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Sample records for alamos gas shock

  1. Shock and Detonation Physics at Los Alamos National Laboratory

    SciTech Connect

    Robbins, David L; Dattelbaum, Dana M; Sheffield, Steve A

    2012-08-22

    WX-9 serves the Laboratory and the Nation by delivering quality technical results, serving customers that include the Nuclear Weapons Program (DOE/NNSA), the Department of Defense, the Department of Homeland Security and other government agencies. The scientific expertise of the group encompasses equations-of-state, shock compression science, phase transformations, detonation physics including explosives initiation, detonation propagation, and reaction rates, spectroscopic methods and velocimetry, and detonation and equation-of-state theory. We are also internationally-recognized in ultra-fast laser shock methods and associated diagnostics, and are active in the area of ultra-sensitive explosives detection. The facility capital enabling the group to fulfill its missions include a number of laser systems, both for laser-driven shocks, and spectroscopic analysis, high pressure gas-driven guns and powder guns for high velocity plate impact experiments, explosively-driven techniques, static high pressure devices including diamond anvil cells and dilatometers coupled with spectroscopic probes, and machine shops and target fabrication facilities.

  2. Fabrication of Optical Fiber Mechanical Shock Sensors for the Los Alamos HERT (High Explosive Radio Telemetry) Project

    SciTech Connect

    P. E. Klingsporn

    2005-11-14

    This document lists the requirements for the fiber optic mechanical shock sensor for the Los Alamos HERT (High Explosive Radio Telemetry) project and provides detailed process steps for fabricating, testing, and assembling the fiber shock sensors for delivery to Los Alamos.

  3. Single-interface Richtmyer-Meshkov turbulent mixing at the Los Alamos Vertical Shock Tube

    DOE PAGES

    Wilson, Brandon Merrill; Mejia Alvarez, Ricardo; Prestridge, Katherine Philomena

    2016-04-12

    We studied Mach number and initial conditions effects on Richtmyer–Meshkov (RM) mixing by the vertical shock tube (VST) at Los Alamos National Laboratory (LANL). At the VST, a perturbed stable light-to-heavy (air–SF6, A=0.64) interface is impulsively accelerated with a shock wave to induce RM mixing. We investigate changes to both large and small scales of mixing caused by changing the incident Mach number (Ma=1.3 and 1.45) and the three-dimensional (3D) perturbations on the interface. Simultaneous density (quantitative planar laser-induced fluorescence (PLIF)) and velocity (particle image velocimetry (PIV)) measurements are used to characterize preshock initial conditions and the dynamic shocked interface.more » Initial conditions and fluid properties are characterized before shock. Using two types of dynamic measurements, time series (N=5 realizations at ten locations) and statistics (N=100 realizations at a single location) of the density and velocity fields, we calculate several mixing quantities. Mix width, density-specific volume correlations, density–vorticity correlations, vorticity, enstrophy, strain, and instantaneous dissipation rate are examined at one downstream location. Results indicate that large-scale mixing, such as the mix width, is strongly dependent on Mach number, whereas small scales are strongly influenced by initial conditions. Lastly, the enstrophy and strain show focused mixing activity in the spike regions.« less

  4. Shock waves in a dilute granular gas

    NASA Astrophysics Data System (ADS)

    Reddy, M. H. Lakshminarayana; Ansumali, Santosh; Alam, Meheboob

    2014-12-01

    We study the evolution of shock waves in a dilute granular gas which is modelled using three variants of hydrodynamic equations: Euler, 10-moment and 14-moment models. The one-dimensional shock-wave problem is formulated and the resulting equations are solved numerically using a relaxation-type scheme. Focusing on the specific case of blast waves, the results on the density, the granular temperature, the skew temperature, the heat flux and the fourth moment are compared among three models. We find that the shock profiles are smoother for the 14-moment model compared to those predicted by the standard Euler equations. A shock-splitting phenomenon is observed in the skew granular temperature profiles for a blast wave.

  5. Compressible gas properties of UF/sub 6/ for isentropic, normal shock, and oblique shock conditions

    SciTech Connect

    Harloff, G.J.

    1984-11-01

    Isentropic, normal shock, and oblique shock tables are given for the real gas UF/sub 6/ for Mach numbers up to 22. An evaluation of the real gas effects is given. A computer program listing is included.

  6. Verification of 2-D Detonation Shock Dynamics in conjunction with Los Alamos Lagrangian hydrocode

    SciTech Connect

    Aida, Toru; Walter, John W.; Aslam, Tariq D.; Short, Mark

    2013-01-29

    As the latest version of the fast-tube Detonation Shock Dynamics (DSD) solver is linked with the Los Alamos Lagrangian hydrocode, verification problems from a 2006 DSD report (LA-14277 [1]) have been duplicated with some of the verification criteria changed to more quantitative ones. The observed error convergence is as good as or better than reported in [1], quite possibly due to the careful treatment of floating point numbers to ensure that their precision level is maintained throughout the code. This report duplicates the three sample verification problems in LA-14277 [1] using the Los Alamos ASC Lagrangian hydrocode (FLAG), official release of 3.2 Alpha6 with a few modifications. This version of FLAG is linked with the latest fast-tube Detonation Shock Dynamics (DSD) version beta 2 solver released in 2011 as part of the LanlDSD software product [2]. New verification criteria are used for the arcwave problem where two specific locations are chosen for burn arrival time comparison. For this report FLAG's internal driver code prepares the distance function ({Psi}) and material ID fields from its hydro setup, instead of the stand-alone driver that is being utilized by the other LANL hydrocodes currently interfaced to LanlDSD. As it is implemented in version 3.2 Alpha6, the {Psi} and material ID fields and other parameters are passed from FLAG to the DSD solver directly, and the burn table is directly passed back to FLAG as part of the calling arguments. The burn-front arrival time 'exact' solutions, mentioned in the sequel for the rate-stick and 'arc-wave' problems, are computed using a pair of special-purpose Fortran codes provided by Aslam [3]. In each case an ansatz for the form of the solution is made in which the radius from the detonator center point is used as the independent space coordinate. This leads to a simplified, problem-specific, 1D form of the governing equation. This equation is solved using 2nd-order spatial differencing and the forward Euler

  7. Fiber Bragg grating sensing of detonation and shock experiments at Los Alamos National Laboratory

    NASA Astrophysics Data System (ADS)

    Rodriguez, G.; Sandberg, R. L.; Jackson, S. I.; Dattelbaum, D. M.; Vincent, S. W.; McCulloch, Q.; Martinez, R. M.; Gilbertson, S. M.; Udd, E.

    2013-05-01

    An all optical-fiber-based approach to measuring high explosive detonation front position and velocity is described. By measuring total light return using an incoherent light source reflected from a fiber Bragg grating sensor in contact with the explosive, dynamic mapping of the detonation front position and velocity versus time is obtained. We demonstrate two calibration procedures and provide several examples of detonation front measurements: PBX 9502 cylindrical rate stick, radial detonation front in PBX 9501, and PBX 9501 detonation along a curved meridian line. In the cylindrical rate stick measurement, excellent agreement with complementary diagnostics (electrical pins and streak camera imaging) is achieved, demonstrating accuracy in the detonation front velocity to below the 0.3% level when compared to the results from the pin data. In a similar approach, we use embedded fiber grating sensors for dynamic pressure measurements to test the feasibility of these sensors for high pressure shock wave research in gas gun driven flyer plate impact experiments. By applying well-controlled steady shock wave pressure profiles to soft materials such as PMMA, we study the dynamic pressure response of embedded fiber Bragg gratings to extract pressure amplitude of the shock wave. Comparison of the fiber sensor results is then made with traditional methods (velocimetry and electro-magnetic particle velocity gauges) to gauge the accuracy of the approach.

  8. Dense gas shock tube: Design and analysis

    NASA Astrophysics Data System (ADS)

    Fergason, Stephen Harrison

    The study of BZT fluids in the single-phase vapor region is largely unexamined experimentally. To date, only one experimental study focused on nonclassical behavior in the single-phase vapor region. A new experimental program is proposed to examine the possibility of generating nonclassical behaviors in a shock tube apparatus. A design methodology is developed to identify the most important experimental characteristics and provide appropriate analytical and computational tools for subsequent study. Analysis suggests initial conditions, viscous effects, and wave interference as critical experimental characteristics. A shock tube design is proposed based on the results of the methodology. An algorithm is developed and applied to classical state equations to generate experimentally feasible initial conditions which maximize the possibility of detecting a single-phase rarefaction shock wave within experimental accuracy and precision. The algorithm was applied to a commercially available fluid thought to exhibit dense gas behavior. It was found that the range of possible initial conditions generating dense gas phenomena is larger than previously assumed. The shock tube is computationally modeled to validate the triple-discontinuity initial conditions and investigate the appropriate design dimensions. A two-step, flux-limited, total variation diminishing scheme was implemented to integrate the unsteady Navier-Stokes equations using three independent gas models. The triple-discontinuity flow field was verified with simulations. A novel shock tube was constructed based on the previous analysis. A sixteen-foot stainless steel pipe with a single diaphragm was placed within a series of electric ovens. The test section thermal environment was controlled utilizing sixteen independent PID control loops. Initial conditions similar in pressure and temperature to dense gas conditions were generated for nitrogen gas. The nitrogen test results were compared with classical one

  9. Equation of state measurements of shocked ammonia gas

    NASA Astrophysics Data System (ADS)

    Lang, John; Dattelbaum, Dana; Goodwin, Peter; Coe, Joshua; Garcia, Daniel

    2015-03-01

    Ammonia is one of the constituents of the fluid product mixture arising from explosives detonation. Few shock compression experiments have been performed on NH3 in either the gas or condensed phase. Earlier work by Dick (J. Chem. Phys. 74, 4053) and Mitchell, et al. (J. Chem. Phys. 76, 6273) examined the shock compressibility of liquid NH3. Nellis, et al. (Science 240, 781) also performed experiments on liquid mixtures of NH3 with water and isopropanol (a ``synthetic Uranus'') to develop an equation of state (EOS) for the outer planets. Here, we present the results from a series of gas gun-driven plate impact experiments on NH3 gas at elevated initial density. PDV and VISAR optical diagnostics were used to directly measure shock velocities and particle velocities in the shocked gas, used in quantifying the principal Hugoniot locus, and pressure and density of the shocked gas. Emission was measured using both 5-color pyrometry and streak spectroscopy, from which we estimated the temperature of the shocked gas. The pressure and density measurements were in good agreement with results from simulations using the SESAME EOS for NH3, however the measured temperatures were found to be consistently lower than in the simulations, and lower than shocked atomic gas species such as Ar.

  10. Shock interactions with a dense-gas wall layer

    SciTech Connect

    Kuhl, A.L.; Reichenbach, H.; Ferguson, R.E.

    1991-11-19

    Described here are experiments and calculations of the interaction of a planar shock with a dense-gas layer located on the floor of the shock tube test section. The shock front deposited vorticity in the layer by the baroclynic mechanism. The wall shear layer was unstable and rapidly evolved into a turbulent boundary layer with a wide spectrum of mixing scales. Density effects dominated the dynamics in the wall region.

  11. Radiative transfer effects on reflected shock waves. II - Absorbing gas.

    NASA Technical Reports Server (NTRS)

    Su, F. Y.; Olfe, D. B.

    1972-01-01

    Radiative cooling effects behind a reflected shock wave are calculated for an absorbing-emitting gas by means of an expansion procedure in the small density ratio across the shock front. For a gray gas shock layer with an optical thickness of order unity or less the absorption integral is simplified by use of the local temperature approximation, whereas for larger optical thicknesses a Rosseland diffusion type of solution is matched with the local temperature approximation solution. The calculations show that the shock wave will attenuate at first and then accelerate to a constant velocity. Under appropriate conditions the gas enthalpy near the wall may increase at intermediate times before ultimately decreasing to zero. A two-band absorption model yields end-wall radiant-heat fluxes which agree well with available shock-tube measurements.

  12. Shock wave processes in collisional gas particle mixtures

    NASA Astrophysics Data System (ADS)

    Khmel, T. A.; Fedorov, A. V.

    2016-06-01

    Structures and propagation of shock waves in high density particle suspensions in gas are investigated theoretically and numerically. A physical and mathematical model which takes into account integral collisions between the particles on the basis of molecular-kinetic approaches of theory of granular materials is applied. The possibility of different types of shock waves, including double front structures is revealed. The role of particle collisions in the dynamics of particle dense layer expansion under an influence of divergent shock wave and in processes of shock wave diffraction past a backward-facing step is analyzed.

  13. Density wave theory. [interstellar gas dynamics and galactic shock waves

    NASA Technical Reports Server (NTRS)

    Roberts, W. W., Jr.

    1977-01-01

    The prospect that density waves and galactic shock waves are present on the large scale in disk shaped galaxies has received support in recent years from both theoretical and observational studies. Large-scale galactic shock waves in the interstellar gas are suggested to play an important governing role in star formation, molecule formation, and the degree of development of spiral structure. Through the dynamics of the interstellar gas and the galactic shock-wave phenomenon, a new insight into the physical basis underlying the morphological classification system of galaxies is suggested.

  14. Experimental study of a shock accelerated thin gas layer

    SciTech Connect

    Jacobs, J.W.; Jenkins, D.G.; Klein, D.L.; Benjamin, R.F.

    1993-08-01

    Planar laser-induced fluorescence imaging is utilized in shock-tube experiments to visualize the development of a shock-accelerated thin gas layer. The Richtmyer-Meshkov instability of both sides of the heavy gas layer causes perturbations initially imposed on the two interfaces to develop into one of three distinct flow patterns. Two of the patterns exhibit vortex pairs which travel either upstream or downstream in the shock tube, while the third is a sinuous pattern that shows no vortex development until late in its evolution. The development of the observed patterns as well as the growth in the layer thickness is modeled by considering the dynamics of vorticity deposited in the layer by the shock interaction process. This model yields an expression for the layer growth which is in good agreement with measurements.

  15. Driver gas flow with fluctuations. [shock tube turbulent bursts

    NASA Technical Reports Server (NTRS)

    Johnson, J. A., III; Jones, W. R.; Santiago, J.

    1980-01-01

    A shock tube's driver gas can apparently provide flow with turbulent bursts. The fluctuations are interpreted using a boundary layer model of contact surface flow and results form a kinetic theory of turbulence. With this, a lower limit of 4 on the ratio of maximum to minimum turbulent intensities in contact surface instabilities has been estimated.

  16. Gas turbine power plant with supersonic shock compression ramps

    SciTech Connect

    Lawlor, Shawn P.; Novaresi, Mark A.; Cornelius, Charles C.

    2008-10-14

    A gas turbine engine. The engine is based on the use of a gas turbine driven rotor having a compression ramp traveling at a local supersonic inlet velocity (based on the combination of inlet gas velocity and tangential speed of the ramp) which compresses inlet gas against a stationary sidewall. The supersonic compressor efficiently achieves high compression ratios while utilizing a compact, stabilized gasdynamic flow path. Operated at supersonic speeds, the inlet stabilizes an oblique/normal shock system in the gasdynamic flow path formed between the rim of the rotor, the strakes, and a stationary external housing. Part load efficiency is enhanced by use of a lean pre-mix system, a pre-swirl compressor, and a bypass stream to bleed a portion of the gas after passing through the pre-swirl compressor to the combustion gas outlet. Use of a stationary low NOx combustor provides excellent emissions results.

  17. Development of pulsed gas discharge lasers for shock hardening

    NASA Astrophysics Data System (ADS)

    Hintz, Gerd; Tkotz, R.; Keusch, C.; Negendanck, Matthias; Christiansen, Jens; Hoffmann, D. H. H.

    1996-08-01

    Shock hardening of metals (e.g. Ti, stainless steel) by pulsed lasers offers the possibility of large hardening depth (several millimeters) without serious damage to the surface of the workpiece. Previous investigations for shock hardening have mainly been performed with high power solid state lasers. The adaptation of commercial, high power gas discharge lasers to the shock hardening process could make this process relevant for industrial applications, as high repetition rates may be used. Two different laser systems have been investigated: a TEA carbon-dioxide laser and a XeCl laser. Both systems have pulse energies of some joule, a pulse length of several ten nanoseconds, and pulse repetition rates of up to 10 Hertz. The divergence of the beam was minimized to improve focusing properties. Systematic measurements of the laser induced pressure by means of piezo probes have been performed. An enhancement of the hardness of illuminated Ti(RT15) targets has been found and is reported.

  18. Dynamics of shock waves in a superfluid unitary Fermi gas

    NASA Astrophysics Data System (ADS)

    Wen, Wen; Shui, Tiankun; Shan, Yafei; Zhu, Changping

    2015-09-01

    We study the formation and dynamics of shock waves initiated by a repulsive potential in a superfluid unitary Fermi gas by using the order-parameter equation. In the theoretical framework, the regularization process of shock waves mediated by the quantum pressure term is purely dispersive. Our results show good agreement with the experiment of Joseph et al (2011 Phys. Rev. Lett. 106 150401). We reveal that the boxlike-shaped density peak observed in the experiment consists of many vortex rings due to the transverse instability of the dispersive shock wave. In addition, we study the transition from a sound wave to subsonic shock waves as the strength of the repulsive potential increases and show a strong qualitative change in the propagation speed of the wavefronts. For a relatively small strength of the repulsive potential, the propagation speed decreases below the sound speed with the increase of the strength as a scaling behavior. For a large strength where the shock waves are formed by colliding two spatially separated clouds, the speed is still smaller than the sound speed, but remains almost unchanged as the strength increases, which can be interpreted as the same expansion speed of the proliferation of the vortex rings originated from the transverse instability.

  19. A Radiative Instability in Post-shock-cooling Circumstellar Gas

    NASA Astrophysics Data System (ADS)

    Schirrmacher, V.; Woitke, P.; Sedlmayr, E.

    Investigations on non-LTE radiative heating and cooling processes behind shock waves in circumstellar environments have revealed the existence of a radiative/thermal instability in the post-shock cooling gas. The results have been obtained in the framework of spherical symmetric, hydrodynamical model calculations for dust-enshrouded circumstellar envelopes (CSEs) of Asymptotic Giant Branch (AGB) stars, which combine a time-dependent treatment of dust formation with grey radiative transfer and tabulated non-LTE state functions. The instability occurs in a situation, where thin and hot atomic gas behind a shock wave cools down to the molecular domain where it remains in pressure equilibrium with its environment. Radiative cooling in this case causes a temperature decrease and a density increase which both favour molecule formation. The molecules, in return, accelerate the radiative cooling. Thereby, a self-amplifying feedback loop is established, which in the model leads to the amplification of small density fluctuations in the post-shock cooling region to large density inhomogeneities of more than one order of magnitude. This radiative/thermal instability is not restricted to one spatial dimension (as in the model) and is possibly capable to generate a strongly non-homogeneous density distribution around pulsating stars, which can, for example lead to dust cloud formation. In this presentation, we discuss the parameter range for this instability as well as the underlying thermodynamical concept of the model calculations.

  20. Experimental investigation of a twice-shocked spherical gas inhomogeneity

    NASA Astrophysics Data System (ADS)

    Haehn, Nicholas; Weber, Chris; Oakley, Jason; Anderson, Mark; Bonazza, Riccardo

    2008-11-01

    Results are presented from a series of experiments and simulations studying the behavior of a spherical gas inhomogeneity impulsively accelerated by an incident and a reflected shock wave. Two Atwood numbers are studied using soap film to create argon and sulfur-hexafluoride bubbles impacted by a planar shock wave of strength M = 1.33. The experiments are performed in a 9.2-m-long vertical shock tube with a square internal cross-section, 25.4 cm per side. The bubbles are released from an injector that is pneumatically retracted into the side of the shock tube. For the scenario involving an Argon bubble free falling in ambient nitrogen (A = 0.176), the reshock occurs during the tail end of the bubble's compression regime after it has already shown slight growth and vortex core development. For the SF6 bubble free falling in ambient nitrogen (A = 0.681), the reshock occurs later in the bubble's developmental stage. The flow is visualized with planar Mie scattering and temporal evolutions are analyzed for the spatial dimensions, growth rates and vorticity estimates. PIV analysis is performed for several instances using the soap film as tracer particles. These trends are compared to simulations performed with the Eulerian AMR hydrodynamics code Raptor from LLNL.

  1. Observation of Shock Waves in a Strongly Interacting Fermi Gas

    SciTech Connect

    Joseph, J. A.; Thomas, J. E.; Kulkarni, M.; Abanov, A. G.

    2011-04-15

    We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a boxlike shape. We model the nonlinear dynamics of these collisions by using quasi-1D hydrodynamic equations. Our simulations of the time-dependent density profiles agree very well with the data and provide clear evidence of shock wave formation in this universal quantum hydrodynamic system.

  2. Observation of shock waves in a strongly interacting Fermi gas.

    PubMed

    Joseph, J A; Thomas, J E; Kulkarni, M; Abanov, A G

    2011-04-15

    We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a boxlike shape. We model the nonlinear dynamics of these collisions by using quasi-1D hydrodynamic equations. Our simulations of the time-dependent density profiles agree very well with the data and provide clear evidence of shock wave formation in this universal quantum hydrodynamic system.

  3. Experimental Plans for Subsystems of a Shock Wave Driven Gas Core Reactor

    NASA Technical Reports Server (NTRS)

    Kazeminezhad, F.; Anghai, S.

    2008-01-01

    This Contractor Report proposes a number of plans for experiments on subsystems of a shock wave driven pulsed magnetic induction gas core reactor (PMI-GCR, or PMD-GCR pulsed magnet driven gas core reactor). Computer models of shock generation and collision in a large-scale PMI-GCR shock tube have been performed. Based upon the simulation results a number of issues arose that can only be addressed adequately by capturing experimental data on high pressure (approx.1 atmosphere or greater) partial plasma shock wave effects in large bore shock tubes ( 10 cm radius). There are three main subsystems that are of immediate interest (for appraisal of the concept viability). These are (1) the shock generation in a high pressure gas using either a plasma thruster or pulsed high magnetic field, (2) collision of MHD or gas dynamic shocks, their interaction time, and collision pile-up region thickness, and (3) magnetic flux compression power generation (not included here).

  4. Shock

    MedlinePlus

    ... several kinds of shock. Hypovolemic shock happens when you lose a lot of blood or fluids. Causes include internal or external bleeding, dehydration, burns, and severe vomiting and/or diarrhea. Septic shock is caused by ...

  5. On one-dimensional planar and nonplanar shock waves in a relaxing gas

    NASA Astrophysics Data System (ADS)

    Sharma, V. D.; Radha, Ch.

    1994-06-01

    The paper examines the evolutionary behavior of shock waves of arbitrary strength propagating through a relaxing gas in a duct with spatially varying cross section. An infinite system of transport equations, governing the strength of a shock wave and the induced discontinuities behind it, are derived in order to study the kinematics of the shock front. The infinite system of transport equations, when subjected to a truncation approximation, provides an efficient system of only finite number of ordinary differential equations describing the shock propagation problem. The analysis, which accounts for the dynamical coupling between the shock fronts and the flow behind them, describes correctly the nonlinear steepening effects of the flow behind the shocks. Effects of relaxation on the evolutionary behavior of shocks are discussed. The first-order truncation approximation accurately describes the decay behavior of weak shocks; the usual decay laws for weak shocks in a nonrelaxing gas are exactly recovered. The results concerning shocks of arbitrary strength are compared with the characteristic rule. In the limit of vanishing shock strength, the transport equation for the first-order induced discontinuity leads to an exact description of an acceleration wave. In the strong shock limit, the second-order truncation criterion leads to a propagation law for imploding shocks which is in agreement (within 5% error) with the Guderley's exact similarity solution.

  6. Numerical simulation of transient inviscid gas flows in a shock tube

    NASA Technical Reports Server (NTRS)

    Yang, J. Y.; Lombard, C. K.; Nagaraj, N.; Bershader, D.

    1985-01-01

    Time-dependent upwind high resolution schemes for solving the Euler equations were developed and applied to simulate 1-D and 2-D transient inviscid gas flows in a shock tube. Using obstacles of different geometries, a series of calculations were carried out to investigate the transient complex shock-wave diffraction phenomena. Shock-wave and objects interactions with shock Mach-number Ms ranging from 2 to 20 were considered. Comparison with analytical and available experimental results indicate good agreement. Display of detailed flow structures including multiple Mach shocks, slip surfaces, and vortex are also given.

  7. Sub-shock formation in Grad 10-moment equations for a binary gas mixture

    NASA Astrophysics Data System (ADS)

    Bisi, Marzia; Conforto, Fiammetta; Martalò, Giorgio

    2016-09-01

    The shock structure problem for Grad 10-moment equations for an inert binary mixture is investigated: necessary conditions for the formation of sub-shocks in fields of only one gas or of both components are rigorously obtained, and a detailed comparison with the shock-wave structure of its principal sub-system (deduced assuming vanishing viscous stress tensors) and of the equilibrium Euler sub-system is performed. Some numerical simulations for a mixture of argon and helium are presented.

  8. Shock Structure Analysis and Aerodynamics in a Weakly Ionized Gas Flow

    NASA Technical Reports Server (NTRS)

    Saeks, R.; Popovic, S.; Chow, A. S.

    2006-01-01

    The structure of a shock wave propagating through a weakly ionized gas is analyzed using an electrofluid dynamics model composed of classical conservation laws and Gauss Law. A viscosity model is included to correctly model the spatial scale of the shock structure, and quasi-neutrality is not assumed. A detailed analysis of the structure of a shock wave propagating in a weakly ionized gas is presented, together with a discussion of the physics underlying the key features of the shock structure. A model for the flow behind a shock wave propagating through a weakly ionized gas is developed and used to analyze the effect of the ionization on the aerodynamics and performance of a two-dimensional hypersonic lifting body.

  9. Shock-acceleration of a pair of gas inhomogeneities

    NASA Astrophysics Data System (ADS)

    Navarro Nunez, Jose Alonso; Reese, Daniel; Oakley, Jason; Rothamer, David; Bonazza, Riccardo

    2014-11-01

    A shock wave moving through the interstellar medium distorts density inhomogeneities through the deposition of baroclinic vorticity. This process is modeled experimentally in a shock tube for a two-bubble interaction. A planar shock wave in nitrogen traverses two soap-film bubbles filled with argon. The two bubbles share an axis that is orthogonal to the shock wave and are separated from one another by a distance of approximately one bubble diameter. Atomization of the soap-film by the shock wave results in dispersal of droplets that are imaged using Mie scattering with a laser sheet through the bubble axis. Initial condition images of the bubbles in free-fall (no holder) are taken using a high-speed camera and then two post-shock images are obtained with two laser pulses and two cameras. The first post-shock image is of the early time compression stage when the sphere has become ellipsoidal, and the second image shows the emergence of vortex rings which have evolved due to vorticity depostion by the shock wave. Bubble morphology is characterized with length scale measurements.

  10. Analytical solution of the problem of a shock wave in the collapsing gas in Lagrangian coordinates

    NASA Astrophysics Data System (ADS)

    Kuropatenko, V. F.; Shestakovskaya, E. S.

    2016-10-01

    It is proposed the exact solution of the problem of a convergent shock wave and gas dynamic compression in a spherical vessel with an impermeable wall in Lagrangian coordinates. At the initial time the speed of cold ideal gas is equal to zero, and a negative velocity is set on boundary of the sphere. When t > t0 the shock wave spreads from this point into the gas. The boundary of the sphere will move under the certain law correlated with the motion of the shock wave. The trajectories of the gas particles in Lagrangian coordinates are straight lines. The equations determining the structure of the gas flow between the shock front and gas border have been found as a function of time and Lagrangian coordinate. The dependence of the entropy on the velocity of the shock wave has been found too. For Lagrangian coordinates the problem is first solved. It is fundamentally different from previously known formulations of the problem of the self-convergence of the self-similar shock wave to the center of symmetry and its reflection from the center, which was built up for the infinite area in Euler coordinates.

  11. A new class of exact solutions with shock waves in gas dynamics

    NASA Astrophysics Data System (ADS)

    Poslavskii, S. A.

    1985-10-01

    New exact solutions are obtained for one-dimensional gasdynamic equations with strong shock waves propagating in a moving medium, with gas flow behind the shock wave described by a solution with uniform deformation. Solutions are then presented for a problem concerning explosion without counterpressure in a uniformly expanding (contracting) gas with an arbitrary adiabatic exponent and a nonuniform initial density distribution. A solution is also presented for the problem of cavity collapse in a dust cloud with the formation of a shock wave.

  12. Quantification of initial-data uncertainty on a shock-accelerated gas cylinder

    SciTech Connect

    Tritschler, V. K. Avdonin, A.; Hickel, S.; Hu, X. Y.; Adams, N. A.

    2014-02-15

    We quantify initial-data uncertainties on a shock accelerated heavy-gas cylinder by two-dimensional well-resolved direct numerical simulations. A high-resolution compressible multicomponent flow simulation model is coupled with a polynomial chaos expansion to propagate the initial-data uncertainties to the output quantities of interest. The initial flow configuration follows previous experimental and numerical works of the shock accelerated heavy-gas cylinder. We investigate three main initial-data uncertainties, (i) shock Mach number, (ii) contamination of SF{sub 6} with acetone, and (iii) initial deviations of the heavy-gas region from a perfect cylindrical shape. The impact of initial-data uncertainties on the mixing process is examined. The results suggest that the mixing process is highly sensitive to input variations of shock Mach number and acetone contamination. Additionally, our results indicate that the measured shock Mach number in the experiment of Tomkins et al. [“An experimental investigation of mixing mechanisms in shock-accelerated flow,” J. Fluid. Mech. 611, 131 (2008)] and the estimated contamination of the SF{sub 6} region with acetone [S. K. Shankar, S. Kawai, and S. K. Lele, “Two-dimensional viscous flow simulation of a shock accelerated heavy gas cylinder,” Phys. Fluids 23, 024102 (2011)] exhibit deviations from those that lead to best agreement between our simulations and the experiment in terms of overall flow evolution.

  13. Hypersonic Viscous Shock Layer of Nonequilibrium Dissociating Gas

    NASA Technical Reports Server (NTRS)

    Chung, Paul M.

    1961-01-01

    The nonequilibrium chemical reaction of dissociation and recombination is studied theoretically for air in the viscous shock layer at the stagnation region af axisymmetric bodies. The flight regime considered is for speeds near satellite speed and for altitudes between 200,000 and 300,000 feet. The convective heat transfer to noncatalytic walls is obtained. The effects of nose radius, wall temperature, and flight altitude on the chemical state of the shock layer are studied. An analysis is also made on the simultaneous effect of nonequilibrium chemical reaction and air rarefaction on the shock layer thickness.

  14. ALEGRA Validation Studies for Regular, Mach, and Double Mach Shock Reflection in Gas Dynamics

    SciTech Connect

    CHEN, MARY I.; TRUCANO, TIMOTHY G.

    2002-09-01

    In this report we describe the performance of the ALEGRA shock wave physics code on a set of gas dynamic shock reflection problems that have associated experimental pressure data. These reflections cover three distinct regimes of oblique shock reflection in gas dynamics--regular, Mach, and double Mach reflection. For the selected data, the use of an ideal gas equation of state is appropriate, thus simplifying to a considerable degree the task of validating the shock wave computational capability of ALEGRA in the application regime of the experiments. We find good agreement of ALEGRA with reported experimental data for sufficient grid resolution. We discuss the experimental data, the nature and results of the corresponding ALEGRA calculations, and the implications of the presented experiment--calculation comparisons.

  15. Shock velocity increase due to a heterogeneity produced by a two-gas layer.

    PubMed

    Elbaz, Déborah; Jourdan, Georges; Houas, Lazhar; Jaouen, Stéphane; Ballereau, Philippe; Dias, Frédéric; Canaud, Benoit

    2012-06-01

    Shock tube experiments are performed in order to study shock propagation along a two-gas layer in a confined geometry and to compare it to the case of a homogeneous density equivalent mixture. The analysis of the homogeneous case gives values for the adiabatic coefficient and density of the mixture of both gases, while the comparison between heterogeneous and homogeneous media with the same averaged density shows modifications of the shock front shape and velocity. In the two-gas layer, the shock propagates faster than in the homogeneous medium. The shock front is curved with a triple point which appears close to the shock-tube wall, in the slow medium, while it stays planar during its whole propagation in the homogeneous mixture. A correlation is found between the angle of curvature and the shock velocity increase. It is confirmed by two-dimensional Eulerian numerical calculations. Experiments and calculations exhibit very good agreement on all the measurements when molecular diffusion is taken into account in the numerical calculations. A sustained irregular refraction pattern of the shock front at the diffuse interface of both gases is obtained experimentally and confirmed by the calculations.

  16. On imploding cylindrical and spherical shock waves in a perfect gas

    NASA Astrophysics Data System (ADS)

    Ponchaut, N. F.; Hornung, H. G.; Pullin, D. I.; Mouton, C. A.

    2006-08-01

    The problem of a cylindrically or spherically imploding and reflecting shock wave in a flow initially at rest is studied without the use of the strong-shock approximation. Dimensional arguments are first used to show that this flow admits a general solution where an infinitesimally weak shock from infinity strengthens as it converges towards the origin. For a perfect-gas equation of state, this solution depends only on the dimensionality of the flow and on the ratio of specific heats. The Guderley power-law result can then be interpreted as the leading-order, strong-shock approximation, valid near the origin at the implosion centre. We improve the Guderley solution by adding two further terms in the series expansion solution for both the incoming and the reflected shock waves. A series expansion, valid where the shock is still weak and very far from the origin, is also constructed. With an appropriate change of variables and using the exact shock-jump conditions, a numerical, characteristics-based solution is obtained describing the general shock motion from almost infinity to very close to the reflection point. Comparisons are made between the series expansions, the characteristics solution, and the results obtained using an Euler solver. These show that the addition of two terms to the Guderley solution significantly extends the range of validity of the strong-shock series expansion.

  17. When galaxy clusters collide: the impact of merger shocks on cluster gas and galaxy evolution

    NASA Astrophysics Data System (ADS)

    Stroe, A.

    2015-09-01

    Galaxy clusters mainly grow through mergers with other clusters and groups. Major mergers give rise to cluster-wide traveling shocks, which can be detected at radio wavelengths as relics: elongated, diffuse synchrotron emitting areas located at the periphery of merging clusters. The 'Sausage' cluster hosts an extraordinary Mpc-wide relic, which enables us to study to study particle acceleration and the effects of shocks on cluster galaxies. We derive shock properties and the magnetic field structure for the relic. Our results indicate that particles are shock-accelerated, but turbulent re-acceleration or unusually efficient transport of particles in the downstream area are important effects. We demonstrate the feasibility of high-frequency observations of radio relics, by presenting a 16 GHz detection of the 'Sausage' relic. Halpha mapping of the cluster provides the first direct test as to whether the shock drives or prohibits star formation. We find numerous galaxies in! close proximity to the radio relic which are extremely massive, metal-rich, star-forming with evidence for gas mass loss though outflows. We speculate that the complex interaction between the merger, the shock wave and gas is a fundamental driver in the evolution of cluster galaxies from gas rich spirals to gas-poor ellipticals.

  18. Prediction of Shock Wave Structure in Weakly Ionized Gas Flow by Solving MGD Equation

    NASA Technical Reports Server (NTRS)

    Deng, Z. T.; Oviedo-Rojas, Ruben; Chow, Alan; Litchford, Ron J.; Cook, Stephen (Technical Monitor)

    2002-01-01

    This paper reports the recent research results of shockwave structure predictions using a new developed code. The modified Rankine-Hugoniot relations across a standing normal shock wave are discussed and adopted to obtain jump conditions. Coupling a electrostatic body force to the Burnett equations, the weakly ionized flow field across the shock wave was solved. Results indicated that the Modified Rankine-Hugoniot equations for shock wave are valid for a wide range of ionization fraction. However, this model breaks down with small free stream Mach number and with large ionization fraction. The jump conditions also depend on the value of free stream pressure, temperature and density. The computed shock wave structure with ionization provides results, which indicated that shock wave strength may be reduced by existence of weakly ionized gas.

  19. Dispersive and classical shock waves in Bose-Einstein condensates and gas dynamics

    SciTech Connect

    Hoefer, M. A.; Ablowitz, M. J.; Coddington, I.; Cornell, E. A.; Engels, P.; Schweikhard, V.

    2006-08-15

    A Bose-Einstein condensate (BEC) is a quantum fluid that gives rise to interesting shock-wave nonlinear dynamics. Experiments depict a BEC that exhibits behavior similar to that of a shock wave in a compressible gas, e.g., traveling fronts with steep gradients. However, the governing Gross-Pitaevskii (GP) equation that describes the mean field of a BEC admits no dissipation, hence classical dissipative shock solutions do not explain the phenomena. Instead, wave dynamics with small dispersion is considered and it is shown that this provides a mechanism for the generation of a dispersive shock wave (DSW). Computations with the GP equation are compared to experiment with excellent agreement. A comparison between a canonical one-dimensional (1D) dissipative and dispersive shock problem shows significant differences in shock structure and shock-front speed. Numerical results associated with the three-dimensional experiment show that three- and two-dimensional approximations are in excellent agreement and 1D approximations are in good qualitative agreement. Using 1D DSW theory, it is argued that the experimentally observed blast waves may be viewed as dispersive shock waves.

  20. Mapping of Shocked Molecular Gas in the Supernova Remnant W44

    NASA Astrophysics Data System (ADS)

    Mitchell, G. F.; Frail, D. A.

    2002-06-01

    The supernova remnant W44 is expanding into dense molecular gas. We earlier obtained a small (80”x80”) map of CO emission from W44 and found a spatial correlation between CO line emission and centimeter wave synchrotron continuum emission (Frail and Mitchell 1998). To explore this surprising correlation further, we have obtained larger maps of W44 in the CO J=3-2 transition. One map is 6x12 arcminutes in size and encompasses the OH (1720 MHz) masers D, E, and F (in the notation of Claussen et al. 1997). The other CO map is 3x6 arcminutes in size and includes the OH masers B and C. The CO maps have a resolution of 13 arcseconds. Broad CO lines (30 to 50 km/s), indicative of shocked gas, are present in both maps. The shocked molecular gas takes the form of clumpy arcs and extended filaments. A comparison between the shocked CO and a 1442 MHz continuum map of comparable resolution (Claussen et al. 1997) shows the following: (1) Some of the shocked CO features coincide with features in the continuum map. (2) Other CO-emitting features do not show corresponding continuum emission. (3) Some bright continuum arcs have no associated molecular emission. The observed coincidences between molecular and synchrotron emission are surprising because models of supernova shocks in a molecular cloud (e.g. Bykov et al. 2000) predict that the synhrotron emitting arcs are radiative shells formed in the interclump, atomic, gas.

  1. Gas-grain energy transfer in solar nebula shock waves: Implications for the origin of chondrules

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Horanyi, M.

    1993-01-01

    Meteoritic chondrules provide evidence for the occurrence of rapid transient heating events in the protoplanetary nebula. Astronomical evidence suggests that gas dynamic shock waves are likely to be excited in protostellar accretion disks by processes such as protosolar mass ejections, nonaxisymmetric structures in an evolving disk, and impact on the nebula surface of infalling 'clumps' of circumstellar gas. Previous detailed calculations of gas-grain energy and momentum transfer have supported the possibility that such shock waves could have melted pre-existing chondrule-sized grains. The main requirement for grains to reach melting temperatures in shock waves with plausibly low Mach numbers is that grains existed in dust-rich zones (optical depth greater than 1) where radiative cooling of a given grain can be nearly balanced by radiation from surrounding grains. Localized dust-rich zones also provide a means of explaining the apparent small spatial scale of heating events. For example, the scale size of at least some optically thick dust-rich zones must have been relatively small (less than 10 kilometers) to be consistent with petrologic evidence for accretion of hot material onto cold chondrules. The implied number density of mm-sized grains for these zones would be greater than 30 m(exp -3). In this paper, we make several improvements of our earlier calculations to include radiation self-consistently in the shock jump conditions, and we include heating of grains due to radiation from the shocked gas. In addition, we estimate the importance of momentum feedback of dust concentrations onto the shocked gas which would tend to reduce the efficiency of gas dynamic heating of grains in the center of the dust cloud.

  2. Hydrodynamic Simulations of Gaseous Argon Shock Experiments

    NASA Astrophysics Data System (ADS)

    Garcia, Daniel; Dattelbaum, Dana; Goodwin, Peter; Morris, John; Sheffield, Stephen; Burkett, Michael

    2015-06-01

    The lack of published Argon gas shock data motivated an evaluation of the Argon Equation of State (EOS) in gas phase initial density regimes never before reached. In particular, these regimes include initial pressures in the range of 200-500 psi (0.025 - 0.056 g/cc) and initial shock velocities around 0.2 cm/ μs. The objective of the numerical evaluation was to develop a physical understanding of the EOS behavior of shocked and subsequently multiply re-shocked Argon gas initially pressurized to 200-500 psi through Pagosa numerical hydrodynamic simulations utilizing the SESAME equation of state. Pagosa is a Los Alamos National Laboratory 2-D and 3-D Eulerian hydrocode capable of modeling high velocity compressible flow with multiple materials. The approach involved the use of gas gun experiments to evaluate the shock and multiple re-shock behavior of pressurized Argon gas to validate Pagosa simulations and the SESAME EOS. Additionally, the diagnostic capability within the experiments allowed for the EOS to be fully constrained with measured shock velocity, particle velocity and temperature. The simulations demonstrate excellent agreement with the experiments in the shock velocity/particle velocity space, but note unanticipated differences in the ionization front temperatures.

  3. Shocked Molecular Gas in the SNR 3C391

    NASA Astrophysics Data System (ADS)

    Bock, D. C.-J.; Wright, M. C. H.; Frail, D. A.; Gaensler, B. M.; Wilner, D. J.

    1999-05-01

    The discovery of OH (1720 MHz) masers in supernova remnants (SNRs) provides us with a convenient method for identifying promising candidates for studies of SNR/molecular cloud interactions. One remnant which is an ideal subject is 3C391. Here, single dish observations reveal a myriad of molecular lines from a giant shocked cloud at the blast-wave of the remnant. We present recent millimeter-wave observations of 3C391 with the Berkeley-Illinois-Maryland Association (BIMA) array. We have imaged the region towards the OH maser in HCN (J=1--0) and HCO+ (J=1--0) at a resolution of 4 arcsec. The morphology and brightness of the emission in HCO+ and HCN are similar; we resolve the shocked cloud seen by Frail and Mitchell (1998) into several clumps of characteristic size 10 arcsec. The maser is midway between two of these clumps, rather than being coincident with the peak column density. The clumps all have similar spectra with line-widths of ~ 30 km s(-1) , although there is evidence for a velocity gradient between the clumps. We examine the physical conditions of the shocked environment and discuss the relative abundances of the molecules. A companion study of the interaction between the SNR W51C and an associated molecular cloud is underway.

  4. Effect of temperature shock and inventory surprises on natural gas and heating oil futures returns.

    PubMed

    Hu, John Wei-Shan; Hu, Yi-Chung; Lin, Chien-Yu

    2014-01-01

    The aim of this paper is to examine the impact of temperature shock on both near-month and far-month natural gas and heating oil futures returns by extending the weather and storage models of the previous study. Several notable findings from the empirical studies are presented. First, the expected temperature shock significantly and positively affects both the near-month and far-month natural gas and heating oil futures returns. Next, significant temperature shock has effect on both the conditional mean and volatility of natural gas and heating oil prices. The results indicate that expected inventory surprises significantly and negatively affects the far-month natural gas futures returns. Moreover, volatility of natural gas futures returns is higher on Thursdays and that of near-month heating oil futures returns is higher on Wednesdays than other days. Finally, it is found that storage announcement for natural gas significantly affects near-month and far-month natural gas futures returns. Furthermore, both natural gas and heating oil futures returns are affected more by the weighted average temperature reported by multiple weather reporting stations than that reported by a single weather reporting station.

  5. Experimental study on a heavy-gas cylinder accelerated by cylindrical converging shock waves

    NASA Astrophysics Data System (ADS)

    Si, T.; Zhai, Z.; Luo, X.; Yang, J.

    2014-01-01

    The Richtmyer-Meshkov instability behavior of a heavy-gas cylinder accelerated by a cylindrical converging shock wave is studied experimentally. A curved wall profile is well-designed based on the shock dynamics theory [Phys. Fluids, 22: 041701 (2010)] with an incident planar shock Mach number of 1.2 and a converging angle of in a mm square cross-section shock tube. The cylinder mixed with the glycol droplets flows vertically through the test section and is illuminated horizontally by a laser sheet. The images obtained only one per run by an ICCD (intensified charge coupled device) combined with a pulsed Nd:YAG laser are first presented and the complete evolution process of the cylinder is then captured in a single test shot by a high-speed video camera combined with a high-power continuous laser. In this way, both the developments of the first counter-rotating vortex pair and the second counter-rotating vortex pair with an opposite rotating direction from the first one are observed. The experimental results indicate that the phenomena induced by the converging shock wave and the reflected shock formed from the center of convergence are distinct from those found in the planar shock case.

  6. H I ZEEMAN EXPERIMENTS OF SHOCKED ATOMIC GAS IN TWO SUPERNOVA REMNANTS INTERACTING WITH MOLECULAR CLOUDS

    SciTech Connect

    Koo, Bon-Chul; Heiles, Carl; Stanimirovic, Snezana; Troland, Tom

    2010-07-15

    We have carried out observations of Zeeman splitting of the H I 21 cm emission line from shocked atomic gas in the supernova remnants (SNRs) IC 443 and W51C using the Arecibo telescope. The observed shocked atomic gas is expanding at {approx}100 km s{sup -1} and this is the first Zeeman experiment of such fast-moving, shocked atomic gas. The emission lines, however, are very broad and the systematic error due to baseline curvature hampers an accurate measurement of field strengths. We derive an upper limit of 100-150 {mu}G on the strength of the line-of-sight field component. These two SNRs are interacting with molecular clouds, but the derived upper limits are considerably smaller than the field strengths expected from a strongly shocked dense cloud. We discuss the implications and conclude that either the magnetic field within the telescope beam is mostly randomly oriented or the high-velocity H I emission is from a shocked interclump medium of relatively low density.

  7. Numerical Studies of the Application of Shock Tube Technology for Cold Gas Dynamic Spray Process

    NASA Astrophysics Data System (ADS)

    Nickel, R.; Bobzin, K.; Lugscheider, E.; Parkot, D.; Varava, W.; Olivier, H.; Luo, X.

    2007-12-01

    A new method for a combustion-free spraying is studied fundamentally by modeling and simulation in comparison with first experiments. The article focuses on the numerical simulation of the gas-particle nozzle flow, which is generated by the shock reflection at the end wall section of a shock tube. To study the physical fundamentals of this process, at present only a single shot operation is considered. The particles are injected downstream of the nozzle throat into a supersonic nozzle flow. The measurements of the particle velocity made by a laser Doppler anemometry (LDA) set up show that the maximum velocity amounts to 1220 m/s for stainless steel particles of 15 μm diameter. The CFD-Code (Fluent) is first verified by a comparison with available numerical and experimental data for gas and gas-particle flow fields in a long Laval-nozzle. The good agreement implied the great potential of the new dynamic process concept for cold-gas coating applications. Then the flow fields in the short Laval nozzle designed and realized by the Shock Wave Laboratory (SWL) are investigated. The gas flow for experimentally obtained stagnation conditions is simulated. The gas-particle flow without and with the influence of the particles on the gas flow is calculated by the Surface Engineering Institute (IOT) and compared with experiments. The influence of the injection parameters on the particle velocities is investigated, as well.

  8. Shock Waves in the BEC to BCS Crossover of a Fermi Gas

    NASA Astrophysics Data System (ADS)

    Baird, Lorin; Joseph, James; Thomas, John

    2016-05-01

    We observe shock waves in a Fermi gas near a Feshbach resonance, using a micro-mirror array to create a spatially controlled, blue-detuned, repulsive optical potential. We separate an optically-trapped gas of 6 Li into two clouds with steep density profiles. When the repulsive potential beam is extinguished, the two halves of the cloud collide in the optical trap, producing shock waves. Using in-situ imaging, we find that the steep density gradients associated with shockwaves are most pronounced near resonance and become less pronounced as the magnetic field is tuned above resonance to create a weakly interacting Fermi gas or below resonance to create a weakly interacting Bose gas of dimers. Using this method, we study the crossover from dispersive to dissipative non-linear hydrodynamics as a function of interaction strength and temperature. Funding by: NSF, DOE, ARO, and AFOSR.

  9. Effect of internal gas pressure on the shock consolidation of 304 stainless steel powders

    SciTech Connect

    Elliott, N.E.; Staudhammer, K.P.

    1990-01-01

    Capsules of 304 SS powders having a pre-compacted density of 67% were shock consolidated at peak pressures of 100 GPa. Initial internal N{sub 2} gas pressures from 7 {times} 10 {sup {minus}4} Pa to 0.1 Gpa were employed. However, as the internal N{sub 2} gas pressure in the powders was increased, the quality of the compacted density decreased. While it is intuitive that high internal gas pressures in porous materials do not enhance their consolidation, a greater understanding of the consolidation process and the part entrapped (intentional or unintentional) gas plays is elucidated. 12 refs., 9 figs.

  10. Richtmyer-Meshkov instability at a gas interface accelerated by a Mach 3 shock wave

    NASA Astrophysics Data System (ADS)

    Anderson, Mark; Oakley, Jason; Motl, Bradley; Ranjan, Devesh; Bonazza, Riccardo; Greenough, Jeff

    2003-11-01

    An interface between gases with different acoustic impedance is prepared inside a vertical shock tube with square internal cross section using either of two approaches. In one case, a sinusoidally-shaped thin copper plate, initially separating a heavy from a light gas (with the light gas below the plate) is retracted from the shock tube; the Rayleigh-Taylor (RT) instability drives the subsequent fluid motion, causing the amplitude of the sinusoidal perturbation at the gas interface to grow. In this case, the interface exhibits a dominant 2-D perturbation, with 3-D side effects due to the vortex shedding in the plate's wake and their own RT growth. In the other approach, a discontinous interface is created with a soap film incapsulating a light gas and acetone vapor mixture. The bubble is released from the shock tube's end wall and rises under gravity. In this approach, the interface has a fully 3-D shape. In either case, the interface is accelerated with a M=3 shock wave causing the Richtmyer-Meshkov instability (RMI) to onset. Three planar laser induced fluorescence images are collected during each experiment, one immediately prior to the impulsive acceleration and two at varying stages of the evolution of the RMI. Growth rate data are presented, discussed and compared against numerical simulations of the experiments performed using the LLNL code Raptor.

  11. Richtmyer-Meshkov instability at a gas interface accelerated by a Mach 3 shock wave

    NASA Astrophysics Data System (ADS)

    Anderson, Mark; Oakley, Jason; Motl, Brad; Ranjan, Devesh; Bonazza, Riccardo; Greenough, Jeff

    2003-10-01

    An interface between gases with different acoustic impedance is prepared inside a vertical shock tube with square internal cross section using either of two approaches. In one case, a sinusoidally-shaped thin copper plate, initially separating a heavy from a light gas (with the light gas below the plate) is retracted from the shock tube; the Rayleigh-Taylor (RT) instability drives the subsequent fluid motion, causing the amplitude of the sinusoidal perturbation at the gas interface to grow. In this case, the interface exhibits a dominant 2-D perturbation, with 3-D side effects due to the vortex shedding in the plate's wake and their own RT growth. In the other approach, a discontinous interface is created with a soap film incapsulating a light gas and acetone vapor mixture. The bubble is released from the shock tube's end wall and rises under gravity. In this approach, the interface has a fully 3-D shape. In either case, the interface is accelerated with a M=3 shock wave causing the Richtmyer-Meshkov instability (RMI) to onset. Three planar laser induced fluorescence images are collected during each experiment, one immediately prior to the impulsive acceleration and two at varying stages of the evolution of the RMI. Growth rate data are presented, discussed and compared against numerical simulations of the experiments performed using the LLNL code Raptor.

  12. Modeling Gas-Dynamic Effects in Shock-Tubes for Reaction-Kinetic Measurements

    NASA Astrophysics Data System (ADS)

    Grogan, Kevin; Wang, Qing; Ihme, Matthias

    2014-11-01

    Accurate chemical kinetic models are pivotal for characterizing the effects of new fuel compositions on existing propulsion systems and for developing future combustion technologies. Shock-tube facilities remain invaluable for providing detailed information about ignition delay times, extinction limits, and species time histories for the development and validation of reaction mechanisms. However, viscous and heat transfer effects along the shock-tube wall introduce variations of the thermodynamic state behind the reflected shock wave, thereby affecting the reaction kinetics being measured. These effects have been countered experimentally by the use of driver inserts, extended shock-tube diameters, and the dilution of the test gas. To assist with the design of driver inserts and the selection of operating conditions, a low-order one-dimensional model is developed and compared to two-dimensional Unsteady-Favre-Averaged-Navier-Stokes (UFANS) models as well as experimental data. This model is shown to give accurate predictions of the gas-dynamics in shock-tubes at a computationally efficient cost.

  13. Self-similar dynamic converging shocks - I. An isothermal gas sphere with self-gravity

    NASA Astrophysics Data System (ADS)

    Lou, Yu-Qing; Shi, Chun-Hui

    2014-07-01

    We explore novel self-similar dynamic evolution of converging spherical shocks in a self-gravitating isothermal gas under conceivable astrophysical situations. The construction of such converging shocks involves a time-reversal operation on feasible flow profiles in self-similar expansion with a proper care for the increasing direction of the specific entropy. Pioneered by Guderley since 1942 but without self-gravity so far, self-similar converging shocks are important for implosion processes in aerodynamics, combustion, and inertial fusion. Self-gravity necessarily plays a key role for grossly spherical structures in very broad contexts of astrophysics and cosmology, such as planets, stars, molecular clouds (cores), compact objects, planetary nebulae, supernovae, gamma-ray bursts, supernova remnants, globular clusters, galactic bulges, elliptical galaxies, clusters of galaxies as well as relatively hollow cavity or bubble structures on diverse spatial and temporal scales. Large-scale dynamic flows associated with such quasi-spherical systems (including collapses, accretions, fall-backs, winds and outflows, explosions, etc.) in their initiation, formation, and evolution are likely encounter converging spherical shocks at times. Our formalism lays an important theoretical basis for pertinent astrophysical and cosmological applications of various converging shock solutions and for developing and calibrating numerical codes. As examples, we describe converging shock triggered star formation, supernova explosions, and void collapses.

  14. Plasma properties of driver gas following interplanetary shocks observed by ISEE-3

    NASA Technical Reports Server (NTRS)

    Zwickl, R. D.; Ashbridge, J. R.; Bame, S. J.; Feldman, W. C.; Gosling, J. T.; Smith, E. J.

    1982-01-01

    Plasma fluid parameters calculated from solar wind and magnetic field data obtained on ISEE 3 were studied. The characteristic properties of driver gas following interplanetary shocks was determined. Of 54 shocks observed from August 1978 to February 1980, nine contained a well defined driver gas that was clearly identifiable by a discontinuous decrease in the average proton temperature across a tangential discontinuity. While helium enhancements were present in all of nine of these events, only about half of them contained simultaneous changes in the two quantities. Often the He/H ratio changed over a period of minutes. Simultaneous with the drop in proton temperature the helium and electron temperature decreased abruptly. In some cases the proton temperature depression was accompanied by a moderate increase in magnetic field magnitude with an unusually low variance and by an increase in the ratio of parallel to perpendicular temperature. The drive gas usually displayed a bidirectional flow of suprathermal solar wind electrons at higher energies.

  15. Effect of screening layers of a suspension in a gas on shock-wave reflection

    NASA Astrophysics Data System (ADS)

    Ivandaev, A. I.; Kutushev, A. G.

    1985-02-01

    The effect of a screening layer of a suspension of finely dispersed particles in a gas on the reflection of a plane nonstationary shock wave from a rigid wall is analyzed numerically. The possibility of using limiting (equilibrium and frozen) flow schemes in the layer to calcuate the reflection process is assessed. The effect of screening-layer parameters on the maximum pressure on the wall is investigated. It is noted that the results may be of use in the design of systems of dust protection against shock waves and in the analysis of gasdynamic techniques for the deposition of powder coatings.

  16. CAS22 - FORTRAN program for fast design and analysis of shock-free airfoil cascades using fictitious-gas concept

    NASA Technical Reports Server (NTRS)

    Dulikravich, D. S.; Sobieczky, H.

    1982-01-01

    A user-oriented computer program, CAS22, was developed that is applicable to aerodynamic analysis and transonic shock-free redesign of existing two-dimensional cascades of airfoils. This FORTRAN program can be used: (1) as an analysis code for full-potential, transonic, shocked or shock-free cascade flows; (2) as a design code for shock-free cascades that uses Sobieczky's fictitious-gas concept; and (3) as a shock-free design code followed automatically by the analysis in order to confirm that the newly obtained cascade shape provides for an entirely shock-free transonic flow field. A four-level boundary-conforming grid of an O type is generated. The shock-free design is performed by implementing Sobieczky's fictitious-gas concept of elliptic continuation from subsonic into supersonic flow domains. Recomputation inside each supersonic zone is performed by the method of characteristics in the rheograph plane by using isentropic gas relations. Besides converting existing cascade shapes with multiple shocked supersonic regions into shock-free cascades, CAS22 can also unchoke previously choked cascades and make them shock free.

  17. Heat-flow equation motivated by the ideal-gas shock wave.

    PubMed

    Holian, Brad Lee; Mareschal, Michel

    2010-08-01

    We present an equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, in order to model shockwave propagation in gases. Our approach is motivated by the observation of a disequilibrium among the three components of temperature, namely, the difference between the temperature component in the direction of a planar shock wave, versus those in the transverse directions. This difference is most prominent near the shock front. We test our heat-flow equation for the case of strong shock waves in the ideal gas, which has been studied in the past and compared to Navier-Stokes solutions. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations of hard spheres under strong shockwave conditions.

  18. Effect of the dynamic pressure on the shock wave structure in a rarefied polyatomic gas

    SciTech Connect

    Taniguchi, Shigeru Sugiyama, Masaru; Arima, Takashi; Ruggeri, Tommaso

    2014-01-15

    We study the shock wave structure in a rarefied polyatomic gas based on a simplified model of extended thermodynamics in which the dissipation is due only to the dynamic pressure. In this case the differential system is very simple because it is a variant of Euler system with a new scalar equation for the dynamic pressure [T. Arima, S. Taniguchi, T. Ruggeri, and M. Sugiyama, Phys. Lett. A 376, 2799–2803 (2012)]. It is shown that this theory is able to describe the three types of the shock wave structure observed in experiments: the nearly symmetric shock wave structure (Type A, small Mach number), the asymmetric structure (Type B, moderate Mach number), and the structure composed of thin and thick layers (Type C, large Mach number)

  19. Heat-flow equation motivated by the ideal-gas shock wave.

    PubMed

    Holian, Brad Lee; Mareschal, Michel

    2010-08-01

    We present an equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, in order to model shockwave propagation in gases. Our approach is motivated by the observation of a disequilibrium among the three components of temperature, namely, the difference between the temperature component in the direction of a planar shock wave, versus those in the transverse directions. This difference is most prominent near the shock front. We test our heat-flow equation for the case of strong shock waves in the ideal gas, which has been studied in the past and compared to Navier-Stokes solutions. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations of hard spheres under strong shockwave conditions. PMID:20866940

  20. Cooking a `Sausage': the impact of merger shocks in cluster gas and galaxy evolution

    NASA Astrophysics Data System (ADS)

    Stroe, Andra; Sobral, David; Harwood, Jeremy; Van Weeren, Reinout J.; Rumsey, Clare; Intema, Huib; Röttgering, Huub; Brüggen, Marcus; Saunders, Richard; Hardcastle, Martin; Hoeft, Matthias

    2015-01-01

    Galaxy clusters mainly grow through mergers with other clusters and groups. Major mergers give rise to important astrophysical phenomena such as the segregation of dark and luminous matter and the formation of cluster-wide traveling shocks and also drive galaxy evolution. The observable effects of shock waves can be seen at radio wavelengths as relics: elongated, diffuse synchrotron emitting areas located at the periphery of merging clusters. Despite the great interest in relics, candidates with simple geometry, undisturbed morphology and high surface brightness are scarce. The `Sausage' cluster hosts an extraordinary Mpc-wide relic, which enables us to study to study particle acceleration and the effects of shocks on cluster galaxies. We use a unique combination of facilities (INT, WHT, Keck, Subaru, CFHT, GMRT, WSRT, AMI) to obtain the first cluster-wide, multi-wavelength, multi-method analysis aimed at giving a complete picture of a merging cluster with relics. Using the radio data, we derive shock properties and the magnetic field structure for the relic. Using spectral modeling, we test acceleration and electron energy-loss mechanisms and resolve the discrepancy between the Mach number calculated from the radio and X-rays. Our results indicate that particles are shock-accelerated, but turbulent re-acceleration or unusually efficient transport of particles in the downstream area and line-of-sight mixing are important effects. We demonstrate the feasibility of high-frequency observations of radio relics, by presenting a 16 GHz detection of the `Sausage' relic. The radio analysis is complemented by Hα mapping of the cluster volume, aimed at providing the first direct test as to whether the shock drives or prohibits star formation. We find numerous Hα emitting galaxies in close proximity to the radio relic which are extremely massive, metal-rich, mostly star-forming with evidence for gas mass loss though outflows. We speculate that the complex interaction

  1. Conical flow near singular rays. [shock generation in ideal gas

    NASA Technical Reports Server (NTRS)

    Zahalak, G. I.; Myers, M. K.

    1974-01-01

    The steady flow of an ideal gas past a conical body is investigated by the method of matched asymptotic expansions, with particular emphasis on the flow near the singular ray occurring in linearized theory. The first-order problem governing the flow in this region is formulated, leading to the equation of Kuo, and an approximate solution is obtained in the case of compressive flow behind the main front. This solution is compared with the results of previous investigations with a view to assessing the applicability of the Lighthill-Whitham theories.

