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Sample records for high energy shock

  1. Shock wave generated by high-energy electric spark discharge

    NASA Astrophysics Data System (ADS)

    Liu, Qingming; Zhang, Yunming

    2014-10-01

    Shock wave generated by electric spark discharge was studied experimentally and the shock wave energy was evaluated in this paper. A pressure measurement system was established to study the pressure field of the electric spark discharge process. A series of electric spark discharge experiments were carried out and the energy of the electric spark used in present study was in the range of 10 J, 100 J, and 1000 J, respectively. The shock wave energy released from the electric spark discharge process was calculated by using the overpressure values at different measurement points near the electric spark discharge center. The good consistency of shock wave energies calculated by pressure histories at different measuring points in the same electric spark discharge experiment illustrates the applicability of the weak shock wave theory in calculating the energy of shock wave induced by electric spark discharge process. The result showed that shock wave formed at the initial stage of electric spark discharge process, and the shock wave energy is only a little part of electric spark energy. From the analysis of the shock wave energy and electric spark energy, a good linear relationship between shock wave energy and electric spark energy was established, which make it possible to calculate shock wave energy by measuring characteristic parameters of electric spark discharge process instead of shock wave. So, the initiation energy of direct initiation of detonation can be determined easily by measuring the parameters of electric spark discharge process.

  2. Scatttering of High-energy Particles at a Collisionless Shock Front: Dependence on the Shock Angle

    NASA Astrophysics Data System (ADS)

    Gedalin, M.; Dröge, W.; Kartavykh, Y. Y.

    2015-07-01

    Many shock acceleration theories deal with gyrophase-averaged particle distributions that depend only on the energy and pitch angle of the particles. Diffusive shock acceleration includes shock crossing as a necessary component. As long as the shock width is much smaller than the mean free path of a particle, the crossing is governed by the macroscopic fields inside the transition layer. The dynamics of high-energy particles in these fields is non-adiabatic and gyrophase dependent. The magnetic moment is not conserved in a wide range of shock angles, nor is the condition of reflection determined by the magnetic bottle relation. Instead, for a pitch angle and unknown gyrophase of an incident particle there is a finite probability of reflection. This probability varies between zero and unity in a wide range of pitch angles. In this work we investigate how the matching conditions at the shock front could be modified with the gyrophase dependence taken into account, e.g., in the form of the scattering probabilities.

  3. Laser Driven Radiative Shocks in High Energy Density

    NASA Astrophysics Data System (ADS)

    Manka, C.; Lunsford, R.; Nikitin, S.; Laming, M.; Zabatakis, D.; Grun, J.

    2008-03-01

    The long time over which oscillations associated with radiative shocks within the interstellar medium occur makes direct observation of these instabilities highly problematic. A velocity dependant cooling instability is thought to cause fluctuations in the propagation velocity of such shocks. An experiment at NRL investigates and perhaps validates the applicability of present analytic models to various multidimensional radiative shock instabilities. The PHAROS laser at NRL is used to create the relevant shock front by ablative acceleration of an aluminized Mylar foil that covers a small gas filled tunnel in a PMMA block. As this shock propagates along the tunnel, a secondary shock is launched into the walls of the tunnel and the progress of this shock into the PMMA block preserves a continuous record of the primary shock's velocity as it travels the length of the tunnel. The density gradient associated with the shock in the PMMA is recorded using dark field shadowgraphy on a SIM-8 multi-channel high speed framing camera. The tunnel shock velocity is determined from the shape of the shock launched into the PMMA block for any time prior to the instant at which the image frame was taken, providing documentation of any oscillations in the velocity of the shock.

