ceramic materials are potential candidates for use as actuators and sensors in intelligent gas turbine engines. For piezoceramics to be applied in gas turbine engines, they will have to be able to function in temperatures ranging from 1000 to 2500 F. However, the maximum use temperature for state-of-the-art piezoceramic materials is on the order of 300 to 400 F. Research activities have been initiated to develop high-temperature piezoceramic materials for gas turbine engine applications. Lanthanum titanate has been shown to have high-temperature piezoelectric properties with Curie temperatures of T(sub c) = 1500 C and use temperatures greater than 1000 C. However, the fabrication of lanthanum titanate poses serious challenges because of the very high sintering temperatures required for densification. Two different techniques have been developed at the NASA Glenn Research Center to fabricate dense lanthanum titanate piezoceramic material. In one approach, lower sintering temperatures were achieved by adding yttrium oxide to commercially available lanthanum titanate powder. Addition of only 0.1 mol% yttrium oxide lowered the sintering temperature by as much as 300 C, to just 1100 C, and dense lanthanum titanate was produced by pressure-assisted sintering. The second approach utilized the same commercially available powders but used an innovative sintering approach called differential sintering, which did not require any additive.

  9. High richness and dense seeding enhance grassland restoration establishment but have little effect on drought response.

    PubMed

    Carter, Daniel L; Blair, John M

    2012-06-01

    Restorations commonly utilize seed addition to formerly arable lands where the development of native plant communities is severely dispersal limited. However, variation in seed addition practices may profoundly affect restoration outcomes. Theory and observations predict that species-rich seed mixtures and seeding at high densities should enhance native plant community establishment, minimize exotic species cover, and may promote resistance and resilience to, and recovery from, environmental perturbations. We studied the post-seeding establishment of native plant communities in large grassland restoration plots, which were sown at two densities crossed with two levels of species richness on formerly arable land in Nebraska, USA, and their responses to drought. To evaluate drought resistance, recovery, and resilience of restored plant communities, we erected rainfall manipulation structures and tracked the response of seeded species cover and total plant biomass during experimental drought relative to controls and in the post-drought growing season. High seed richness and high-density seeding treatments resulted in greater richness and cover of native, seeded species per 0.5 m2 compared to low-richness and low-density treatments. Cover differences in response to seed mixture richness were driven by native forbs. Richness and cover of exotic species were lowest in high-richness and high-density treatments. We found little evidence of differential drought resistance, recovery, and resilience among seeding treatments. Increases in exotic species across years were restricted to drought subplots, and were not affected by seeding treatments. Grassland restoration was generally enhanced and exotic cover reduced both by the use of high-richness seed mixtures and high-density seeding. Given the lack of restoration treatment effects on the resistance, recovery, or resilience of seeded species exposed to drought, and the increases in exotic species following drought, other

  10. High richness and dense seeding enhance grassland restoration establishment but have little effect on drought response.

    PubMed

    Carter, Daniel L; Blair, John M

    2012-06-01

    Restorations commonly utilize seed addition to formerly arable lands where the development of native plant communities is severely dispersal limited. However, variation in seed addition practices may profoundly affect restoration outcomes. Theory and observations predict that species-rich seed mixtures and seeding at high densities should enhance native plant community establishment, minimize exotic species cover, and may promote resistance and resilience to, and recovery from, environmental perturbations. We studied the post-seeding establishment of native plant communities in large grassland restoration plots, which were sown at two densities crossed with two levels of species richness on formerly arable land in Nebraska, USA, and their responses to drought. To evaluate drought resistance, recovery, and resilience of restored plant communities, we erected rainfall manipulation structures and tracked the response of seeded species cover and total plant biomass during experimental drought relative to controls and in the post-drought growing season. High seed richness and high-density seeding treatments resulted in greater richness and cover of native, seeded species per 0.5 m2 compared to low-richness and low-density treatments. Cover differences in response to seed mixture richness were driven by native forbs. Richness and cover of exotic species were lowest in high-richness and high-density treatments. We found little evidence of differential drought resistance, recovery, and resilience among seeding treatments. Increases in exotic species across years were restricted to drought subplots, and were not affected by seeding treatments. Grassland restoration was generally enhanced and exotic cover reduced both by the use of high-richness seed mixtures and high-density seeding. Given the lack of restoration treatment effects on the resistance, recovery, or resilience of seeded species exposed to drought, and the increases in exotic species following drought, other

  11. Assigning thermodynamic temperatures to high-temperature fixed-points

    NASA Astrophysics Data System (ADS)

    Woolliams, E. R.; Bloembergen, P.; Machin, G.

    2013-09-01

    Workpackage five of the High Temperature Fixed-Point research programme will determine the thermodynamic temperature for the equilibrium melting transition of the pure eutectic systems of Re-C, Pt-C and Co-C and, in addition, the freezing point of Cu. Measurements of four different cells of each type will be made by nine participating laboratories. This paper describes how the melt sensitivity to the rate of the previous freeze, furnace effects and cell impurities will be accounted for and how the results will be combined allowing for all existing correlations.

  12. Passive cavity surface-emitting lasers: option of temperature-insensitive lasing wavelength for uncooled dense wavelength division multiplexing systems

    NASA Astrophysics Data System (ADS)

    Shchukin, V. A.; Ledentsov, N. N.; Slight, T.; Meredith, W.; Gordeev, N. Y.; Nadtochy, A. M.; Payusov, A. S.; Maximov, M. V.; Blokhin, S. A.; Blokhin, A. A.; Zadiranov, Yu. M.; Maleev, N. A.; Ustinov, V. M.; Choquette, K. D.

    2016-03-01

    A concept of passive cavity surface-emitting laser is proposed aimed to control the temperature shift of the lasing wavelength. The device contains an all-semiconductor bottom distributed Bragg reflector (DBR), in which the active medium is placed, a dielectric resonant cavity and a dielectric top DBR, wherein at least one of the dielectric materials has a negative temperature coefficient of the refractive index, dn/dT < 0. This is shown to be the case for commonly used dielectric systems SiO2/TiO2 and SiO2/Ta2O5. Two SiO2/TiO2 resonant structures having a cavity either of SiO2 or TiO2 were deposited on a substrate, their optical power reflectance spectra were measured at various temperatures, and refractive index temperature coefficients were extracted, dn/dT = 0.0021 K-1 for SiO2 and dn/dT = -0.0092 K-1 for TiO2. Using such dielectric materials allows designing passive cavity surface-emitting lasers having on purpose either positive, or zero, or negative temperature shift of the lasing wavelength dλ/dT. A design for temperature-insensitive lasing wavelength (dλ/dT = 0) is proposed. Employing devices with temperature-insensitive lasing wavelength in wavelength division multiplexing systems may allow significant reducing of the spectral separation between transmission channels and an increase in number of channels for a defined spectral interval enabling low cost energy efficient uncooled devices.

  13. High-Temperature Optical Window Design

    NASA Technical Reports Server (NTRS)

    Roeloffs, Norman; Taranto, Nick

    1995-01-01

    A high-temperature optical window is essential to the optical diagnostics of high-temperature combustion rigs. Laser Doppler velocimetry, schlieren photography, light sheet visualization, and laser-induced fluorescence spectroscopy are a few of the tests that require optically clear access to the combustor flow stream. A design was developed for a high-temperature window that could withstand the severe environment of the NASA Lewis 3200 F Lean Premixed Prevaporized (LPP) Flame Tube Test Rig. The development of this design was both time consuming and costly. This report documents the design process and the lessons learned, in an effort to reduce the cost of developing future designs for high-temperature optical windows.

  14. A sharp knife for high temperatures

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.

    1978-01-01

    Electrically heated nickel-chrome-steel alloy knife may be used to cut heat resistant plastic felt and similar materials with relative ease. Blade made of commercially available alloy RA 330 retains edge at temperatures as high as 927 C.

  15. Measuring Moduli Of Elasticity At High Temperatures

    NASA Technical Reports Server (NTRS)

    Wolfenden, Alan

    1993-01-01

    Shorter, squatter specimens and higher frequencies used in ultrasonic measurement technique. Improved version of piezo-electric ultrasonic composite oscillator technique used to measure moduli of elasticity of solid materials at high temperatures.

  16. Silicon carbide, an emerging high temperature semiconductor

    NASA Technical Reports Server (NTRS)

    Matus, Lawrence G.; Powell, J. Anthony

    1991-01-01

    In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed.

  17. High-temperature superconductivity: A conventional conundrum

    DOE PAGES

    Božović, Ivan

    2016-01-07

    High-temperature superconductivity in ultrathin films of iron selenide deposited on strontium titanate has been attributed to various exotic mechanisms, and new experiments indicate that it may be conventional, with broader implications.

  18. The Conference on High Temperature Electronics

    NASA Technical Reports Server (NTRS)

    Hamilton, D. J.; Mccormick, J. B.; Kerwin, W. J.; Narud, J. A.

    1981-01-01

    The status of and directions for high temperature electronics research and development were evaluated. Major objectives were to (1) identify common user needs; (2) put into perspective the directions for future work; and (3) address the problem of bringing to practical fruition the results of these efforts. More than half of the presentations dealt with materials and devices, rather than circuits and systems. Conference session titles and an example of a paper presented in each session are (1) User requirements: High temperature electronics applications in space explorations; (2) Devices: Passive components for high temperature operation; (3) Circuits and systems: Process characteristics and design methods for a 300 degree QUAD or AMP; and (4) Packaging: Presently available energy supply for high temperature environment.

  19. Altering high temperature subterranean formation permeability

    SciTech Connect

    Moradi-Araghi, A.

    1991-02-19

    This patent describes a delayed acrylamide containing polymer crosslinker having stability in an aqueous solution at high temperatures. It comprises: a combination of an aldehyde and a salicylic acid derivative selected from salicylamide and acetysalicylic acid.

  20. Optimum angle-cut of collimator for dense objects in high-energy proton radiography

    NASA Astrophysics Data System (ADS)

    Xu, Hai-Bo; Zheng, Na

    2016-02-01

    The use of minus identity lenses with an angle-cut collimator can achieve high contrast images in high-energy proton radiography. This article presents the principles of choosing the angle-cut aperture of the collimator for different energies and objects. Numerical simulation using the Monte Carlo code Geant4 has been implemented to investigate the entire radiography for the French test object. The optimum angle-cut apertures of the collimators are also obtained for different energies. Supported by NSAF (11176001) and Science and Technology Developing Foundation of China Academy of Engineering Physics (2012A0202006)

  1. Materials for high-temperature thermoelectric conversion

    NASA Technical Reports Server (NTRS)

    Feigelson, R. S.; Elwell, D.; Auld, B. A.

    1984-01-01

    The development of materials for high temperature thermoelectric energy conversion devices was investigated. The development of new criteria for the selection of materials which is based on understanding of the fundamental principles governing the behavior of high temperature thermoelectric materials is discussed. The synthesis and characterization of promising new materials and the growth of single crystals to eliminate possible problems associated with grain boundaries and other defects in polycrystalline materials are outlined.

  2. PLA recycling by hydrolysis at high temperature

    NASA Astrophysics Data System (ADS)

    Cristina, Annesini Maria; Rosaria, Augelletti; Sara, Frattari; Fausto, Gironi

    2016-05-01

    In this work the process of PLA hydrolysis at high temperature was studied, in order to evaluate the possibility of chemical recycling of this polymer bio-based. In particular, the possibility to obtain the monomer of lactic acid from PLA degradation was investigated. The results of some preliminary tests, performed in a laboratory batch reactor at high temperature, are presented: the experimental results show that the complete degradation of PLA can be obtained in relatively low reaction times.

  3. Recent developments in high temperature organic polymers

    NASA Technical Reports Server (NTRS)

    Hergenrother, P. M.

    1991-01-01

    Developments in high temperature organic polymers during the last 5 years with major emphasis on polyimides and poly(arylene ether)s are discussed. Specific polymers or series of polymers have been selected to demonstrate unique properties or the effect chemical structure has upon certain properties. This article is not intended to be a comprehensive review of high temperature polymer advancements during the last 5 years.

  4. High temperature structural fibers: Status and needs

    NASA Technical Reports Server (NTRS)

    Dicarlo, James A.

    1991-01-01

    The key to high temperature structural composites is the selection and incorporation of continuous fiber reinforcement with optimum mechanical, physical, and chemical properties. Critical fiber property needs are high strength, high stiffness, and retention of these properties during composite fabrication and use. However, unlike polymeric composites where all three requirements are easily achieved with a variety of commercially available carbon-based fibers, structural fibers with sufficient stiffness and strength retention for high temperature metal, intermetallic, and ceramic composites are not available. The objective here is to discuss in a general manner the thermomechanical stability problem for current high performance fibers which are based on silicon and alumina compositions. This is accomplished by presenting relevant fiber property data with a brief discussion of potential underlying mechanisms. From this general overview, some possible materials engineering approaches are suggested which may lead to minimization and/or elimination of this critical stability problem for current high temperature fibers.

  5. Apparatus and method for high temperature viscosity and temperature measurements

    DOEpatents

    Balasubramaniam, Krishnan; Shah, Vimal; Costley, R. Daniel; Singh, Jagdish P.

    2001-01-01

    A probe for measuring the viscosity and/or temperature of high temperature liquids, such as molten metals, glass and similar materials comprises a rod which is an acoustical waveguide through which a transducer emits an ultrasonic signal through one end of the probe, and which is reflected from (a) a notch or slit or an interface between two materials of the probe and (b) from the other end of the probe which is in contact with the hot liquid or hot melt, and is detected by the same transducer at the signal emission end. To avoid the harmful effects of introducing a thermally conductive heat sink into the melt, the probe is made of relatively thermally insulative (non-heat-conductive) refractory material. The time between signal emission and reflection, and the amplitude of reflections, are compared against calibration curves to obtain temperature and viscosity values.

  6. Quasipermanent magnets of high temperature superconductor - Temperature dependence

    NASA Technical Reports Server (NTRS)

    Chen, In-Gann; Liu, Jianxiong; Ren, Yanru; Weinstein, Roy; Kozlowski, Gregory; Oberly, Charles E.

    1993-01-01

    We report on persistent field in quasi-permanent magnets of high temperature superconductors. Magnets composed of irradiated Y(1+)Ba2Cu3O7 trapped field Bt = 1.52 T at 77 K and 1.9 T at lower temperature. However, the activation magnet limited Bt at lower temperature. We present data on Jc(H,T) for unirradiated materials, and calculate Bt at various T. Based upon data at 65 K, we calculate Bt in unirradiated single grains at 20 K and find that 5.2 T will be trapped for grain diameter d about 1.2 cm, and 7.9 T for d = 2.3 cm. Irradiated grains will trap four times these values.

  7. Ionization of NO at high temperature

    NASA Technical Reports Server (NTRS)

    Hansen, C. Frederick

    1991-01-01

    Space vehicles flying through the atmosphere at high speed are known to excite a complex set of chemical reactions in the atmospheric gases, ranging from simple vibrational excitation to dissociation, atom exchange, electronic excitation, ionization, and charge exchange. Simple arguments are developed for the temperature dependence of the reactions leading to ionization of NO, including the effect of vibrational electronic thermal nonequilibrium. NO ionization is the most important source of electrons at intermediate temperatures and at higher temperatures provides the trigger electrons that ionize atoms. Based on these arguments, recommendations are made for formulae which fit observed experimental results, and which include a dependence on both a heavy particle temperature and different vibration electron temperatures. In addition, these expressions will presumably provide the most reliable extrapolation of experimental results to much higher temperatures.

  8. Towards ultrahigh volumetric capacitance: graphene derived highly dense but porous carbons for supercapacitors

    PubMed Central

    Tao, Ying; Xie, Xiaoying; Lv, Wei; Tang, Dai-Ming; Kong, Debin; Huang, Zhenghong; Nishihara, Hirotomo; Ishii, Takafumi; Li, Baohua; Golberg, Dmitri; Kang, Feiyu; Kyotani, Takashi; Yang, Quan-Hong

    2013-01-01

    A small volumetric capacitance resulting from a low packing density is one of the major limitations for novel nanocarbons finding real applications in commercial electrochemical energy storage devices. Here we report a carbon with a density of 1.58 g cm−3, 70% of the density of graphite, constructed of compactly interlinked graphene nanosheets, which is produced by an evaporation-induced drying of a graphene hydrogel. Such a carbon balances two seemingly incompatible characteristics: a porous microstructure and a high density, and therefore has a volumetric capacitance for electrochemical capacitors (ECs) up to 376 F cm−3, which is the highest value so far reported for carbon materials in an aqueous electrolyte. More promising, the carbon is conductive and moldable, and thus could be used directly as a well-shaped electrode sheet for the assembly of a supercapacitor device free of any additives, resulting in device-level high energy density ECs. PMID:24131954

  9. High temperature crystalline superconductors from crystallized glasses

    DOEpatents

    Shi, Donglu

    1992-01-01

    A method of preparing a high temperature superconductor from an amorphous phase. The method involves preparing a starting material of a composition of Bi.sub.2 Sr.sub.2 Ca.sub.3 Cu.sub.4 Ox or Bi.sub.2 Sr.sub.2 Ca.sub.4 Cu.sub.5 Ox, forming an amorphous phase of the composition and heat treating the amorphous phase for particular time and temperature ranges to achieve a single phase high temperature superconductor.

  10. Warm Dense Matter: An Overview

    SciTech Connect

    Kalantar, D H; Lee, R W; Molitoris, J D

    2004-04-21

    This document provides a summary of the ''LLNL Workshop on Extreme States of Materials: Warm Dense Matter to NIF'' which was held on 20, 21, and 22 February 2002 at the Wente Conference Center in Livermore, CA. The warm dense matter regime, the transitional phase space region between cold material and hot plasma, is presently poorly understood. The drive to understand the nature of matter in this regime is sparking scientific activity worldwide. In addition to pure scientific interest, finite temperature dense matter occurs in the regimes of interest to the SSMP (Stockpile Stewardship Materials Program). So that obtaining a better understanding of WDM is important to performing effective experiments at, e.g., NIF, a primary mission of LLNL. At this workshop we examined current experimental and theoretical work performed at, and in conjunction with, LLNL to focus future activities and define our role in this rapidly emerging research area. On the experimental front LLNL plays a leading role in three of the five relevant areas and has the opportunity to become a major player in the other two. Discussion at the workshop indicated that the path forward for the experimental efforts at LLNL were two fold: First, we are doing reasonable baseline work at SPLs, HE, and High Energy Lasers with more effort encouraged. Second, we need to plan effectively for the next evolution in large scale facilities, both laser (NIF) and Light/Beam sources (LCLS/TESLA and GSI) Theoretically, LLNL has major research advantages in areas as diverse as the thermochemical approach to warm dense matter equations of state to first principles molecular dynamics simulations. However, it was clear that there is much work to be done theoretically to understand warm dense matter. Further, there is a need for a close collaboration between the generation of verifiable experimental data that can provide benchmarks of both the experimental techniques and the theoretical capabilities. The conclusion of this

  11. Dense and Homogeneous Compaction of Fine Ceramic and Metallic Powders: High-Speed Centrifugal Compaction Process

    SciTech Connect

    Suzuki, Hiroyuki Y.