  2. Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas

    NASA Technical Reports Server (NTRS)

    Baty, Roy S.; Farassat, Fereidoun; Hargreaves, John

    2007-01-01

    Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. To use conservations laws, smooth pre-distributions of the Dirac delta measure are applied whose supports are contained within the shock thickness. Furthermore, smooth pre-distributions of the Heaviside function are applied which vary from zero to one across the shock wave. It is shown that if the equations of motion are expressed in nonconservative form then the relationships between the jump functions for the flow parameters may be found unambiguously. The analysis yields the classical Rankine-Hugoniot jump conditions for an inviscid shock wave. Moreover, non-monotonic entropy jump conditions are obtained for both inviscid and viscous flows. The report shows that products of generalized functions may be defined consistently using nonstandard analysis; however, physically meaningful products of generalized functions must be determined from the physics of the problem and not the mathematical form of the governing equations.

  3. Shock Initiation Behavior of PBXN-9 Determined by Gas Gun Experiments

    NASA Astrophysics Data System (ADS)

    Sanchez, N. J.; Gustavsen, R. L.; Hooks, D. E.

    2009-12-01

    The shock to detonation transition was evaluated in the HMX based explosive PBXN-9 by a series of light-gas gun experiments. PBXN-9 consists of 92 wt% HMX, 2wt% Hycar 4054 & 6 wt&percent; dioctyl adipate with a density of 1.75 g/cm3 and 0.8&% voids. The experiments were designed to understand the specifics of wave evolution and the run distance to detonation as a function of input shock pressure. These experiments were conducted on gas guns in order to vary the input shock pressure accurately. The primary diagnostics were embedded magnetic gauges, which are based on Faraday's law of induction, and Photon Doppler Velocimetry (PDV). The run distance to detonation vs. shock pressure, or "Pop plot," was redefined as log(X) = 2.14-1.82 log (P), which is substantially different than previous data. The Hugoniot was refined as Us = 2.32+2.211 Up. This data will be useful for the development of predictive models for the safety and performance of PBXN-9 along with providing increased understanding of HMX based explosives in varying formulations.

  4. Shock initiation behavior of PBXN-9 determined by gas gun experiments

    NASA Astrophysics Data System (ADS)

    Sanchez, Nathaniel; Gustavsen, Richard; Hooks, Daniel

    2009-06-01

    The shock to detonation transition was evaluated in the HMX based explosive PBXN-9 by a series of light-gas gun experiments. PBXN-9 consists of 92 wt% HMX, 2wt% Hycar 4054 & 6 wt% dioctyl adipate with a density of 1.75 g/cm^3 and 0.8% voids. The experiments were designed to understand the specifics of wave evolution and the run distance to detonation as a function of input shock pressure. These experiments were conducted on gas guns in order to vary the input shock pressure accurately. The primary diagnostics are embedded magnetic gauges which are based on Faraday's law of induction along with photon Doppler velocimetry (PDV). The run distance to detonation vs. shock pressure, or ``Pop plot,'' was redefined as log (X*) = 2.14 -- 1.82 log (P), which is substantially different than previous data. The Hugoniot was refined as Us = 2.32 + 2.21 Up. This data will be useful for the development of predictive models for the safety and performance of PBXN-9 in addition to providing an increased understanding of HMX based explosives in varying formulations.

  5. Shock initiation behavior of PBXN-9 determined by gas gun experiments

    SciTech Connect

    Sanchez, Nathaniel J; Gustavsen, Richard L; Hooks, Daniel E

    2009-01-01

    The shock to detonation transition was evaluated in the HMX based explosive PBXN-9 by a series of light-gas gun experiments. PBXN-9 consists of 92 wt% HMX, 2wt% Hycar 4054 & 6 wt% dioctyl adipate with a density of 1.75 g/cm{sup 3} and 0.8% voids. The experiments were designed to understand the specifics of wave evolution and the run distance to detonation as a function of input shock pressure. These experiments were conducted on gas guns in order to vary the input shock pressure accurately. The primary diagnostics were embedded magnetic gauges, which are based on Faraday's law of induction, and Photon Doppler Velocimetry (PDV). The run distance to detonation vs. shock pressure, or 'Pop plot,' was redefined as log(X*) = 2.14-1.82 log(P), which is substantially different than previous data. The Hugoniot was refined as U{sub s} = 2.32 + 2.21 U{sub p}. This data will be useful for the development of predictive models for the safety and performance of PBXN-9 along with providing increased understanding of HMX based explosives in varying formulations.

  6. Detection of shocked atomic gas in the Kleinmann-Low nebula

    NASA Technical Reports Server (NTRS)

    Werner, M.; Crawford, M. K.; Genzel, R.; Hollenbach, D. J.; Townes, C. H.; Watson, F. M.

    1984-01-01

    The 63 micrometer (3)p(1)-(3)P(2) fine structure line emission of neutral atomic oxygen at the center of the Orion nebula with a resolution of 30" is presented. There are three main emission peaks. One is associated with the region of strongest thermal radio continuum radiation close to the Trapezium cluster, and probably arises at the interface between the HII region and the dense Orion molecular cloud. The other two line emission peaks, associated with the Kleinmann Low nebula, are similar in both distribution and velocity to those of the 2 micrometer S(1) line of molecular hydrogen and of the high velocity wings of rotational CO emission. The OI emission from the KL nebula can be produced in the shocked gas associated with the mass outflows in this region and is an important coolant of the shocked gas.

  7. Detection of shocked atomic gas in the Kleinmann-Low nebula

    NASA Technical Reports Server (NTRS)

    Werner, M. W.; Hollenbach, D. J.; Crawford, M. K.; Genzel, R.; Townes, C. H.; Watson, D. M.

    1984-01-01

    The 63 micrometer (3)P(1)-(3)P(2) fine structure line emission of neutral atomic oxygen at the center of the Orion nebula with a resolution of 30'' is presented. There are three main emission peaks. One is associated with the region of strongest thermal radio continuum radiation close to the Trapezium cluster, and probably arises at the interface between the H II region and the dense Orion molecular cloud. The other two line emission peaks, associated with the Kleinmann-Low nebula, are similar in both distribution and velocity to those of the 2 micrometer S(1) line of molecular hydrogen and of the high velocity wings of rotational CO emission. The OI emission from the KL nebula can be produced in the shocked gas associated with the mass outflows in this region and is an important coolant of the shocked gas.

  8. Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  9. Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  10. Star Formation Suppression Due to Jet Feedback in Radio Galaxies with Shocked Warm Molecular Gas

    NASA Astrophysics Data System (ADS)

    Lanz, Lauranne; Ogle, Patrick M.; Alatalo, Katherine; Appleton, Philip N.

    2016-07-01

    We present Herschel observations of 22 radio galaxies, selected for the presence of shocked, warm molecular hydrogen emission. We measured and modeled spectral energy distributions in 33 bands from the ultraviolet to the far-infrared to investigate the impact of jet feedback on star formation activity. These galaxies are massive, early-type galaxies with normal gas-to-dust ratios, covering a range of optical and infrared colors. We find that the star formation rate (SFR) is suppressed by a factor of ˜3–6, depending on how molecular gas mass is estimated. We suggest that this suppression is due to the shocks driven by the radio jets injecting turbulence into the interstellar medium (ISM), which also powers the luminous warm H2 line emission. Approximately 25% of the sample shows suppression by more than a factor of 10. However, the degree of SFR suppression does not correlate with indicators of jet feedback including jet power, diffuse X-ray emission, or intensity of warm molecular H2 emission, suggesting that while injected turbulence likely impacts star formation, the process is not purely parameterized by the amount of mechanical energy dissipated into the ISM. Radio galaxies with shocked warm molecular gas cover a wide range in SFR–stellar mass space, indicating that these galaxies are in a variety of evolutionary states, from actively star-forming and gas-rich to quiescent and gas-poor. SFR suppression appears to have the largest impact on the evolution of galaxies that are moderately gas-rich.

  11. Gas dynamics in barred spirals - Gaseous density waves and galactic shocks

    NASA Technical Reports Server (NTRS)

    Roberts, W. W., Jr.; Van Albada, G. D.; Huntley, J. M.

    1979-01-01

    Steady-state gasdynamical studies, previously limited to tightly wound normal spiral galaxies, are extended to models of barred spirals with a 5% to 10% perturbing potential. The models show that a strong wave manifestation is an important constituent of the bar structure in many barred spirals and that a density-wave shock wave can form a bar structure as pronounced as the narrow bars often evident in optical photographs of barred spirals. The dark narrow dust lanes often observed along the leading edges of bar structures are identified as tracers of shocks, and it is found that strong shocks along a bar structure during even a small part of a galaxy's lifetime might easily deplete a large enough proportion of the gas to cause a lack of gas in the inner annuli encompassing the bar by the time of the present epoch. It is emphasized that even moderate-amplitude barlike perturbations in the disk can drive large noncircular gas motions, typically 50 to 150 km/s.

  12. Molecular hydrogen line ratios in four regions of shock-excited gas

    NASA Technical Reports Server (NTRS)

    Burton, M. G.; Brand, P. W. J. L.; Geballe, T. R.; Webster, A. S.

    1989-01-01

    Five emission lines of molecular hydrogen, with wavelengths in the ranges of 2.10-2.25 and 3.80-3.85 microns, have been observed in four objects of different type in which the line emission is believed to be excited by shocks. The relative intensities of the lines 1 - 0 S(1):1 - 0 S(O):2 - 1 S(1) are approximately 10.5:2.5:1.0 in all four objects. The 0 - 0 S(13):1 - 0 O(7) line ratio, however, varies from 1.05 in OMC-1 to about 2.3 in the Herbig-Haro object HH 7. The excitation temperature derived from the S(13) and O(7) lines is higher than that derived from the 1 - 0 and 2 - 1 S(1) lines in all four objects, so the shocked gas in these objects cannot be characterized by a single temperature. The constancy of the (1-0)/(2-1) S(1) line ratio between sources suggests that the post-shock gas is 'thermalized' in each source. The S(13)/O(7) ratio is particularly sensitive to the density and temperature conditions in the gas.

  13. Highly Excited H2 in Herbig-Haro 7: Formation Pumping in Shocked Molecular Gas?

    NASA Astrophysics Data System (ADS)

    Pike, R. E.; Geballe, T. R.; Burton, M. G.; Chrysostomou, A.

    2016-05-01

    We have obtained K-band spectra at R ˜ 5000 and an angular resolution of 0.″3 of a section of the Herbig-Haro 7 (HH7) bow shock, using the Near-Infrared Integral Field Spectrograph at Gemini North. Present in the portion of the data cube corresponding to the brightest part of the bow shock are emission lines of H2 with upper state energies ranging from ˜6000 K to the dissociation energy of H2, ˜50,000 K. Because of low signal-to-noise ratios, the highest excitation lines cannot be easily seen elsewhere in the observed region. However, excitation temperatures, measured throughout much of the observed region using lines from levels as high as 25,000 K, are a strong function of upper level energy, indicating that the very highest levels are populated throughout. The level populations in the brightest region are well fit by a two-temperature model, with 98.5% of the emitting gas at T = 1800 K and 1.5% at T = 5200 K. The bulk of the H2 line emission in HH7, from the 1800 K gas, has previously been well-modeled by a continuous shock, but the 5200 K cozmponent is inconsistent with standalone standard continuous shock models. We discuss various possible origins for the hot component and suggest that this component is H2 newly reformed on dust grains and then ejected from them, presumably following dissociation of some of the H2 by the shock.

  14. Numerical Investigation into the Performance of a Rarefaction Shock Wave Cutter for Offshore Oil-Gas Platform Removal

    SciTech Connect

    Morris, J P; Glenn, L A; Antoun, T H; Lomov, I N

    2001-06-14

    The phase change in iron at 13 GPa results in the formation of rarefaction shock waves upon release. The interaction of multiple rarefaction shock waves induces high tensile stresses within a narrow zone, causing smooth spall. This effect can be exploited to sever cylindrical cross-section pipes, such as those supporting decommissioned offshore oil and gas platforms, using a minimal amount of explosive. Consequently, costs can be reduced and environmental impact minimized. They discuss the numerical techniques used to simulate rarefaction shock waves and the damage to steel resulting from the interaction of multiple rarefaction shock waves.

  15. Shock-induced collapse of a gas bubble in shockwave lithotripsy.

    PubMed

    Johnsen, Eric; Colonius, Tim

    2008-10-01

    The shock-induced collapse of a pre-existing nucleus near a solid surface in the focal region of a lithotripter is investigated. The entire flow field of the collapse of a single gas bubble subjected to a lithotripter pulse is simulated using a high-order accurate shock- and interface-capturing scheme, and the wall pressure is considered as an indication of potential damage. Results from the computations show the same qualitative behavior as that observed in experiments: a re-entrant jet forms in the direction of propagation of the pulse and penetrates the bubble during collapse, ultimately hitting the distal side and generating a water-hammer shock. As a result of the propagation of this wave, wall pressures on the order of 1 GPa may be achieved for bubbles collapsing close to the wall. The wall pressure decreases with initial stand-off distance and pulse width and increases with pulse amplitude. For the stand-off distances considered in the present work, the wall pressure due to bubble collapse is larger than that due to the incoming shockwave; the region over which this holds may extend to ten initial radii. The present results indicate that shock-induced collapse is a mechanism with high potential for damage in shockwave lithotripsy.

  16. Shock-induced collapse of a gas bubble in shockwave lithotripsy

    PubMed Central

    Johnsen, Eric; Colonius, Tim

    2008-01-01

    The shock-induced collapse of a pre-existing nucleus near a solid surface in the focal region of a lithotripter is investigated. The entire flow field of the collapse of a single gas bubble subjected to a lithotripter pulse is simulated using a high-order accurate shock- and interface-capturing scheme, and the wall pressure is considered as an indication of potential damage. Results from the computations show the same qualitative behavior as that observed in experiments: a re-entrant jet forms in the direction of propagation of the pulse and penetrates the bubble during collapse, ultimately hitting the distal side and generating a water-hammer shock. As a result of the propagation of this wave, wall pressures on the order of 1 GPa may be achieved for bubbles collapsing close to the wall. The wall pressure decreases with initial stand-off distance and pulse width and increases with pulse amplitude. For the stand-off distances considered in the present work, the wall pressure due to bubble collapse is larger than that due to the incoming shockwave; the region over which this holds may extend to ten initial radii. The present results indicate that shock-induced collapse is a mechanism with high potential for damage in shockwave lithotripsy. PMID:19062841

  17. Spectral Modification of Shock Accelerated Ions Using a Hydrodynamically Shaped Gas Target

    NASA Astrophysics Data System (ADS)

    Tresca, O.; Dover, N. P.; Cook, N.; Maharjan, C.; Polyanskiy, M. N.; Najmudin, Z.; Shkolnikov, P.; Pogorelsky, I.

    2015-08-01

    We report on reproducible shock acceleration from irradiation of a λ =10 μ m CO2 laser on optically shaped H2 and He gas targets. A low energy laser prepulse (I ≲1014 W cm-2 ) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I >1016 W cm-2 ) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40 μ m ), broadband beams of He+ and H+ are routinely produced, while for shorter gradients (≲20 μ m ), quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations.

  18. Spectral modification of shock accelerated ions using a hydrodynamically shaped gas target

    SciTech Connect

    Tresca, O.; Polyanskiy, M. N.; Dover, N. P.; Cook, N.; Maharjan, C.; Najmudin, Z.; Shkolnikov, P.; Pogorelsky, I.

    2015-08-28

    We report on reproducible shock acceleration from irradiation of a λ=10 μm CO2 laser on optically shaped H2 and He gas targets. A low energy laser prepulse (I≲1014 W cm–2) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I>1016 W cm–2) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40 μm), broadband beams of He+ and H+ were routinely produced, whilst for shorter gradients (≲20 μm), quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations.

  19. Spectral modification of shock accelerated ions using a hydrodynamically shaped gas target

    DOE PAGES

    Tresca, O.; Polyanskiy, M. N.; Dover, N. P.; Cook, N.; Maharjan, C.; Najmudin, Z.; Shkolnikov, P.; Pogorelsky, I.

    2015-08-28

    We report on reproducible shock acceleration from irradiation of a λ=10 μm CO2 laser on optically shaped H2 and He gas targets. A low energy laser prepulse (I≲1014 W cm–2) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I>1016 W cm–2) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40 μm), broadband beams of He+ and H+ were routinely produced, whilst for shorter gradients (≲20 μm),more » quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations.« less

  20. Spectral Modification of Shock Accelerated Ions Using a Hydrodynamically Shaped Gas Target.

    PubMed

    Tresca, O; Dover, N P; Cook, N; Maharjan, C; Polyanskiy, M N; Najmudin, Z; Shkolnikov, P; Pogorelsky, I

    2015-08-28

    We report on reproducible shock acceleration from irradiation of a λ=10  μm CO_{2} laser on optically shaped H_{2} and He gas targets. A low energy laser prepulse (I≲10^{14}  W cm^{-2}) is used to drive a blast wave inside the gas target, creating a steepened, variable density gradient. This is followed, after 25 ns, by a high intensity laser pulse (I>10^{16}  W cm^{-2}) that produces an electrostatic collisionless shock. Upstream ions are accelerated for a narrow range of prepulse energies. For long density gradients (≳40  μm), broadband beams of He^{+} and H^{+} are routinely produced, while for shorter gradients (≲20  μm), quasimonoenergetic acceleration of protons is observed. These measurements indicate that the properties of the accelerating shock and the resultant ion energy distribution, in particular the production of narrow energy spread beams, is highly dependent on the plasma density profile. These findings are corroborated by 2D particle-in-cell simulations. PMID:26371658

  1. Improvement of pump tubes for gas guns and shock tube drivers

    NASA Technical Reports Server (NTRS)

    Bogdanoff, D. W.

    1990-01-01

    In a pump tube, a gas is mechanically compressed, producing very high pressures and sound speeds. The intensely heated gas produced in such a tube can be used to drive light gas guns and shock tubes. Three concepts are presented that have the potential to allow substantial reductions in the size and mass of the pump tube to be achieved. The first concept involves the use of one or more diaphragms in the pump tube, thus replacing a single compression process by multiple, successive compressions. The second concept involves a radical reduction in the length-to-diameter ratio of the pump tube and the pump tube piston. The third concept involves shock heating of the working gas by high explosives in a cyclindrical geometry reusable device. Preliminary design analyses are performed on all three concepts and they appear to be quite feasible. Reductions in the length and mass of the pump tube by factors up to about 11 and about 7, respectively, are predicted, relative to a benchmark conventional pump tube.

  2. Numerical studies of real-gas effects on two-dimensional hypersonic shock-wave/boundary-layer interaction

    NASA Astrophysics Data System (ADS)

    Furumoto, Gregory H.; Zhong, Xiaolin; Skiba, John C.

    1997-01-01

    Nonequilibrium real-gas effects on surface heating rates, skin friction, and flow field unsteadiness of two-dimensional hypersonic shock-wave/boundary-layer interaction were studied by numerical simulations. The unsteady Navier-Stokes equations with nonequilibrium vibrational and chemical models for five-species air were solved by a finite-volume second-order TVD scheme together with a third-order semi-implicit Runge-Kutta scheme. Two cases of high-enthalpy shock/boundary layer interaction problems were studied in this paper. The freestream enthalpy was high enough to produce vibrational excitation and dissociation/recombination chemistry behind the shock. The first case was a steady two-dimensional shock/boundary layer interaction on a flat plate with a mixture of N2 and O2 in the freestream. It was found that the real gas effects reduce the size of the shock induced separation bubble and the magnitude of the surface heating rates. The second case was a self-sustained unsteady type IV shock-shock interference heating of a pure N2 flow over a cylinder. The results showed that type IV shock-shock interference heating flows with real-gas effects are inherently unsteady. Vortices are generated and shed off near the jet impingement point. This periodic shedding of the vortices contributes to the self-sustained oscillations of both the jet and other parts of the flow fields. In addition, the real-gas effects reduce the level of peak surface heating and peak surface pressure due to endothermic real-gas effects.

  3. Computational study of the shock driven instability of a multiphase particle-gas system

    DOE PAGES

    None, None

    2016-02-01

    This paper considers the interaction of a shock wave with a multiphase particle-gas system which creates an instability somewhat similar to the Richtmyer-Meshkov instability but with a larger parameter space. Because this parameter space is large, we only present an introductory survey of the effects of many of these parameters. We highlight the effects of particle-gas coupling, incident shock strength, particle size, effective system density differences, and multiple particle relaxation time effects. We focus on dilute flows with mass loading up to 40% and do not attempt to cover all parametric combinations. Instead, we vary one parameter at a timemore » leaving additional parametric combinations for future work. The simulations are run with the Ares code, developed at Lawrence Livermore National Laboratory, which uses a multiphase particulate transport method to model two-way momentum and energy coupling. A brief validation of these models is presented and coupling effects are explored. It is shown that even for small particles, on the order of 1μm, multi-phase coupling effects are important and diminish the circulation deposition on the interface by up to 25%. These coupling effects are shown to create large temperature deviations from the dusty gas approximation, up to 20% greater, especially at higher shock strengths. It is also found that for a multiphase instability, the vortex sheet deposited at the interface separates into two sheets. In conclusion, depending on the particle and particle-gas Atwood numbers, the instability may be suppressed or enhanced by the interactions of these two vortex sheets.« less

  4. Computational study of the shock driven instability of a multiphase particle-gas system

    NASA Astrophysics Data System (ADS)

    McFarland, Jacob A.; Black, Wolfgang J.; Dahal, Jeevan; Morgan, Brandon E.

    2016-02-01

    This paper considers the interaction of a shock wave with a multiphase particle-gas system which creates an instability similar in some ways to the Richtmyer-Meshkov instability but with a larger parameter space. As this parameter space is large, we only present an introductory survey of the effects of many of these parameters. We highlight the effects of particle-gas coupling, incident shock strength, particle size, effective system density differences, and multiple particle relaxation time effects. We focus on dilute flows with mass loading up to 40% and do not attempt to cover all parametric combinations. Instead, we vary one parameter at a time leaving additional parametric combinations for future work. The simulations are run with the Ares code, developed at Lawrence Livermore National Laboratory, which uses a multiphase particulate transport method to model two-way momentum and energy coupling. A brief validation of these models is presented and coupling effects are explored. It is shown that even for small particles, on the order of 1 μm, multi-phase coupling effects are important and diminish the circulation deposition on the interface by up to 25%. These coupling effects are shown to create large temperature deviations from the dusty gas approximation, up to 20% greater, especially at higher shock strengths. It is also found that for a multiphase instability, the vortex sheet deposited at the interface separates into two sheets. Depending on the particle and particle-gas Atwood numbers, the instability may be suppressed or enhanced by the interactions of these two vortex sheets.

  5. Propagation of a strong spherical shock wave in a gravitating or non-gravitating dusty gas with exponentially varying density

    NASA Astrophysics Data System (ADS)

    Nath, G.; Vishwakarma, J. P.

    2016-06-01

    The propagation of a strong spherical shock wave in a dusty gas with or without self-gravitational effects is investigated in the case of isothermal and adiabatic flows. The dusty gas is assumed to be a mixture of small solid particles and perfect gas. The equilibrium flow conditions are assumed to be maintained, and the density of the mixture is assumed to be varying and obeying an exponential law. Non-similarity solutions are obtained and the effects of variations of the mass concentration of solid particles in the mixture and the ratio of the density of solid particles to the initial density of the gas, and the presence of self-gravitational field on the flow variables are investigated at given times. Our analysis reveals that after inclusion of gravitational field effects surprisingly the shock strength increases and remarkable differences are found in the distribution of flow variables. An increase in time also, increases the shock strength. Further, it is investigated that the consideration of isothermal flow increases the shock strength, and removes the singularity in the density distribution. Also, the presence of gravitational field increases the compressibility of the medium, due to which it is compressed and therefore the distance between the inner contact surface and the shock surface is reduced. The shock waves in self-gravitating dusty gas can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, star formation and shocks in stellar explosion, nuclear explosion, in industry, rupture of a pressurized vessel and explosion in the ionosphere. Other potential applications of this study include analysis of data from exploding wire experiments and cylindrically symmetric hypersonic flow problems associated with meteors or re-entry of vehicles etc. A comparison is made between the solutions in the cases of the gravitating and the non-gravitating media. The obtained solutions are applicable for

  6. KINEMATICS OF SHOCKED MOLECULAR GAS ADJACENT TO THE SUPERNOVA REMNANT W44

    SciTech Connect

    Sashida, Tomoro; Oka, Tomoharu; Tanaka, Kunihiko; Aono, Kazuya; Matsumura, Shinji; Nagai, Makoto; Seta, Masumichi

    2013-09-01

    We mapped molecular gas toward the supernova remnant W44 in the HCO{sup +} J = 1-0 line with the Nobeyama Radio Observatory 45 m telescope and in the CO J = 3-2 line with the Atacama Submillimeter Telescope Experiment 10 m telescope. High-velocity emission wings were detected in both lines over the area where the radio shell of W44 overlaps with the molecular cloud in the plane of the sky. We found that the average velocity distributions of the wing emission can be fit by a uniform expansion model. The best-fit expansion velocities are 12.2 {+-} 0.3 km s{sup -1} and 13.2 {+-} 0.2 km s{sup -1} in HCO{sup +} and CO, respectively. The non-wing CO J = 3-2 component is also fit by the same model with an expansion velocity of 4.7 {+-} 0.1 km s{sup -1}. This component might be dominated by a post-shock higher-density region where the shock velocity had slowed down. The kinetic energy of the shocked molecular gas is estimated to be (3.5 {+-} 1.3) Multiplication-Sign 10{sup 49} erg. Adding this and the energy of the previously identified H I shell, we conclude that (1.2 {+-} 0.2) Multiplication-Sign 10{sup 50} erg has been converted into gas kinetic energy from the initial baryonic energy of the W44 supernova. We also found ultra-high-velocity CO J = 3-2 wing emission with a velocity width of {approx}100 km s{sup -1} at (l, b) = (+34. Degree-Sign 73, -0. Degree-Sign 47). The origin of this extremely high velocity wing is a mystery.

  7. Strong cylindrical shock wave in a self-gravitating rotational axisymmetric dusty gas with density varying exponentially

    NASA Astrophysics Data System (ADS)

    Nath, Gorakh

    2016-07-01

    The propagation of a strong cylindrical shock wave in a self-gravitating and rotational axisymmetric dusty gas, having variable azimuthal and axial fluid velocities is investigated. The dusty gas is assumed to be a mixture of small solid particles and perfect gas. The equilibrium flow conditions are assumed to be maintained. The density of the mixture and the fluid velocities in the ambient medium are assumed to be varying and obeying an exponential law. The shock wave moves with variable velocity and the total energy of the wave is non-constant. Non-similarity solutions are obtained and the effects of variation of the mass concentration of solid particles in the mixture, the ratio of the density of solid particles to the initial density of the gas, and the gravitational parameter on the flow variables in the region behind the shock are investigated at a given time. Also, a comparison between the isothermal and adiabatic flow is made.

  8. Observation of ShockWaves in a Strongly Interacting Fermi Gas

    SciTech Connect

    Kulkarni, M.; Joseph, J.A.; Thomas, J.E.; Abanov, A.G.

    2011-04-11

    We study collisions between two strongly interacting atomic Fermi gas clouds. We observe exotic nonlinear hydrodynamic behavior, distinguished by the formation of a very sharp and stable density peak as the clouds collide and subsequent evolution into a boxlike shape. We model the nonlinear dynamics of these collisions by using quasi-1D hydrodynamic equations. Our simulations of the time-dependent density profiles agree very well with the data and provide clear evidence of shock wave formation in this universal quantum hydrodynamic system.

  9. Gas Evolution Dynamics in Godunov-Type Schemes and Analysis of Numerical Shock Instability

    NASA Technical Reports Server (NTRS)

    Xu, Kun

    1999-01-01

    In this paper we are going to study the gas evolution dynamics of the exact and approximate Riemann solvers, e.g., the Flux Vector Splitting (FVS) and the Flux Difference Splitting (FDS) schemes. Since the FVS scheme and the Kinetic Flux Vector Splitting (KFVS) scheme have the same physical mechanism and similar flux function, based on the analysis of the discretized KFVS scheme the weakness and advantage of the FVS scheme are closely observed. The subtle dissipative mechanism of the Godunov method in the 2D case is also analyzed, and the physical reason for shock instability, i.e., carbuncle phenomena and odd-even decoupling, is presented.

  10. A molecular survey of outflow gas: velocity-dependent shock chemistry and the peculiar composition of the EHV gas

    NASA Astrophysics Data System (ADS)

    Tafalla, M.; Santiago-García, J.; Hacar, A.; Bachiller, R.

    2010-11-01

    Context. Bipolar outflows from Class 0 protostars often present two components in their CO spectra that have different kinematic behaviors: a smooth outflow wing and a discrete, extremely high-velocity (EHV) peak. Aims: To better understand the origin of these two outflow components, we have studied and compared their molecular composition. Methods: We carried out a molecular survey of the outflows powered by L1448-mm and IRAS 04166+2706, two sources with prominent wing and EHV components. For each source, we observed a number of molecular lines towards the brightest outflow position and used them to determine column densities for 12 different molecular species. Results: The molecular composition of the two outflows is very similar. It presents systematic changes with velocity that we analyze by dividing the outflow in three chemical regimes, two of them associated with the wing component and the other the EHV gas. The analysis of the two wing regimes shows that species like H2CO and CH3OH favor the low-velocity gas, while SiO and HCN are more abundant in the fastest gas. This fastest wing gas presents strong similarities with the composition of the “chemically active” L1157 outflow (whose abundances we re-evaluate in an appendix). We find that the EHV regime is relatively rich in O-bearing species compared to the wing regime. The EHV gas is not only detected in CO and SiO (already reported elsewhere), but also in SO, CH3OH, and H2CO (newly reported here), with a tentative detection in HCO+. At the same time, the EHV regime is relatively poor in C-bearing molecules like CS and HCN, for which we only obtain weak detections or upper limits despite deep integrations. We suggest that this difference in composition arises from a lower C/O ratio in the EHV gas. Conclusions: The different chemical compositions of the wing and EHV regimes suggest that these two outflow components have different physical origins. The wing component is better explained by shocked ambient

  11. Magnetogasdynamic spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes

    NASA Astrophysics Data System (ADS)

    Nath, G.; Vishwakarma, J. P.

    2016-11-01

    Similarity solutions are obtained for the flow behind a spherical shock wave in a non-ideal gas under gravitational field with conductive and radiative heat fluxes, in the presence of a spatially decreasing azimuthal magnetic field. The shock wave is driven by a piston moving with time according to power law. The radiation is considered to be of the diffusion type for an optically thick grey gas model and the heat conduction is expressed in terms of Fourier's law for heat conduction. Similarity solutions exist only when the surrounding medium is of constant density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. It is shown that an increase of the gravitational parameter or the Alfven-Mach number or the parameter of the non-idealness of the gas decreases the compressibility of the gas in the flow-field behind the shock, and hence there is a decrease in the shock strength. The pressure and density vanish at the inner surface (piston) and hence a vacuum is formed at the center of symmetry. The shock waves in conducting non-ideal gas under gravitational field with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of a flare produced shock in the solar wind, central part of star burst galaxies, nuclear explosion etc. The solutions obtained can be used to interpret measurements carried out by space craft in the solar wind and in neighborhood of the Earth's magnetosphere.

  12. Dynamics of the Shocked Gas in the Eta Carinae System as Seen by Chandra

    NASA Astrophysics Data System (ADS)

    Corcoran, M. F.; Hamaguchi, K.; Henley, D. B.; Ishibashi, K.; Gull, T.; Nielsen, K.; Pittard, J. M.

    2005-12-01

    We report on a series of X-ray spectra of the supermassive star Eta Carinae obtained by the High Energy Transmission Grating Spectrometer on the CHANDRA X-ray observatory before, during and after the star's X-ray minimum in the summer of 2003. The X-ray spectra show significant variations in emission measure and absorption, in the strength of the iron K edge and fluorescent iron emission, but show little change in the distribution of emission measure with temperature. The CHANDRA spectra also resolve emission from Si, S, Fe and other elements in H-like and He-like configurations. The HETGS spectra show that these lines change in centroid energy along with evidence of changes in the forbidden-to-intercombination ratios of the He-like triplets. These spectra offer strong support that the X-ray emission originates within a shock cone around an unseen, massive companion. The variations of the X-ray line spectrum provide a direct measure of the dynamics of the shocked gas in this cone and also evidence that the hottest region of the shock is not always in collisional ionization equilibrium. We discuss these results in light of the recent discovery of He II 4686 emission and the reported discovery of FUV emission from the companion star. This work was supported by SAO/Chandra grant GO3-4008A.

  13. Infrared studies of molecular shocks in the supernova remnant HB 21: II. Thermal admixture of shocked H2 gas in the south

    NASA Astrophysics Data System (ADS)

    Shinn, Jong-Ho; Koo, Bon-Chul; Burton, Michael; Lee, Ho-Gyu; Moon, Dae-Sik

    2010-02-01

    We present near- and mid-infrared observations on the shock-cloud interaction region in the southern part of the supernova remnant HB 21, performed with the InfraRed Camera (IRC) aboard AKARI satellite and the Wide InfraRed Camera (WIRC) at the Palomar 5 m telescope. The IRC 4 μm (N4), 7 μm (S7), and 11 μm (S11) band images and the WIRC Hυ=1→0S(1) 2.12 μm image show similar diffuse features, around a shocked CO cloud. We analyzed the emission through comparison with the H2 line emission of several shock models. The IRC colors are well explained by the thermal admixture model of H2 gas - whose infinitesimal H2 column density has a power-law relation with the temperature T, dN˜T-dT - with n(H)˜3.9×104cm-3,b˜4.2, and N(H;T>100K)˜2.8×1021cm-2. We interpreted these parameters with several different pictures of the shock-cloud interactions - multiple planar C-shocks, bow shocks, and shocked clumps - and discussed their weaknesses and strengths. The observed Hυ=1→0S(1) intensity is four times greater than the prediction from the power-law admixture model, the same tendency as found in the northern part of HB 21 (Paper I). We also explored the limitation of the thermal admixture model with respect to the derived model parameters.

  14. Shocks, Superbubbles, and Filaments: Investigations into Large Scale Gas Motions in Giant Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Pon, Andrew Richard

    2013-12-01

    Giant molecular clouds (GMCs), out of which stars form, are complex, dynamic systems, which both influence and are shaped by the process of star formation. In this dissertation, I examine three different facets of the dynamical motions within GMCs. Collapse modes in different dimensional objects. Molecular clouds contain lower dimensional substructures, such as filaments and sheets. The collapse properties of finite filaments and sheets differ from those of spherical objects as well as infinite sheets and filaments. I examine the importance of local collapse modes of small central perturbations, relative to global collapse modes, in different dimensional objects to elucidate whether strong perturbations are required for molecular clouds to fragment to form stars. I also calculate the dependence of the global collapse timescale upon the aspect ratio of sheets and filaments. I find that lower dimensional objects are more readily fragmented, and that for a constant density, lower dimensional objects and clouds with larger aspect ratios collapse more slowly. An edge-driven collapse mode also exists in sheets and filaments and is most important in elongated filaments. The failure to consider the geometry of a gas cloud is shown to lead to an overestimation of the star formation rate by up to an order of magnitude. Molecular tracers of turbulent energy dissipation. Molecular clouds contain supersonic turbulence that simulations predict will decay rapidly via shocks. I use shock models to predict which species emit the majority of the turbulent energy dissipated in shocks and find that carbon monoxide, CO, is primarily responsible for radiating away this energy. By combining these shock models with estimates for the turbulent energy dissipation rate of molecular clouds, I predict the expected shock spectra of CO from molecular clouds. I compare the results of these shock models to predictions for the emission from the unshocked gas in GMCs and show that mid

  15. Laser-Accelerated Ions from a Shock-Compressed Gas Foil

    NASA Astrophysics Data System (ADS)

    Helle, M. H.; Gordon, D. F.; Kaganovich, D.; Chen, Y.; Palastro, J. P.; Ting, A.

    2016-10-01

    We present results of energetic laser-ion acceleration from a tailored, near solid density gas target. Colliding hydrodynamic shocks compress a pure hydrogen gas jet into a 70 μ m thick target prior to the arrival of the ultraintense laser pulse. A density scan reveals the transition from a regime characterized by a wide angle, low-energy beam (target normal sheath acceleration) to one of a more focused beam with a high-energy halo (magnetic vortex acceleration). In the latter case, three-dimensional simulations show the formation of a Z pinch driven by the axial current resulting from laser wakefield accelerated electrons. Ions at the rear of the target are then accelerated by a combination of space charge fields from accelerated electrons and Coulombic repulsion as the pinch dissipates.

  16. Effects of xenon gas on generation and propagation of shock waves in the cavity of excimer laser

    NASA Astrophysics Data System (ADS)

    Kosugi, Shinichiroh; Maeno, Kazuo; Honma, Hiroki

    1993-05-01

    High repetition rate excimer lasers are expected for wide industrial application. The power of excimer laser, however, decreases rapidly in a higher repetition rate operation. Shock or acoustic waves, which are caused by the periodic pulse discharge, may limit the repetition rate of an excimer laser up to 2.5 kHz. Such waves cause inhomogeneity of gas density in the discharge region of the excimer laser. In high repetition rate operation this inhomogeneity remains at the next discharge. Arcing may be generated by this inhomogeneity and the homogeneous excitation of the laser gas is obstructed. Although these phenomena have been reported, the research for the effects of shock waves has remained insufficient. And the relation between these shock waves and discharge phenomena has not been clarified. To resolve this problem, we developed a scaling model chamber of a UV preionized excimer laser cavity with windows for flow visualization. We report the first result by using this model and Schlieren technique in a pure helium gas case. In our experiment three types of shock waves are found in the discharge cavity. Those shock waves are generated from the boundary of the main discharge area, from sparking pin gaps, and from the main electrode surfaces. In this study we focus on the effect of xenon gas on the generation and the propagation of shock waves. Components of the Xe-Cl excimer laser gas are helium, xenon, and hydrogen chloride. In those gases xenon has the largest molecular weight of 131.29. So we conclude xenon plays an important role in the shock wave propagation and in discharge phenomenon.

  17. Similarity solutions of a strong shock wave propagation in a mixture of a gas and dusty particles

    NASA Technical Reports Server (NTRS)

    Pai, S. I.; Menon, S.; Fan, Z. Q.

    1980-01-01

    The similarity solutions of a strong shock wave propagation in a mixture of a gas and small solid particles have been investigated. Similarity solution exists only when the shock is very strong and the surrounding medium is of a constant density and at rest and with negligible counterpressure. The non-dimensional fundamental equations are derived and studied. The results depend on three non-dimensional parameters; i.e. (1) the ratio of the specific heats of the gas, (2) the mass concentration of the solid particles in the mixture and (3) the ratio of the density of the solid to that of initial density of the gas. Numerical solutions for various values of these parameters are presented and discussed. The speeds of the shock wave front and its location with various energy releases are given.

  18. A Parametric Approach to Shape Field-Relevant Blast Wave Profiles in Compressed-Gas-Driven Shock Tube

    PubMed Central

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

    Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1–3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68–1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is

  19. A parametric approach to shape field-relevant blast wave profiles in compressed-gas-driven shock tube.

    PubMed

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

    Detonation of a high-explosive produces shock-blast wave, shrapnel, and gaseous products. While direct exposure to blast is a concern near the epicenter, shock-blast can affect subjects, even at farther distances. When a pure shock-blast wave encounters the subject, in the absence of shrapnels, fall, or gaseous products the loading is termed as primary blast loading and is the subject of this paper. The wave profile is characterized by blast overpressure, positive time duration, and impulse and called herein as shock-blast wave parameters (SWPs). These parameters in turn are uniquely determined by the strength of high explosive and the distance of the human subjects from the epicenter. The shape and magnitude of the profile determine the severity of injury to the subjects. As shown in some of our recent works (1-3), the profile not only determines the survival of the subjects (e.g., animals) but also the acute and chronic biomechanical injuries along with the following bio-chemical sequelae. It is extremely important to carefully design and operate the shock tube to produce field-relevant SWPs. Furthermore, it is vital to identify and eliminate the artifacts that are inadvertently introduced in the shock-blast profile that may affect the results. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs that can be used to control the blast profile; the results can be easily applied to many of the laboratory shock tubes. Further, replication of shock profile (magnitude and shape) can be related to field explosions and can be a standard in comparing results across different laboratories. Forty experiments are carried out by judiciously varying SAPs such as membrane thickness, breech length (66.68-1209.68 mm), measurement location, and type of driver gas (nitrogen, helium). The effects SAPs have on the resulting shock-blast profiles are shown. Also, the shock-blast profiles of a TNT explosion from ConWep software is compared

  20. Inertial-Fusion-Related Hydrodynamic Instabilities in a Spherical Gas Bubble Accelerated by a Planar Shock Wave

    SciTech Connect

    Niederhaus, John; Ranjan, Devesh; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo; Greenough, Jeff

    2005-05-15

    Experiments studying the compression and unstable growth of a dense spherical bubble in a gaseous medium subjected to a strong planar shock wave (2.8 < M < 3.4) are performed in a vertical shock tube. The test gas is initially contained in a free-falling spherical soap-film bubble, and the shocked bubble is imaged using planar laser diagnostics. Concurrently, simulations are carried out using a compressible hydrodynamics code in r-z axisymmetric geometry.Experiments and computations indicate the formation of characteristic vortical structures in the post-shock flow, due to Richtmyer-Meshkov and Kelvin-Helmholtz instabilities, and smaller-scale vortices due to secondary effects. Inconsistencies between experimental and computational results are examined, and the usefulness of the current axisymmetric approach is evaluated.

  1. Molecular gas in the Galactic center region. III. Probing shocks in molecular cores

    NASA Astrophysics Data System (ADS)

    Huettemeister, S.; Dahmen, G.; Mauersberger, R.; Henkel, C.; Wilson, T. L.; Martin-Pintado, J.

    1998-06-01

    Multiline observations of C(18) O and SiO isotopomers toward 33 molecular peaks in the Galactic center region, taken at the SEST, JCMT and HHT telescopes, are presented. The C(18) O presumably traces the total H_2 column density, while the SiO traces gas affected by shocks and high temperature chemistry. The J =2-> 1 line of SiO is seen only in few regions of the Galactic disk. This line is easily detected in all Galactic center sources observed. A comparison of the strength of the rare isotopomers (29) SiO and (30) SiO to the strength of the main isotopomer (28) SiO implies that the J = 2 -> 1 transition of (28) SiO is optically thick. The (29) Si/(30) Si isotope ratio of 1.6 in the Galactic center clouds is consistent with the terrestrial value. Large Velocity Gradient models show that the dense component (n_H_2 >= 10(4) \\percc) in typical molecular cores in the Galactic center is cool (\\TKIN ~ 25 K), contrary to what is usually found in Giant Molecular Clouds in the disk, where the densest cores are the hottest. High kinetic temperatures, > 100 K, known to exist from NH_3 studies, are only present at lower gas densities of a few 10(3) cm(-3) , where SiO is highly subthermally excited. Assuming that \\CEIO\\ traces all of the molecular gas, it is found that in all cases but one, SiO emission is compatible with arising in gas at higher density that is (presently) relatively cool. The relative abundance of SiO is typically 10(-9) , but differs significantly between individual sources. It shows a dependence on the position of the source within the Galactic center region. High abundances are found in those regions for which bar potential models predict a high likelihood for cloud-cloud collisions. These results can be used to relate the amount of gas that has encountered shocks within the last ~ 10(6) years to the large scale kinematics in the inner ~ 500 pc of the Galaxy. Based on observations obtained at the Swedish-ESO Submillimeter Telescope (SEST, Project C

  2. Propagation of a cylindrical shock wave in a mixture of a non-ideal gas and small solid particles under the action of monochromatic radiation

    NASA Astrophysics Data System (ADS)

    Sahu, Praveen Kumar; Nath, Gorakh

    2016-07-01

    Cylindrical shock wave in a dusty gas is discussed under the action of monochromatic radiation into stellar atmosphere with a constant intensity on unit area. The gas is assumed to be grey and opaque and shock to be transparent. The dusty gas is assumed to be a mixture of non-ideal gas and small solid particles. To obtain some essential features of the shock propagation, small solid particles are taken as pseudo-fluid and it is assumed that the equilibrium flow condition is maintained in the flow-field. The effects of variation of the parameters of the non-idealness of the gas, the mass concentration of solid particles in the mixture, the ratio of the density of solid particles to the initial density of the gas and the radiation parameter are investigated. It is shown that an increase in the parameters of the non-idealness of the gas and the radiation parameter have decaying effect on the shock waves; whereas with an increase in the ratio of the density of solid particles to the initial density of the gas the shock strength increases. It is found that an increase in the parameter non-idealness of the gas and the ratio of the density of solid particles to the initial density of the gas have opposite behaviour on fluid velocity, pressure and shock strength. Also, it is shown that an increase in the radiation parameter has effect to decrease the flow variables and the shock strength.

  3. On the gas temperature in the shocked circumstellar envelopes of pulsating stars. II. Shock induced condensation around R Coronae Borealis stars.

    NASA Astrophysics Data System (ADS)

    Woitke, P.; Goeres, A.; Sedlmayr, E.

    1996-09-01

    A physical mechanism is presented, which may be essential for the occasional onset of dust formation in the circumstellar envelopes of pulsating RCrB stars. We study the thermal energy balance, the chemistry and the nucleation in fixed fluid elements of the circumstellar envelopes around RCrB stars, which are periodically hit by strong shock waves caused by the stellar pulsation. Non-LTE radiative heating and cooling via free-free, bound-free and atomic line transitions and via rotational and ro-vibrational transitions of polar molecules is taken into account. After the heating and compression due to an outrunning shock, the considered fluid element first radiates away its excess of internal energy, and then re-expands according to the periodicity, which is a typical feature in such pulsating envelopes. This reexpansion causes adiabatic cooling. Within a particular range of the gas particle densities n__= 10^7...10^cm^-3^, this finally causes substantial lower gas temperatures than in radiative equilibrium. Thus, the preconditions for effective carbon nucleation (high densities and low gas temperatures for a sufficiently long time) may be temporarily present quite near to the photosphere of a pulsating RCrB star. The presented mechanism leads to gas temperatures as low as 1500K already outside of a radial distance of only 1.5-3R_*_, despite of the high effective temperatures of RCrB stars.

  4. Shocked POststarburst Galaxy Survey. II. The Molecular Gas Content and Properties of a Subset of SPOGs

    NASA Astrophysics Data System (ADS)

    Alatalo, Katherine; Lisenfeld, Ute; Lanz, Lauranne; Appleton, Philip N.; Ardila, Felipe; Cales, Sabrina L.; Kewley, Lisa J.; Lacy, Mark; Medling, Anne M.; Nyland, Kristina; Rich, Jeffrey A.; Urry, C. Meg

    2016-08-01

    We present CO(1-0) observations of objects within the Shocked POststarburst Galaxy Survey taken with the Institut de Radioastronomie Millimétrique 30 m single dish and the Combined Array for Research for Millimeter Astronomy interferometer. Shocked poststarburst galaxies (SPOGs) represent a transitioning population of galaxies, with deep Balmer absorption ({{EW}}{{H}δ }\\gt 5 {\\mathring{{A}}} ), consistent with an intermediate-age (A-star) stellar population, and ionized gas line ratios inconsistent with pure star formation. The CO(1-0) subsample was selected from SPOGs detected by the Wide-field Infrared Survey Explorer with 22 μm flux detected at a signal-to-noise ratio (S/N) > 3. Of the 52 objects observed in CO(1-0), 47 are detected with S/N > 3. A large fraction (37%-46% ± 7%) of our CO-SPOG sample were visually classified as morphologically disrupted. The H2 masses detected were between {10}8.7-10.8 {M}⊙ , consistent with the gas masses found in normal galaxies, though approximately an order of magnitude larger than the range seen in poststarburst galaxies. When comparing the 22 μm and CO(1-0) fluxes, SPOGs diverge from the normal star-forming relation, having 22 μm fluxes in excess of the relation by a factor of < {ɛ }{{MIR}}> ={4.91}-0.39+0.42, suggestive of the presence of active galactic nuclei (AGNs). The Na i D characteristics of CO-SPOGs show that it is likely that many of these objects host interstellar winds. Objects with large Na i D enhancements also tend to emit in the radio, suggesting possible AGN driving of neutral winds.

  5. Exploring Protostellar Winds with [OI]: Constraining models of shocked gas and PDR using L1551-IRS5

    NASA Astrophysics Data System (ADS)

    Green, Joel

    2015-10-01

    The formation of stars and planets requires a transfer of angular momentum by fast (v ~ 100 km/s) winds. The role of winds in dispersal of circumstellar envelopes of embedded protostars controlling the mass of the star/disk system, and in distributing dust in the disk (which is often already sedimented by the late protostar phase), is poorly understood but crucial to models of accretion and planet formation. Winds are seen only indirectly as the swept-up gas forms a molecular outflow with velocities of a few to 10s of km/s. Direct observation of winds from embedded protostars is difficult because the atomic lines that trace the particle flux are typically emitted at optical/UV wavelengths, where they are attenuated by the enveloping dust. The [OI] 63um fine structure emission line, the dominant coolant in shocked gas, should be an excellent tracer of the wind flux. Neutral oxygen should be produced in the shocked wind and [OI] provides a direct measure of the mass loss rate in the wind. However, photodissociation regions, where the UV flux from the star/disk system interacts with the outflow cavity wall, also produce [OI] and [CII] 158um. In order to properly estimate the mass loss rate, we require velocity-resolved line profiles to separate the contribution of PDRs from shocks. Shocked gas should be offset, while the gas in PDR will be close to the sound speed. We propose to use SOFIA-GREAT to answer the question: What are the properties of the shocks emitting the observed [OI] and [CII] lines? We will use the high spectral resolution of GREAT to measure the line profiles toward an embedded protostar, which shows features of strong shocks and is less affected by interstellar radiation: the well-characterized protostar L1551-IRS5 provides an ideal test environment.

  6. Shock propagation in the exhaust gas handling system of the proposed large altitude rocket cell: methods and preliminary analysis

    SciTech Connect

    Sutton, S.B.; Pierce, R.E.

    1984-10-04

    Numerical predictions are to be performed of the shock pressures that would result from the detonation of 100,000 lbm TNT. The initial phase of the project was to develop the methodology for analyzing the problem, develop a preliminary conceptual design to use in initial simulations, and estimate over-pressures, inside the conceptual facility, resulting from the propellant detonation. This report discusses the methods of analysis used to study the problem of the detonation of the propellant, and the propagation of the shock wave inside the exhaust gas processing system, and presents preliminary results. The KOVEC computer code was used to simulate the detonation of 100,000 lbm TNT and develop a boundary prescription for use in the gas dynamics code GASP which models the propagation of the shock wave through the LARC exhaust gas processing system. Results are presented showing the effect of cross-sectional area changes and variations in the initial pressure in the gas processing system on the shock wave peak pressure and propagation speed.

  7. Sampling and Analysis of the Headspace Gas in 3013 Type Plutonium Storage Containers at Los Alamos National Laboratory

    SciTech Connect

    Jackson, Jay M.; Berg, John M.; Hill, Dallas D.; Worl, Laura A.; Veirs, Douglas K.

    2012-07-11

    Department of Energy (DOE) sites have packaged approximately 5200 3013 containers to date. One of the requirements specified in DOESTD-3013, which specifies requirements for packaging plutonium bearing materials, is that the material be no greater than 0.5 weight percent moisture. The containers are robust, nested, welded vessels. A shelf life surveillance program was established to monitor these cans over their 50 year design life. In the event pressurization is detected by radiography, it will be necessary to obtain a head space gas sample from the pressurized container. This technique is also useful to study the head space gas in cans selected for random destructive evaluation. The atmosphere is sampled and the hydrogen to oxygen ratio is measured to determine the effects of radiolysis on the moisture in the container. A system capable of penetrating all layers of a 3013 container assembly and obtaining a viable sample of the enclosed gas and an estimate of internal pressure was designed.

  8. Internship at Los Alamos National Laboratory

    SciTech Connect

    Dunham, Ryan Q.

    2012-07-11

    Los Alamos National Laboratory (LANL) is located in Los Alamos, New Mexico. It provides support for our country's nuclear weapon stockpile as well as many other scientific research projects. I am an Undergraduate Student Intern in the Systems Design and Analysis group within the Nuclear Nonproliferation division of the Global Security directorate at LANL. I have been tasked with data analysis and modeling of particles in a fluidized bed system for the capture of carbon dioxide from power plant flue gas.

  9. Unsteady isothermal flow behind a magnetogasdynamic shock wave in a self-gravitating gas with exponentially varying density

    NASA Astrophysics Data System (ADS)

    Nath, G.

    2014-06-01

    The propagation of spherical (or cylindrical) shock wave in an ideal gas with or without gravitational effects in the presence of a constant azimuthal magnetic field is investigated. Non-similarity solutions are obtained for isothermal flow between the shock and the piston. The numerical solutions are obtained using the Runge-Kutta method of the fourth order. The density of the gas is assumed to be varying and obeying an exponential law. The shock wave moves with variable velocity, and the total energy of the wave is non-constant and varies with time. The effects of variation of the Alfven-Mach number, gravitational parameter and time are obtained. It is investigated that the presence of gravitational field reduces the effect of the magnetic field. Also, the presence of gravitational field increases the compressibility of the medium, due to which it is compressed and, therefore, the distance between the inner contact surface and the shock surface is reduced. The shock waves in conducting perfect gas can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, nuclear explosion, rupture of a pressurized vessel and explosion in the ionosphere. Other potential applications of this study include analysis of data from exploding wire experiments and cylindrically symmetric hypersonic flow problems associated with meteors or re-entry vehicles etc. A comparison is made between the solutions in the cases of the gravitating and the non-gravitating medium with or without magnetic field. The obtained solutions are applicable for arbitrary values of time.

  10. Experimental measurements of time dependent structure in shock waves and gravitational-collapse of a granular gas

    NASA Astrophysics Data System (ADS)

    Voth, Greg A.; Perez, John A.; Son, Reuben

    2009-06-01

    We experimentally measure time-dependent velocity statistics in a quasi-2D granular gas under gravity. High resolution video particle tracking measurements show that the vibration induced shock waves have a serrated substructure on the scale of a particle diameter. We identify this substructure as an experimental visualization of collisional transport. Collisional transport is non-local in granular variables and is the mechanism for increased sound speed at higher densities. We also measure the time-dependent statistical properties of the gas after the energy input has been halted. The cooling occurs in two distinct stages separated by a high temperature settling shock. In the final stage, the temperature of a fluid packet decreases as a power law until the gas reaches a static state in agreement with recent theoretical work on this problem. However, the measured power law exponent is significantly larger than the theoretical value.

  11. Flow Visualization and Measurements of the Mixing Evolution of a Shock-Accelerated Gas Curtain

    SciTech Connect

    Prestridge, K.; Vorobieff, P.V.; Rightley, P.M.; Benjamin, R.F

    1999-07-19

    We describe a highly-detailed experimental characterization of the impulsively driven Rayleigh-Taylor instability, called the Richtmyer-Meshkov instability. This instability is produced by flowing a diffuse, vertical curtain of heavy gas (SF{sub 6}) into the test section of an air-filled horizontally oriented shock tube. The instability evolves after the passage of a Mach 1.2 shock past the curtain, and the development of the curtain is visualized by seeding the SF{sub 6} with small (d{approximately}0.5 and micro;m) glycol droplets using a modified theatrical fog generator. Because the event lasts only 1 ms and the initial conditions vary from test to test, rapid and complete data acquisition is required in order to characterize the initial and dynamic conditions for each experimental shot. Through the use of a custom-built pulsed Nd: YAG laser, we are able to image the flowfield at seven different times. We acquire a double-pulsed image of the flow with the use of a second pulsed Nd:YAG, which is used to determine the instantaneous velocity field using Particle Image Velocimetry (PIV). During a single experiment, high resolution images of the initial conditions and dynamic conditions are acquired using three CCD cameras. Issues of the fidelity of the flow seeding technique and the reliability of the PIV technique will be addressed. We have successfully provided interesting data through analysis of the images alone, and we are hoping that PIV information will be able to add further physical insight to the evolution of the RM instability and the transition to turbulence.

  12. ORTHO-TO-PARA RATIO STUDIES OF SHOCKED H{sub 2} GAS IN THE TWO SUPERNOVA REMNANTS IC 443 AND HB 21

    SciTech Connect

    Shinn, Jong-Ho; Moon, Dae-Sik; Lee, Ho-Gyu E-mail: hglee@astron.s.u-tokyo.ac.jp

    2012-11-01

    We present near-infrared (2.5-5.0 {mu}m) spectral studies of shocked H{sub 2} gas in two supernova remnants, IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with the Infrared Camera aboard the AKARI satellite. At the energy range 7000 K {approx}< E({upsilon},J) {approx}< 20,000 K, the shocked H{sub 2} gas in IC 443 shows an ortho-to-para ratio (OPR) of 2.4{sup +0.3} {sub -0.2}, which is significantly lower than the equilibrium value 3, suggesting the existence of non-equilibrium OPR. The shocked gas in HB 21 also indicates a potential non-equilibrium OPR in the range of 1.8-2.0. The level populations are well described by the power-law thermal admixture model with a single OPR, where the temperature integration range is 1000-4000 K. We conclude that the obtained non-equilibrium OPR probably originates from the reformed H{sub 2} gas of dissociative J-shocks, considering several factors such as the shock combination requirement, the line ratios, and the possibility that H{sub 2} gas can form on grains with a non-equilibrium OPR. We also investigate C-shocks and partially dissociative J-shocks as the origin of the non-equilibrium OPR. However, we find that they are incompatible with the observed ionic emission lines for which dissociative J-shocks are required to explain. The difference in the collision energy of H atoms on grain surfaces would give rise to the observed difference between the OPRs of IC 443 and HB 21, if dissociative J-shocks are responsible for the H{sub 2} emission. Our study suggests that dissociative J-shocks can produce shocked H{sub 2} gas with a non-equilibrium OPR.

  13. Flow behind an exponential shock wave in a rotational axisymmetric perfect gas with magnetic field and variable density.

    PubMed

    Nath, G; Sahu, P K

    2016-01-01

    A self-similar model for one-dimensional unsteady isothermal and adiabatic flows behind a strong exponential shock wave driven out by a cylindrical piston moving with time according to an exponential law in an ideal gas in the presence of azimuthal magnetic field and variable density is discussed in a rotating atmosphere. The ambient medium is assumed to possess radial, axial and azimuthal component of fluid velocities. The initial density, the fluid velocities and magnetic field of the ambient medium are assumed to be varying with time according to an exponential law. The gas is taken to be non-viscous having infinite electrical conductivity. Solutions are obtained, in both the cases, when the flow between the shock and the piston is isothermal or adiabatic by taking into account the components of vorticity vector. The effects of the variation of the initial density index, adiabatic exponent of the gas and the Alfven-Mach number on the flow-field behind the shock wave are investigated. It is found that the presence of the magnetic field have decaying effects on the shock wave. Also, it is observed that the effect of an increase in the magnetic field strength is more impressive in the case of adiabatic flow than in the case of isothermal flow. The assumption of zero temperature gradient brings a profound change in the density, non-dimensional azimuthal and axial components of vorticity vector distributions in comparison to those in the case of adiabatic flow. A comparison is made between isothermal and adiabatic flows. It is obtained that an increase in the initial density variation index, adiabatic exponent and strength of the magnetic field decrease the shock strength. PMID:27652082

  14. Flow behind an exponential shock wave in a rotational axisymmetric perfect gas with magnetic field and variable density.

    PubMed

    Nath, G; Sahu, P K

    2016-01-01

    A self-similar model for one-dimensional unsteady isothermal and adiabatic flows behind a strong exponential shock wave driven out by a cylindrical piston moving with time according to an exponential law in an ideal gas in the presence of azimuthal magnetic field and variable density is discussed in a rotating atmosphere. The ambient medium is assumed to possess radial, axial and azimuthal component of fluid velocities. The initial density, the fluid velocities and magnetic field of the ambient medium are assumed to be varying with time according to an exponential law. The gas is taken to be non-viscous having infinite electrical conductivity. Solutions are obtained, in both the cases, when the flow between the shock and the piston is isothermal or adiabatic by taking into account the components of vorticity vector. The effects of the variation of the initial density index, adiabatic exponent of the gas and the Alfven-Mach number on the flow-field behind the shock wave are investigated. It is found that the presence of the magnetic field have decaying effects on the shock wave. Also, it is observed that the effect of an increase in the magnetic field strength is more impressive in the case of adiabatic flow than in the case of isothermal flow. The assumption of zero temperature gradient brings a profound change in the density, non-dimensional azimuthal and axial components of vorticity vector distributions in comparison to those in the case of adiabatic flow. A comparison is made between isothermal and adiabatic flows. It is obtained that an increase in the initial density variation index, adiabatic exponent and strength of the magnetic field decrease the shock strength.

  15. Shocked and Scorched: Free-Floating Evaporating Gas Globules and Star Formation in Cygnus

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra; Claussen, M. J.; Morris, M. R.

    2012-05-01

    We report molecular line observations of a new class of Free-floating Evaporating Gas Globules with tadpole shapes (i.e., FrEGGs), recently discovered in the Cygnus star-forming region. We serendipitously found two of these in an HST imaging survey, including one of the most prominent members of this class (IRAS20324+4057: the Tadpole). Our molecular-line observations, carried out with the Arizona Radio Observatory's mm-wave telescopes, include on-the-fly maps in the CO and 13CO J=2-1 lines as well as pointed observations in the J=3-2 line of the high-density tracers HCO+ and N2H+. These data show the presence of dense molecular cores with total masses of cold molecular gas exceeding one to a few Msun in almost all FrEGGs. Our radio continuum imaging of 3 FrEGGs, as well as Halpha images from the IPHAS survey reveal bright photo-ionized peripheries around these objects. We infer that FrEGGs are dense, star-forming molecular cores that originated in the Cygnus cloud and are now being photoevaporated by the ultraviolet radiation field of the Cyg OB2 cluster, and shaped by the ram pressure of strong wind sources. The extended tails in some of the largest objects show wiggles likely resulting from Kelvin-Helmoltz instabilities. We find evidence for non-thermal radio emission in the Tadpole, with the radio emission peaking strongly along the shock/ionization front at its head, possibly as a result of a compressed magnetic layer in this front that is interacting with cosmic rays associated with the Cyg OB2 association.