  4. DIFFUSIVE SHOCK ACCELERATION OF HIGH-ENERGY CHARGED PARTICLES AT FAST INTERPLANETARY SHOCKS: A PARAMETER SURVEY

    SciTech Connect

    Giacalone, Joe

    2015-01-20

    We present results from numerical simulations of the acceleration of solar energetic particles (SEPs) associated with strong, fast, and radially propagating interplanetary shocks. We focus on the phase of the SEP event at the time of the shock passage at 1 AU, which is when the peak intensity at energies below a few MeV is the highest. The shocks in our study start between 2 and 10 solar radii and propagate beyond 1 AU. We study the effect of various shock and particle input parameters, such as the spatial diffusion coefficient, shock speed, solar wind speed, initial location of the shock, and shock deceleration rate, on the total integrated differential intensity, I, of SEPs with kinetic energies > 10 MeV. I is the integral over energy of the differential intensity spectrum at the time of the shock passage at 1 AU. We find that relatively small changes in the parameters can lead to significant event-to-event changes in I. For example, a factor of 2 increase in the diffusion coefficient at a given energy and spatial location, can lead to a decrease in I by as much as a factor of 50. This may help explain why there are fewer large SEP events seen during the current solar maximum compared to previous maxima. It is known that the magnitude of the interplanetary magnetic field is noticeably weaker this solar cycle than it was in the previous cycle and this will naturally lead to a somewhat larger diffusion coefficient of SEPs.

  5. High-Energy Emission at Shocks in Millisecond Pulsar Binaries

    NASA Astrophysics Data System (ADS)

    Kust Harding, Alice; Wadiasingh, Zorawar; Venter, Christo; Boettcher, Markus

    2016-04-01

    A large number of new Black Widow (BW) and Redback (RB) energetic millisecond pulsars have been discovered through radio searches of unidentified Fermi sources, increasing the known number of these systems from 4 to 28. We model the high-energy emission components from particles accelerated to several TeV in intrabinary shocks in BW and RB systems, and their predicted modulation at the binary orbital period. Synchrotron emission is expected at X-ray energies and such modulated emission has already been detected by Chandra and XMM. Inverse Compton emission from accelerated particles scattering the UV emission from the radiated companion star is expected in the Fermi and TeV bands. Detections or constraints on this emission will probe the unknown physics of pulsar winds.

  6. Development of Ultra Small Shock Tube for High Energy Molecular Beam Source

    NASA Astrophysics Data System (ADS)

    Miyoshi, Nobuya; Nagata, Shuhei; Kinefuchi, Ikuya; Shimizu, Kazuya; Takagi, Shu; Matsumoto, Yoichiro

    2008-12-01

    A molecular beam source exploiting a small shock tube is described for potential generation of high energy beam in a range of 1-5 eV without any undesirable impurities. The performance of a non-diaphragm type shock tube with an inner diameter of 2 mm was evaluated by measuring the acceleration and attenuation process of shock waves. With this shock tube installed in a molecular beam source, we measured the time-of-flight distributions of shock-heated beams, which demonstrated the ability of controlling the beam energy with the initial pressure ratio of the shock tube.

  7. Development of Ultra Small Shock Tube for High Energy Molecular Beam Source

    SciTech Connect

    Miyoshi, Nobuya; Nagata, Shuhei; Kinefuchi, Ikuya; Shimizu, Kazuya; Matsumoto, Yoichiro; Takagi, Shu

    2008-12-31

    A molecular beam source exploiting a small shock tube is described for potential generation of high energy beam in a range of 1-5 eV without any undesirable impurities. The performance of a non-diaphragm type shock tube with an inner diameter of 2 mm was evaluated by measuring the acceleration and attenuation process of shock waves. With this shock tube installed in a molecular beam source, we measured the time-of-flight distributions of shock-heated beams, which demonstrated the ability of controlling the beam energy with the initial pressure ratio of the shock tube.

  8. Gamma-ray burst high energy emission from internal shocks

    NASA Astrophysics Data System (ADS)

    Galli, A.; Guetta, D.

    2008-03-01

    Aims:In this paper we study synchrotron and synchrotron self Compton (SSC) emission from internal shocks (IS) during the prompt and X-ray flare phases of gamma-ray bursts (GRBs). The aim is to test the IS model for the flare emission and for whether GRBs can be GeV sources. Methods: We determine the parameters for which the IS model can account for the observed prompt and X-ray flares emission, and study the detectability of the high energy SSC emission by the AGILE and GLAST satellites. Results: We find that the detectability of the SSC emission during the prompt phase of GRBs improves for higher values of the fireball Lorentz factor Γ and of the temporal variability t_v. If IS is the mechanism responsible for the flare emission, and the Lorentz factor of the shells producing the flare is Γ 100, the flare light curves are expected to present some substructures with temporal variability tv = 10-100 ms which are much smaller than the average duration of flares, and similar to those observed during the prompt phase of GRBs. If one assumes lower Lorentz factors, such as Γ 10 div 25, then a larger temporal variability tv 40 s can also account for the observed flare properties. However in this case we predict that X-ray flares do not have a counterpart at very high energies (MeV-GeV). Conclusions: An investigation on the substructures of the X-ray flare light curves, and simultaneous X-ray and high energy observations, will allow us to corroborate the hypothesis that late IS are responsible for the X-ray flares.