    2008-02-15

    High-Speed Centrifugal Compaction Process (HCP) is a variation of colloidal compacting method, in which the powders sediment under huge centrifugal force. Compacting mechanism of HCP differs from conventional colloidal process such as slip casting. The unique compacting mechanism of HCP leads to a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, flawless microstructure of the green compacts, etc. However, HCP also has several deteriorative characteristics that must be overcome to fully realize this process' full potential.

  12. High Temperature, Wireless Seismometer Sensor for Venus

    NASA Technical Reports Server (NTRS)

    Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Meredith, Roger D.; Beheim, Glenn M.; Hunter Gary W.; Kiefer, Walter S.

    2012-01-01

    Space agency mission plans state the need to measure the seismic activity on Venus. Because of the high temperature on Venus (462? C average surface temperature) and the difficulty in placing and wiring multiple sensors using robots, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents the description and proof of concept measurements of a high temperature, wireless seismometer sensor for Venus. A variation in inductance of a coil caused by the movement of an aluminum probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 700 Hz in the transmitted signal from the oscillator/sensor system at 426? C. This result indicates that the concept may be used on Venus.

  13. Pressure-induced metallization of dense (H₂S)₂H₂ with high-Tc superconductivity.

    PubMed

    Duan, Defang; Liu, Yunxian; Tian, Fubo; Li, Da; Huang, Xiaoli; Zhao, Zhonglong; Yu, Hongyu; Liu, Bingbing; Tian, Wenjing; Cui, Tian

    2014-01-01

    The high pressure structures, metallization, and superconductivity of recently synthesized H2-containing compounds (H2S)2H2 are elucidated by ab initio calculations. The ordered crystal structure with P1 symmetry is determined, supported by the good agreement between theoretical and experimental X-ray diffraction data, equation of states, and Raman spectra. The Cccm structure is favorable with partial hydrogen bond symmetrization above 37 GPa. Upon further compression, H2 molecules disappear and two intriguing metallic structures with R3m and Im-3m symmetries are reconstructive above 111 and 180 GPa, respectively. The predicted metallization pressure is 111 GPa, which is approximately one-third of the currently suggested metallization pressure of bulk molecular hydrogen. Application of the Allen-Dynes-modified McMillan equation for the Im-3m structure yields high Tc values of 191 K to 204 K at 200 GPa, which is among the highest values reported for H2-rich van der Waals compounds and MH3 type hydride thus far.

  14. High-entropy alloys as high-temperature thermoelectric materials

    SciTech Connect

    Shafeie, Samrand; Guo, Sheng; Hu, Qiang; Fahlquist, Henrik; Erhart, Paul; Palmqvist, Anders

    2015-11-14

    Thermoelectric (TE) generators that efficiently recycle a large portion of waste heat will be an important complementary energy technology in the future. While many efficient TE materials exist in the lower temperature region, few are efficient at high temperatures. Here, we present the high temperature properties of high-entropy alloys (HEAs), as a potential new class of high temperature TE materials. We show that their TE properties can be controlled significantly by changing the valence electron concentration (VEC) of the system with appropriate substitutional elements. Both the electrical and thermal transport properties in this system were found to decrease with a lower VEC number. Overall, the large microstructural complexity and lower average VEC in these types of alloys can potentially be used to lower both the total and the lattice thermal conductivity. These findings highlight the possibility to exploit HEAs as a new class of future high temperature TE materials.

  15. High-entropy alloys as high-temperature thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Shafeie, Samrand; Guo, Sheng; Hu, Qiang; Fahlquist, Henrik; Erhart, Paul; Palmqvist, Anders

    2015-11-01

    Thermoelectric (TE) generators that efficiently recycle a large portion of waste heat will be an important complementary energy technology in the future. While many efficient TE materials exist in the lower temperature region, few are efficient at high temperatures. Here, we present the high temperature properties of high-entropy alloys (HEAs), as a potential new class of high temperature TE materials. We show that their TE properties can be controlled significantly by changing the valence electron concentration (VEC) of the system with appropriate substitutional elements. Both the electrical and thermal transport properties in this system were found to decrease with a lower VEC number. Overall, the large microstructural complexity and lower average VEC in these types of alloys can potentially be used to lower both the total and the lattice thermal conductivity. These findings highlight the possibility to exploit HEAs as a new class of future high temperature TE materials.

  16. High dense structure boosts stability of antiferroelectric phase of NaNbO3 polycrystalline ceramics

    NASA Astrophysics Data System (ADS)

    Chao, Lumen; Hou, Yudong; Zheng, Mupeng; Zhu, Mankang

    2016-05-01

    For NaNbO3, its intrinsic phase transition sequence is still controversial in literature. In this paper, high-densified NaNbO3 ceramics derived from mechanochemical nanostructures presented a stabilized antiferroelectric characteristic. In addition to the Tc of 360 °C, another diffuse dielectric anomaly appeared around 100 °C, which did not vanish after O2 annealing treatment. The fine structure analysis indicated that this dielectric anomaly belongs to first order phase transition from P phase to Q phase. Moreover, even exerting the strong electric field close to breakdown value, the normal ferroelectric loops cannot be induced, proving the large free energy difference between these two phases.

  17. Fast vortex core switching at high temperatures

    NASA Astrophysics Data System (ADS)

    Lebecki, Kristof M.; Legut, Dominik

    2016-08-01

    Fast ferromagnetic vortex core switching is investigated employing micromagnetic simulations. Short pulse (in the range of a few hundreds of picoseconds) of an in-plane oscillating magnetic field is applied to a thin disk (diameter 200 nm and thickness 20 nm) with material parameters resembling permalloy. Fundamental frequency of this excitation field is close to the resonance with the material spin waves. Thermal effects are introduced by replacing the Landau-Lifshitz-Gilbert equation by the Landau-Lifshitz-Bloch equation. Temperature from 300 K to 850 K is considered, just below the Curie temperature TC = 870 K. Calculations are done within the OOMMF simulation framework. We find that: (i) Period of the field necessary to switch the vortex increases approximately from 141 ps at 300 K to 572 ps for the high-temperature limit. (ii) Amplitude of the field necessary to switch the vortex core decreases roughly from 60 mT to 15 mT - even at high temperatures this amplitude is nonzero, contrary to the case of quasi-static switching. (iii) Time span between the excitation and switching (switching time) seems not to depend on the temperature. (iv) Duration of the switching itself (movement of the Bloch point in the sample) increases from a few picoseconds at low temperatures to tens of picoseconds at high temperatures.

  18. Improved long-term electrical stability of pulsed high-power diodes using dense carbon fiber velvet cathodes

    SciTech Connect

    Yang Jie; Shu Ting; Wang Hui

    2012-07-15

    The influence of fibrous velvet cathodes on the electrical stability of a planar high-power diode powered by a {approx}230 kV, {approx}110 ns pulse has been investigated. The current density was on the order of {approx}123 A/cm{sup 2}. A combination of time-resolved electrical and optical diagnostics has been employed to study the basic phenomenology of the temporal and spatial evolution of the diode plasmas. Additionally, an impedance model was used to extract information about this plasma from voltage and current profiles. The results from the two diagnostics were compared. By comparison with commercial polymer velvet cathode, the dense carbon fiber velvet cathode showed superior long-term electrical stability as judged by the change in cathode turn-on field, ignition delays, diode impedance, and surface plasma characteristics during the voltage flattop, a promising result for applications where reliable operation at high power is required. Finally, it was shown that the interaction of the electron beam with the stainless steel anode did not lead to the formation of anode plasma. These results may be of interest to the high power microwave systems with cold cathodes.

  19. High-performance flexible all-solid-state supercapacitors based on densely-packed graphene/polypyrrole nanoparticle papers

    NASA Astrophysics Data System (ADS)

    Yang, Chao; Zhang, Liling; Hu, Nantao; Yang, Zhi; Wei, Hao; Wang, Yanyan; Zhang, Yafei

    2016-11-01

    Graphene-based all-solid-state supercapacitors (ASSSCs) have received increasing attention. It's a great challenge to fabricate high-performance flexible solid-state supercapacitors with high areal and volumetric energy storage capability, superior electron and ion conductivity, robust mechanical flexibility, as well as long term stability. Herein, we report a facile method to fabricate flexible ASSSCs based on densely-packed reduced graphene oxide (rGO)/polypyrrole nanoparticle (PPy NP) hybrid papers with a sandwich framework, which consists of well-separated and continuously-aligned rGO sheets. The incorporation of PPy NPs not only provides pseudocapacitance but also facilitates the infiltration of gel electrolyte. The assembled ASSSCs possess maximum areal and volumetric specific capacitances of 477 mF/cm2 and 94.9 F/cm3 at 0.5 mA/cm2. They also exhibit little capacitance deviation under different bending states, excellent cycling stability, small leakage current and low self-discharge characteristics. Additionally, the maximum areal and volumetric energy densities of 132.5 μWh/cm2 and 26.4 mWh/cm3 are achieved, which indicate that this hybrid paper is a promising candidate for high-performance flexible energy storage devices.

  20. High-temperature testing of high performance fiber reinforced concrete

    NASA Astrophysics Data System (ADS)

    Fořt, Jan; Vejmelková, Eva; Pavlíková, Milena; Trník, Anton; Čítek, David; Kolísko, Jiří; Černý, Robert; Pavlík, Zbyšek

    2016-06-01

    The effect of high-temperature exposure on properties of High Performance Fiber Reinforced Concrete (HPFRC) is researched in the paper. At first, reference measurements are done on HPFRC samples without high-temperature loading. Then, the HPFRC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000 °C. For the temperature loaded samples, measurement of residual mechanical and basic physical properties is done. Linear thermal expansion coefficient as function of temperature is accessed on the basis of measured thermal strain data. Additionally, simultaneous difference scanning calorimetry (DSC) and thermogravimetry (TG) analysis is performed in order to observe and explain material changes at elevated temperature. It is found that the applied high temperature loading significantly increases material porosity due to the physical, chemical and combined damage of material inner structure, and negatively affects also the mechanical strength. Linear thermal expansion coefficient exhibits significant dependence on temperature and changes of material structure. The obtained data will find use as input material parameters for modelling the damage of HPFRC structures exposed to the fire and high temperature action.

  1. Price and maternal obesity influence purchasing of low- and high-energy-dense foods2

    PubMed Central

    Epstein, Leonard H; Dearing, Kelly K; Paluch, Rocco A; Roemmich, James N; Cho, David

    2007-01-01

    Background Price can influence food purchases, which can influence consumption. Limited laboratory research has assessed the effect of price changes on food purchases, and no research on individual differences that may interact with price to influence purchases exists. Objective We aimed to assess the influence of price changes of low-energy-density (LED) and high-energy-density (HED) foods on mother’s food purchases in a laboratory food-purchasing analogue. Design Mothers were randomly assigned to price conditions in which the price of either LED or HED foods was manipulated from 75% to 125% of the reference purchase price, whereas the price of the alternative foods was kept at the reference value. Mothers completed purchases for 2 income levels ($15 or $30 per family member). Results Purchases were reduced when prices of LED (P < 0.01) and HED (P < 0.001) foods were increased. Maternal BMI interacted with price to influence purchases of HED foods when the price of HED foods increased (P = 0.016) and interacted with price to influence purchases of LED foods when the price of HED foods increased (P = 0.008). Conclusion These results show the relevance of considering price change as a way to influence food purchases of LED compared with HED foods and the possibility that individual differences may influence the own-price elasticity of HED foods and substitution of LED for HED foods. PMID:17921365

  2. High Temperature Calibration Furnace System user's guide

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The High Temperature Calibration Furnace System (HTCFS) was developed by Summitec Corporation. It is a high precision instrument providing a constant temperature which can be used to calibrate high temperature thermocouples. Incorporating the many recent technological advances from the fields of optical fiber thermometry, material science, computer systems interfacing, and process control, the engineers at Summitec Corporation have been able to create a system that can reach a steady operating temperature of 1700 C. The precision for the system requires the measurement of temperature to be within 1 C in two hours and within 2 C in 24 hours. As documented, the experimental result shows that this system has been able to stay within .5 C in 5 hours. No other systems commercially available have been able to achieve such high temperature precision. This manual provides an overview of the system design, instructions for instrument setup, and operation procedures. Also included are a vendor list and the source codes for the custom-designed software.

  3. High Temperature VARTM of Phenylethynyl Terminated Imides

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Watson, Kent A.; Cano, Roberto J.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.

    2009-01-01

    LaRC phenylethynyl terminated imide (PETI) resins were processed into composites using high temperature vacuum assisted resin transfer molding (VARTM). Although initial runs yielded composites with high void content, process modifications reduced voids to <3%. Photomicrographs were taken and void contents and T(sub g)s of the panels were determined.

  4. High-temperature helium-loop facility

    SciTech Connect

    Tokarz, R.D.

    1981-09-01

    The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100/sup 0/F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system.

  5. Study of high temperature oxide superconductors

    NASA Astrophysics Data System (ADS)

    Wu, M. K.; Ashburn, J. R.; Higgins, C. A.; Carswell, W. E.; Loo, B. H.; Burns, D. H.; Ibrahim, A.; Rolin, T.; Peters, P. N.; Sisk, R. C.

    1988-01-01

    Experimental studies are reported whose results indicate that proper processing procedures are critical to the formation of high-temperature copper oxide superconductors. Superconducting 123 films can be fabricated using the green 211 phase as a substrate. The transition temperature and transition width characteristics of these films are better than those obtained when other oxide compounds are used as substrates. A compact or single-crystal 211 phase will be desirable as a substrate for high-quality thin films. A new high T(c) copper oxide compound with nonrare earth elements was prepared using high-temperature processing. A YBa2Cu3O7-Ag composite with improved electrical conductivity was also prepared.

  6. High-temperature bulk acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Fritze, Holger

    2011-01-01

    Piezoelectric crystals like langasite (La3Ga5SiO14, LGS) and gallium orthophosphate (GaPO4) exhibit piezoelectrically excited bulk acoustic waves at temperatures of up to at least 1450 °C and 900 °C, respectively. Consequently, resonant sensors based on those materials enable new sensing approaches. Thereby, resonant high-temperature microbalances are of particular interest. They correlate very small mass changes during film deposition onto resonators or gas composition-dependent stoichiometry changes of thin films already deposited onto the resonators with the resonance frequency shift of such devices. Consequently, the objective of the work is to review the high-temperature properties, the operation limits and the measurement principles of such resonators. The electromechanical properties of high-temperature bulk acoustic wave resonators such as mechanical stiffness, piezoelectric and dielectric constant, effective viscosity and electrical conductivity are described using a one-dimensional physical model and determined accurately up to temperatures as close as possible to their ultimate limit. Insights from defect chemical models are correlated with the electromechanical properties of the resonators. Thereby, crucial properties for stable operation as a sensor under harsh conditions are identified to be the formation of oxygen vacancies and the bulk conductivity. Operation limits concerning temperature, oxygen partial pressure and water vapor pressure are given. Further, application-relevant aspects such as temperature coefficients, temperature compensation and mass sensitivity are evaluated. In addition, approximations are introduced which make the exact model handy for routine data evaluation. An equivalent electrical circuit for high-temperature resonator devices is derived based on the one-dimensional physical model. Low- and high-temperature approximations are introduced. Thereby, the structure of the equivalent circuit corresponds to the Butterworth

  7. NDE standards for high temperature materials

    NASA Technical Reports Server (NTRS)

    Vary, Alex

    1991-01-01

    High temperature materials include monolithic ceramics for automotive gas turbine engines and also metallic/intermetallic and ceramic matrix composites for a range of aerospace applications. These are materials that can withstand extreme operating temperatures that will prevail in advanced high-efficiency gas turbine engines. High temperature engine components are very likely to consist of complex composite structures with three-dimensionality interwoven and various intermixed ceramic fibers. The thermomechanical properties of components made of these materials are actually created in-place during processing and fabrication stages. The complex nature of these new materials creates strong incentives for exact standards for unambiguous evaluations of defects and microstructural characteristics. NDE techniques and standards that will ultimately be applicable to production and quality control of high temperature materials and structures are still emerging. The needs range from flaw detection to below 100 micron levels in monolithic ceramics to global imaging of fiber architecture and matrix densification anomalies in composites. The needs are different depending on the processing stage, fabrication method, and nature of the finished product. The standards are discussed that must be developed in concert with advances in NDE technology, materials processing research, and fabrication development. High temperature materials and structures that fail to meet stringent specifications and standards are unlikely to compete successfully either technologically or in international markets.

  8. Low temperature rate constants for the N(4S) + CH(X2Πr) reaction. Implications for N2 formation cycles in dense interstellar clouds.

    PubMed

    Daranlot, Julien; Hu, Xixi; Xie, Changjian; Loison, Jean-Christophe; Caubet, Philippe; Costes, Michel; Wakelam, Valentine; Xie, Daiqian; Guo, Hua; Hickson, Kevin M

    2013-09-01

    Rate constants for the potentially important interstellar N((4)S) + CH(X(2)Πr) reaction have been measured in a continuous supersonic flow reactor over the range 56 K ≤T≤ 296 K using the relative rate technique employing both the N((4)S) + OH(X(2)Πi) and N((4)S) + CN(X(2)Σ(+)) reactions as references. Excess concentrations of atomic nitrogen were produced by the microwave discharge method upstream of the Laval nozzle and CH and OH radicals were created by the in situ pulsed laser photolysis of suitable precursor molecules. In parallel, quantum dynamics calculations of the title reaction have been performed based on accurate global potential energy surfaces for the 1(3)A' and 1(3)A'' states of HCN and HNC, brought about through a hierarchical construction scheme. Both adiabatic potential energy surfaces are barrierless, each one having two deep potential wells suggesting that this reaction is dominated by a complex-forming mechanism. The experimental and theoretical work are in excellent agreement, predicting a positive temperature dependence of the rate constant, in contrast to earlier experimental work at low temperature. The effects of the new low temperature rate constants on interstellar N2 formation are tested using a dense cloud model, yielding N2 abundances 10-20% lower than previously predicted.

  9. How Dense!

    ERIC Educational Resources Information Center

    Codner, A. C.

    1985-01-01

    Suggests examining population density to help students understand density as a chemical concept. Simple experiments and demonstrations with carbon dioxide, burning oil, natural gas, and temperature are also suggested. (DH)

  10. MICROWAVE MEASUREMENT OF REFRACTORY MATERIALS AT HIGH-TEMPERATURE

    SciTech Connect

    Kharkovsky, S.; Zoughi, R.; Smith, J.; Davis, B.; Limmer, R.

    2009-03-03

    Knowledge of the electrical behavior of refractory materials may enable the development and optimization of microwave nondestructive techniques to detect and evaluate changes in their physical properties while the materials are in service. This paper presents the results of a limited and preliminary investigation in which two refractory materials (dense chrome and dense zircon) were subjected to increasing temperature in a furnace and in which a frequency-modulated continuous-wave radar operating in the frequency range of 8-18 GHz radar was used to evaluate their attenuation properties.