  16. Chemically Distinct Nuclei and Outflowing Shocked Molecular Gas in Arp 220

    NASA Astrophysics Data System (ADS)

    Tunnard, R.; Greve, T. R.; Garcia-Burillo, S.; Graciá Carpio, J.; Fischer, J.; Fuente, A.; González-Alfonso, E.; Hailey-Dunsheath, S.; Neri, R.; Sturm, E.; Usero, A.; Planesas, P.

    2015-02-01

    We present the results of interferometric spectral line observations of Arp 220 at 3.5 mm and 1.2 mm from the Plateau de Bure Interferometer, imaging the two nuclear disks in H13CN(1-0) and (3-2), H13CO+(1-0) and (3-2), and HN13C(3-2) as well as SiO(2-1) and (6-5), HC15N(3-2), and SO(66-55). The gas traced by SiO(6-5) has a complex and extended kinematic signature including a prominent P Cygni profile, almost identical to previous observations of HCO+(3-2). Spatial offsets 0.''1 north and south of the continuum center in the emission and absorption of the SiO(6-5) P Cygni profile in the western nucleus (WN) imply a bipolar outflow, delineating the northern and southern edges of its disk and suggesting a disk radius of ~40 pc, consistent with that found by ALMA observations of Arp 220. We address the blending of SiO(6-5) and H13CO+(3-2) by considering two limiting cases with regards to the H13CO+ emission throughout our analysis. Large velocity gradient modeling is used to constrain the physical conditions of the gas and to infer abundance ratios in the two nuclei. Our most conservative lower limit on the [H13CN]/[H13CO+] abundance ratio is 11 in the WN, compared with 0.10 in the eastern nucleus (EN). Comparing these ratios to the literature we argue on chemical grounds for an energetically significant active galactic nucleus in the WN driving either X-ray or shock chemistry, and a dominant starburst in the EN.

  17. Mass spectrometer measurements of test gas composition in a shock tunnel

    NASA Technical Reports Server (NTRS)

    Skinner, K. A.; Stalker, R. J.

    1995-01-01

    Shock tunnels afford a means of generating hypersonic flow at high stagnation enthalpies, but they have the disadvantage that thermochemical effects make the composition of the test flow different to that of ambient air. The composition can be predicted by numerical calculations of the nozzle flow expansion, using simplified thermochemical models and, in the absence of experimental measurements, it has been necessary to accept the results given by these calculations. This note reports measurements of test gas composition, at stagnation enthalpies up to 12.5 MJ.kg(exp -1), taken with a time-of-flight mass spectrometer. Limited results have been obtained in previous measurements. These were taken at higher stagnation enthalpies, and used a quadruple mass spectrometer. The time-of-flight method was preferred here because it enabled a number of complete mass spectra to be obtained in each test, and because it gives good mass resolution over the range of interest with air (up to 50 a.m.a.).

  18. Numerical modeling of chemistry and gas dynamics during shock-induced ethylene combustion

    SciTech Connect

    Clifford, L.J.; Milne, A.M.; Murray, B.A.

    1996-02-01

    The authors present the results of a numerical study of shock-induced ethylene combustion. They compare the accuracy and efficiency of a variety of methods when applied to this combustion problem. For a full kinetics scheme they consider the speed of a range of alternative ordinary differential equation solvers. They find that for the coupled ODE-hydrodynamic problem an extrapolated linearly implicit Euler method is the fastest of the methods used, but that otherwise a fourth-order Rosenbrock scheme is the fastest solution method. The identity of the fastest method changes because of the start up conditions having to be recalculated at the start of every step in a coupled ODE-hydrodynamics module. The authors then apply a detailed reduction strategy to a chemical kinetics reaction data set and find that it cannot be reduced by many reactions as it is already a fairly compact set. They then introduce an induction parameter model based on the two parameter model of Taki and Fujiwara and the work of Oran et al. They derive functions that model the induction times and the energy release rates predicted using the chemical kinetics data set. They show some results of coupled gas dynamics and reactive flow calculations using these models and compare with experiment. They find that the induction parameter model reproduces the experimental results well while using less than 5% of the computational time of the chemical kinetics model.

  19. Environmental Assessment and Finding of No Significant Impact: The Proposed Issuance of an Easement to Public Service Company of New Mexico for the Construction and Operation of a 12-inch Natural Gas Pipeline within Los Alamos National Laboratory, Los Alamos, New Mexico

    SciTech Connect

    N /A

    2002-07-30

    The National Nuclear Security Administration (NNSA) has assigned a continuing role to Los Alamos National Laboratory (LANL) in carrying out NNSAs national security mission. To enable LANL to continue this enduring responsibility requires that NNSA maintain the capabilities and capacities required in support of its national mission assignments at LANL. To carry out its Congressionally assigned mission requirements, NNSA must maintain a safe and reliable infrastructure at LANL. Upgrades to the various utility services at LANL have been ongoing together with routine maintenance activities over the years. However, the replacement of a certain portion of natural gas service transmission pipeline is now necessary as this delivery system element has been operating well beyond its original design life for the past 20 to 30 years and components of the line are suffering from normal stresses, strains, and general failures. The Proposed Action is to grant an easement to the Public Service Company of New Mexico (PNM) to construct, operate, and maintain approximately 15,000 feet (4,500 meters) of 12-inch (in.) (30-centimeter [cm]) coated steel natural gas transmission mainline on NNSA-administered land within LANL along Los Alamos Canyon. The new gas line would begin at the existing valve setting located at the bottom of Los Alamos Canyon near the Los Alamos County water well pump house and adjacent to the existing 12-in. (30-cm) PNM gas transmission mainline. The new gas line (owned by PNM) would then cross the streambed and continue east in a new easement obtained by PNM from the NNSA, paralleling the existing electrical power line along the bottom of the canyon. The gas line would then turn northeast near State Road (SR) 4 and be connected to the existing 12-in. (30-cm) coated steel gas transmission mainline, located within the right-of-way (ROW) of SR 502. The Proposed Action would also involve crossing a streambed twice. PNM would bore under the streambed for pipe

  20. Experimental and numerical investigation of shock wave propagation through complex geometry, gas continuous, two-phase media

    SciTech Connect

    Chien-Chih Liu, J.

    1993-12-31

    The work presented here investigates the phenomenon of shock wave propagation in gas continuous, two-phase media. The motivation for this work stems from the need to understand blast venting consequences in the HYLIFE inertial confinement fusion (ICF) reactor. The HYLIFE concept utilizes lasers or heavy ion beams to rapidly heat and compress D-T targets injected into the center of a reactor chamber. A segmented blanket of falling molten lithium or Li{sub 2}BeF{sub 4} (Flibe) jets encircles the reactor`s central cavity, shielding the reactor structure from radiation damage, absorbing the fusion energy, and breeding more tritium fuel. X-rays from the fusion microexplosion will ablate a thin layer of blanket material from the surfaces which face toward the fusion site. This generates a highly energetic vapor, which mostly coalesces in the central cavity. The blast expansion from the central cavity generates a shock which propagates through the segmented blanket - a complex geometry, gas-continuous two-phase medium. The impulse that the blast gives to the liquid as it vents past, the gas shock on the chamber wall, and ultimately the liquid impact on the wall are all important quantities to the HYLIFE structural designers.

  1. Experimental and Numerical Investigation of Shock Wave Propagation Through Complex Geometry, Gas Continuous, Two-Phase Media

    NASA Astrophysics Data System (ADS)

    Liu, James Chien-Chih

    The work presented here investigates the phenomenon of shock wave propagation in gas continuous, two-phase media. The motivation for this work stems from the need to understand blast venting consequences in the HYLIFE inertial confinement fusion (ICF) reactor. The HYLIFE concept utilizes lasers or heavy ion beams to rapidly heat and compress D-T targets injected into the center of a reactor chamber. A segmented blanket of falling molten lithium or Li_2BeF_4 (Flibe) jets encircles the reactor's central cavity, shielding the reactor structure from radiation damage, absorbing the fusion energy, and breeding more tritium fuel. Xrays from the fusion microexplosion will ablate a thin layer of blanket material from the surfaces which face toward the fusion site. This generates a highly energetic vapor, which mostly coalesces in the central cavity. The blast expansion from the central cavity generates a shock which propagates through the segmented blanket--a complex geometry, gas-continuous two-phase medium. The impulse that the blast gives to the liquid as it vents past, the gas shock on the chamber wall, and ultimately the liquid impact on the wall are all important quantities to the HYLIFE structural designers. The work here presents a numerical method called the Transient Shockwave Upwind Numerical Analysis Method for ICF (TSUNAMI). It is a tool for analyzing two-dimensional blast venting in the HYLIFE reactor. TSUNAMI relies on the assumptions of adiabatic and ideal gas behavior by the vapor and immobile liquid to simplify the problem of two-phase shock propagation to a problem of single phase gas dynamics in a fixed, complex geometry. To validate the accuracy of the numerical method, experimental data for comparison was obtained from the Liquid Jet Array Shock Tube (LJAST). The experiment provided transient pressure data for gas shocks impacting an array of solid cylinders and an array of liquid jets with similar geometry to the HYLIFE blanket. The comparisons showed

  2. Simulations of FY15 2-shock CH Campaign Shots

    NASA Astrophysics Data System (ADS)

    Bradley, Paul; Peterson, R. R.; Yin, L.; Olson, R. E.; Kline, J. L.; Krasheninnikova, N. S.; MacLaren, S. A.; Ma, T.; Salmonson, J. D.; Kyrala, G. A.; Pino, J.; Dewald, E.; Khan, S.; Sayre, D.; Tommasini, R.; Ralph, J.; Turnbull, D.

    2015-11-01

    The 2-shock campaign is a joint Los Alamos/Livermore project to investigate the role of shock timing, asymmetry, and shock convergence on the performance of ICF capsules. This campaign uses a simple two step pulse that makes it easier to correlate the effect of changing the laser pulse on the performance of the capsule. The ~ 680 micron outer radius capsule has a CH or CH +1 at% Si ablator approximately 175 microns thick surrounding the gas region that is either D2 or THD gas at 0.0085 g/cc. The capsules are indirectly driven inside a gold hohlraum that is 9.2 mm long by 5.75 mm in diameter. The three CD inner surface capsules utilized THD fuel so that the DT yield would arise from mixing of CD shell material into the tritium of the gas region. Our simulated results compare well to the experimental yield, ion temperature, burn width, x-ray size, and radius versus time data. Work performed by Los Alamos National Laboratory under contract DE-AC52-06NA25396 for the National Nuclear Security Administration of the U.S. Department of Energy.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  4. Preheated light gas gun shock experiments: hot Molybdenum and diopside-anorthite liquid Hugoniots revisited

    NASA Astrophysics Data System (ADS)

    Asimow, P. D.; Sun, D.; Ahrens, T. J.

    2006-12-01

    We have extended the techniques for pre-heated Hugoniot equation of state measurements for use on Caltech's 25 mm light gas gun at flyer velocities up to 7.5 km/s. Previous data on Mo at 1400°C and on a variety of silicate liquids were collected on a 40 mm propellant gun up to a maximum flyer velocity of 2.6 km/s. Higher impact velocities open up a range of new opportunities, including tests of previous extrapolations of low-pressure data and direct probing of the properties of molten silicates at lower mantle pressure. Our preheated liquid experiments are conducted in sealed Mo capsules and therefore we need to know the Hugoniot of Mo initially at elevated temperature, which may differ by several percent from the principal Hugoniot of Mo. Miller et al. [1] measured the Hugoniot EOS of Mo initially at 1400°C up to a particle velocity (Up) of 1.5 km/s and applied a linear fit with shock velocities slower than the principal Hugoniot in the measured range, but implying a crossover when extrapolated above 1.8 km/s (i.e., about 100 GPa pressure). Molodets [2] fit these data to a parameter-free theoretical form for the volume dependence of the Grüneisen parameter that predicts a concave-downward high-temperature Hugoniot that runs below and approaches parallel with the principal Hugoniot. Our data point at Up = 2.5 km/s (204 GPa) is coincident with Molodet's theory within error. However, our data point at Up = 3.24 km/s (302 GPa) is not; we are investigating this discrepancy. The silicate liquid composition consisting of 64 mol % anorthite and 36 mol % diopside is a simplified analogue for basalt and was chosen for study by Rigden et al. [3]. This earlier study found the expected linear Us-Up Hugoniot (with molar volume intermediate between anorthite and diopside end members) up to 25 GPa, followed by two data points that suggested a dramatic stiffening to a nearly incompressible Hugoniot. We now have three experiments at higher pressure (44, 81, and 110 GPa) that

  5. Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

    SciTech Connect

    Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T.

    2013-12-15

    Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.

  6. Shocked Gas from the supernova remnant G357.7+0.3

    NASA Astrophysics Data System (ADS)

    Rho, Jeonghee; Hewitt, John; Reach, William T.; Bieging, John H.; Andersen, Morten; Güsten, Rolf

    2016-01-01

    We present detection of hydrogen molecular hydrogen (H2) in mid-infrared using the Spitzer IRS. The supernova remnant (SNR) G357.7+0.3 is one of relatively unknown and under-studied SNRs. We performed an IRS spectral mapping centered on the northwestern shell of G357.7+0.3. The observations covered an area of 75arcsec x 60arcsec with short-low (SL) and 170arcsec x 55arcsec with long-low (LL). All rotational H2 lines within the IRS wavelength range are detected except S(6) line. Interestingly, G357.7+0.3 shows lack of ionic lines compared with those in other SNRs observed. Only ionic line detected is [Si II] at 34.8micron. The detection of H2 line is an evidence that G357.7+0.3 is interacting with dense molecular clouds. This is the first evidence showing that G357.7+0.3 is an interacting SNR with clouds. We generated a H2 excitation diagram. A two-temperature fit yields a low temperature of 197 K with a column density 2.3E21/cm2 and and a high temperature of 663 K with a column density of 2.7E19/cm2. We preformed high-J CO and OH observations with The German REceiver for Astronomy at Terahertz Frequencies (GREAT) on board of Stratospheric Observatory for Infrared Astronomy (SOFIA), but no lines are detected. We provide the upper limits of the lines. We also present millimeter observations of the SNR. The observations were made with the Arizona-MPIfR Heinrich Hertz Submillimeter Telescope (HHT), Arizona 12 Meter Telescope, and Atacama Pathfinder Experiment (APEX) Telescope. We discuss physical conditions of shocked gas in G357.7+0.3.

  7. Interaction of a weak shock wave with a discontinuous heavy-gas cylinder

    SciTech Connect

    Wang, Xiansheng; Yang, Dangguo; Wu, Junqiang; Luo, Xisheng

    2015-06-15

    The interaction between a cylindrical inhomogeneity and a weak planar shock wave is investigated experimentally and numerically, and special attention is given to the wave patterns and vortex dynamics in this scenario. A soap-film technique is realized to generate a well-controlled discontinuous cylinder (SF{sub 6} surrounded by air) with no supports or wires in the shock-tube experiment. The symmetric evolving interfaces and few disturbance waves are observed in a high-speed schlieren photography. Numerical simulations are also carried out for a detailed analysis. The refracted shock wave inside the cylinder is perturbed by the diffracted shock waves and divided into three branches. When these shock branches collide, the shock focusing occurs. A nonlinear model is then proposed to elucidate effects of the wave patterns on the evolution of the cylinder. A distinct vortex pair is gradually developing during the shock-cylinder interaction. The numerical results show that a low pressure region appears at the vortex core. Subsequently, the ambient fluid is entrained into the vortices which are expanding at the same time. Based on the relation between the vortex motion and the circulation, several theoretical models of circulation in the literature are then checked by the experimental and numerical results. Most of these theoretical circulation models provide a reasonably good prediction of the vortex motion in the present configuration.

  8. Interaction of a weak shock wave with a discontinuous heavy-gas cylinder

    NASA Astrophysics Data System (ADS)

    Wang, Xiansheng; Yang, Dangguo; Wu, Junqiang; Luo, Xisheng

    2015-06-01

    The interaction between a cylindrical inhomogeneity and a weak planar shock wave is investigated experimentally and numerically, and special attention is given to the wave patterns and vortex dynamics in this scenario. A soap-film technique is realized to generate a well-controlled discontinuous cylinder (SF6 surrounded by air) with no supports or wires in the shock-tube experiment. The symmetric evolving interfaces and few disturbance waves are observed in a high-speed schlieren photography. Numerical simulations are also carried out for a detailed analysis. The refracted shock wave inside the cylinder is perturbed by the diffracted shock waves and divided into three branches. When these shock branches collide, the shock focusing occurs. A nonlinear model is then proposed to elucidate effects of the wave patterns on the evolution of the cylinder. A distinct vortex pair is gradually developing during the shock-cylinder interaction. The numerical results show that a low pressure region appears at the vortex core. Subsequently, the ambient fluid is entrained into the vortices which are expanding at the same time. Based on the relation between the vortex motion and the circulation, several theoretical models of circulation in the literature are then checked by the experimental and numerical results. Most of these theoretical circulation models provide a reasonably good prediction of the vortex motion in the present configuration.

  9. CHEMICALLY DISTINCT NUCLEI AND OUTFLOWING SHOCKED MOLECULAR GAS IN Arp 220

    SciTech Connect

    Tunnard, R.; Greve, T. R.; Garcia-Burillo, S.; Fuente, A.; Usero, A.; Planesas, P.; Carpio, J. Graciá; Hailey-Dunsheath, S.; Sturm, E.; Fischer, J.; González-Alfonso, E.; Neri, R.

    2015-02-10

    We present the results of interferometric spectral line observations of Arp 220 at 3.5 mm and 1.2 mm from the Plateau de Bure Interferometer, imaging the two nuclear disks in H{sup 13}CN(1-0) and (3-2), H{sup 13}CO{sup +}(1-0) and (3-2), and HN{sup 13}C(3-2) as well as SiO(2-1) and (6-5), HC{sup 15}N(3-2), and SO(6{sub 6}-5{sub 5}). The gas traced by SiO(6-5) has a complex and extended kinematic signature including a prominent P Cygni profile, almost identical to previous observations of HCO{sup +}(3-2). Spatial offsets 0.''1 north and south of the continuum center in the emission and absorption of the SiO(6-5) P Cygni profile in the western nucleus (WN) imply a bipolar outflow, delineating the northern and southern edges of its disk and suggesting a disk radius of ∼40 pc, consistent with that found by ALMA observations of Arp 220. We address the blending of SiO(6-5) and H{sup 13}CO{sup +}(3-2) by considering two limiting cases with regards to the H{sup 13}CO{sup +} emission throughout our analysis. Large velocity gradient modeling is used to constrain the physical conditions of the gas and to infer abundance ratios in the two nuclei. Our most conservative lower limit on the [H{sup 13}CN]/[H{sup 13}CO{sup +}] abundance ratio is 11 in the WN, compared with 0.10 in the eastern nucleus (EN). Comparing these ratios to the literature we argue on chemical grounds for an energetically significant active galactic nucleus in the WN driving either X-ray or shock chemistry, and a dominant starburst in the EN.

  10. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Radial Gas Inflow and Shock Excitation in NGC 1042

    NASA Astrophysics Data System (ADS)

    Luo, Rongxin; Hao, Lei; Blanc, Guillermo A.; Jogee, Shardha; van den Bosch, Remco C. E.; Weinzirl, Tim

    2016-06-01

    NGC 1042 is a late-type bulgeless disk galaxy that hosts low-luminosity active galactic nuclei (AGNs) coincident with a massive nuclear star cluster. In this paper, we present the integral field spectroscopy studies of this galaxy, based on the data obtained with the Mitchell spectrograph on the 2.7 m Harlan J. Smith telescope. In the central 100-300 pc region of NGC 1042, we find a circumnuclear ring structure of gas with enhanced ionization, which we suggest is mainly induced by shocks. Combining this with the harmonic decomposition analysis of the velocity field of the ionized gas, we propose that the shocked gas is the result of gas inflow driven by the inner spiral arms. The inflow velocity is ˜ 32+/- 10 {km} {{{s}}}-1, and the estimated mass-inflow rate is ˜ 1.1+/- 0.3× {10}-3 {M}⊙ {{yr}}-1. The mass-inflow rate is about one hundred times the black hole’s mass-accretion rate (˜ 1.4× {10}-5 {M}⊙ {{yr}}-1) and slightly larger than the star-formation rate in the nuclear star cluster (7.94× {10}-4 {M}⊙ {{yr}}-1), implying that the inflow material is enough to feed both the AGN activity and star formation in the nuclear star cluster. Our study highlights that secular evolution can be important in late-type unbarred galaxies like NGC 1042.

  11. The VIRUS-P Exploration of Nearby Galaxies (VENGA): Radial Gas Inflow and Shock Excitation in NGC 1042

    NASA Astrophysics Data System (ADS)

    Luo, Rongxin; Hao, Lei; Blanc, Guillermo A.; Jogee, Shardha; van den Bosch, Remco C. E.; Weinzirl, Tim

    2016-06-01

    NGC 1042 is a late-type bulgeless disk galaxy that hosts low-luminosity active galactic nuclei (AGNs) coincident with a massive nuclear star cluster. In this paper, we present the integral field spectroscopy studies of this galaxy, based on the data obtained with the Mitchell spectrograph on the 2.7 m Harlan J. Smith telescope. In the central 100–300 pc region of NGC 1042, we find a circumnuclear ring structure of gas with enhanced ionization, which we suggest is mainly induced by shocks. Combining this with the harmonic decomposition analysis of the velocity field of the ionized gas, we propose that the shocked gas is the result of gas inflow driven by the inner spiral arms. The inflow velocity is ˜ 32+/- 10 {km} {{{s}}}-1, and the estimated mass-inflow rate is ˜ 1.1+/- 0.3× {10}-3 {M}ȯ {{yr}}-1. The mass-inflow rate is about one hundred times the black hole’s mass-accretion rate (˜ 1.4× {10}-5 {M}ȯ {{yr}}-1) and slightly larger than the star-formation rate in the nuclear star cluster (7.94× {10}-4 {M}ȯ {{yr}}-1), implying that the inflow material is enough to feed both the AGN activity and star formation in the nuclear star cluster. Our study highlights that secular evolution can be important in late-type unbarred galaxies like NGC 1042.

  12. C IV and He II line emission of Lyman α blobs: powered by shock-heated gas

    NASA Astrophysics Data System (ADS)

    Cabot, Samuel H. C.; Cen, Renyue; Zheng, Zheng

    2016-10-01

    Utilizing ab initio ultrahigh resolution hydrodynamical simulations, we investigate the properties of the interstellar and circumgalactic medium of Lyα blobs (LABs) at z = 3, focusing on three important emission lines: Lyα 1216 Å, He II 1640 Å and C IV 1549 Å. Their relative strengths provide a powerful probe of the thermodynamic properties of the gas when confronted with observations. By adjusting the dust attenuation effect using one parameter and matching the observed size-luminosity relation of LABs using another parameter, we show that our simulations can reproduce the observed C IV/Lyα and He II/Lyα ratios adequately. This analysis provides the first successful physical model to account for simultaneously the LAB luminosity function, luminosity-size relation and the C IV/Lyα and He II/Lyα ratios, with only two parameters. The physical underpinning for this model is that, in addition to the stellar component for the Lyα emission, the Lyα and C IV emission lines due to shock-heated gas are primarily collisional excitation driven and the He II emission line collisional ionization driven. We find that the density, temperature and metallicity of the gas responsible for each emission line is significantly distinct, in a multiphase interstellar and circumgalactic medium that is shock heated primarily by supernovae and secondarily by gravitational accretion of gas.

  13. 1D GAS-DYNAMIC SIMULATION OF SHOCK-WAVE PROCESSES VIA INTERNET

    SciTech Connect

    Khishchenko, K. V.; Levashov, P. R.; Povarnitsyn, M. E.; Zakharenkov, A. S.

    2009-12-28

    We present a Web-interface for 1D simulation of different shock-wave experiments. The choosing of initial parameters, the modeling itself and output data treatment can be made directly via the Internet. The interface is based upon the expert system on shock-wave data and equations of state and contains both the Eulerian and Lagrangian Godunov hydrocodes. The availability of equations of state for a broad set of substances makes this system a useful tool for planning and interpretation of shock-wave experiments. As an example of simulation with the system, results of modeling of multistep shock loading of potassium between polytetrafluoroethylene and stainless steel plates are presented in comparison with experimental data from Shakhray et al.(2005).

  14. D Gas-Dynamic Simulation of Shock-Wave Processes via Internet

    NASA Astrophysics Data System (ADS)

    Khishchenko, K. V.; Levashov, P. R.; Povarnitsyn, M. E.; Zakharenkov, A. S.

    2009-12-01

    We present a Web-interface for 1D simulation of different shock-wave experiments. The choosing of initial parameters, the modeling itself and output data treatment can be made directly via the Internet. The interface is based upon the expert system on shock-wave data and equations of state and contains both the Eulerian and Lagrangian Godunov hydrocodes. The availability of equations of state for a broad set of substances makes this system a useful tool for planning and interpretation of shock-wave experiments. As an example of simulation with the system, results of modeling of multistep shock loading of potassium between polytetrafluoroethylene and stainless steel plates are presented in comparison with experimental data from Shakhray et al. (2005).

  15. Model for characterization of a vortex pair formed by shock passage over a light-gas inhomogeneity

    SciTech Connect

    Yang, J.; Kubota, T.; Zukoski, E.E.

    1994-01-01

    This work investigates the two-dimensional flow of a shock wave over a circular light-gas inhomogeneity in a channel with finite width. The pressure gradient from the shock wave interacts with the density gradient at the edge of the inhomogeneity to deposit vorticity around the perimeter, and the structure rolls up into a pair of counter-rotating vortices. The aim of this study is to develop an understanding of the scaling laws for the flow field produced by this interaction at times long after the passage of the shock across the inhomogeneity. Numerical simulations are performed for various initial conditions and the results are used to guide the development of relatively simple algebraic models that characterize the dynamics of the vortex pair, and that allow extrapolation of the numerical results to conditions more nearly of interest in practical situations. The models are not derived directly from the equations of motion but depend on these equations and on intuition guided by the numerical results. Agreement between simulations and models is generally good except for a vortex-spacing model which is less satisfactory. A practical application of this shock-induced vortical flow is rapid and efficient mixing of fuel and oxidizer in a SCRAMJET combustion chamber. One possible injector design uses the interaction of an oblique shock wave with a jet of light fuel to generate vorticity which stirs and mixes the two fluids and lifts the burning jet away from the combustor wall. Marble proposed an analogy between this three-dimensional steady flow and the two-dimensional unsteady problem of the present investigation. Comparison is made between closely corresponding three-dimensional steady and two-dimensional unsteady flows, and a mathematical description of Marble`s analogy is proposed. 17 refs.

  16. Shocked gas in IRAS F17207-0014: ISM collisions and outflows

    NASA Astrophysics Data System (ADS)

    Medling, Anne M.; U, Vivian; Rich, Jeffrey A.; Kewley, Lisa J.; Armus, Lee; Dopita, Michael A.; Max, Claire E.; Sanders, David; Sutherland, Ralph

    2015-04-01

    We combine optical and near-infrared adaptive optics-assisted integral field observations of the merging ultraluminous infrared galaxies IRAS F17207-0014 from the Wide-Field Spectrograph and Keck/OH-Suppressing Infra-Red Imaging Spectrograph (OSIRIS). The optical emission line ratios [N II]/Hα, [S II]/Hα, and [O I]/Hα reveal a mixing sequence of shocks present throughout the galaxy, with the strongest contributions coming from large radii (up to 100 per cent at ˜5 kpc in some directions), suggesting galactic-scale winds. The near-infrared observations, which have approximately 30 times higher spatial resolution, show that two sorts of shocks are present in the vicinity of the merging nuclei: low-level shocks distributed throughout our field-of-view evidenced by an H2/Brγ line ratio of ˜0.6-4, and strong collimated shocks with a high H2/Brγ line ratio of ˜4-8, extending south from the two nuclear discs approximately 400 pc (˜0.5 arcsec). Our data suggest that the diffuse shocks are caused by the collision of the interstellar media associated with the two progenitor galaxies and the strong shocks trace the base of a collimated outflow coming from the nucleus of one of the two discs.

  17. Stockpile Stewardship: Los Alamos

    SciTech Connect

    McMillan, Charlie; Morgan, Nathanial; Goorley, Tom; Merrill, Frank; Funk, Dave; Korzekwa, Deniece; Laintz, Ken

    2012-01-26

    "Heritage of Science" is a short video that highlights the Stockpile Stewardship program at Los Alamos National Laboratory. Stockpile Stewardship was conceived in the early 1990s as a national science-based program that could assure the safety, security, and effectiveness of the U.S. nuclear deterrent without the need for full-scale underground nuclear testing. This video was produced by Los Alamos National Laboratory for screening at the Lab's Bradbury Science Museum in Los Alamos, NM and is narrated by science correspondent Miles O'Brien.

  18. Stockpile Stewardship: Los Alamos

    ScienceCinema

    McMillan, Charlie; Morgan, Nathanial; Goorley, Tom; Merrill, Frank; Funk, Dave; Korzekwa, Deniece; Laintz, Ken

    2016-07-12

    "Heritage of Science" is a short video that highlights the Stockpile Stewardship program at Los Alamos National Laboratory. Stockpile Stewardship was conceived in the early 1990s as a national science-based program that could assure the safety, security, and effectiveness of the U.S. nuclear deterrent without the need for full-scale underground nuclear testing. This video was produced by Los Alamos National Laboratory for screening at the Lab's Bradbury Science Museum in Los Alamos, NM and is narrated by science correspondent Miles O'Brien.

  19. Shock wave induced evaporation of water droplets in a gas-droplet mixture

    NASA Astrophysics Data System (ADS)

    Goossens, H. W. J.; Cleijne, J. W.; Smolders, H. J.; van Dongen, M. E. H.

    1988-01-01

    A model is presented for the droplet evaporation process induced by a shock wave propagating in a fog. The model is based on the existence of a quasi-steady wet bulb state of the droplets during evaporation. It is shown that for moderate shock strength, Ma = less than 2, and droplet radii in the range of 1-5 microns, the major part of the evaporation process is governed by a balance between heat conduction and vapor diffusion. The formation of a fog by means of an unsteady adiabatic expansion of humid nitrogen is described. Experimental results of shock induced evaporation are shown for shock Mach numbers from 1.2 to 2.1, droplet mass fraction of 0.005, and initial droplet radii of 1-1.4 microns. The expected linear relation between droplet radius squared and time during evaporation is observed. Characteristic evaporation times appear to be strongly dependent on shock strength. A variation of about two decades, predicted by theory, was experimentally observed for the Mach number range studied.

  20. Experimental and numerical investigation of shock wave propagation through complex geometry, gas continuous, two-phase media

    SciTech Connect

    Liu, J. Chien-Chih

    1993-10-01

    The work presented here investigates the phenomenon of shock wave propagation in gas continuous, two-phase media. The motivation for this work stems from the need to understand blast venting consequences in the HYLIFE inertial confinement fusion (ICF) reactor. The HYLIFE concept utilizes lasers or heavy ion beams to rapidly heat and compress D-T targets injected into the center of a reactor chamber. A segmented blanket of failing molten lithium or Li{sub 2}BeF{sub 4} (Flibe) jets encircles the reactors central cavity, shielding the reactor structure from radiation damage, absorbing the fusion energy, and breeding more tritium fuel.

  1. Numerical study of shock wave interaction in steady flows of a viscous heat-conducting gas with a low ratio of specific heats

    NASA Astrophysics Data System (ADS)

    Shoev, G. V.; Ivanov, M. S.

    2016-05-01

    Specific features of shock wave interaction in a viscous heat-conducting gas with a low ratio of specific heats are numerically studied. The case of the Mach reflection of shock waves with a negative angle of the reflected wave with respect to the free-stream velocity vector is considered, and the influence of viscosity on the flow structure is analyzed. Various issues of nonuniqueness of the shock wave configuration for different Reynolds numbers are discussed. Depending on the initial conditions and Reynolds numbers, two different shock wave configurations may exist: regular configuration interacting with an expansion fan and Mach configuration. In the dual solution domain, a possibility of the transition from regular to the Mach reflection of shock waves is considered.

  2. Similarity solution for the flow behind a shock wave in a non-ideal gas with heat conduction and radiation heat-flux in magnetogasdynamics

    NASA Astrophysics Data System (ADS)

    Nath, G.; Vishwakarma, J. P.

    2014-05-01

    The propagation of a spherical (or cylindrical) shock wave in a non-ideal gas with heat conduction and radiation heat-flux, in the presence of a spacially decreasing azimuthal magnetic field, driven out by a moving piston is investigated. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature and density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. The shock wave moves with variable velocity and the total energy of the wave is non-constant. Similarity solutions are obtained for the flow-field behind the shock and the effects of variation of the heat transfer parameters, the parameter of the non-idealness of the gas, both, decreases the compressibility of the gas and hence there is a decrease in the shock strength. Further, it is investigated that with an increase in the parameters of radiative and conductive heat transfer the tendency of formation of maxima in the distributions of heat flux, density and isothermal speed of sound decreases. The pressure and density vanish at the inner surface (piston) and hence a vacuum is form at the center of symmetry. The shock waves in conducting non-ideal gas with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, nuclear explosion, chemical detonation, rupture of a pressurized vessels, in the analysis of data from exploding wire experiments, and cylindrically symmetric hypersonic flow problems associated with meteors or reentry vehicles, etc. The findings of the present works provided a clear picture of whether and how the non-idealness parameter, conductive and radiative heat transfer parameters and the magnetic field affect the flow behind the shock

  3. Evidence for shock-heated gas in the Hopkins Ultraviolet Telescope spectrum of NGC 1068

    NASA Technical Reports Server (NTRS)

    Kriss, Gerard A.; Davidsen, Arthur F.; Blair, William P.; Ferguson, Henry C.; Long, Knox S.

    1992-01-01

    The paper presents FUV spectra of the NGC 1068 Seyfert 2 galaxy, obtained with the Hopkins Ultraviolet Telescope (HUT) during the flight of Astro-1 aboard the Space Shuttle Columbia in December 1990, revealing moderately strong C III 977-A and N III 991-A emission lines, which have never been seen before in spectra of AGNs. It is noted that the emission-line spectrum of NGC 1068 qualitatively resemble the HUT spectrum of a radiative shock in the Cygnus Loop supernova remnant (Blair et al., 1991), suggesting that shock heating may contribute significantly to the line emission.

  4. Application of program LAURA to perfect gas shock tube flows: A parametric study

    NASA Technical Reports Server (NTRS)

    Mitterer, K. F.; Mitcheltree, R. A.; Gnoffo, P. A.

    1992-01-01

    The Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) was originally developed to solve steady-flow problems. The desire to validate the algorithm with shock tube experimental data motivated the development of a time-accurate version of the LAURA code. The current work presents a test of the Algorithm. Computational results are compared with the exact solution for a simple shock tube case. The parameters examined are Courant number, relaxation sweeps, grid spacing, and the inviscid relaxation factor. The results of the study indicate that LAURA is capable of producing accurate solutions when appropriate values are used for each parameter.

  5. Analysis of a two-dimensional type 6 shock-interference pattern using a perfect-gas code and a real-gas code

    NASA Technical Reports Server (NTRS)

    Bertin, J. J.; Graumann, B. W.

    1973-01-01

    Numerical codes were developed to calculate the two dimensional flow field which results when supersonic flow encounters double wedge configurations whose angles are such that a type 4 pattern occurs. The flow field model included the shock interaction phenomena for a delta wing orbiter. Two numerical codes were developed, one which used the perfect gas relations and a second which incorporated a Mollier table to define equilibrium air properties. The two codes were used to generate theoretical surface pressure and heat transfer distributions for velocities from 3,821 feet per second to an entry condition of 25,000 feet per second.

  6. The heating of gas in a galaxy cluster by X-ray cavities and large-scale shock fronts.

    PubMed

    McNamara, B R; Nulsen, P E J; Wise, M W; Rafferty, D A; Carilli, C; Sarazin, C L; Blanton, E L

    2005-01-01

    Most of the baryons in galaxy clusters reside between the galaxies in a hot, tenuous gas. The densest gas in their centres should cool and accrete onto giant central galaxies at rates of 10-1,000 solar masses per year. No viable repository for this gas, such as clouds or new stars, has been found. New X-ray observations, however, have revealed far less cooling below X-ray temperatures than expected, altering the previously accepted picture of cooling flows. As a result, most of the gas must be heated to and maintained at temperatures above approximately 2 keV (ref. 3). The most promising heating mechanism is powerful radio jets emanating from supermassive black holes in the central galaxies of clusters. Here we report the discovery of giant cavities and shock fronts in a distant (z = 0.22) cluster caused by an interaction between a radio source and the hot gas surrounding it. The energy involved is approximately 6 x 10(61) erg, the most powerful radio outburst known. This is enough energy to quench a cooling flow for several Gyr, and to provide approximately 1/3 keV per particle of heat to the surrounding cluster.

  7. Passage of a shock wave through inhomogeneous media and its impact on gas-bubble deformation.

    PubMed

    Nowakowski, A F; Ballil, A; Nicolleau, F C G A

    2015-08-01

    The paper investigates shock-induced vortical flows within inhomogeneous media of nonuniform thermodynamic properties. Numerical simulations are performed using a Eulerian type mathematical model for compressible multicomponent flow problems. The model, which accounts for pressure nonequilibrium and applies different equations of state for individual flow components, shows excellent capabilities for the resolution of interfaces separating compressible fluids as well as for capturing the baroclinic source of vorticity generation. The developed finite volume Godunov type computational approach is equipped with an approximate Riemann solver for calculating fluxes and handles numerically diffused zones at flow component interfaces. The computations are performed for various initial conditions and are compared with available experimental data. The initial conditions promoting a shock-bubble interaction process include weak to high planar shock waves with a Mach number ranging from 1.2 to 3 and isolated cylindrical bubble inhomogeneities of helium, argon, nitrogen, krypton, and sulphur hexafluoride. The numerical results reveal the characteristic features of the evolving flow topology. The impulsively generated flow perturbations are dominated by the reflection and refraction of the shock, the compression, and acceleration as well as the vorticity generation within the medium. The study is further extended to investigate the influence of the ratio of the heat capacities on the interface deformation. PMID:26382524

  8. Three dimensional simulations of Richtmyer-Meshkov instabilities in gas-curtain shock-tube experiments

    SciTech Connect

    Gowardhan, Akshay A; Grinstein, Fernando F

    2009-01-01

    It is not feasible to compute high Reynolds-number (Re) turbulent flows by directly resolving all scales of motion and material interfaces; instead, macroscale portions of the unsteady turbulent motion are computed while the rest of the flow physics including molecular diffusion and other micro scale physics (e.g., combustion) remains unresolved. In large eddy simulation (LES), the large energy containing structures are resolved whereas the smaller, presumably more isotropic, structures are filtered out and their unresolved subgrid scale (SGS) effects are modeled. The construction of SGS models for LES is pragmatic and based primarily on empirical information. Adding to the physics based difficulties in developing and validating SGS models, truncation terms due to discretization are comparable to SGS models in typical LES strategies, and LES resolution requirements become prohibitively expensive for practical flows and regimes. Implicit LES (ILES) - and monotone integrated LES (MILES) introduced earlier, effectively address the seemingly insurmountable issues posed to LES by underresolution, by relying on the use of SGS modeling and filtering provided implicitly by physics capturing numerics. Extensive work has demonstrated that predictive unresolved simulations of turbulent velocity fields are possible using any of the class of nonoscillatory finite-volume (NFV) numerical algorithms. Popular NFV methods such as flux-corrected transport (FCT), the piecewise parabolic method (PPM), total variation diminishing (TVD), and hybrid algorithms are being used for ILES. In many applications of interest, turbulence is generated by shock waves via Richtmyer-Meshkov instabilities (RMI). The instability results in vorticity being introduced at material interfaces by the impulsive loading of the shock wave. A critical feature of this impulsive driving is that the turbulence decays as dissipation removes kinetic energy from the system. RMI add the complexity of shock waves and

  9. RADIO SYNCHROTRON EMISSION FROM A BOW SHOCK AROUND THE GAS CLOUD G2 HEADING TOWARD THE GALACTIC CENTER

    SciTech Connect

    Narayan, Ramesh; Sironi, Lorenzo; Oezel, Feryal

    2012-10-01

    A dense ionized cloud of gas has been recently discovered to be moving directly toward the supermassive black hole, Sgr A*, at the Galactic center. In 2013 June, at the pericenter of its highly eccentric orbit, the cloud will be approximately 3100 Schwarzschild radii from the black hole and will move supersonically through the ambient hot gas with a velocity of v{sub p} Almost-Equal-To 5400 km s{sup -1}. A bow shock is likely to form in front of the cloud and could accelerate electrons to relativistic energies. We estimate via particle-in-cell simulations the energy distribution of the accelerated electrons and show that the non-thermal synchrotron emission from these electrons might exceed the quiescent radio emission from Sgr A* by a factor of several. The enhanced radio emission should be detectable at GHz and higher frequencies around the time of pericentric passage and in the following months. The bow shock emission is expected to be displaced from the quiescent radio emission of Sgr A* by {approx}33 mas. Interferometric observations could resolve potential changes in the radio image of Sgr A* at wavelengths {approx}< 6 cm.

  10. Magnetogasdynamics shock waves in a rotational axisymmetric non-ideal gas with increasing energy and conductive and radiative heat-fluxes

    NASA Astrophysics Data System (ADS)

    Nath, Gorakh

    2016-07-01

    Self-similar solutions are obtained for one-dimensional adiabatic flow behind a magnetogasdynamics cylindrical shock wave propagating in a rotational axisymmetric non ideal gas with increasing energy and conductive and radiative heat fluxes in presence of an azimuthal magnetic field. The fluid velocities and the azimuthal magnetic field in the ambient medium are assume to be varying and obeying power laws. In order to find the similarity solutions the angular velocity of the ambient medium is taken to be decreasing as the distance from the axis increases. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be the diffusion type for an optically thick grey gas model. The thermal conductivity and the absorption coefficient are assumed to vary with temperature and density. The effects of the presence of radiation and conduction, the non-idealness of the gas and the magnetic field on the shock propagation and the flow behind the shock are investigated.

  11. Los Alamos offers Fellowships

    NASA Astrophysics Data System (ADS)

    Los Alamos National Laboratory in New Mexico is calling for applications for postdoctoral appointments and research fellowships. The positions are available in geoscience as well as other scientific disciplines.The laboratory, which is operated by the University of California for the Department of Energy, awards J. Robert Oppenheimer Research Fellowships to scientists that either have or will soon complete doctoral degrees. The appointments are for two years, are renewable for a third year, and carry a stipend of $51,865 per year. Potential applicants should send a resume or employment application and a statement of research goals to Carol M. Rich, Div. 89, Human Resources Development Division, MS P290, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 by mid-November.

  12. Ratios of molecular hydrogen line intensities in shocked gas - Evidence for cooling zones

    NASA Technical Reports Server (NTRS)

    Brand, P. W. J. L.; Moorhouse, A.; Bird, M.; Burton, M. G.; Geballe, T. R.

    1988-01-01

    Column densities of molecular hydrogen have been calculated from 19 infrared vibration-rotation and pure rotational line intensities measured at peak 1 of the Orion molecular outflow. The run of column density with energy level is similar to a simple coolng zone model of the line-emitting region, but is not well fitted by predictions of C-shock models current in the literature.

  13. Advancement of Shock-wave Induced Spraying Process through the Study of Gas and Particle Flow Fields

    NASA Astrophysics Data System (ADS)

    Karimi Esfahani, Mohammad

    This research advances the knowledge of the working principles of the Shock-wave Induced Spraying Process (SISP), a thermal spray material deposition technique. Pulses created by a fast acting valve pass through a heated line increasing energy content and interacting with metered batches of heated or non-heated powder introduced into the line. The powder is accelerated to high velocities before bonding to the substrate upon impact. Advantages over other cold spray processes include cost savings and a more effective transfer of thermal energy to the powder. The shock-wave occurring near the substrate in other cold spray processes is avoided. The SISP flow field is resolved by using a computational model. The two-dimensional model accounts for the valve, gas heater, a tapered nozzle at the tip of the device, and preheating of the powder. It is implemented with a commercial computational fluid dynamics code. Comparisons are made with one-dimensional predictions, and measurements of pressure and temperature. Particle flow predictions are validated using particle velocity and adhesion measurements. A flow region of both high temperature and velocity gas, favorable to material deposition, forms which is not present in comparable steady-state cold spray processes. Increasing gas pressure increases the gas speed, while increasing temperature increases speed and temperature of this region. Using helium results in greater energy levels but for shorter periods of time. This indicates the need for a powder feeder which places particles in the flow at correct instants and durations of time. The effects of particle flow parameters on system performance are examined. It is found that the device must be operated at very high main heater and powder heater temperatures: 900 °C and 700 °C respectively to achieve a coating with stainless steel using nitrogen as the driving gas. It is also shown that a heater length range of 0.9 m to 1.4 m results in the greatest likelihood of

  14. HERSCHEL* FAR-INFRARED SPECTROSCOPY OF THE GALACTIC CENTER. HOT MOLECULAR GAS: SHOCKS VERSUS RADIATION NEAR Sgr A

    SciTech Connect

    Goicoechea, Javier R.; Etxaluze, M.; Cernicharo, J.; Bell, T. A.; Gerin, M.; De Luca, M.; Encrenaz, P.; Neufeld, D. A.; Indriolo, N.; Contursi, A.; Lis, D. C.; Polehampton, E. T.; Sonnentrucker, P.

    2013-05-20

    We present a {approx}52-671 {mu}m spectral scan toward Sgr A* taken with the PACS and SPIRE spectrometers on board Herschel. The achieved angular resolution allows us to separate, for the first time at far-IR wavelengths, the emission toward the central cavity (gas in the inner central parsec of the galaxy) from that of the surrounding circumnuclear disk. The spectrum toward Sgr A* is dominated by strong [O III], [O I], [C II], [N III], [N II], and [C I] fine-structure lines (in decreasing order of luminosity) arising in gas irradiated by UV photons from the central stellar cluster. In addition, rotationally excited lines of {sup 12}CO (from J = 4-3 to 24-23), {sup 13}CO, H{sub 2}O, OH, H{sub 3}O{sup +}, HCO{sup +}, and HCN, as well as ground-state absorption lines of OH{sup +}, H{sub 2}O{sup +}, H{sub 3}O{sup +}, CH{sup +}, H{sub 2}O, OH, HF, CH, and NH are detected. The excitation of the {sup 12}CO ladder is consistent with a hot isothermal component at T{sub k} {approx_equal} 10{sup 3.1} K and n(H{sub 2}) {approx}< 10{sup 4} cm{sup -3}. It is also consistent with a distribution of temperature components at higher density with most CO at T{sub k} {approx}< 300 K. The detected molecular features suggest that, at present, neither very enhanced X-ray nor cosmic-ray fluxes play a dominant role in the heating of the hot molecular gas. The hot CO component (either the bulk of the CO column or just a small fraction depending on the above scenario) results from a combination of UV- and shock-driven heating. If irradiated dense clumps/clouds do not exist, shocks likely dominate the heating of the hot molecular gas. This is consistent with the high-velocity gas detected toward Sgr A*.

  15. The Los Alamos primer

    SciTech Connect

    Serber, R.

    1992-01-01

    This book contains the 1943 lecture notes of Robert Serber. Serber was a protege of J. Robert Oppenheimer and member of the team that built the first atomic bomb - reveal what the Los Alamos scientists knew, and did not know, about the terrifying weapon they were building.

  16. The Chandra Delta Ori Large Project: Occultation Measurements of the Shocked Gas tn the Nearest Eclipsing O-Star Binary

    NASA Technical Reports Server (NTRS)

    Corcoran, Michael F.; Nichols, Joy; Naze, Yael; Rauw, Gregor; Pollock, Andrew; Moffat, Anthony; Richardson, Noel; Evans, Nancy; Hamaguchi, Kenji; Oskinova, Lida; Hamann, W. -R.; Gull, Ted; Ignace, Rico; Hole, Tabetha; Iping, Rosina; Walborn, Nolan; Hoffman, Jennifer; Lomax, Jamie; Waldron, Wayne; Owocki, Stan; Maiz-Apellaniz, Jesus; Leutenegger, Maurice; Hole, Tabetha; Gayley, Ken; Russell, Chris

    2013-01-01

    Delta Ori is the nearest massive, single-lined eclipsing binary (O9.5 II + B0.5III). As such it serves as a fundamental calibrator of the mass-radius-luminosity relation in the upper HR diagram. It is also the only eclipsing O-type binary system which is bright enough to be observable with the CHANDRA gratings in a reasonable exposure. Studies of resolved X-ray line complexes provide tracers of wind mass loss rate and clumpiness; occultation by the X-ray dark companion of the line emitting region can provide direct spatial information on the location of the X-ray emitting gas produced by shocks embedded in the wind of the primary star. We obtained phase-resolved spectra with Chandra in order to determine the level of phase-dependent vs. secular variability in the shocked wind. Along with the Chandra observations we obtained simultaneous photometry from space with the Canadian MOST satellite to help understand the relation between X-ray and photospheric variability.

  17. Near-vertical supersonic and shock-free gas/magma flow at ionian volcanoes: Application to Pillan

    NASA Astrophysics Data System (ADS)

    Cataldo, Enzo; Davies, Ashley Gerard; Wilson, Lionel

    2013-09-01

    In 1997, the Pillan volcano on Io was home to a fierce volcanic eruption that emplaced extensive lava flows and a circular plume deposit. The gas/magma flow issuing from the unresolved vent region appeared to form an almost vertical jet. We consider steady eruptions of gas and magma, and take the vent to be either a fissure or a point source. In the fissure scenario, the upper-conduit flow must reach Mach 1 in the 25-75 m depth range to produce the vent velocities of 550-600 m/s that are required to explain the observed plume heights. Conduit wall deflections in the range 20-30° from vertical (values referring to the upper meter of the conduit) and ∼26-30% by mass of incorporated crustal SO2 are also needed. In the point-source scenario, sonic flow conditions and similar velocities are achieved in the depth range 350-500 m for similar conduit wall deflections and gas mass proportions in the erupting mixture. Probably, the source of the 140-km-high plume imaged in 1997 was either a ∼6-11 m-wide fissure, active for ∼14-40 km along strike, or a circular vent ∼125-216 m in diameter, the former scenario being preferred. Finally, a shock-free conduit flow is more likely to sustain a tall lava fountain in a near-vacuum.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    SciTech Connect

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

    2015-12-15

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

  20. Numerical analysis of gas and micro-particle interactions in a hand-held shock-tube device.

    PubMed

    Liu, Y; Kendall, M A F

    2006-12-01

    A unique hand-held gene gun is employed for ballistically delivering biomolecules to key cells in the skin and mucosa in the treatment of the major diseases. One of these types of devices, called the Contoured Shock Tube (CST), delivers powdered micro-particles to the skin with a narrow and highly controllable velocity distribution and a nominally uniform spatial distribution. In this paper, we apply a numerical approach to gain new insights in to the behavior of the CST prototype device. The drag correlations proposed by Henderson (1976), Igra and Takayama (1993) and Kurian and Das (1997) were applied to predict the micro-particle transport in a numerically simulated gas flow. Simulated pressure histories agree well with the corresponding static and Pitot pressure measurements, validating the CFD approach. The calculated velocity distributions show a good agreement, with the best prediction from Igra & Takayama correlation (maximum discrepancy of 5%). Key features of the gas dynamics and gas-particle interaction are discussed. Statistic analyses show a tight free-jet particle velocity distribution is achieved (570 +/- 14.7 m/s) for polystyrene particles (39 +/- 1 microm), representative of a drug payload. PMID:16917664

  1. Application of TVD schemes for the Euler equations of gas dynamics. [method of Total Variation Diminishing for shock wave computation

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Warming, R. F.; Harten, A.

    1985-01-01

    Highly accurate and yet stable shock-capturing finite difference schemes have been designed for the computation of the Euler equations of gas dynamics. Four different principles for the construction of high resolution total variation diminishing (TVD) schemes are available, including hybrid schemes, a second-order extension of Godunov's scheme by van Leer (1979), the modified flux approach of Harten (1983, 1984), and the numerical fluctuation approach of Roe (1985). The present paper has the objective to review the class of second-order TVD schemes via the modified flux approach. Attention is given to first-order TVD schemes, a second-order accurate explicit TVD scheme, the global order of accuracy of the second-order TVD scheme, extensions to systems and two-dimensional conservation laws, numerical experiments with a second-order explicit TVD scheme, implicit TVD schemes, and second-order implicit TVD schemes.

  2. Resistance and resilience of removal efficiency and bacterial community structure of gas biofilters exposed to repeated shock loads.

    PubMed

    Cabrol, Léa; Malhautier, Luc; Poly, Franck; Roux, Xavier Le; Lepeuple, Anne-Sophie; Fanlo, Jean-Louis

    2012-11-01

    Since full-scale biofilters are often operated under fluctuating conditions, it is critical to understand their response to transient states. Four pilot-scale biofilters treating a composting gas mixture and undergoing repeated substrate pulses of increasing intensity were studied. A systematic approach was proposed to quantify the resistance and resilience capacity of their removal efficiency, which enabled to distinguish between recalcitrant (ammonia, DMDS, ketones) and easily degradable (esters and aldehyde) compounds. The threshold of disturbing shock intensity and the influence of disturbance history depended on the contaminant considered. The spatial and temporal distribution of the bacterial community structure in response to the perturbation regime was analysed by Denaturing Gradient Gel Electrophoresis (DGGE). Even if the substrate-pulses acted as a driving force for some community characteristics (community stratification), the structure-function relationships were trickier to evidence: the distributions of resistance and composition were only partially coupled, with contradictory results depending on the contaminant considered.

  3. Ammonia excitation imaging of shocked gas towards the W28 gamma-ray source HESS J1801-233

    NASA Astrophysics Data System (ADS)

    Maxted, Nigel I.; de Wilt, Phoebe; Rowell, Gavin P.; Nicholas, Brent P.; Burton, Michael. G.; Walsh, Andrew; Fukui, Yasuo; Kawamura, Akiko

    2016-10-01

    We present 12 mm Mopra observations of the dense (>103 cm-3) molecular gas towards the north-east of the W28 supernova remnant (SNR). This cloud is spatially well matched to the TeV gamma-ray source HESS J1801-233 and is known to be an SNR-molecular cloud interaction region. Shock-disruption is evident from broad NH3 (1,1) spectral linewidths in regions towards the W28 SNR, while strong detections of spatially extended NH3 (3,3), NH3(4,4) and NH3(6,6) inversion emission towards the cloud strengthen the case for the existence of high temperatures within the cloud. Velocity dispersion measurements and NH3(n,n)/(1,1) ratio maps, where n = 2, 3, 4 and 6, indicate that the source of disruption is from the side of the cloud nearest to the W28 SNR, suggesting that it is the source of cloud-disruption. Towards part of the cloud, the ratio of ortho to para-NH3 is observed to exceed 2, suggesting gas-phase NH3 enrichment due to NH3 liberation from dust-grain mantles. The measured NH3 abundance with respect to H2 is ˜(1.2 ± 0.5) × 10-9, which is not high, as might be expected for a hot, dense molecular cloud enriched by sublimated grain-surface molecules. The results are suggestive of NH3 sublimation and destruction in this molecular cloud, which is likely to be interacting with the W28 SNR shock.

  4. Neptune inbound bow shock

    NASA Technical Reports Server (NTRS)

    Szabo, Adam; Lepping, Ronald P.

    1995-01-01

    Voyager 2 crossed the inbound or upstream Neptunian bow shock at 1430 spacecraft event time on August 24 in 1989 (Belcher et al., 1989). The plasma and magnetic field measurements allow us to study the solar wind interaction with the outermost gas giant. To fully utilize all of the spacecraft observations, an improved nonlinear least squares, 'Rankine-Hugoniot' magnetohydrodynamic shock-fitting technique has been developed (Szabo, 1994). This technique is applied to the Neptunian data set. We find that the upstream bow shock normal points nearly exactly toward the Sun consistent with any reasonable large-scale model of the bow shock for a near subsolar crossing. The shock was moving outward with a speed of 14 +/- 12 km/s. The shock can be characterized as a low beta, high Mach number, strong quasi-perpendicular shock. Finally, the shock microstructure features are resolved and found to scale well with theoretical expectations.

  5. Bronchoscopic administration of bovine natural surfactant in ARDS and septic shock: impact on gas exchange and haemodynamics.

    PubMed

    Walmrath, D; Grimminger, F; Pappert, D; Knothe, C; Obertacke, U; Benzing, A; Günther, A; Schmehl, T; Leuchte, H; Seeger, W

    2002-05-01

    The aim of the present study was to investigate the feasibility and efficacy of bronchoscopic surfactant administration in a noncontrolled multicentre study in five university centres. A total number of 27 patients, suffering from severe acute respiratory distress syndrome (mean+/-SEM lung injury score: 3.15+/-0.06) and septic shock (Acute Physiology and Chronic Health Evaluation (APACHE) II score at study entry 33.2+/-1.3, lactate 4.3+/-0.6 mmol x L(-1)) were studied. The patients were ventilated with a mean tidal volume of 11.0+/-0.5 mL x kg(-1) body weight (bw), either volume or pressure controlled, with 16.3+/-2.8 cmH2O positive end-expiratory pressure, for an average of 3.5+/-0.3 days at study entry. A natural bovine surfactant extract (300 mg x kg(-1) bw Alveofact; mean total volume 378 mL) was delivered in divided doses to each segment of the lungs via flexible bronchoscope within approximately 45 min. No untoward effects on gas exchange, lung mechanics and haemodynamics were noted during the procedure of surfactant administration. Within 12 h the oxygen tension in arterial blood/inspiratory oxygen fraction increased from a mean of 109+/-8 mmHg to 210+/-20 mmHg (p<0.001). In seven patients, in whom gas exchange again deteriorated with further progression of the disease, a second surfactant dose of 200 mg x kg(-1) was administered 18-24 h after the first application, again improving arterial oxygenation. A total of 15 patients survived the 28-day study period (mortality rate 44.4%, compared to a calculated risk of death for the given APACHE II scores of 74.0+/-3.5%), with all causes of death being nonrespiratory. The bronchoscopic application of a high dose of natural surfactant in patients with severe acute respiratory distress syndrome and septic shock is both feasible and safe, resulting in a pronounced improvement in gas exchange.

  6. INVESTIGATION OF DUAL ACTIVE NUCLEI, OUTFLOWS, SHOCK-HEATED GAS, AND YOUNG STAR CLUSTERS IN MARKARIAN 266

    SciTech Connect

    Mazzarella, J. M.; Chan, B. H. P.; Iwasawa, K. E-mail: bchan@ipac.caltech.edu; and others

    2012-11-01

    Results of observations with the Spitzer, Hubble, GALEX, Chandra, and XMM-Newton space telescopes are presented for the luminous infrared galaxy (LIRG) merger Markarian 266. The SW (Seyfert 2) and NE (LINER) nuclei reside in galaxies with Hubble types SBb (pec) and S0/a (pec), respectively. Both companions are more luminous than L* galaxies and they are inferred to each contain a Almost-Equal-To 2.5 Multiplication-Sign 10{sup 8} M{sub Sun} black hole. Although the nuclei have an observed hard X-ray flux ratio of f{sub X} (NE)/f{sub X} (SW) = 6.4, Mrk 266 SW is likely the primary source of a bright Fe K{alpha} line detected from the system, consistent with the reflection-dominated X-ray spectrum of a heavily obscured active galactic nucleus (AGN). Optical knots embedded in an arc with aligned radio continuum radiation, combined with luminous H{sub 2} line emission, provide evidence for a radiative bow shock in an AGN-driven outflow surrounding the NE nucleus. A soft X-ray emission feature modeled as shock-heated plasma with T {approx} 10{sup 7} K is cospatial with radio continuum emission between the galaxies. Mid-infrared diagnostics provide mixed results, but overall suggest a composite system with roughly equal contributions of AGN and starburst radiation powering the bolometric luminosity. Approximately 120 star clusters have been detected, with most having estimated ages less than 50 Myr. Detection of 24 {mu}m emission aligned with soft X-rays, radio continuum, and ionized gas emission extending {approx}34'' (20 kpc) north of the galaxies is interpreted as {approx}2 Multiplication-Sign 10{sup 7} M{sub Sun} of dust entrained in an outflowing superwind. At optical wavelengths this Northern Loop region is resolved into a fragmented morphology indicative of Rayleigh-Taylor instabilities in an expanding shell of ionized gas. Mrk 266 demonstrates that the dust 'blow-out' phase can begin in a LIRG well before the galaxies fully coalesce during a subsequent

  7. Similarity Solutions for the Flow Behind an Exponential Shock in a Rotating Nonideal Gas with Heat Conduction and Radiation Heat Fluxes

    NASA Astrophysics Data System (ADS)

    Singh, K. K.; Nath, B.

    2014-07-01

    A self-similar solution for the propagation of a shock wave driven by a cylindrical piston moving according to exponential temporal law in a nonideal rotating gas with heat conduction and radiation heat fluxes is investigated. The density and angular velocity of the ambient medium are assumed to be constant. Heat conduction is expressed in terms of the Fourier law, and radiation is considered to be of diffusion type for an optically thick gray gas model. The thermal conductivity and absorption coefficient are assumed to vary with temperature and density. Similarity solutions are obtained, and the effects of variations in the heat transfer parameters and gas nonidealness on the flow variables in the region behind the shock are investigated.

  8. Large-eddy and unsteady RANS simulations of a shock-accelerated heavy gas cylinder

    SciTech Connect

    Morgan, B. E.; Greenough, J. A.

    2015-04-08

    Two-dimensional numerical simulations of the Richtmyer–Meshkov unstable “shock-jet” problem are conducted using both large-eddy simulation (LES) and unsteady Reynolds-averaged Navier–Stokes (URANS) approaches in an arbitrary Lagrangian–Eulerian hydrodynamics code. Turbulence statistics are extracted from LES by running an ensemble of simulations with multimode perturbations to the initial conditions. Detailed grid convergence studies are conducted, and LES results are found to agree well with both experiment and high-order simulations conducted by Shankar et al. (Phys Fluids 23, 024102, 2011). URANS results using a k–L approach are found to be highly sensitive to initialization of the turbulence lengthscale L and to the time at which L becomes resolved on the computational mesh. As a result, it is observed that a gradient diffusion closure for turbulent species flux is a poor approximation at early times, and a new closure based on the mass-flux velocity is proposed for low-Reynolds-number mixing.