  9. Shock Initiation of Hexanitrostilbene at Ultra-high Shock Pressures and Critical Energy Determination

    NASA Astrophysics Data System (ADS)

    Bowden, Mike; Maisey, Matthew

    2011-06-01

    Hexanitrostilbene is a secondary explosive with attractive properties for detonator usage, including thermal stability, good safety properties and easy initiability. It is desirable to characterize the shock initiation of detonator explosives to enable optimization of system parameters. HNS is a suitable explosive for use in electrical and optical slapper detonators, where shock pressures generated by the flyer plates used can exceed 30 GPa. This extreme shock regime can be explored by initiating HNS with a variety of flyer thicknesses, from 3 to 25 microns at velocities of several km/s. Thresholds for optical and electrical slapper detonators were evaluated, and Photonic Doppler Velocimetery used to determine the flyer velocity at threshold. The flyer diameters are in excess of the critical diameter for HNS, allowing a one-dimensional treatment of the initiation. Calculated values for pressure and shock duration are used to evaluate the critical energy criteria Pn τ . The calculated value of n is compared to published values and discussed for similar systems. The James Criterion is used to analyze the initiation, with values of Ec and Σc being determined from experimental data, providing a predictive capability to model other configurations such as different flyer thicknesses and materials.

  10. Shock initiation of hexanitrostilbene at ultra-high shock pressures and critical energy determination

    NASA Astrophysics Data System (ADS)

    Bowden, Mike; Maisey, Matthew Peter; Knowles, Sarah

    2012-03-01

    Hexanitrostilbene (HNS) is a secondary explosive with attractive properties for detonator usage, including thermal stability, good safety properties and easy initiability. It is desirable to characterize the shock initiation of detonator explosives to enable optimization of system parameters. HNS is a suitable explosive for use in electrical and optical slapper detonators, where shock pressures generated by the flyer plates used can exceed 30 GPa. This extreme shock regime can be explored by initiating HNS with a variety of flyer thicknesses, from 3 to 25 microns at velocities of several km/s. Thresholds for optical and electrical slapper detonators were evaluated, and Photonic Doppler Velocimetery used to determine the flyer velocity at threshold. The flyer diameters are in excess of the critical diameter for HNS, allowing a one-dimensional treatment of the initiation. Calculated values for pressure and shock duration are used to evaluate the critical energy criteria P2τ. The James Criterion is used to analyse the initiation, with values of EC and ΣC being determined from experimental data, providing a predictive capability to model other configurations such as different flyer thicknesses and materials.

  11. Chemistry away from local equilibrium: shocking high-energy and energy absorbing materials

    NASA Astrophysics Data System (ADS)

    Strachan, Alejandro

    2015-06-01

    In this presentation I will describe reactive molecular dynamics and coarse grain simulations of shock induced chemistry. MD simulations of the chemical reactions following the shock-induced collapse of cylindrical pores in the high-energy density material RDX provide the first atomistic picture of the shock to deflagration transition in nanoscale hotspots. We find that energy localization during pore collapse leads to ultra-fast, multi-step chemical reactions that occur under non-equilibrium conditions. The formation of exothermic products during the first few picoseconds of the process prevents the hotspot from quenching, and within 30 ps a deflagration wave develops. Quite surprisingly, an artificial hot-spot matching the shock-induced one in size and thermodynamic conditions quenches; providing strong evidence that the dynamic nature of the loading plays a role in determining the criticality of the hotspot. To achieve time and lengths beyond what is possible in MD we developed a mesoscale model that incorporates chemical reactions at a coarse-grained level. We used this model to explore shock propagation on materials that can undergo volume-reducing, endothermic chemical reactions. The simulations show that such chemical reactions can attenuate the shockwave and characterize how the characteristics of the chemistry affect this behavior. We find that the amount of volume collapse and the activation energy are critical to weaken the shock, whereas the endothermicity of the reactions plays only a minor role. As in the reactive MD simulations, we find that the non-equilibrium state following the shock affects the nucleation of chemistry and, thus, the timescales for equilibration between various degrees of freedom affect the response of the material.