  11. High-Temperature Solar Cell Development

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.; Raffaelle, Ryne P.; Merritt, Danielle

    2004-01-01

    The vast majority of satellites and near-earth probes developed to date have relied upon photovoltaic power generation. If future missions to probe environments close to the sun will be able to use photovoltaic power, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. For example, the equilibrium temperature of a Mercury surface station will be about 450 C, and the temperature of solar arrays on the proposed "Solar Probe" mission will extend to temperatures as high as 2000 C (although it is likely that the craft will operate on stored power rather than solar energy during the closest approach to the sun). Advanced thermal design principles, such as replacing some of the solar array area with reflectors, off-pointing, and designing the cells to reflect rather than absorb light out of the band of peak response, can reduce these operating temperature somewhat. Nevertheless, it is desirable to develop approaches to high-temperature solar cell design that can operate under temperature extremes far greater than today's cells. Solar cells made from wide bandgap (WBG) compound semiconductors are an obvious choice for such an application. In order to aid in the experimental development of such solar cells, we have initiated a program studying the theoretical and experimental photovoltaic performance of wide bandgap materials. In particular, we have been investigating the use of GaP, SiC, and GaN materials for space solar cells. We will present theoretical results on the limitations on current cell technologies and the photovoltaic performance of these wide-bandgap solar cells in a variety of space conditions. We will also give an overview of some of NASA's cell developmental efforts in this area and discuss possible future mission applications.

  12. High temperature thrust chamber for spacecraft

    NASA Technical Reports Server (NTRS)

    Chazen, Melvin L. (Inventor); Mueller, Thomas J. (Inventor); Kruse, William D. (Inventor)

    1998-01-01

    A high temperature thrust chamber for spacecraft (20) is provided herein. The high temperature thrust chamber comprises a hollow body member (12) having an outer surface and an internal surface (16) defining the high temperature chamber (10). The body member (12) is made substantially of rhenium. An alloy (18) consisting of iridium and at least alloying metal selected of the group consisting of rhodium, platinum and palladium is deposited on at least a portion of the internal surface (16) of the body member (12). The iridium and the alloying metal are electrodeposited onto the body member (12). A HIP cycle is performed upon the body member (12) to cause the coating of iridium and the alloying metal to form the alloy (18) which protects the body member (12) from oxidation.

  13. High-temperature geothermal reservoir engineering

    SciTech Connect

    Schroeder, R.C.; Benson, S.; Goranson, C.

    1980-02-01

    A review of high-temperature geothermal reservoir engineering is presented. High-temperature downhole conditions encountered during field activities are reviewed with data from Cerro Prieto as the primary example. The types of measurements required for estimation of formation parameter values and how they depend on other geoscience data are reviewed. The analysis techniques that are currently used to evaluate field data are discussed and their limitations, applicability, and associated difficulties are described using data from Cerro Prieto as an example. Downhole tools that are needed for high-temperature measurements are discussed with a review of the current state of the art. The use of measured data in reservoir engineering simulation calculations is summarized, and different numerical models are reviewed. Data from Cerro Prieto are used as an example to show how reserves and reservoir depletion calculations can be used to aid the field developer in choosing operational field strategies.

  14. High Temperature Membrane & Advanced Cathode Catalyst Development

    SciTech Connect

    Protsailo, Lesia

    2006-04-20

    Current project consisted of three main phases and eighteen milestones. Short description of each phase is given below. Table 1 lists program milestones. Phase 1--High Temperature Membrane and Advanced Catalyst Development. New polymers and advanced cathode catalysts were synthesized. The membranes and the catalysts were characterized and compared against specifications that are based on DOE program requirements. The best-in-class membranes and catalysts were downselected for phase 2. Phase 2--Catalyst Coated Membrane (CCM) Fabrication and Testing. Laboratory scale catalyst coated membranes (CCMs) were fabricated and tested using the down-selected membranes and catalysts. The catalysts and high temperature membrane CCMs were tested and optimized. Phase 3--Multi-cell stack fabrication. Full-size CCMs with the down-selected and optimized high temperature membrane and catalyst were fabricated. The catalyst membrane assemblies were tested in full size cells and multi-cell stack.

  15. Low toxicity high temperature PMR polyimide

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor)

    1992-01-01

    In-situ polymerization of monomer reactants (PMR) type polyimides constitute an important class of ultra high performance composite matrix resins. PMR-15 is the best known and most widely used PMR polyimide. An object of the present invention is to provide a substantially improved high temperature PMR-15 system that exhibits better processability, toughness, and thermo-oxidative stability than PMR-15, as well as having a low toxicity. Another object is to provide new PMR polyimides that are useful as adhesives, moldings, and composite matrices. By the present invention, a new PMR polyimide comprises a mixture of the following compounds: 3,4'-oxydianiline (3,4'-ODA), NE, and BTDE which are then treated with heat. This PMR was designated LaRC-RP46 and has a broader processing window, better reproducibility of high quality composite parts, better elevated temperature mechanical properties, and higher retention of mechanical properties at an elevated temperature, particularly, at 371 C.

  16. Containerless measurements on liquids at high temperatures

    NASA Technical Reports Server (NTRS)

    Weber, Richard

    1993-01-01

    The application of containerless techniques for measurements of the thermophysical properties of high temperature liquids is reviewed. Recent results obtained in the materials research laboratories at Intersonics are also presented. Work to measure high temperature liquid properties is motivated by both the need for reliable property data for modeling of industrial processes involving molten materials and generation of data form basic modeling of materials behavior. The motivation for this work and examples of variations in thermophysical property values from the literature are presented. The variations may be attributed to changes in the specimen properties caused by chemical changes in the specimen and/or to measurement errors. The two methods used to achieve containerless conditions were aeroacoustic levitation and electromagnetic levitation. Their qualities are presented. The accompanying slides show the layout of levitation equipment and present examples of levitated metallic and ceramic specimens. Containerless techniques provide a high degree of control over specimen chemistry, nucleation and allow precise control of liquid composition to be achieved. Effects of minor additions can thus be measured in a systematic way. Operation in reduced gravity enables enhanced control of liquid motion which can allow measurement of liquid transport properties. Examples of nucleation control, the thermodynamics of oxide contamination removal, and control of the chromium content of liquid aluminum oxide by high temperature containerless processes are presented. The feasibility of measuring temperature, emissivity, liquidus temperature, enthalpy, surface tension, density, viscosity, and thermal diffusivity are discussed in the final section of the paper.

  17. Micromechanics of high temperature deformation and failure

    NASA Technical Reports Server (NTRS)

    Nasser, S. N.; Weertman, J. R.

    1985-01-01

    The micromechanics of the constitutive behavior of elastoplastic materials at high temperatures was examined. The experimental work focused on the development of microscopic defects in superalloys (Waspaloy), especially the formation of voids at grain boundary carbides, and slip induced surface cracks within grains upon cyclic loading at high temperatures. The influence of these defects on the life expectancy of the material was examined. The theoretical work consists of two parts: (1) analytical description of the mechanisms that lead to defects observed experimentally; and (2) development of macroscopic elastoplastic nonlinear constitutive relations based on mechanical modeling.

  18. Joining of ceramics for high temperature applications

    NASA Technical Reports Server (NTRS)

    Vilpas, Martti

    1987-01-01

    Summarized is a literature survey of the methods for joining ceramics to ceramics or ceramics to metals for high temperature applications. Also mechanical properties and potential applications of the joints are considered. The joining of ceramics is usually carried out by brazing or diffusion bonding. Especially the latter has been found useful, increasing the application of bonded ceramics. The possibility of using electron beam and laser beam welding for joining ceramics has also recently been investigated. The bonding of ceramics has found numerous applications typical for high operating temperatures, i.e., sensors and thermocouples.

  19. Introduction to high-temperature superconductivity

    SciTech Connect

    Sheahen, T.P.

    1994-12-31

    The Electric Power Research Institute, as part of its program to develop high-temperature superconductivity applications for the power industry, has endevoured to educate utility engineers and executives on superconductivity. This book is a series of tutorials prepared by the Argonne National Laboratory. Part one is at an introductory level, asking and answering the question `What is superconductivity?` Part 2 is an exposition of the basic properties of the new materials - structure, phase equilibria, effects of doping, etc. with consideration of theoretical issues. Part 3 covers potential practical uses of high temperature superconductors.

  20. High-temperature MAS-NMR at high spinning speeds.

    PubMed

    Kirchhain, Holger; Holzinger, Julian; Mainka, Adrian; Spörhase, Andreas; Venkatachalam, Sabarinathan; Wixforth, Achim; van Wüllen, Leo

    2016-09-01

    A low cost version to enable high temperature MAS NMR experiments at temperatures of up to 700°C and spinning speeds of up to 10kHz is presented. The method relies on inductive heating using a metal coated rotor insert. The metal coating is accomplished via a two step process involving physical vapor deposition and galvanization.

  1. Fiber Bragg Grating Filter High Temperature Sensors

    NASA Technical Reports Server (NTRS)

    Lyons, Donald R.; Brass, Eric D.; Pencil, Eric (Technical Monitor)

    2001-01-01

    We present a scaled-down method for determining high temperatures using fiber-based Bragg gratings. Bragg gratings are distributed along the length of the optical fiber, and have high reflectivities whenever the optical wavelength is twice the grating spacing. These spatially distinct Bragg regions (located in the core of a fiber) are sensitive to local temperature changes. Since these fibers are silica-based they are easily affected by localized changes in temperature, which results in changes to both the grating spacing and the wavelength reflectivity. We exploit the shift in wavelength reflectivity to measure the change in the local temperature. Note that the Bragg region (sensing area) is some distance away from where the temperature is being measured. This is done so that we can measure temperatures that are much higher than the damage threshold of the fiber. We do this by affixing the fiber with the Bragg sensor to a material with a well-known coefficient of thermal expansion, and model the heat gradient from the region of interest to the actual sensor. The research described in this paper will culminate in a working device as well as be the second portion of a publication pending submission to Optics Letters.

  2. Light Scattering on the High Temperature Superconductors

    NASA Astrophysics Data System (ADS)

    Slakey, Francis

    The high temperature superconductors have been examined by the technique of Raman scattering in several limits: the insulating phase, the normal and superconducting state of the superconducting phase, and an optically induced metastable phase. In all cases, the analysis and proposed phenomenological models involved either an examination of the inelastic background scattering or the phonon excitation spectrum. Specifically, the character, temperature dependence, critical temperature dependence and the copper-oxygen covalency dependence of the inelastic background scattering has been studied in all three phases. Analysis of the superconducting phase reveals a marginal Fermi-liquid like character of the electronic polarizability, and a decidedly non-traditional shift of the scattering intensity of the electronic excitations at low temperature. On removing oxygen, the system passes through a metal-insulator transition and the inelastic background becomes dominantly magnetic in origin. Examinations of the 'allowed' Raman active phonons in the superconducting phase expose a strong coupling of two modes to the background electronic excitation spectrum, and a dramatic renormalization of these modes below T _{rm c}. Further, two sharply resonant Raman 'forbidden' modes can be bleached out of the spectrum at low temperature with a sufficiently high laser dosage. A transition from this optically induced metastable state to the normal state occurs on warming the crystal back to room temperature. On reducing the oxygen concentration, the coupling strength of the two asymmetric phonons diminishes rapidly, the renormalization effects vanish, and the compound no longer exhibits metastability.

  3. High Temperature Mechanisms for Venus Exploration

    NASA Astrophysics Data System (ADS)

    Ji, Jerri; Narine, Roop; Kumar, Nishant; Singh, Sase; Gorevan, Steven

    Future Venus missions, including New Frontiers Venus In-Situ Explorer and three Flagship Missions - Venus Geophysical Network, Venus Mobile Explorer and Venus Surface Sample Return all focus on searching for evidence of past climate change both on the surface and in the atmospheric composition as well as in the interior dynamics of the planet. In order to achieve these goals and objectives, many key technologies need to be developed for the Venus extreme environment. These key technologies include sample acquisition systems and other high-temperature mechanisms and mobility systems capable of extended operation when directly exposed to the Venus surface or lower atmosphere environment. Honeybee Robotics has developed two types of high temperature motors, the materials and components in both motors were selected based on the requirement to survive temperatures above a minimum of 460° C, at earth atmosphere. The prototype Switched Reluctance Motor (SRM) has been operated non-continuously for over 20 hours at Venus-like conditions (460° C temperature, mostly CO2 gas environment) and it remains functional. A drilling system, actuated by two SRMs was tested in Venus-like conditions, 460° C temperature and mostly CO2 gas environment, for more than 15 hours. The drill successfully completed three tests by drilling into chalk up to 6 inches deep in each test. A first generation Brushless DC (BLDC) Motor and high temperature resolver were also tested and the feasibility of the designs was demonstrated by the extended operation of both devices under Venus-like condition. Further development of the BLDC motor and resolver continues and these devices will, ultimately, be integrated into the development of a high temperature sample acquisition scoop and high temperature joint (awarded SBIR Phase II in October, 2007). Both the SR and BLDC motors will undergo extensive testing at Venus temperature and pressure (TRL6) and are expected to be mission ready before the next New

  4. High-Temperature Capacitor Polymer Films

    NASA Astrophysics Data System (ADS)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  5. High temperature experiment for accelerator inertial fusion

    SciTech Connect

    Lee, E.P.

    1985-05-01

    The High Temperature Experiment (HTE) is intended to produce temperatures of 50 to 100 eV in solid density targets driven by heavy ion beams from a multiple beam induction linac. The fundamental variables (particle species, energy, number of beamlets, current and pulse length) must be fixed to achieve the temperature at minimum cost, subject to criteria of technical feasibility and relevance to the development of a Fusion Driver. The conceptual design begins with an assumed (radiation-limited) target temperature and uses limitations due to particle range, beamlet perveance, and target disassembly to bound the allowable values of mass number (A) and energy (E). An accelerator model is then applied to determine the minimum length accelerator, which is a guide to total cost. The accelerator model takes into account limits on transportable charge, maximum gradient, core mass per linear meter, and head-to-tail momentum variation within a pulse.

  6. High-Temperature Shape Memory Polymers

    NASA Technical Reports Server (NTRS)

    Yoonessi, Mitra; Weiss, Robert A.

    2012-01-01

    physical conformation changes when exposed to an external stimulus, such as a change in temperature. Such materials have a permanent shape, but can be reshaped above a critical temperature and fixed into a temporary shape when cooled under stress to below the critical temperature. When reheated above the critical temperature (Tc, also sometimes called the triggering or switching temperature), the materials revert to the permanent shape. The current innovation involves a chemically treated (sulfonated, carboxylated, phosphonated, or other polar function group), high-temperature, semicrystalline thermoplastic poly(ether ether ketone) (Tg .140 C, Tm = 340 C) mix containing organometallic complexes (Zn++, Li+, or other metal, ammonium, or phosphonium salts), or high-temperature ionic liquids (e.g. hexafluorosilicate salt with 1-propyl-3- methyl imidazolium, Tm = 210 C) to form a network where dipolar or ionic interactions between the polymer and the low-molecular-weight or inorganic compound forms a complex that provides a physical crosslink. Hereafter, these compounds will be referred to as "additives". The polymer is semicrystalline, and the high-melt-point crystals provide a temporary crosslink that acts as a permanent crosslink just so long as the melting temperature is not exceeded. In this example case, the melting point is .340 C, and the shape memory critical temperature is between 150 and 250 C. PEEK is an engineering thermoplastic with a high Young fs modulus, nominally 3.6 GPa. An important aspect of the invention is the control of the PEEK functionalization (in this example, the sulfonation degree), and the thermal properties (i.e. melting point) of the additive, which determines the switching temperature. Because the compound is thermoplastic, it can be formed into the "permanent" shape by conventional plastics processing operations. In addition, the compound may be covalently cross - linked after forming the permanent shape by S-PEEK by applying ionizing

  7. Research at Very High Pressures and High Temperatures

    ERIC Educational Resources Information Center

    Bundy, Francis P.

    1977-01-01

    Reviews research and apparatus utilized in the study of the states and characteristics of materials at very high temperatures and pressures. Includes three examples of the research being conducted. (SL)

  8. Bimodular high temperature planar oxygen gas sensor.

    PubMed

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  9. Bimodular high temperature planar oxygen gas sensor

    PubMed Central

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  10. Protective interlayer for high temperature solid electrolyte electrochemical cells

    DOEpatents

    Singh, P.; Vasilow, T.R.; Richards, V.L.

    1996-05-14

    The invention is comprised of an electrically conducting doped or admixed cerium oxide composition with niobium oxide and/or tantalum oxide for electrochemical devices, characterized by the general formula: Nb{sub x}Ta{sub y}Ce{sub 1{minus}x{minus}y}O{sub 2} where x is about 0.0 to 0.05, y is about 0.0 to 0.05, and x+y is about 0.02 to 0.05, and where x is preferably about 0.02 to 0.05 and y is 0, and a method of making the same is also described. This novel composition is particularly applicable in forming a protective interlayer of a high temperature, solid electrolyte electrochemical cell, characterized by a first electrode; an electrically conductive interlayer of niobium and/or tantalum doped cerium oxide deposited over at least a first portion of the first electrode; an interconnect deposited over the interlayer; a solid electrolyte deposited over a second portion of the first electrode, the first portion being discontinuous from the second portion; and, a second electrode deposited over the solid electrolyte. The interlayer is characterized as being porous and selected from the group consisting of niobium doped cerium oxide, tantalum doped cerium oxide, and niobium and tantalum doped cerium oxide or admixtures of the same. The first electrode, an air electrode, is a porous layer of doped lanthanum manganite, the solid electrolyte layer is a dense yttria stabilized zirconium oxide, the interconnect layer is a dense, doped lanthanum chromite, and the second electrode, a fuel electrode, is a porous layer of nickel-zirconium oxide cermet. The electrochemical cell can take on a plurality of shapes such as annular, planar, etc. and can be connected to a plurality of electrochemical cells in series and/or in parallel to generate electrical energy. 5 figs.

  11. Protective interlayer for high temperature solid electrolyte electrochemical cells

    DOEpatents

    Singh, Prabhakar; Vasilow, Theodore R.; Richards, Von L.

    1996-01-01

    The invention comprises of an electrically conducting doped or admixed cerium oxide composition with niobium oxide and/or tantalum oxide for electrochemical devices, characterized by the general formula: Nb.sub.x Ta.sub.y Ce.sub.1-x-y O.sub.2 where x is about 0.0 to 0.05, y is about 0.0 to 0.05, and x+y is about 0.02 to 0.05, and where x is preferably about 0.02 to 0.05 and y is 0, and a method of making the same. This novel composition is particularly applicable in forming a protective interlayer of a high temperature, solid electrolyte electrochemical cell (10), characterized by a first electrode (12); an electrically conductive interlayer (14) of niobium and/or tantalum doped cerium oxide deposited over at least a first portion (R) of the first electrode; an interconnect (16) deposited over the interlayer; a solid electrolyte (18) deposited over a second portion of the first electrode, the first portion being discontinuous from the second portion; and, a second electrode (20) deposited over the solid electrolyte. The interlayer (14) is characterized as being porous and selected from the group consisting of niobium doped cerium oxide, tantalum doped cerium oxide, and niobium and tantalum doped cerium oxide or admixtures of the same. The first electrode (12), an air electrode, is a porous layer of doped lanthanum manganite, the solid electrolyte layer (18) is a dense yttria stabilized zirconium oxide, the interconnect layer (16) is a dense, doped lanthanum chromite, and the second electrode (20), a fuel electrode, is a porous layer of nickel-zirconium oxide cermet. The electrochemical cell (10) can take on a plurality of shapes such as annular, planar, etc. and can be connected to a plurality of electrochemical cells in series and/or in parallel to generate electrical energy.