  9. Large-eddy and unsteady RANS simulations of a shock-accelerated heavy gas cylinder

    NASA Astrophysics Data System (ADS)

    Morgan, B. E.; Greenough, J. A.

    2016-07-01

    Two-dimensional numerical simulations of the Richtmyer-Meshkov unstable "shock-jet" problem are conducted using both large-eddy simulation (LES) and unsteady Reynolds-averaged Navier-Stokes (URANS) approaches in an arbitrary Lagrangian-Eulerian hydrodynamics code. Turbulence statistics are extracted from LES by running an ensemble of simulations with multimode perturbations to the initial conditions. Detailed grid convergence studies are conducted, and LES results are found to agree well with both experiment and high-order simulations conducted by Shankar et al. (Phys Fluids 23, 024102, 2011). URANS results using a k- L approach are found to be highly sensitive to initialization of the turbulence lengthscale L and to the time at which L becomes resolved on the computational mesh. It is observed that a gradient diffusion closure for turbulent species flux is a poor approximation at early times, and a new closure based on the mass-flux velocity is proposed for low-Reynolds-number mixing.

  10. Large-eddy and unsteady RANS simulations of a shock-accelerated heavy gas cylinder

    DOE PAGES

    Morgan, B. E.; Greenough, J. A.

    2015-04-08

    Two-dimensional numerical simulations of the Richtmyer–Meshkov unstable “shock-jet” problem are conducted using both large-eddy simulation (LES) and unsteady Reynolds-averaged Navier–Stokes (URANS) approaches in an arbitrary Lagrangian–Eulerian hydrodynamics code. Turbulence statistics are extracted from LES by running an ensemble of simulations with multimode perturbations to the initial conditions. Detailed grid convergence studies are conducted, and LES results are found to agree well with both experiment and high-order simulations conducted by Shankar et al. (Phys Fluids 23, 024102, 2011). URANS results using a k–L approach are found to be highly sensitive to initialization of the turbulence lengthscale L and to the timemore » at which L becomes resolved on the computational mesh. As a result, it is observed that a gradient diffusion closure for turbulent species flux is a poor approximation at early times, and a new closure based on the mass-flux velocity is proposed for low-Reynolds-number mixing.« less

  11. Statistical comparison between experiments and numerical simulations of shock-accelerated gas cylinders

    SciTech Connect

    Rider, William; Kamm, J. R.; Zoldi, C. A.; Tomkins, C. D.

    2002-01-01

    We present detailed spatial analysis comparing experimental data and numerical simulation results for Richtmyer-Meshkov instability experiments of Prestridge et al. and Tomkins et al. These experiments consist, respectively, of one and two diffuse cylinders of sulphur hexafluoride (SF{sub 6}) impulsively accelerated by a Mach 1.2 shockwave in air. The subsequent fluid evolution and mixing is driven by the deposition of baroclinic vorticity at the interface between the two fluids. Numerical simulations of these experiments are performed with three different versions of high resolution finite volume Godunov methods, including a new weighted adaptive Runge-Kutta (WARK) scheme. We quantify the nature of the mixing using using integral measures as well as fractal analysis and continuous wavelet transforms. Our investigation of the gas cylinder configurations follows the path of our earlier studies of the geometrically and dynamically more complex gas 'curtain' experiment. In those studies, we found significant discrepancies in the details of the experimentally measured mixing and the details of the numerical simulations. Here we evaluate the effects of these hydrodynamic integration techniques on the diffuse gas cylinder simulations, which we quantitatively compare with experimental data.

  12. XMM-Newton observations of RR Telescopii: evidence for wind signatures and shocked gas emission

    NASA Astrophysics Data System (ADS)

    González-Riestra, R.; Selvelli, P.; Cassatella, A.

    2013-08-01

    RR Telescopii is the prototype of the symbiotic novae class. Since its outburst in 1944, it has been slowly fading, and its emission-line spectrum has evolved significantly. In this paper we discuss XMM-Newton observations of RR Tel taken in April 2009. These are the first X-ray high-resolution spectra of this system, and they provide important information about the physical conditions of the emitting gas. We have estimated the temperature and the luminosity of the hot star to be 154 kK and 5000 L⊙, respectively, from the comparison of model atmospheres with the X-ray spectra. Normalisation of the models with the far ultraviolet flux leads to similar values. Both the shape of the low-resolution X-ray spectrum and the spectral diagnostics that make use of the emission lines present in the RGS spectrum indicate the existence of collisionally ionised gas. At least two components are present, with temperatures of ≈0.6 and 1.7 MK. The existence of a wind from the hot star is unequivocally confirmed by HST-STIS observations taken in 2000, which showed displaced absorption components for the N V 1240 Å and C IV 1550 Å doublets. These components have terminal velocities of the order of 400 km s-1, which is consistent with the temperature of the gas detected in X-rays.

  13. Diagnostic system to measure spatial and temporal profiles of shock front using compact two-stage light-gas gun and line reflection method.

    PubMed

    Yokoo, Manabu; Kawai, Nobuaki; Hironaka, Yoichiro; Nakamura, Kazutaka G; Kondo, Ken-Ichi

    2007-04-01

    A diagnostic system has been developed to obtain spatial and temporal profiles of shock front. A two-stage light-gas gun is used to accelerate impactors in velocity range with 4-9 km/s. The system consists of the Faraday-type electromagnetic sensors to measure impactor velocity, optical system with high-speed streak camera to measure shock-wave velocities, and the delay trigger system with self-adjustable pre-event pulse generator. We describe the specifications and performance of this system and data-analysis technique on the tilt and distortion of the shock front. Finally, we obtained the Hugoniot data of copper for system demonstration.

  14. State-to-state vibrational kinetics of H2 and H_2^+ in a post-shock cooling gas with primordial composition

    NASA Astrophysics Data System (ADS)

    Coppola, C. M.; Mizzi, G.; Bruno, D.; Esposito, F.; Galli, D.; Palla, F.; Longo, S.

    2016-04-01

    The radiative cooling of shocked gas with primordial chemical composition is an important process relevant to the formation of the first stars and structures, as well as taking place also in high-velocity cloud collisions and supernovae explosions. Among the different processes that need to be considered, the formation kinetics and cooling of molecular hydrogen are of prime interest, since they provide the only way to lower the gas temperature to values well below ˜104 K. In previous works, the internal energy level structure of H2 and its cation has been treated in the approximation of ro-vibrational ground state at low densities, or trying to describe the dynamics using some arbitrary v > 0 H2 level that is considered representative of the excited vibrational manifold. In this study, we compute the vibrationally resolved kinetics for the time-dependent chemical and thermal evolution of the post-shock gas in a medium of primordial composition. The calculated non-equilibrium distributions are used to evaluate effects on the cooling function of the gas and on the cooling time. Finally, we discuss the dependence of the results to different initial values of the shock velocity and redshift.

  15. Molecular gas dynamics applied to phase change processes at a vapor-liquid interface: shock-tube experiment and MGD computation for methanol

    NASA Astrophysics Data System (ADS)

    Fujikawa, S.; Yano, T.; Kobayashi, K.; Iwanami, K.; Ichijo, M.

    This paper deals with a molecular gas-dynamics method applied to the accurate determination of the condensation coefficient of methanol vapor. The method consisted of an experiment using a shock tube and computations using a molecular gas-dynamics equation. The experiments were performed in such situations where the shift from a vapor-liquid equilibrium state to a nonequilibrium one is realized by a shock wave in a scale of molecular mean free time of vapor molecules. The temporal evolution in thickness of a liquid film formed on the shock-tube endwall behind a reflected shock wave is measured by an optical interferometer. By comparing the measured liquid-film thickness with numerical solutions for a polyatomic version of the Gaussian-BGK model of the Boltzmann equation, the condensation coefficient of methanol vapor is accurately determined in vapor-liquid nonequilibrium states. As a result, it is clear that the condensation coefficient is just unity very near to an equilibrium state, but is smaller far from the equilibrium state.

  16. Effect of a gas on the ejection of particles from the free surface of a sample subjected to a shock wave with various intensities

    NASA Astrophysics Data System (ADS)

    Ogorodnikov, V. A.; Mikhailov, A. L.; Sasik, V. S.; Erunov, S. V.; Syrunin, M. A.; Fedorov, A. V.; Nevmerzhitskii, N. V.; Kulakov, E. V.; Kleshchevnikov, O. A.; Antipov, M. V.; Yurtov, I. V.; Rudnev, A. V.; Chapaev, A. V.; Pupkov, A. S.; Sen'kovskii, E. D.; Sotskov, E. A.; Glushikhin, V. V.; Kalashnik, I. A.; Finyushin, S. A.; Chudakov, E. A.; Kalashnikov, D. A.

    2016-08-01

    In view of the possible effect of contamination of a plasma by metal particles on the operation of a number of facilities or on the detection of the motion of liners by Doppler methods, a particular attention has been recently focused on the problem of the ejection of particles from the shock-loaded free surface of a sample or on the "dusting" problem. Most information concerns the dusting source associated with the roughness of the surface, manufacturing technology, and the defectiveness and aging of a material. Factors affecting this process such as the profile and amplitude of the pressure on the front of the shock wave arriving at the free surface of the sample, the presence of the gas in front of the free surface, and the pressure in this gas are less studied.

  17. Precompression and desensitization of a high explosive by trapped gas in plate impacts--new measurements

    SciTech Connect

    Anderson, W. W.; Fritz, J. N.; Kennedy, J. E.; Shaw, S. M.

    2002-01-01

    It has long been known that trapped gas between an impactor and high explosive will precompress a layer of the explosive. Most quantitative studies measure the resulting decrease in shock sensitivity. There have been no studies really aimed at measuring the properties of the precompressed layer. Experiments at Los Alamos originally to study release behavior allow the layer to be probed in PBX 9502 (95% TATB, 5% KeI-F 800).

  18. A CHANDRA STUDY OF THE LARGE-SCALE SHOCK AND COOL FILAMENTS IN HYDRA A: EVIDENCE FOR SUBSTANTIAL GAS DREDGE-UP BY THE CENTRAL OUTBURST

    SciTech Connect

    Gitti, Myriam; Nulsen, Paul E. J.; David, Laurence P.; McNamara, Brian R.; Wise, Michael W.

    2011-05-01

    We present the results of a Chandra study of the Hydra A galaxy cluster, where a powerful active galactic nucleus (AGN) outburst created a large-scale cocoon shock. We investigated possible azimuthal variations in shock strength and shape, finding indications for a weak shock with a Mach number in the range {approx}1.2-1.3. We measured the temperature change across the shock front. However, the detection of a temperature rise in the regions immediately inside of the front is complicated by the underlying temperature profile of the cluster atmosphere. We measured the global temperature profile of the cluster up to 700 kpc, which represents the farthest measurement obtained with Chandra for this cluster. A 'plateau' in the temperature profile in the range {approx}70-150 kpc indicates the presence of cool gas, which is likely the result of uplift of material by the AGN outburst. After masking the cool filaments visible in the hardness ratio map, the plateau disappears and the temperature profile recovers a typical shape with a peak around 190 kpc, just inside the shock front. However, it is unlikely that such a temperature feature is produced by the shock as it is consistent with the general shape of the temperature profiles observed for relaxed galaxy clusters. We studied the spectral properties of the cool filaments finding evidence that {approx}10{sup 11} M{sub sun} of low-entropy material has been dredged up by the rising lobes from the central 30 kpc to the observed current position of 75-150 kpc. The energy required to lift the cool gas is {approx}> 2.2 x 10{sup 60} erg, which is comparable to the work required to inflate the cavities and is {approx}25% of the total energy of the large-scale shock. Our results show that the AGN feedback in Hydra A is acting not only by directly heating the gas, but also by removing a substantial amount of potential fuel for the supermassive black hole.

  19. Radiative Shock Waves In Emerging Shocks

    NASA Astrophysics Data System (ADS)

    Drake, R. Paul; Doss, F.; Visco, A.

    2011-05-01

    In laboratory experiments we produce radiative shock waves having dense, thin shells. These shocks are similar to shocks emerging from optically thick environments in astrophysics in that they are strongly radiative with optically thick shocked layers and optically thin or intermediate downstream layers through which radiation readily escapes. Examples include shocks breaking out of a Type II supernova (SN) and the radiative reverse shock during the early phases of the SN remnant produced by a red supergiant star. We produce these shocks by driving a low-Z plasma piston (Be) at > 100 km/s into Xe gas at 1.1 atm. pressure. The shocked Xe collapses to > 20 times its initial density. Measurements of structure by radiography and temperature by several methods confirm that the shock wave is strongly radiative. We observe small-scale perturbations in the post-shock layer, modulating the shock and material interfaces. We describe a variation of the Vishniac instability theory of decelerating shocks and an analysis of associated scaling relations to account for the growth of these perturbations, identify how they scale to astrophysical systems such as SN 1993J, and consider possible future experiments. Collaborators in this work have included H.F. Robey, J.P. Hughes, C.C. Kuranz, C.M. Huntington, S.H. Glenzer, T. Doeppner, D.H. Froula, M.J. Grosskopf, and D.C. Marion ________________________________ * Supported by the US DOE NNSA under the Predictive Sci. Academic Alliance Program by grant DE-FC52-08NA28616, the Stewardship Sci. Academic Alliances program by grant DE-FG52-04NA00064, and the Nat. Laser User Facility by grant DE-FG03-00SF22021.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  1. Shock-wave flow regimes at entry into the diffuser of a hypersonic ramjet engine: Influence of physical properties of the gas medium

    NASA Astrophysics Data System (ADS)

    Tarnavskii, G. A.

    2006-07-01

    The physical aspects of the effective-adiabatic-exponent model making it possible to decompose the total problem on modeling of high-velocity gas flows into individual subproblems (“physicochemical processes” and “ aeromechanics”), which ensures the creation of a universal and efficient computer complex divided into a number of independent units, have been analyzed. Shock-wave structures appearing at entry into the duct of a hypersonic aircraft have been investigated based on this methodology, and the influence of the physical properties of the gas medium in a wide range of variations of the effective adiabatic exponent has been studied.

  2. Structure in Radiating Shocks

    NASA Astrophysics Data System (ADS)

    Doss, Forrest

    2010-11-01

    The basic radiative shock experiment is a shock launched into a gas of high-atomic-number material at high velocities, which fulfills the conditions for radiative losses to collapse the post-shock material to over 20 times the initial gas density. This has been accomplished using the OMEGA Laser Facility by illuminating a Be ablator for 1 ns with a total of 4 kJ, launching the requisite shock, faster than 100 km/sec, into a polyimide shock tube filled with Xe. The experiments have lateral dimensions of 600 μm and axial dimensions of 2-3 mm, and are diagnosed by x-ray backlighting. Repeatable structure beyond the one-dimensional picture of a shock as a planar discontinuity was discovered in the experimental data. One form this took was that of radial boundary effects near the tube walls, extended approximately seventy microns into the system. The cause of this effect - low density wall material which is heated by radiation transport ahead of the shock, launching a new converging shock ahead of the main shock - is apparently unique to high-energy-density experiments. Another form of structure is the appearance of small-scale perturbations in the post-shock layer, modulating the shock and material interfaces and creating regions of enhanced and diminished aerial density within the layer. The authors have applied an instability theory, a variation of the Vishniac instability of decelerating shocks, to describe the growth of these perturbations. We have also applied Bayesian statistical methods to better understand the uncertainties associated with measuring shocked layer thickness in the presence of tilt. Collaborators: R. P. Drake, H. F. Robey, C. C. Kuranz, C. M. Huntington, M. J. Grosskopf, D. C. Marion.

  3. Shocked and Scorched - Free-Floating Evaporating Gas Globules and Star Formation

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra; Morris, Mark R.; Claussen, Mark J.

    2014-07-01

    Massive stars have a strong feedback effect on their environment, via their winds, UV radiation, and ultimately, supernova blast waves, all of which can alter the likelihood for the formation of stars in nearby clouds and limit the accretion process of nearby protostars. Free-floating Evaporating Gaseous Globules, or frEGGs, are a newly recognized class of stellar nurseries embedded within the giant HII regions found in massive star-formation region (MSFRs). We recently discovered the prototype frEGG in the Cygnus MSFR with HST. Further investigation using the Spitzer and Herschel archives have revealed a much larger number (>50) in Cygnus and other MSFRs. Our molecular-line observations of these show the presence of dense clouds with total masses of cool molecular gas exceeding 0.5 to a few Msun associated with these objects, thereby disproving the initial hypothesis based on their morphology that these have an origin similar to the proplyds (cometary-shaped photoevaporating protoplanetary disks) found in Orion. We report the results of our molecular-line studies and detailed high-resolution optical (with HST) or near-IR (with AO at the Keck Observatory) imaging of a few frEGGs in Cygnus, Carina and the W5 MSFRs. The images show the presence of young stars with associated outflow cavities and/or jets in the heads of the tadpole-shaped frEGGs. These results support our hypothesis that frEGGs are density concentrations originating in giant molecular clouds, that, when subject to the compression by the strong winds and ionization from massive stars in these MSFRs, become active star-forming cores. In summary, by virtue of their distinct, isolated morphologies, frEGGs offer us a clean probe of triggered star formation on small scales in the vicinity of massive stars.

  4. Los Alamos National Laboratory

    SciTech Connect

    Dogliani, Harold O

    2011-01-19

    The purpose of the briefing is to describe general laboratory technical capabilities to be used for various groups such as military cadets or university faculty/students and post docs to recruit into a variety of Los Alamos programs. Discussed are: (1) development and application of high leverage science to enable effeictive, predictable and reliability outcomes; (2) deter, detect, characterize, reverse and prevent the proliferation of weapons of mass destruction and their use by adversaries and terrorists; (3) modeling and simulation to define complex processes, predict outcomes, and develop effective prevention, response, and remediation strategies; (4) energetic materials and hydrodynamic testing to develop materials for precise delivery of focused energy; (5) materials cience focused on fundamental understanding of materials behaviors, their quantum-molecular properties, and their dynamic responses, and (6) bio-science to rapidly detect and characterize pathogens, to develop vaccines and prophylactic remedies, and to develop attribution forensics.

  5. New constraints on the sulfur reservoir in the dense interstellar medium provided by Spitzer observations of S I in shocked gas

    SciTech Connect

    Anderson, Dana E.; Bergin, Edwin A.; Maret, Sébastien

    2013-12-20

    We present observations of fine-structure line emission of atomic sulfur, iron, and rotational lines of molecular hydrogen in shocks associated with several Class 0 protostars obtained with the Infrared Spectrograph of the Spitzer Space Telescope. We use these observations to investigate the 'missing sulfur problem', that significantly less sulfur is found in dense regions of the interstellar medium (ISM) than in diffuse regions. For sources where the sulfur fine-structure line emission is co-spatial with the detected molecular hydrogen emission and in the presence of weak iron emission, we derive sulfur and H{sub 2} column densities for the associated molecule-dominated C-shocks. We find the S I abundance to be ≳5%-10% of the cosmic sulfur abundance, indicating that atomic sulfur is a major reservoir of sulfur in shocked gas. This result suggests that in the quiescent dense ISM sulfur is present in some form that is released from grains as atoms, perhaps via sputtering, within the shock.

  6. Quantum shock waves and domain walls in the real-time dynamics of a superfluid unitary Fermi gas.

    PubMed

    Bulgac, Aurel; Luo, Yuan-Lung; Roche, Kenneth J

    2012-04-13

    We show that in the collision of two superfluid fermionic atomic clouds one observes the formation of quantum shock waves as discontinuities in the number density and collective flow velocity. Domain walls, which are topological excitations of the superfluid order parameter, are also generated and exhibit abrupt phase changes by π and slower motion than the shock waves. The domain walls are distinct from the gray soliton train or number density ripples formed in the wake of the shock waves and observed in the collisions of superfluid bosonic atomic clouds. Domain walls with opposite phase jumps appear to collide elastically.

  7. Cardiogenic shock

    MedlinePlus

    Shock - cardiogenic ... electrical system of the heart (heart block) Cardiogenic shock occurs when the heart is unable to pump ... orthostatic hypotension) Weak (thready) pulse To diagnose cardiogenic shock, a catheter (tube) may be placed in the ...

  8. Fabrication of graded density impactor via underwater shock wave and quasi-isentropic compression testing at two-stage gas gun facility

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Li, Xiaojie; Hokamoto, Kazuyuki

    2014-12-01

    We show direct evidence that underwater shock wave enables us to bond multithin plates with flat, parallel, and high-strength interfaces, which are key requirements for functionally graded material (also called graded density impactor). This phenomenon is ascribed to the super short duration of the high-speed underwater shock wave, reducing the surface tension, diffusion, evaporation, deposition, and viscous flow of matter. Thin magnesium, aluminum, titanium, copper, and molybdenum foils were welded together and designed with the increase in density. Experimental evidence and numerical simulation show that well bonding between the multilayer structures. Microstructure examinations reveal that the dominant interfacial form shifts from waviness to linearity. Graded density impactor with multilayer structure is proved that can produce quasi-isentropic compression in two-stage gas gun experiment with a designed pressure loading profile, which suggests a feasible method to simulate the conditions we want to study that were previously inaccessible in a precisely controlled laboratory environment.

  9. ASC platforms at Los Alamos.

    SciTech Connect

    Shaw, S. R.

    2004-01-01

    This talk describes the history, current state, and future plans for ASC computational and data storage service at Los Alamos. The of the systems and services described is limited to those installed in and managed by Group CCN-7.

  10. Los Alamos National Laboratory Overview

    SciTech Connect

    Neu, Mary

    2010-06-02

    Mary Neu, Associate Director for Chemistry, Life and Earth Sciences at Los Alamos National Laboratory, delivers opening remarks at the "Sequencing, Finishing, Analysis in the Future" meeting in Santa Fe, NM

  11. Fast and Furious: Shock heated gas as the origin of spatially resolved hard X-ray emission in the central 5 kpc of the galaxy merger NGC 6240

    SciTech Connect

    Wang, Junfeng; Nardini, Emanuele; Fabbiano, Giuseppina; Karovska, Margarita; Elvis, Martin; Risaliti, Guido; Zezas, Andreas; Pellegrini, Silvia; Max, Claire; U, Vivian

    2014-01-20

    We have obtained a deep, subarcsecond resolution X-ray image of the nuclear region of the luminous galaxy merger NGC 6240 with Chandra, which resolves the X-ray emission from the pair of active nuclei and the diffuse hot gas in great detail. We detect extended hard X-ray emission from kT ∼ 6 keV (∼70 MK) hot gas over a spatial scale of 5 kpc, indicating the presence of fast shocks with a velocity of ∼2200 km s{sup –1}. For the first time, we obtain the spatial distribution of this highly ionized gas emitting Fe XXV, which shows a remarkable correspondence to the large-scale morphology of H{sub 2}(1-0) S(1) line emission and Hα filaments. Propagation of fast shocks originating in the starburst-driven wind into the ambient dense gas can account for this morphological correspondence. With an observed L {sub 0.5-8} {sub keV} = 5.3 × 10{sup 41} erg s{sup –1}, the diffuse hard X-ray emission is ∼100 times more luminous than that observed in the classic starburst galaxy M82. Assuming a filling factor of 1% for the 70 MK temperature gas, we estimate its total mass (M {sub hot} = 1.8 × 10{sup 8} M {sub ☉}) and thermal energy (E {sub th} = 6.5 × 10{sup 57} erg). The total iron mass in the highly ionized plasma is M {sub Fe} = 4.6 × 10{sup 5} M {sub ☉}. Both the energetics and the iron mass in the hot gas are consistent with the expected injection from the supernovae explosion during the starburst that is commensurate with its high star formation rate. No evidence for fluorescent Fe I emission is found in the CO filament connecting the two nuclei.

  12. Fast and Furious: Shock Heated Gas as the Origin of Spatially Resolved Hard X-Ray Emission in the Central 5 kpc of the Galaxy Merger NGC 6240

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng; Nardini, Emanuele; Fabbiano, Giuseppina; Karovska, Margarita; Elvis, Martin; Pellegrini, Silvia; Max, Claire; Risaliti, Guido; U, Vivian; Zezas, Andreas

    2014-01-01

    We have obtained a deep, subarcsecond resolution X-ray image of the nuclear region of the luminous galaxy merger NGC 6240 with Chandra, which resolves the X-ray emission from the pair of active nuclei and the diffuse hot gas in great detail. We detect extended hard X-ray emission from kT ~ 6 keV (~70 MK) hot gas over a spatial scale of 5 kpc, indicating the presence of fast shocks with a velocity of ~2200 km s-1. For the first time, we obtain the spatial distribution of this highly ionized gas emitting Fe XXV, which shows a remarkable correspondence to the large-scale morphology of H2(1-0) S(1) line emission and Hα filaments. Propagation of fast shocks originating in the starburst-driven wind into the ambient dense gas can account for this morphological correspondence. With an observed L 0.5-8 keV = 5.3 × 1041 erg s-1, the diffuse hard X-ray emission is ~100 times more luminous than that observed in the classic starburst galaxy M82. Assuming a filling factor of 1% for the 70 MK temperature gas, we estimate its total mass (M hot = 1.8 × 108 M ⊙) and thermal energy (E th = 6.5 × 1057 erg). The total iron mass in the highly ionized plasma is M Fe = 4.6 × 105 M ⊙. Both the energetics and the iron mass in the hot gas are consistent with the expected injection from the supernovae explosion during the starburst that is commensurate with its high star formation rate. No evidence for fluorescent Fe I emission is found in the CO filament connecting the two nuclei.

  13. When shock waves collide

    DOE PAGES

    Martinez, D.; Hartigan, P.; Frank, A.; Hansen, E.; Yirak, K.; Liao, A. S.; Graham, P.; Foster, J.; Wilde, B.; Blue, B.; et al

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed tomore » quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. Furthermore, the experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.« less

  14. When Shock Waves Collide

    NASA Astrophysics Data System (ADS)

    Hartigan, P.; Foster, J.; Frank, A.; Hansen, E.; Yirak, K.; Liao, A. S.; Graham, P.; Wilde, B.; Blue, B.; Martinez, D.; Rosen, P.; Farley, D.; Paguio, R.

    2016-06-01

    Supersonic outflows from objects as varied as stellar jets, massive stars, and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system reconfigures its geometry to create a normal shock known as a Mach stem where the shocks meet. Mach stems are important for interpreting emission-line images of shocked gas because a normal shock produces higher postshock temperatures, and therefore a higher-excitation spectrum than does an oblique shock. In this paper, we summarize the results of a series of numerical simulations and laboratory experiments designed to quantify how Mach stems behave in supersonic plasmas that are the norm in astrophysical flows. The experiments test analytical predictions for critical angles where Mach stems should form, and quantify how Mach stems grow and decay as intersection angles between the incident shock and a surface change. While small Mach stems are destroyed by surface irregularities and subcritical angles, larger ones persist in these situations and can regrow if the intersection angle changes to become more favorable. The experimental and numerical results show that although Mach stems occur only over a limited range of intersection angles and size scales, within these ranges they are relatively robust, and hence are a viable explanation for variable bright knots observed in Hubble Space Telescope images at the intersections of some bow shocks in stellar jets.

  15. Self-similar flow of a rotating dusty gas behind the shock wave with increasing energy, conduction and radiation heat flux

    NASA Astrophysics Data System (ADS)

    Nath, G.

    2012-01-01

    A self-similar solution is obtained for one dimensional adiabatic flow behind a cylindrical shock wave propagating in a rotating dusty gas in presence of heat conduction and radiation heat flux with increasing energy. The dusty gas is assumed to be a mixture of non-ideal (or perfect) gas and small solid particles, in which solid particles are continuously distributed. It is assumed that the equilibrium flow-condition is maintained and variable energy input is continuously supplied by the piston (or inner expanding surface). The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature only. In order to obtain the similarity solutions the initial density of the ambient medium is assumed to be constant and the angular velocity of the ambient medium is assumed to be decreasing as the distance from the axis increases. The effects of the variation of the heat transfer parameters and non-idealness of the gas in the mixture are investigated. The effects of an increase in (i) the mass concentration of solid particles in the mixture and (ii) the ratio of the density of solid particles to the initial density of the gas on the flow variables are also investigated.

  16. Numerical solution of the hypersonic viscous-shock-layer equations for laminar, transitional, and turbulent flows of a perfect gas over blunt axially symmetric bodies

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations applicable to hypersonic laminar, transitional, and turbulent flows of a perfect gas over two-dimensional plane or axially symmetric blunt bodies are presented. The equations are solved by means of an implicit finite difference scheme, and the results are compared with a turbulent boundary layer analysis. The agreement between the two solution procedures is satisfactory for the region of flow where streamline swallowing effects are negligible. For the downstream regions, where streamline swallowing effects are present, the expected differences in the two solution procedures are evident.

  17. Embedded Electromagnetic Gauge Measurements and Modeling of Shock Initiation in the TATB Based Explosives LX-17 and PBX 9502

    NASA Astrophysics Data System (ADS)

    Gustavsen, R. L.; Sheffield, S. A.; Alcon, R. R.; Forbes, J. W.; Tarver, C. M.; Garcia, F.

    2002-07-01

    We have completed a series of shock initiation experiments on PBX 9502 (95 weight % dry aminated TATB explosive, 5 weight % Kel-F 800 binder) and LX-17 (92.% wet aminated TATB, 7.5 % Kel-F 800). These experiments were performed on the gas/gas two stage gun at Los Alamos. Samples were prepared with ten or eleven embedded electromagnetic particle velocity gauges to measure the evolution of the wave leading up to a detonation. Additionally, one to three shock tracker gauges were used to track the position of the shock front with time and determine the point where detonation was achieved. Wave profiles indicate little delay between formation of hot-spots in the shock front and release of hot-spot energy. In other words, a great deal of the buildup occurs in the shock front, rather than behind it. Run distances and times to detonation as a function of initial pressure are consistent with published data. The Ignition and Growth model with published parameters for LX-17 replicate the data very well.

  18. Embedded Electromagnetic Gauge Measurements and Modeling of Shock Initiation in the TATB based Explosives PBX 9502 and LX-17

    NASA Astrophysics Data System (ADS)

    Gustavsen, R. L.; Sheffield, S. A.; Alcon, R. R.; Forbes, J. W.; Tarver, C. M.; Garcia, F.

    2001-06-01

    We have completed a series of shock initiation experiments on PBX 9502 (95 weight % dry aminated TATB explosive, 5 weight % Kel-F 800 binder) and LX-17 (92.5 % wet aminated TATB, 7.5 % Kel-F 800). These experiments were performed on the gas/gas two stage gun at Los Alamos. Samples were prepared with 10 - 11 embedded electromagnetic particle velocity gauges to measure the evolution of the wave leading up to a detonation. Additionally, 1 to 3 shock tracker gauges were used to track the position of the shock front with time and determine the point where detonation was achieved. Wave profiles indicate little delay between formation of hot-spots in the shock front and release of hot-spot energy. In other words, a great deal of the buildup occurs in the shock front, rather than behind it. Run distances and times to detonation as a function of initial pressure are consistent with published data. The Ignition and Growth model with published parameters for LX-17 replicate the data very well.

  19. Propagation of a spherical shock wave in mixture of non-ideal gas and small solid particles under the influence of gravitational field with conductive and radiative heat fluxes

    NASA Astrophysics Data System (ADS)

    Nath, G.

    2016-01-01

    Self-similar solutions are obtained for one-dimensional unsteady adiabatic flow behind a spherical shock wave propagating in a dusty gas with conductive and radiative heat fluxes under the influence of a gravitational field. The shock is assumed to be driven out by a moving piston and the dusty gas to be a mixture of non-ideal gas and small solid particles, in which solid particles are uniformly distributed. It is assumed that the equilibrium flow-conditions are maintained and variable energy input is continuously supplied by the piston. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature and density. The medium is assumed to be under the influence of a gravitational field due to central mass ( bar{m} ) at the origin (Roche Model). It is assumed that the gravitational effect of the mixture itself can be neglected compared with the attraction of the central mass. The initial density of the ambient medium is taken to be always constant. The effects of the variation of the gravitational parameter and nonidealness of the gas in the mixture are investigated. Also, the effects of an increase in (i) the mass concentration of solid particles in the mixture and (ii) the ratio of the density of solid particles to the initial density of the gas on the flow variables are investigated. It is shown that due to an increase in the gravitational parameter the compressibility of the medium at any point in the flow-field behind the shock decreases and all other flow variables and the shock strength are increased. Further, it is found that the presence of gravitational field increases the compressibility of the medium, due to which it is compressed and therefore the distance between the piston and the shock surface is reduced. The shock waves in dusty gas under the influence of a

  20. FISICA Integral Field Spectroscopy of the Shocked Iron Gas in the Supernova Remnant G11.2--0.3

    NASA Astrophysics Data System (ADS)

    Moon, Dae-Sik; Eikenberry, Stephen S.; Koo, Bon-Chul; Raines, S. Nicholas; Gruel, Nicolas

    2006-02-01

    We have recently discovered strong iron line ([Fe II] (lambda)1.644 (mu)m) emission in the young supernova remnant G11.2-0.3. The iron line emission occurs at the south-eastern shell edge of G11.2-0.3, and positionally overlaps with the very strong X-ray and radio emission of the supernova remnant. The iron line emission is most likely caused by the shock acceleration of G11.2-0.3 interacting with the ambient medium. We propose to carry out JH-band integral-field spectroscopy of the two iron line clumps in G11.2-0.3 with FISICA, an image-slicing integral-field unit for FLAMINGOS, which will give us a uniquely comprehensive view of the strong shock acceleration of a SNR.

  1. A single-pulse shock tube coupled with high-repetition-rate time-of-flight mass spectrometry and gas chromatography for high-temperature gas-phase kinetics studies

    NASA Astrophysics Data System (ADS)

    Sela, P.; Shu, B.; Aghsaee, M.; Herzler, J.; Welz, O.; Fikri, M.; Schulz, C.

    2016-10-01

    Shock tubes are frequently used to investigate the kinetics of chemical reactions in the gas phase at high temperatures. Conventionally, two complementary arrangements are used where either time-resolved intermediate species measurements are conducted after the initiation of the reaction or where the product composition is determined after rapid initiation and quenching of the reaction through gas-dynamic processes. This paper presents a facility that combines both approaches to determine comprehensive information. A single-pulse shock tube is combined with high-sensitivity gas chromatography/mass spectrometry for product composition and concentration measurement as well as high-repetition-rate time-of-flight mass spectrometry for time-dependent intermediate concentration determination with 10 μs time resolution. Both methods can be applied simultaneously. The arrangement is validated with investigations of the well-documented thermal unimolecular decomposition of cyclohexene towards ethylene and 1,3-butadiene at temperatures between 1000 and 1500 K and pressures ranging from 0.8 to 2.4 bars. The comparison shows that the experimental results for both detections are in very good agreement with each other and with literature data.

  2. Post-Shock Temperature Measurements of Aluminum

    SciTech Connect

    Seifter, A.; Furlanetto, M. R.; Payton, J. R.; Obst, A. W.; Stewart, S. T.; Kennedy, G. B.

    2006-07-28

    Post-shock temperature is an important quantity in shock physics experiments for constraining the dynamic equations of state of materials. A high-speed, infrared, multi-wavelength pyrometer has been developed at Los Alamos National Laboratory (LANL) for measurements in the temperature range from 400 to 1200 K. With customized front end optics, permitting concurrent VISAR measurements in the same optical path, validation experiments on aluminum have been conducted at the new Shock Compression Laboratory at Harvard University. Under <1 millitorr vacuum, a post-shock temperature of 495 K {+-} 30 K was recorded from a polished free surface of aluminum 2024-T4 subject to a peak shock pressure of 34.8{+-}0.8 GPa, in excellent agreement with the equation of state and previous experiments.

  3. Direct-current proton-beam measurements at Los Alamos

    SciTech Connect

    Sherman, Joseph; Stevens, Ralph R.; Schneider, J. David; Zaugg, Thomas

    1995-09-15

    Recently, a CW proton accelerator complex was moved from Chalk River Laboratories (CRL) to Los Alamos National Laboratory. This includes a 50-keV dc proton injector with a single-solenoid low-energy beam transport system (LEBT) and a CW 1.25-MeV, 267-MHz radiofrequency quadrupole (RFQ). The move was completed after CRL had achieved 55-mA CW operation at 1.25 MeV using 250-kW klystrode tubes to power the RFQ. These accelerator components are prototypes for the front end of a CW linac required for an accelerator-driven transmutation linac, and they provide early confirmation of some CW accelerator components. The injector (ion source and LEBT) and emittance measuring unit are installed and operational at Los Alamos. The dc microwave ion source has been operated routinely at 50-keV, 75-mA hydrogen-ion current. This ion source has demonstrated very good discharge and H2 gas efficiencies, and sufficient reliability to complete CW RFQ measurements at CRL. Proton fraction of 75% has been measured with 550-W discharge power. This high proton fraction removes the need for an analyzing magnet. Proton LEBT emittance measurements completed at Los Alamos suggest that improved transmission through the RFQ may be achieved by increasing the solenoid focusing current. Status of the final CW RFQ operation at CRL and the installation of the RFQ at Los Alamos will be given.

  4. Direct-current proton-beam measurements at Los Alamos

    SciTech Connect

    Sherman, J.; Stevens, R.R.; Schneider, J.D.; Zaugg, T.

    1994-08-01

    Recently, a CW proton accelerator complex was moved from Chalk River Laboratories (CRL) to Los Alamos National Laboratory. This includes a 50-keV dc proton injector with a single-solenoid low-energy beam transport system (LEBT) and a CW 1.25-MeV, 267-MHz radiofrequency quadrupole (RFQ). The move was completed after CRL had achieved 55-mA CW operation at 1.25 MeV using 250-kW klystrode tubes to power the RFQ. These accelerator components are prototypes for the front end of a CW linac required for an accelerator-driven transmutation linac, and they provide early confirmation of some CW accelerator components. The injector (ion source and LEBT) and emittance measuring unit are installed and operational at Los Alamos. The dc microwave ion source has been operated routinely at 50-keV, 75-mA hydrogen-ion current. This ion source has demonstrated very good discharge and H{sub 2} gas efficiencies, and sufficient reliability to complete CW RFQ measurements at CRL. Proton fraction of 75% has been measured with 550-W discharge power. This high proton fraction removes the need for an analyzing magnet. Proton LEBT emittance measurements completed at Los Alamos suggest that improved transmission through the RFQ may be achieved by increasing the solenoid focusing current. Status of the final CW RFQ operation at CRL and the installation of the RFQ at Los Alamos is given.

  5. [High resolution laser transient spectroscopic technology under two-stage light gas-gun loading condition and stability study of shocked benzene].

    PubMed

    Zhao, Bei-Jing; Liu, Fu-Sheng; Wang, Wen-Peng; Zhang, Ning-Chao; Feng, Li-Peng; Zhang, Ming-Jian; Xue, Xue-Dong

    2013-10-01

    The present paper reports the high resolution transient Raman laser testing technology under two-stage light gas-gun loading experiment, and its application to studying the Raman spectroscopy of shocked benzene. In the experiments, the frequency shift of C-C stretching vibration (992 cm(-1)) and C-H stretching vibration peak (3 061 cm(-1)) in the low pressure section (less than 8 GPa) varies linearly with the pressure, and the results agree well with reported data in the literature. The structural changes in liquid benzene about 13 GPa were clarified firstly by the Raman spectral technique; the experimental results show that at a pressure of 9.7 GPa, the structural change of liquid benzene has taken place, not reported in the literature about 13 GPa. But the composition in the production is not clear. The measurement system provides an effective means to study the microstructure changes of transparent and translucent material under dynamic loading experiment.

  6. Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration

    NASA Technical Reports Server (NTRS)

    Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

    1973-01-01

    The vibration response of a gas-bearing rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental bearing surface contacts) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust bearing runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-bearing shock response.

  7. Shock wave emergence at the stellar surface and the subsequent gas expansion into a vacuum - The sphericity involvement

    NASA Astrophysics Data System (ADS)

    Kazhdan, Ia. M.; Murzina, Marina

    1992-11-01

    Attention is given to a solution to describe the shock wave passage through the outer envelope of the star and the following stellar matter expansion into a vacuum. The solution takes into account the sphericity of the flow in the neighborhood of the stellar surface. Calculations are performed for the case gamma = 4/3, n = 3 (gamma is the adiabatic index, and n is the peripheric politropic index). At the stage of the shock wave emergence, the sphericity is shown to affect mostly the spatial distributions of density and pressure by increasing their slopes from the surface to the center of the star. For the stage of matter expansion, the solution describes the pressure-dominated acceleration of the outer envelope at arbitrary moments of time even up to t approaches infinity, and prolongs the analytical treatment of the envelope dynamics up to the stage of free expansion, contrary to the plane-approximation consideration. The sphericity results in decreasing pressure, density, and velocity of Lagrangian layers.

  8. Calculating Flows With Interfering Shock Waves

    NASA Technical Reports Server (NTRS)

    Glass, Christopher E.

    1993-01-01

    Equilibrium Air Shock Interference, EASI, program takes account of dissociation of air molecules. Revives and updates older computational methods for calculating inviscid flow field and maximum heating from interference of shock waves. Expands methods to solve problems involving six shock-wave interference patterns on two-dimensional cylindrical leading edge with equilibrium, chemically-reacting gas mixture. Written in FORTRAN 77.

  9. Los Alamos Critical Assemblies Facility

    SciTech Connect

    Malenfant, R.E.

    1981-06-01

    The Critical Assemblies Facility of the Los Alamos National Laboratory has been in existence for thirty-five years. In that period, many thousands of measurements have been made on assemblies of /sup 235/U, /sup 233/U, and /sup 239/Pu in various configurations, including the nitrate, sulfate, fluoride, carbide, and oxide chemical compositions and the solid, liquid, and gaseous states. The present complex of eleven operating machines is described, and typical applications are presented.

  10. [Cardiogenic shock].

    PubMed

    Houegnifioh, Komlanvi Kafui; Gfeller, Etienne; Garcia, Wenceslao; Ribordy, Vincent

    2014-08-13

    Cardiogenic shock, especially when it complicates a myocardial infarction, is still associated with high mortality rate. Emergency department or first care physicians are often the first providers to assess the cardiogenic shock patient, and plays thereby a key role in achieving a timely diagnosis and treatment. This review will detail the actual physiopathology understanding of the cardiogenic shock, its diagnosis and management focusing on the care within the emergency department.

  11. Technology-Based Oil and Natural Gas Plays: Shale Shock! Could There Be Billions in the Bakken?

    EIA Publications

    2006-01-01

    This report presents information about the Bakken Formation of the Williston Basin: its location, production, geology, resources, proved reserves, and the technology being used for development. This is the first in a series intending to share information about technology-based oil and natural gas plays.

  12. Limiting Temperatures of Spherical Shock Wave Implosion.

    PubMed

    Liverts, Michael; Apazidis, Nicholas

    2016-01-01

    Spherical shock wave implosion in argon is studied both theoretically and experimentally. It is shown that as the strength of the converging shock increases the nonideal gas effects become dominant and govern the evolution of thermal and transport gas properties limiting the shock acceleration, lowering the gas adiabatic index and the achievable energy density at the focus. Accounting for multiple-level ionization, excitation, Coulomb interaction and radiation effects, the limiting equilibrium temperatures to be achieved during the shock implosion are estimated. Focal temperatures of the order of 30 000 K are measured in experiments where converging spherical shock waves are created using a conventional gas-dynamic shock tube facility. PMID:26799021

  13. Los Alamos Science: Number 16

    SciTech Connect

    Cooper, N.G.

    1988-01-01

    It was an unusually stimulating day and a half at Los Alamos when two Nobel Laureates in physiology, a leading paleontologist, and a leading bio-astrophysicist came together to discuss ''Unsolved Problems in the Science of Life,'' the topic of the second in a series of special meetings sponsored by the Fellows of the Laboratory. Just like the first one on ''Creativity in Science,'' this colloquium took us into a broader arena of ideas and viewpoints than is our usual daily fare. To contemplate the evolution and mysteries of intelligent life from the speakers' diverse points of view at one time, in one place was indeed a rare experience.

  14. Cardiogenic shock.

    PubMed

    Shah, Palak; Cowger, Jennifer A

    2014-07-01

    Cardiogenic shock is the most common cause of in-hospital mortality for patients who have suffered a myocardial infarction. Mortality exceeds 50% and management is focused on a rapid diagnosis of cardiogenic shock, restoration of coronary blood flow through early revascularization, complication management, and maintenance of end-organ homeostasis. Besides revascularization, inotropes and vasodilators are potent medical therapies to assist the failing heart. Pulmonary arterial catheters are an important adjunctive tool to assess patient hemodynamics, but their use should be limited to select patients in cardiogenic shock.

  15. Laser-Launched Flyer Plates and Direct Laser Shocks for Dynamic Material Property Measurements

    NASA Astrophysics Data System (ADS)

    Paisley, D. L.; Swift, D. C.; Johnson, R. P.; Kopp, R. A.; Kyrala, G. A.

    2002-07-01

    The Trident laser at Los Alamos was used to impart known and controlled shocks in various materials by launching flyer plates or by irradiating the sample directly. Materials investigated include copper, gold, NiTi, SS316, and other metals and alloys. Tensile spall strength, elastic-plastic transition, phase boundaries, and equation of state can be determined with small samples. Using thin samples (0.1 - 1.0 mm thick) as targets, high pressure gradients can be generated with relatively low pressures, resulting in high tensile strain rates (105 to 108 s-1). Free surface and interface velocities are recorded with point- and line-imaging VISARs. The flexible spatial and temporal pulse profiles of Trident, coupled with the use of laser-launched flyer plates, provides capabilities which complement experiments conducted using gas guns and tensile bars.

  16. Electron velocity distributions near the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Feldman, W. C.; Anderson, R. C.; Bame, S. J.; Gary, S. P.; Gosling, J. T.; Mccomas, D. J.; Thomsen, M. F.; Paschmann, G.; Hoppe, M. M.

    1983-01-01

    New information is presented on the general characteristics of electron distribution functions upstream, within, and downstream of the earth's bow shock, thereby providing new insights into the instabilities in collisionless shocks. The results presented are from a survey of electron velocity distributions measured near the earth's bow shock between October 1977 and December 1978 using the Los Alamos/Garching plasma instrumentation aboard ISEE 2. A wide variety of distribution shapes is found within the different plasma regions in close proximity to the bow shock. It is found that these shapes can be classified into general types that are characteristic of three different plasma regions, namely the upstream region or electron foreshock, the shock proper where most of the heating occurs, and the downstream region or the magnetosheath. Evidence is provided that field-aligned, rather than cross-field, instabilities are the major source of electron dissipation in the earth's bow shock.

  17. Cosmic-ray shock acceleration in oblique MHD shocks

    NASA Technical Reports Server (NTRS)

    Webb, G. M.; Drury, L. OC.; Volk, H. J.

    1986-01-01

    A one-dimensional, steady-state hydrodynamical model of cosmic-ray acceleration at oblique MHD shocks is presented. Upstream of the shock the incoming thermal plasma is subject to the adverse pressure gradient of the accelerated particles, the J x B force, as well as the thermal gas pressure gradient. The efficiency of the acceleration of cosmic-rays at the shock as a function of the upstream magnetic field obliquity and upstream plasma beta is investigated. Astrophysical applications of the results are briefly discussed.

  18. Los Alamos opacity web page

    SciTech Connect

    Magee, N.H. Jr.; Clark, R.E.H.

    1998-02-01

    The Los Alamos opacity data base is now available on the World Wide Web at http://t4.lanl.gov. The data base contains both the original Astrophysical Opacity Library distributed worldwide in the 1980`s (for historical reference) and the new improved opacities from the Light Element Detailed Configuration OPacity (LEDCOP) code. Users can access the opacity data using the multigroup opacity code TOPS to obtain Rosseland and Planck gray opacities, group mean opacities over selected energy ranges, the monochromatic absorption coefficients and the average ionization over a wide range of temperatures and densities. As described in this paper, these quantities are available for all of the elements presently on the data base and TOPS will provide the same quantities for any arbitrary mixture of these elements.

  19. Los Alamos PC estimating system

    SciTech Connect

    Stutz, R.A.; Lemon, G.D.

    1987-01-01

    The Los Alamos Cost Estimating System (QUEST) is being converted to run on IBM personal computers. This very extensive estimating system is capable of supporting cost estimators from many different and varied fields. QUEST does not dictate any fixed method for estimating. QUEST supports many styles and levels of detail estimating. QUEST can be used with or without data bases. This system allows the estimator to provide reports based on levels of detail defined by combining work breakdown structures. QUEST provides a set of tools for doing any type of estimate without forcing the estimator to use any given method. The level of detail in the estimate can be mixed based on the amount of information known about different parts of the project. The system can support many different data bases simultaneously. Estimators can modify any cost in any data base.

  20. Dynamic shock studies of vanadium

    SciTech Connect

    Chhabildas, L.C.; Hills, C.R.

    1985-01-01

    Using gas-gun loading techniques and velocity interferometric techniques, time-resolved wave profiles have been obtained in vanadium over the stress range of 2.9 to 9.7 GPa. The risetime data indicate steepened shock structures with increasing shock amplitude. However, unlike aluminum, finite risetimes are determined even at 9.7 GPa, indicating a large effective viscosity for the material. The dynamic yield strength measured at the Hugoniot elastic limit is 0.8 GPa and is approximately twice the static yield strength. Material softening is evidenced through measurements of shock velocity and yield strength determinations in the shocked state. The yield strength of the material upon release from the shocked state is estimated to be approx.0.43 GPa and is comparable to the static yield strength. Strain-rate dependent processes may be responsible for a higher elastic shear stress sustained before relaxation to an equilibrium value. The primary mode of deformation in shocked vanadium appears to be cross slip, resulting in dislocation tangles. Deformation twins are also observed in shock-recovered specimens with an increasing number with increased shock stress. The thermal diffusivity for vanadium is low, and the shear-strength loss observed in this material is consistent with the strength loss observed for other materials which also have low thermal diffusivities. It is conceivable that the loss of shear strength may be due to long thermal recovery times resulting from inhomogeneous deformation process.

  1. Molecular dynamics simulation of a piston driven shock wave in a hard sphere gas. Final Contractor ReportPh.D. Thesis

    NASA Technical Reports Server (NTRS)

    Woo, Myeung-Jouh; Greber, Isaac

    1995-01-01

    Molecular dynamics simulation is used to study the piston driven shock wave at Mach 1.5, 3, and 10. A shock tube, whose shape is a circular cylinder, is filled with hard sphere molecules having a Maxwellian thermal velocity distribution and zero mean velocity. The piston moves and a shock wave is generated. All collisions are specular, including those between the molecules and the computational boundaries, so that the shock development is entirely causal, with no imposed statistics. The structure of the generated shock is examined in detail, and the wave speed; profiles of density, velocity, and temperature; and shock thickness are determined. The results are compared with published results of other methods, especially the direct simulation Monte-Carlo method. Property profiles are similar to those generated by direct simulation Monte-Carlo method. The shock wave thicknesses are smaller than the direct simulation Monte-Carlo results, but larger than those of the other methods. Simulation of a shock wave, which is one-dimensional, is a severe test of the molecular dynamics method, which is always three-dimensional. A major challenge of the thesis is to examine the capability of the molecular dynamics methods by choosing a difficult task.

  2. Shock tubes and waves; Proceedings of the Thirteenth International Symposium, Niagara Falls, NY, July 6-9, 1981

    NASA Astrophysics Data System (ADS)

    Treanor, C. E.; Hall, J. G.

    1982-10-01

    The present conference on shock tubes and waves considers shock tube drivers, luminous shock tubes, shock tube temperature and pressure measurement, shock front distortion in real gases, nonlinear standing waves, transonic flow shock wave turbulent boundary interactions, wall roughness effects on reflected shock bifurcation, argon thermal conductivity, pattern generation in gaseous detonations, cylindrical resonators, shock tunnel-produced high gain lasers, fluid dynamic aspects of laser-metal interaction, and the ionization of argon gas behind reflected shock waves. Also discussed are the ionization relaxation of shock-heated plasmas and gases, discharge flow/shock tube studies of singlet oxygen, rotational and vibrational relaxation, chemiluminescence thermal and shock wave decomposition of hydrogen cyanide and hydrogen azide, shock wave structure in gas-particle mixtures at low Mach numbers, binary nucleation in a Ludwieg tube, shock liquefaction experiments, pipeline explosions, the shock wave ignition of pulverized coal, and shock-initiated methane combustion.

  3. Converging cylindrical shocks in ideal magnetohydrodynamics

    SciTech Connect

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-15

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The

  4. Converging cylindrical shocks in ideal magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.

    2014-09-01

    We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=sqrt{μ _0/p_0} I/(2 π ) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field

  5. [Obstructive shock].

    PubMed

    Pich, H; Heller, A R

    2015-05-01

    An acute obstruction of blood flow in central vessels of the systemic or pulmonary circulation causes the clinical symptoms of shock accompanied by disturbances of consciousness, centralization, oliguria, hypotension and tachycardia. In the case of an acute pulmonary embolism an intravascular occlusion results in an acute increase of the right ventricular afterload. In the case of a tension pneumothorax, an obstruction of the blood vessels supplying the heart is caused by an increase in extravascular pressure. From a hemodynamic viewpoint circulatory shock caused by obstruction is closely followed by cardiac deterioration; however, etiological and therapeutic options necessitate demarcation of cardiac from non-cardiac obstructive causes. The high dynamics of this potentially life-threatening condition is a hallmark of all types of obstructive shock. This requires an expeditious and purposeful diagnosis and a rapid and well-aimed therapy. PMID:25994928

  6. Shock-implanted noble gases. II - Additional experimental studies and recognition in naturally shocked terrestrial materials

    NASA Technical Reports Server (NTRS)

    Bogard, Donald; Horz, Friedrich; Johnson, Pratt

    1989-01-01

    The process by which ambient gases can be implanted into silicates by shocks was investigated by analyzing the noble-gas content of several experimentally and naturally shocked silicate samples. The retentivity of shock-implanted gas during stepwise heating in the laboratory was defined in terms of two parameters, namely, the activation energy for diffusion and the extraction temperature at which 50 percent of the gas is released, both of which correlate with the shock pressure. The experiments indicate that, with increasing shock pressure, gas implantation occurs through an increasing production of microcracks/defects in the silicate lattice. The degree of annealing of these defects control the degree of diffusive loss of implanted gas.

  7. Noble gas studies in vapor-growth diamonds: Comparison with shock-produced diamonds and the origin of diamonds in ureilites

    SciTech Connect

    Matsuda, Junichi; Fukunaga, Kazuya; Ito, Keisuke )

    1991-07-01

    The authors synthesized vapor-trowth diamonds by two kinds of Chemical Vapor Deposition (CVD) using microwave (MWCVD) and hot filament (HFCVD) ionization of gases, and examined elemental abundances and isotopic compositions of the noble gases trapped in the diamonds. It is remarkable that strong differences existed in the noble gas concentrations in the two kinds of CVD diamonds: large amounts of noble gases were trapped in the MWCVD diamonds, but not in the HFCVD diamonds. The heavy noble gases (Ar to Xe) in the MWCVD diamonds were highly fractionated compared with those in the ambient atmosphere, and are in good agreement with the calculated fractionation patterns for plasma at an electron temperature of 7,000-9,000 K. These results strongly suggest that the trapping mechanism of noble gases in CVD diamonds is ion implantation during diamond growth. The degrees of fractionation of heavy noble gases were also in good agreement with those in ureilites. The vapor-growth hypothesis is discussed in comparison with the impact-shock hypothesis as a better model for the origin of diamonds in ureilites. The diamond (and graphite, amorphous carbon, too) may have been deposited on early condensates such as Re, Ir, W, etc. This model explains the chemical features of vein material in ureilites; the refractory siderophile elements are enriched in carbon and noble gases and low in normal siderophiles. The vapor-growth model is also compatible with the oxygen isotopic data of ureilites which suggests that nebular processes are primarily responsible for the composition of ureilites.

  8. Sunset at the ALaMO

    NASA Video Gallery

    A new color all-sky camera has opened its eyes at the ALaMO, or Automated Lunar and Meteor Observatory, at NASA's Marshall Space Flight Center in Huntsville, Ala. Watch its inaugural video below, s...

  9. Publications of Los Alamos research 1988

    SciTech Connect

    Varjabedian, K.; Dussart, S.A.; McClary, W.J.; Rich, J.A.

    1989-12-01

    This bibliography lists unclassified publications of work done at the Los Alamos National Laboratory for 1988. The entries, which are subdivided by broad subject categories, are cross-referenced with an author index and a numeric index.

  10. New Rad Lab for Los Alamos

    SciTech Connect

    2008-08-06

    The topping out ceremony for a key construction stage in the Los Alamos National Laboratory's newest facility, the Radiological Laboratory Utility & Office Building. This is part of the National Nu...  

  11. Environmental surveillance at Los Alamos during 1994

    SciTech Connect

    1996-07-01

    This report describes environmental monitoring activities at Los Alamos National Laboratory for 1994. Data were collected to assess external penetrating radiation, airborne emissions, liquid effluents, radioactivity of environmental materials and food stuffs, and environmental compliance.

  12. New Rad Lab for Los Alamos

    ScienceCinema

    None

    2016-07-12

    The topping out ceremony for a key construction stage in the Los Alamos National Laboratory's newest facility, the Radiological Laboratory Utility & Office Building. This is part of the National Nu...  

  13. Shock wave control using liquid curtains

    NASA Astrophysics Data System (ADS)

    Colvert, Brendan; Tao, Xingtian; Eliasson, Veronica

    2014-11-01

    The effectiveness of a planar wall of liquid as a blast mitigation device is examined using a shock tube and a custom-designed and -built shock test chamber. Experimental data collection methods being used include high-speed schlieren photography and high-frequency pressure sensors. During the relevant shock interaction time periods, the liquid-gas interface is examined to determine its effect on shock waves. The characteristic quantities that reflect these effects include reflected-to-incident shock strength ratio, transmitted-to-incident shock strength ratio, transmitted and reflected impulse, and peak pressure reduction. These parameters are examined for correlations to incident wave speed, liquid mass, liquid density, and liquid viscosity. Initial results have been obtained that show a correlation between fluid mass and peak pressure reduction. More experiments are being performed to further explore this relationship as well as examine the effects of altering the other parameters such as liquid-gas interface geometry and using dilatant fluids.

  14. Edward Teller Returns to LOS Alamos

    NASA Astrophysics Data System (ADS)

    Hecker, Siegfried S.

    2010-01-01

    I was asked to share some reflections of Edward Teller's return to Los Alamos during my directorship. I met Teller late in his life. My comments focus on that time and they will be mostly in the form of stories of my interactions and those of my colleagues with Teller. Although the focus of this symposium is on Teller's contributions to science, at Los Alamos it was never possible to separate Teller's science from policy and controversy ...

  15. Los Alamos Space Weather Summer School

    NASA Astrophysics Data System (ADS)

    Koller, J.

    2011-12-01

    Los Alamos National Lab recently initiated a new summer school specializing on space science, space weather, and instrumentation. The school is geared towards graduate level students and has been established to bring graduate students together with internationally recognized scientists at the Los Alamos National Lab. Students are receiving a prestigious Vela Fellowship to cover relocation expenses and cost of living for the duration of their stay in Los Alamos. For two months students have the opportunity to attend science lectures given by distinguished researchers at LANL. Topics are related to space weather research including plasma physics, radiation belts, numerical modeling, solar wind physics, spacecraft charging, and instrumentation. Students are also working closely with a Los Alamos mentor on exciting space weather science topics with access to Los Alamos GPS and geosynchronous data. The summer school concludes with project presentations by the students in a technical forum. The program is designed for graduate students currently enrolled at US Universities and open to all nationalities. We are presenting an overview of this exciting new program funded by IGPP (Institute of Geophysics and Planetary Physics), the Global Security Directorate, and the Directorate for Science, Technology and Engineering at Los Alamos National Lab.

  16. Instabilities and Structure Evolution in Radiative Shocks

    NASA Astrophysics Data System (ADS)

    Doss, F. W.; Drake, R. P.; Visco, A. J.; Kuranz, C. C.; Grosskopf, M. J.; Reighard, A. B.; Knauer, J.

    2007-11-01

    Radiative shocks, systems in which radiation transport across the shock front contributes substantially to the properties and dynamics of the shock, occur frequently in astrophysical systems, motivating our high-energy-density experiments. Recent laser-driven experiments have produced collapsed shocks by launching 10-20 μm drive disks of Be into shock tubes of Xe gas at atmospheric pressure. This method produces strongly radiative shocks at well over 100 km/sec. Experiments using x-ray pinhole radiography of collapsed radiative shocks have revealed evidence of structure evolution, perhaps through instability mechanisms. Recent experiments provided simultaneous normal and oblique data. Theoretical work related to structure growth will also be reported. This research was sponsored by the NNSA through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA0064, and the NNSA Stewardship Science Graduate Fellowship.

  17. Cardiogenic Shock.

    PubMed

    Moskovitz, Joshua B; Levy, Zachary D; Slesinger, Todd L

    2015-08-01

    Cardiogenic shock is the leading cause of morbidity and mortality in patients presenting with acute coronary syndrome. Although early reperfusion strategies are essential to the management of these critically ill patients, additional treatment plans are often needed to stabilize and treat the patient before reperfusion may be possible. This article discusses pharmacologic and surgical interventions, their indications and contraindications, management strategies, and treatment algorithms.

  18. CULTURE SHOCK.

    ERIC Educational Resources Information Center

    WEINSTEIN, GERALD; AND OTHERS

    IN A PANEL, GEORGE BRAGLE AND NATHAN GOULD STRESS TEACHER PREPARATION TO COPE WITH THE THREATENING IMPACT OF CULTURE OR REALITY SHOCK. THEY RECOMMEND MODIFYING THE ATTITUDES OF TEACHERS BY ALTERING THEIR PERCEPTIONS, PROVIDING THEM WITH DIRECT EXPERIENCE WITH THE SOCIOCULTURAL MILIEU OF GHETTO SCHOOLS, AND REQUIRING THEM TO TAKE COURSES IN THE…

  19. Los Alamos Laser Eye Investigation.

    SciTech Connect

    Odom, C. R.