  12. The prompt GRB high energy emission from internal shocks: synchrotron vs inverse Compton component

    SciTech Connect

    Bosnjak, Zeljka; Daigne, Frederic; Dubus, Guillaume

    2009-05-25

    We performed a detailed calculation of gamma-ray burst (GRB) prompt emission in the framework of the internal shock scenario, focusing on the high energy (GeV) bands. In order to follow the evolution of the ultrarelativistic inhomogeneous wind, we combined a model for the dynamics of internal shocks with a detailed calculation of the radiative processes occurring in the shocked medium. We present the resulting synthetic GRB light curves and spectra. We show the spectral evolution that can be expected for different sets of microphysics parameters and parameters of the dynamical evolution, and how the relative importance of synchrotron and inverse Compton components is varying during a burst.

  13. Shock waves in a Z-pinch and the formation of high energy density plasma

    SciTech Connect

    Rahman, H. U.; Wessel, F. J.; Ney, P.; Presura, R.; Ellahi, Rahmat; Shukla, P. K.

    2012-12-15

    A Z-pinch liner, imploding onto a target plasma, evolves in a step-wise manner, producing a stable, magneto-inertial, high-energy-density plasma compression. The typical configuration is a cylindrical, high-atomic-number liner imploding onto a low-atomic-number target. The parameters for a terawatt-class machine (e.g., Zebra at the University of Nevada, Reno, Nevada Terawatt Facility) have been simulated. The 2-1/2 D MHD code, MACH2, was used to study this configuration. The requirements are for an initial radius of a few mm for stable implosion; the material densities properly distributed, so that the target is effectively heated initially by shock heating and finally by adiabatic compression; and the liner's thickness adjusted to promote radial current transport and subsequent current amplification in the target. Since the shock velocity is smaller in the liner, than in the target, a stable-shock forms at the interface, allowing the central load to accelerate magnetically and inertially, producing a magneto-inertial implosion and high-energy density plasma. Comparing the implosion dynamics of a low-Z target with those of a high-Z target demonstrates the role of shock waves in terms of compression and heating. In the case of a high-Z target, the shock wave does not play a significant heating role. The shock waves carry current and transport the magnetic field, producing a high density on-axis, at relatively low temperature. Whereas, in the case of a low-Z target, the fast moving shock wave preheats the target during the initial implosion phase, and the later adiabatic compression further heats the target to very high energy density. As a result, the compression ratio required for heating the low-Z plasma to very high energy densities is greatly reduced.

  14. Ultra-high-energy cosmic rays in a galactic wind and its termination shock

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.; Morfill, G.

    1987-01-01

    Results are reported from numerical modeling of the acceleration and transport of ultra-high-energy cosmic rays in a galactic wind and its termination shock. A two-dimensional (azimuthally symmetric) wind and spiral magnetic field, with a spherical termination shock, where the velocity drops suddenly, is assumed. The time-dependent cosmic-ray transport equation, including all major transport effects is solved using an implicit finite-difference scheme. Particles are injected as the shock of low energy, and the subsequent evolution of the distribution function is followed. Iron nuclei are readily accelerated at the shock to energies up to 100 billion GeV, and protons to 10 billion GeV. A major effect aiding the acceleration of these particles is the spiral of the magnetic field carried out by the wind, caused by the rotation of the Galaxy, with the result that the shock is nearly normal over most of its area. Increasing the magnetic field or rotation rate increases the maximum energy attainable. Anisotropies and energy densities of the particles are also discussed. It is concluded that the process is consistent with observations of ultra-high-energy cosmic rays.

  15. 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].

  16. Dynamics of High Energy Ions at a Structured Collisionless Shock Front

    NASA Astrophysics Data System (ADS)

    Gedalin, M.; Dröge, W.; Kartavykh, Y. Y.