  12. High Summer Temperatures and Mortality in Estonia

    PubMed Central

    Oudin Åström, Daniel; Åström, Christofer; Rekker, Kaidi; Indermitte, Ene; Orru, Hans

    2016-01-01

    Background On-going climate change is predicted to result in a growing number of extreme weather events—such as heat waves—throughout Europe. The effect of high temperatures and heat waves are already having an important impact on public health in terms of increased mortality, but studies from an Estonian setting are almost entirely missing. We investigated mortality in relation to high summer temperatures and the time course of mortality in a coastal and inland region of Estonia. Methods We collected daily mortality data and daily maximum temperature for a coastal and an inland region of Estonia. We applied a distributed lag non-linear model to investigate heat related mortality and the time course of mortality in Estonia. Results We found an immediate increase in mortality associated with temperatures exceeding the 75th percentile of summer maximum temperatures, corresponding to approximately 23°C. This increase lasted for a couple of days in both regions. The total effect of elevated temperatures was not lessened by significant mortality displacement. Discussion We observed significantly increased mortality in Estonia, both on a country level as well as for a coastal region and an inland region with a more continental climate. Heat related mortality was higher in the inland region as compared to the coastal region, however, no statistically significant differences were observed. The lower risks in coastal areas could be due to lower maximum temperatures and cooling effects of the sea, but also better socioeconomic condition. Our results suggest that region specific estimates of the impacts of temperature extremes on mortality are needed. PMID:27167851

  13. Construction and Comparative Analyses of Highly Dense Linkage Maps of Two Sweet Cherry Intra-Specific Progenies of Commercial Cultivars

    PubMed Central

    Quero-García, José; Guzmán, Alejandra; Mansur, Levi; Gratacós, Eduardo; Silva, Herman; Rosyara, Umesh R.; Iezzoni, Amy; Meisel, Lee A.; Dirlewanger, Elisabeth

    2013-01-01

    Despite the agronomical importance and high synteny with other Prunus species, breeding improvements for cherry have been slow compared to other temperate fruits, such as apple or peach. However, the recent release of the peach genome v1.0 by the International Peach Genome Initiative and the sequencing of cherry accessions to identify Single Nucleotide Polymorphisms (SNPs) provide an excellent basis for the advancement of cherry genetic and genomic studies. The availability of dense genetic linkage maps in phenotyped segregating progenies would be a valuable tool for breeders and geneticists. Using two sweet cherry (Prunus avium L.) intra-specific progenies derived from crosses between ‘Black Tartarian’ × ‘Kordia’ (BT×K) and ‘Regina’ × ‘Lapins’(R×L), high-density genetic maps of the four parental lines and the two segregating populations were constructed. For BT×K and R×L, 89 and 121 F1 plants were used for linkage mapping, respectively. A total of 5,696 SNP markers were tested in each progeny. As a result of these analyses, 723 and 687 markers were mapped into eight linkage groups (LGs) in BT×K and R×L, respectively. The resulting maps spanned 752.9 and 639.9 cM with an average distance of 1.1 and 0.9 cM between adjacent markers in BT×K and R×L, respectively. The maps displayed high synteny and co-linearity between each other, with the Prunus bin map, and with the peach genome v1.0 for all eight LGs (LG1–LG8). These maps provide a useful tool for investigating traits of interest in sweet cherry and represent a qualitative advance in the understanding of the cherry genome and its synteny with other members of the Rosaceae family. PMID:23382953

  14. High-Temperature Adhesive Strain Gage Developed

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Roberts, Gary D.

    1997-01-01

    Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

  15. Two High-Temperature Foil Journal Bearings

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2006-01-01

    An enlarged, high-temperature-compliant foil bearing has been built and tested to demonstrate the feasibility of such bearings for use in aircraft gas turbine engines. Foil bearings are attractive for use in some machines in which (1) speeds of rotation, temperatures, or both exceed maximum allowable values for rolling-element bearings; (2) conventional lubricants decompose at high operating temperatures; and/or (3) it is necessary or desirable not to rely on conventional lubrication systems. In a foil bearing, the lubricant is the working fluid (e.g., air or a mixture of combustion gases) in the space between the journal and the shaft in the machine in which the bearing is installed.

  16. Gravimeter using high-temperature superconductor bearing.

    SciTech Connect

    Hull, J. R.

    1998-09-11

    We have developed a sensitive gravimeter concept that uses an extremely low-friction bearing based on a permanent magnet (PM) levitated over a high-temperature superconductor (HTS). A mass is attached to the PM by means of a cantilevered beam, and the combination of PM and HTS forms a bearing platform that has low resistance to rotational motion but high resistance to horizontal, vertical, or tilting motion. The combination acts as a low-loss torsional pendulum that can be operated in any orientation. Gravity acts on the cantilevered beam and attached mass, accelerating them. Variations in gravity can be detected by time-of-flight acceleration, or by a control coil or electrode that would keep the mass stationary. Calculations suggest that the HTS gravimeter would be as sensitive as present-day superconducting gravimeters that need cooling to liquid helium temperatures, but the HTS gravimeter needs cooling only to liquid nitrogen temperatures.

  17. High Temperature Materials Interim Data Qualification Report

    SciTech Connect

    Nancy Lybeck

    2010-08-01

    ABSTRACT Projects for the very high temperature reactor (VHTR) Technology Development Office provide data in support of Nuclear Regulatory Commission licensing of the VHTR. Fuel and materials to be used in the reactor are tested and characterized to quantify performance in high temperature and high fluence environments. The VHTR program has established the NGNP Data Management and Analysis System (NDMAS) to ensure that VHTR data are qualified for use, stored in a readily accessible electronic form, and analyzed to extract useful results. This document focuses on the first NDMAS objective. It describes the High Temperature Materials characterization data stream, the processing of these data within NDMAS, and reports the interim FY2010 qualification status of the data. Data qualification activities within NDMAS for specific types of data are determined by the data qualification category assigned by the data generator. The High Temperature Materials data are being collected under NQA-1 guidelines, and will be qualified data. For NQA-1 qualified data, the qualification activities include: (1) capture testing, to confirm that the data stored within NDMAS are identical to the raw data supplied, (2) accuracy testing to confirm that the data are an accurate representation of the system or object being measured, and (3) documenting that the data were collected under an NQA-1 or equivalent Quality Assurance program. Currently, data from two test series within the High Temperature Materials data stream have been entered into the NDMAS vault: 1. Tensile Tests for Sm (i.e., Allowable Stress) Confirmatory Testing – 1,403,994 records have been inserted into the NDMAS database. Capture testing is in process. 2. Creep-Fatigue Testing to Support Determination of Creep-Fatigue Interaction Diagram – 918,854 records have been processed and inserted into the NDMAS database. Capture testing is in process.

  18. A nutrient-dense, high fiber, fruit-based supplement bar increases HDL, particularly large HDL, lowers homocysteine, and raises glutathione in a 2-week trial

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dietary intake modulates disease risk, but little is known as to how components within food mixtures affect pathophysiology. Here, a low-calorie, high-fiber, fruit-based nutrient-dense bar of defined composition (e.g., vitamins/minerals, fruit polyphenolics, B-glucan, docosahexaenoic acid (DHA)) app...

  19. High pressure and high temperature behaviour of ZnO

    SciTech Connect

    Thakar, Nilesh A.; Bhatt, Apoorva D.; Pandya, Tushar C.

    2014-04-24

    The thermodynamic properties with the wurtzite (B4) and rocksalt (B1) phases of ZnO under high pressures and high temperatures have been investigated using Tait's Equation of state (EOS). The effects of pressures and temperatures on thermodynamic properties such as bulk modulus, thermal expansivity and thermal pressure are explored for both two structures. It is found that ZnO material gradually softens with increase of temperature while it hardens with the increment of the pressure. Our predicted results of thermodynamics properties for both the phases of ZnO are in overall agreement with the available data in the literature.

  20. Enamel for high-temperature superalloys

    NASA Technical Reports Server (NTRS)

    Levin, H.; Lent, W. E.

    1977-01-01

    Desired optical and high temperature enamel properties are obtained with glasses prepared from the system Li2O-ZrO2-nSiO2. Molar compositions range from n=4 to n=1.3, to which are added minor amounts in varying combinations of alumina, alkali fluorides, boric oxide, alkali oxides, and akaline earth oxides.

  1. 10.3 High-temperature Instrumentation

    NASA Technical Reports Server (NTRS)

    Piazza, Anthony

    2008-01-01

    This viewgraph presentation describes high temperature instrumentation development from 1960-1970, 1980-1990 and 2000-present. The contents include: 1) Background; 2) Objective; 3) Application and Sensor; 4) Attachment Techniques; 5) Evaluation/Characterization Testing; and 6) Future testing.

  2. Progress in advanced high temperature materials technology

    NASA Technical Reports Server (NTRS)

    Freche, J. C.; Ault, G. M.

    1976-01-01

    Significant progress has recently been made in many high temperature material categories pertinent to such applications by the industrial community. These include metal matrix composites, superalloys, directionally solidified eutectics, coatings, and ceramics. Each of these material categories is reviewed and the current state-of-the-art identified, including some assessment, when appropriate, of progress, problems, and future directions.

  3. High temperature pressure coupled ultrasonic waveguide

    DOEpatents

    Caines, Michael J.

    1983-01-01

    A pressure coupled ultrasonic waveguide is provided to which one end may be attached a transducer and at the other end a high temperature material for continuous ultrasonic testing of the material. The ultrasonic signal is coupled from the waveguide into the material through a thin, dry copper foil.

  4. Lightweight High-Temperature Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Wagner, W. R.; Fasheh, J. I.

    1985-01-01

    Fine Ni/Cr fibers sintered into corrosion-resistant, fireproof batt. Possible applications include stoves, furnaces, safes, fire clothing, draperies in public buildings, wall firebreaks, airplane walls, and jetengine components. New insulation takes advantage of some of same properties of nickel/chromium alloy useful in heating elements in toasters, namely, corrosion and oxidation resistance even at high temperatures.

  5. Space applications of high temperature superconductivity technology

    NASA Technical Reports Server (NTRS)

    Connolly, D. J.; Aron, P. R.; Leonard, R. F.; Wintucky, E. G.

    1991-01-01

    A review is presented of the present status of high temperature superconductivity (HTS) technology and related areas of potential space application. Attention is given to areas of application that include microwave communications, cryogenic systems, remote sensing, and space propulsion and power. Consideration is given to HTS phase shifters, miniaturization of microwave filters, far-IR bolometers, and magnetic refrigeration using flux compression.

  6. Improved high-temperature silicide coatings

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.; Stephens, J. R.; Stetson, A. R.; Wimber, R. T.

    1969-01-01

    Special technique for applying silicide coatings to refractory metal alloys improves their high-temperature protective capability. Refractory metal powders mixed with a baked-out organic binder and sintered in a vacuum produces a porous alloy layer on the surface. Exposing the layer to hot silicon converts it to a silicide.

  7. High-temperature corrosion in halogen environments

    SciTech Connect

    McNallan, M. )

    1994-09-01

    Halogen contaminants, particularly chlorine and fluorine, cause accelerated corrosion in such high-temperature systems as waste incinerators and waste heat recuperators on metallurgical furnaces. The mechanisms by which these phenomena occur are reviewed and discussed with the goal of identifying appropriate corrosion control strategies for materials that operate in these environments.

  8. High temperature oxidation resistant cermet compositions

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (Inventor)

    1976-01-01

    Cermet compositions are designed to provide high temperature resistant refractory coatings on stainless steel or molybdenum substrates. A ceramic mixture of chromium oxide and aluminum oxide form a coating of chromium oxide as an oxidation barrier around the metal particles, to provide oxidation resistance for the metal particles.

  9. High Temperature Langasite SAW Oxygen Sensor

    SciTech Connect

    Zheng, Peng; Chin, Tao-Lun; Greve, David; Oppenheim, Irving; Malone, Vanessa; Cao, Limin

    2011-08-01

    High-temperature langasite SAW oxygen sensors using sputtered ZnO as a resistive gas-sensing layer were fabricated and tested. Sensitivity to oxygen gas was observed between 500°C to 700°C, with a sensitivity peak at about 625°C, consistent with the theoretical predictions of the acoustoelectric effect.

  10. High temperature well bore cement slurry

    SciTech Connect

    Nahm, J.J.W.; Vinegar, H.J.; Karanikas, J.M.; Wyant, R.E.

    1993-07-13

    A low density well bore cement slurry composition is described suitable for cementing well bores with high reservoir temperatures comprising: (a) a high alumina cement in an amount of about 40 pounds per barrel of slurry or greater: (b) graphite in an amount greater than about one quarter, by volume, of the solids in the cement slurry; and (c) and a carrier fluid comprising drilling mud.

  11. Ultra high temperature ceramics for hypersonic vehicle applications.

    SciTech Connect

    Tandon, Rajan; Dumm, Hans Peter; Corral, Erica L.; Loehman, Ronald E.; Kotula, Paul Gabriel

    2006-01-01

    HfB{sub 2} and ZrB{sub 2} are of interest for thermal protection materials because of favorable thermal stability, mechanical properties, and oxidation resistance. We have made dense diboride ceramics with 2 to 20 % SiC by hot pressing at 2000 C and 5000 psi. High-resolution transmission electron microscopy (TEM) shows very thin grain boundary phases that suggest liquid phase sintering. Fracture toughness measurements give RT values of 4 to 6 MPam{sup 1/2}. Four-pt flexure strengths measured in air up to 1450 C were as high as 450-500 MPa. Thermal diffusivities were measured to 2000 C for ZrB{sub 2} and HfB{sub 2} ceramics with SiC contents from 2 to 20%. Thermal conductivities were calculated from thermal diffusivities and measured heat capacities. Thermal diffusivities were modeled using different two-phase composite models. These materials exhibit excellent high temperature properties and are attractive for further development for thermal protection systems.

  12. Urania vapor composition at very high temperatures

    SciTech Connect

    Pflieger, Rachel; Colle, Jean-Yves; Iosilevskiy, Igor; Sheindlin, Michael

    2011-02-01

    Due to the chemically unstable nature of uranium dioxide its vapor composition at very high temperatures is, presently, not sufficiently studied though more experimental knowledge is needed for risk assessment of nuclear reactors. We used laser vaporization coupled to mass spectrometry of the produced vapor to study urania vapor composition at temperatures in the vicinity of its melting point and higher. The very good agreement between measured melting and freezing temperatures and between partial pressures measured on the temperature increase and decrease indicated that the change in stoichiometry during laser heating was very limited. The evolutions with temperature (in the range 2800-3400 K) of the partial pressures of the main vapor species (UO{sub 2}, UO{sub 3}, and UO{sub 2}{sup +}) were compared with theoretically predicted evolutions for equilibrium noncongruent gas-liquid and gas-solid phase coexistences and showed very good agreement. The measured main relative partial pressure ratios around 3300 K all agree with calculated values for total equilibrium between condensed and vapor phases. It is the first time the three main partial pressure ratios above stoichiometric liquid urania have been measured at the same temperature under conditions close to equilibrium noncongruent gas-liquid phase coexistence.

  13. High temperature annealing of ion irradiated tungsten

    SciTech Connect

    Ferroni, Francesco; Yi, Xiaoou; Fitzgerald, Steven P.; Edmondson, Philip D.; Roberts, Steve G.

    2015-03-21

    In this study, transmission electron microscopy of high temperature annealing of pure tungsten irradiated by self-ions was conducted to elucidate microstructural and defect evolution in temperature ranges relevant to fusion reactor applications (500–1200°C). Bulk isochronal and isothermal annealing of ion irradiated pure tungsten (2 MeV W+ ions, 500°C, 1014 W+/cm2) with temperatures of 800, 950, 1100 and 1400°C, from 0.5 to 8 h, was followed by ex situ characterization of defect size, number density, Burgers vector and nature. Loops with diameters larger than 2–3 nm were considered for detailed analysis, among which all loops had View the MathML source and were predominantly of interstitial nature. In situ annealing experiments from 300 up to 1200°C were also carried out, including dynamic temperature ramp-ups. These confirmed an acceleration of loop loss above 900°C. At different temperatures within this range, dislocations exhibited behaviour such as initial isolated loop hopping followed by large-scale rearrangements into loop chains, coalescence and finally line–loop interactions and widespread absorption by free-surfaces at increasing temperatures. An activation energy for the annealing of dislocation length was obtained, finding Ea=1.34±0.2 eV for the 700–1100°C range.

  14. High temperature annealing of ion irradiated tungsten

    DOE PAGES

    Ferroni, Francesco; Yi, Xiaoou; Arakawa, Kazuto; Fitzgerald, Steven P.; Edmondson, Philip D.; Roberts, Steve G.

    2015-03-21

    In this study, transmission electron microscopy of high temperature annealing of pure tungsten irradiated by self-ions was conducted to elucidate microstructural and defect evolution in temperature ranges relevant to fusion reactor applications (500–1200°C). Bulk isochronal and isothermal annealing of ion irradiated pure tungsten (2 MeV W+ ions, 500°C, 1014 W+/cm2) with temperatures of 800, 950, 1100 and 1400°C, from 0.5 to 8 h, was followed by ex situ characterization of defect size, number density, Burgers vector and nature. Loops with diameters larger than 2–3 nm were considered for detailed analysis, among which all loops had View the MathML source andmore » were predominantly of interstitial nature. In situ annealing experiments from 300 up to 1200°C were also carried out, including dynamic temperature ramp-ups. These confirmed an acceleration of loop loss above 900°C. At different temperatures within this range, dislocations exhibited behaviour such as initial isolated loop hopping followed by large-scale rearrangements into loop chains, coalescence and finally line–loop interactions and widespread absorption by free-surfaces at increasing temperatures. An activation energy for the annealing of dislocation length was obtained, finding Ea=1.34±0.2 eV for the 700–1100°C range.« less

  15. High temperature furnace modeling and performance verifications

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.

    1992-01-01

    Analytical, numerical, and experimental studies were performed on two classes of high temperature materials processing sources for their potential use as directional solidification furnaces. The research concentrated on a commercially available high temperature furnace using a zirconia ceramic tube as the heating element and an Arc Furnace based on a tube welder. The first objective was to assemble the zirconia furnace and construct parts needed to successfully perform experiments. The 2nd objective was to evaluate the zirconia furnace performance as a directional solidification furnace element. The 3rd objective was to establish a data base on materials used in the furnace construction, with particular emphasis on emissivities, transmissivities, and absorptivities as functions of wavelength and temperature. A 1-D and 2-D spectral radiation heat transfer model was developed for comparison with standard modeling techniques, and were used to predict wall and crucible temperatures. The 4th objective addressed the development of a SINDA model for the Arc Furnace and was used to design sample holders and to estimate cooling media temperatures for the steady state operation of the furnace. And, the 5th objective addressed the initial performance evaluation of the Arc Furnace and associated equipment for directional solidification. Results of these objectives are presented.