    2005-01-01

    A student working in a laser laboratory at Los Alamos National Laboratory sustained a serious retinal injury to her left eye when she attempted to view suspended particles in a partially evacuated target chamber. The principle investigator was using the white light from the flash lamp of a Class 4 Nd:YAG laser to illuminate the particles. Since the Q-switch was thought to be disabled at the time of the accident, the principal investigator assumed it would be safe to view the particles without wearing laser eye protection. The Laboratory Director appointed a team to investigate the accident and to report back to him the events and conditions leading up to the accident, equipment malfunctions, safety management causal factors, supervisory and management action/inaction, adequacy of institutional processes and procedures, emergency and notification response, effectiveness of corrective actions and lessons learned from previous similar events, and recommendations for human and institutional safety improvements. The team interviewed personnel, reviewed documents, and characterized systems and conditions in the laser laboratory during an intense six week investigation. The team determined that the direct and primary failures leading to this accident were, respectively, the principle investigator's unsafe work practices and the institution's inadequate monitoring of worker performance. This paper describes the details of the investigation, the human and institutional failures, and the recommendations for improving the laser safety program.

  20. Chondrule destruction in nebular shocks

    SciTech Connect

    Jacquet, Emmanuel; Thompson, Christopher

    2014-12-10

    Chondrules are millimeter-sized silicate spherules ubiquitous in primitive meteorites, but whose origin remains mysterious. One of the main proposed mechanisms for producing them is melting of solids in shock waves in the gaseous protoplanetary disk. However, evidence is mounting that chondrule-forming regions were enriched in solids well above solar abundances. Given the high velocities involved in shock models, destructive collisions would be expected between differently sized grains after passage of the shock front as a result of differential drag. We investigate the probability and outcome of collisions of particles behind a one-dimensional shock using analytic methods as well as a full integration of the coupled mass, momentum, energy, and radiation equations. Destruction of protochondrules seems unavoidable for solid/gas ratios ε ≳ 0.1, and possibly even for solar abundances because of 'sandblasting' by finer dust. A flow with ε ≳ 10 requires much smaller shock velocities (∼2 versus 8 km s{sup –1}) in order to achieve chondrule-melting temperatures, and radiation trapping allows slow cooling of the shocked fragments. Initial destruction would still be extensive; although re-assembly of millimeter-sized particles would naturally occur by grain sticking afterward, the compositional heterogeneity of chondrules may be difficult to reproduce. We finally note that solids passing through small-scale bow shocks around few kilometer-sized planetesimals might experience partial melting and yet escape fragmentation.

  1. Dehydration kinetics of shocked serpentine

    NASA Technical Reports Server (NTRS)

    Tyburczy, James A.; Ahrens, Thomas J.

    1988-01-01

    Experimental rates of dehydration of shocked and unshocked serpentine were determined using a differential scanning calorimetric technique. Dehydration rates in shocked serpentine are enhanced by orders of magnitude over corresponding rates in unshocked material, even though the impact experiments were carried out under conditions that inhibited direct impact-induced devolatilization. Extrapolation to temperatures of the Martian surface indicates that dehydration of shocked material would occur 20 to 30 orders of magnitude more rapidly than for unshocked serpentine. The results indicate that impacted planetary surfaces and associated atmospheres would reach chemical equilibrium much more quickly than calculations based on unshocked material would indicate, even during the earliest, coldest stages of accretion. Furthermore, it is suggested that chemical weathering of shocked planetary surfaces by solid-gas reactions would be sufficiently rapid that true equilibrium mineral assemblages should form.

  2. HERSCHEL FAR-INFRARED SPECTRAL-MAPPING OF ORION BN/KL OUTFLOWS: SPATIAL DISTRIBUTION OF EXCITED CO, H{sub 2}O, OH, O, AND C{sup +} IN SHOCKED GAS

    SciTech Connect

    Goicoechea, Javier R.; Cernicharo, José; Cuadrado, Sara; Etxaluze, Mireya; Chavarría, Luis; Neufeld, David A.; Vavrek, Roland; Encrenaz, Pierre; Melnick, Gary J.; Polehampton, Edward

    2015-01-20

    We present ∼2' × 2' spectral-maps of Orion Becklin-Neugebauer/Kleinmann-Low (BN/KL) outflows taken with Herschel at ∼12'' resolution. For the first time in the far-IR domain, we spatially resolve the emission associated with the bright H{sub 2} shocked regions ''Peak 1'' and ''Peak 2'' from that of the hot core and ambient cloud. We analyze the ∼54-310 μm spectra taken with the PACS and SPIRE spectrometers. More than 100 lines are detected, most of them rotationally excited lines of {sup 12}CO (up to J = 48-47), H{sub 2}O, OH, {sup 13}CO, and HCN. Peaks 1/2 are characterized by a very high L(CO)/L {sub FIR} ≈ 5 × 10{sup –3} ratio and a plethora of far-IR H{sub 2}O emission lines. The high-J CO and OH lines are a factor of ≈2 brighter toward Peak 1 whereas several excited H{sub 2}O lines are ≲50% brighter toward Peak 2. Most of the CO column density arises from T {sub k} ∼ 200-500 K gas that we associate with low-velocity shocks that fail to sputter grain ice mantles and show a maximum gas-phase H{sub 2}O/CO ≲ 10{sup –2} abundance ratio. In addition, the very excited CO (J > 35) and H{sub 2}O lines reveal a hotter gas component (T {sub k} ∼ 2500 K) from faster (v {sub S} > 25 km s{sup –1}) shocks that are able to sputter the frozen-out H{sub 2}O and lead to high H{sub 2}O/CO ≳ 1 abundance ratios. The H{sub 2}O and OH luminosities cannot be reproduced by shock models that assume high (undepleted) abundances of atomic oxygen in the preshock gas and/or neglect the presence of UV radiation in the postshock gas. Although massive outflows are a common feature in other massive star-forming cores, Orion BN/KL seems more peculiar because of its higher molecular luminosities and strong outflows caused by a recent explosive event.

  3. Joint Actinide Shock Physics Experimental Research - JASPER

    ScienceCinema

    None

    2016-07-12

    Commonly known as JASPER the Joint Actinide Shock Physics Experimental Research facility is a two stage light gas gun used to study the behavior of plutonium and other materials under high pressures, temperatures, and strain rates.

  4. Joint Actinide Shock Physics Experimental Research - JASPER

    SciTech Connect

    2014-10-31

    Commonly known as JASPER the Joint Actinide Shock Physics Experimental Research facility is a two stage light gas gun used to study the behavior of plutonium and other materials under high pressures, temperatures, and strain rates.

  5. Shock finding on a moving-mesh - II. Hydrodynamic shocks in the Illustris universe

    NASA Astrophysics Data System (ADS)

    Schaal, Kevin; Springel, Volker; Pakmor, Rüdiger; Pfrommer, Christoph; Nelson, Dylan; Vogelsberger, Mark; Genel, Shy; Pillepich, Annalisa; Sijacki, Debora; Hernquist, Lars

    2016-10-01

    Hydrodynamical shocks are a manifestation of the non-linearity of the Euler equations and play a fundamental role in cosmological gas dynamics. In this work, we identify and analyse shocks in the Illustris simulation, and contrast the results with those of non-radiative runs. We show that simulations with more comprehensive physical models of galaxy formation pose new challenges for shock finding algorithms due to radiative cooling and star-forming processes, prompting us to develop a number of methodology improvements. We find in Illustris a total shock surface area which is about 1.4 times larger at the present epoch compared to non-radiative runs, and an energy dissipation rate at shocks which is higher by a factor of around 7. Remarkably, shocks with Mach numbers above and below mathcal {M}≈ 10 contribute about equally to the total dissipation across cosmic time. This is in sharp contrast to non-radiative simulations, and we demonstrate that a large part of the difference arises due to strong black hole radio-mode feedback in Illustris. We also provide an overview of the large diversity of shock morphologies, which includes complex networks of halo-internal shocks, shocks on to cosmic sheets, feedback shocks due to black holes and galactic winds, as well as ubiquitous accretion shocks. In high-redshift systems more massive than 1012 M⊙, we discover the existence of a double accretion shock pattern in haloes. They are created when gas streams along filaments without being shocked at the outer accretion shock, but then forms a second, roughly spherical accretion shock further inside.

  6. Observation of laser driven supercritical radiative shock precursors.

    PubMed

    Bouquet, S; Stéhlé, C; Koenig, M; Chièze, J-P; Benuzzi-Mounaix, A; Batani, D; Leygnac, S; Fleury, X; Merdji, H; Michaut, C; Thais, F; Grandjouan, N; Hall, T; Henry, E; Malka, V; Lafon, J-P J

    2004-06-01

    We present a supercritical radiative shock experiment performed with the LULI nanosecond laser facility. Using targets filled with xenon gas at low pressure, the propagation of a strong shock with a radiative precursor is evidenced. The main measured shock quantities (electronic density and propagation velocity) are shown to be in good agreement with theory and numerical simulations. PMID:15245230

  7. Shocks in supersonic sand.

    PubMed

    Rericha, Erin C; Bizon, Chris; Shattuck, Mark D; Swinney, Harry L

    2002-01-01

    We measure time-averaged velocity, density, and temperature fields for steady granular flow past a wedge. We find the flow to be supersonic with a speed of granular pressure disturbances (sound speed) equal to about 10% of the flow speed, and we observe shocks nearly identical to those in a supersonic gas. Molecular dynamics simulations of Newton's laws yield fields in quantitative agreement with experiment. A numerical solution of Navier-Stokes-like equations agrees with a molecular dynamics simulation for experimental conditions excluding wall friction.

  8. Status of Monte Carlo at Los Alamos

    SciTech Connect

    Thompson, W.L.; Cashwell, E.D.

    1980-01-01

    At Los Alamos the early work of Fermi, von Neumann, and Ulam has been developed and supplemented by many followers, notably Cashwell and Everett, and the main product today is the continuous-energy, general-purpose, generalized-geometry, time-dependent, coupled neutron-photon transport code called MCNP. The Los Alamos Monte Carlo research and development effort is concentrated in Group X-6. MCNP treats an arbitrary three-dimensional configuration of arbitrary materials in geometric cells bounded by first- and second-degree surfaces and some fourth-degree surfaces (elliptical tori). Monte Carlo has evolved into perhaps the main method for radiation transport calculations at Los Alamos. MCNP is used in every technical division at the Laboratory by over 130 users about 600 times a month accounting for nearly 200 hours of CDC-7600 time.

  9. New Generation of Los Alamos Opacity Tables

    NASA Astrophysics Data System (ADS)

    Colgan, James; Kilcrease, D. P.; Magee, N. H.; Sherrill, M. E.; Abdallah, J.; Hakel, P.; Fontes, C. J.; Guzik, J. A.; Mussack, K. A.

    2016-05-01

    We present a new generation of Los Alamos OPLIB opacity tables that have been computed using the ATOMIC code. Our tables have been calculated for all 30 elements from hydrogen through zinc and are publicly available through our website. In this poster we discuss the details of the calculations that underpin the new opacity tables. We also show several recent applications of the use of our opacity tables to solar modeling and other astrophysical applications. In particular, we demonstrate that use of the new opacities improves the agreement between solar models and helioseismology, but does not fully resolve the long-standing `solar abundance' problem. The Los Alamos National Laboratory is operated by Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under Contract No. DE-AC5206NA25396.

  10. Publications of Los Alamos Research, 1983

    SciTech Connect

    Sheridan, C.J.; McClary, W.J.; Rich, J.A.; Rodriguez, L.L.

    1984-10-01

    This bibliography is a compilation of unclassified publications of work done at the Los Alamos National Laboratory for 1983. Papers published in 1982 are included regardless of when they were actually written. Publications received too late for inclusion in earlier compilations have also been listed. Declassification of previously classified reports is considered to constitute publication. All classified issuances are omitted - even those papers, themselves unclassified, which were published only as part of a classified document. If a paper was published more than once, all places of publication are included. The bibliography includes Los Alamos National Laboratory reports, papers released as non-Laboratory reports, journal articles, books, chapters of books, conference papers either published separately or as part of conference proceedings issued as books or reports, papers publishd in congressional hearings, theses, and US patents. Publications by Los Alamos authors that are not records of Laboratory-sponsored work are included when the Library becomes aware of them.

  11. Publications of Los Alamos research 1980

    SciTech Connect

    Salazar, C.A.; Willis, J.K.

    1981-09-01

    This bibliography is a compilation of unclassified publications of work done at the Los Alamos National Laboratory for 1980. Papers published in 1980 are included regardless of when they were actually written. Publications received too late for inclusion in earlier compilations have also been listed. Declassification of previously classified reports is considered to constitute publication. All classified issuances are omitted-even those papers, themselves unclassified, which were published only as part of a classified document. If a paper was pubished more than once, all places of publication are included. The bibliography includes Los Alamos National Laboratory reports, papers released as non-laboratory reports, journal articles, books, chapters of books, conference papers published either separately or as part of conference proceedings issued as books or reports, papers published in congressional hearings, theses, and US patents. Publications by Los Alamos authors that are not records of Laboratory-sponsored work are included when the Library becomes aware of them.

  12. Simulations of Turbulent Flows with Strong Shocks and Density Variations

    SciTech Connect

    Zhong, Xiaolin

    2012-12-13

    In this report, we present the research efforts made by our group at UCLA in the SciDAC project Simulations of turbulent flows with strong shocks and density variations. We use shock-fitting methodologies as an alternative to shock-capturing schemes for the problems where a well defined shock is present. In past five years, we have focused on development of high-order shock-fitting Navier-Stokes solvers for perfect gas flow and thermochemical non-equilibrium flow and simulation of shock-turbulence interaction physics for very strong shocks. Such simulation has not been possible before because the limitation of conventional shock capturing methods. The limitation of shock Mach number is removed by using our high-order shock-fitting scheme. With the help of DOE and TeraGrid/XSEDE super computing resources, we have obtained new results which show new trends of turbulence statistics behind the shock which were not known before. Moreover, we are also developing tools to consider multi-species non-equilibrium flows. The main results are in three areas: (1) development of high-order shock-fitting scheme for perfect gas flow, (2) Direct Numerical Simulation (DNS) of interaction of realistic turbulence with moderate to very strong shocks using super computing resources, and (3) development and implementation of models for computation of mutli-species non-quilibrium flows with shock-fitting codes.

  13. [Definition of shock types].

    PubMed

    Adams, H A; Baumann, G; Gänsslen, A; Janssens, U; Knoefel, W; Koch, T; Marx, G; Müller-Werdan, U; Pape, H C; Prange, W; Roesner, D; Standl, T; Teske, W; Werner, G; Zander, R

    2001-11-01

    Definitions of shock types. Hypovolaemic shock is a state of insufficient perfusion of vital organs with consecutive imbalance of oxygen supply and demand due to an intravascular volume deficiency with critically impaired cardiac preload. Subtypes are haemorrhagic shock, hypovolaemic shock in the narrow sense, traumatic-haemorrhagic shock and traumatic-hypovolaemic shock. Cardiac shock is caused by a primary critical cardiac pump failure with consecutive inadequate oxygen supply of the organism. Anaphylactic shock is an acute failure of blood volume distribution (distributive shock) and caused by IgE-dependent, type-I-allergic, classical hypersensibility, or a physically, chemically, or osmotically induced IgE-independent anaphylactoid hypersensibility. The septic shock is a sepsis-induced distribution failure of the circulating blood volume in the sense of a distributive shock. The neurogenic shock is a distributive shock induced by generalized and extensive vasodilatation with consecutive hypovolaemia due to an imbalance of sympathetic and parasympathetic regulation of vascular smooth muscles. PMID:11753724

  14. Preliminary results investigating mix in colliding-shock experiments

    NASA Astrophysics Data System (ADS)

    Offermann, Dustin; Keiter, Paul; Loomis, Eric; Welser-Sherrill, Leslie; Fincke, Jim; Lanier, Nick

    2011-10-01

    Experiments have been performed at the Omega laser facility to investigate turbulence-driven mix from two colliding shocks, such as expected in ICF ignition capsules. Two shocks were generated at either end of a cylindrical, CH foam. The evolution of an Al tracer layer at one end of the foam was measured using point-projection radiography. Comparison of this data with simulations from the code, RAGE has been done to improve its predictive capability for ICF experiments. RAGE implements the Besnard-Harlow-Rauenzahn (BHR) model, which is intended for turbulent transport in fluids with large density variations. Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by the Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396.

  15. Radiative shock calculations in various media

    NASA Astrophysics Data System (ADS)

    Michaut, C.; Boireau, L.; Leygnac, S.; Cornille, M.; Stehle, C.

    2002-06-01

    We are modeling shocks with structures governed by their radiative precursor. At this point, we are assuming a geometrically-plan shock in an ionized gas, which behaves differently than in a perfect gas. The ionization structure and the excitation energy are calculated from the local temperatures and densities, using hydrogen-like model atoms. This approach can thus be applied to heavy elements like Xenon, which is used in the experiment of astrophysical radiative shocks with the laser of the LULI, at the Ecole Polytechnique (France). After studying in details the shocks in Xenon, we now calculate the atomic data for multiple chemical elements as Hydrogen, Helium, Carbon which are everywhere in astrophysical objects, and as Argon, Krypton which are monoatomic gases. We thus investigate the jump conditions in different media and we will try to propose a phenomenological description of the radiative shocks in the stellar objects and their envelopes.

  16. On the effect of conductivity of a shock-compressed gas on interferometric recording of parameters of motion of a liner

    SciTech Connect

    Ogorodnikov, V. A. Mikhailov, A. L.; Peshkov, V. V.; Bogdanov, E. N.; Rodionov, A. V.; Sedov, A. A.; Fedorov, A. V.; Nazarov, D. V.; Finyushin, S. A.; Dudoladov, V. I.; Erunov, S. V.; Blikov, A. O.

    2012-01-15

    We report on the results of a study of the acceleration dynamics of an aluminum liner to a velocity of 5.5 km/s using continuous recording of velocity (velocity interferometer system for any reflector (VISAR) and Fabry-Perot interferometer) and motion trajectory (radiointerferometer and resistive transducer) in air and in a helium atmosphere. It is found that for liner velocities exceeding 4.0 and 5.0 km/s, the displacement of the shock wave front is recorded by the radiointerferometer in air and helium, respectively. At these velocities, the conductivities of air and helium behind the shock wave front are estimated.

  17. Curved shock theory

    NASA Astrophysics Data System (ADS)

    Mölder, S.

    2016-07-01

    Curved shock theory (CST) is introduced, developed and applied to relate pressure gradients, streamline curvatures, vorticity and shock curvatures in flows with planar or axial symmetry. Explicit expressions are given, in an influence coefficient format, that relate post-shock pressure gradient, streamline curvature and vorticity to pre-shock gradients and shock curvature in steady flow. The effect of pre-shock flow divergence/convergence, on vorticity generation, is related to the transverse shock curvature. A novel derivation for the post-shock vorticity is presented that includes the effects of pre-shock flow non-uniformities. CST applicability to unsteady flows is discussed.

  18. Localized shocks

    NASA Astrophysics Data System (ADS)

    Roberts, Daniel A.; Stanford, Douglas; Susskind, Leonard

    2015-03-01

    We study products of precursors of spatially local operators, , where W x ( t) = e - iHt W x e iHt . Using chaotic spin-chain numerics and gauge/gravity duality, we show that a single precursor fills a spatial region that grows linearly in t. In a lattice system, products of such operators can be represented using tensor networks. In gauge/gravity duality, they are related to Einstein-Rosen bridges supported by localized shock waves. We find a geometrical correspondence between these two descriptions, generalizing earlier work in the spatially homogeneous case.

  19. SEDs at Los Alamos: A Personal Memoir

    NASA Astrophysics Data System (ADS)

    Bederson, Benjamin

    2001-03-01

    I have written this personal memoir approximately 55 years after the events I describe. It is based almost exclusively on memory, since apart from the diary I kept while on Tinian, I have few documents concerning it. It covers my service in the U.S. Army's Special Engineering Detachment (SED) in Oak Ridge and Los Alamos in 1944-45, on Tinian island, the launching pad for the bombing raids on Japan, in the summer and fall of 1945, and my return to Los Alamos until my discharge in January 1946.

  20. Grain destruction in a supernova remnant shock wave

    SciTech Connect

    Raymond, John C.; Gaetz, Terrance J.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Sankrit, Ravi

    2013-12-01

    Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants (SNRs), gradually enriching the gas phase with refractory elements. We have measured emission in C IV λ1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 μm and the X-ray intensity profiles. Thus, these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the C IV intensity 10'' behind the shock is too high compared with the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction, and the dust properties over parsec scales in the pre-shock medium limit our ability to test dust destruction models in detail.

  1. Grain Destruction in a Supernova Remnant Shock Wave

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi

    2014-01-01

    Dust grains are sputtered away in the hot gas behind shock fronts in supernova remnants, gradually enriching the gas phase with refractory elements. We have measured emission in C IV (lambda)1550 from C atoms sputtered from dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop. Overall, the intensity observed behind the shock agrees approximately with predictions from model calculations that match the Spitzer 24 micron and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10'' behind the shock is too high compared to the intensities at the shock and 25'' behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre- shock medium limit our ability to test dust destruction models in detail.

  2. Shock Prevention

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The electrician pictured is installing a General Electric Ground Fault Interrupter (GFI), a device which provides protection against electrical shock in the home or in industrial facilities. Shocks due to defective wiring in home appliances or other electrical equipment can cause severe burns, even death. As a result, the National Electrical Code now requires GFIs in all new homes constructed. This particular type of GFI employs a sensing element which derives from technology acquired in space projects by SCI Systems, Inc., Huntsville, Alabama, producer of sensors for GE and other manufacturers of GFI equipment. The sensor is based on the company's experience in developing miniaturized circuitry for space telemetry and other spacecraft electrical systems; this experience enabled SCI to package interruptor circuitry in the extremely limited space available and to produce sensory devices at practicable cost. The tiny sensor measures the strength of the electrical current and detects current differentials that indicate a fault in the functioning of an electrical system. The sensing element then triggers a signal to a disconnect mechanism in the GFI, which cuts off the current in the faulty circuit.

  3. Converging finite-strength shocks

    NASA Astrophysics Data System (ADS)

    Axford, R. A.; Holm, D. D.

    1981-01-01

    The converging shock problem was first solved by Guderley and later by Landau and Stanyukovich for infinitely strong shocks in an ideal gas with spherical and cylindrical symmetry. This problem is solved herein for finite-strength shocks and a non-ideal-gas equation of state with an adiabatic bulk modulus of the type Bs= {- v∂ p}/{∂ v| s} = ( p +B) f( v) , where B is a constant with the dimensions of pressure, and f(v) is an arbitrary function of the specific volume. Self-similar profiles of the particle velocity and thermodynamic variables are studied explicitly for two cases with constant specific heat at constant volume; the Tait-Kirkwood-Murnaghan equation, f(v) = constant, and the Walsh equation, f(v) = v/A, where A = constant. The first case reduces to the ideal gas when B = 0. In both cases the flow behind the shock front exhibits an unbalanced buoyant force instability at a critical Mach number which depends upon equation-of-state parameters.

  4. Corotating shock structures

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.

    1972-01-01

    Consideration of observed interplanetary shocks leads to the conclusion that a corotating forward shock has not been unambiguously identified at 1 AU. A reverse shock identified in September 1967 is a likely candidate for a corotating structure.

  5. What Is Cardiogenic Shock?

    MedlinePlus

    ... page from the NHLBI on Twitter. What Is Cardiogenic Shock? Cardiogenic (kar-dee-oh-JE-nik) shock is ... treated right away. The most common cause of cardiogenic shock is damage to the heart muscle from a ...

  6. Induction inserts at the Los Alamos PSR

    SciTech Connect

    King-Yuen Ng

    2002-09-30

    Ferrite-loaded induction tuners installed in the Los Alamos Proton Storage Ring have been successful in compensating space-charge effects. However, the resistive part of the ferrite introduces unacceptable microwave instability and severe bunch lengthening. An effective cure was found by heating the ferrite cores up to {approx} 130 C. An understanding of the instability and cure is presented.

  7. Los Alamos waste drum shufflers users manual

    SciTech Connect

    Rinard, P.M.; Adams, E.L.; Painter, J.

    1993-08-24

    This user manual describes the Los Alamos waste drum shufflers. The primary purpose of the instruments is to assay the mass of {sup 235}U (or other fissile materials) in drums of assorted waste. It can perform passive assays for isotopes that spontaneously emit neutrons or active assays using the shuffler technique as described on this manual.

  8. Proceedings of the Los Alamos neutrino workshop

    SciTech Connect

    Boehm, F.; Stephenson, G.J. Jr.

    1982-08-01

    A workshop on neutrino physics was held at Los Alamos from June 8 to 12, 1981. The material presented has been provided in part by the organizers, in part by the chairmen of the working sessions. Closing date for contributions was October 1981.

  9. Los Alamos Fires From Landsat 7

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On May 9, 2000, the Landsat 7 satellite acquired an image of the area around Los Alamos, New Mexico. The Landsat 7 satellite acquired this image from 427 miles in space through its sensor called the Enhanced Thematic Mapper Plus (ETM+). Evident within the imagery is a view of the ongoing Cerro Grande fire near the town of Los Alamos and the Los Alamos National Laboratory. Combining the high-resolution (30 meters per pixel in this scene) imaging capacity of ETM+ with its multi-spectral capabilities allows scientists to penetrate the smoke plume and see the structure of the fire on the surface. Notice the high-level of detail in the infrared image (bottom), in which burn scars are clearly distinguished from the hotter smoldering and flaming parts of the fire. Within this image pair several features are clearly visible, including the Cerro Grande fire and smoke plume, the town of Los Alamos, the Los Alamos National Laboratory and associated property, and Cerro Grande peak. Combining ETM+ channels 7, 4, and 2 (one visible and two infrared channels) results in a false color image where vegetation appears as bright to dark green (bottom image). Forested areas are generally dark green while herbaceous vegetation is light green. Rangeland or more open areas appear pink to light purple. Areas with extensive pavement or urban development appear light blue or white to purple. Less densely-developed residential areas appear light green and golf courses are very bright green. The areas recently burned appear black. Dark red to bright red patches, or linear features within the burned area, are the hottest and possibly actively burning areas of the fire. The fire is spreading downslope and the front of the fire is readily detectable about 2 kilometers to the west and south of Los Alamos. Combining ETM+ channels 3, 2, and 1 provides a true-color image of the greater Los Alamos region (top image). Vegetation is generally dark to medium green. Forested areas are very dark green

  10. Los Alamos Explosives Performance Key to Stockpile Stewardship

    SciTech Connect

    Dattelbaum, Dana

    2014-11-03

    As the U.S. Nuclear Deterrent ages, one essential factor in making sure that the weapons will continue to perform as designed is understanding the fundamental properties of the high explosives that are part of a nuclear weapons system. As nuclear weapons go through life extension programs, some changes may be advantageous, particularly through the addition of what are known as "insensitive" high explosives that are much less likely to accidentally detonate than the already very safe "conventional" high explosives that are used in most weapons. At Los Alamos National Laboratory explosives research includes a wide variety of both large- and small-scale experiments that include small contained detonations, gas and powder gun firings, larger outdoor detonations, large-scale hydrodynamic tests, and at the Nevada Nuclear Security Site, underground sub-critical experiments.

  11. Los Alamos Explosives Performance Key to Stockpile Stewardship

    ScienceCinema

    Dattelbaum, Dana

    2016-07-12

    As the U.S. Nuclear Deterrent ages, one essential factor in making sure that the weapons will continue to perform as designed is understanding the fundamental properties of the high explosives that are part of a nuclear weapons system. As nuclear weapons go through life extension programs, some changes may be advantageous, particularly through the addition of what are known as "insensitive" high explosives that are much less likely to accidentally detonate than the already very safe "conventional" high explosives that are used in most weapons. At Los Alamos National Laboratory explosives research includes a wide variety of both large- and small-scale experiments that include small contained detonations, gas and powder gun firings, larger outdoor detonations, large-scale hydrodynamic tests, and at the Nevada Nuclear Security Site, underground sub-critical experiments.

  12. Decommissioning the UHTREX Reactor Facility at Los Alamos, New Mexico

    SciTech Connect

    Salazar, M.; Elder, J.

    1992-08-01

    The Ultra-High Temperature Reactor Experiment (UHTREX) facility was constructed in the late 1960s to advance high-temperature and gas-cooled reactor technology. The 3-MW reactor was graphite moderated and helium cooled and used 93% enriched uranium as its fuel. The reactor was run for approximately one year and was shut down in February 1970. The decommissioning of the facility involved removing the reactor and its associated components. This document details planning for the decommissioning operations which included characterizing the facility, estimating the costs of decommissioning, preparing environmental documentation, establishing a system to track costs and work progress, and preplanning to correct health and safety concerns in the facility. Work to decommission the facility began in 1988 and was completed in September 1990 at a cost of $2.9 million. The facility was released to Department of Energy for other uses in its Los Alamos program.

  13. Los Alamos National Laboratory TRU waste sampling projects

    SciTech Connect

    Yeamans, D.; Rogers, P.; Mroz, E.

    1997-02-01

    The Los Alamos National Laboratory (LANL) has begun characterizing transuranic (TRU) waste in order to comply with New Mexico regulations, and to prepare the waste for shipment and disposal at the Waste Isolation Pilot Plant (WIPP), near Carlsbad, New Mexico. Sampling consists of removing some head space gas from each drum, removing a core from a few drums of each homogeneous waste stream, and visually characterizing a few drums from each heterogeneous waste stream. The gases are analyzed by GC/MS, and the cores are analyzed for VOC`s and SVOC`s by GC/MS and for metals by AA or AE spectroscopy. The sampling and examination projects are conducted in accordance with the ``DOE TRU Waste Quality Assurance Program Plan`` (QAPP) and the ``LANL TRU Waste Quality Assurance Project Plan,`` (QAPjP), guaranteeing that the data meet the needs of both the Carlsbad Area Office (CAO) of DOE and the ``WIPP Waste Acceptance Criteria, Rev. 5,`` (WAC).

  14. Turbulent shock processing, relevant to shock-cloud interactions

    NASA Astrophysics Data System (ADS)

    Hansen, J. Freddy

    2008-04-01

    The evolution of interstellar clouds following the passage of a supernova shock is an important astrophysical phenomenon; the shock passage may trigger star formation and the post-shock flow surrounding the clouds will strip them of material, effectively limiting cloud life times. Experiments conducted at the Omega laser attempt to (a) quantify the mass-stripping of a single cloud, and (b) simulate the effects of nearby clouds interacting with each other. A strong shock is driven (using 5 kJ of the 30 kJ Omega laser) into a cylinder filled with low-density foam with embedded 120 μm Al spheres simulating interstellar clouds. The density ratio between Al and foam is ˜9. Material is continuously being stripped from a cloud at a rate which is inconsistent with laminar models for mass-stripping; the cloud is fully stripped by 80 ns-100 ns, ten times faster than the laminar model. A new model for turbulent mass-stripping is developed [1,2] that agrees with the observed rate and which should scale to astrophysical conditions. Two interacting spherical clouds are observed to turn their upstream sections to face each other, a result that is completely opposite of earlier work [3] on two interacting cylinders. The difference between these two cases is explained by the relative strength of shocks reflected from the clouds. [1] J.F. Hansen et al, ``Experiment on the Mass-Stripping of an Interstellar Cloud Following Shock Passage,'' Astrophys. J. 662, 379-388 (2007). [2] J.F. Hansen et al, ``Experiment on the mass-stripping of an interstellar cloud in a high Mach number post-shock flow,'' Phys. Plasmas 14, 056505 (2007). [3] C. Tomkins et al, ``A quantitative study of the interaction of two Richtmyer-Meshkov-unstable gas cylinders,'' Phys. Fluids. 15, 986 (2003).

  15. Shock Compression of Simulated Adobe

    NASA Astrophysics Data System (ADS)

    Braithwaite, C. H.; Church, P. D.; Gould, P. J.; Stewart, B.; Jardine, A. P.

    2015-06-01

    A series of plate impact experiments were conducted to investigate the shock response of a simulant for adobe, a traditional form of building material widely used around the world. Air dried bricks were sourced from the London brick company, dry machined and impacted at a range of velocities in a single stage gas gun. The shock Hugoniot was determined (Us = 2.26up + 0.33) as well as release information. The material was found to behave in a manner which was similar to that of loose sand and considerably less stiff than a weak porous sandstone. The effect of any cementing of the grains was examined by shocking powdered samples contained within a cell arrangement. The research was funded by DSTL through a WSTC contract.

  16. Effect of neo red cells on hemodynamics and blood gas transport in canine hemorrhagic shock and its safety for vital organs.

    PubMed

    Usuba, A; Motoki, R; Sakaguchi, K; Suzuki, K; Kamitani, T

    1994-01-01

    The purpose of this study was to evaluate the effects of liposome encapsulated hemoglobin named "Neo Red Cells (NRC)" on canine hemorrhagic shock model and its safety for the vital organs in a whole blood exchange model. HEMORRHAGIC SHOCK: Nine adult mongrel dogs were used. Under mechanical ventilation inhaling room air, blood was withdrawn via an artery at a rate of 40 ml/min in order to induce hemorrhagic shock (systolic pressure below 60 mm Hg) and then NRC was transfused. For each animal, three to five cycles of bloodletting and NRC transfusion were performed. After blood exchange, total peripheral resistance index (TPRI) decreased and cardiac index (CI) increased. These changes were more marked in the high exchange group (exchange rate over 88%; five animals) than in the low exchange group (less than 88%; four animals), indicating that the low viscosity NRC reduced the load on the circulatory system. The A-V difference in oxygen content per lg hemoglobin was greater after blood exchange, indicating that oxygen binding capacity of NRC is higher than that of red blood cells. WHOLE BLOOD EXCHANGE: Five beagles were used for the blood exchange. The blood was withdrawn from an artery at a rate of 15 ml/min and NRC was infused at the same time. A dog whose blood was exchanged with hydroxyethylstarch instead of NRC died within 15 hours after blood exchange. Three dogs whose blood was exchanged with NRC (exchange rate was from 82 to 90%) have been living over a year without any side effects. A dog sacrificed on the 15th postoperative day for autopsy, microscopically showed no side effects in vital organs. We conclude that NRC is more suitable than natural blood for treatment of hemorrhagic shock and safe for vital organs.

  17. Shock waves in the large scale structure of the universe

    NASA Astrophysics Data System (ADS)

    Ryu, Dongsu

    Cosmological shock waves result from the supersonic flow motions induced by hierarchical formation of nonlinear structures in the universe. Like most astrophysical shocks, they are collisionless shocks which form in the tenuous intergalactic plasma via collective electromagnetic interactions between particles and electromagnetic fields. The gravitational energy released during the structure formation is transferred by these shocks to the intergalactic gas in several different forms. In addition to the gas entropy, cosmic rays are produced via diffusive shock acceleration, magnetic fields are generated via the Biermann battery mechanism and Weibel instability as well as the Bell-Lucek mechanism, and vorticity is generated at curved shocks. Here we review the properties, roles, and consequences of the shock waves in the context of the large scale structure of the universe.

  18. Shock Waves in the Large Scale Structure of the Universe

    NASA Astrophysics Data System (ADS)

    Ryu, Dongsu

    2008-04-01

    Cosmological shock waves result from the supersonic flow motions induced by hierarchical formation of nonlinear structures in the universe. Like most astrophysical shocks, they are collisionless shocks which form in the tenuous intergalactic plasma via collective electromagnetic interactions between particles and electromagnetic fields. The gravitational energy released during the structure formation is transferred by these shocks to the intergalactic gas in several different forms: in addition to the gas entropy, cosmic rays are produced via diffusive shock acceleration, magnetic fields are generated via the Biermann battery mechanism and Weibel instability, and vorticity is generated at curved shocks. Here I review the properties, roles, and consequences of the shock waves in the context of the large scale structure of the universe.

  19. Analytical Treatment of Normal Condensation Shock

    NASA Technical Reports Server (NTRS)

    Heybey

    1947-01-01

    The condensation of water vapor in an air consequences: acquisition of heat (liberated heat vaporization; loss of mass on the part of the flowing gas (water vapor is converted to liquid); change in the specific gas constants and of the ratio k of the specific heats (caused by change of gas composition). A discontinuous change of state is therefore connected with the condensation; schlieren photographs of supersonic flows in two-dimensional Laval nozzles show two intersecting oblique shock fronts that in the case of high humidities may merge near the point of intersection into one normal shock front.

  20. EXPERIMENTAL STUDY OF SHOCK WAVE DYNAMICS IN MAGNETIZED PLASMAS

    SciTech Connect

    Nirmol K. Podder

    2009-03-17

    In this four-year project (including one-year extension), the project director and his research team built a shock-wave-plasma apparatus to study shock wave dynamics in glow discharge plasmas in nitrogen and argon at medium pressure (1–20 Torr), carried out various plasma and shock diagnostics and measurements that lead to increased understanding of the shock wave acceleration phenomena in plasmas. The measurements clearly show that in the steady-state dc glow discharge plasma, at fixed gas pressure the shock wave velocity increases, its amplitude decreases, and the shock wave disperses non-linearly as a function of the plasma current. In the pulsed discharge plasma, at fixed gas pressure the shock wave dispersion width and velocity increase as a function of the delay between the switch-on of the plasma and shock-launch. In the afterglow plasma, at fixed gas pressure the shock wave dispersion width and velocity decrease as a function of the delay between the plasma switch-off and shock-launch. These changes are found to be opposite and reversing towards the room temperature value which is the initial condition for plasma ignition case. The observed shock wave properties in both igniting and afterglow plasmas correlate well with the inferred temperature changes in the two plasmas.

  1. Pressure effects on the ejection of material from shocked tin surfaces

    SciTech Connect

    Zellner, M. B.; Hammerberg, J. E.; Hixson, R. S.; Morley, K. B.; Obst, A. W.; Olson, R. T.; Payton, J. R.; Rigg, P. A.; Buttler, W. T.; Grover, M.; Iverson, A. J.; Macrum, G. S.; Stevens, G. D.; Turley, W. D.; Veeser, L.; Routley, N.

    2007-12-12

    Los Alamos National Lab (LANL) is actively engaged in the development of a model to predict the formation of micron-scale fragments ejected (ejecta) from shocked metals that have surface defects. The LANL ejecta model considers that the amount of ejecta is mainly related to the material's phase on shock release at the free-surface. This effort investigates the relation between ejecta production and shock-breakout pressure for Sn shocked with high explosives to pressures near the solid-on-release/partial-liquid-on-release phase transition region. We found that the amount of ejecta produced for shock-breakout pressures that resulted in partial-liquid-on-release increased significantly compared to that which resulted in solid-on-release. Additionally, we found that the amount of ejecta remained relatively constant within the partial-liquid-on-release, regardless of shock-breakout pressure.

  2. Tritium monitor calibration at Los Alamos National Laboratory

    SciTech Connect

    Bjork, C.J.; Aikin, D.J.; Houlton, T.W.

    1997-08-01

    Tritium in air is monitored at Los Alamos National Laboratory (LANL) with air breathing instruments based on ionization chambers. Stack emissions are continuously monitored from sample tubes which each connect to a Tritium bubble which differentially collects HTO and HT. A set of glass vials of glycol capture the HTO. The HT is oxidized with a palladium catalyst and the resultant HTO is captured in a second set of vials of glycol. The glycol is counted with a liquid scintillation counter. All calibrations are performed with tritium containing gas. The Radiation Instrumentation and Calibration (RIC) Team has constructed and maintains two closed loop gas handling systems based on femto TECH model U24 tritium ion chamber monitors: a fixed system housed in a fume hood and a portable system mounted on two two wheeled hand trucks. The U24 monitors are calibrated against tritium in nitrogen gas standards. They are used as standard transfer instruments to calibrate other ion chamber monitors with tritium in nitrogen, diluted with air. The gas handling systems include a circulation pump which permits a closed circulation loop to be established among the U24 monitor and typically two to four other monitors of a given model during calibration. Fixed and portable monitors can be calibrated. The stack bubblers are calibrated in the field by: blending a known concentration of tritium in air within the known volume of the two portable carts, coupled into a common loop; releasing that gas mixture into a ventilation intake to the stack; collecting oxidized tritium in the bubbler; counting the glycol; and using the stack and bubbler flow rates, computing the bubbler`s efficiency. Gas calibration has become a convenient and quality tool in maintaining the tritium monitors at LANL.

  3. Particle Acceleration in Shock-Shock Interaction

    NASA Astrophysics Data System (ADS)

    Nakanotani, Masaru; Matsukiyo, Shuichi; Hada, Tohru

    2015-04-01

    Collisionless shock waves play a crucial role in producing high energy particles. One of the most plausible acceleration mechanisms is the first order Fermi acceleration in which non-thermal particles statistically gain energy while scattered by MHD turbulence both upstream and downstream of a shock. Indeed, X-ray emission from energetic particles accelerated at supernova remnant shocks is often observed [e.g., Uchiyama et al., 2007]. Most of the previous studies on shock acceleration assume the presence of a single shock. In space, however, two shocks frequently come close to or even collide with each other. For instance, it is observed that a CME (coronal mass ejection) driven shock collides with the earth's bow shock [Hietala et al., 2011], or interplanetary shocks pass through the heliospheric termination shock [Lu et al., 1999]. Colliding shocks are observed also in high power laser experiments [Morita et al., 2013]. It is expected that shock-shock interactions efficiently produce high energy particles. A previous work using hybrid simulation [Cargill et al., 1986] reports efficient ion acceleration when supercritical two shocks collide. In the hybrid simulation, however, the electron dynamics cannot be resolved so that electron acceleration cannot be discussed in principle. Here, we perform one-dimensional full Particle-in-Cell (PIC) simulations to examine colliding two symmetric oblique shocks and the associated electron acceleration. In particular, the following three points are discussed in detail. 1. Energetic electrons are observed upstream of the two shocks before their collision. These energetic electrons are efficiently accelerated through multiple reflections at the two shocks (Fermi acceleration). 2. The reflected electrons excite large amplitude upstream waves. Electron beam cyclotron instability [Hasegawa, 1975] and electron fire hose instability [Li et al., 2000] appear to occur. 3. The large amplitude waves can scatters energetic electrons in

  4. Converging shocks in elastic-plastic solids.

    PubMed

    Ortega, A López; Lombardini, M; Hill, D J

    2011-11-01

    We present an approximate description of the behavior of an elastic-plastic material processed by a cylindrically or spherically symmetric converging shock, following Whitham's shock dynamics theory. Originally applied with success to various gas dynamics problems, this theory is presently derived for solid media, in both elastic and plastic regimes. The exact solutions of the shock dynamics equations obtained reproduce well the results obtained by high-resolution numerical simulations. The examined constitutive laws share a compressible neo-Hookean structure for the internal energy e=e(s)(I(1))+e(h)(ρ,ς), where e(s) accounts for shear through the first invariant of the Cauchy-Green tensor, and e(h) represents the hydrostatic contribution as a function of the density ρ and entropy ς. In the strong-shock limit, reached as the shock approaches the axis or origin r=0, we show that compression effects are dominant over shear deformations. For an isothermal constitutive law, i.e., e(h)=e(h)(ρ), with a power-law dependence e(h) is proportional to ρ(α), shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M is proportional to [log(1/R)](α), independently of the space index s, where s=2 in cylindrical geometry and 3 in spherical geometry. An alternative isothermal constitutive law with p(ρ) of the arctanh type, which enforces a finite density in the strong-shock limit, leads to M is proportional to R(-(s-1)) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part e(h) is that of an ideal gas, is also tested, recovering the strong-shock limit M is proportional to R(-(s-1)/n(γ)) originally derived by Whitham for perfect gases, where γ is inherently related to the maximum compression ratio that the material can reach, (γ+1)/(γ-1). From these strong-shock limits, we also estimate analytically the density, radial velocity, pressure, and sound speed immediately behind the shock. While the

  5. Organic synthesis in experimental impact shocks

    NASA Technical Reports Server (NTRS)

    McKay, C. P.; Borucki, W. J.

    1997-01-01

    Laboratory simulations of shocks created with a high-energy laser demonstrate that the efficacy of organic production depends on the molecular, not just the elemental composition of the shocked gas. In a methane-rich mixture that simulates a low-temperature equilibrium mixture of cometary material, hydrogen cyanide and acetylene were produced with yields of 5 x 10(17) molecules per joule. Repeated shocking of the methane-rich mixture produced amine groups, suggesting the possible synthesis of amino acids. No organic molecules were produced in a carbon dioxide-rich mixture, which is at odds with thermodynamic equilibrium approaches to shock chemistry and has implications for the modeling of shock-produced organic molecules on early Earth.

  6. Numerical simulation of MHD shock waves in the solar wind

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.; Dryer, M.

    1978-01-01

    The effects of the interplanetary magnetic field on the propagation speed of shock waves through an ambient solar wind are examined by numerical solutions of the time-dependent nonlinear equations of motion. The magnetic field always increases the velocity of strong shocks. Although the field may temporarily slow down weak shocks inside 1 AU, it eventually also causes weak shocks to travel faster than they would without the magnetic field at larger distances. Consistent with the increase in the shock velocity, the gas pressure ratio across a shock is reduced considerably in the presence of the magnetic field. The numerical method is used to simulate (starting at 0.3 AU) the large deceleration of a shock observed in the lower corona by ground-based radio instrumentation and the more gradual deceleration of the shock in the solar wind observed by the Pioneer 9 and Pioneer 10 spacecraft.

  7. Nuclear Forensics at Los Alamos National Laboratory

    SciTech Connect

    Podlesak, David W; Steiner, Robert E.; Burns, Carol J.; LaMont, Stephen P.; Tandon, Lav

    2012-08-09

    The overview of this presentation is: (1) Introduction to nonproliferation efforts; (2) Scope of activities at Los Alamos National Laboratory; (3) Facilities for radioanalytical work at LANL; (4) Radiochemical characterization capabilities; and (5) Bulk chemical and materials analysis capabilities. Some conclusions are: (1) Analytical chemistry measurements on plutonium and uranium matrices are critical to numerous defense and non-defense programs including safeguards accountancy verification measurements; (2) Los Alamos National Laboratory operates capable actinide analytical chemistry and material science laboratories suitable for nuclear material forensic characterization; (3) Actinide analytical chemistry uses numerous means to validate and independently verify that measurement data quality objectives are met; and (4) Numerous LANL nuclear facilities support the nuclear material handling, preparation, and analysis capabilities necessary to evaluate samples containing nearly any mass of an actinide (attogram to kilogram levels).

  8. Water Supply at Los Alamos during 1997

    SciTech Connect

    M. N. Maes; S. G. McLin; W. D. Purtymun

    1998-12-01

    Production of potable municipal water supplies during 1997 totaled about 1,285.9 million gallons from wells in the Guaje, Pajarito, and Otowi well fields. There was no water used from the spring gallery in Water Canyon or from Guaje Reservoir during 1997. About 2.4 million gallons of water from Los Alamos Reservoir was used to irrigate public parks and recreational lands. The total water usage in 1997 was about 1,288.3 million gallons, or about 135 gallons per day per person living in Los Alamos County. Groundwater pumpage was down about 82.2 million gallons in 1997 compared with the pumpage in 1996. Four new replacement wells were drilled and cased in Guaje Canyon between October 1997 and March 1998. These wells are currently being developed and aquifer tests are being performed. A special report summarizing the geological, geophysical, and well construction logs will be issued in the near future for these new wells.

  9. Los Alamos Team Demonstrates Bottle Scanner Technology

    ScienceCinema

    Espy, Michelle; Schultz, Larry

    2016-07-12

    Los Alamos scientists are demonstrating a Nuclear Magnetic Resonance Imaging (NMR) technology that may provide a breakthrough for screening liquids at airport security. By adding low-power X-ray data to the NMR mix, scientists believe they have unlocked a new detection technology. Funded in part by the Department of Homeland Security's Science and Technology Directorate, the new technology is called MagRay.

  10. Status of the Los Alamos Anger camera

    SciTech Connect

    Seeger, P.A.; Nutter, M.J.

    1985-01-01

    Results of preliminary tests of the neutron Anger camera being developed at Los Alamos are presented. This detector uses a unique encoding scheme involving parellel processing of multiple receptive fields. Design goals have not yet been met, but the results are very encouraging and improvements in the test procedures are expected to show that the detector will be ready for use on a small-angle scattering instrument next year. 3 refs., 4 figs.

  11. Los Alamos synchronous orbit data set

    SciTech Connect

    Baker, D.N.; Higbie, P.R.; Belian, R.D.; Hones, E.W.; Klebesadel, R.W.

    1981-01-01

    Energetic electron (30-15000 keV) and proton 145 keV to 150 MeV) measurements made by Los Alamos National Laboratory sensors at geostationary orbit (6.6 R/sub E/) are summarized. The instrumentation employed and the satellite positions are described. The spacecraft have been variously located, but in their present configuration the Los Alamos satellites designated 1976-059, 1977-007, and 1979-053 are located, respectively, at approx. 70/sup 0/W, approx. 70/sup 0/E, and approx. 135/sup 0/W longitude. Several examples of the high temporal and full three-dimensional spatial measurement capabilities of these instruments are illustrated by examples from the published literature. Discussion is also given for the Los Alamos Synoptic Data Set (SDS) which gives a broad overview of the Los Alamos geostationary orbit measurements. The SDS data are plotted in terms of daily average spectra, 3-hour local time averages, and in a variety of statistical formats. The data summarize conditions from mid-1976 through 1978 (S/C 1976-059) and from early 1977 through 1978 (S/C 1977-007). The SDS compilations presented correspond to measurements at 35/sup 0/W, 70/sup 0/W, and 135/sup 0/W geographic longitude and thus are indicative of conditions at 9/sup 0/, 11/sup 0/, and 4.8/sup 0/ geomagnetic latitude, respectively. The bulk of the SDS report presents data plots which are organized according to Carrington solar rotations and, as such, the data are readily comparable to solar rotation-dependent interplanetary conditions. Potential applications of the Synoptic Data Set (available to all interested users in June 1981) are discussed.

  12. Amphibians and Reptiles of Los Alamos County

    SciTech Connect

    Teralene S. Foxx; Timothy K. Haarmann; David C. Keller

    1999-10-01

    Recent studies have shown that amphibians and reptiles are good indicators of environmental health. They live in terrestrial and aquatic environments and are often the first animals to be affected by environmental change. This publication provides baseline information about amphibians and reptiles that are present on the Pajarito Plateau. Ten years of data collection and observations by researchers at Los Alamos National Laboratory, the University of New Mexico, the New Mexico Department of Game and Fish, and hobbyists are represented.

  13. Los Alamos Team Demonstrates Bottle Scanner Technology

    SciTech Connect

    Espy, Michelle; Schultz, Larry

    2014-05-06

    Los Alamos scientists are demonstrating a Nuclear Magnetic Resonance Imaging (NMR) technology that may provide a breakthrough for screening liquids at airport security. By adding low-power X-ray data to the NMR mix, scientists believe they have unlocked a new detection technology. Funded in part by the Department of Homeland Security's Science and Technology Directorate, the new technology is called MagRay.

  14. The Los Alamos accelerator code group

    SciTech Connect

    Krawczyk, F.L.; Billen, J.H.; Ryne, R.D.; Takeda, Harunori; Young, L.M.

    1995-05-01

    The Los Alamos Accelerator Code Group (LAACG) is a national resource for members of the accelerator community who use and/or develop software for the design and analysis of particle accelerators, beam transport systems, light sources, storage rings, and components of these systems. Below the authors describe the LAACG`s activities in high performance computing, maintenance and enhancement of POISSON/SUPERFISH and related codes and the dissemination of information on the INTERNET.

  15. Los Alamos Novel Rocket Design Flight Tested

    SciTech Connect

    Tappan, Bryce

    2014-10-23

    Los Alamos National Laboratory scientists recently flight tested a new rocket design that includes a high-energy fuel and a motor design that also delivers a high degree of safety. Researchers will now work to scale-up the design, as well as explore miniaturization of the system, in order to exploit all potential applications that would require high-energy, high-velocity, and correspondingly high safety margins.

  16. Los Alamos Novel Rocket Design Flight Tested

    ScienceCinema

    Tappan, Bryce

    2016-07-12

    Los Alamos National Laboratory scientists recently flight tested a new rocket design that includes a high-energy fuel and a motor design that also delivers a high degree of safety. Researchers will now work to scale-up the design, as well as explore miniaturization of the system, in order to exploit all potential applications that would require high-energy, high-velocity, and correspondingly high safety margins.

  17. Los Alamos National Laboratory Facility Review

    SciTech Connect

    Nelson, Ronald Owen

    2015-06-05

    This series of slides depicts the Los Alamos Neutron Science Center (LANSCE). The Center's 800-MeV linac produces H+ and H- beams as well as beams of moderated (cold to 1 MeV) and unmoderated (0.1 to 600 MeV) neutrons. Experimental facilities and their capabilities and characteristics are outlined. Among these are LENZ, SPIDER, and DANCE.

  18. Multidimensional radiative effects in supercritical shocks

    NASA Astrophysics Data System (ADS)

    Leygnac, S.; Lanz, T.; Stehlé, C.; Michaut, C.; Korĉáková, D.

    Recent radiative shocks experiments performed on the LULI laser at Ecole Polytechnique in France (Fleury et al., Lasers and Particle Beams 20, 263, 2002) put in evidence a supercritical shock wave in a xenon gas cell. The structure of these shocks is quite similar to those of accretion shock wave in the case of stellar formation, as indicated in Stehlé and Chieze (SF2A - Paris proceedings, 2002). Some points require further studies like the contribution of the gas excitation/ionization energy to the compression ratio and the understanding of the discrepancy, which was noted between the velocity of the radiative precursor in the experiment and in the 1D simulation. Thus, to understand the physics of the radiative shock waves, the academic case of the stationary shock is particularly interesting. We have thus studied the structure of a radiative shock wave which propagates in an ionized gas. We study the extended Rankine Hugoniot equations in various media with inclusion of radiation pressure and energy and study also the extension of the radiative precursor in the diffusion approximation. We also study the equations of multidimensional radiative transfer for a snapshot of the experimental shock in xenon in order to quantify the radiative losses in the finite experimental cell. This academic approach will help to improve the knowledge of the physical processes which take place in radiative shocks of astrophysical interest, like in the birth and death of stars, and prepare ourselves to define appropriate experiments on future high power lasers like LIL and LMJ in Bordeaux.

  19. Critical partnerships: Los Alamos, universities, and industry

    SciTech Connect

    Berger, C.L.

    1997-04-01

    Los Alamos National Laboratory, situated 35 miles northwest of Santa Fe, NM, is one of the Department of Energy`s three Defense Programs laboratories. It encompasses 43 square miles, employees approximately 10,000 people, and has a budget of approximately $1.1B in FY97. Los Alamos has a strong post-cold war mission, that of reducing the nuclear danger. But even with that key role in maintaining the nation`s security, Los Alamos views partnerships with universities and industry as critical to its future well being. Why is that? As the federal budget for R&D comes under continued scrutiny and certain reduction, we believe that the triad of science and technology contributors to the national system of R&D must rely on and leverage each others capabilities. For us this means that we will rely on these partners to help us in 5 key ways: We expect that partnerships will help us maintain and enhance our core competencies. In doing so, we will be able to attract the best scientists and engineers. To keep on the cutting edge of research and development, we have found that partnerships maintain the excellence of staff through new and exciting challenges. Additionally, we find that from our university and corporate partners we often learn and incorporate {open_quotes}best practices{close_quotes} in organizational management and operations. Finally, we believe that a strong national system of R&D will ensure and enhance our ability to generate revenues.

  20. Exploration geochemistry: The Los Alamos experience

    SciTech Connect

    Maassen, L.W.; Bolivar, S.L.

    1989-01-01

    Los Alamos National Laboratory became actively involved in geochemical exploration in 1975 by conducting a reconnaissance-scale exploration program for uranium as part of the National Uranium Resource Evaluation program. Initially, only uranium and thorium were analyzed. By 1979 Los Alamos was analyzing a multielement suite. The data were presented in histograms and as black and white concentration plots for uranium and thorium only. Data for the remaining elements were presented as hard copy data listings in an appendix to the report. In 1983 Los Alamos began using exploration geochemistry for the purpose of finding economic mineral deposits to help stimulate the economies of underdeveloped countries. Stream-sediment samples were collected on the Caribbean island of St. Lucia and a geochemical atlas of that island was produced. The data were statistically smoothed and presented as computer-generated color plots of each element of the multielement suite. Studies for the US Bureau of Land Management in 1984 consisted of development of techniques for the integration of several large data sets, which could then be used for computer-assisted mineral resource assessments. A supervised classification technique was developed which compares the attributes of grid cells containing mines or mineral occurrences with attributes of unclassified cells not known to contain mines or occurrences. Color maps indicate how closely unclassified cells match in attributes the cells with mines or occurrences. 20 refs., 1 fig., 1 tab.

  1. Los Alamos National Laboratory building cost index

    SciTech Connect

    Orr, H.D.; Lemon, G.D.

    1982-10-01

    The Los Alamos National Laboratory Building Cost Index indicates that actual escalation since 1970 is near 10% per year. Therefore, the Laboratory will continue using a 10% per year escalation rate for construction estimates through 1985 and a slightly lower rate of 8% per year from 1986 through 1990. The computerized program compares the different elements involved in the cost of a typical construction project, which for our purposes, is a complex of office buildings and experimental laboratories. The input data used in the program consist primarily of labor costs and material and equipment costs. The labor costs are the contractual rates of the crafts workers in the Los Alamos area. For the analysis, 12 field-labor craft categories are used; each is weighted corresponding to the labor craft distribution associated with the typical construction project. The materials costs are current Los Alamos prices. Additional information sources include material and equipment quotes obtained through conversations with vendors and from trade publications. The material and equipment items separate into 17 categories for the analysis and are weighted corresponding to the material and equipment distribution associated with the typical construction project. The building cost index is compared to other national building cost indexes.

  2. Los Alamos National Laboratory Building Cost Index

    SciTech Connect

    Orr, H.D.; Lemon, G.D.

    1983-01-01

    The Los Alamos National Laboratory Building Cost Index indicates that actual escalation since 1970 is near 10% per year. Therefore, the Laboratory will continue using a 10% per year escalation rate for construction estimates through 1985 and a slightly lower rate of 8% per year from 1986 through 1990. The computerized program compares the different elements involved in the cost of a typical construction project, which for our purposes, is a complex of office buildings and experimental laboratores. The input data used in the program consist primarily of labor costs and material and equipment costs. The labor costs are the contractural rates of the crafts workers in the Los Alamos area. For the analysis, 12 field-labor draft categories are used; each is weighted corresponding to the labor craft distribution associated with the typical construction project. The materials costs are current Los Alamos prices. Additional information sources include material and equipment quotes obtained through conversations with vendors and from trade publications. The material and equipment items separate into 17 categories for the analysis and are weighted corresponding to the material and equipment distribution associated with the typical construction project. The building cost index is compared to other national building cost indexes.

  3. EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE

    NASA Technical Reports Server (NTRS)

    Glass, C. E.

    1994-01-01

    New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow

  4. Shock Layer Radiation Measurements and Analysis for Mars Entry

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Grinstead, Jay Henderson; Bogdanoff, David W.; Wright, Michael J.

    2009-01-01

    NASA's In-Space Propulsion program is supporting the development of shock radiation transport models for aerocapture missions to Mars. A comprehensive test series in the NASA Antes Electric Arc Shock Tube facility at a representative flight condition was recently completed. The facility optical instrumentation enabled spectral measurements of shocked gas radiation from the vacuum ultraviolet to the near infrared. The instrumentation captured the nonequilibrium post-shock excitation and relaxation dynamics of dispersed spectral features. A description of the shock tube facility, optical instrumentation, and examples of the test data are presented. Comparisons of measured spectra with model predictions are also made.

  5. 3D model of bow shocks

    NASA Astrophysics Data System (ADS)

    Gustafsson, M.; Ravkilde, T.; Kristensen, L. E.; Cabrit, S.; Field, D.; Pineau Des Forêts, G.

    2010-04-01

    Context. Shocks produced by outflows from young stars are often observed as bow-shaped structures in which the H2 line strength and morphology are characteristic of the physical and chemical environments and the velocity of the impact. Aims: We present a 3D model of interstellar bow shocks propagating in a homogeneous molecular medium with a uniform magnetic field. The model enables us to estimate the shock conditions in observed flows. As an example, we show how the model can reproduce rovibrational H2 observations of a bow shock in OMC1. Methods: The 3D model is constructed by associating a planar shock with every point on a 3D bow skeleton. The planar shocks are modelled with a highly sophisticated chemical reaction network that is essential for predicting accurate shock widths and line emissions. The shock conditions vary along the bow surface and determine the shock type, the local thickness, and brightness of the bow shell. The motion of the cooling gas parallel to the bow surface is also considered. The bow shock can move at an arbitrary inclination to the magnetic field and to the observer, and we model the projected morphology and radial velocity distribution in the plane-of-sky. Results: The morphology of a bow shock is highly dependent on the orientation of the magnetic field and the inclination of the flow. Bow shocks can appear in many different guises and do not necessarily show a characteristic bow shape. The ratio of the H2 v = 2-1 S(1) line to the v = 1-0 S(1) line is variable across the flow and the spatial offset between the peaks of the lines may be used to estimate the inclination of the flow. The radial velocity comes to a maximum behind the apparent apex of the bow shock when the flow is seen at an inclination different from face-on. Under certain circumstances the radial velocity of an expanding bow shock can show the same signatures as a rotating flow. In this case a velocity gradient perpendicular to the outflow direction is a projection

  6. Condensate Accretion in Shock Tube's Expansion Fan

    NASA Technical Reports Server (NTRS)

    Mezonlin, Ephrem-Denis; DeSilva, Upul P.; Hunte, F.; Johnson, Joseph A., III

    1997-01-01

    It has been shown that turbulence and temperature influence the droplet sizes in expansion fan induced condensation by studying the Rayleigh scattering from one port in our shock tube's test section. We have modified our set-up so as to allow, using two ports, the real time measurement of the influence of turbulence and temperature on the rate at which these droplets grow. To do this, we looked at the Rayleigh scattering from two different ports for ten Reynolds numbers at five different temperatures. We modeled the time of flight of droplets, using the equations of one-dimensional gas dynamics and the measured shock wave speed in shock tube's driven section.