    2016-07-01

    Ions undergoing first-order Fermi acceleration at a shock are scattered in the upstream and downstream regions by magnetic inhomogeneities. For high energy ions this scattering is efficient at spatial scales substantially larger than the gyroradius of the ions. The transition from one diffusive region to the other occurs via crossing the shock, and the ion dynamics during this crossing is mainly affected by the global magnetic field change between the upstream and downstream region. We study the effects of the fine structure of the shock front, such as the foot-ramp-overshoot profile and the phase-standing upstream and downstream magnetic oscillations. We also consider time dependent features, including reformation and large amplitude coherent waves. We show that the influence of the spatial and temporal structure of the shock front on the dependence of the transition and reflection on the pitch angle of the ions is already weak at ion speeds five times the speed of the upstream flow.

  17. Shock-induced decomposition of high energy materials: A ReaxFF molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Tiwari, Subodh; Mishra, Ankit; Nomura, Ken-Ichi; Kalia, Rajiv; Nakano, Aiichiro; Vashishta, Priya

    Atomistic simulations of shock-induced detonation provide critical information about high-energy (HE) materials such as sensitivity, crystallographic anisotropy, detonation velocity, and reaction pathways. However, first principles methods are unable to handle systems large enough to describe shock appropriately. We report reactive-force-field ReaxFF simulations of shock-induced decomposition of 1, 3, 5-triamino-2, 3, 6-trinitrobenzene (TATB) and 1,1-diamino 2-2-dinitroethane (FOX-7) crystal. A flyer acts as mechanical stimuli to introduce a shock, which in turn initiated chemical reactions. Our simulation showed a shock speed of 9.8 km/s and 8.23 km/s for TATB and FOX-7, respectively. Reactivity analysis proves that FOX-7 is more reactive than TATB. Chemical reaction pathways analysis revealed similar pathways for the formation of N2 and H2O in both TATB and FOX-7. However, abundance of NH3 formation is specific to FOX-7. Large clusters formed during the reactions also shows different compositions between TATB and FOX-7. Carbon soot formation is much more pronounced in TATB. Overall, this study provides a detailed comparison between shock induced reaction pathway between FOX-7 and TATB. This work was supported by the Office of Naval Research Grant No. N000014-12-1-0555.

  18. High-energy effective action from scattering of QCD shock waves

    SciTech Connect

    Ian Balitsky

    2005-07-01

    At high energies, the relevant degrees of freedom are Wilson lines - infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops.

  19. High-energy effective action from scattering of QCD shock waves

    SciTech Connect

    Ian Balitsky

    2005-05-15

    At high energies, the relevant degrees of freedom are Wilson lines - infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops.

  20. High-energy effective action from scattering of QCD shock waves

    SciTech Connect

    Ian Balitsky

    2005-10-25

    At high energies, the relevant degrees of freedom are Wilson lines--infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to the projectile and target, includes both up and down fan diagrams and pomeron loops.

  1. High-energy effective action from scattering of QCD shock waves

    SciTech Connect

    Ian Balitsky

    2007-01-01

    At high energies, the relevant degrees of freedom are Wilson lines--infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops.

  2. High-energy effective action from scattering of QCD shock waves

    SciTech Connect

    Ian Balitsky

    2005-06-16

    At high energies, the relevant degrees of freedom are Wilson lines - infinite gauge links ordered along straight lines collinear to the velocities of colliding particles. The effective action for these Wilson lines is determined by the scattering of QCD shock waves. I develop the symmetric expansion of the effective action in powers of strength of one of the shock waves and calculate the leading term of the series. The corresponding first-order effective action, symmetric with respect to projectile and target, includes both up and down fan diagrams and pomeron loops.

  3. HIGH-ENERGY NEUTRINO AND GAMMA-RAY TRANSIENTS FROM TRANS-RELATIVISTIC SUPERNOVA SHOCK BREAKOUTS

    SciTech Connect

    Kashiyama, Kazumi; Gao, Shan; Meszaros, Peter; Murase, Kohta; Horiuchi, Shunsaku

    2013-05-20

    Trans-relativistic shocks that accompany some supernovae (SNe) produce X-ray burst emissions as they break out in the dense circumstellar medium around the progenitors. This phenomenon is sometimes associated with peculiar low-luminosity gamma-ray bursts (LL GRBs). Here, we investigate the high-energy neutrino and gamma-ray counterparts of such a class of SNe. Just beyond the shock breakout radius, particle acceleration in the collisionless shock starts to operate in the presence of breakout photons. We show that protons may be accelerated to sufficiently high energies and produce high-energy neutrinos and gamma rays via the photomeson interaction. These neutrinos and gamma rays may be detectable from {approx}< 10 Mpc away by IceCube/KM3Net as multi-TeV transients almost simultaneously with the X-ray breakout, and even from {approx}< 100 Mpc away with follow-up observations by the Cherenkov Telescope Array using a wide-field sky monitor like Swift as a trigger. A statistical technique using a stacking approach could also be possible for the detection, with the aid of the SN optical/infrared counterparts. Such multi-messenger observations offer the possibility to probe the transition of trans-relativistic shocks from radiation-mediated to collisionless ones, and would also constrain the mechanisms of particle acceleration and emission in LL GRBs.