  16. High temperature intermetallic binders for HVOF carbides

    SciTech Connect

    Shaw, K.G.; Gruninger, M.F.; Jarosinski, W.J.

    1994-12-31

    Gas turbines technology has a long history of employing the desirable high temperature physical attributes of ceramic-metallic (cermet) materials. The most commonly used coatings incorporate combinations of WC-Co and Cr{sub 3}C{sub 2}-NiCr, which have also been successfully utilized in other non-turbine coating applications. Increased turbine operating temperatures and other high temperature service conditions have made apparent the attractive notion of increasing the temperature capability and corrosion resistance of these coatings. In this study the intermetallic binder NiAl has been used to replace the cobalt and NiCr constituents of conventional WC and Cr{sub 3}C{sub 2} cermet powders. The composite carbide thermal spray powders were fabricated for use in the HVOF coating process. The structure of HVOF deposited NiAl-carbide coatings are compared directly to the more familiar WC-Co and Cr{sub 3}C{sub 2}-NiCr coatings using X-ray diffraction, back-scattered electron imaging (BEI) and electron dispersive spectroscopy (EDS). Hardness variations with temperature are reported and compared between the NiAl and Co/NiCr binders.

  17. Advanced high temperature thermoelectrics for space power

    NASA Technical Reports Server (NTRS)

    Lockwood, A.; Ewell, R.; Wood, C.

    1981-01-01

    Preliminary results from a spacecraft system study show that an optimum hot junction temperature is in the range of 1500 K for advanced nuclear reactor technology combined with thermoelectric conversion. Advanced silicon germanium thermoelectric conversion is feasible if hot junction temperatures can be raised roughly 100 C or if gallium phosphide can be used to improve the figure of merit, but the performance is marginal. Two new classes of refractory materials, rare earth sulfides and boron-carbon alloys, are being investigated to improve the specific weight of the generator system. Preliminary data on the sulfides have shown very high figures of merit over short temperature ranges. Both n- and p-type doping have been obtained. Pure boron-carbide may extrapolate to high figure of merit at temperatures well above 1500 K but not lower temperature; n-type conduction has been reported by others, but not yet observed in the JPL program. Inadvertant impurity doping may explain the divergence of results reported.

  18. High temperature superconductors applications in telecommunications

    NASA Technical Reports Server (NTRS)

    Kumar, A. Anil; Li, Jiang; Zhang, Ming Fang

    1995-01-01

    The purpose of this paper is twofold: (1) to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and (2) to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices - obvious advantages versus practical difficulties - needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models - a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B) - shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance - conductivity, surface resistance and attenuation constant - will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T

  19. High temperature superconductors applications in telecommunications

    SciTech Connect

    Kumar, A.A.; Li, J.; Zhang, M.F.

    1994-12-31

    The purpose of this paper is twofold: to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices-obvious advantages versus practical difficulties-needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models-a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B)-shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance-conductivity, surface resistance and attenuation constant-will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T{sub c} superconductors.

  20. Age and hormonal status as determinants of cataractogenesis induced by ionizing radiation. I. Densely ionizing (high-LET) radiation.

    PubMed

    Dynlacht, Joseph R; Valluri, Shailaja; Garrett, Joy; Mendonca, Marc S; Lopez, Jennifer T; Caperell-Grant, Andrea; Bigsby, Robert M

    2011-01-01

    Astronauts participating in extended lunar missions or the projected mission to Mars would likely be exposed to significant doses of high-linear energy transfer (LET) heavy energetic charged (HZE) particles. Exposure to even relatively low doses of such space radiation may result in a reduced latent period for and an increased incidence of lens opacification. However, the determinants of cataractogenesis induced by densely ionizing radiation have not been clearly elucidated. In the current study, we show that age at the time of exposure is a key determinant of cataractogenesis in rats whose eyes have been exposed to 2 Gy of (56)Fe ions. The rate of progression of cataractogenesis was significantly greater in the irradiated eyes of 1-year-old rats compared to young (56-day-old) rats. Furthermore, older ovariectomized rats that received exogenous estrogen treatment (17-β-estradiol) commencing 1 week prior to irradiation and continuing throughout the period of observation of up to approximately 600 days after irradiation showed an increased incidence of cataracts and faster progression of opacification compared to intact rats with endogenous estrogen or ovariectomized rats. The same potentiating effect (higher incidence, reduced latent period) was observed for irradiated eyes of young rats. Modulation of estrogen status in the 1-year-old animals (e.g., removal of estrogen by ovariectomy or continuous exposure to estrogen) did not increase the latent period or reduce the incidence to that of intact 56-day-old rats. Since the rapid onset and progression of cataracts in 1-year-old compared to 56-day-old rats was independent of estrogen status, we conclude that estrogen cannot account for the age-dependent differences in cataractogenesis induced by high-LET radiation. PMID:21175345

  1. Operator manual: High temperature heat pump

    NASA Astrophysics Data System (ADS)

    Dyer, D. F.; Maples, G.; Burch, T. E.; Chancellor, P. D.

    1980-03-01

    Experimental data were obtained from operating a high temperature heat pump system. The use of methanol as a working fluid necessitated careful monitoring of refrigerant temperatures and pressures with chemical analysis performed on the working fluid during scheduled down time. Materials sent to vendors and quotes received concerning equipment (compressor, evaporator, condensor, air heater, dryer, two accumulator tanks, and three expansion valves) are discussed. The detailed design and pricing estimates are included. Additional information on layout and construction; start-up; testing; shut down; scheduled maintenance and inspection; safety precautions; control system; and trouble shooting is presented.

  2. Coal transformation under high-temperature catagenesis

    SciTech Connect

    Melenevsky, V.N.; Sokol, E.V.; Fomin, A.N.

    2006-07-01

    In this paper we consider products of natural pyrolysis of lignite, which resulted from the high-temperature spontaneous combustion of spoil heaps of the Chelyabinsk coal basin. These products were studied by pyrolysis, element and petrographic analyses, chromatomass spectrometry, and X-ray diffraction method. We have established that under reducing conditions, the degree of pyrogenic coal transformation and the composition of pyrolysis products vary greatly, from graphite-like phases to bitumens, and depend on the temperature and degree of the system openness.

  3. Fiber specklegram sensors sensitivities at high temperatures

    NASA Astrophysics Data System (ADS)

    Rodriguez-Cobo, L.; Lomer, M.; Lopez-Higuera, J. M.

    2015-09-01

    In this work, the sensitivity of Fiber Specklegram Sensors to high temperatures (up to 800ºC) have been studied. Two multimode silica fibers have been introduced into a tubular furnace while a HeNe laser source was launched into a fiber edge, projecting speckle patterns to a commercial webcam. A computer generated different heating and cooling sweeps while the specklegram evolution was recorded. The achieved results exhibit a remarkably linearity in FSS's sensitivity for temperatures under 800ºC, following the thermal expansion of fused silica.

  4. High-Temperature Behavior of Cellulose I

    SciTech Connect

    Matthews, James F.; Bergenstråhle, Malin; Beckham, Gregg T.; Himmel, Michael E.; Nimlos, Mark R.; Brady, John W.; Crowley, Michael F.

    2011-03-17

    We use molecular simulation to elucidate the structural behavior of small hydrated cellulose Iβ microfibrils heated to 227 °C (500 K) with two carbohydrate force fields. In contrast to the characteristic two-dimensional hydrogen-bonded layer sheets present in the cellulose Iβ crystal structure, we show that at high temperature a three-dimensional hydrogen bond network forms, made possible by hydroxymethyl groups changing conformation from trans–gauche (TG) to gauche–gauche (GG) in every second layer corresponding to “center” chains in cellulose Iβ and from TG to gauche–trans (GT) in the “origin” layer. The presence of a regular three-dimensional hydrogen bond network between neighboring sheets eliminates the possibility of twist, whereas two-dimensional hydrogen bonding allows for microfibril twist to occur. Structural features of this high-temperature phase as determined by molecular simulation may explain several experimental observations for which no detailed structural basis has been offered. This includes an explanation for the observed temperature and crystal size dependence for the extent of hydrogen/deuterium exchange, and diffraction patterns of cellulose at high temperature.

  5. The moon as a high temperature condensate

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1972-01-01

    The accretion during condensation mechanism is used to explain the differences in composition of the terrestrial planets and the moon. Many of the properties of the moon, including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the depletion in Fe, Rb, K, Na and other volatiles can be understood if the moon represents a high temperature condensate from the solar nebula. Thermodynamic calculations show that Ca, Al and Ti rich compounds condense first in a cooling nebula. The high temperature mineralogy is gehlenite, spinel perovskite, Ca-Al-rich pyroxenes and anorthite. The model is consistent with extensive early melting, shallow melting at 3 A.E. and with presently high speed internal temperatures. It is predicted that the outer 250 km is rich in plagioclase and FeO. The low iron content of the interior in this model raises the interior temperatures estimated from electrical conductivity by some 800 C. The lunar crust is 80 percent gabbroic anorthosite, 20 percent basalt and is about 250-270 km thick. The lunar mantle is probably composed of spinel, merwinite and diopside with a density of 3.4 g/cu cm.

  6. High temperature dynamic engine seal technology development

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M.; Dellacorte, Christopher; Machinchick, Michael; Mutharasan, Rajakkannu; Du, Guang-Wu; Ko, Frank; Sirocky, Paul J.; Miller, Jeffrey H.

    1992-01-01

    Combined cycle ramjet/scramjet engines being designed for advanced hypersonic vehicles, including the National Aerospace Plane (NASP), require innovative high temperature dynamic seals to seal the sliding interfaces of the articulated engine panels. New seals are required that will operate hot (1200 to 2000 F), seal pressures ranging from 0 to 100 psi, remain flexible to accommodate significant sidewall distortions, and resist abrasion over the engine's operational life. This report reviews the recent high temperature durability screening assessments of a new braided rope seal concept, braided of emerging high temperature materials, that shows promise of meeting many of the seal demands of hypersonic engines. The paper presents durability data for: (1) the fundamental seal building blocks, a range of candidate ceramic fiber tows; and for (2) braided rope seal subelements scrubbed under engine simulated sliding, temperature, and preload conditions. Seal material/architecture attributes and limitations are identified through the investigations performed. The paper summarizes the current seal technology development status and presents areas in which future work will be performed.

  7. Lightweight high-temperature fuel metering valves

    NASA Astrophysics Data System (ADS)

    Bennett, Joe

    AlliedSignal Fluid systems has provided fuel metering valve hardware to three aircraft engine manufacturers for evaluation. Two of the progams were Integrated High Performance Turbine Engine Technology (IHPTET) related. The third program was an IR&D effort. Bench tests and evaluation of all three valve designs have been completed, and one of the designs has actually been used for engine test. Engine testing of the other two valve designs is planned for the future. These three designs are similar, but each is intended to be usused in different system configurations, and each valve design offers unique features. The design approaches used for the three valve designs incorporate several new and innovative technologies, including high-temperature brushless dc motor actuators, low-pressure loss metering element design, fiber optic rotarty output position sensor, no-moving-parts oscillating jet flow meter, high-temperature RS (rapid solidification) aluminum alloy, high-temperature elastomeric seals, high-pressure shutoff capabilities, and closed loop electronic fuel flow metering.

  8. High temperature aircraft research furnace facilities

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.; Cashon, John L.

    1992-01-01

    Focus is on the design, fabrication, and development of the High Temperature Aircraft Research Furnace Facilities (HTARFF). The HTARFF was developed to process electrically conductive materials with high melting points in a low gravity environment. The basic principle of operation is to accurately translate a high temperature arc-plasma gas front as it orbits around a cylindrical sample, thereby making it possible to precisely traverse the entire surface of a sample. The furnace utilizes the gas-tungsten-arc-welding (GTAW) process, also commonly referred to as Tungsten-Inert-Gas (TIG). The HTARFF was developed to further research efforts in the areas of directional solidification, float-zone processing, welding in a low-gravity environment, and segregation effects in metals. The furnace is intended for use aboard the NASA-JSC Reduced Gravity Program KC-135A Aircraft.

  9. High-Temperature Graphite/Phenolic Composite

    NASA Technical Reports Server (NTRS)

    Seal, Ellis C.; Bodepudi, Venu P.; Biggs, Robert W., Jr.; Cranston, John A.

    1995-01-01

    Graphite-fiber/phenolic-resin composite material retains relatively high strength and modulus of elasticity at temperatures as high as 1,000 degrees F. Costs only 5 to 20 percent as much as refractory materials. Fabrication composite includes curing process in which application of full autoclave pressure delayed until after phenolic resin gels. Curing process allows moisture to escape, so when composite subsequently heated in service, much less expansion of absorbed moisture and much less tendency toward delamination. Developed for nose cone of external fuel tank of Space Shuttle. Other potential aerospace applications for material include leading edges, parts of nozzles, parts of aircraft engines, and heat shields. Terrestrial and aerospace applications include structural firewalls and secondary structures in aircraft, spacecraft, and ships. Modified curing process adapted to composites of phenolic with other fiber reinforcements like glass or quartz. Useful as high-temperature circuit boards and electrical insulators.

  10. The metallurgy of high temperature alloys

    NASA Technical Reports Server (NTRS)

    Tien, J. K.; Purushothaman, S.

    1976-01-01

    Nickel-base, cobalt-base, and high nickel and chromium iron-base alloys are dissected, and their microstructural and chemical components are assessed with respect to the various functions expected of high temperature structural materials. These functions include the maintenance of mechanical integrity over the strain-rate spectrum from creep resistance through fatigue crack growth resistance, and such alloy stability expectations as microstructural coarsening resistance, phase instability resistance and oxidation and corrosion resistance. Special attention will be given to the perennial conflict and trade-off between strength, ductility and corrosion and oxidation resistance. The newest developments in the constitution of high temperature alloys will also be discussed, including aspects relating to materials conservation.

  11. Optically transparent high temperature shape memory polymers.

    PubMed

    Xiao, Xinli; Qiu, Xueying; Kong, Deyan; Zhang, Wenbo; Liu, Yanju; Leng, Jinsong

    2016-03-21

    Optically transparent shape memory polymers (SMPs) have potential in advanced optoelectronic and other common shape memory applications, and here optically transparent shape memory polyimide is reported for the first time. The polyimide possesses a glass transition temperature (Tg) of 171 °C, higher than the Tg of other transparent SMPs reported, and the influence of molecular structure on Tg is discussed. The 120 μm thick polyimide film exhibits transmittance higher than 81% in 450-800 nm, and the possible mechanism of its high transparency is analyzed, which will benefit further research on other transparent high temperature SMPs. The transparent polyimide showed excellent thermomechanical properties and shape memory performances, and retained high optical transparency after many shape memory cycles. PMID:26686222

  12. High Temperature Fluoride Salt Test Loop

    SciTech Connect

    Aaron, Adam M.; Cunningham, Richard Burns; Fugate, David L.; Holcomb, David Eugene; Kisner, Roger A.; Peretz, Fred J.; Robb, Kevin R.; Wilson, Dane F.; Yoder, Jr, Graydon L.

    2015-12-01

    Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, good heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels

  13. Manufacture of dense sintered bodies containing silicon nitride

    NASA Technical Reports Server (NTRS)

    Hirota, K.; Hasegawa, Y.; Ogura, K.; Yashima, Y.

    1985-01-01

    Sintered bodies containing 1-32.5 Si oxide and 1.5 wt.% SiC (Si oxide/SiC wt. ratio 3/2) are prepared and kept in a 10-3000 kg/2 sq. cm. N (g) atmosphere at 1500-2300 degrees, while simultaneously maintaining the CO (g) partial pressure around the body lower than the nitrogenation equil. pressure to give a dense sintered body. The prepared dense sintered body has high strength at high temperatures. Thus, SiC 40, oxide 30 and Si3N4 30 wt% were fired to a body which was kept in 1500 kg/sq. cm. N (g) for 20 h at 2000 degrees to give a dense sintered body having high bending strength at high temperatures.

  14. Gasification of high ash, high ash fusion temperature bituminous coals

    DOEpatents

    Liu, Guohai; Vimalchand, Pannalal; Peng, WanWang

    2015-11-13

    This invention relates to gasification of high ash bituminous coals that have high ash fusion temperatures. The ash content can be in 15 to 45 weight percent range and ash fusion temperatures can be in 1150.degree. C. to 1500.degree. C. range as well as in excess of 1500.degree. C. In a preferred embodiment, such coals are dealt with a two stage gasification process--a relatively low temperature primary gasification step in a circulating fluidized bed transport gasifier followed by a high temperature partial oxidation step of residual char carbon and small quantities of tar. The system to process such coals further includes an internally circulating fluidized bed to effectively cool the high temperature syngas with the aid of an inert media and without the syngas contacting the heat transfer surfaces. A cyclone downstream of the syngas cooler, operating at relatively low temperatures, effectively reduces loading to a dust filtration unit. Nearly dust- and tar-free syngas for chemicals production or power generation and with over 90%, and preferably over about 98%, overall carbon conversion can be achieved with the preferred process, apparatus and methods outlined in this invention.

  15. ATCA survey of ammonia in the galactic center: The temperatures of dense gas clumps between Sgr A* and Sgr B2

    SciTech Connect

    Ott, Jürgen; Weiß, Axel; Henkel, Christian; Staveley-Smith, Lister; Meier, David S. E-mail: aweiss@mpifr-bonn.mpg.de E-mail: Lister.Staveley-Smith@uwa.edu.au

    2014-04-10

    We present a large-scale, interferometric survey of ammonia (1, 1) and (2, 2) toward the Galactic center observed with the Australia Telescope Compact Array. The survey covers Δℓ ∼ 1° (∼150 pc at an assumed distance of 8.5 kpc) and Δb ∼ 0.°2 (∼30 pc) which spans the region between the supermassive black hole Sgr A* and the massive star forming region Sgr B2. The resolution is ∼20'' (∼0.8 pc) and emission at scales ≳ 2' (≳ 3.2 pc) is filtered out due to missing interferometric short spacings. Consequently, the data represent the denser, compact clouds and disregards the large-scale, diffuse gas. Many of the clumps align with the 100 pc dust ring and mostly anti-correlate with 1.2 cm continuum emission. We present a kinetic temperature map of the dense gas. The temperature distribution peaks at ∼38 K with a width at half maximum between 18 K and 61 K (measurements sensitive within T {sub kin} ∼ 10-80 K). Larger clumps are on average warmer than smaller clumps which suggests internal heating sources. Our observations indicate that the circumnuclear disk ∼1.5 pc around Sgr A* is supplied with gas from the 20 km s{sup –1} molecular cloud. This gas is substantially cooler than gas ∼3-15 pc away from Sgr A*. We find a strong temperature gradient across Sgr B2. Ammonia column densities correlate well with SCUBA 850 μm fluxes, but the relation is shifted from the origin, which may indicate a requirement for a minimum amount of dust to form and shield ammonia. Around the Arches and Quintuplet clusters we find shell morphologies with UV-influenced gas in their centers, followed by ammonia and radio continuum layers.