  7. Radiative shocks: An opportunity to study laboratory astrophysics

    NASA Astrophysics Data System (ADS)

    Koenig, M.; Vinci, T.; Benuzzi-Mounaix, A.; Ozaki, N.; Ravasio, A.; Rabec Le Glohaec, M.; Boireau, L.; Michaut, C.; Bouquet, S.; Atzeni, S.; Schiavi, A.; Peyrusse, O.; Batani, D.

    2006-05-01

    In this paper, experimental results on radiative shocks generated by a high power laser in a xenon gas cell are presented. Two sets of experiments have been performed at the Laser pour l'Utilisation des Lasers Intenses (LULI) laboratory. Several shock parameters were simultaneously measured: shock temperature and velocities, the precursor two-dimensional (2D) time evolution, its electron density, density gradient, and temperature. Data were obtained varying initial conditions for different laser intensities and gas pressures. Comparisons with 1D and 2D radiative hydrodynamic simulations are shown for all measured parameters (shock velocity, shape, radial expansion, and temperature as well as precursor velocity and electron density).

  8. Characterization of Shocked Beryllium

    SciTech Connect

    Cady, Carl M; Adams, Chris D; Hull, Lawrence M; Gray III, George T; Prime, Michael B; Addessio, Francis L; Wynn, Thomas A; Brown, Eric N

    2012-08-24

    Beryllium metal has many excellent structural properties in addition to its unique radiation characteristics, including: high elastic modulus, low Poisson's ratio, low density, and high melting point. However, it suffers from several major mechanical drawbacks: 1) high anisotropy - due to its hexagonal lattice structure and its susceptibility to crystallographic texturing; 2) susceptibility to impurity-induced fracture - due to grain boundary segregation; and 3) low intrinsic ductility at ambient temperatures thereby limiting fabricability. While large ductility results from deformation under the conditions of compression, the material can exhibit a brittle behavior under tension. Furthermore, there is a brittle to ductile transition at approximately 200 C under tensile conditions. While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. The beryllium used in this study was Grade S200-F (Brush Wellman, Inc., Elmore, OH) material. The work focused on high strain rate deformation and examine the validity of constitutive models in deformation rate regimes, including shock, the experiments were modeled using a Lagrangian hydrocode. Two constitutive strength (plasticity) models, the Preston-Tonks-Wallace (PTW) and Mechanical Threshold Stress (MTS) models, were calibrated using the same set of quasi-static and Hopkinson bar data taken at temperatures from 77K to 873K and strain rates from 0.001/sec to 4300/sec. In spite of being calibrated on the same data, the two models give noticeably different results when compared with the measured wave profiles. These high strain rate tests were conducted using both explosive drive and a gas gun to

  9. Shock finding on a moving mesh - I. Shock statistics in non-radiative cosmological simulations

    NASA Astrophysics Data System (ADS)

    Schaal, Kevin; Springel, Volker

    2015-02-01

    Cosmological shock waves play an important role in hierarchical structure formation by dissipating and thermalizing kinetic energy of gas flows, thereby heating the Universe. Furthermore, identifying shocks in hydrodynamical simulations and measuring their Mach number accurately are critical for calculating the production of non-thermal particle components through diffusive shock acceleration. However, shocks are often significantly broadened in numerical simulations, making it challenging to implement an accurate shock finder. We here introduce a refined methodology for detecting shocks in the moving-mesh code AREPO, and show that results for shock statistics can be sensitive to implementation details. We put special emphasis on filtering against spurious shock detections due to tangential discontinuities and contacts. Both of them are omnipresent in cosmological simulations, for example in the form of shear-induced Kelvin-Helmholtz instabilities and cold fronts. As an initial application of our new implementation, we analyse shock statistics in non-radiative cosmological simulations of dark matter and baryons. We find that the bulk of energy dissipation at redshift zero occurs in shocks with Mach numbers around M≈ 2.7. Furthermore, almost 40 per cent of the thermalization is contributed by shocks in the warm hot intergalactic medium, whereas ≈60 per cent occurs in clusters, groups, and smaller haloes. Compared to previous studies, these findings revise the characterization of the most important shocks towards higher Mach numbers and lower density structures. Our results also suggest that regions with densities above and below δb = 100 should be roughly equally important for the energetics of cosmic ray acceleration through large-scale structure shocks.

  10. Instability of spherically imploding shock waves

    SciTech Connect

    Chen, H.; Hilko, B.; Zhang, L.; Panarella, E.

    1995-12-31

    The importance of spherically imploding shock waves has increased recently due to their particular applications in inertial confinement fusion (ICF) and the Spherical Pinch (SP). In particular, the stability of spherically imploding shock waves plays a critical role in the ultimate success of ICF and SP. The instability of spherically imploding shock waves is now systematically investigated. The basic state is Guderley and Landau`s unsteady self-similar solution of the implosion of a spherical shock wave. The stability analysis is conducted by combining Chandresakhar`s approach to the stability of spherical flames together. The governing equations for disturbances are derived and they use the condition that perturbed gas flow is potential. The three dimensional perturbation velocity profile and a shock front perturbation are solved by using the kinematic and dynamic boundary conditions in the shock front. The time-dependent amplitudes of the perturbations are obtained by solving the system of ordinary differential equations. This enables them to study the time history of the spherically imploding shock wave subject to perturbations. The relative amplification and decay of the amplitudes of perturbations decides the stability/instability of the spherical imploding shock waves. Preliminary results are presented.

  11. DETERMINISTIC TRANSPORT METHODS AND CODES AT LOS ALAMOS

    SciTech Connect

    J. E. MOREL

    1999-06-01

    The purposes of this paper are to: Present a brief history of deterministic transport methods development at Los Alamos National Laboratory from the 1950's to the present; Discuss the current status and capabilities of deterministic transport codes at Los Alamos; and Discuss future transport needs and possible future research directions. Our discussion of methods research necessarily includes only a small fraction of the total research actually done. The works that have been included represent a very subjective choice on the part of the author that was strongly influenced by his personal knowledge and experience. The remainder of this paper is organized in four sections: the first relates to deterministic methods research performed at Los Alamos, the second relates to production codes developed at Los Alamos, the third relates to the current status of transport codes at Los Alamos, and the fourth relates to future research directions at Los Alamos.

  12. Spectral methods for the Euler equations: Chebyshev methods and shock-fitting

    NASA Technical Reports Server (NTRS)

    Hussaini, M. Y.; Kopriva, D. A.; Salas, M. D.; Zang, T. A.

    1984-01-01

    The Chebyshev spectral collocation method for the Euler gas-dynamic equations is described. It is used with shock fitting to compute several two-dimensional, gas-dynamic flows. Examples include a shock-acoustic wave interaction, a shock/vortex interaction, and the classical blunt body problem. With shock fitting, the spectral method has a clear advantage over second order finite differences in that equivalent accuracy can be obtained with far fewer grid points.

  13. Dissolved pesticides in the Alamo River and the Salton Sea, California, 1996-97

    USGS Publications Warehouse

    Crepeau, Kathryn L.; Kuivila, Kathryn M.; Bergamaschi, Brian A.

    2002-01-01

    Water samples were collected from the Alamo River and the Salton Sea, California, in autumn 1996 and late winter/early spring 1997 and analyzed for dissolved pesticides. The two seasons chosen for sampling were during pesticide application periods in the Imperial Valley. Pesticide concentrations were measured in filtered water samples using solid-phase extraction and analyzed by gas chromatography/mass spectrometry. Generally, the highest concentrations were measured in the Alamo River. The concentrations of carbaryl, chlorpyrifos, cycloate, dacthal, diazinon, and eptam were highest in samples collected in autumn 1996. In contrast, the concentrations of atrazine, carbofuran, and malathion were highest in samples collected in late winter/early spring 1997. The highest concentrations measured of atrazine, carbofuran, dacthal, eptam, and malathion all exceeded 1,000 nanograms per liter.

  14. Measurement of the shock front velocity produced in a T-tube

    SciTech Connect

    Djurović, S.; Mijatović, Z.; Vujičić, B.; Kobilarov, R.; Savić, I.; Gavanski, L.

    2015-01-15

    A set of shock front velocity measurements is described in this paper. The shock waves were produced in a small electromagnetically driven shock T-tube. Most of the measurements were performed in hydrogen. The shock front velocity measurements in other gases and the velocity of the gas behind the shock front were also analyzed, as well as the velocity dependence on applied input energy. Some measurements with an applied external magnetic field were also performed. The used method of shock front velocity is simple and was shown to be very reliable. Measured values were compared with the calculated ones for the incident and reflected shock waves.

  15. Modeling the After-Effects of Shocks Toward L1157

    NASA Astrophysics Data System (ADS)

    Burkhardt, Andrew M.; McGuire, Brett A.; Dollhopf, Niklaus M.; Herbst, Eric

    2016-06-01

    Shocks have been found to be ubiquitous throughout the interstellar medium and in star forming regions. How these phenomena affect the chemistry, especially the interplay between gas-phase and grain-surface processes, in these regions has yet to be fully understood. In the prototypical shocked-outflow of L1157, we can study the effects that recent shocks (˜10^3-10^4 years ago) can have on previously cold, quiescent gas, where many of the complex molecules are thought to be locked within grains. Toward a single shock event, C2, a significant chemical differentiation is observed between the previously shocked gas along the eastern wall and the newly shocked gas along the western wall. In addition, substantial enhancement of HNCO towards the younger shock, C1, may imply high-temperature O-chemistry is important soon after the passage of a shock. Here, we utilize the gas-grain chemical network model NAUTILUS in order to investigate the prominence of these effects.

  16. Miniature shock tube for laser driven shocks.

    PubMed

    Busquet, Michel; Barroso, Patrice; Melse, Thierry; Bauduin, Daniel

    2010-02-01

    We describe in this paper the design of a miniature shock tube (smaller than 1 cm(3)) that can be placed in a vacuum vessel and allows transverse optical probing and longitudinal backside extreme ultraviolet emission spectroscopy in the 100-500 A range. Typical application is the study of laser launched radiative shocks, in the framework of what is called "laboratory astrophysics."

  17. Shock & Anaphylactic Shock. Learning Activity Package.

    ERIC Educational Resources Information Center

    Hime, Kirsten

    This learning activity package on shock and anaphylactic shock is one of a series of 12 titles developed for use in health occupations education programs. Materials in the package include objectives, a list of materials needed, information sheets, reviews (self evaluations) of portions of the content, and answers to reviews. These topics are…

  18. Understanding the Shock in "Culture Shock."

    ERIC Educational Resources Information Center

    Schnell, Jim

    "Culture shock" is the expression generally associated with the frustrations that occur when persons have difficulty functioning in a different culture or when persons are exposed to individuals from another culture. Culture shock typically occurs in a 4-stage process that can unfold over varying lengths of time: the honeymoon, crisis, resolution,…

  19. Shock structure and shock heating in the Galactic central molecular zone

    NASA Astrophysics Data System (ADS)

    Ott, Jürgen; Burton, Michael; Jones, Paul; Meier, David S.

    2014-05-01

    We present maps of a large number of dense molecular gas tracers across the central molecular zone of our Galaxy. The data were taken with the CSIRO/CASS Mopra telescope in Large Projects in the 1.3 cm, 7 mm, and 3 mm wavelength regimes. Here, we focus on the brightness of the shock tracers SiO and HNCO, molecules that are liberated from dust grains under strong (SiO) and weak (HNCO) shocks. The shocks may have occurred when the gas enters the bar regions and the shock differences could be due to differences in the moving cloud masses. Based on tracers of ionizing photons, it is unlikely that the morphological differences are due to selective photo-dissociation of the molecules. We also observe direct heating of molecular gas in strongly shocked zones, with high SiO/HNCO ratios, where temperatures are determined from the transitions of ammonia. Strong shocks appear to be the most efficient heating source of molecular gas, apart from high energy emission emitted by the central supermassive black hole Sgr A* and the processes within the extreme star formation region Sgr B2.

  20. Los Alamos Before and After the Fire

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On May 4, 2000, a prescribed fire was set at Bandelier National Monument, New Mexico, to clear brush and dead and dying undergrowth to prevent a larger, subsequent wildfire. Unfortunately, due to high winds and extremely dry conditions in the surrounding area, the prescribed fire quickly raged out of control and, by May 10, the blaze had spread into the nearby town of Los Alamos. In all, more than 20,000 people were evacuated from their homes and more than 200 houses were destroyed as the flames consumed about 48,000 acres in and around the Los Alamos area. The pair of images above were acquired by the Enhanced Thematic Mapper Plus (ETM+) sensor, flying aboard NASA's Landsat 7 satellite, shortly before the Los Alamos fire (top image, acquired April 14) and shortly after the fire was extinguished (lower image, June 17). The images reveal the extent of the damage caused by the fire. Combining ETM+ channels 7, 4, and 2 (one visible and two infrared channels) results in a false-color image where vegetation appears as bright to dark green. Forested areas are generally dark green while herbaceous vegetation is light green. Rangeland or more open areas appear pink to light purple. Areas with extensive pavement or urban development appear light blue or white to purple. Less densely-developed residential areas appear light green and golf courses are very bright green. In the lower image, the areas recently burned appear bright red. Landsat 7 data courtesy United States Geological Survey EROS DataCenter. Images by Robert Simmon, NASA GSFC.

  1. Toxic shock syndrome

    MedlinePlus

    ... of toxic shock syndrome involved women who used tampons during their periods (menstruation). However, today less than half of cases are linked to tampon use. Toxic shock syndrome can also occur with ...

  2. Biological assessment for the effluent reduction program, Los Alamos National Laboratory, Los Alamos, New Mexico

    SciTech Connect

    Cross, S.P.

    1996-08-01

    This report describes the biological assessment for the effluent recution program proposed to occur within the boundaries of Los Alamos National Laboratory. Potential effects on wetland plants and on threatened and endangered species are discussed, along with a detailed description of the individual outfalls resulting from the effluent reduction program.

  3. LAMPF II workshop, Los Alamos National Laboratory, Los Alamos, New Mexico, February 1-4, 1982

    SciTech Connect

    Thiessen, H.A.

    1982-01-01

    This report contains the proceedings of the first LAMPF II Workshop held at Los Alamos February 1 to 4, 1982. Included are the talks that were available in written form. The conclusion of the participants was that there are many exciting areas of physics that will be addressed by such a machine.

  4. Los Alamos National Laboratory strategic directions

    SciTech Connect

    Hecker, S.

    1995-10-01

    It is my pleasure to welcome you to Los Alamos. I like the idea of bringing together all aspects of the research community-defense, basic science, and industrial. It is particularly important in today`s times of constrained budgets and in fields such as neutron research because I am convinced that the best science and the best applications will come from their interplay. If we do the science well, then we will do good applications. Keeping our eye focused on interesting applications will spawn new areas of science. This interplay is especially critical, and it is good to have these communities represented here today.

  5. Experience with confirmation measurement at Los Alamos

    SciTech Connect

    Marshall, R.S.; Wagner, R.P.; Hsue, F.

    1985-01-01

    Confirmation measurements are used at Los Alamos in support of incoming and outgoing shipment accountibility and for support of both at /sup 235/U and Pu inventories. Statistical data are presented to show the consistency of measurements on items of identical composition and on items measured at two facilitis using similar instruments. A description of confirmation measurement techniques used in support of /sup 235/U and Pu inventories and a discussion on the ability of the measurements to identify items with misstated SNM are given.

  6. Materials accounting at Los Alamos National Laboratory

    SciTech Connect

    Roberts, N.J.; Erkkila, B.H.; Kelso, H.F.

    1985-07-20

    The materials accounting system at Los Alamos has evolved from an ''80-column'' card system to a very sophisticated near-real-time computerized nuclear material accountability and safeguards system (MASS). The present hardware was designed and acquired in the late 70's and is scheduled for a major upgrade in fiscal year 1986. The history of the system from 1950 through the DYMAC of the late 70's up to the present will be discussed. The philosophy of the system along with the details of the system will be covered. This system has addressed the integrated problems of management, control, and accounting of nuclear material successfully. 8 refs., 3 figs., 1 tab.

  7. Environmental Programs at Los Alamos National Laboratory

    SciTech Connect

    Jones, Patricia

    2012-07-11

    Summary of this project is: (1) Teamwork, partnering to meet goals - (a) Building on cleanup successes, (b) Solving legacy waste problems, (c) Protecting the area's environment; (2) Strong performance over the past three years - (a) Credibility from four successful Recovery Act Projects, (b) Met all Consent Order milestones, (c) Successful ramp-up of TRU program; (3) Partnership between the National Nuclear Security Administration's Los Alamos Site Office, DOE Carlsbad Field Office, New Mexico Environment Department, and contractor staff enables unprecedented cleanup progress; (4) Continued focus on protecting water resources; and (5) All consent order commitments delivered on time or ahead of schedule.

  8. Los Alamos National Laboratory computer benchmarking 1982

    SciTech Connect

    Martin, J.L.

    1983-06-01

    Evaluating the performance of computing machinery is a continual effort of the Computer Research and Applications Group of the Los Alamos National Laboratory. This report summarizes the results of the group's benchmarking activities performed between October 1981 and September 1982, presenting compilation and execution times as well as megaflop rates for a set of benchmark codes. Tests were performed on the following computers: Cray Research, Inc. (CRI) Cray-1S; Control Data Corporation (CDC) 7600, 6600, Cyber 73, Cyber 825, Cyber 835, Cyber 855, and Cyber 205; Digital Equipment Corporation (DEC) VAX 11/780 and VAX 11/782; and Apollo Computer, Inc., Apollo.

  9. SUBMILLIMETER ARRAY/PLATEAU DE BURE INTERFEROMETER MULTIPLE LINE OBSERVATIONS OF THE NEARBY SEYFERT 2 GALAXY NGC 1068: SHOCK-RELATED GAS KINEMATICS AND HEATING IN THE CENTRAL 100 pc?

    SciTech Connect

    Krips, M.; Neri, R.; Martin, S. E-mail: neri@iram.fr

    2011-07-20

    We present high angular resolution (0.''5-2.''0) observations of the millimeter continuum and the {sup 12}CO(J = 3-2), {sup 13}CO(J = 3-2), {sup 13}CO(J = 2-1), C{sup 18}O(J = 2-1), HCN(J = 3-2), HCO{sup +}(J = 4-3), and HCO{sup +}(J = 3-2) line emission in the circumnuclear disk (r {approx}< 100 pc) of the prototypical Seyfert 2 galaxy NGC 1068, carried out with the Submillimeter Array. We also include in our analysis new {sup 13}CO(J = 1-0) and improved {sup 12}CO(J = 2-1) observations of NGC 1068 at high angular resolution (1.''0-2.''0) and sensitivity, conducted with the Institute de Radioastronomie Millimetrique Plateau de Bure Interferometer. Based on the complex dynamics of the molecular gas emission indicating non-circular motions in the central {approx}100 pc, we propose a scenario in which part of the molecular gas in the circumnuclear disk of NGC 1068 is blown radially outward as a result of shocks. This shock scenario is further supported by quite warm (T{sub kin} {>=} 200 K) and dense (n(H{sub 2}) {approx_equal} 10{sup 4} cm{sup -3}) gas constrained from observed molecular line ratios. The HCN abundance in the circumnuclear disk is found to be [HCN]/[{sup 12}CO] {approx} 10{sup -3.5}. This is slightly higher than the abundances derived for Galactic and extragalactic star-forming/starbursting regions. This result lends further support to X-ray-enhanced HCN formation in the circumnuclear disk of NGC 1068 as suggested by earlier studies. The HCO{sup +} abundance ([HCO{sup +}]/[{sup 12}CO] {approx} 10{sup -5}) appears to be somewhat lower than that of Galactic and extragalactic star-forming/starbursting regions. When trying to fit the centimeter-to-millimeter continuum emission by different thermal and non-thermal processes, it appears that electron-scattered synchrotron emission yields the best results while thermal free-free emission seems to overpredict the millimeter continuum emission.

  10. Biomass shock pretreatment

    DOEpatents

    Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

    2014-07-01

    Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

  11. Mean free path effects in the shock-implosion problem

    NASA Astrophysics Data System (ADS)

    Goldsworthy, M. J.; Pullin, D. I.

    2009-02-01

    The effects of finite Knudsen number in the problem of a cylindrically imploding shock wave in a monatomic gas are investigated. Numerical solutions of the flow field are obtained with initial conditions in the ranges 1.25≤M0≤5 and 0.005≤Kn0≤0.1 using the direct simulation Monte Carlo method. Results show that as Kn0 decreases and M0 increases, the maximum implosion temperature scales increasingly well with the similarity exponent predicted in the Guderley solution for an imploding strong shock in the Euler limit. When the radius of curvature is large, the cylindrical shock thickness is found to be almost identical to the thickness of a planar shock for a given shock Mach number. For small radii of curvature, the cylindrical shock was found to be thicker than the corresponding planar shock.

  12. Shock compression of liquid helium to 56 GPa (560 kbar)

    SciTech Connect

    Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Trainor, R.J.; Governo, G.K.; Ross, M.; Young, D.A.

    1984-09-24

    The first shock-compression experiments on liquid helium are reported. With a two-stage light-gas gun, liquid He at 4.3 K and 1 atm was shocked to 16 GPa and 12 000 K and double shocked to 56 GPa and 21 000 K. Liquid perturbation theory has been used to determine an effective interatomic potential from which the equation of state of He can be obtained over a wide range of densities and temperatures.

  13. What Causes Cardiogenic Shock?

    MedlinePlus

    ... page from the NHLBI on Twitter. What Causes Cardiogenic Shock? Immediate Causes Cardiogenic shock occurs if the heart suddenly can't pump ... to the body. The most common cause of cardiogenic shock is damage to the heart muscle from a ...

  14. Chronology and shock history of the Bencubbin meteorite: A nitrogen, noble gas, and Ar-Ar investigation of silicates, metal and fluid inclusions

    NASA Astrophysics Data System (ADS)

    Marty, Bernard; Kelley, Simon; Turner, Grenville

    2010-11-01

    We have investigated the distribution and isotopic composition of nitrogen and noble gases, and the Ar-Ar chronology of the Bencubbin meteorite. Gases were extracted from different lithologies by both stepwise heating and vacuum crushing. Significant amounts of gases were found to be trapped within vesicles present in silicate clasts. Results indicate a global redistribution of volatile elements during a shock event caused by an impactor that collided with a planetary regolith. A transient atmosphere was created that interacted with partially or totally melted silicates and metal clasts. This atmosphere contained 15N-rich nitrogen with a pressure ⩾3 × 10 5 hPa, noble gases, and probably, although not analyzed here, other volatile species. Nitrogen and noble gases were re-distributed among bubbles, metal, and partly or totally melted silicates, according to their partition coefficients among these different phases. The occurrence of N 2 trapped in vesicles and dissolved in silicates indicates that the oxygen fugacity ( fO2) was greater than the iron-wüstite buffer during the shock event. Ar-Ar dating of Bencubbin glass gives an age of 4.20 ± 0.05 Ga, which probably dates this impact event. The cosmic-ray exposure age is estimated at ˜40 Ma with two different methods. Noble gases present isotopic signatures similar to those of "phase Q" (the major host of noble gases trapped in chondrites) but elemental patterns enriched in light noble gases (He, Ne and Ar) relative to Kr and Xe, normalized to the phase Q composition. Nitrogen isotopic data together with 40Ar/ 36Ar ratios indicate mixing between a 15N-rich component (δ 15N = +1000‰), terrestrial N, and an isotopically normal, chondritic N. Bencubbin and related 15N-rich meteorites of the CR clan do not show stable isotope (H and C) anomalies, precluding contribution of a nucleosynthetic component as the source of 15N enrichments. This leaves two possibilities, trapping of an ancient, highly fractionated

  15. NMR spectroscopy of experimentally shocked single crystal quartz: A reexamination of the NMR shock barometer

    NASA Technical Reports Server (NTRS)

    Fiske, P. S.; Gratz, A. J.; Nellis, W. J.

    1993-01-01

    Cygan and others report a broadening of the Si-29 nuclear magnetic resonance (NMR) peak for synthetic quartz powders with increasing shock pressure which they propose as a shock wave barometer for natural systems. These results are expanded by studying single crystal quartz shocked to 12 and 33 GPa using the 6.5 m two-stage light-gas gun at Lawrence Livermore National Laboratories. Our NMR results differ substantially from those of Cygan and others and suggest that the proposed shock wave barometer may require refinement. The difference in results between this study and that of Cygan and others is most likely caused by different starting materials (single crystal vs. powder) and different shock loading histories. NMR results from single crystal studies may be more applicable to natural systems.

  16. Mitigation of Shocks by Finely Dispersed Particles

    NASA Astrophysics Data System (ADS)

    Schwer, D. A.; Kailasanath, K.

    2002-11-01

    Effectively minimizing the damage due to onboard explosions and blast waves on naval ships has always been a priority to the Navy. Water mist presents a clean method for mitigating the effects of the blast wave. However, the effectiveness of water mist in mitigating blast waves is not well understood. As a first step towards determining the effectiveness of water droplets on mitigating blasts, we investigate the ability of particles and droplets to mitigate shock waves in tubes. An explicit, unsteady, flux-corrected transport technique is used for the gas-phase conservation equations, and an Eulerian sectional approach is used for the dispersed-phase. The sectional approach accounts for drag, heat-transfer from the gas to the particles using an infinite conductivity model, and vaporization of the particles. Shock-tube simulations were carried out to match an experimental set up for which some data on shock interaction with particles is available. Several simulations were conducted to examine the effects of driver section length, particle size, heat-transfer effects, and vaporization effects on the mitigation of the front shock, to give a full picture of the mitigation process and the important parameters and processes. Results are in good agreement with available data and suggest that for all cases with particles the shock is slowed, reaching an "equilibrium" shock Mach number far downstream of the original diaphragm.

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

    PubMed

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

    2014-02-21

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

  18. Thermophysical properties of multi-shock compressed dense argon

    SciTech Connect

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

    2014-02-21

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

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

    PubMed

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

    2014-02-21

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

  20. The Climate at Los Alamos; Are we measurement changes?

    SciTech Connect

    Dewart, Jean Marie

    2015-04-16

    A new report shows new graphic displays of the weather trends in Los Alamos, New Mexico, and at the Los Alamos National Laboratory (LANL). The graphs show trends of average, minimum average, and maximum average temperature for summer and winter months going back decades. Records of summer and winter precipitation are also included in the report.

  1. Detonation in shocked homogeneous high explosives

    SciTech Connect

    Yoo, C.S.; Holmes, N.C.; Souers, P.C.

    1995-11-01

    We have studied shock-induced changes in homogeneous high explosives including nitromethane, tetranitromethane, and single crystals of pentaerythritol tetranitrate (PETN) by using fast time-resolved emission and Raman spectroscopy at a two-stage light-gas gun. The results reveal three distinct steps during which the homogeneous explosives chemically evolve to final detonation products. These are (1) the initiation of shock compressed high explosives after an induction period, (2) thermal explosion of shock-compressed and/or reacting materials, and (3) a decay to a steady-state representing a transition to the detonation of uncompressed high explosives. Based on a gray-body approximation, we have obtained the CJ temperatures: 3800 K for nitromethane, 2950 K for tetranitromethane, and 4100 K for PETN. We compare the data with various thermochemical equilibrium calculations. In this paper we will also show a preliminary result of single-shot time-resolved Raman spectroscopy applied to shock-compressed nitromethane.

  2. Estimate of shock thickness based on entropy production

    NASA Astrophysics Data System (ADS)

    Thompson, P. A.; Strock, T. W.; Lim, D. S.

    1983-01-01

    The shock thickness is estimated for a stationary shock in an ideal gas by equating the internal entropy production to the entropy increase found from the Rankine-Hugoniot equation. For elementary assumed profiles, the thickness is expressed by a simple formula. For realistic dependence of viscosity on temperature, results are in qualitative agreement with experiment.

  3. Laser-launched flyer plates and direct laser shocks for dynamic material property measurements

    NASA Astrophysics Data System (ADS)

    Paisley, Dennis; Swift, Damian; Johnson, Randall; Kopp, Roger; Kyrala, George

    2001-06-01

    The Trident laser at Los Alamos was used to impart known and controlled shocks in various materials by launching flyer plates or by irradiating the sample directly. Materials investigated include copper, gold, NiTi, SS316, and other metals and alloys. Tensile spall strength, elastic-plastic transition, phase boundaries, and equation of state can be determined with small samples. Using thin samples (0.1 - 1.0 mm thick) as targets, high pressure gradients can be generated with relatively low pressures, resulting in high tensile strain rates (10^5 to 10^8 s-1). Free surface and interface velocities are recorded with point- and line-imaging VISARs. The flexible spatial and temporal pulse profiles of Trident, coupled with the use of laser-launched flyer plates, provides capabilities which complement experiments conducted using gas guns and tensile bars. These samples spalled at high strain rates will be compared with samples spalled at lower strain rates to elucidate mechanisms for the initiation and growth of spall.

  4. Occurrences at Los Alamos National Laboratory: What can they tell us?

    SciTech Connect

    Richard A. Reichelt; A. Jeffery Eichorst; Marc E. Clay; Rita J. Henins; Judith D. DeHaven; Richard J. Brake

    2000-03-01

    The authors analyzed the evolution of institutional and facility response to groups of abnormal incidents at Los Alamos National Laboratory (LANL). The analysis is divided into three stages: (1) the LANL response to severe accidents from 1994 to 1996, (2) the LANL response to facility-specific clusters of low-consequence incidents from 1997 to 1999, and (3) the ongoing development of and response to a Laboratory-wide trending and analysis program. The first stage is characterized by five severe accidents at LANL--a shooting fatality, a forklift accident, two electrical shock incidents, and an explosion in a nuclear facility. Each accident caused LANL and the Department of Energy (DOE) to launch in-depth investigations. A recurrent theme of the investigations was the failure of LANL and DOE to identify and act on precursor or low-consequence events that preceded the severe accidents. The second stage is characterized by LANL response to precursor or low-consequence incidents over a two-year period. In this stage, the Chemistry and Metallurgy Research Facility, the Los Alamos Critical Experiments Facility, and the Los Alamos Neutron Science Center responded to an increase in low-consequence events by standing down their facilities. During the restart process, each facility collectively analyzed the low-consequence events and developed systemic corrective actions. The third stage is characterized by the development of a Laboratory-wide trending and analysis program, which involves proactive division-level analysis of incidents and development of systemic actions. The authors conclude that, while the stages show an encouraging evolution, the facility standdowns and restarts are overly costly and that the institutional trending and analysis program is underutilized. The authors therefore recommend the implementation of an institutional, mentored program of trending and analysis that identifies clusters of related low-consequence events, analyzes those events, and

  5. A merger shock in A2034

    SciTech Connect

    Owers, Matt S.; Couch, Warrick J.; Hopkins, Andrew M.; Nulsen, Paul E. J.; Ma, Cheng-Jiun; David, Laurence P.; Forman, William R.; Jones, Christine; Van Weeren, Reinout J.

    2014-01-10

    We present a 250 ks Chandra observation of the cluster merger A2034 with the aim of understanding the nature of a sharp edge previously characterized as a cold front. The new data reveal that the edge is coherent over a larger opening angle and is significantly more bow-shock-shaped than previously thought. Within ∼27° about the axis of symmetry of the edge, the density, temperature, and pressure drop abruptly by factors of 1.83{sub −0.08}{sup +0.09}, 1.85{sub −0.41}{sup +0.41}, and 3.4{sub −0.7}{sup +0.8}, respectively. This is inconsistent with the pressure equilibrium expected of a cold front and we conclude that the edge is a shock front. We measure a Mach number M=1.59{sub −0.07}{sup +0.06} and corresponding shock velocity v {sub shock} ≅ 2057 km s{sup –1}. Using spectra collected at the MMT with the Hectospec multi-object spectrograph, we identify 328 spectroscopically confirmed cluster members. Significantly, we find a local peak in the projected galaxy density associated with a bright cluster galaxy that is located just ahead of the nose of the shock. The data are consistent with a merger viewed within ∼23° of the plane of the sky. The merging subclusters are now moving apart along a north-south axis approximately 0.3 Gyr after a small impact parameter core passage. The gas core of the secondary subcluster, which was driving the shock, appears to have been disrupted by the merger. Without a driving 'piston,' we speculate that the shock is dying. Finally, we propose that the diffuse radio emission near the shock is due to the revival of pre-existing radio plasma that has been overrun by the shock.

  6. Portable MRI developed at Los Alamos

    SciTech Connect

    Espy, Michelle

    2015-04-22

    Scientists at Los Alamos National Laboratory are developing an ultra-low-field Magnetic Resonance Imaging (MRI) system that could be low-power and lightweight enough for forward deployment on the battlefield and to field hospitals in the World's poorest regions. "MRI technology is a powerful medical diagnostic tool," said Michelle Espy, the Battlefield MRI (bMRI) project leader, "ideally suited for imaging soft-tissue injury, particularly to the brain." But hospital-based MRI devices are big and expensive, and require considerable infrastructure, such as large quantities of cryogens like liquid nitrogen and helium, and they typically use a large amount of energy. "Standard MRI machines just can't go everywhere," said Espy. "Soldiers wounded in battle usually have to be flown to a large hospital and people in emerging nations just don't have access to MRI at all. We've been in contact with doctors who routinely work in the Third World and report that MRI would be extremely valuable in treating pediatric encephalopathy, and other serious diseases in children." So the Los Alamos team started thinking about a way to make an MRI device that could be relatively easy to transport, set up, and use in an unconventional setting. Conventional MRI machines use very large magnetic fields that align the protons in water molecules to then create magnetic resonance signals, which are detected by the machine and turned into images. The large magnetic fields create exceptionally detailed images, but they are difficult and expensive to make. Espy and her team wanted to see if images of sufficient quality could be made with ultra-low-magnetic fields, similar in strength to the Earth's magnetic field. To achieve images at such low fields they use exquisitely sensitive detectors called Superconducting Quantum Interference Devices, or SQUIDs. SQUIDs are among the most sensitive magnetic field detectors available, so interference with the signal is the primary stumbling block. "SQUIDs are

  7. Finite Time Shock Acceleration at Interplanetary Shocks

    NASA Astrophysics Data System (ADS)

    Channok, C.; Ruffolo, D.; Desai, M. I.; Mason, G. M.

    2004-05-01

    Observations of energetic ion acceleration at interplanetary shocks sometimes indicate a spectral rollover at ˜ 0.1 to 1 MeV nucl-1. This rollover is not well explained by finite shock width or thickness effects. At the same time, a typical timescale of diffusive shock acceleration is several days, implying that the process of shock acceleration at an interplanetary shock near Earth usually gives only a mild increase in energy to an existing seed particle population. This is consistent with a recent analysis of ACE observations that argues for a seed population at substantially higher energies than the solar wind. Therefore an explanation of typical spectra of interplanetary shock-accelerated ions requires a theory of finite-time shock acceleration, which for long times (or an unusually fast acceleration timescale) tends to the steady-state result of a power-law spectrum. We present analytic and numerical models of finite-time shock acceleration. For a given injection momentum p0, after a very short time there is only a small boost in momentum, at intermediate times the spectrum is a power law with a hump and steep cutoff at a critical momentum, and at longer times the critical momentum increases and the spectrum approaches the steady-state power law. The composition dependence of the critical momentum is different from that obtained for other cutoff mechanisms. The results are compared with observed spectra. Work in Thailand was supported by the Commission for Higher Education, the Rachadapisek Sompoj Fund of Chulalongkorn University, and the Thailand Research Fund. Work at the University of Maryland was supported by NASA contract NAS5-30927 and NASA grant PC 251428.

  8. Water in Shocks and Outflows

    NASA Astrophysics Data System (ADS)

    Neufeld, D. A.; Melnick, G. J.; Stauffer, J. R.; Ashby, M. L. N.; Bergin, E. A.; Kleiner, S. C.; Patten, B. M.; Plume, R.; Tolls, V.; Wang, Z.; Zhang, Y. F.; Goldsmith, P. F.; Harwit, M.; Erickson, N. R.; Howe, J. E.; Snell, R. L.; Koch, D. G.; Schieder, R.; Winnewisser, G.; Chin, G.

    1999-12-01

    We have observed water vapor emission from several protostellar outflow regions with SWAS, including the sources Orion-KL, NGC 2071, NGC 1333 IRAS 4, L1157, RCrA, and L1689N. Observations of the 110}-1{01 water transition toward each of these sources have revealed the presence of broad line emission accompanied by narrow absorption in quiescent foreground gas or -- in the case of Orion-KL, by a narrow emission line component. In each case, the width of the broad emission line component, typically 20 - 40 km s-1 (FWHM), suggests an origin in the outflowing gas. From the observed line fluxes, we estimate water abundances ranging from 10-6 in low mass outflow regions to several x 10-4 in the Orion-KL region. These values are all significantly larger than the water abundance estimates of few x 10-9 - 10-7 derived from SWAS observations of quiescent regions, implying that the water abundances are enhanced in outflow regions. Such enhancements are indeed expected to result from the effects of shocks in (1) vaporizing icy grain mantles and/or (2) producing water in the gas-phase (by means of neutral-neutral reactions that are negligibly slow at the low temperatures of quiescent clouds but rapid at the elevated temperatures present behind a shock.)

  9. Simulations of Embedded Electromagnetic Particle Velocity Gauge Package Response in Gas-Gun Experiments

    NASA Astrophysics Data System (ADS)

    Finn, K. L.; James, H. R.; Whitworth, N. J.; Handley, C. A.

    2009-12-01

    In recent years a comprehensive suite of gas-gun particle velocity gauge experiments have been conducted at Los Alamos National Laboratory. Detailed analysis of this data has led to advances in the understanding of the shock to detonation transition in polymer bonded explosives hydrocode simulations of the experiments are frequently used to calibrate reactive-burn models. In these simulations the gauges are modelled using Lagrangian markers with no physical representation of the gauge package. In contrast the experimental gauge package consists of etched aluminium sandwiched between two sheets of FEP Teflon using an urethane-based glue. The gauge package is approximately 60 μm thick is positioned between two wedge-shaped pieces of explosive at an angle of 30 degrees to form a right circular cylinder. This paper investigates with one-dimensional calculations whether there is a need to include an accurate representation of the gauge package within future hydrocode simulations.

  10. Numerical study of non-equilibrium gas flows with shock waves by using the Navier-Stokes equations in the two-temperature approximation

    NASA Astrophysics Data System (ADS)

    Shoev, Georgy; Bondar, Yevgeniy

    2016-10-01

    Validation of various models of vibration-dissociation coupling for simulating high-enthalpy non-equilibrium gas flows of binary mixtures of oxygen O2/O and nitrogen N2/N is discussed. Numerical simulations are based on the Navier-Stokes equations in the two-temperature approximation. The rate of VT-exchange is computed by a modification of the Landau-Teller formula, which was derived from the kinetic Boltzmann equation. The dissociation rate is calculated by different two-temperature models: β-model, Marrone-Treanor, Macheret-Fridman, Kuznetsov, and Park models. Numerical results are compared with available experimental measurements.

  11. Shock wave absorber having a deformable liner

    DOEpatents

    Youngdahl, C.K.; Wiedermann, A.H.; Shin, Y.W.; Kot, C.A.; Ockert, C.E.

    1983-08-26

    This invention discloses a shock wave absorber for a piping system carrying liquid. The absorber has a plastically deformable liner defining the normal flow boundary for an axial segment of the piping system, and a nondeformable housing is spaced outwardly from the liner so as to define a gas-tight space therebetween. The flow capacity of the liner generally corresponds to the flow capacity of the piping system line, but the liner has a noncircular cross section and extends axially of the piping system line a distance between one and twenty times the diameter thereof. Gas pressurizes the gas-tight space equal to the normal liquid pressure in the piping system. The liner has sufficient structural capacity to withstand between one and one-half and two times this normal liquid pressures; but at greater pressures it begins to plastically deform initially with respect to shape to a more circular cross section, and then with respect to material extension by circumferentially stretching the wall of the liner. A high energy shock wave passing through the liner thus plastically deforms the liner radially into the gas space and progressively also as needed in the axial direction of the shock wave to minimize transmission of the shock wave beyond the absorber.

  12. Environmental surveillance at Los Alamos during 1987

    SciTech Connect

    Not Available

    1988-05-01

    This report describes the environmental surveillance program conducted by Los Alamos National Laboratory during 1987. Routine monitoring for radiation and radioactive or chemical materials is conducted on the Laboratory site as well as in the surrounding region. Monitoring results are used to determine compliance with appropriate standards and to permit early identification of potentially undesirable trends. Results and interpretation of data for 1987 cover: external penetrating radiation; quantities of airborne emissions and liquid effluents; concentrations of chemicals and radionuclides in ambient air, surface and ground waters, municipal water supply, soils and sediments, and foodstuffs; and environmental compliance. Comparisons with appropriate standards, regulations, and background levels provide the basis for concluding that environmental effects from Laboratory operations are insignificant and do not pose a threat to the public, Laboratory employees, or the environment. 113 refs., 33 figs., 120 tabs.

  13. Environmental surveillance at Los Alamos during 1995

    SciTech Connect

    1996-10-01

    This report describes the environmental surveillance program at Los Alamos National Laboratory (LANL or the Laboratory) during 1995. The Laboratory routinely monitors for radiation and for radioactive and nonradioactive materials at (or on) Laboratory sites as well as in the surrounding region. LANL uses the monitoring result to determine compliance with appropriate standards and to identify potentially undesirable trends. Data were collected in 1995 to assess external penetrating radiation; quantities of airborne emissions and liquid effluents; concentrations of chemicals and radionuclides in ambient air, surface waters and groundwaters, municipal water supply, soils and sediments, and foodstuffs; and environmental compliance. Using comparisons with standards, regulations, and background levels, this report concludes that environmental effects from Laboratory operations are small and do not pose a demonstrable threat to the public, Laboratory employees, or the environment.

  14. Environmental surveillance at Los Alamos during 1979

    SciTech Connect

    Not Available

    1980-04-01

    This report documents the environmental surveillance program conducted by the Los Alamos Scientific Laboratory (LASL) in 1979. Routine monitoring for radiation and radioactive or chemical substances was conducted on the Laboratory site and in the surrounding region to determine compliance with appropriate standards and permit early identification of possible undesirable trends. Results and interpretation of the data for 1979 on penetrating radiation, chemical and radiochemical quality of ambient air, surface and ground water, municipal water supply, soils and sediments, food, and airborne and liquid effluents are included. Comparisons with appropriate standards and regulations or with background levels from natural or other non-LASL sources provide a basis for concluding that environmental effects attributable to LASL operations are minor and cannot be considered likely to result in any hazard to the population of the area. Results of several special studies provide documentation of some unique environmental conditions in the LASL environs.

  15. Environmental surveillance at Los Alamos during 1989

    SciTech Connect

    Not Available

    1990-12-01

    This report describes the environmental surveillance program conducted by Los Alamos National Laboratory during 1989. Routine monitoring for radiation and radioactive or chemical materials is conducted on the Laboratory site as well as in the surrounding region. Monitoring results are used to determine compliance with appropriate standards and to permit early identification of potentially undesirable trends. Results and interpretation of data for 1989 cover external penetrating radiation; quantities of airborne emissions and effluents; concentrations of chemicals and radionuclides in ambient air, surface and ground waters, municipal water supply, soils and sediments, and foodstuffs; and environmental compliance. Comparisons with appropriate standards, regulations, and background levels provide the basis for concluding that environmental effects from Laboratory operations are small and do not pose a threat to the public, Laboratory employees, or the environment. 58 refs., 31 figs., 39 tabs.

  16. Environmental surveillance at Los Alamos during 1992

    SciTech Connect

    Kohen, K.; Stoker, A.; Stone, G.

    1994-07-01

    This report describes the environmental surveillance program at Los Alamos National Laboratory during 1992. The Laboratory routinely monitors for radiation and for radioactive and nonradioactive materials at (or on) Laboratory sites as well as in the surrounding region. LANL uses the monitoring results to determine compliance with appropriate standards and to identify potentially undesirable trends. Data were collected in 1992 to assess external penetrating radiation; quantities of airborne emissions and liquid effluents; concentrations of chemicals and radionuclides in ambient air, surface waters and groundwaters, municipal water supply, soils and sediments, and foodstuffs; and environmental compliance. Using comparisons with standards, regulations, and background levels, this report concludes that environmental effects from Laboratory operations are small and do not pose a demonstrable threat to the public, laboratory employees, or the environment.

  17. The Los Alamos Intense Neutron Source

    SciTech Connect

    Nebel, R.A.; Barnes, D.C.; Bollman, R.; Eden, G.; Morrison, L.; Pickrell, M.M.; Reass, W.

    1997-10-01

    The Intense Neutron Source (INS) is an Inertial Electrostatic Confinement (IEC) fusion device presently under construction at Los Alamos National Laboratory. It is designed to produce 10{sup 11} neutrons per second steady-state using D-T fuel. Phase 1 operation of this device will be as a standard three grid IEC ion focus device. Expected performance has been predicted by scaling from a previous IEC device. Phase 2 operation of this device will utilize a new operating scheme, the Periodically Oscillating Plasma Sphere (POPS). This scheme is related to both the Spherical Reflect Diode and the Oscillating Penning Trap. With this type of operation the authors hope to improve plasma neutron production to about 10{sup 13} neutrons/second.

  18. Information about Practicums at Los Alamos

    SciTech Connect

    Bradley, Paul A.

    2012-07-24

    The Los Alamos Neutron Science Center is the premier facility for neutron science experiments ranging from cross section measurements, neutron scattering experiments, proton radiography, cold neutrons, actinide neutronic properties, and many other exciting topics. The National High Magnetic Field Laboratory is home to several powerful magnets, including the one that created the first non-destructive 100 Tesla field in March 2012. They probe the electronic structure of superconductors, magnetic properties of materials (including magneto-quantum effects). Research is also conducted in correlated materials, thermoacoustics, and magnetic properties of actinides. The Trident Laser has a unique niche with very high power, short pulse experiments, with a peak power of 10{sup 20} W in short pulse mode. Discoveries range from production of monoenergetic MeV ion beam, nonlinear kinetic plasma waves, the transition between kinetic and fluid nonlinear behavior and other laser-plasma interaction processes.

  19. Interaction of turbulent plasma flow with a hypersonic shock wave

    SciTech Connect

    Belay, K.; Valentine, J.M.; Williams, R.L.; Johnson, J.A. III

    1997-02-01

    A transient increase is observed in both the spectral energy decay rate and the degree of chaotic complexity at the interface of a shock wave and a turbulent ionized gas. Even though the gas is apparently brought to rest by the shock wave, no evidence is found either of prompt relaminarization or of any systematic influence of end-wall material thermal conductivities on the turbulence parameters. {copyright} {ital 1997 American Institute of Physics.}

  20. Environmental analysis of Lower Pueblo/Lower Los Alamos Canyon, Los Alamos, New Mexico

    SciTech Connect

    Ferenbaugh, R.W.; Buhl, T.E.; Stoker, A.K.; Becker, N.M.; Rodgers, J.C.; Hansen, W.R.

    1994-12-01

    The radiological survey of the former radioactive waste treatment plant site (TA-45), Acid Canyon, Pueblo Canyon, and Los Alamos Canyon found residual contamination at the site itself and in the channel and banks of Acid, Pueblo, and lower Los Alamos Canyons all the way to the Rio Grande. The largest reservoir of residual radioactivity is in lower Pueblo Canyon, which is on DOE property. However, residual radioactivity does not exceed proposed cleanup criteria in either lower Pueblo or lower Los Alamos Canyons. The three alternatives proposed are (1) to take no action, (2) to construct a sediment trap in lower Pueblo Canyon to prevent further transport of residual radioactivity onto San Ildefonso Indian Pueblo land, and (3) to clean the residual radioactivity from the canyon system. Alternative 2, to cleanup the canyon system, is rejected as a viable alternative. Thousands of truckloads of sediment would have to be removed and disposed of, and this effort is unwarranted by the low levels of contamination present. Residual radioactivity levels, under either present conditions or projected future conditions, will not result in significant radiation doses to persons exposed. Modeling efforts show that future transport activity will not result in any residual radioactivity concentrations higher than those already existing. Thus, although construction of a sediment trap in lower Pueblo Canyon is a viable alternative, this effort also is unwarranted, and the no-action alternative is the preferred alternative.

  1. Historical Background of Ultrahigh Pressure Shock Compression Experiments at LLNL: 1973 to 2000

    SciTech Connect

    Nellis, W.J.

    2000-10-09

    My purpose is to recount the historical development of ultrahigh pressure shock compression experiments at LLNL, which I experienced in the period 1973 to 2000. I used several experimental techniques: shock-impedance-match experiments using planar shock waves driven by nuclear explosives (NIMs), the Janus Laser, a railgun, and a two-stage light-gas gun.

  2. Environmental surveillance at Los Alamos during 2009

    SciTech Connect

    Fuehne, David; Poff, Ben; Hjeresen, Denny; Isaacson, John; Johnson, Scot; Morgan, Terry; Paulson, David; Salzman, Sonja; Rogers, David

    2010-09-30

    Environmental Surveillance at Los Alamos reports are prepared annually by the Los Alamos National Laboratory (the Laboratory) environmental organization, as required by US Department of Energy Order 5400.1, General Environmental Protection Program, and US Department of Energy Order 231.1A, Environment, Safety, and Health Reporting. These annual reports summarize environmental data that are used to determine compliance with applicable federal, state, and local environmental laws and regulations, executive orders, and departmental policies. Additional data, beyond the minimum required, are also gathered and reported as part of the Laboratory’s efforts to ensure public safety and to monitor environmental quality at and near the Laboratory. Chapter 1 provides an overview of the Laboratory’s major environmental programs and explains the risks and the actions taken to reduce risks at the Laboratory from environmental legacies and waste management operations. Chapter 2 reports the Laboratory’s compliance status for 2009. Chapter 3 provides a summary of the maximum radiological dose the public and biota populations could have potentially received from Laboratory operations and discusses chemical exposures. The environmental surveillance and monitoring data are organized by environmental media (air in Chapter 4; water and sediments in Chapters 5 and 6; soils in Chapter 7; and foodstuffs and biota in Chapter 8) in a format to meet the needs of a general and scientific audience. Chapter 9 provides a summary of the status of environmental restoration work around LANL. The new Chapter 10 describes the Laboratory’s environmental stewardship efforts and provides an overview of the health of the Rio Grande. A glossary and a list of acronyms and abbreviations are in the back of the report. Appendix A explains the standards for environmental contaminants, Appendix B explains the units of measurements used in this report, Appendix C describes the Laboratory’s technical

  3. Environmental surveillance at Los Alamos during 2008

    SciTech Connect

    Fuehne, David; Gallagher, Pat; Hjeresen, Denny; Isaacson, John; Johson, Scot; Morgan, Terry; Paulson, David; Rogers, David

    2009-09-30

    Environmental Surveillance at Los Alamos reports are prepared annually by the Los Alamos National Laboratory (the Laboratory) Environmental Programs Directorate, as required by US Department of Energy Order 450.1, General Environmental Protection Program, and US Department of Energy Order 231.1A, Environment, Safety, and Health Reporting. These annual reports summarize environmental data that are used to determine compliance with applicable federal, state, and local environmental laws and regulations, executive orders, and departmental policies. Additional data, beyond the minimum required, are also gathered and reported as part of the Laboratory’s efforts to ensure public safety and to monitor environmental quality at and near the Laboratory. Chapter 1 provides an overview of the Laboratory’s major environmental programs and explains the risks and the actions taken to reduce risks at the Laboratory from environmental legacies and waste management operations. Chapter 2 reports the Laboratory’s compliance status for 2007. Chapter 3 provides a summary of the maximum radiological dose the public and biota populations could have potentially received from Laboratory operations and discusses chemical exposures. The environmental surveillance and monitoring data are organized by environmental media (Chapter 4, air; Chapters 5 and 6, water and sediments; Chapter 7, soils; and Chapter 8, foodstuffs and biota) in a format to meet the needs of a general and scientific audience. Chapter 9 provides a summary of the status of environmental restoration work around LANL. A glossary and a list of acronyms and abbreviations are in the back of the report. Appendix A explains the standards for environmental contaminants, Appendix B explains the units of measurements used in this report, Appendix C describes the Laboratory’s technical areas and their associated programs, and Appendix D provides web links to more information.

  4. Environmental surveillance at Los Alamos during 2005

    SciTech Connect

    2006-09-30

    Environmental Surveillance at Los Alamos reports are prepared annually by the Los Alamos National Laboratory (LANL or the Laboratory) environmental organization, as required by US Department of Energy Order 5400.1, General Environmental Protection Program, and US Department of Energy Order 231.IA, Environment, Safety, and Health Reporting. These annual reports summarize environmental data that are used to determine compliance with applicable federal, state, and local environmental laws and regulations, executive orders, and departmental policies. Additional data, beyond the minimum required, are also gathered and reported as part of the Laboratory's efforts to ensure public safety and to monitor environmental quality at and near the Laboratory. Chapter 1 provides an overview of the Laboratory's major environmental programs. Chapter 2 reports the Laboratory's compliance status for 2005. Chapter 3 provides a summary of the maximum radiological dose the public and biota populations could have potentially received from Laboratory operations. The environmental surveillance and monitoring data are organized by environmental media (Chapter 4, Air; Chapters 5 and 6, Water and Sediments; Chapter 7, Soils; and Chapter 8, Foodstuffs and Biota) in a format to meet the needs of a general and scientific audience. Chapter 9, new for this year, provides a summary of the status of environmental restoration work around LANL. A glossary and a list ofacronyms and abbreviations are in the back of the report. Appendix A explains the standards for environmental contaminants, Appendix B explains the units of measurements used in this report, Appendix C describes the Laboratory's technical areas and their associated programs, and Appendix D provides web links to more information.

  5. Studies of shock induced flows in strengthless materials on Pegasus

    SciTech Connect

    Oro, D.M.; Fulton, R.D.; Stokes, J.; Guzik, J.A.; Adams, P.J.; Morgan, D.; Platts, D.; Obst, A.W.; Fell, M.

    1998-12-31

    Experiments on the Pegasus II pulsed power facility at Los Alamos are being conducted to study the evolution and flow of strengthless materials as a result of being shocked. Of particular interest is vorticity and mixing that is induced in the materials by a shock-wave passing through a non-uniform boundary. The experiments provide an important benchmark for hydrodynamic codes, and are a precursor to experiments planned on Atlas in which the materials will be pre-ionized before being shocked. For these experiments, flash radiography is used to image the position of the target boundaries at specific times. In these experiments 3 radiographs along target radii and 2 radiographs along the target axis are taken at independent times. The central cavity of the target is imaged with visible framing cameras. The Xe in this cavity radiates when shocked, and therefore the shape and timing of the shock front in the Xe can be determined from the images. Other diagnostics employed for this work include electric and magnetic field probes that are used to determine the current through the liner and when the liner impacts the target. Both the 1-d magnetohydrodynamics code RAVEN, and the 2-d/3-d adaptive grid eulerian code RAGE are used for pre-shot calculations. In this talk the authors will discuss the motivation for these experiments, compare calculations with radiographs and visible images and discuss future experiments on Pegasus and Atlas.

  6. Composite Liner, Multi-Megabar Shock Driver Development

    SciTech Connect

    Cochrane, J.C. Jr.; Bartsch, R.R.; Clark, D.A.; Morgan, D.V.; Anderson, W.E.; Lee, H.; Bowers, R.L.; Atchison, W.L.; Oona, H.; Stokes, J.L.; Veeser, L.R.; Broste, W.B.

    1998-10-18

    The multi-megabar shock driver development is a series of experiments in support of the Los Alamos High Energy Density Physics Experimental Program. Its purpose is to develop techniques to impact a uniform, stable, composite liner upon a high Z target to produce a multi-megabar shock for EOS studies. To date, experiments have been done on the Pegasus II capacitor bank with a current of {approximately}12MA driving the impactor liner. The driving field is {approximately}200 T at the target radius of 1cm. Data will be presented on the impactor liner. The driving field is {approximately}200 T at the target radius of 1 cm. Data will be presented on the stability and uniformity of the impactor liner when it impacts the target cylinder. Three experiments have been done with emphasis on liner development. Shock pressures greater than a megabar have been done with emphasis on liner development. Shock pressures greater than a megabar have been produced with an Al target cylinder. A Pt target cylinder should produce shock pressures in th e 5-megabar range.

  7. New radiative shocks experiment

    NASA Astrophysics Data System (ADS)

    Leygnac, S.; Bouquet, S.; Stehlé, C.; Benuzzi, A.; Boireau, J.-P.; Chièze, J.-P.; Grandjouan, N.; Huser, G.; Koenig, M.; Malka, V.; Merdji, H.; Michaut, C.; Thais, F.; Vinci, T.

    2002-06-01

    An experimental study of shocks with astrophysical relevance is performed with the high energy density laser of the LULI, at the Ecole Polytechnique. The peculiarity of these shocks is the strong coupling between radiation and hydrodynamics which leads to a structure governed by a radiative precursor. A new experiment has been performed this year where we have observed shocks identified as radiative shocks. We study them in various experimental configurations (several speeds and geometries of the medium where the shock propagates, allowing a quasi-planar or a quasi-spherical expansion). From the measurements it is possible to infer several features of the shock such as the speed, the electronic density, the geometrical shape and spectroscopic informations. The results will be studied with numerical simulations.

  8. Ion-chamber-based loss monitor system for the Los Alamos Meson Physics Facility

    SciTech Connect

    Plum, M.A.; Brown, D.; Browman, A.; Macek, R.J.

    1995-05-01

    A new loss monitor system has been designed and installed at the Los Alamos Meson Physics Facility (LAMPF). The detectors are ion chambers filled with N{sub 2} gas. The electronics modules have a threshold range of 1:100, and they can resolve changes in beam loss of about 2% of the threshold settings. They can generate a trip signal in 2 {mu}s if the beam loss is large enough; if the response time of the Fast Protect System is included the beam will be shut off in about 37 {mu}s.

  9. HYDROGEN DATA FROM LOS ALAMOS [LANL] & SAVANNAH RIVER [SRC] & ROCKY FLATS [RFE] [SEC 1 & 2

    SciTech Connect

    DAYLEY, L.

    2001-11-19

    A DOE letter dated August 14, 2001 requested that a detailed analysis of the expected probability of accumulation of significant quantities of hydrogen gas in unvented drums and a plan and schedule for venting drums be prepared and submitted. In response to the letter a document was prepared that included data of hydrogen concentrations in TRU waste drums. Data was collected from Savannah River Site, Los Alamos National Laboratory, and Rocky Flats Environmental Technology Site. These data were analyzed to provide the basis for evaluating the probability that significant quantities of hydrogen will accumulate in the unvented TRU drums stored at Hanford.

  10. Astrospheres and Stellar Bow shocks

    NASA Astrophysics Data System (ADS)

    Van Marle, Allard Jan

    2016-07-01

    As stars evolve, they deliver feedback to the surrounding medium in the form of stellar wind and radiation. These shape the surrounding matter, forming what is called an astrosphere, a sphere of influence in which the star dominates the morphology and composition of the surrounding medium. Astrospheres are fascinating objects. Because they are formed through the interaction between the stellar feedback and the interstellar gas, they can tell us a great deal about both. Furthermore, because they are shaped over time they provide us with a window into the past. This is of particular interest for the study of stellar evolution, because the astrosphere reflects changes in the properties of the stellar wind, which relate directly to the properties of the star. A special sub-class of astrospheres, the stellar bow shocks, occur when the progenitor star moves through the surrounding medium at supersonic speed. Because the properties of the bow shock relate directly to both the stellar wind and the interstellar medium, the shape and size of the bow shock can be used to determine these properties. Using state-of-the-art numerical codes, it is possible to simulate the interaction between the stellar wind and radiation and the interstellar medium. These results can then be compared to observations. They can also be used to predict the type of observations that are best suited to study these objects. In this fashion computational and observational astronomy can support each other in their efforts to gain a better understanding of stars and their environment.

  11. Weak shock reflection

    NASA Astrophysics Data System (ADS)

    Hunter, John K.; Brio, Moysey

    2000-05-01

    We present numerical solutions of a two-dimensional inviscid Burgers equation which provides an asymptotic description of the Mach reflection of weak shocks. In our numerical solutions, the incident, reflected, and Mach shocks meet at a triple point, and there is a supersonic patch behind the triple point, as proposed by Guderley for steady weak-shock reflection. A theoretical analysis indicates that there is an expansion fan at the triple point, in addition to the three shocks. The supersonic patch is extremely small, and this work is the first time it has been resolved.

  12. Anti-Shock Garment

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Ames Research Center developed a prototype pressure suit for hemophiliac children, based on research of astronauts' physiological responses in microgravity. Zoex Corporation picked up the design and patents and developed an anti-shock garment for paramedic use. Marketed by Dyna Med, the suit reverses the effect of shock on the body's blood distribution by applying counterpressure to the legs and abdomen, returning blood to vital organs and stabilizing body pressure until the patient reaches a hospital. The DMAST (Dyna Med Anti-Shock Trousers) employ lower pressure than other shock garments, and are non-inflatable.

  13. Developing a Radiative Shock Experiment Relevant to Astrophysics.

    PubMed

    Shigemori; Ditmire; Remington; Yanovsky; Ryutov; Estabrook; Edwards; MacKinnon; Rubenchik; Keilty; Liang

    2000-04-20

    We report on the initial results of experiments being developed on the Falcon laser to simulate radiative astrophysical shocks. Cylindrically diverging blast waves were produced in low-density ( approximately 1018 cm-3), high-Z gas by laser-irradiating Xe gas jets containing atomic clusters. The blast-wave trajectory was measured by Michelson interferometry. The velocity for the blast wave is slightly less than the adiabatic Sedov-Taylor prediction, and an ionization precursor is observed ahead of the shock front. This suggests energy loss through radiative cooling and reduced compression due to preheat deposited ahead of the shock, both consistent with one-dimensional radiation hydrodynamics simulations. PMID:10770714

  14. Two-temperature radiative shocks with electron thermal conduction

    NASA Technical Reports Server (NTRS)

    Borkowski, Kazimierz J.; Shull, J. Michael; Mckee, Christopher F.