  4. Formation of reverse shocks in magnetized high energy density supersonic plasma flows

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergey

    2013-10-01

    There has been considerable effort in developing experiments for studies of both collisionless and radiative shocks in high energy density plasmas (HEDP), but there is still very limited experimental information the concerning properties of HEDP shocks in the presence of a magnetic field. A new experimental platform, based on the use of supersonic ablation plasma flows in inverse wire array z-pinches, was developed for studies of shocks in magnetized HEDP plasmas in a well-defined and diagnosable 1-D interaction geometry. The mechanism of flow generation ensures that the plasma flow (MA ~ 5 - 6 , Vflow 100 km/s, ni ~ 1017 cm-3) has a frozen-in magnetic field at a level sufficient to affect the shocks formed in the interaction with conducting obstacles. Experiments show that in addition to the formation of a ``standard'' reverse shock in a stagnated HEDP plasma, the presence of the magnetic field leads to the formation of an additional shock-like feature in the upstream plasma. This shock is triggered by the pile-up of magnetic flux diffusing into the upstream flow, despite a relatively small initial level of the frozen-in magnetic field (the flow ram pressure being much greater than the magnetic field pressure). The thickness of this shock is much smaller than the m.f.p. for the ion-ion collisions, the shock is formed at a distance of ~c/ωpi from the foil and remains stationary for the duration of the experiment (~100 ns). The plasma parameters in the flow and in the shock are measured using optical Thomson scattering, two-color laser interferometry, monochromatic X-ray radiography and miniature magnetic probes. The quantitative data from this experiment, especially the spatial profiles of the density and of the flow velocity measured simultaneously in the upstream and downstream of the shock, will allow detailed verification of MHD and PIC codes used by the HEDP community. Supported by EPSRC Grant EP/G001324/1 and by the OFES under DOE Cooperative Agreement DESC

  5. Modeling of energy transfer in hypersonic shocks using high fidelity models

    NASA Astrophysics Data System (ADS)

    Zhu, Tong

    shock speeds above 9 km/s. High fidelity models for simulating both the dissociation and relaxation processes in N+N2 and N2+N2 systems are also investigated. Relaxation cross sections are computed and the 99 bin method shows good agreement between the bin-to-bin and state specific relaxation cross sections for both N-N2 and N2-N2 relaxation. These relaxation cross sections are then implemented separately in 0D DSMC isothermal relaxation cases. For both cases, the rotational and vibrational temperatures relax to the equilibrium heat bath temperature. For N-N 2 relaxations, the rotational temperature relaxes faster than the vibrational temperature at relatively low translational temperature and at a very similar rate to the vibrational temperature at relatively high temperature. These are in qualitative agreement with the observation of earlier experiments. The one-dimensional binning method and associated cross sections by Parsons et al. are implemented in DSMC simulations and the results are compared with those using the traditional TCE and LB models. For shock conditions similar to those in the experiments of Gorelov, it is found that the MD-QCT chemical reaction model predicts more dissociation and faster relaxation of the vibrational temperature. In the higher speed shock condition of the experiment by Fujita, the use of MD-QCT databases for both chemical reaction and internal energy predicts more dissociation in the downstream of the shock but slower relaxation of the rotational temperature. Also the rotational temperature in the shock region is in somewhat better agreement with the experiment of Fujita.

  6. Electron acceleration to high energies at quasi-parallel shock waves in the solar corona

    NASA Technical Reports Server (NTRS)

    Mann, G.; Classen, H.-T.