  16. ATCA Survey of Ammonia in the Galactic Center: The Temperatures of Dense Gas Clumps between Sgr A* and Sgr B2

    NASA Astrophysics Data System (ADS)

    Ott, Jürgen; Weiß, Axel; Staveley-Smith, Lister; Henkel, Christian; Meier, David S.

    2014-04-01

    We present a large-scale, interferometric survey of ammonia (1, 1) and (2, 2) toward the Galactic center observed with the Australia Telescope Compact Array. The survey covers Δl ~ 1° (~150 pc at an assumed distance of 8.5 kpc) and Δb ~ 0.°2 (~30 pc) which spans the region between the supermassive black hole Sgr A* and the massive star forming region Sgr B2. The resolution is ~20'' (~0.8 pc) and emission at scales >~ 2' (gsim 3.2 pc) is filtered out due to missing interferometric short spacings. Consequently, the data represent the denser, compact clouds and disregards the large-scale, diffuse gas. Many of the clumps align with the 100 pc dust ring and mostly anti-correlate with 1.2 cm continuum emission. We present a kinetic temperature map of the dense gas. The temperature distribution peaks at ~38 K with a width at half maximum between 18 K and 61 K (measurements sensitive within T kin ~ 10-80 K). Larger clumps are on average warmer than smaller clumps which suggests internal heating sources. Our observations indicate that the circumnuclear disk ~1.5 pc around Sgr A* is supplied with gas from the 20 km s-1 molecular cloud. This gas is substantially cooler than gas ~3-15 pc away from Sgr A*. We find a strong temperature gradient across Sgr B2. Ammonia column densities correlate well with SCUBA 850 μm fluxes, but the relation is shifted from the origin, which may indicate a requirement for a minimum amount of dust to form and shield ammonia. Around the Arches and Quintuplet clusters we find shell morphologies with UV-influenced gas in their centers, followed by ammonia and radio continuum layers.

  17. Strain sensing technology for high temperature applications

    NASA Technical Reports Server (NTRS)

    Williams, W. Dan

    1993-01-01

    This review discusses the status of strain sensing technology for high temperature applications. Technologies covered are those supported by NASA such as required for applications in hypersonic vehicles and engines, advanced subsonic engines, as well as material and structure development. The applications may be at temperatures of 540 C (1000 F) to temperatures in excess of 1400 C (2500 F). The most promising technologies at present are the resistance strain gage and remote sensing schemes. Resistance strain gages discussed include the BCL gage, the LaRC compensated gage, and the PdCr gage. Remote sensing schemes such as laser based speckle strain measurement, phase-shifling interferometry, and x-ray extensometry are discussed. Present status and limitations of these technologies are presented.

  18. Improved high-temperature resistant matrix resins

    NASA Technical Reports Server (NTRS)

    Green, H. E.; Chang, G. E.; Wright, W. F.; Ueda, K.; Orell, M. K.

    1989-01-01

    A study was performed with the objective of developing matrix resins that exhibit improved thermo-oxidative stability over state-of-the-art high temperature resins for use at temperatures up to 644 K (700 F) and air pressures up to 0.7 MPa (100 psia). The work was based upon a TRW discovered family of polyimides currently licensed to and marketed by Ethyl Corporation as EYMYD(R) resins. The approach investigated to provide improved thermo-oxidative properties was to use halogenated derivatives of the diamine, 2, 2-bis (4-(4-aminophenoxy)phenyl) hexafluoropropane (4-BDAF). Polyimide neat resins and Celion(R) 12,000 composites prepared from fluorine substituted 4-BDAF demonstrated unexpectedly lower glass transition temperatures (Tg) and thermo-oxidative stabilities than the baseline 4-BDAF/PMDA polymer.

  19. Compliant high temperature seals for dissimilar materials

    DOEpatents

    Rynders, Steven Walton; Minford, Eric; Tressler, Richard Ernest; Taylor, Dale M.

    2001-01-01

    A high temperature, gas-tight seal is formed by utilizing one or more compliant metallic toroidal ring sealing elements, where the applied pressure serves to activate the seal, thus improving the quality of the seal. The compliant nature of the sealing element compensates for differences in thermal expansion between the materials to be sealed, and is particularly useful in sealing a metallic member and a ceramic tube art elevated temperatures. The performance of the seal may be improved by coating the sealing element with a soft or flowable coating such as silver or gold and/or by backing the sealing element with a bed of fine powder. The material of the sealing element is chosen such that the element responds to stress elastically, even at elevated temperatures, permitting the seal to operate through multiple thermal cycles.

  20. Thermoelectric properties by high temperature annealing

    NASA Technical Reports Server (NTRS)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Kumar, Shankar (Inventor); Lee, Hohyun (Inventor)

    2009-01-01

    The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

  1. Opacification of high temperature fibrous insulation

    NASA Technical Reports Server (NTRS)

    Miller, W. C.; Collins, J. O.

    1984-01-01

    A study was conducted to determine the merits of adding particulate materials to silica fiber felts to increase their resistance to the passage of thermal radiation. Laboratory samples containing 5, 10, and 15 percent of chromium oxide, silicon carbide, and titanium dioxide were prepared and evaluated in accordance with ASTM C-518 thermal conductivity test method at 425 C (800 F) mean temperature. The titania particles averaging 3-4 micrometers in diameter were found to be the most effective. This was followed by a short plant run, in order to confirm the initial results on the laboratory samples. These samples were tested according to ASTM C-201 High Temperature Calorimeter from 93 C to 760 C (200 F to 1400 F) mean temperature. The ten percent by weight of titania resulted in an optimum effectiveness, and reduced the conductivity over 20% at 760 C (1400 F).

  2. Simulated Data for High Temperature Composite Design

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Abumeri, Galib H.

    2006-01-01

    The paper describes an effective formal method that can be used to simulate design properties for composites that is inclusive of all the effects that influence those properties. This effective simulation method is integrated computer codes that include composite micromechanics, composite macromechanics, laminate theory, structural analysis, and multi-factor interaction model. Demonstration of the method includes sample examples for static, thermal, and fracture reliability for a unidirectional metal matrix composite as well as rupture strength and fatigue strength for a high temperature super alloy. Typical results obtained for a unidirectional composite show that the thermal properties are more sensitive to internal local damage, the longitudinal properties degrade slowly with temperature, the transverse and shear properties degrade rapidly with temperature as do rupture strength and fatigue strength for super alloys.

  3. High temperature application of retrievable MWD systems

    SciTech Connect

    Coe, R.; Saito, S.

    1995-12-31

    MWD systems are currently used to monitor the direction of wellbores. MWD systems with higher temperature capabilities are required to meet the needs of deep and geothermal drilling. A technique has been developed for geothermal drilling that allows a fully retrievable MWD system to be used in wells with formation temperatures in excess of 350{degrees}C. This operational technique involves use of the MWD system in combination with operational procedures adapted to cope with the need for continuous directional control while drilling. Descriptions of the drilling environment are given in areas of Japan where high temperature drilling is performed. Possible future requirements are reviewed. The MWD system is described giving current technical specifications and capabilities. The operational method for utilizing the MWD is detailed. A summary of successful applications is discussed and specific case studies given. The efficiency of using the technique is reviewed.

  4. High Temperature Superconductivity and Cold Fusion

    NASA Astrophysics Data System (ADS)

    Rabinowitz, Mario

    There are numerous historical and scientific parallels between high temperature superconductivity (HTSC) and the newly emerging field of cold fusion (CF). Just as the charge carrier effective mass plays an important role in SC, the deuteron effective mass may play a vital role in CF. A new theory including effects of proximity, electron shielding, and decreased effective mass of the fusing nuclei can account for the reported CF results. A quantum-gas model that covers the range from low temperature to superhigh temperature SC indicates an increased Tc with reduced dimensionality. A reduced dimensionality effect may also enhance CF. A relation is shown between CF and the significant cluster-impact fusion experiments.

  5. High refractive index and temperature sensitivity LPGs for high temperature operation

    NASA Astrophysics Data System (ADS)

    Nascimento, I. M.; Gouveia, C.; Jana, Surnimal; Bera, Susanta; Baptista, J. M.; Moreira, Paulo; Biwas, Palas; Bandyopadhyay, Somnath; Jorge, Pedro A. S.

    2013-11-01

    A fiber optic sensor for high sensitivity refractive index and temperature measurement able to withstand temperature up to 450 °C is reported. Two identical LPG gratings were fabricated, whereas one was coated with a high refractive index (~1.78) sol-gel thin film in order to increase its sensitivity to the external refractive index. The two sensors were characterized and compared in refractive index and temperature. Sensitivities of 1063 nm/RIU (1.338 - 1.348) and 260 pm/°C were achieved for refractive index and temperature, respectively.

  6. High-temperature metal-organic magnets.

    PubMed

    Jain, Rajsapan; Kabir, Khayrul; Gilroy, Joe B; Mitchell, Keith A R; Wong, Kin-chung; Hicks, Robin G

    2007-01-18

    For over two decades there have been intense efforts aimed at the development of alternatives to conventional magnets, particularly materials comprised in part or wholly of molecular components. Such alternatives offer the prospect of realizing magnets fabricated through controlled, low-temperature, solution-based chemistry, as opposed to high-temperature metallurgical routes, and also the possibility of tuning magnetic properties through synthesis. However, examples of magnetically ordered molecular materials at or near room temperature are extremely rare, and the properties of these materials are often capricious and difficult to reproduce. Here we present a versatile solution-based route to a new class of metal-organic materials exhibiting magnetic order well above room temperature. Reactions of the metal (M) precursor complex bis(1,5-cyclooctadiene)nickel with three different organics A-TCNE (tetracyanoethylene), TCNQ (7,7,8,8-tetracyanoquinodimethane) or DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone)--proceed via electron transfer from nickel to A and lead to materials containing Ni(II) ions and reduced forms of A in a 2:1 Ni:A ratio--that is, opposite to that of conventional (low Curie temperature) MA(2)-type magnets. These materials also contain oxygen-based species within their architectures. Magnetic characterization of the three compounds reveals spontaneous field-dependent magnetization and hysteresis at room temperature, with ordering temperatures well above ambient. The unusual stoichiometry and striking magnetic properties highlight these three compounds as members of a class of stable magnets that are at the interface between conventional inorganic magnets and genuine molecule-based magnets.

  7. Experiment Provides the Best Look Yet at 'Warm Dense Matter' at Cores of Giant Planets

    SciTech Connect

    2015-03-23

    In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as it transitions into a superhot, highly compressed concoction known as “warm dense matter.”

  8. Plasma synthesis of high temperature ceramic films

    SciTech Connect

    Brown, I.G.; Monteiro, O.R.

    1998-11-01

    Thin films of alumina, chromia, mullite, yttria and zirconia have been synthesized using a plasma-based method called metal plasma immersion ion implantation and deposition (Mepiiid)--a highly versatile plasma deposition technique with ion energy control. Monolithic films (a single ceramic component) and multilayer films (individual layers of different ceramic materials) were formed. The films were characterized for their composition and structure in a number of different ways, and the high temperature performance of the films was explored, particularly for their ability to maintain their integrity and adhesion when subjected to repetitive high temperature thermal cycling up 1100 C. We found that the films retain their adhesion and quality without any apparent degradation with time, even after a large number of cycles; (the tests were extended out to a total of 40 cycles each of 24 hours duration). After repetitive high temperature thermal cycling, the film-substrate adhesion was greater than {approx}70 Mpa, the instrumental limit of measurement, and the interface toughness was approximately 0.8 MPa m{sup 1/2}.

  9. Electrochemical high-temperature gas sensors

    NASA Astrophysics Data System (ADS)

    Saruhan, B.; Stranzenbach, M.; Yüce, A.; Gönüllü, Y.

    2012-06-01

    Combustion produced common air pollutant, NOx associates with greenhouse effects. Its high temperature detection is essential for protection of nature. Component-integration capable high-temperature sensors enable the control of combustion products. The requirements are quantitative detection of total NOx and high selectivity at temperatures above 500°C. This study reports various approaches to detect NO and NO2 selectively under lean and humid conditions at temperatures from 300°C to 800°C. All tested electrochemical sensors were fabricated in planar design to enable componentintegration. We suggest first an impedance-metric gas sensor for total NOx-detection consisting of NiO- or NiCr2O4-SE and PYSZ-electrolyte. The electrolyte-layer is about 200μm thickness and constructed of quasi-single crystalline columns. The sensing-electrode (SE) is magnetron sputtered thin-layers of NiO or NiCr2O4. Sensor sensitivity for detection of total NOx has been measured by applying impedance analysis. The cross-sensitivity to other emission gases such as CO, CO2, CH4 and oxygen (5 vol.%) has been determined under 0-1000ppm NO. Sensor maintains its high sensitivity at temperatures up to 550°C and 600°C, depending on the sensing-electrode. NiO-SE yields better selectivity to NO in the presence of oxygen and have shorter response times comparing to NiCr2O4-SE. For higher temperature NO2-sensing capability, a resistive DC-sensor having Al-doped TiO2-sensing layers has been employed. Sensor-sensitivity towards NO2 and cross-sensitivity to CO has been determined in the presence of H2O at temperatures 600°C and 800°C. NO2 concentrations varying from 25 to 100ppm and CO concentrations from 25 to 75ppm can be detected. By nano-tubular structuring of TiO2, NO2 sensitivity of the sensor was increased.

  10. High-Temperature Piezoelectric Ceramic Developed

    NASA Technical Reports Server (NTRS)

    Sayir, Ali; Farmer, Serene C.; Dynys, Frederick W.

    2005-01-01

    Active combustion control of spatial and temporal variations in the local fuel-to-air ratio is of considerable interest for suppressing combustion instabilities in lean gas turbine combustors and, thereby, achieving lower NOx levels. The actuator for fuel modulation in gas turbine combustors must meet several requirements: (1) bandwidth capability of 1000 Hz, (2) operating temperature compatible with the fuel temperature, which is in the vicinity of 400 F, (3) stroke of approximately 4 mils (100 m), and (4) force of 300 lb-force. Piezoelectric actuators offer the fastest response time (microsecond time constants) and can generate forces in excess of 2000 lb-force. The state-of-the-art piezoceramic material in industry today is Pb(Zr,Ti)O3, called PZT. This class of piezoelectric ceramic is currently used in diesel fuel injectors and in the development of high-response fuel modulation valves. PZT materials are generally limited to operating temperatures of 250 F, which is 150 F lower than the desired operating temperature for gas turbine combustor fuel-modulation injection valves. Thus, there is a clear need to increase the operating temperature range of piezoceramic devices for active combustion control in gas turbine engines.

  11. High resolution modelling of dense water formation in the Northwestern Mediterranean: benefits from an improved initial stratification in summer

    NASA Astrophysics Data System (ADS)

    Estournel, Claude; Testor, Pierre; Damien, Pierre; Mortier, Laurent; Marsaleix, Patrick; Lellouche, Jean-Michel; Ulses, Caroline; Kessouri, Faycal; Raimbault, Patrick; Coppola, Laurent

    2014-05-01

    The period that extends from summer 2012 to summer 2013 was the subject of several field campaigns in the northwestern Mediterranean that allowed to characterize the stratification on a seasonal scale in this region of deep water formation. This period is therefore ideal for testing hydrodynamic models and assessing the accuracy required on initial conditions and meteorological forcing. A 1 km resolution simulation of the vertical stratification evolution of the northwestern Mediterranean between summer 2012 and spring 2013 was conducted. The representation of winter convection was shown to be highly dependent on initial conditions in summer. A method was developed to correct the initial state of the model using the observations of the annual summer cruise of the MOOSE monitoring program and data from ARGO profilers. In addition, an adjustment of the wind helped to better approach winter observations, the criterion being the profile of residual buoyancy, simple index of the potential of the water column to convect more or less deeply and rapidly. The simulation obtained after correction of the initial conditions and wind forcing allowed to accurately represent the characteristics of the water masses formed during the convective period, the area concerned by convection and its timing. We will first present the methodology used to correct the initial state of the simulation, and then the validation of the simulation based on the observations from the DEWEX cruise (MERMEX program) and from profilers deployed in the frame of the HyMeX program. Then the volume of dense water formed and its characteristics will be quantified as well as their sensitivity to initial conditions.

  12. Dispersion-optimized optical fiber for high-speed long-haul dense wavelength division multiplexing transmission

    NASA Astrophysics Data System (ADS)

    Wu, Jindong; Chen, Liuhua; Li, Qingguo; Wu, Wenwen; Sun, Keyuan; Wu, Xingkun

    2011-07-01

    Four non-zero-dispersion-shifted fibers with almost the same large effective area (Aeff) and optimized dispersion properties are realized by novel index profile designing and modified vapor axial deposition and modified chemical vapor deposition processes. An Aeff of greater than 71 μm2 is obtained for the designed fibers. Three of the developed fibers with positive dispersion are improved by reducing the 1550nm dispersion slope from 0.072ps/nm2/km to 0.063ps/nm2/km or 0.05ps/nm2/km, increasing the 1550nm dispersion from 4.972ps/nm/km to 5.679ps/nm/km or 7.776ps/nm/km, and shifting the zero-dispersion wavelength from 1500nm to 1450nm. One of these fibers is in good agreement with G655D and G.656 fibers simultaneously, and another one with G655E and G.656 fibers; both fibers are beneficial to high-bit long-haul dense wavelength division multiplexing systems over S-, C-, and L-bands. The fourth developed fiber with negative dispersion is also improved by reducing the 1550nm dispersion slope from 0.12ps/nm2/km to 0.085ps/nm2/km, increasing the 1550nm dispersion from -4ps/nm/km to -6.016ps/nm/km, providing facilities for a submarine transmission system. Experimental measurements indicate that the developed fibers all have excellent optical transmission and good macrobending and splice performances.

  13. Nontrivial center dominance in high temperature QCD

    NASA Astrophysics Data System (ADS)

    Ishikawa, K.-I.; Iwasaki, Y.; Nakayama, Yu; Yoshie, T.

    2016-07-01

    We investigate the properties of quarks and gluons above the chiral phase transition temperature Tc, using the renormalization group (RG) improved gauge action and the Wilson quark action with two degenerate quarks mainly on a 323 × 16 lattice. In the one-loop perturbation theory, the thermal ensemble is dominated by the gauge configurations with effectively Z(3) center twisted boundary conditions, making the thermal expectation value of the spatial Polyakov loop take a nontrivial Z(3) center. This is in agreement with our lattice simulation of high temperature quantum chromodynamics (QCD). We further observe that the temporal propagator of massless quarks at extremely high temperature β = 100.0(T ≃ 1058T c) remarkably agrees with the temporal propagator of free quarks with the Z(3) twisted boundary condition for t/Lt ≥ 0.2, but differs from that with the Z(3) trivial boundary condition. As we increase the mass of quarks mq, we find that the thermal ensemble continues to be dominated by the Z(3) twisted gauge field configurations as long as mq ≤ 3.0T and above that the Z(3) trivial configurations come in. The transition is similar to what we found in the departure from the conformal region in the zero-temperature many-flavor conformal QCD on a finite lattice by increasing the mass of quarks.