    1989-01-01

    The influence of electron thermal conduction on radiative shock structure is studied for both one- and two-temperature plasmas. The dimensionless ratio of the conductive length to the cooling length determines whether or not conduction is important, and shock jump conditions with conduction are established for a collisionless shock front. Approximate solutions are obtained, with the assumptions that the ionization state of the gas is constant and the cooling rate is a function of temperature alone. In the absence of magnetic fields, these solutions indicate that conduction noticeably influences normal-abundance interstellar shocks with velocities 50-100 km/s and dramatically affects metal-dominated shocks over a wide range of shock velocities.

  15. Shock Waves in Dispersive Eulerian Fluids

    NASA Astrophysics Data System (ADS)

    Hoefer, Mark

    2013-11-01

    Shock waves in dispersive media with negligible dissipation are studied in the context of the compressible Euler equations with weak dispersion. Example fluids of this type include superfluids, shallow water flows, and ion-acoustic plasma. A characterization of one-dimensional dispersive shock waves (DSWs) will be presented. DSWs are sharply distinct from classical, dissipatively regularized shock waves both in terms of physical significance and mathematical description. Drawing on terminology from classical gas dynamics, jump conditions (shock loci and speeds) and admissibility criteria for the long time evolution of step-like initial data will be presented utilizing a nonlinear wave averaging technique. While entropy conditions determine admissible, dissipatively regularized shock waves, conservative, dispersive systems are time reversible and can exhibit positive or negative dispersion. The universal structure of weak shocks will be shown to depend solely upon the dispersion sign and pressure law. Large amplitude DSWs can exhibit novel effects such as cavitation and ``implosion'' yielding internal, multi-phase dynamics. Support from NSF DMS-1008973.

  16. Thermal Cycling Absorption Process (TCAP): Instrument and Simulation Development Status at Los Alamos National Laboratory

    SciTech Connect

    Arias, Angela A.; Schmierer, Eric N.; Gettemy, Donald; Howard, David W.; Wermer, Joseph R.; Tuggle, Dale G.

    2005-07-15

    The Thermal Cycling Absorption Process (TCAP) Project at Los Alamos National Laboratory has been a collaborative effort with Savannah River Site to demonstrate the Tube-in-Tube (TnT) column design and to improve TCAP science. TnT TCAP is an alternative design which uses a liquid to thermally cycle the metal hydride packed column. Inert gas displacement tests and deuterium pulse tests have been performed on the TnT TCAP column. The inert gas displacement tests are designed to measure plug flow in the column while the deuterium pulse tests determine the separation ability of the column. A residual gas analyzer measures the gases in the exit stream and the experimental results are compared with pulse test model results.

  17. Laboratory experiments on Radiative Shocks relevant to Stellar Accretion

    NASA Astrophysics Data System (ADS)

    Chaulagain, Uddhab

    2015-08-01

    Radiative shocks are strong shocks which are characterized by a plasma at high temperatures emitting an important fraction of its energy as radiation. Radiative shocks are found in many astrophysical systems, including stellar accretion shocks, supernovae remnants, jet driven shocks, etc. In the case of stellar accretion, matter is funneled into accretion columns by the stellar magnetic field, and falls at several hundreds km/s from the circumstellar envelope onto the stellar photosphere. This generates a strong radiative shock with x-ray spectral signatures that are a key ingredient to quantify the mass accretion rate. The physical structure and dynamics of such plasmas is complex, and experimental benchmarks are needed to provide a deeper understanding of the physics at play.Recently, radiative shocks have also been produced experimentally using high energy lasers. We discuss the results of an experiment performed on the Prague Asterix Laser System (PALS) facility. Shocks are generated by focusing the PALS Infrared laser beam on millimetre-scale targets filled with xenon gas at low pressure. The shock that is generated then propagates in the gas with a sufficiently high velocity such that the shock is in a radiative flux dominated regime. We will present the first instantaneous imaging of a radiative shock at 21.2 nm which is characterized by the presence of both the radiative precursor and the post shock structure. These results are complemented with time-and-space resolved XUV plasma self-emission measurements using fast diodes. Interpretation of the data, supported by numerical simulations using the 2-D radiative-hydrodynamics code ARWEN, will be presented showing the importance of radiative processes from atomic to larger scales.

  18. Magnetohydrodynamic Jump Conditions for Oblique Relativistic Shocks with Gyrotropic Pressure

    NASA Technical Reports Server (NTRS)

    Double, Glen P.; Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.

    2003-01-01

    Shock jump conditions, i.e., the specification of the downstream parameters of the gas in terms of the upstream parameters, are obtained for steady-state, plane shocks with oblique magnetic fields and arbitrary flow speeds. This is done by combining the continuity of particle number flux and the electromagnetic boundary conditions at the shock with the magnetohydrodynamic conservation laws derived from the stress-energy tensor. For ultrarelativistic and nonrelativistic shocks, the jump conditions may be solved analytically. For mildly relativistic shocks, analytic solutions are obtained for isotropic pressure using an approximation for the adiabatic index that is valid in high sonic Mach number cases. Examples assuming isotropic pressure illustrate how the shock compression ratio depends on the shock speed and obliquity. In the more general case of gyrotropic pressure, the jump conditions cannot be solved analytically with- out additional assumptions, and the effects of gyrotropic pressure are investigated by parameterizing the distribution of pressure parallel and perpendicular to the magnetic field. Our numerical solutions reveal that relatively small departures from isotropy (e.g., approximately 20%) produce significant changes in the shock compression ratio, r , at all shock Lorentz factors, including ultrarelativistic ones, where an analytic solution with gyrotropic pressure is obtained. In particular, either dynamically important fields or significant pressure anisotropies can incur marked departures from the canonical gas dynamic value of r = 3 for a shocked ultrarelativistic flow and this may impact models of particle acceleration in gamma-ray bursts and other environments where relativistic shocks are inferred. The jump conditions presented apply directly to test-particle acceleration, and will facilitate future self-consistent numerical modeling of particle acceleration at oblique, relativistic shocks; such models include the modification of the fluid

  19. On the boundary conditions on a shock wave for hypersonic flow around a descent vehicle

    NASA Astrophysics Data System (ADS)

    Golomazov, M. M.; Ivankov, A. A.

    2013-12-01

    Stationary hypersonic flow around a descent vehicle is examined by considering equilibrium and nonequilibrium reactions. We study how physical-chemical processes and shock wave conditions for gas species influence the shock-layer structure. It is shown that conservation conditions of species on the shock wave cause high-temperature and concentration gradients in the shock layer when we calculate spacecraft deceleration trajectory in the atmosphere at 75 km altitude.

  20. Shock compression experiments on Lithium Deuteride single crystals.

    SciTech Connect

    Knudson, Marcus D.; Desjarlais, Michael Paul; Lemke, Raymond W.

    2014-10-01

    S hock compression exper iments in the few hundred GPa (multi - Mabr) regime were performed on Lithium Deuteride (LiD) single crystals . This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17 - 32 km/s. Measurements included pressure, density, and temperature between %7E200 - 600 GPa along the Principal Hugoniot - the locus of end states achievable through compression by large amplitude shock waves - as well as pressure and density of re - shock states up to %7E900 GPa . The experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

  1. Modeling the shock initiation of PBX 9501 in ALE3D

    SciTech Connect

    Mace, Jonathan; Mas, Eric M; Leininger, Lara; Springer, H Keo

    2008-01-01

    The SMIS (Specific Munitions Impact Scenario) experimental series performed at Los Alamos National Laboratory has determined the 3-dimensional shock initiation behavior of the HMX based heterogeneous high explosive, PBX9501, which has a PMMA case and a steel impact cover. The SMIS real-world shot scenario creates a unique test-bed because many of the fragments arrive at the impact plate off-center and at an angle of impact. The goal of this model validation experiments is to demonstrate the predictive capability of the Tarver-Lee Ignition and Growth (I&G) reactive flow model in this fully 3-dimensional regime of Shock to Detonation Transition (SDT).

  2. Evidence for specularly reflected ions upstream from the quasi-parallel bow shock

    NASA Technical Reports Server (NTRS)

    Gosling, J. T.; Thomsen, M. F.; Bame, S. J.; Feldman, W. C.; Paschmann, G.; Sckopke, N.

    1982-01-01

    Ion velocity distributions in the form of bunches of gyrating particles traveling along helical paths have been observed moving sunward immediately upstream from quasi-parallel parts of the earth's bow shock using Los Alamos/Garching instruments on ISEE-1 and -2. These distributions have characteristics which indicate that they are produced by the nearly specular reflection at the shock of a portion of the incident solar wind ions. In particular, the guiding center motion and the gyrospeeds of the gyrating ions are quantitatively consistent with simple geometrical considerations for specular reflection. These considerations reveal that specularly reflected ions can escape upstream when the angle between the upstream magnetic field and the local shock normal is less than 45 deg but not when the angle is greater than 45 deg. These upstream gyrating ions are an important signature of one of the processes by which solar wind streaming energy is dissipated into other forms of energy at the shock.

  3. Shock wave interactions between slender bodies - Some aspects of three-dimensional shock wave diffraction

    NASA Astrophysics Data System (ADS)

    Hooseria, S. J.; Skews, B. W.

    2016-04-01

    A complex interference flowfield consisting of multiple shocks and expansion waves is produced when high-speed slender bodies are placed in close proximity. The disturbances originating from a generator body impinge onto the adjacent receiver body, modifying the local flow conditions over the receiver. This paper aims to uncover the basic gas dynamics produced by two closely spaced slender bodies in a supersonic freestream. Experiments and numerical simulations were used to interpret the flowfield, where good agreement between the predictions and measurements was observed. The numerical data were then used to characterise the attenuation associated with shock wave diffraction, which was found to be interdependent with the bow shock contact perimeter over the receiver bodies. Shock-induced boundary layer separation was observed over the conical and hemispherical receiver bodies. These strong viscous-shock interactions result in double-reflected, as well as double-diffracted shock wave geometries in the interference region, and the diffracting waves progress over the conical and hemispherical receivers' surfaces in "lambda" type configurations. This gives evidence that viscous effects can have a substantial influence on the local bow shock structure surrounding high-speed slender bodies in close proximity.

  4. Toxic Shock Syndrome: An Unusual Organism.

    PubMed

    Young, Katie; Luni, Faraz Khan; Yoon, Youngsook

    2016-07-01

    Streptococcal toxic shock syndrome is a rapidly fatal disease causing hypotension with multi organ dysfunction (MODS) early in the course of infection, which by definition is caused by Group A streptococcus (GAS). We describe a case of Toxic Shock like Syndrome (TSLS) in which the causative organism was not a GAS. A 71-year-old woman with hepatitis C and primary biliary cirrhosis had sudden onset of slurred speech and left arm and facial numbness. She had bilateral erythematous macular rash present on the flanks and legs. She was started on empiric antibiotics but her condition rapidly deteriorated 6 hours after admission. During this time, the development of multiple large reddish-pink areas of ecchymosis with bullae on her lower extremities, flanks, and groin were noted. She also developed multiorgan dysfunction (MODS) with renal dysfunction, coagulopathy and liver involvement. Patient expired before surgery could be performed and the time from presentation to the time of death was 16 hours. The blood and bullae fluid cultures grew Streptococcus dysgalactiae equisimilis. Streptococcus dysgalactiae equisimilis is a rare cause of TSLS which typically affects elderly or immunocompromised patients and only a few cases have been described in the literature. Our patient met criteria for TSLS which caused rapid shock and MODS. We review the literature of the cases describing the clinical characteristics of TSLS cause by non-GAS. Group G Streptococci is a rare but lethal cause of streptococcal toxic shock syndrome. PMID:27432040

  5. Compact proton spectrometers for measurements of shock

    SciTech Connect

    Mackinnon, A; Zylstra, A; Frenje, J A; Seguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M G; Casey, D T; Sinenian, N; Manuel, M; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G; Dewald, E; Doeppner, T; Edwards, M J; Glenzer, S H; Hicks, D; Landen, O L; London, R; Meezan, N B

    2012-05-02

    The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign (NIC) diagnostic. The WRF measures the spectrum of protons from D-{sup 3}He reactions in tuning-campaign implosions containing D and {sup 3}He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total {rho}R through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

  6. Explosive Flux Compression: 50 Years of Los Alamos Activities

    SciTech Connect

    Fowler, C.M.; Thomson, D.B.; Garn, W.B.

    1998-10-18

    Los Alamos flux compression activities are surveyed, mainly through references in view of space limitations. However, two plasma physics programs done with Sandia National Laboratory are discussed in more detail.

  7. Review of liquid metal heat pipe work at Los Alamos

    NASA Astrophysics Data System (ADS)

    Reid, Robert S.; Merrigan, Michael A.; Sena, J. Tom

    A survey of space-power related liquid metal heat pipe work at Los Alamos National Laboratory is presented. Heat pipe development at Los Alamos has been on-going since 1963. Heat pipes were initially developed for thermionic nuclear-electrical power production in space. Since then Los Alamos has developed liquid metal heat pipes for numerous applications related to high temperature systems in both the space and terrestrial environments. Some of these applications include thermionic electrical generators, thermoelectric energy conversion (both in-core and direct radiation), thermal energy storage, hypersonic vehicle leading edge cooling, and heat pipe vapor laser cells. Some of the work performed at Los Alamos has been documented in internal reports that are often little-known. A representative description and summary of progress in space-related liquid metal heat pipe technology is provided followed by a reference section citing sources where these works may be found.

  8. Review of liquid metal heat pipe work at Los Alamos

    SciTech Connect

    Reid, R.S.; Merrigan, M.A.; Sena, J.T. )

    1991-01-10

    A survey of space-power related liquid metal heat pipe work at Los Alamos National Laboratory is presented. Heat pipe development at Los Alamos has been on-going since 1963. Heat pipes were initially developed for thermionic nuclear-electrical power production in space. Since then Los Alamos has developed liquid metal heat pipes for numerous applications related to high temperature systems in both the space and terrestrial environments. Some of these applications include thermionic electrical generators, thermoelectric energy conversion (both in-core and direct radiation), thermal energy storage, hypersonic vehicle leading edge cooling, and heat pipe vapor laser cells. Some of the work performed at Los Alamos has been documented in internal reports that are often little-known. A representative description and summary of progress in space-related liquid metal heat pipe technology is provided followed by a reference section citing sources where these works may be found.

  9. Review of liquid metal heat pipe work at Los Alamos

    NASA Astrophysics Data System (ADS)

    Reid, Robert S.; Merrigan, Michael A.; Sena, J. Tom

    1991-01-01

    A survey of space-power related liquid metal heat pipe work at Los Alamos National Laboratory is presented. Heat pipe development at Los Alamos has been on-going since 1963. Heat pipes were initially developed for thermionic nuclear-electrical power production in space. Since then Los Alamos has developed liquid metal heat pipes for numerous applications related to high temperature systems in both the space and terrestrial environments. Some of these applications include thermionic electrical generators, thermoelectric energy conversion (both in-core and direct radiation), thermal energy storage, hypersonic vehicle leading edge cooling, and heat pipe vapor laser cells. Some of the work performed at Los Alamos has been documented in internal reports that are often little-known. A representative description and summary of progress in space-related liquid metal heat pipe technology is provided followed by a reference section citing sources where these works may be found.

  10. Review of liquid metal heat pipe work at Los Alamos

    NASA Astrophysics Data System (ADS)

    Reid, Robert S.; Merrigan, Michael A.; Sena, J. T.

    A survey of space-power related liquid metal heat pipe work at Los Alamos National Laboratory is presented. Heat pipe development at Los Alamos has been on-going since 1963. Heat pipes were initially developed for thermionic nuclear-electrical power production in space. Since then Los Alamos has developed liquid metal heat pipes for numerous applications related to high temperature systems in both the space and terrestrial environments. Some of these applications include thermionic electrical generators, thermoelectric energy conversion (both in-core and direct radiation), thermal energy storage, hypersonic vehicle leading edge cooling, and heat pipe vapor laser cells. Some of the work performed at Los Alamos has been documented in internal reports that are often little-known. A representative description and summary of progress in space-related liquid metal heat pipe technology is provided followed by reference section citing sources where these works may be found.

  11. Review of liquid metal heat pipe work at Los Alamos

    SciTech Connect

    Reid, R.S.; Merrigan, M.A.; Sena, J.T.

    1990-01-01

    A survey of space-power related liquid metal heat pipe work at Los Alamos National Laboratory is presented. Heat pipe development at Los Alamos has been on-going since 1963. Heat pipes were initially developed for thermionic nuclear-electrical power production in space. Since then Los Alamos has developed liquid metal heat pipes for numerous applications related to high temperature systems in both the space and terrestrial environments. Some of these applications include thermionic electrical generators, thermoelectric energy conversion (both in-core and direct radiation), thermal energy storage, hypersonic vehicle leading edge cooling, and heat pipe vapor laser cells. Some of the work performed at Los Alamos has been documented in internal reports that are often little-known. A representative description and summary of progress in space-related liquid metal heat pipe technology is provided followed by a reference section citing sources where these works may be found. 53 refs.

  12. Outflows, Jets and Shocks in the Orion Nebula

    NASA Technical Reports Server (NTRS)

    ODell, C. R.; Bally, John

    2000-01-01

    The rich young cluster of stars associated with the Orion Nebula provides a unique laboratory for the study of plasma phenomena. We see five types of flows and shocks. Photoablation outflow from the proplyds nearest theta (exp 1) Ori C form nearly stationary shocks with the high velocity wind from that star. Microjets, with scales of less than 10 (exp 4) AU, are seen around some 20 low mass stars. Isolated jets, with high velocities and scales of about, 104 AU, are less numerous but common. One also sees the shocks formed when these jets impinge on the ionized nebular gas and the neutral gas in the foreground lid. The final type of object is the stationary shock formed by the interaction from the stellar wind that arises during disk formation with the ambient, gas flowing away from the main body of the nebula.

  13. How Is Cardiogenic Shock Treated?

    MedlinePlus

    ... page from the NHLBI on Twitter. How Is Cardiogenic Shock Treated? Cardiogenic shock is life threatening and requires emergency medical treatment. ... arrive. The first goal of emergency treatment for cardiogenic shock is to improve the flow of blood and ...

  14. Environmental Surveillance at Los Alamos during 2007

    SciTech Connect

    2008-09-30

    Environmental Surveillance at Los Alamos reports are prepared annually by the Los Alamos National Laboratory (the Laboratory) Environmental Directorate, as required by US Department of Energy Order 450.1, General Environmental Protection Program, and US Department of Energy Order 231.1A, Environment, Safety, and Health Reporting. These annual reports summarize environmental data that are used to determine compliance with applicable federal, state, and local environmental laws and regulations, executive orders, and departmental policies. Additional data, beyond the minimum required, are also gathered and reported as part of the Laboratory’s efforts to ensure public safety and to monitor environmental quality at and near the Laboratory. Chapter 1 provides an overview of the Laboratory’s major environmental programs and explains the risks and the actions taken to reduce risks at the Laboratory from environmental legacies and waste management operations. Chapter 2 reports the Laboratory’s compliance status for 2007. Chapter 3 provides a summary of the maximum radiological dose the public and biota populations could have potentially received from Laboratory operations and discusses chemical exposures. The environmental surveillance and monitoring data are organized by environmental media (Chapter 4, air; Chapters 5 and 6, water and sediments; Chapter 7, soils; and Chapter 8, foodstuffs and biota) in a format to meet the needs of a general and scientific audience. Chapter 9 provides a summary of the status of environmental restoration work around LANL. A glossary and a list of acronyms and abbreviations are in the back of the report. Appendix A explains the standards for environmental contaminants, Appendix B explains the units of measurements used in this report, Appendix C describes the laboratory’s technical areas and their associated programs, and Appendix D provides web links to more information. In printed copies of this report or Executive Summary, we have

  15. Strategic defense initiatives at Los Alamos National Laboratory

    SciTech Connect

    Rockwood, S.D.

    1985-01-01

    This presentation reviews the Strategic Defense Initiative (SDI) programs at Los Alamos National Laboratory, noting especially the needs for and applications of optics and optical technologies. Table I lists the various activities at Los Alamos contributing to SDI programs. The principal, nonnuclear SDI programs are: (1) the free-electron laser, and (2) neutral particle beams. Both should be considered as potential long-range-kill systems, but still in the futuristic category.

  16. Shock Demagnetization of Pyrrhotite

    NASA Technical Reports Server (NTRS)

    Louzada, K. L.; Stewart, S. T.; Weiss, b. P.

    2005-01-01

    Maps of the remanent magnetic field of Mars show demagnetized zones within and around giant impact basins. It is likely that vast regions of the Martian crust were demagnetized due to a shock-induced phase change or magnetic transition of magnetic minerals in the crust. This hypothesis is supported by the fact that around the Hellas and Argyre basins, the edges of the unmagnetized zones roughly correspond with peak shock pressure contour lines of a few GPa. Although pyrrhotite is not a major carrier of magnetization in the Earth s crust, it is a common phase in Martian meteorites and may be an important carrier in the Martian crust. Understanding the effects of shock waves on magnetic minerals is critical for determining the origin of the demagnetized zones in impact basins and possibly for identifying the major magnetic carrier phases. Here we present the results of the first controlled shock demagnetization measurements on pyrrhotite. Previous experiments: Shock demagnetization

  17. Los Alamos low-level waste performance assessment status

    SciTech Connect

    Wenzel, W.J.; Purtymun, W.D.; Dewart, J.M.; Rodgers, J.E.

    1986-06-01

    This report reviews the documented Los Alamos studies done to assess the containment of buried hazardous wastes. Five sections logically present the environmental studies, operational source terms, transport pathways, environmental dosimetry, and computer model development and use. This review gives a general picture of the Los Alamos solid waste disposal and liquid effluent sites and is intended for technical readers with waste management and environmental science backgrounds but without a detailed familiarization with Los Alamos. The review begins with a wide perspective on environmental studies at Los Alamos. Hydrology, geology, and meteorology are described for the site and region. The ongoing Laboratory-wide environmental surveillance and waste management environmental studies are presented. The next section describes the waste disposal sites and summarizes the current source terms for these sites. Hazardous chemical wastes and liquid effluents are also addressed by describing the sites and canyons that are impacted. The review then focuses on the transport pathways addressed mainly in reports by Healy and Formerly Utilized Sites Remedial Action Program. Once the source terms and potential transport pathways are described, the dose assessment methods are addressed. Three major studies, the waste alternatives, Hansen and Rogers, and the Pantex Environmental Impact Statement, contributed to the current Los Alamos dose assessment methodology. Finally, the current Los Alamos groundwater, surface water, and environmental assessment models for these mesa top and canyon sites are described.

  18. The Los Alamos high-brightness photoinjector

    SciTech Connect

    O'Shea, P.G.

    1991-01-01

    For a number of years Los Alamos National Laboratory has been developing photocathode RF guns for high-brightness electron beam applications such as free-electron lasers (FELs). Previously thermionic high-voltage guns have been the source of choice for the electron accelerators used to drive FELs. The performance of such FELs is severely limited by the emittance growth produced by the subharmonic bunching process and also by the low peak current of the source. In a photoinjector, a laser driven photocathode is placed directly in a high-gradient RF accelerating cavity. A photocathode allows unsurpassed control over the current, and the spatial and temporal profile of the beam. In addition the electrodeless emission'' avoids many of the difficulties associated with multi-electrode guns, i.e. the electrons are accelerated very rapidly to relativistic energies, and there are no electrodes to distort the accelerating fields. For the past two years we have been integrating a photocathode into our existing FEL facility by replacing our thermionic gun and subharmonic bunchers with a high-gradient 1.3 GHz photoinjector. The photoinjector, which is approximately 0.6 m in length, produces 6 MeV, 300 A, 15 ps linac, and accelerated to a final energy of 40 MeV. We have recently begun lasing at wavelengths near 3 {mu}m. 16 refs., 2 figs., 5 tabs.

  19. NIST--Los Alamos racetrack microtron status

    SciTech Connect

    Wilson, M.A.; Ayres, R.L.; Cutler, R.I.; Debenham, P.H.; Lindstrom, E.R.; Mohr, D.L.; Penner, S.; Rose, J.E.; Young, L.M.

    1988-01-01

    The NIST-Los Alamos Racetrack Microtron (RTM) is designed to deliver a low-emittance electron beam of up to 0.5 mA cw over an energy range of 17 MeV to 185 MeV. Fed by a 5 MeV injector, the RTM contains two 180/degree/ end magnets that recirculate the beam up to 15 times through a 12 MeV RF linac. The linac, which operates in a standing-wave mode at 2380 MHz, has been tested to nearly full RF power. At present, the injector has undergone beam tests, and the beam transport system is complete through the 12 MeV linac. A temporary beam line has been installed at the exit of one end magnet to measure the beam energy, energy spread, and emittance after one pass through the accelerator. Preliminary results indicate that the accelerated beam energy spread and emittance are within design goals. 4 refs., 7 figs.

  20. Historic Manhattan Project Sites at Los Alamos

    SciTech Connect

    McGehee, Ellen

    2014-05-22

    The Manhattan Project laboratory constructed at Los Alamos, New Mexico, beginning in 1943, was intended from the start to be temporary and to go up with amazing speed. Because most of those WWII-era facilities were built with minimal materials and so quickly, much of the original infrastructure was torn down in the late '40s and early '50s and replaced by more permanent facilities. However, a few key facilities remained, and are being preserved and maintained for historic significance. Four such sites are visited briefly in this video, taking viewers to V-Site, the buildings where the first nuclear explosive device was pre-assembled in preparation for the Trinity Test in Southern New Mexico. Included is another WWII area, Gun Site. So named because it was the area where scientists and engineers tested the so-called "gun method" of assembling nuclear materials -- the fundamental design of the Little Boy weapon that was eventually dropped on Hiroshima. The video also goes to Pajarito Site, home of the "Slotin Building" and "Pond Cabin." The Slotin Building is the place where scientist Louis Slotin conducted a criticality experiment that went awry in early 1946, leading to his unfortunate death, and the Pond Cabin served the team of eminent scientist Emilio Segre who did early chemistry work on plutonium that ultimately led to the Fat Man weapon.

  1. Expanded recycling at Los Alamos National Laboratory

    SciTech Connect

    Betschart, J.F.; Malinauskas, L.; Burns, M.

    1996-07-01

    The Pollution Prevention Program Office has increased recycling activities, reuse, and options to reduce the solid waste streams through streamlining efforts that applied best management practices. The program has prioritized efforts based on volume and economic considerations and has greatly increased Los Alamos National Laboratory`s (LANL`s) recycle volumes. The Pollution Prevention Program established and chairs a Solid Waste Management Solutions Group to specifically address and solve problems in nonradioactive, Resource Conservation and Recovery Act (RCRA), state-regulated, and sanitary and industrial waste streams (henceforth referred to as sanitary waste in this paper). By identifying materials with recycling potential, identifying best management practices and pathways to return materials for reuse, and introducing the concept and practice of {open_quotes}asset management,{open_quotes} the Group will divert much of the current waste stream from disposal. This Group is developing procedures, agreements, and contracts to stage, collect, sort, segregate, transport and process materials, and is also garnering support for the program through the involvement of upper management, facility managers, and generators.

  2. Historic Manhattan Project Sites at Los Alamos

    ScienceCinema

    McGehee, Ellen

    2016-07-12

    The Manhattan Project laboratory constructed at Los Alamos, New Mexico, beginning in 1943, was intended from the start to be temporary and to go up with amazing speed. Because most of those WWII-era facilities were built with minimal materials and so quickly, much of the original infrastructure was torn down in the late '40s and early '50s and replaced by more permanent facilities. However, a few key facilities remained, and are being preserved and maintained for historic significance. Four such sites are visited briefly in this video, taking viewers to V-Site, the buildings where the first nuclear explosive device was pre-assembled in preparation for the Trinity Test in Southern New Mexico. Included is another WWII area, Gun Site. So named because it was the area where scientists and engineers tested the so-called "gun method" of assembling nuclear materials -- the fundamental design of the Little Boy weapon that was eventually dropped on Hiroshima. The video also goes to Pajarito Site, home of the "Slotin Building" and "Pond Cabin." The Slotin Building is the place where scientist Louis Slotin conducted a criticality experiment that went awry in early 1946, leading to his unfortunate death, and the Pond Cabin served the team of eminent scientist Emilio Segre who did early chemistry work on plutonium that ultimately led to the Fat Man weapon.

  3. Saving Water at Los Alamos National Laboratory

    SciTech Connect

    Erickson, Andy

    2015-03-16

    Los Alamos National Laboratory decreased its water usage by 26 percent in 2014, with about one-third of the reduction attributable to using reclaimed water to cool a supercomputing center. The Laboratory's goal during 2014 was to use only re-purposed water to support the mission at the Strategic Computing Complex. Using reclaimed water from the Sanitary Effluent Reclamation Facility, or SERF, substantially decreased water usage and supported the overall mission. SERF collects industrial wastewater and treats it for reuse. The reclamation facility contributed more than 27 million gallons of re-purposed water to the Laboratory's computing center, a secured supercomputing facility that supports the Laboratory’s national security mission and is one of the institution’s larger water users. In addition to the strategic water reuse program at SERF, the Laboratory reduced water use in 2014 by focusing conservation efforts on areas that use the most water, upgrading to water-conserving fixtures, and repairing leaks identified in a biennial survey.

  4. An analysis of combustion studies in shock expansion tunnels and reflected shock tunnels

    NASA Technical Reports Server (NTRS)

    Jachimowski, Casimir J.

    1992-01-01

    The effect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in high-speed flows for a simulated Mach 17 flight condition was investigated by analyzing the results of comparative combustion experiments performed in a reflected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes finite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and the presence of the nonequilibrium partially dissociated oxygen in the reflected shock tunnel enhances the combustion. Methods of compensating for the effect of dissociated oxygen are discussed.

  5. Investigations on detonation shock dynamics and related topics. Final report

    SciTech Connect

    Stewart, D.S.

    1993-11-01

    This document is a final report that summarizes the research findings and research activities supported by the subcontract DOE-LANL-9-XG8-3931P-1 between the University of Illinois (D. S. Stewart Principal Investigator) and the University of California (Los Alamos National Laboratory, M-Division). The main focus of the work has been on investigations of Detonation Shock Dynamics. A second emphasis has been on modeling compaction of energetic materials and deflagration to detonation in those materials. The work has led to a number of extensions of the theory of Detonation Shock Dynamics (DSD) and its application as an engineering design method for high explosive systems. The work also enhanced the hydrocode capabilities of researchers in M-Division by modifications to CAVEAT, an existing Los Alamos hydrocode. Linear stability studies of detonation flows were carried out for the purpose of code verification. This work also broadened the existing theory for detonation. The work in this contract has led to the development of one-phase models for dynamic compaction of porous energetic materials and laid the groundwork for subsequent studies. Some work that modeled the discrete heterogeneous behavior of propellant beds was also performed. The contract supported the efforts of D. S. Stewart and a Postdoctoral student H. I. Lee at the University of Illinois.

  6. Shock compression of low-density foams

    SciTech Connect

    Holmes, N.C.

    1993-07-01

    Shock compression of very low density micro-cellular materials allows entirely new regimes of hot fluid states to be investigated experimentally. Using a two-stage light-gas gun to generate strong shocks, temperatures of several eV are readily achieved at densities of roughly 0.5--1 g/cm{sup 3} in large, uniform volumes. The conditions in these hot, expanded fluids are readily found using the Hugoniot jump conditions. We will briefly describe the basic methodology for sample preparation and experimental measurement of shock velocities. We present data for several materials over a range of initial densities. This paper will explore the applications of these methods for investigations of equations of state and phase diagrams, spectroscopy, and plasma physics. Finally, we discus the need for future work on these and related low-density materials.

  7. Shock timing measurements in DT ice layers

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R. J.; Ross, J. S.; Lepape, S.; Ralph, J. E.; Berzak Hopkins, L. F.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

    2013-10-01

    Shock timing experiments on the National Ignition Facility (NIF) are routinely conducted using the keyhole target geometry, in which the strength and timing of multiple shocks are measured in a liquid-deuterium (D2) filled capsule interior. These targets have recently been modified to improve the surrogacy to ignition implosions by replacing the standard, continuous liquid D2 capsule fill with a deuterium-tritium (DT) ice layer with a central DT gas fill. These experiments remove any possible material surrogacy difference between D2 and DT as well as incorporating the physics of multiple shock release and recompression events from an ice layer of finite thickness, an effect that is absent in the liquid-filled targets. Experimental results and comparisons with numerical simulation are presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

  8. On the shape and motion of the Earth's bow shock

    NASA Astrophysics Data System (ADS)

    Meziane, K.; Alrefay, T. Y.; Hamza, A. M.

    2014-04-01

    Multipoint-measurements by the magnetic field Cluster-FGM (Flux Gate Magnetometer) are used to determine the local shock normal, and in turn allow the study of shock location shape and the velocity of the Earth's bow shock. The shock crossings cover orbits in which the spacecraft separation is of the order of ~600 km or less. A data selection of 133 bow shock crossings, ranging from quasi-steady perpendicular to moderately noisy oblique geometries, have been analyzed using a standard timing analysis. Prior to applying the timing technique, the magnetic field fluctuations, when present, are suppressed using low band-pass filtering. The present study contributes to similar studies conducted in the past and available in the literature through the inclusion of a larger data set. The shock standoff distance is determined conjointly with a paraboloid model and the results from a timing analysis. A statistical study reveals a standoff distance well in agreement with the standard gas dynamics model prediction for high Mach number MA. We have also found that for about half the crossings, the timing shock normals agree, within 11°, with a conic-based shock model. Our results strongly indicate that the motion of the shock is predominantly along the Sun-Earth direction; a departure from this direction is not related to the shock-crossing location. Shock velocities below ~80 km/s satisfactorily follow a nearly Gaussian distribution with zero mean and a standard deviation of ~42 km/s. Finally, we show that high speed motions are correlated with sharp increases in the solar wind upstream ram pressure, and are consistent with gas dynamics model predictions.

  9. Los Alamos National Laboratory W76 Pit Tube Lifetime Study

    SciTech Connect

    Abeln, Terri G.

    2012-04-25

    A metallurgical study was requested as part of the Los Alamos National Laboratory (LANL) W76-1 life-extension program (LEP) involving a lifetime analysis of type 304 stainless steel pit tubes subject to repeat bending loads during assembly and disassembly operations at BWXT/Pantex. This initial test phase was completed during the calendar years of 2004-2006 and the report not issued until additional recommended tests could be performed. These tests have not been funded to this date and therefore this report is considered final. Tubes were reportedly fabricated according to Rocky Flats specification P14548 - Seamless Type 304 VIM/VAR Stainless Steel Tubing. Tube diameter was specified as 0.125 inches and wall thickness as 0.028 inches. A heat treat condition is not specified and the hardness range specification can be characteristic of both 1/8 and 1/4 hard conditions. Properties of all tubes tested were within specification. Metallographic analysis could not conclusively determine a specified limit to number of bends allowable. A statistical analysis suggests a range of 5-7 bends with a 99.95% confidence limit. See the 'Statistical Analysis' section of this report. The initial phase of this study involved two separate sets of test specimens. The first group was part of an investigation originating in the ESA-GTS [now Gas Transfer Systems (W-7) Group]. After the bend cycle test parameters were chosen (all three required bends subjected to the same amount of bend cycles) and the tubes bent, the investigation was transferred to Terri Abeln (Metallurgical Science and Engineering) for analysis. Subsequently, another limited quantity of tubes became available for testing and were cycled with the same bending fixture, but with different test parameters determined by T. Abeln.

  10. Investigation of shock-shock interaction and Mach reflection in laterally colliding laser-blow-off plasmas

    SciTech Connect

    Kumar, Bhupesh; Singh, R. K.; Sengupta, Sudip; Kaw, P. K.; Kumar, Ajai

    2015-06-15

    Interactions of two Li plasma plumes and shock waves are investigated at various pressures (∼10{sup −5} to 3 mbar) in the argon gas ambient. Fast imaging and optical emission spectroscopy are used to study the plume dynamics and characteristic emission of plasmas. The plasma plumes are created in laser-blow-off geometry. The expansion of plasma plumes in the ambient gas leads to the formation of an interaction zone. The formation of interaction zone is dependent on the ambient pressure and below a certain pressure, no significant change is observed in the shape and size of the interaction plasma. In the higher pressure, formation of interaction zone and its shape are dependent on ambient pressure. Dynamics of seed plasmas and interaction zone are also affected by the shock-shock interactions. The shock-shock interaction depends on the angle of incidence (α) between two shock waves at the initial time of interaction but as the plumes expand, the shock-shock interaction does not follow α dependence.

  11. High-speed cameras at Los Alamos

    NASA Astrophysics Data System (ADS)

    Brixner, Berlyn

    1997-05-01

    In 1943, there was no camera with the microsecond resolution needed for research in Atomic Bomb development. We had the Mitchell camera (100 fps), the Fastax (10 000), the Marley (100 000), the drum streak (moving slit image) 10-5 s resolution, and electro-optical shutters for 10-6 s. Julian Mack invented a rotating-mirror camera for 10-7 s, which was in use by 1944. Small rotating mirror changes secured a resolution of 10-8 s. Photography of oscilloscope traces soon recorded 10-6 resolution, which was later improved to 10-8 s. Mack also invented two time resolving spectrographs for studying the radiation of the first atomic explosion. Much later, he made a large aperture spectrograph for shock wave spectra. An image dissecting drum camera running at 107 frames per second (fps) was used for studying high velocity jets. Brixner invented a simple streak camera which gave 10-8 s resolution. Using a moving film camera, an interferometer pressure gauge was developed for measuring shock-front pressures up to 100 000 psi. An existing Bowen 76-lens frame camera was speeded up by our turbine driven mirror to make 1 500 000 fps. Several streak cameras were made with writing arms from 4 1/2 to 40 in. and apertures from f/2.5 to f/20. We made framing cameras with top speeds of 50 000, 1 000 000, 3 500 000, and 14 000 000 fps.

  12. Echocardiography in shock management.

    PubMed

    McLean, Anthony S

    2016-01-01

    Echocardiography is pivotal in the diagnosis and management of the shocked patient. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied.In the acute situation a basic study often yields immediate results allowing for the initiation of therapy, while a follow-up advanced study brings the advantage of further refining the diagnosis and providing an in-depth hemodynamic assessment. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. A more comprehensive diagnosis can be achieved with advanced levels of competency, for which practice guidelines are also now available. Hemodynamic evaluation and ongoing monitoring are possible with advanced levels of competency, which includes the use of colour Doppler, spectral Doppler, and tissue Doppler imaging and occasionally the use of more recent technological advances such as 3D or speckled tracking.The four core types of shock-cardiogenic, hypovolemic, obstructive, and vasoplegic-can readily be identified by echocardiography. Even within each of the main headings contained in the shock classification, a variety of pathologies may be the cause and echocardiography will differentiate which of these is responsible. Increasingly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock or hypovolemia and ventricular outflow obstruction.The diagnostic benefit of echocardiography in the shocked patient is obvious. The increasing prevalence of critical care physicians experienced in advanced techniques means echocardiography often supplants the need for more invasive hemodynamic assessment and monitoring in shock. PMID:27543137

  13. Imploding conical shock waves

    NASA Astrophysics Data System (ADS)

    Paton, R. T.; Skews, B. W.; Rubidge, S.; Snow, J.

    2013-07-01

    The behaviour of conical shock waves imploding axisymmetrically was first studied numerically by Hornung (J Fluid Mech 409:1-12, 2000) and this prompted a limited experimental investigation into these complex flow patterns by Skews et al. (Shock Waves 11:323-326, 2002). Modification of the simulation boundary conditions, resulting in the loss of self-similarity, was necessary to image the flow experimentally. The current tests examine the temporal evolution of these flows utilising a converging conical gap of fixed width fed by a shock wave impinging at its entrance, supported by CFD simulations. The effects of gap thickness, angle and incident shock strength were investigated. The wave initially diffracts around the outer lip of the gap shedding a vortex which, for strong incident shock cases, can contain embedded shocks. The converging shock at exit reflects on the axis of symmetry with the reflected wave propagating outwards resulting in a triple point developing on the incident wave together with the associated shear layer. This axisymmetric shear layer rolls up into a mushroom-shaped toroidal vortex ring and forward-facing jet. For strong shocks, this deforms the Mach disk to the extent of forming a second triple point with the primary shock exhibiting a double bulge. Separate features resembling the Richtmeyer-Meshkov and Kelvin-Helmholtz instabilities were noted in some tests. Aside from the incident wave curvature, the reflection patterns demonstrated correspond well with the V- and DV-types identified by Hornung although type S was not clearly seen, possibly due to the occlusion of the reflection region by the outer diffraction vortex at these early times. Some additional computational work explicitly exploring the limits of the parameter space for such systems has demonstrated the existence of a possible further reflection type, called vN-type, which is similar to the von Neumann reflection for plane waves. It is recommended that the parameter space be

  14. Shocks near Jamming

    NASA Astrophysics Data System (ADS)

    Gómez, Leopoldo R.; Turner, Ari M.; van Hecke, Martin; Vitelli, Vincenzo

    2012-02-01

    Nonlinear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they jam, these fragile and disordered solids exhibit a vanishing rigidity and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are dynamically compressed and demonstrate that the elementary excitations are strongly nonlinear shocks, rather than ordinary phonons. We capture the full dependence of the shock speed on pressure and impact intensity by a surprisingly simple analytical model.

  15. Anthrax-associated shock.

    PubMed

    Goldman, David L; Casadevall, Arturo

    2008-01-01

    Recent events have brought attention to the potential of Bacillus anthracis as an agent of bioterrorism. The shock like state of anthrax is invariably associated with high mortality, despite anti-microbial and supportive therapy. Multi-system dysfunction is typical, including: enhanced vascular permeability, hemorrhage and inflammation. Important questions concerning the pathophysiology of anthrax-associated shock remain unanswered, including the effects of B. anthracis infection on cardiac function. This review discusses the current state of knowledge regarding the pathophysiology of anthrax-associated shock. PMID:18508494

  16. PHOSPHORUS CHEMISTRY IN THE SHOCKED REGION L1157 B1

    SciTech Connect

    Aota, T.; Aikawa, Y.

    2012-12-10

    We study the evolution of phosphorus-bearing species in one-dimensional C-shock models. We find that the abundances of P-bearing species depend sensitively on the elemental abundance of P in the gas phase and on the abundance of N atoms in the pre-shock gas. The observed abundance of PN and the non-detection of PO toward L1157 B1 are reproduced in C-shock models with shock velocity v = 20 km s{sup -1} and pre-shock density n(H{sub 2}) 10{sup 4}-10{sup 5} cm{sup -3}, if the elemental abundance of P in the gas phase is {approx}10{sup -9} and the N-atom abundance is n(N)/n{sub H} {approx}10{sup -5} in the pre-shock gas. We also find that P-chemistry is sensitive to O- and N-chemistry because N atoms are destroyed mainly by OH and NO. We identify the reactions of O-bearing and N-bearing species that significantly affect P-chemistry.

  17. Shock characterization of quartz phenolic composite

    SciTech Connect

    Weirick, L.J.; Chhabildas, L.C.

    1994-03-01

    Goal was to obtain dynamic mechanical property data on a quartz phenolic (abbreviated QP) composite. Shock loading and shock release measurements have been conducted using impact techniques utilizing both a light-gas gun and a powder gun at impact pressures up to 20 GPa. The primary diagnostic tool used was a velocity interferometer. The data analysis includes Hugoniot measurements to give both pressure-particle velocity and shock velocity-particle velocity relationships; spall measurements to determine the fracture stress at which the material spells; and attenuation measurements to determine the shock attenuation with material thickness. The QP Hugoniot relationship was found to be significantly different than that of a phenolic without a filler material indicating that the impedance of the QP used in this investigation was higher. The spall strength was measured to be {approximately}0.075 GPa, similar to nonfilled phenolic, which indicated that the presence of quartz fibers was not contributing to the fracture strength. The material was found to attenuate an imposed shock of approximately 6.3 GPa pressure and 0.18 {mu}s to 50% of the initial impact value after a propagation distance of 7mm.

  18. Recent UCN source developments at Los Alamos

    SciTech Connect

    Seestrom, S.J.; Anaya, J.M.; Bowles, T.J.

    1998-12-01

    The most intense sources of ultra cold neutrons (UCN) have bee built at reactors where the high average thermal neutron flux can overcome the low UCN production rate to achieve usable densities of UCN. At spallation neutron sources the average flux available is much lower than at a reactor, though the peak flux can be comparable or higher. The authors have built a UCN source that attempts to take advantage of the high peak flux available at the short pulse spallation neutron source at the Los Alamos Neutron Science Center (LANSCE) to generate a useful number of UCN. In the source UCN are produced by Doppler-shifted Bragg scattering of neutrons to convert 400-m/s neutrons down into the UCN regime. This source was initially tested in 1996 and various improvements were made based on the results of the 1996 running. These improvements were implemented and tested in 1997. In sections 2 and 3 they discuss the improvements that have been made and the resulting source performance. Recently an even more interesting concept was put forward by Serebrov et al. This involves combining a solid Deuterium UCN source, previously studied by Serebrov et al., with a pulsed spallation source to achieve world record UCN densities. They have initiated a program of calculations and measurements aimed at verifying the solid Deuterium UCN source concept. The approach has been to develop an analytical capability, combine with Monte Carlo calculations of neutron production, and perform benchmark experiments to verify the validity of the calculations. Based on the calculations and measurements they plan to test a modified version of the Serebrov UCN factory. They estimate that they could produce over 1,000 UCN/cc in a 15 liter volume, using 1 {micro}amp of 800 MeV protons for two seconds every 500 seconds. They will discuss the result UCN production measurements in section 4.

  19. Waste characterization at Los Alamos National Laboratory

    SciTech Connect

    Corpion, J.C.; Grieggs, A.R.

    1991-01-01

    Most industries generate limited types of solid wastes of a result of their manufacturing processes. The Los Alamos National Laboratory (LANL), a research and development facility, generates a large variety of solid wastes, some exotic. Over 50,000 distinct waste streams are currently generated in the 43 square mile area defining LANL. These wastes include refuse, medical, infectious, hazardous, radioactive, and mixed wastes. LANL is subject to federal and State oversight on matters concerning management of solid wastes. In order to assure regulatory agencies such as the New Mexico Environment Department (NMED) and the US Environmental Protection Agency (EPA) that the Laboratory is properly managing and disposing all solid wastes. LANL has undertaken an extensive waste characterization program to identify sources and ultimate disposition of all solid wastes. Given the number of solid waste streams expected, LANL has taken a two-pronged approach to characterizing wastes: (a) physical identification of all sources of solid wastes including interviews with waste generators; and (b) characterization of wastes from the point of generation. The former approach consists of canvassing all structures within the LANL complex, interviewing waste generators, and identifying sources of waste generation. Data gathered by these interviews are compiled in a database in order to identify the types and rates of waste generation and correct mismanagement of wastes identified during the interviews. The latter approach consists of characterizing all solid wastes which are controlled administratively or subject to stricter controls than municipal solid wastes (i.e., infectious, hazardous, radioactive, and mixed wastes). This characterization forms the basis by which LANL will manage solid waste in accordance to NMED/EPA regulations and US Department of Energy Orders. 8 refs., 3 figs.

  20. Distribution of Electric Field across Shock Structure Propagating through a DC Glow Discharge

    NASA Astrophysics Data System (ADS)

    Popovic, S.; Vuskovic, L.

    1998-10-01

    A number of experiments confirmed the existence of double electric layer (DEL) due to ambipolar diffusion of electrons and ions in the shock front propagating through partially ionized gas. It was used to visualize shock shapes with an electric discharge transverse to the flow. Charge separation generated local electric field that interacted with the electric field of the discharge, to slow down the electron drift, and resulted in a decrease of luminosity along shock front. DEL effect was used to demonstrate a "bow shock generator." Voltage difference between upstream and downstream region of partially ionized gas depended on shock strength manifested in electron temperature and number density gradients. These two gradients did not necessarily coincide, and more than one DEL could be associated with the shock. Based on these facts, we derived reduced electric field distributions in a planar and oblique shock structure. We also determined the parameters and stability criteria for the regions of enhanced degree of ionization associated with DEL.

  1. Enhancement of airborne shock wave by laser-induced breakdown of liquid column in laser shock cleaning

    SciTech Connect

    Jang, Deoksuk; Kim, Dongsik; Park, Jin-Goo

    2011-04-01

    In laser shock cleaning (LSC), the shock wave is generated by laser-induced breakdown of the ambient gas. The shock wave intensity has thus been a factor limiting the performance of the LSC process. In this work, a novel method of amplifying a laser-induced plasma-generated shock wave by the breakdown of a liquid column is proposed and analyzed. When the laser beam is focused on a microscale liquid column, a shock wave having a significantly amplified intensity compared to that generated by air breakdown alone can be generated in air. Therefore, substantially amplified cleaning force can be obtained. The dynamics of a shock wave induced by a Q-switched Nd:YAG laser was analyzed by laser flash shadowgraphy. The peak pressure of the laser-induced shock wave was approximately two times greater than that of air breakdown at the same laser fluence. The proposed method of shock wave generation is expected to be useful in various applications of laser shock processing, including surface cleaning.

  2. Testing bow shock models

    NASA Astrophysics Data System (ADS)

    Alrefay, Thamer; Meziane, Karim; Hamza, A. M.

    2016-07-01

    Space plasmas studies of bow shock dynamics, given the fundamental transport role and impact natural transition boundaries, have continued to attract much interest. With the overwhelming availability of data collected by various space science missions, several empirical models have been put forward to account for the location of the Earth's bow shock. Various solar wind and IMF measured parameters are used to constrain the proposed models published in the literature. For each of these empirical models, the bow shock nose velocity, at the standoff distance, is computed; each of these velocities is then compared with the observed shock speed as determined from a multipoint measurement provided by the Cluster quartet. The present study reveals to what extent the model parameters used are significant and determinant, and suggests that some empirical models are more accurate than others are.

  3. Counseling For Future Shock

    ERIC Educational Resources Information Center

    Morgan, Lewis B.

    1974-01-01

    In this article the author looks at some of the searing prophecies made by Alvin Toffler in his book Future Shock and relates them to the world of the professional counselor and the clientele the counselor attempts to serve. (Author)

  4. Collisionless parallel shocks

    NASA Technical Reports Server (NTRS)

    Khabibrakhmanov, I. KH.; Galeev, A. A.; Galinskii, V. L.

    1993-01-01

    Consideration is given to a collisionless parallel shock based on solitary-type solutions of the modified derivative nonlinear Schroedinger equation (MDNLS) for parallel Alfven waves. The standard derivative nonlinear Schroedinger equation is generalized in order to include the possible anisotropy of the plasma distribution and higher-order Korteweg-de Vies-type dispersion. Stationary solutions of MDNLS are discussed. The anisotropic nature of 'adiabatic' reflections leads to the asymmetric particle distribution in the upstream as well as in the downstream regions of the shock. As a result, nonzero heat flux appears near the front of the shock. It is shown that this causes the stochastic behavior of the nonlinear waves, which can significantly contribute to the shock thermalization.

  5. A Shocking Surprise in Stephan's Quintet

    NASA Technical Reports Server (NTRS)

    2006-01-01

    This false-color composite image of the Stephan's Quintet galaxy cluster clearly shows one of the largest shock waves ever seen (green arc). The wave was produced by one galaxy falling toward another at speeds of more than one million miles per hour. The image is made up of data from NASA's Spitzer Space Telescope and a ground-based telescope in Spain.

    Four of the five galaxies in this picture are involved in a violent collision, which has already stripped most of the hydrogen gas from the interiors of the galaxies. The centers of the galaxies appear as bright yellow-pink knots inside a blue haze of stars, and the galaxy producing all the turmoil, NGC7318b, is the left of two small bright regions in the middle right of the image. One galaxy, the large spiral at the bottom left of the image, is a foreground object and is not associated with the cluster.

    The titanic shock wave, larger than our own Milky Way galaxy, was detected by the ground-based telescope using visible-light wavelengths. It consists of hot hydrogen gas. As NGC7318b collides with gas spread throughout the cluster, atoms of hydrogen are heated in the shock wave, producing the green glow.

    Spitzer pointed its infrared spectrograph at the peak of this shock wave (middle of green glow) to learn more about its inner workings. This instrument breaks light apart into its basic components. Data from the instrument are referred to as spectra and are displayed as curving lines that indicate the amount of light coming at each specific wavelength.

    The Spitzer spectrum showed a strong infrared signature for incredibly turbulent gas made up of hydrogen molecules. This gas is caused when atoms of hydrogen rapidly pair-up to form molecules in the wake of the shock wave. Molecular hydrogen, unlike atomic hydrogen, gives off most of its energy through vibrations that emit in the infrared.

    This highly disturbed gas is the most turbulent molecular hydrogen ever seen. Astronomers were

  6. Attosecond shock waves.

    PubMed

    Zhokhov, P A; Zheltikov, A M

    2013-05-01

    Shock-wave formation is a generic scenario of wave dynamics known in nonlinear acoustics, fluid dynamics, astrophysics, seismology, and detonation physics. Here, we show that, in nonlinear optics, remarkably short, attosecond shock transients can be generated through a strongly coupled spatial and temporal dynamics of ultrashort light pulses, suggesting a pulse self-compression scenario whereby multigigawatt attosecond optical waveforms can be synthesized. PMID:23683197

  7. Shock enhancement and control of hypersonic mixing and combustion

    NASA Technical Reports Server (NTRS)

    Marble, Frank E.; Zukoski, Edward E.; Jacobs, Jeffrey; Hendricks, Gavin; Waitz, Ian

    1990-01-01

    Experimental and computational analyses of the possibility that shock-enhanced mixing can substantially increase the rate of mixing between coflowing streams of hydrogen and air are discussed. Numerical computations indicate that the steady interaction between a weak shock in air with a coflowing hydrogen jet can be approximated by the two-dimensional time-dependent interaction between a weak shock and an initially circular region filled with hydrogen imbedded in air. Experimental results obtained in a shock tube and contoured wall injector are presented. It is shown that the shock impinging process causes the light gas cylinder to split into two parts; one of these mixes rapidly with air and the other forms a stably stratified vortex pair which mixes more slowly. The geometry of the flow field and the mixing process and scaling parameters are assessed.

  8. The elastic-plastic behaviour of foam under shock loading

    NASA Astrophysics Data System (ADS)

    Petel, O. E.; Ouellet, S.; Higgins, A. J.; Frost, D. L.

    2013-02-01

    An experimental investigation of the elastic-plastic nature of shock wave propagation in foams was undertaken. The study involved experimental blast wave and shock tube loading of three foams, two polyurethane open-cell foams and a low-density polyethylene closed-cell foam. Evidence of precursor waves was observed in all three foam samples under various compressive wave loadings. Experiments with an impermeable membrane are used to determine if the precursor wave in an open-cell foam is a result of gas filtration or an elastic response of the foam. The differences between quasi-static and shock compression of foams is discussed in terms of their compressive strain histories and the implications for the energy absorption capacity of foam in both loading scenarios. Through a comparison of shock tube and blast wave loading techniques, suggestions are made concerning the accurate measurements of the principal shock Hugoniot in foams.

  9. The Supernova Shock

    NASA Astrophysics Data System (ADS)

    Bethe, Hans A.

    1995-08-01

    Vigorous convection is the key to the supernova mechanism. An analytic theory is presented which parallels the computations of Herant et al. Energy is delivered by neutrinos to the convecting medium. The most important quantity is p1r3, where P1 is the density outside the shock. This can be obtained from the computations of Wilson et al., since it is not affected by the convection behind the shock. It is closely related to Mdot, the rate at which matter falls in toward the center. The outgoing shock is dominated by the Hugoniot equation; the shock cannot move out until its energy is of the order of 1 foe (= 1051 ergs). Once it moves, its velocity and energy are calculated as functions of its radius. Nucleosynthesis gives an appreciable contribution to the energy. A substantial fraction of the energy is initially stored as nuclear dissociation energy, and then released as the shock moves out. This energy cannot at present be calculated from first principles, but it can be deduced from the observed energy of SN 1987A of 1.4±0.4 foe. From the result it is shown that about one-half of the infalling material goes into the shock and one-half accretes to the neutron star.

  10. AOTV bow shock location

    NASA Technical Reports Server (NTRS)

    Desautel, D.

    1985-01-01

    Hypersonic bow-shock location and geometry are of central importance to the aerodynamics and aerothermodynamics of aeroassisted orbital transfer vehicles (AOTVs), but they are difficult to predict for a given vehicle configuration. This paper reports experimental measurements of shock standoff distance for the 70 deg cone AOTV configuration in shock-tunnel-test flows at Mach numbers of 3.8 to 7.9 and for angles of attack from 0 deg to 20 deg. The controlling parameter for hypersonic bow-shock standoff distance (for a given forebody shape) is the mean normal-shock density ratio. Values for this parameter in the tests reported are in the same range as those of the drag-brake AOTV perigee regime. Results for standoff distance are compared with those previously reported in the literature for this AOTV configuration. It is concluded that the AOTV shock standoff distance for the conical configuration, based on frustrum (base) radius, is equivalent to that of a sphere with a radius about 35 percent greater than that of the cone; the distance is, therefore, much less than reported in previous studies. Some reasons for the discrepancies between the present and previous are advanced. The smaller standoff distance determined here implies there will be less radiative heat transfer than was previously expected.

  11. Nonequilibrium ionization phenomena behind shock waves

    SciTech Connect

    Panesi, Marco; Magin, Thierry; Huo, Winifred

    2011-05-20

    An accurate investigation of the behavior of electronically excited states of atoms and molecules in the post shock relaxation zone of a trajectory point of the FIRE II flight experiment is carried out by means of a one-dimensional flow solver coupled to a collisional-radiative model. In the rapidly ionizing regime behind a strong shock wave, the high lying bound electronic states of atoms are depleted. This leads the electronic energy level populations of atoms to depart from Boltzmann distributions which strongly affects the non-equilibrium ionization process as well as the radiative signature. The importance of correct modeling of the interaction of radiation and matter is discussed showing a strong influence on the physico-chemical properties of the gas. The paper clearly puts forward the shortcomings of the simplified approach often used in literature which strongly relies on the escape factors to characterize the optical thickness of the gas.

  12. Electron Acceleration in Shock-Shock Interaction: Simulations and Observations

    NASA Astrophysics Data System (ADS)

    Nakanotani, M.; Matsukiyo, S.; Mazelle, C. X.; Hada, T.

    2015-12-01

    Collisionless shock waves play a crucial role in producing high energy particles (cosmic rays) in space. While most of the past studies about particle acceleration assume the presence of a single shock, in space two shocks frequently come close to or even collide with each other. Hietala et al. [2011] observed the collision of an interplanetary shock and the earth's bow shock and the associated acceleration of energetic ions. The kinetic natures of a shock-shock collision has not been well understood. Only the work done by using hybrid simulation was reported by Cargill et al. [1986], in which they focus on a collision of two supercritical shocks and the resultant ion acceleration. We expect similarly that electron acceleration can also occur in shock-shock collision. To investigate the electron acceleration process in a shock-shock collision, we perform one-dimensional full particle-in-cell (PIC) simulations. In the simulation energetic electrons are observed between the two approaching shocks before colliding. These energetic electrons are efficiently accelerated through multiple reflections at the two shocks (Fermi acceleration). The reflected electrons create a temperature anisotropy and excite large amplitude waves upstream via the electron fire hose instability. The large amplitude waves can scatter the energetic electrons in pitch angle so that some of them gain large pitch angles and are easily reflected when they encounter the shocks subsequently. The reflected electrons can sustain, or probably even strengthen, them. We further discuss observational results of an interaction of interplanetary shocks and the earth's bow shock by examining mainly Cluster data. We focus on whether or not electrons are accelerated in the shock-shock interaction.

  13. Measurement of unsaturated hydraulic conductivity in the Bandelier Tuff at Los Alamos

    SciTech Connect

    Conca, J.; Mockler, T.J.

    1995-04-01

    Hydraulic conductivities, K, were experimentally determined as a function of volumetric water content, {theta}, in Bandelier Tuff cores from Los Alamos, New Mexico. These data were used to determine the feasibility of applying a new unsaturated flow technology (UFA{trademark}) to further hydrologic studies of tuffaceous rocks at Los Alamos. The K({theta}) relationships for eight cores of Bandelier Tuff from boreholes AAA and AAB were measured using the UFA and, together with their in situ water contents, were used to determine transient water flux into these samples at the time of sampling. If the system is at steady-state, then these flux values correspond to the recharge through those points, a situation often encountered in semi-arid to arid regions such as Los Alamos and other sites in the western United States. Samples AAA 9956, AAB 0011, AAB 0012 and AAB 0040 exhibited fluxes of 6 x 10{sup -8} cm/s, 4.8 x 10{sup -7} cm/s, 2.8 x 10{sup -7} cm/s and 2.4 x 10{sup -8} cm/s, respectively, indicating significant flux. Samples AAB 0063, AAB 0065, AAB 0072 and AAB 0081 had very low water contents suggesting fluxes less than 10{sup -10} cm/s, and appear to be close to their residual water contents. Assuming that the samples AAB 0063, AAB 0065, AAB 0072 and AAB 0081 were not accidentally dried out during handling, these results imply that these samples have zero recharge and that redistribution of moisture at these horizons is controlled more by vapor diffusion than by advection. The vapor diffusivities in these cores can be determined using the new UFA gas permeameter. Samples AAA 9956, AAB 0011, AAB 0012 and AAB 0040 appear to be controlled by advection.