  14. Evaluation of high temperature capacitor dielectrics

    NASA Technical Reports Server (NTRS)

    Hammoud, Ahmad N.; Myers, Ira T.

    1992-01-01

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  15. Medium Deep High Temperature Heat Storage

    NASA Astrophysics Data System (ADS)

    Bär, Kristian; Rühaak, Wolfram; Schulte, Daniel; Welsch, Bastian; Chauhan, Swarup; Homuth, Sebastian; Sass, Ingo

    2015-04-01

    Heating of buildings requires more than 25 % of the total end energy consumption in Germany. Shallow geothermal systems for indirect use as well as shallow geothermal heat storage systems like aquifer thermal energy storage (ATES) or borehole thermal energy storage (BTES) typically provide low exergy heat. The temperature levels and ranges typically require a coupling with heat pumps. By storing hot water from solar panels or thermal power stations with temperatures of up to 110 °C a medium deep high temperature heat storage (MDHTS) can be operated on relatively high temperature levels of more than 45 °C. Storage depths of 500 m to 1,500 m below surface avoid conflicts with groundwater use for drinking water or other purposes. Permeability is typically also decreasing with greater depth; especially in the crystalline basement therefore conduction becomes the dominant heat transport process. Solar-thermal charging of a MDHTS is a very beneficial option for supplying heat in urban and rural systems. Feasibility and design criteria of different system configurations (depth, distance and number of BHE) are discussed. One system is designed to store and supply heat (300 kW) for an office building. The required boreholes are located in granodioritic bedrock. Resulting from this setup several challenges have to be addressed. The drilling and completion has to be planned carefully under consideration of the geological and tectonical situation at the specific site.

  16. Noise temperature in graphene at high frequencies

    NASA Astrophysics Data System (ADS)

    Rengel, Raúl; Iglesias, José M.; Pascual, Elena; Martín, María J.

    2016-07-01

    A numerical method for obtaining the frequency-dependent noise temperature in monolayer graphene is presented. From the mobility and diffusion coefficient values provided by Monte Carlo simulation, the noise temperature in graphene is studied up to the THz range, considering also the influence of different substrate types. The influence of the applied electric field is investigated: the noise temperature is found to increase with the applied field, dropping down at high frequencies (in the sub-THz range). The results show that the low-frequency value of the noise temperature in graphene on a substrate tends to be reduced as compared to the case of suspended graphene due to the important effect of remote polar phonon interactions, thus indicating a reduced emitted noise power; however, at very high frequencies the influence of the substrate tends to be significantly reduced, and the differences between the suspended and on-substrate cases tend to be minimized. The values obtained are comparable to those observed in GaAs and semiconductor nitrides.

  17. Evaluation of high temperature capacitor dielectrics

    NASA Astrophysics Data System (ADS)

    Hammoud, Ahmad N.; Myers, Ira T.

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  18. Using Formaldehyde to Create High Resolution Temperature Maps of CMZ Clouds

    NASA Astrophysics Data System (ADS)

    Castaño, Jimmy

    2016-01-01

    80% of the dense molecular gas in our Galaxy resides in the central few hundred parsecs, known as the Central Molecular Zone (CMZ). From our understanding of star formation, we would expect a comparatively high star formation rate in this region, but the estimates so far indicate that only 5-10% of the star formation in our Galaxy occurs there. There are a number of physical effects that may be causing this, but we particularly wish to investigate the role of the temperature of the gas - which initial estimates put at an average of 50-100 K or about a factor of 5 higher than elsewhere in the disk. Armed with the data taken by the SMA Legacy Survey of the CMZ, we aim to compare parameters two transition lines for the dense gas tracer H2CO which are particularly sensitive to temperature to measure the gas temperature on 0.2 pc scales. Ultimately we provide a high resolution temperature map for a set of clouds in the CMZ dubbed "the three little pigs" to provide an initial comparison with similar work done with ammonia tracers in order to pave the way for a high resolution temperature map of the entire CMZ.

  19. High temperature furnace modeling and performance verifications

    NASA Technical Reports Server (NTRS)

    Smith, James E., Jr.

    1988-01-01

    Analytical, numerical and experimental studies were performed on two classes of high temperature materials processing furnaces. The research concentrates on a commercially available high temperature furnace using zirconia as the heating element and an arc furnace based on a ST International tube welder. The zirconia furnace was delivered and work is progressing on schedule. The work on the arc furnace was initially stalled due to the unavailability of the NASA prototype, which is actively being tested aboard the KC-135 experimental aircraft. A proposal was written and funded to purchase an additional arc welder to alleviate this problem. The ST International weld head and power supply were received and testing will begin in early November. The first 6 months of the grant are covered.

  20. Precision control of high temperature furnaces

    SciTech Connect

    Pollock, G.G.

    1994-12-31

    It is an object of the present invention to provide precision control of high temperature furnaces. It is another object of the present invention to combine the power of two power supplies of greatly differing output capacities in a single furnace. This invention combines two power supplies to control a furnace. A main power supply heats the furnace in the traditional manner, while the power from the auxiliary supply is introduced as a current flow through charged particles existing due to ionized gas or thermionic emission. The main power supply provides the bulk heating power and the auxiliary supply provides a precise and fast power source such that the precision of the total power delivered to the furnace is improved. Further, this invention comprises a means for high speed measurement of temperature of the process by the method of measuring the amount of current flow in a deliberately induced charged particle current.

  1. High temperature superconductors for magnetic suspension applications

    NASA Technical Reports Server (NTRS)

    Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

    1994-01-01

    High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

  2. High temperature superconductor materials and applications

    NASA Technical Reports Server (NTRS)

    Doane, George B., III. (Editor); Banks, Curtis; Golben, John

    1991-01-01

    One of the areas concerned itself with the investigation of the phenomena involved in formulating and making in the laboratory new and better superconductor material with enhanced values of critical current and temperature. Of special interest were the chemistry, physical processes, and environment required to attain these enhanced desirable characteristics. The other area concerned itself with producing high temperature superconducting thin films by pulsed laser deposition techniques. Such films are potentially very useful in the detection of very low power signals. To perform this research high vacuum is required. In the course of this effort, older vacuum chambers were maintained and used. In addition, a new facility is being brought on line. This latter activity has been replete with the usual problems of bringing a new facility into service. Some of the problems are covered in the main body of this report.

  3. Hole-doped cuprate high temperature superconductors

    NASA Astrophysics Data System (ADS)

    Chu, C. W.; Deng, L. Z.; Lv, B.

    2015-07-01

    Hole-doped cuprate high temperature superconductors have ushered in the modern era of high temperature superconductivity (HTS) and have continued to be at center stage in the field. Extensive studies have been made, many compounds discovered, voluminous data compiled, numerous models proposed, many review articles written, and various prototype devices made and tested with better performance than their nonsuperconducting counterparts. The field is indeed vast. We have therefore decided to focus on the major cuprate materials systems that have laid the foundation of HTS science and technology and present several simple scaling laws that show the systematic and universal simplicity amid the complexity of these material systems, while referring readers interested in the HTS physics and devices to the review articles. Developments in the field are mostly presented in chronological order, sometimes with anecdotes, in an attempt to share some of the moments of excitement and despair in the history of HTS with readers, especially the younger ones.

  4. Magnetic suspension using high temperature superconducting cores

    NASA Technical Reports Server (NTRS)

    Scurlock, R. G.

    1992-01-01

    The development of YBCO high temperature superconductors, in wire and tape forms, is rapidly approaching the point where the bulk transport current density j vs magnetic field H characteristics with liquid nitrogen cooling will enable its use in model cores. On the other hand, BSCCO high temperature superconductor in wire form has poor j-H characteristics at 77 K today, although with liquid helium or hydrogen cooling, it appears to be superior to NbTi superconductor. Since liquid nitrogen cooling is approx. 100 times cheaper than liquid helium cooling, the use of YBCO is very attractive for use in magnetic suspension. The design is discussed of a model core to accommodate lift and drag loads up to 6000 and 3000 N respectively. A comparison is made between the design performance of a liquid helium cooled NbTi (or BSCCO) superconducting core and a liquid nitrogen cooled YBCO superconducting core.

  5. High current density and longtime stable field electron transfer from large-area densely arrayed graphene nanosheet-carbon nanotube hybrids.

    PubMed

    Deng, Jian-Hua; Cheng, Lin; Wang, Fan-Jie; Li, Guo-Zheng; Li, De-Jun; Cheng, Guo-An

    2014-12-10

    Achieving high current and longtime stable field emission from large area (larger than 1 mm(2)), densely arrayed emitters is of great importance in applications for vacuum electron sources. We report here the preparation of graphene nanosheet-carbon nanotube (GNS-CNT) hybrids by following a process of iron ion prebombardment on Si wafers, catalyst-free growth of GNSs on CNTs, and high-temperature annealing. Structural observations indicate that the iron ion prebombardment influences the growth of CNTs quite limitedly, and the self-assembled GNSs sparsely distributed on the tips of CNTs with their sharp edges unfolded outside. The field emission study indicates that the maximum emission current density (Jmax) is gradually promoted after these treatments, and the composition with GNSs is helpful for decreasing the operation fields of CNTs. An optimal Jmax up to 85.10 mA/cm(2) is achieved from a 4.65 mm(2) GNS-CNT sample, far larger than 7.41 mA/cm(2) for the as-grown CNTs. This great increase of Jmax is ascribed to the reinforced adhesion of GNS-CNT hybrids to substrates. We propose a rough calculation and find that this adhesion is promoted by 7.37 times after the three-step processing. We consider that both the ion prebombardment produced rough surface and the wrapping of CNT foot by catalyst residuals during thermal processing are responsible for this enhanced adhesion. Furthermore, the three-step prepared GNS-CNT hybrids present excellent field emission stability at high emission current densities (larger than 20 mA/cm(2)) after being perfectly aged. PMID:25335851

  6. Trends in Surface Temperature at High Latitudes

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.

    2012-01-01

    The earliest signal of a climate change is expected to be found in the polar regions where warming is expected to be amplified on account of ice-albedo feedbacks associated with the high reflectivity of snow and ice. Because of general inaccessibility, there is a general paucity of in situ data and hence the need to use satellite data to observe the large-scale variability and trends in surface temperature in the region. Among the most important sensors for monitoring surface temperature has been the Advanced Very High Resolution Radiometer (AVHRR) which was first launched in 1978 and has provided continuous thermal infrared data since 1981. The top of the atmosphere data are converted to surface temperature data through various schemes that accounts for the unique atmospheric and surface conditions in the polar regions. Among the highest source of error in the data is cloud masking which is made more difficult in the polar region because of similar Signatures of clouds and snow lice covered areas. The availability of many more channels in the Moderate Resolution Imaging Spectroradiometer (MODIS) launched on board Terra satellite in December 1999 and on board Aqua in May 2002 (e.g., 36 visible and infrared channels compared to 5 for AVHRR) made it possible to minimize the error. Further capabilities were introduced with the Advanced Microwave Scanning Radiometer (AMSR) which has the appropriate frequency channels for the retrieval of sea surface temperature (SST). The results of analysis of the data show an amplified warming in the Arctic region, compared with global warming. The spatial distribution of warming is, however, not uniform and during the last 3 decades, positive temperature anomalies have been most pronounced in North America, Greenland and the Arctic basin. Some regions of the Arctic such as Siberia and the Bering Sea surprisingly show moderate cooling but this may be because these regions were anomalously warm in the 1980s when the satellite record

  7. A high temperature superconductivity communications flight experiment

    NASA Technical Reports Server (NTRS)

    Ngo, P.; Krishen, K.; Arndt, D.; Raffoul, G.; Karasack, V.; Bhasin, K.; Leonard, R.

    1992-01-01

    The proposed high temperature superconductivity (HTSC) millimeter-wave communications flight experiment from the payload bay of the Space Shuttle Orbiter to the Advanced Communications Technology Satellite (ACTS) in geosynchronous orbit is described. The experiment will use a Ka-band HTSC phased array antenna and front-end electronics to receive a downlink communications signal from the ACTS. The discussion covers the system configuration, a description of the ground equipment, the spacecraft receiver, link performance, thermal loading, and the superconducting antenna array.

  8. Atomic absorption spectroscopy with high temperature flames.

    PubMed

    Willis, J B

    1968-07-01

    An account is given of the history of the development of high temperature flames for the atomic absorption measurement of metals forming refractory oxides. The principles governing the design of premix burners for such flames, and the relative merits of different types of nebulizer burner systems are described. After a brief account of the structure and emission characteristics of the premixed oxygen-acetylene and nitrous oxide-acetylene flames, the scope and limitations of the latter flame in chemical analysis are discussed.

  9. Intermetallic-Based High-Temperature Materials

    SciTech Connect

    Sikka, V.K.

    1999-04-25

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  10. Establishment of Harrop, High-Temperature Viscometer

    SciTech Connect

    Schumacher, R.F.

    1999-11-05

    This report explains how the Harrop, High-Temperature Viscometer was installed, calibrated, and operated. This report includes assembly and alignment of the furnace, viscometer, and spindle, and explains the operation of the Brookfield Viscometer, the Harrop furnace, and the UDC furnace controller. Calibration data and the development of the spindle constant from NIST standard reference glasses is presented. A simple operational procedure is included.

  11. High temperature, flexible, fiber-preform seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor); Strocky, Paul J. (Inventor)

    1992-01-01

    A seal is mounted in a rectangular groove in a movable structural panel. The seal comprises a fiber preform constructed of multiple layers of fiber having a uniaxial core. Helical fibers are wound over the core. The fibers are of materials capable of withstanding high temperatures and are both left-hand and right-hand wound. An outer layer wrapped over said helical fibers prevents abrasion damage.

  12. Thermal fuse for high-temperature batteries

    DOEpatents

    Jungst, Rudolph G.; Armijo, James R.; Frear, Darrel R.

    2000-01-01

    A thermal fuse, preferably for a high-temperature battery, comprising leads and a body therebetween having a melting point between approximately 400.degree. C. and 500.degree. C. The body is preferably an alloy of Ag--Mg, Ag--Sb, Al--Ge, Au--In, Bi--Te, Cd--Sb, Cu--Mg, In--Sb, Mg--Pb, Pb--Pd, Sb--Zn, Sn--Te, or Mg--Al.

  13. Passivation Of High-Temperature Superconductors

    NASA Technical Reports Server (NTRS)

    Vasquez, Richard P.

    1991-01-01

    Surfaces of high-temperature superconductors passivated with native iodides, sulfides, or sulfates formed by chemical treatments after superconductors grown. Passivating compounds nearly insoluble in and unreactive with water and protect underlying superconductors from effects of moisture. Layers of cuprous iodide and of barium sulfate grown. Other candidate passivating surface films: iodides and sulfides of bismuth, strontium, and thallium. Other proposed techniques for formation of passivating layers include deposition and gas-phase reaction.

  14. High Temperature Decomposition of Hydrogen Peroxide

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2004-01-01

    Nitric oxide (NO) is oxidized into nitrogen dioxide (NO2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydropemxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

  15. High temperature decomposition of hydrogen peroxide

    NASA Technical Reports Server (NTRS)

    Parrish, Clyde F. (Inventor)

    2005-01-01

    Nitric oxide (NO) is oxidized into nitrogen dioxide (NO2) by the high temperature decomposition of a hydrogen peroxide solution to produce the oxidative free radicals, hydroxyl and hydroperoxyl. The hydrogen peroxide solution is impinged upon a heated surface in a stream of nitric oxide where it decomposes to produce the oxidative free radicals. Because the decomposition of the hydrogen peroxide solution occurs within the stream of the nitric oxide, rapid gas-phase oxidation of nitric oxide into nitrogen dioxide occurs.

  16. Caldron For High-Temperature Alloys

    NASA Technical Reports Server (NTRS)

    Geringer, Henry J.

    1989-01-01

    Induction-heated caldron melts high-temperature alloys. Prevents sort of contamination of melts occurring during arc melting in ceramic crucibles. Liquefies 200 grams of solid metal components of alloy like niobium aluminum and makes alloy homogeneous in less than 3 minutes. Plugged sleeve constitutes main body of caldron. Coolant flows through sleeve to prevent it from melting. Mandrel-wound induction coils adjusted to tune source of power. Also serves as mold for casting alloys into such shapes as bars.

  17. High Temperature Strain Gage Calibration Fixture

    NASA Technical Reports Server (NTRS)

    Vranas, T. (Inventor)

    1976-01-01

    An apparatus and method are described for calibrating high temperature strain gases which serve for both dead weight and constant deflection measurements. A cantilever support arm allows the test unit to slide into a furnace while one end is subjected to bending strain either by hanging weights upon it or by deflecting it with a push rod. The dual nature of the fixture permits both tests to be run without change of the test specimen or removal from the furnace.

  18. Nickel alloys combat high-temperature corrosion

    SciTech Connect

    Agarwal, D.C.; Herda, W.R.; Brill, U.

    1995-10-01

    During the last few decades, a better understanding of alloying effects, advances in melting technology, and the development of controlled thermomechanical processing have led to new and improved high-temperature alloys. Most such alloys have sufficient amounts of chromium (with or without additions of aluminum or silicon) to form chromium oxide, alumina, and/or silica protective oxide scales, which provide resistance to environmental degradation. However, oxides cannot protect against failure by creep, mechanical or thermal fatigue, thermal shock, or embrittlement. In the real world, failure is typically caused by a combination of two or more attack modes, which synergistically accelerate degradation. To counter these attacks, two new nickel-base alloys have been developed, in which high-temperature corrosion resistance has been optimized by the careful addition of elements such as chromium, aluminum, silicon, and rare earths. They provide economical and reliable solutions to attack by oxygen, sulfur, halogens, carbon compounds, and nitrogen in a range of high-temperature applications. For example, Alloy 602CA is utilized in heat treating equipment, catalytic automotive parts, and chemical processing apparatus. Alloy 45TM has been successfully used in coal gasification equipment, incinerators, refineries, and process machinery involving severe sulfidizing conditions.

  19. High Temperature VARTM of Phenylethynyl Terminated Imides

    NASA Technical Reports Server (NTRS)

    Ghose, Sayata; Cano, Roberto J.; Watson, Kent A.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.

    2009-01-01

    Depending on the part type and quantity, fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) can be more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, the desired void fraction of less than 2% has not yet been achieved. In the current study, two PETI resins, LaRC PETI-330 and LaRC PETI-8 have been used to make test specimens using HT-VARTM. The resins were infused into ten layers of IM7-6K carbon fiber 5-harness satin fabric at 260 C or 280 C and cured at temperature up to 371 C. Initial runs yielded composites with high void content, typically greater than 7% by weight. A thermogravimetric-mass spectroscopic study was conducted to determine the source of volatiles leading to high porosity. It was determined that under the thermal cycle used for laminate fabrication, the phenylethynyl endcap was undergoing degradation leading to volatile evolution. This finding was unexpected as high quality composite laminates have been fabricated under higher pressures using these resin systems. The amount of weight loss experienced during the thermal cycle was only about 1% by weight, but this leads to a significant amount of volatiles in a closed system. By modifying the thermal cycle used in laminate fabrication, the void content was significantly reduced (typically 3% or less). The results of this work are presented herein.