  14. LOW AMPLITUDE SINGLE AND MULTIPLE SHOCK INITIATION EXPERIMENTS AND MODELING OF LX-04

    SciTech Connect

    Vandersall, K S; Tarver, C M; Garcia, F; Chidester, S; Urtiew, P A; Forbes, J W

    2006-06-27

    Shock initiation experiments were performed on the plastic bonded explosive (PBX) LX-04 (85% HMX, 15% Viton binder) using single and multiple low amplitude shocks to obtain pressure history data for use in Ignition and Growth reactive flow modeling parameterization. A 100 mm diameter propellant driven gas gun was utilized to initiate the LX-04 explosive charges containing manganin piezoresistive pressure gauge packages placed between explosive discs. In the single shock experiments, the run distances to detonation at three shock pressures showed agreement with previously published data above 3 GPa. Even longer run distances to detonation were measured using 80 mm long by 145 mm diameter LX-04 charges impacted by low velocity projectiles from a 155 mm diameter gun. The minimum shock pressure required to cause low levels of exothermic reaction were determined for these large LX-04 charge dimensions. Multiple shocks were generated as double shocks by using a flyer plate with two materials and as reflected shocks by placing a high impedance material at the rear of the explosive charge. In both cases, the first shock pressure was not high enough to cause detonation of LX-04, and the second shock pressure, which would have been sufficient to cause detonation if generated by a single shock, failed to cause detonation. Thus LX-04 exhibited shock desensitization over a range of 0.6 to 1.4 GPa. The higher shock pressure LX-04 model was extended to accurately simulate these lower pressure and multiple shock gauge records. The shock desensitization effects observed with multiple shock compressions were partially accounted for in the model by using a critical compression corresponding to a shock pressure of 1.2 GPa. This shock desensitization effect occurs at higher pressures than those of other HMX-based PBX's containing higher HMX percentages.

  15. Shock compression profiles in ceramics

    SciTech Connect

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  16. The Interaction of a Reflected Shock Wave with the Boundary Layer in a Shock Tube

    NASA Technical Reports Server (NTRS)

    Mark, Herman

    1958-01-01

    Ideally, the reflection of a shock from the closed end of a shock tube provides, for laboratory study, a quantity of stationary gas at extremely high temperature. Because of the action of viscosity, however, the flow in the real case is not one-dimensional, and a boundary layer grows in the fluid following the initial shock wave. In this paper simplifying assumptions are made to allow an analysis of the interaction of the shock reflected from the closed end with the boundary layer of the initial shock afterflow. The analysis predicts that interactions of several different types will exist in different ranges of initial shock Mach number. It is shown that the cooling effect of the wall on the afterflow boundary layer accounts for the change in interaction type. An experiment is carried out which verifies the existence of the several interaction regions and shows that they are satisfactorily predicted by the theory. Along with these results, sufficient information is obtained from the experiments to make possible a model for the interaction in the most complicated case. This model is further verified by measurements made during the experiment. The case of interaction with a turbulent boundary layer is also considered. Identifying the type of interaction with the state of turbulence of the interacting boundary layer allows for an estimate of the state of turbulence of the boundary layer based on an experimental investigation of the type of interaction. A method is proposed whereby the effect of the boundary-layer interaction on the strength of the reflected shock may be calculated. The calculation indicates that the reflected shock is rapidly attenuated for a short distance after reflection, and this result compares favorably with available experimental results.

  17. Outlook for future high-pressure shock experiments on minerals

    NASA Astrophysics Data System (ADS)

    Ahrens, T. J.; Asimow, P. D.; Luo, S.; Long, M.; Gelle, E.; Sun, D.

    2006-12-01

    Recent technical progress in several areas related to shock wave experiments in geophysics is enabling a number of new classes of investigation. We will review three particular areas that promise to yield abundant high-quality data in the near future. The timing precision attainable with a simple and effective two-magnet projectile detector has turned out to be unexpectedly good. It enables shock experiments on targets pre-heated to temperatures 1400-1700 degrees C without the use of contact trigger pins at light gas gun shock pressures. The use of in-flight precision projectile detection and realtime computing yields calculated trigger signals to that are accurate to +/-100 ns and allow the highest resolution streak recordings. This development will enable much higher throughput of pre- heated experiments on silicate liquids, minerals, and metals in our lab. The method of data reduction for multichannel pyrometry recordings of shock temperature has been dramatically improved. The measurement of sample absorbance as outlined by Boslough (1989) permits direct calculation of emissivities vs. wavelength for semi-absorbent minerals and obviates previously required assumptions regarding grey-body radiation. As a result data uncertainties have decreased from typically +/- 500 K to +/-100 K for states in the ~5000 K range. This development should enable a new generation of high- precision shock temperature determinations, as well as retrospective re-analysis of archived data. Recently the superheating method of detection of shock melting discovered at Caltech has been extended to the sub-nanosecond shock state region using the laser-driven shock apparatus and appears to give radiance histories which are in complete agreement with much longer duration light gas gun experiments. The short duration laser-driven shock experiments have great possibility to study the details of shock-induced phase transformations and melting in the future.

  18. Far-Infrared Water Emissions from Magnetohydrodynamic Shock Waves

    NASA Technical Reports Server (NTRS)

    Kaufman, Michael J.; Neufeld, David A.

    1996-01-01

    Nondissociative, magnetohydrodynamic, C-type shock waves are expected to be a prodigious source of far-infrared water emissions in dense interstellar regions. We have constructed a model to calculate the farinfrared H20 line spectra that emerge from such shocks. Using the best estimates currently available for the radiative cooling rate and the degree of ion-neutral coupling within the shocked gas, we modeled the temperature structure of MHD shocks using standard methods in which the charged and neutral particles are treated separately as two weakly coupled, interpenetrating fluids. Then we solved the equations of statistical equilibrium to find the populations of the lowest 179 and 170 rotational states of ortho- and para-H2O We have completed an extensive parameter study to determine the emergent H2O line luminosities as a function of preshock density in the range n(H2) equals 10(exp 4) - 10(sup 6.5)/cc and shock velocity in the range upsilon(sub s) = 5 - 40 km/ s. We find that numerous rotational transitions of water are potentially observable using the Infrared Space Observatory and the Submillimeter Wave Astronomy Satellite and may be used as diagnostics of the shocked gas. We have also computed the rotational and ro-vibrational emissions expected from H2, CO, and OH, and we discuss how complementary observations of such emissions may be used to further constrain the shock conditions. In common with previous studies, we come close to matching the observed H2, and high-J CO emissions from the Orion-KL star-forming region on the basis of a single shock model. We present our predictions for the strengths of H2O line emission from the Orion shock, and we show how our results may be scaled to other regions where molecular shocks are likely to be present.

  19. 1993 Northern goshawk inventory on portions of Los Alamos National Laboratory, Los Alamos, NM. Final report

    SciTech Connect

    Sinton, D.T.; Kennedy, P.L.

    1994-06-01

    Northern goshawks (Accipiter gentilis) (hereafter referred to as goshawk) is a large forest dwelling hawk. Goshawks may be declining in population and reproduction in the southwestern United States. Reasons for the possible decline in goshawk populations include timber harvesting resulting in the loss of nesting habitat, toxic chemicals, and the effects of drought, fire, and disease. Thus, there is a need to determine their population status and assess impacts of management activities in potential goshawk habitat. Inventory for the goshawk was conducted on 2,254 ha of Los Alamos National Laboratory (LANL) to determine the presence of nesting goshawks on LANL lands. This information can be incorporated into LANL`s environmental management program. The inventory was conducted by Colorado State University personnel from May 12 to July 30, 1993. This report summarizes the results of this inventory.

  20. Integrated review software advances at Los Alamos

    SciTech Connect

    Klosterbuer, S. F.; Michel, K. D.; Betts, S. E.; Determan, J. C.; Longo, J. F.; Parker, R. F.; Pelowitz, D. G.; Rothrock, R. B.; Schneider, C. M.; Nordquist, H. M.

    2004-01-01

    Since 1988, Los Alamos National Laboratory (LANL) has been developing software for unattended monitoring systems. These systems are composed of three categories of software: acquisition, collection and review. The data acquisition software is contained in modular instrumentation distributed throughout facilities to continuously acquire data from devices ranging from radiation detectors to cameras to binary switches. The data collection software runs on computers connected to the instruments and offloads and stores the acquired data. The review software enables the end user to quickly and easily examine the data collected from these different systems and compare the results to declared operator activities. This paper addresses the review software. The original standalone review software processed only radiation data. This software was expanded to include new programs (tools) to display and correlate video and operator declarations and added an interface to the standard neutron coincidence counter analysis program. This expanded review software containing multiple review tools is referred to collectively as the Integrated Review Software (IRS). The IRS continues to expand and evolve. Two primary IRS developments will be described in this paper. First, the IRS was expanded to include review tools to display and analyze new data types. Position Review was developed to display Global Positioning System (GPS) location data to aid in tracking radiation movements. Isotopic Review is being developed to provide a link to the standard gamma isotopic analysis software. In addition significant enhancements are being added to the existing review tools such as Operator Review, Radiation Review and Digital Video Review. A second IRS development is to produce standardized components with published interfaces enabling other parties to produce custom components that plug into review software. It is anticipated that there will be four primary types of components that could be

  1. Evidence for a thermally unstable shock wave in the Vela supernova remnant

    NASA Technical Reports Server (NTRS)

    Raymond, John C.; Wallerstein, George; Balick, Bruce

    1991-01-01

    The emission and absorption line signatures of supernova remnant shock waves provide complementary diagnostic capabilities. This paper presents IUE spectra of the nebulosity and new spectra of HD 72088. Models of the emission and absorption lines from shocked gas are used to derive a shock velocity and elemental depletions. There is evidence from the absorption-line strengths and widths for thermally unstable cooling behind a 150 km/s shock. The shock velocity and swept-up column density estimates of Wallerstein and Balick (1990) are confirmed, and evidence is found for a nonthermal contribution to the pressure.

  2. Shock/shock interference on a transpiration cooled hemispherical model

    NASA Technical Reports Server (NTRS)

    Nowak, Robert J.; Wieting, Allan R.; Holden, Michael S.

    1990-01-01

    Experimental results are presented which show the effectiveness of transpiration cooling in reducing the peak heat flux caused by an impinging shock on a bow shock of a hemispherical model. The 12-inch diameter hemispherical transpiration model with helium coolant was tested in the Calspan 48-inch Hypersonic Shock Tunnel at nominal Mach 12.1 and freestream unit Reynolds number of 0.33 x 10 to the 6th/ft. An incident shock wave, generated by a blunt flat-plate shock generator inclined at 10 deg to the freestream, intersected the bow shock of the model to produce shock/shock interference. The stagnation heat flux without coolant or shock/shock interference was about 1.6 times a smooth surface laminar prediction due to effective roughness of the coolant ejection slots. A coolant mass flux 31 percent of the freestream mass flux reduced the stagnation heat flux to zero without shock/shock interference. However, for the same coolant mass flux and with shock/shock interference the peak heat flux was only reduced 8.3 percent, even though the total integrated heat load was reduced.

  3. High Energy Concentration by Spherical Converging Shocks in a Shock Tube with Conically Shaped Test Section

    NASA Astrophysics Data System (ADS)

    Apazidis, N.; Kjellander, M.; Tillmark, N.

    Converging shock waves have been extensively investigated during the past several decades. Continuing interest in this research is motivated by the ability to obtain extreme conditions in gas in the focal region. In a pioneering work, Guderley [1], (1942) published a self-similar solution of the amplification of strong converging spherical and cylindrical shock waves close to the center of convergence. Another solution to the problem was presented by Stanyukovich [2], and since then a large number of analytical and numerical studies have been conducted, see e.g. Refs. [3, 4, 5, 6, 7, 8].

  4. Nonequilibrium molecular motion in a hypersonic shock wave.

    PubMed

    Pham-Van-Diep, G; Erwin, D; Muntz, E P

    1989-08-11

    Molecular velocities have been measured inside a hypersonic, normal shock wave, where the gas experiences rapid changes in its macroscopic properties. As first hypothesized by Mott-Smith, but never directly observed, the molecular velocity distribution exhibits a qualitatively bimodal character that is derived from the distribution functions on either side of the shock. Quantitatively correct forms of the molecular velocity distribution function in highly nonequilibrium flows can be calculated, by means of the Direct Simulation Monte Carlo technique.

  5. Radiative Shocks And Plasma Jets As Laboratory Astrophysics Experiments

    SciTech Connect

    Koenig, M.; Loupias, B.; Vinci, T.; Ozaki, N.; Benuzzi-Mounaix, A.; Rabec le Goahec, M.; Falize, E.; Bouquet, S.; Courtois, C.; Nazarov, W.; Aglitskiy, Y.; Faenov, A. Ya.; Pikuz, T.; Schiavi, A.

    2007-08-02

    Dedicated laboratory astrophysics experiments have been developed at LULI in the last few years. First, a high velocity (70 km/s) radiative shock has been generated in a xenon filled gas cell. We observed a clear radiative precursor, measure the shock temperature time evolution in the xenon. Results show the importance of 2D radiative losses. Second, we developed specific targets designs in order to generate high Mach number plasma jets. The two schemes tested are presented and discussed.

  6. Radiative Shocks And Plasma Jets As Laboratory Astrophysics Experiments

    NASA Astrophysics Data System (ADS)

    Koenig, M.; Loupias, B.; Vinci, T.; Ozaki, N.; Benuzzi-Mounaix, A.; Rabec Le Goahec, M.; Falize, E.; Bouquet, S.; Michaut, C.; Herpe, G.; Baroso, P.; Nazarov, W.; Aglitskiy, Y.; Faenov, A. Ya.; Pikuz, T.; Courtois, C.; Woolsey, N. C.; Gregory, C. D.; Howe, J.; Schiavi, A.; Atzeni, S.

    2007-08-01

    Dedicated laboratory astrophysics experiments have been developed at LULI in the last few years. First, a high velocity (70 km/s) radiative shock has been generated in a xenon filled gas cell. We observed a clear radiative precursor, measure the shock temperature time evolution in the xenon. Results show the importance of 2D radiative losses. Second, we developed specific targets designs in order to generate high Mach number plasma jets. The two schemes tested are presented and discussed.

  7. Water Supply at Los Alamos 1998-2001

    SciTech Connect

    Richard J. Koch; David B. Rogers

    2003-03-01

    For the period 1998 through 2001, the total water used at Los Alamos from all sources ranged from 1325 million gallons (Mg) in 1999 to 1515 Mg in 2000. Groundwater production ranged from 1323 Mg in 1999 to 1506 Mg in 2000 from the Guaje, Pajarito, and Otowi fields. Nonpotable surface water used from Los Alamos reservoir ranged from zero gallons in 2001 to 9.3 Mg in 2000. For years 1998 through 2001, over 99% of all water used at Los Alamos was groundwater. Water use by Los Alamos National Laboratory (LANL) between 1998 and 2001 ranged from 379 Mg in 2000 to 461 Mg in 1998. The LANL water use in 2001 was 393 Mg or 27% of the total water use at Los Alamos. Water use by Los Alamos County ranged from 872 Mg in 1999 to 1137 Mg in 2000, and averaged 1006 Mg/yr. Four new replacement wells in the Guaje field (G-2A, G-3A, G-4A, and G-5A) were drilled in 1998 and began production in 1999; with existing well G-1A, the Guaje field currently has five producing wells. Five of the old Guaje wells (G-1, G-2, G-4, G-5, and G-6) were plugged and abandoned in 1999, and one well (G-3) was abandoned but remains as an observation well for the Guaje field. The long-term water level observations in production and observation (test) wells at Los Alamos are consistent with the formation of a cone of depression in response to water production. The water level decline is gradual and at most has been about 0.7 to 2 ft per year for production wells and from 0.4 to 0.9 ft/yr for observation (test) wells. The largest water level declines have been in the Guaje field where nonpumping water levels were about 91 ft lower in 2001 than in 1951. The initial water levels of the Guaje replacement wells were 32 to 57 ft lower than the initial water levels of adjacent original Guaje wells. When production wells are taken off-line for pump replacement or repair, water levels have returned to within about 25 ft of initial static levels within 6 to 12 months. Thus, the water-level trends suggest no adverse

  8. A progress report on UNICOS misuse detection at Los Alamos

    SciTech Connect

    Thompson, J.L.; Jackson, K.A.; Stallings, C.A.; Simmonds, D.D.; Siciliano, C.L.B.; Pedicini, G.A.

    1995-10-01

    An effective method for detecting computer misuse is the automatic monitoring and analysis of on-line user activity. During the past year, Los Alamos enhanced its Network Anomaly Detection and Intrusion Reporter (NADIR) to include analysis of user activity on Los Alamos` UNICOS Crays. In near real-time, NADIR compares user activity to historical profiles and tests activity against expert rules. The expert rules express Los Alamos` security policy and define improper or suspicious behavior. NADIR reports suspicious behavior to security auditors and provides tools to aid in follow-up investigations. This paper describes the implementation to date of the UNICOS component of NADIR, along with the operational experiences and future plans for the system.

  9. Publications of Los Alamos research, 1977-1981

    SciTech Connect

    Sheridan, C.J.; Garcia, C.A.

    1983-03-01

    This bibliography is a compilation of unclassified publications of work done at the Los Alamos National Laboratory for 1977-1981. Papers published in those years are included regardless of when they were actually written. Publications received too late for inclusion in earlier compilations have also been listed. Declassification of previously classified reports is considered to constitute publication. All classified issuances are omitted - even those papers, themselves unclassified, which were published only as part of a classified document. If a paper was published more than once, all places of publication are included. The bibliography includes Los Alamos National Laboratory reports, papers released as non-Laboratory reports, journal articles, books, chapters of books, conference papers either published separately or as part of conference proceedings issued as books or reports, papers published in congressional hearings, theses, and US patents. Publications by Los Alamos authors that are not records of Laboratory-sponsored work are included when the Library becomes aware of them.

  10. Shock dynamics of phase diagrams

    NASA Astrophysics Data System (ADS)

    Moro, Antonio

    2014-04-01

    A thermodynamic phase transition denotes a drastic change of state of a physical system due to a continuous change of thermodynamic variables, as for instance pressure and temperature. The classical van der Waals equation of state is the simplest model that predicts the occurrence of a critical point associated with the gas-liquid phase transition. Nevertheless, below the critical temperature theoretical predictions of the van der Waals theory significantly depart from the observed physical behaviour. We develop a novel approach to classical thermodynamics based on the solution of Maxwell relations for a generalised family of nonlocal entropy functions. This theory provides an exact mathematical description of discontinuities of the order parameter within the phase transition region, it explains the universal form of the equations of state and the occurrence of triple points in terms of the dynamics of nonlinear shock wave fronts.

  11. Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves

    NASA Technical Reports Server (NTRS)

    Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.

    2015-01-01

    Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities 200 km s(exp -1) for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of approximately 2 compared to those of Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of approximately 3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of approximately 2-3 Gyr. These increases, while not able resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step towards understanding the origin, and evolution of dust in the ISM.

  12. Nature of the wiggle instability of galactic spiral shocks

    SciTech Connect

    Kim, Woong-Tae; Kim, Yonghwi; Kim, Jeong-Gyu E-mail: kimyh@astro.snu.ac.kr

    2014-07-01

    Gas in disk galaxies interacts nonlinearly with an underlying stellar spiral potential to form galactic spiral shocks. While numerical simulations typically show that spiral shocks are unstable to wiggle instability (WI) even in the absence of magnetic fields and self-gravity, its physical nature has remained uncertain. To clarify the mechanism behind the WI, we conduct a normal-mode linear stability analysis and nonlinear simulations assuming that the disk is isothermal and infinitesimally thin. We find that the WI is physical, originating from the generation of potential vorticity at a deformed shock front, rather than Kelvin-Helmholtz instabilities as previously thought. Since gas in galaxy rotation periodically passes through the shocks multiple times, the potential vorticity can accumulate successively, setting up a normal mode that grows exponentially with time. Eigenfunctions of the WI decay exponentially downstream from the shock front. Both shock compression of acoustic waves and a discontinuity of shear across the shock stabilize the WI. The wavelength and growth time of the WI depend on the arm strength quite sensitively. When the stellar-arm forcing is moderate at 5%, the wavelength of the most unstable mode is about 0.07 times the arm-to-arm spacing, with the growth rate comparable to the orbital angular frequency, which is found to be in good agreement with the results of numerical simulations.

  13. Nonequilibrium chemistry in shocked molecular clouds. [interstellar gases

    NASA Technical Reports Server (NTRS)

    Iglesias, E. R.; Silk, J.

    1978-01-01

    The gas-phase chemistry is studied behind a 10-km/s shock propagating into a dense molecular cloud. The principal conclusions are that: the concentrations of certain molecules (CO, NH3, HCN, N2) are unperturbed by the shock; other molecules (H2CO, CN, HCO(+)) are greatly decreased in abundance; and substantial amounts of H2O, HCO, and CH4 are produced. Approximately 1 million yr (independent of the density) must elapse after shock passage before chemical equilibrium is attained.

  14. MAGNETIC METHOD FOR PRODUCING HIGH VELOCITY SHOCK WAVES IN GASES

    DOEpatents

    Josephson, V.

    1960-01-26

    A device is described for producing high-energy plasmas comprising a tapered shock tube of dielectric material and having a closed small end, an exceedingly low-inductance coll supported about and axially aligned with the small end of the tapered tube. an elongated multiturn coil supported upon the remninder of the exterior wall of the shock tube. a potential source and switch connected in series with the low-inductance coil, a potential source and switch connected in series with the elongated coil, means for hermetically sealing the large end of the tube, means for purging the tube of gases, and means for admitting a selected gas into the shock tube.

  15. Nonstandard Analysis and Jump Conditions for Converging Shock Waves

    NASA Technical Reports Server (NTRS)

    Baty, Roy S.; Farassat, Fereidoun; Tucker, Don H.

    2008-01-01

    Nonstandard analysis is an area of modern mathematics which studies abstract number systems containing both infinitesimal and infinite numbers. This article applies nonstandard analysis to derive jump conditions for one-dimensional, converging shock waves in a compressible, inviscid, perfect gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are introduced to model the flow parameters across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters.

  16. Water supply at Los Alamos during 1993. Progress report

    SciTech Connect

    Purtymun, W.D.; Stoker, A.K.; McLin, S.G.; Maes, M.N.; Glasco, T.A.

    1995-10-01

    This report summarizes production and aquifer conditions for water wells in the Guaje, Pajarito, and Otowi Well Fields. These wells supplied all of the potable water used for municipal and some industrial purposes in Los Alamos County and the Los Alamos National Laboratory during 1993. The wells in the Los Alamos Well Field were transferred to San Ildefonso Pueblo in 1992. Four of the wells in the Los Alamos Well Field were plugged in 1993. One of the two new wells in the Otowi Well Field became operational in 1993. The spring gallery in Water Canyon supplied nonpotable water for industrial use, while surface water from the Los Alamos Reservoir was diverted for irrigation. In 1993 no water was used from the Guaje Reservoir. Due to the maintenance and operating cost of diverting water from the reservoirs, it is not economically feasible to continue their use for irrigation. This report fulfills some of the requirements of the Los Alamos Groundwater Protection Management Program by documenting use of the groundwater for water supply and providing information hydrologic characteristics of the main aquifer. This report is a joint effort between the Laboratory Water Quality and Hydrology Group and the Utilities Department of Johnson Controls World Services Inc. (JCI). The purpose of this report is to ensure a continuing historical record and to provide guidance for management of water resources in long-range planning for the water supply system. We have issued one summary report for the period of 1947 to 1971 and 22 annual reports that contain the results of our studies of these water supplies. An additional report summarized the hydrology of the main aquifer with reference to future development of groundwater supplies. A report was issued in 1988 that examined the status of wells and future water supply.

  17. The development of the atomic bomb, Los Alamos

    SciTech Connect

    Seidel, R.W.

    1993-11-01

    The historical presentation begins with details of the selection of Los Alamos as the site of the Army installation. Wartime efforts of the Army Corps of Engineers, and scientists to include the leader of Los Alamos, Robert Oppenheimer are presented. The layout and construction of the facilities are discussed. The monumental design requirements of the bombs are discussed, including but not limited to the utilization of the second choice implosion method of detonation, and the production of bomb-grade nuclear explosives. The paper ends with a philosophical discussion on the use of nuclear weapons.

  18. Los Alamos Using Neutrons to Stop Nuclear Smugglers

    ScienceCinema

    Favalli, Andrea; Swinhoe, Martyn

    2016-07-12

    Los Alamos National Laboratory researchers have successfully demonstrated for the first time that laser-generated neutrons can be enlisted as a useful tool in the War on Terror. The international research team used the short-pulse laser at Los Alamos's TRIDENT facility to generate a neutron beam with novel characteristics that interrogated a closed container to confirm the presence and quantity of nuclear material inside. The successful experiment paves the way for creation of a table-top-sized or truck-mounted neutron generator that could be installed at strategic locations worldwide to thwart smugglers trafficking in nuclear materials.

  19. Fifty-one years of Los Alamos Spacecraft

    SciTech Connect

    Fenimore, Edward E.

    2014-09-04

    From 1963 to 2014, the Los Alamos National Laboratory was involved in at least 233 spacecraft. There are probably only one or two institutions in the world that have been involved in so many spacecraft. Los Alamos space exploration started with the Vela satellites for nuclear test detection, but soon expanded to ionospheric research (mostly barium releases), radioisotope thermoelectric generators, solar physics, solar wind, magnetospheres, astrophysics, national security, planetary physics, earth resources, radio propagation in the ionosphere, and cubesats. Here, we present a list of the spacecraft, their purpose, and their launch dates for use during RocketFest

  20. A physicists guide to The Los Alamos Primer

    NASA Astrophysics Data System (ADS)

    Reed, B. Cameron

    2016-11-01

    In April 1943, a group of scientists at the newly established Los Alamos Laboratory were given a series of lectures by Robert Serber on what was then known of the physics and engineering issues involved in developing fission bombs. Serber’s lectures were recorded in a 24 page report titled The Los Alamos Primer, which was subsequently declassified and published in book form. This paper describes the background to the Primer and analyzes the physics contained in its 22 sections. The motivation for this paper is to provide a firm foundation of the background and contents of the Primer for physicists interested in the Manhattan Project and nuclear weapons.

  1. Contributions of chemistry in early day Los Alamos

    SciTech Connect

    Penneman, R.A.; Meade, R.A.

    1990-01-01

    During 1943--1945, the premier physics laboratory in the world was at Los Alamos, but chemistry contributions were vital. Major chemical impacts on the success of the Los Alamos wartime mission included electrochemistry, which found the true melting point of plutonium metal to be hundreds of degrees lower than anticipated. This discovery had profound simplifying effects regarding crucibles to contain molten plutonium and on its production. Other significant chemical contributions involved constant purification of plutonium for reuse, producing carrier-free gamma sources at unprecedented kilo-curie levels, and high polonium work. 8 refs.

  2. Los Alamos Using Neutrons to Stop Nuclear Smugglers

    SciTech Connect

    Favalli, Andrea; Swinhoe, Martyn

    2013-06-03

    Los Alamos National Laboratory researchers have successfully demonstrated for the first time that laser-generated neutrons can be enlisted as a useful tool in the War on Terror. The international research team used the short-pulse laser at Los Alamos's TRIDENT facility to generate a neutron beam with novel characteristics that interrogated a closed container to confirm the presence and quantity of nuclear material inside. The successful experiment paves the way for creation of a table-top-sized or truck-mounted neutron generator that could be installed at strategic locations worldwide to thwart smugglers trafficking in nuclear materials.

  3. MOLECULAR TRACERS OF TURBULENT SHOCKS IN GIANT MOLECULAR CLOUDS

    SciTech Connect

    Pon, A.; Johnstone, D.; Kaufman, M. J. E-mail: Douglas.Johnstone@nrc-cnrc.gc.ca

    2012-03-20

    Giant molecular clouds contain supersonic turbulence and simulations of magnetohydrodynamic turbulence show that these supersonic motions decay in roughly a crossing time, which is less than the estimated lifetimes of molecular clouds. Such a situation requires a significant release of energy. We run models of C-type shocks propagating into gas with densities around 10{sup 3} cm{sup -3} at velocities of a few km s{sup -1}, appropriate for the ambient conditions inside of a molecular cloud, to determine which species and transitions dominate the cooling and radiative energy release associated with shock cooling of turbulent molecular clouds. We find that these shocks dissipate their energy primarily through CO rotational transitions and by compressing pre-existing magnetic fields. We present model spectra for these shocks, and by combining these models with estimates for the rate of turbulent energy dissipation, we show that shock emission should dominate over emission from unshocked gas for mid to high rotational transitions (J > 5) of CO. We also find that the turbulent energy dissipation rate is roughly equivalent to the cosmic-ray heating rate and that the ambipolar diffusion heating rate may be significant, especially in shocked gas.

  4. Computation of Thermally Perfect Properties of Oblique Shock Waves

    NASA Technical Reports Server (NTRS)

    Tatum, Kenneth E.

    1996-01-01

    A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon a value of cp expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135, and with a state-of-the-art computational fluid dynamics code. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use, and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).

  5. Computation of Thermally Perfect Oblique Shock Wave Properties

    NASA Technical Reports Server (NTRS)

    Tatum, Kenneth E.

    1997-01-01

    A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon the specific heat expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).

  6. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    PubMed

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

  7. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen

    PubMed Central

    Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent. PMID:27603017

  8. Tailoring the Blast Exposure Conditions in the Shock Tube for Generating Pure, Primary Shock Waves: The End Plate Facilitates Elimination of Secondary Loading of the Specimen.

    PubMed

    Kuriakose, Matthew; Skotak, Maciej; Misistia, Anthony; Kahali, Sudeepto; Sundaramurthy, Aravind; Chandra, Namas

    2016-01-01

    The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Shock wave characteristics were monitored by high response rate pressure sensors allocated in six positions along the length of 6 meters long 229 mm square cross section shock tube. Tests were performed at three shock wave intensities, which was controlled by varying the Mylar membrane thickness (0.02, 0.04 and 0.06 inch). The end reflector plate installed at the exit of the shock tube allows precise control over the intensity of reflected waves penetrating into the shock tube. At the optimized distance of the tube to end plate gap the secondary waves were entirely eliminated from the test section, which was confirmed by pressure sensor at T4 location. This is pronounced finding for implementation of pure primary blast wave animal model. These data also suggest only deep in the shock tube experimental conditions allow exposure to a single shock wave free of artifacts. Our results provide detailed insight into spatiotemporal dynamics of shock waves with Friedlander waveform generated using helium as a driver gas and propagating in the air inside medium sized tube. Diffusion of driver gas (helium) inside the shock tube was responsible for velocity increase of reflected shock waves. Numerical simulations combined with experimental data suggest the shock wave attenuation mechanism is simply the expansion of the internal pressure. In the absence of any other postulated shock wave decay mechanisms, which were not implemented in the model the agreement between theory and experimental data is excellent.

  9. A method for predicting shock shapes and pressure distributions on two dimensional airfoils at large angles of attack

    NASA Technical Reports Server (NTRS)

    Kaattari, G. E.

    1973-01-01

    A method is presented for determining shock envelopes and pressure distributions for two-dimensional airfoils at angles of attack sufficiently large to cause shock detachment and subsonic flow over the windward surface of the airfoil. Correlation functions obtained from exact solutions are used to relate the shock standoff distance at the stagnation and sonic points of the body through a suitable choice for the shock shape. The necessary correlation functions were obtained from perfect gas solutions but may be extended to any gas flow for which the normal shock-density ratio can be specified.

  10. Modeling of shocks in young and old supernova remnants

    NASA Astrophysics Data System (ADS)

    Patnaude, Daniel James

    We present results from a modeling effort of simple shock phenomena in the Cygnus Loop and Cassiopeia A. Using multi-epoch MDM observations of a small, isolated cloud in the southwest region of the Cygnus Loop, we measure the velocity of the Balmer-dominated shock filaments as well as the velocity of the internal cloud shock. These results are used to constrain the primary parameter for interstellar clouds: the density contrast between the cloud and the interstellar medium. These results are used to present models for a strong shock interacting with a lumpy, but diffuse cloud. This model represents a refinement over previous shock-cloud models. Using multi-epoch X-ray observations of the Cassiopeia A supernova remnant, we investigate a small bow shock which protrudes north of the identified forward shock front. Proper motion estimates for this object, combined with a spectral analysis suggest that the object is a bullet of ejecta, similar to those found in Vela. Model results are presented which show the evolution of an ejecta bullet across the SNR. These simulations suggest that bullet ejecta could arise in Cas A, and that the bullet material could survive the turbulent journey through shocked ejecta. Finally, preliminary results from a study of the reverse shock structure in Cas A are presented. We present regions which show decaying fluxes over a four year period, but also show an increase in X-ray line emission, suggesting that the gas in these regions is approaching ionization equilibrium. Models for reverse shock formation and the reverse shock-ejecta interaction are discussed.

  11. A new shock wave assisted sandalwood oil extraction technique

    NASA Astrophysics Data System (ADS)

    Arunkumar, A. N.; Srinivasa, Y. B.; Ravikumar, G.; Shankaranarayana, K. H.; Rao, K. S.; Jagadeesh, G.

    A new shock wave assisted oil extraction technique from sandalwood has been developed in the Shock Waves Lab, IISc, Bangalore. The fragrant oil extracted from sandalwood finds variety of applications in medicine and perfumery industries. In the present method sandal wood specimens (2.5mm diameter and 25mm in length)are subjected to shock wave loading (over pressure 15 bar)in a constant area shock tube, before extracting the sandal oil using non-destructive oil extraction technique. The results from the study indicates that both the rate of extraction as well as the quantity of oil obtained from sandal wood samples exposed to shock waves are higher (15-40 percent) compared to non-destructive oil extraction technique. The compressive squeezing of the interior oil pockets in the sandalwood specimen due to shock wave loading appears to be the main reason for enhancement in the oil extraction rate. This is confirmed by the presence of warty structures in the cross-section and micro-fissures in the radial direction of the wood samples exposed to shock waves in the scanning electron microscopic investigation. In addition the gas chromatographic studies do not show any change in the q uality of sandal oil extracted from samples exposed to shock waves.

  12. Shock wave treatment in medicine.

    PubMed

    Shrivastava, S K; Kailash

    2005-03-01

    Extracorporeal shock wave therapy in orthopedics and traumatology is still a young therapy method. Since the last few years the development of shock wave therapy has progressed rapidly. Shock waves have changed the treatment of urolithiasis substantially. Today shock waves are the first choice to treat kidney and urethral stones. Urology has long been the only medical field for shock waves in medicine. Meanwhile shock waves have been used in orthopedics and traumatology to treat insertion tendinitis, avascular necrosis of the head of femur and other necrotic bone alterations. Another field of shock wave application is the treatment of tendons, ligaments and bones on horses in veterinary medicine. In the present paper we discuss the basic theory and application of shock waves and its history in medicine. The idea behind using shock wave therapy for orthopedic diseases is the stimulation of healing in tendons, surrounding tissue and bones. PMID:15933416

  13. Needs assessment for fire department services and resources for the Los Alamos National Laboratory, Los Alamos, New Mexico. Final report

    SciTech Connect

    1995-11-15

    This report has been developed in response to a request from the Los Alamos National Laboratory (LANL) to evaluate the need for fire department services so as to enable the Laboratory to plan effective fire protection and thereby: meet LANL`s regulatory and contractual obligations; interface with the Department of Energy (DOE) and other agencies on matters relating to fire and emergency services; and ensure appropriate protection of the community and environment. This study is an outgrowth of the 1993 Fire Department Needs Assessment (prepared for DOE) but is developed from the LANL perspective. Input has been received from cognizant and responsible representatives at LANL, DOE, Los Alamos County (LAC) and the Los Alamos Fire Department (LAFD).

  14. Shocks in fragile matter

    NASA Astrophysics Data System (ADS)

    Vitelli, Vincenzo

    2012-02-01

    Non-linear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they unjam, these fragile and disordered solids exhibit vanishing elastic moduli and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are continuously compressed, and demonstrate that the resulting excitations are strongly nonlinear shocks, rather than linear waves. We capture the full dependence of the shock speed on pressure and compression speed by a surprisingly simple analytical model. We also treat shear shocks within a simplified viscoelastic model of nearly-isostatic random networks comprised of harmonic springs. In this case, anharmonicity does not originate locally from nonlinear interactions between particles, as in granular media; instead, it emerges from the global architecture of the network. As a result, the diverging width of the shear shocks bears a nonlinear signature of the diverging isostatic length associated with the loss of rigidity in these floppy networks.

  15. Hot spot initiation and chemical reaction in shocked polymeric bonded explosives

    NASA Astrophysics Data System (ADS)

    An, Qi; Zybin, Sergey; Jaramillo-Botero, Andres; Goddard, William; Materials; Process Simulation Center, Caltech Team

    2011-06-01

    A polymer bonded explosive (PBX) model based on PBXN-106 is studied via molecular dynamics (MD) simulations using reactive force field (ReaxFF) under shock loading conditions. Hotspot is observed when shock waves pass through the non-planar interface of explosives and elastomers. Adiabatic shear localization is proposed as the main mechanism of hotspot ignition in PBX for high velocity impact. Our simulation also shows that the coupling of shear localization and chemical reactions at hotspot region play important rules at stress relaxtion for explosives. The phenomenon that shock waves are obsorbed by elastomers is also observed in the MD simulations. This research received supports from ARO (W911NF-05-1-0345; W911NF-08-1-0124), ONR (N00014-05-1-0778), and Los Alamos National Laboratory (LANL).

  16. Shocked Molecular Hydrogen in the Orion ``Bullets''

    NASA Astrophysics Data System (ADS)

    Tedds, Jonathan A.

    1997-03-01

    The physics of shocked outflows in molecular clouds is one of the fundamental astrophysical processes by which the cycle of star formation in our Galaxy is regulated. I outline the basis of our understanding of the star formation process and the viol ent outflow always associated with it, the physics of shocks in molecular gas, and the consequent excitation of molecular hydrogen (H2). It is demonstrated that molecular hydrogen is the best observational diagnostic of this hot, shocked molecular gas and an introduction is given to the observational techniques of near-infrared spectroscopy required in its measurement. I describe a detailed observational study of the physics of shocked H2 excitation and dynamics in the nearby massive star forming re gion of the Orion giant molecular cloud, the brightest source of its type, using the recently upgraded CGS4 near-IR spectrometer at UKIRT. We have demonstrated that integrated [FeII] 1.644micron line profiles in the Orion ``bullets'' are consistent with theoretical bow-shock predictions for two different ``bullets''. We have identified a uniform, broad background component pervading the region in both Fe+ and H2 which is inconsistent with a fluorescent component due to the ionizing radiation of the Trapezium stars alone. A collisionally broadened background component of unidentified origin is measured to be Gaussian in profile with an average FWHM of 26 +/- 2.5kms-1 in the H2 1-0 S(1) line after deconvolution of the instrumental profile and a peak velocity of 2.5 +/- 0.5kms-1, close to the local ambient rest velocity. Crucially, the extended H2 ``bullet'' wakes have allowed us to dissect individual molecular bow shock structures but the broad (intrinsic FWHM <= 27kms-1), singly-peaked H2 1-0 S(1) profiles observed in the two most clearly resolved, plane-of-sky oriented wakes challenge our present understanding. It is very difficult to reconcile any steady-state molecular bow shock model with these observations in Orion. To

  17. A survey of macromycete diversity at Los Alamos National Laboratory, Bandelier National Monument, and Los Alamos County; A preliminary report

    SciTech Connect

    Jarmie, N.; Rogers, F.J.

    1997-11-01

    The authors have completed a 5-year survey (1991--1995) of macromycetes found in Los Alamos County, Los Alamos National Laboratory, and Bandelier National Monument. The authors have compiled a database of 1,048 collections, their characteristics, and identifications. The database represents 123 (98%) genera and 175 (73%) species reliably identified. Issues of habitat loss, species extinction, and ecological relationships are addressed, and comparisons with other surveys are made. With this baseline information and modeling of this baseline data, one can begin to understand more about the fungal flora of the area.

  18. TIMING OF SHOCK WAVES

    DOEpatents

    Tuck, J.L.

    1955-03-01

    This patent relates to means for ascertaining the instant of arrival of a shock wave in an exploslve charge and apparatus utilizing this means to coordinate the timing of two operations involving a short lnterval of time. A pair of spaced electrodes are inserted along the line of an explosive train with a voltage applied there-across which is insufficient to cause discharge. When it is desired to initiate operation of a device at the time the explosive shock wave reaches a particular point on the explosive line, the device having an inherent time delay, the electrodes are located ahead of the point such that the ionization of the area between the electrodes caused by the traveling explosive shock wave sends a signal to initiate operation of the device to cause it to operate at the proper time. The operated device may be photographic equipment consisting of an x-ray illuminating tube.

  19. Life Shocks and Homelessness

    PubMed Central

    Corman, Hope; Noonan, Kelly; Reichman, Nancy E.

    2014-01-01

    We exploited an exogenous health shock—namely, the birth of a child with a severe health condition—to investigate the effect of a life shock on homelessness in large cities in the United States as well as the interactive effects of the shock with housing market characteristics. We considered a traditional measure of homelessness, two measures of housing instability thought to be precursors to homelessness, and a combined measure that approximates the broadened conceptualization of homelessness under the 2009 Homeless Emergency Assistance and Rapid Transition to Housing Act (2010). We found that the shock substantially increases the likelihood of family homelessness, particularly in cities with high housing costs. The findings are consistent with the economic theory of homelessness, which posits that homelessness results from a conjunction of adverse circumstances in which housing markets and individual characteristics collide. PMID:23868747

  20. A BOW SHOCK NEAR A YOUNG STAR

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA's Hubble Space Telescope continues to reveal various stunning and intricate treasures that reside within the nearby, intense star-forming region known as the Great Nebula in Orion. One such jewel is the bow shock around the very young star, LL Ori, featured in this Hubble Heritage image. Named for the crescent-shaped wave made by a ship as it moves through water, a bow shock can be created in space when two streams of gas collide. LL Ori emits a vigorous solar wind, a stream of charged particles moving rapidly outward from the star. Our own Sun has a less energetic version of this wind that is responsible for auroral displays on the Earth. The material in the fast wind from LL Ori collides with slow-moving gas evaporating away from the center of the Orion Nebula, which is located to the lower right in this Heritage image. The surface where the two winds collide is the crescent-shaped bow shock seen in the image. Unlike a water wave made by a ship, this interstellar bow shock is a three-dimensional structure. The filamentary emission has a very distinct boundary on the side facing away from LL Ori, but is diffuse on the side closest to the star, a characteristic common to many bow shocks. A second, fainter bow shock can be seen around a star near the upper right-hand corner of the Heritage image. Astronomers have identified numerous shock fronts in this complex star-forming region and are using this data to understand the many complex phenomena associated with the birth of stars. This image was taken in February 1995 as part of the Hubble Orion Nebula mosaic. A close visitor in our Milky Way galaxy, the nebula is only 1,500 light-years from Earth. The filters used in this color composite represent oxygen, nitrogen, and hydrogen emissions. Image Credit: NASA and the Hubble Heritage Team (STScI/AURA) Acknowledgment: C. R. O'Dell (Vanderbilt University)

  1. Culture shock and travelers.

    PubMed

    Stewart, L; Leggat, P A

    1998-06-01

    As travel has become easier and more affordable, the number of people traveling has risen sharply. People travel for many and varied reasons, from the business person on an overseas assignment to backpackers seeking new and exotic destinations. Others may take up residence in different regions, states or countries for family, business or political reasons. Other people are fleeing religious or political persecution. Wherever they go and for whatever reason they go, people take their culture with them. Culture, like language, is acquired innately in early childhood and is then reinforced through formal and complex informal social education into adulthood. Culture provides a framework for interpersonal and social interactions. Therefore, the contact with a new culture is often not the exciting or pleasurable experience anticipated. When immersed in a different culture, people no longer know how to act when faced with disparate value systems. Contact with the unfamiliar culture can lead to anxiety, stress, mental illness and, in extreme cases, physical illness and suicide. "Culture shock" is a term coined by the anthropologist Oberg. It is the shock of the new. It implies that the experience of the new culture is an unpleasant surprise or shock, partly because it is unexpected and partly because it can lead to a negative evaluation of one's own culture. It is also known as cross-cultural adjustment, being that period of anxiety and confusion experienced when entering a new culture. It affects people intellectually, emotionally, behaviorally and physically and is characterized by symptoms of psychological distress. Culture shock affects both adults and children. In travelers or workers who have prolonged sojourns in foreign countries, culture shock may occur not only as they enter the new culture, but also may occur on their return to their original culture. Children may also experience readjustment problems after returning from leading sheltered lives in expatriate

  2. Shock destruction armor system

    DOEpatents

    Froeschner, Kenneth E.

    1993-01-01

    A shock destruction armor system is constructed and arranged to destroy the force of impact of a projectile by shock hydrodynamics. The armor system is designed to comprise a plurality of superimposed armor plates each preferably having a thickness less than five times the projectile's diameter and are preferably separated one-from-another by a distance at least equal to one-half of the projectile's diameter. The armor plates are effective to hydrodynamically and sequentially destroy the projectile. The armor system is particularly adapted for use on various military vehicles, such as tanks, aircraft and ships.

  3. Shocks in nova outflows - II. Synchrotron radio emission

    NASA Astrophysics Data System (ADS)

    Vlasov, Andrey; Vurm, Indrek; Metzger, Brian D.

    2016-11-01

    The discovery of GeV gamma-rays from classical novae indicates that shocks and relativistic particle acceleration are energetically key in these events. Further evidence for shocks comes from thermal keV X-ray emission and an early peak in the radio light curve on a time-scale of months with a brightness temperature which is too high to result from freely expanding photoionized gas. Paper I developed a one-dimensional model for the thermal emission from nova shocks. This work concluded that the shock-powered radio peak cannot be thermal if line cooling operates in the post-shock gas at the rate determined by collisional ionization equilibrium. Here we extend this calculation to include non-thermal synchrotron emission. Applying our model to three classical novae, we constrain the amplification of the magnetic field ɛB and the efficiency ɛe of accelerating relativistic electrons of characteristic Lorentz factor γ ˜ 100. If the shocks are radiative (low velocity vsh ≲ 1000 km s-1) and cover a large solid angle of the nova outflow, as likely characterize those producing gamma-rays, then values of ɛe ˜ 0.01-0.1 are required to achieve the peak radio brightness for ɛB = 10-2. Such high efficiencies exclude secondary pairs from pion decay as the source of the radio-emitting particles, instead favouring the direct acceleration of electrons at the shock. If the radio-emitting shocks are instead adiabatic (high velocity), as likely characterize those responsible for the thermal X-rays, then much higher brightness temperatures are possible, allowing the radio-emitting shocks to cover a smaller outflow solid angle.

  4. Creating a Driven, Collapsed Radiative Shock in the Laboratory

    NASA Astrophysics Data System (ADS)

    Reighard, Amy

    2006-10-01

    We report details of the first experimental campaign to create a driven, planar, radiatively collapsed in laboratory experiment. Radiation hydrodynamics experiments are challenging to realize in a laboratory setting, requiring high temperatures in a system of sufficient extent. The Omega laser at ˜10^15 W/cm^2 drives a thin slab of low-Z material at >100 km/s gas via laser ablation pressure. This slab initially shocks, then continues driving a shock through a cylindrical volume of Xe gas at 6 mg/cc. Simulations predict a collapsed layer in which the density reaches ˜45 times initial density. Side-on x-ray backlighting was the principal diagnostic. We have successfully imaged shocks with average velocities between 95-205 km/sec, with measured thicknesses of 45-150 μm in experiments lasting up to 20 ns and spanning up 2.5 mm in extent. Comparison of the shock position as a function of time from these experiments to 1D radiation hydrodynamic simulation results show some discrepancy, which will be explored. Optical depth before and behind the shock is important for meaningful comparison to these astrophysical systems. This shock is optically thin to emitted radiation in the unshocked region and optically thick to radiation in the shocked, dense region. We compare this system to collapsed shocks in astrophysical systems with similar optical depth profiles. An experiment using a Thomson scattering diagnostic across the shock front is also discussed. This research was sponsored by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Research Grants DE-FG52-03NA00064, DE-FG53-2005-NA26014, and other grants and contracts.

  5. Shocks in nova outflows. II. Synchrotron radio emission

    NASA Astrophysics Data System (ADS)

    Vlasov, Andrey; Vurm, Indrek; Metzger, Brian D.

    2016-08-01

    The discovery of GeV gamma-rays from classical novae indicates that shocks and relativistic particle acceleration are energetically key in these events. Further evidence for shocks comes from thermal keV X-ray emission and an early peak in the radio light curve on a timescale of months with a brightness temperature which is too high to result from freely expanding photo-ionized gas. Paper I developed a one dimensional model for the thermal emission from nova shocks. This work concluded that the shock-powered radio peak cannot be thermal if line cooling operates in the post-shock gas at the rate determined by collisional ionization equilibrium. Here we extend this calculation to include non-thermal synchrotron emission. Applying our model to three classical novae, we constrain the amplification of the magnetic field ɛB and the efficiency ɛe of accelerating relativistic electrons of characteristic Lorentz factor γ ˜ 100. If the shocks are radiative (low velocity v_sh ≲ 1000 km s-1) and cover a large solid angle of the nova outflow, as likely characterize those producing gamma-rays, then values of ɛe ˜ 0.01 - 0.1 are required to achieve the peak radio brightness for ɛB = 10-2. Such high efficiencies exclude secondary pairs from pion decay as the source of the radio-emitting particles, instead favoring the direct acceleration of electrons at the shock. If the radio-emitting shocks are instead adiabatic (high velocity), as likely characterize those responsible for the thermal X-rays, then much higher brightness temperatures are possible, allowing the radio-emitting shocks to cover a smaller outflow solid angle.

  6. Technical manpower needs and resources at Los Alamos National Laboratory

    SciTech Connect

    Freese, K.B.

    1984-01-01

    The Los Alamos National Laboratory has begun a program to share its scientific and technological expertise with students and teachers in the surrounding area. The goal of the Laboratory's Educational Outreach Program is to stimulate an awareness of professional opportunities in the sciences and engineering.

  7. Summary of environmental surveillance at Los Alamos during 1995

    SciTech Connect

    1996-10-01

    Linking the Rio Grande Valley and the Jemez Mountains, New Mexico`s Pajarito Plateau is home to a world-class scientific institution. Los Alamos National Laboratory (or the Laboratory), managed by the Regents of the University of California, is a government-owned, Department of Energy-supervised complex investigating all areas of modern science for the purposes of national defense, health, conservation, and ecology. The Laboratory was founded in 1943 as part of the Manhattan Project, whose members assembled to create the first nuclear weapon. Occupying the campus of the Los Alamos Ranch School, American and British scientists gathered on the isolated mesa tops to harness recently discovered nuclear power with the hope of ending World War II. In July 1945, the initial objective of the Laboratory, a nuclear device, was achieved in Los Alamos and tested in White Sands, New Mexico. Today the Laboratory continues its role in defense, particularly in nuclear weapons, including developing methods for safely handling weapons and managing waste. For the past twenty years, the Laboratory has published an annual environmental report. This pamphlet offers a synopsis that briefly explains important concepts, such as radiation and provides a summary of the monitoring results and regulatory compliance status that are explained at length in the document entitled Environmental Surveillance at Los Alamos during 1995.

  8. Mercury: The Los Alamos ICF KrF laser system

    SciTech Connect

    Czuchlewski, S.J.; York, G.W.; Bigio, I.J.; Brucker, J.; Hanson, D.; Honig, E.M.; Kurnit, N.; Leland, W.; McCown, A.W.; McLeod, J.; Rose, E.; Thomas, S.; Thompson, D.

    1993-01-19

    The Mercury KrF laser facility at Los Alamos is being built with the benefit of lessons learned from the Aurora system. An increased understanding of KrF laser engineering, and the designed implementation of system flexibility, will permit Mercury to serve as a tested for a variety of advanced KrF technology concepts.

  9. The Controlled-Air Incinerator at Los Alamos

    SciTech Connect

    Newmyer, J.N.

    1994-04-01

    The Controlled-Air Incinerator (CAI) at Los Alamos is being modified and upgraded to begin routine operations treating low-level mixed waste (LLMW), radioactively contaminated polychlorinated biphenyl (PCB) wastes, low-level liquid wastes, and possibly transuranic (TRU) wastes. This paper describes those modifications. Routine waste operations should begin in late FY95.

  10. The Los Alamos Space Science Outreach (LASSO) Program

    NASA Astrophysics Data System (ADS)

    Barker, P. L.; Skoug, R. M.; Alexander, R. J.; Thomsen, M. F.; Gary, S. P.

    2002-12-01

    The Los Alamos Space Science Outreach (LASSO) program features summer workshops in which K-14 teachers spend several weeks at LANL learning space science from Los Alamos scientists and developing methods and materials for teaching this science to their students. The program is designed to provide hands-on space science training to teachers as well as assistance in developing lesson plans for use in their classrooms. The program supports an instructional model based on education research and cognitive theory. Students and teachers engage in activities that encourage critical thinking and a constructivist approach to learning. LASSO is run through the Los Alamos Science Education Team (SET). SET personnel have many years of experience in teaching, education research, and science education programs. Their involvement ensures that the teacher workshop program is grounded in sound pedagogical methods and meets current educational standards. Lesson plans focus on current LANL satellite projects to study the solar wind and the Earth's magnetosphere. LASSO is an umbrella program for space science education activities at Los Alamos National Laboratory (LANL) that was created to enhance the science and math interests and skills of students from New Mexico and the nation. The LASSO umbrella allows maximum leveraging of EPO funding from a number of projects (and thus maximum educational benefits to both students and teachers), while providing a format for the expression of the unique science perspective of each project.

  11. Optical velocimetry at the Los Alamos Proton Radiography Facility

    NASA Astrophysics Data System (ADS)

    Tupa, Dale; Tainter, Amy; Neukirch, Levi; Hollander, Brian; Buttler, William; Holtkamp, David; The Los Alamos Proton Radiography Team Team

    2016-05-01

    The Los Alamos Proton Radiography Facility (pRad) employs a high-energy proton beam to image the properties and behavior of materials driven by high explosives. We will discuss features of pRad and describe some recent experiments, highlighting optical diagnostics for surface velocity measurements.

  12. Working with Fermi at Chicago and Los Alamos

    NASA Astrophysics Data System (ADS)

    Garwin, Richard L.

    2010-02-01

    I discuss my experience with Enrico Fermi as student and fellow faculty member at Chicago and with him as consultants to the Los Alamos Scientific Laboratory in 1950-1952. The talk shares observations about this great physicist and exemplary human being. )

  13. Impact-shocked zircons: Discovery of shock-induced textures reflecting increasing degrees of shock metamorphism

    NASA Technical Reports Server (NTRS)

    Bohor, B. F.; Betterton, W. J.; Krogh, T. E.

    1993-01-01

    Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. However, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same environments. An etching technique was developed that allows scanning electron microscope (SEM) visualization of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of impact shock environments. These textural features in shocked zircons from K/T boundary distal ejecta form a series related to increasing degrees of shock that should correlate with proportionate resetting of the U-Pb isotopic system.

  14. Impact-shocked zircons: discovery of shock-induced textures reflecting increasing degrees of shock metamorphism

    USGS Publications Warehouse

    Bohor, B.F.; Betterton, W.J.; Krogh, T.E.

    1993-01-01

    Textural effects specifically characteristic of shock metamorphism in zircons from impact environments have not been reported previously. However, planar deformation features (PDF) due to shock metamorphism are well documented in quartz and other mineral grains from these same environments. An etching technique was developed that allows SEM visualization of PDF and other probable shock-induced textural features, such as granular (polycrystalline) texture, in zircons from a variety of impact shock environments. These textural features in shocked zircons from K/T boundary distal ejecta form a series related to increasing degrees of shock that should correlate with proportionate resetting of the UPb isotopic system. ?? 1993.

  15. Detonation shock dynamics calibration for non-ideal HE: ANFO

    SciTech Connect

    Short, Mark; Salyer, Terry R; Aslam, Tariq D; Kiyanda, Charles B; Morris, John S; Zimmerley, Tony

    2009-01-01

    Linear D{sub n}-{kappa} detonation shock dynamics (DSD) filling forms are obtained for four ammonium nitrate-fuel oil (ANFO) mixtures involving variations in the ammonium nitrate prill properties and ANFO stoichiometries. The detonation of ammonium nitrate-fuel oil (ANFO) mixtures is considered to be highly nonideal involving long reaction zones ({approx} several cms), low detonation energies and large failure diameters ({approx} 10s-100s cms). A number of experimental programs have been undertaken to understand ANFO detonation properties as a function of the AN properties [1]-[7]. Given the highly heterogeneous nature of ANFO mixtures (typical high explosive (HE) grade AN prills are porous with a range of diameters) a predictive reactive flow simulation of ANFO detonation will present significant challenges. At Los Alamos, a simulation capability has been developed for predicting the propagation of detonation in non-ideal HE and the work conducted on surrounding materials via a combination of a detonation shock dynamics (DSD) approach and a modified programmed burn method known as the pseudo-reaction-zone (or PRZ) method that accounts for the long detonation reaction zone. In the following, linear D{sub n}-{kappa} DSD fitting forms are obtained for four ammonium nitrate-fuel oil mixtures involving variation in the ammonium nitrate prill properties and ANFO stoichiometries. A detonation shock dynamics calibration for ANFO consisting of regular porous HE grade AN in a 94/6 wt.% AN to FO mix has been obtained in [7].

  16. Thermoacoustic natural gas liquefier

    SciTech Connect

    Swift, G.; Gardner, D.; Hayden, M.; Radebaugh, R.; Wollan, J.

    1996-07-01

    This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project sought to develop a natural-gas-powered natural-gas liquefier that has absolutely no moving parts and requires no electrical power. It should have high efficiency, remarkable reliability, and low cost. The thermoacoustic natural-gas liquefier (TANGL) is based on our recent invention of the first no-moving-parts cryogenic refrigerator. In short, our invention uses acoustic phenomena to produce refrigeration from heat, with no moving parts. The required apparatus comprises nothing more than heat exchangers and pipes, made of common materials, without exacting tolerances. Its initial experimental success in a small size lead us to propose a more ambitious application: large-energy liquefaction of natural gas, using combustion of natural gas as the energy source. TANGL was designed to be maintenance-free, inexpensive, portable, and environmentally benign.

  17. Shock waves data for minerals

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.; Johnson, Mary L.

    1994-01-01

    Shock compression of the materials of planetary interiors yields data which upon comparison with density-pressure and density-sound velocity profiles constrain internal composition and temperature. Other important applications of shock wave data and related properties are found in the impact mechanics of terrestrial planets and solid satellites. Shock wave equation of state, shock-induced dynamic yielding and phase transitions, and shock temperature are discussed. In regions where a substantial phase change in the material does not occur, the relationship between the particle velocity, U(sub p), and the shock velocity, U(sub s), is given by U(sub s) = C(sub 0) + S U(sub p), where C(sub 0) is the shock velocity at infinitesimally small particle velocity, or the ambient pressure bulk sound velocity. Numerical values for the shock wave equation of state for minerals and related materials of the solar system are provided.

  18. Study of a tissue protecting system for clinical applications of underwater shock wave

    NASA Astrophysics Data System (ADS)

    Hosseini, S. H. R.; Takayama, Kazuyoshi

    2005-04-01

    Applications of underwater shock waves have been extended to various clinical therapies during the past two decades. Besides the successful contribution of extracorporeal shock waves, tissue damage especially to the vasculature has been reported. These side effects are believed to be due to the shock wave-tissue interaction and cavitation. In the present research in order to minimize shock wave induced damage a shock wave attenuating system was designed and studied. The attenuating system consisted of thin gas packed layers immersed in water, which could attenuate more than 90% of shock waves overpressure. Silver azide micro-pellets (10 mg) were ignited by irradiation of a pulsed Nd:YAG laser to generate shock waves. Pressure histories were measured with fiber optic probe and PVDF needle hydrophones. The strength of incident shock waves was changed by adjusting the distance between the pellets and the layers. The whole sequences of the shock wave attenuation due to the interaction of shock waves with the dissipating layers were quantitatively visualized by double exposure holographic interferometry and time resolved high speed photography. The attenuated shock had overpressure less than threshold damage of brain tissue evaluated from histological examination of the rat brain treated by shock waves.

  19. The CHESS survey of the L1157-B1 shock: the dissociative jet shock as revealed by Herschel-PACS

    NASA Astrophysics Data System (ADS)

    Benedettini, M.; Busquet, G.; Lefloch, B.; Codella, C.; Cabrit, S.; Ceccarelli, C.; Giannini, T.; Nisini, B.; Vasta, M.; Cernicharo, J.; Lorenzani, A.; di Giorgio, A. M.

    2012-03-01

    Outflows generated by protostars heavily affect the kinematics and chemistry of the hosting molecular cloud through strong shocks that enhance the abundance of some molecules. L1157 is the prototype of chemically active outflows, and a strong shock, called B1, is taking place in its blue lobe between the precessing jet and the hosting cloud. We present the Herschel-PACS 55-210 μm spectra of the L1157-B1 shock, showing emission lines from CO, H2O, OH, and [O i]. The spatial resolution of the PACS spectrometer allows us to map the warm gas traced by far-infrared (FIR) lines with unprecedented detail. The rotational diagram of the high-Jup CO lines indicates high-excitation conditions (Tex ≃ 210 ± 10 K). We used a radiative transfer code to model the hot CO gas emission observed with PACS and in the CO (13-12) and (10-9) lines measured by Herschel-HIFI. We derive 200 < Tkin < 800 K and n ≥ 105 cm-3. The CO emission comes from a region of about 7'' located at the rear of the bow shock where the [O i] and OH emission also originate. Comparison with shock models shows that the bright [O i] and OH emissions trace a dissociative J-type shock, which is also supported by a previous detection of [FeII] at the same position. The inferred mass-flux is consistent with the "reverse" shock where the jet is impacting on the L1157-B1 bow shock. The same shock may contribute significantly to the high-Jup CO emission. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix A is available in electronic form at http://www.aanda.org

  20. Los Alamos Hot-Cell-Facility modifications for examining FFTF fuel pins

    SciTech Connect

    Campbell, B.M.; Ledbetter, J.M.

    1982-01-01

    Commissioned in 1960, the Wing 9 Hot Cell Facility at Los Alamos was recently modified to meet the needs of the 1980s. Because fuel pins from the Fast Flux Test Facility (FFTF) at the Hanford Engineering Development Laboratory (HEDL) are too long for examination in the original hot cells, we modified cells to accommodate longer fuel pins and to provide other capabilities as well. For instance, the T-3 shipping cask now can be opened in an inert atmosphere that can be maintained for all nondestructive and destructive examinations of the fuel pins. The full-length pins are visually examined and photographed, the wire wrap is removed, and fission gas is sampled. After the fuel pin is cropped, a cap is seal-welded on the section containing the fuel column. This section is then transferred to other cells for gamma-scanning, radiography, profilometry, sectioning for metallography, and chemical analysis.