  20. High temperature inorganic membranes for separating hydrogen

    SciTech Connect

    Fain, D.E.; Roettger, G.E.

    1995-08-01

    Effort has continued to accumulate data on the transport of gases over the temperature range from room temperature to 275{degrees}C with inorganic membranes having a range of pore radii from approximately 0.25 nm to 3 mn. An experimental alumina membrane having an estimated mean pore radius of 0.25 nm has been fabricated and tested. Extensive testing of this membrane indicated that the separation factor for helium and carbon tetrafluoride at 250{degrees}C was 59 and the extrapolated high temperature separation factor was 1,193. For safety reasons, earlier flow measurements concentrated on helium, carbon dioxide, and carbon tetrafluoride. New data have been acquired with hydrogen to verify the agreement with the other gases. During the measurements with hydrogen, it was noted that a considerable amount of moisture was present in the test gas. The source of this moisture and its effect on permeance was examined. Improvements were implemented to the flow test system to minimize the water content of the hydrogen test gas, and subsequent flow measurements have shown excellent results with hydrogen. The extrapolation of separation factors as a function of temperature continues to show promise as a means of using the hard sphere model to determine the pore size of membranes. The temperature dependence of helium transport through membranes appears to be considerably greater than other gases for the smallest pore sizes. The effort to extend temperature dependence to the hard sphere model continues to be delayed, primarily because of a lack of adequate adsorption data.

  1. Precipitation Hardenable High Temperature Shape Memory Alloy

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald Dean (Inventor); Draper, Susan L. (Inventor); Nathal, Michael V. (Inventor); Crombie, Edwin A. (Inventor)

    2010-01-01

    A composition of the invention is a high temperature shape memory alloy having high work output, and is made from (Ni+Pt+Y),Ti(100-x) wherein x is present in a total amount of 49-55 atomic % Pt is present in a total amount of 10-30 atomic %, Y is one or more of Au, Pd. and Cu and is present in a total amount of 0 to 10 atomic %. The alloy has a matrix phase wherein the total concentration of Ni, Pt, and the one or more of Pd. Au, and Cu is greater than 50 atomic %.

  2. Structural relationships in high temperature superconductors

    SciTech Connect

    Schuller, I.K.; Segre, C.U.; Hinks, D.G.; Jorgensen, J.D.; Soderholm, L.; Beno, M.; Zhang, K.

    1987-09-01

    The recent discovery of two types of metallic copper oxide compounds which are superconducting to above 90/sup 0/K has renewed interest in the search for new high temperature superconducting materials. It is significant that both classes of compounds, La/sub 2-x/Sr/sub x/CuO/sub 4-y/ and YBa/sub 2/Cu/sub 3/O/sub 7-delta/ are intimately related to the extensively studied perovskite family. Both compounds contain highly oxidized, covalently bonded Cu-O sublattices, however, they differ in geometry. In this paper we discuss the relationship of these features to the superconducting properties. 30 refs., 6 figs.

  3. High temperature aqueous stress corrosion testing device

    DOEpatents

    Bornstein, A.N.; Indig, M.E.

    1975-12-01

    A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston.

  4. High Temperature Wear of Advanced Ceramics

    NASA Technical Reports Server (NTRS)

    DellaCorte, C.

    2005-01-01

    It was initially hypothesized that advanced ceramics would exhibit favorable high te- friction and wear properties because of their high hot hardness and low achievable surface roughness welding observed in metals does not occur in ceramics. More recent tribological studies of many nitride, carbide, oxide and composite ceramics, however, have revealed that ceramics often exhibit high friction and wear in non-lubricated, high temperature sliding contacts. A summary is given to measure friction and wear factor coefficients for a variety of ceramics from self mated ceramic pin-on-disk tests at temperatures from 25 to up to 1200 C. Observed steady state friction coefficients range from about 0.5 to 1.0 or above. Wear factor coefficients are also very high and range from about to 10(exp -5) to 10(exp -2) cubic millimeters per N-m. By comparison, oil lubricated steel sliding results in friction coefficients of 0.1 or less and wear factors less than 10(exp -9) cubic millimeters per N-m.

  5. High-temperature alloys for high-power thermionic systems

    SciTech Connect

    Shin, Kwang S.; Jacobson, D.L.; D'cruz, L.; Luo, Anhua; Chen, Bor-Ling.

    1990-08-01

    The need for structural materials with useful strength above 1600 k has stimulated interest in refractory-metal alloys. Tungsten possesses an extreme high modulus of elasticity as well as the highest melting temperature among metals, and hence is being considered as one of the most promising candidate materials for high temperature structural applications such as space nuclear power systems. This report is divided into three chapters covering the following: (1) the processing of tungsten base alloys; (2) the tensile properties of tungsten base alloys; and (3) creep behavior of tungsten base alloys. Separate abstracts were prepared for each chapter. (SC)

  6. LHDAC setup for high temperature and high pressure studies

    SciTech Connect

    Patel, Nishant N. Meenakshi, S. Sharma, Surinder M.

    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.

  7. High Temperature VARTM of Phenylethynyl Terminated Imides

    NASA Technical Reports Server (NTRS)

    Cano, Roberto J.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.; Ghose, Sayata; Watson, Kent A.

    2009-01-01

    Fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, the desired void fraction of less than 2% has not yet been achieved. In the current study, two PETI resins, LaRC PETI-330 and LaRC PETI-8 have been used to make test specimens using HT-VARTM. The resins were infused into ten layers of IM7-6K carbon fiber 5-harness satin fabric at 260 C or 280 C and cured at 371 C. Initial runs yielded composites with high void content, typically greater than 7% by weight. A thermogravimetric-mass spectroscopic study was conducted to determine the source of volatiles leading to high porosity. It was determined that under the thermal cycle used for laminate fabrication, the phenylethynyl endcap was undergoing degradation leading to volatile evolution. By modifying the thermal cycle used in laminate fabrication, the void content was reduced significantly (typically approximately 3%). Densities of the composites were determined using a density gradient column and the glass transition temperatures of the cured composites were measured by dynamic mechanical analysis. Photomicrographs of the panels were taken and void contents were determined by acid digestion. The results of this work are presented herein.

  8. Improved Seals for High Temperature Airframe Applications

    NASA Technical Reports Server (NTRS)

    DeMange, Jeffrey J.; Dunlap, Patrick H.; Steinetz, Bruce M.

    2006-01-01

    Current thermal barrier seals, such as those used on the Space Shuttle, are insufficient to fully meet the demands of future hypersonic vehicles and reentry spacecraft. Previous investigations have demonstrated limited usage temperatures, as evidenced by a decreased ability to maintain sealing effectiveness at high temperatures (i.e., inadequate resiliency). In order to improve resiliency at elevated temperatures, Rene 41 (Allvac) was substituted for Inconel X-750 (Special Metals Corp.) as the spring tube material in the existing seal design. A seal construction incorporating the Rene 41 spring tube was fabricated and tested against the baseline Inconel X-750 spring tube seal. Although resiliency improvements were not as dramatic as in previous tests with the spring tubes alone, seals incorporating the Rene 41 spring tube exhibited an average 20 percent resiliency enhancement up to 1750 F when compared to seals containing the Inconel spring tube. In addition, the seals with the Rene 41 spring tubes showed less reduction in resiliency as temperatures increased above 1200 F. Results also indicated the Saffil (Saffil Ltd.) insulation in the core of the seal contributed more to resiliency than previously thought. Leakage data did not demonstrate an improvement with the seal containing the Rene 41 spring tube. However, based upon resiliency results, one could reasonably expect the Rene 41 version of the seal to track gap openings over a wider range. Therefore it would exhibit lower leakage than the Inconel X-750 version as the seal gap opens during a typical mission.

  9. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  10. High Temperature Materials for Chemical Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Elam, Sandra; Hickman, Robert; O'Dell, Scott

    2007-01-01

    Radiation or passively cooled thrust chambers are used for a variety of chemical propulsion functions including apogee insertion, reaction control for launch vehicles, and primary propulsion for planetary spacecraft. The performance of these thrust chambers is limited by the operating temperature of available materials. Improved oxidation resistance and increased operating temperatures can be achieved with the use of thermal barrier coatings such as zirconium oxide (ZrO2) and hafnium oxide (HfO2). However, previous attempts to include these materials showed cracking and spalling of the oxide layer due to poor bonding. Current research at NASA's Marshall Space Flight Center (MSFC) has generated unique, high temperature material options for in-space thruster designs that are capable of up to 2500 C operating temperatures. The research is focused on fabrication technologies to form low cost Iridium,qF_.henium (Ir/Re) components with a ceramic hot wall created as an integral, functionally graded material (FGM). The goal of this effort is to further de?celop proven technologies for embedding a protective ceramic coating within the Ir/Re liner to form a robust functional gradient material. Current work includes the fabrication and testing of subscale samples to evaluate tensile, creep, thermal cyclic/oxidation, and thermophysical material properties. Larger test articles have also being fabricated and hot-fire tested to demonstrate the materials in prototype thrusters at 1O0 lbf thrust levels.

  11. New high temperature cross linking monomers. [for polymer matrix composite materials

    NASA Technical Reports Server (NTRS)

    Scola, D. A.

    1978-01-01

    Several PMR-polyimide resins capable of being processed at a maximum temperature of 232 C to 288 C without sacrifice of high temperature capability were developed. Four monomethyl esters were synthesized and characterized for use in the crosslinking studies. The infrared and DSC studies of each crosslinker suggested that curing could be accomplished at 288 C. However, fabrication of dense, void free polymer specimens required a temperature of 316 C and a pressure of 0.69 MPa (100 psi). Crosslinkers were evaluated in Celion 6000/PMR polyimide composites. These composites were characterized at RT, 288 C and 316 C initially and after isothermal aging at 288 C and 316 C for several hundred hours. The results suggest that both PMR systems are promising candidates as matrices for addition type polyimide composites. It is demonstrated that alternate crosslinkers are feasible, but mechanisms to lower the crosslinking temperature must be developed to provide lower temperature processing PMR-type polyimides.

  12. High temperature behavior of zirconium germanates

    SciTech Connect

    Utkin, A.V.; Baklanova, N.I.; Vasilyeva, I.G.

    2013-05-01

    The high temperature behavior of zirconium germanates ZrGeO₄ and Zr₃GeO₈ up to 2300 °C has been studied using the original photoemission thermal analysis technique with the comprehensive physicochemical study of solid and gaseous intermediate and final products. The two-stage process of incongruent sublimation of GeO₂ was established and the phase boundary of the homogeneity range for ZrGeO₄ and Zr₃GeO₈ were deduced from the thermal analysis, X-ray diffraction and Raman spectroscopy studies. A high tendency to sintering of the final ZrO₂ product is discussed. - Graphical abstract: The decomposition of zirconium germanates leads to the formation of gaseous GeO₂ and solid sintered ZrO₂ and occurs via two stages with the formation of intermediate ZrO₂-rich solid solution. Highlights: •Thermal behavior of ZrGeO₄ and Zr₃GeO₈ was studied using the original thermal analysis technique in wide temperature range. •The decomposition occurs via two stages with the formation of intermediate ZrO₂-rich solid solution. •The decomposition of zirconium germanates leads to the formation of gaseous GeO₂ and solid sintered ZrO₂. •The temperature of decomposition is strongly depended on the total gas pressure.

  13. NOVEL CERAMIC MEMBRANE FOR HIGH TEMPERATURE CARBON DIOXIDE SEPARATION

    SciTech Connect

    Jun-ichi Ida; Zhaohui Yang; Jerry Y.S. Lin

    2001-09-01

    The Objective of this research program is to develop a dense, non porous ceramic membrane for separation of carbon dioxide from flue gas at high temperatures (400-600 C). The research has been focused on addressing several fundamental issues of lithium zirconate (Li{sub 2}ZrO{sub 3}). In the 2nd half research, we conducted various kinds of experiments to understand the CO{sub 2} sorption/desorption mechanism on the pure and modified Li{sub 2}ZrO{sub 3} with the help of TGA, DSC TGA and XRD. DSC TGA results suggest that the melting of Li/K carbonates mixture may play an important role in rapid CO{sub 2} sorption in the case of modified lithium zirconate. The CO{sub 2} desorption experiments show that CO{sub 2} desorption from the modified lithium zirconate follows the same mechanism as that from the pure lithium zirconate. This is different from the CO{sub 2} adsorption on the pure and modified lithium zirconates.

  14. Compatibility Issues for a High Temperature Dual Coolant Blanket

    SciTech Connect

    Pint, Bruce A

    2007-01-01

    One proposed U.S. test blanket module (TBM) for ITER uses ferritic-martensitic alloys with both eutectic Pb-Li and He coolants at {approx}475 C. In order for this blanket concept to operate at higher temperatures ({approx}750 C) for a DEMO-type reactor, several Pb-Li compatibility issues need to be addressed. A SiC/SiC composite flow channel insert is proposed to reduce the steel dissolution rate (and the magnetohydrodynamic pressure drop). Prior capsule testing examined dense, high-purity SiC in Pb-Li at 800-1200 C and found detectable levels of Si in the Pb-Li after 2,000h at 1100 C and 1,000h at 1200 C. Current capsule experiments are examining several different SiC/SiC composite materials at 1000 C. Another issue involves Pb-Li transport between the first wall and heat exchanger. Aluminide coatings on type 316 stainless steel and Al-containing alloys capable of forming an external alumina scale have been studied in capsule experiments at 700 and 800 C for 1,000h. Model aluminide coatings made by chemical vapor deposition reduced the dissolution rate for 316SS at 800 C by a factor of 50.

  15. The NASA high temperature superconductivity program

    NASA Technical Reports Server (NTRS)

    Sokoloski, Martin M.; Romanofsky, Robert R.

    1990-01-01

    It has been recognized from the onset that high temperature superconductivity held great promise for major advances across a broad range of NASA interests. The current effort is organized around four key areas: communications and data, sensors and cryogenics, propulsion and power, and space materials technology. Recently, laser ablated YBa2Cu3O(7-x) films on LaAIO produced far superior RF characteristics when compared to metallic films on the same substrate. This achievement has enabled a number of unique microwave device applications, such as low insertion loss phase shifters and high Q filters. Melt texturing and melt quenched techniques are being used to produce bulk materials with optimized magnetic properties. These yttrium enriched materials possess enhanced flux pinning characteristics and will lead to prototype cryocooler bearings. Significant progress has also occurred in bolometer and current lead technology. Studies are being conducted to evaluate the effect of high temperature superconducting materials on the performance and life of high power magneto-plasma-dynamic thrusters. Extended studies were also performed to evaluate the benefit of superconducting magnetic energy storage for LEO space station, lunar and Mars mission applications. The project direction and level of effort of the program are also described.

  16. Structural application of high strength, high temperature ceramics

    NASA Technical Reports Server (NTRS)

    Hall, W. B.

    1982-01-01

    The operation of rocket engine turbine pumps is limited by the temperature restrictions of metallic components used in the systems. Mechanical strength and stability of these metallic components decrease drastically at elevated temperatures. Ceramic materials that retain high strength at high temperatures appear to be a feasible alternate material for use in the hot end of the turbopumps. This project identified and defined the processing parameters that affected the properties of Si3N4, one of candidate ceramic materials. Apparatus was assembled and put into operation to hot press Si3N4 powders into bulk material for in house evaluation. A work statement was completed to seek outside contract services to design, manufacture, and evaluate Si3N4 components in the service environments that exists in SSME turbopumps.

  17. High-Frequency, High-Temperature Fretting Experiments

    NASA Technical Reports Server (NTRS)

    Matlik, J. F.; Farris, T. N.; Haake, F. K.; Swanson, G. R.; Duke, G. C.

    2005-01-01

    Fretting is a structural damage mechanism observed when two nominally clamped surfaces are subjected to an oscillatory loading. A critical location for fretting induced damage has been identified at the blade/disk and blade/damper interfaces of gas turbine engine turbomachinery and space propulsion components. The high-temperature, high-frequency loading environment seen by these components lead to severe stress gradients at the edge-of-contact. These contact stresses drive crack nucleation and propagation in fretting and are very sensitive to the geometry of the contacting bodies, the contact loads, materials, temperature, and contact surface tribology (friction). To diagnose the threat that small and relatively undetectable fretting cracks pose to damage tolerance and structural integrity of in-service components, the objective of this work is to develop a well-characterized experimental fretting rig capable of investigating fretting behavior of advanced aerospace alloys subjected to load and temperature conditions representative of such turbomachinery components.

  18. High temperature NASP engine seal development

    NASA Astrophysics Data System (ADS)

    This video details research being conducted at the Lewis Research Center on high temperature engine seal design for the National Aerospace Plane. To maximize the speed, the jets on the NASP extract oxygen from the air rather than carry large liquid fuel tanks; this creates temperatures within the jet of over 5000 F. To prevent these potentially explosive gases from escaping, researchers are developing new technologies for use in the engine seals. Two examples explained are the ceramic wafer seal and the braided ceramic rope seal. Computer simulations and laboratory footage are used to illustrate the workings of these seals. Benefits for other aerospace and industrial applications, as well as for the space shuttle, are explored.

  19. Creep resistant high temperature martensitic steel

    SciTech Connect

    Hawk, Jeffrey A.; Jablonski, Paul D.; Cowen, Christopher J.

    2015-11-13

    The disclosure provides a creep resistant alloy having an overall composition comprised of iron, chromium, molybdenum, carbon, manganese, silicon, nickel, vanadium, niobium, nitrogen, tungsten, cobalt, tantalum, boron, and potentially additional elements. In an embodiment, the creep resistant alloy has a molybdenum equivalent Mo(eq) from 1.475 to 1.700 wt. % and a quantity (C+N) from 0.145 to 0.205. The overall composition ameliorates sources of microstructural instability such as coarsening of M.sub.23C.sub.6 carbides and MX precipitates, and mitigates or eliminates Laves and Z-phase formation. A creep resistant martensitic steel may be fabricated by preparing a melt comprised of the overall composition followed by at least austenizing and tempering. The creep resistant alloy exhibits improved high-temperature creep strength in the temperature environment of around 650.degree. C.

  20. High Temperature Battery for Drilling Applications

    SciTech Connect

    Josip Caja

    2009-12-31

    In this project rechargeable cells based on the high temperature electrochemical system Na/beta''-alumina/S(IV) in AlCl3/NaCl were developed for application as an autonomous power source in oil/gas deep drilling wells. The cells operate in the temperature range from 150 C to 250 C. A prototype DD size cell was designed and built based on the results of finite element analysis and vibration testing. The cell consisted of stainless steel case serving as anode compartment with cathode compartment installed in it and a seal closing the cell. Critical element in cell design and fabrication was hermetically sealing the cell. The seal had to be leak tight, thermally and vibration stable and compatible with electrode materials. Cathode compartment was built of beta''-alumina tube which served as an electrolyte, separator and cathode compartment.