    1995-01-01

    In the solar corona shock waves are generated by flares and/or coronal mass ejections. They manifest themselves in solar type 2 radio bursts appearing as emission stripes with a slow drift from high to low frequencies in dynamic radio spectra. Their nonthermal radio emission indicates that electrons are accelerated to suprathermal and/or relativistic velocities at these shocks. As well known by extraterrestrial in-situ measurements supercritical, quasi-parallel, collisionless shocks are accompanied by so-called SLAMS (short large amplitude magnetic field structures). These SLAMS can act as strong magnetic mirrors, at which charged particles can be reflected and accelerated. Thus, thermal electrons gain energy due to multiple reflections between two SLAMS and reach suprathermal and relativistic velocities. This mechanism of accelerating electrons is discussed for circumstances in the solar corona and may be responsible for the so-called 'herringbones' observed in solar type 2 radio bursts.

  7. Hepato-porto-biliary changes following a high energy electrical shock.

    PubMed

    Alnuaimi, Osama; Lazăr, Mihai; Apostolescu, Cătălin; Scheau, Cristian; Adriana Ion, Daniela

    2011-12-24

    Present day increasing dependence on electricity, in both home and work environments, can lead, if the necessary precautions are not met, to a wide type of injuries, from cutaneous burns to important visceral lesions. We report the case of a 44 year-old male with cutaneous and severe visceral lesions, paresis and paresthesia of the right upper limb induced by a high energy electrical shock. No psychiatric manifestations were observed. This case followed an unusual course due to the particular evolution of the hepatic lesions, which included necrosis, abscesses, thrombosis and angiocholitis. PMID:24432255

  8. The formation of reverse shocks in magnetized high energy density supersonic plasma flows

    SciTech Connect

    Lebedev, S. V. E-mail: l.suttle10@imperial.ac.uk; Suttle, L.; Swadling, G. F.; Bennett, M.; Bland, S. N.; Burdiak, G. C.; Chittenden, J. P.; Grouchy, P. de; Hall, G. N.; Hare, J. D.; Kalmoni, N.; Niasse, N.; Patankar, S.; Smith, R. A.; Suzuki-Vidal, F.; Burgess, D.; Clemens, A.; Ciardi, A.; Sheng, L.; Yuan, J.; and others

    2014-05-15

    A new experimental platform was developed, based on the use of supersonic plasma flow from the ablation stage of an inverse wire array z-pinch, for studies of shocks in magnetized high energy density physics plasmas in a well-defined and diagnosable 1-D interaction geometry. The mechanism of flow generation ensures that the plasma flow (Re{sub M} ∼ 50, M{sub S} ∼ 5, M{sub A} ∼ 8, V{sub flow} ≈ 100 km/s) has a frozen-in magnetic field at a level sufficient to affect shocks formed by its interaction with obstacles. It is found that in addition to the expected accumulation of stagnated plasma in a thin layer at the surface of a planar obstacle, the presence of the magnetic field leads to the formation of an additional detached density jump in the upstream plasma, at a distance of ∼c/ω{sub pi} from the obstacle. Analysis of the data obtained with Thomson scattering, interferometry, and local magnetic probes suggests that the sub-shock develops due to the pile-up of the magnetic flux advected by the plasma flow.

  9. Acceleration of High Energy Cosmic Rays in the Nonlinear Shock Precursor

    NASA Astrophysics Data System (ADS)

    Derzhinsky, F.; Diamond, P. H.; Malkov, M. A.

    2006-10-01

    The problem of understanding acceleration of very energetic cosmic rays to energies above the 'knee' in the spectrum at 10^15-10^16eV remains one of the great challenges in modern physics. Recently, we have proposed a new approach to understanding high energy acceleration, based on exploiting scattering of cosmic rays by inhomogenities in the compressive nonlinear shock precursor, rather than by scattering across the main shock, as is conventionally assumed. We extend that theory by proposing a mechanism for the generation of mesoscale magnetic fields (krg<1, where rg is the cosmic ray gyroradius). The mechanism is the decay or modulational instability of resonantly generated Alfven waves scattering off ambient density perturbations in the precursors. Such perturbations can be produced by Drury instability. This mechanism leads to the generation of longer wavelength Alfven waves, thus enabling the confinement of higher energy particles. A simplified version of the theory, cast in the form of a Fokker-Planck equation for the Alfven population, will also be presented. This process also limits field generation on rg scales.

  10. Nonlinear effects in collision cascades and high energy shock waves during ta-C:H growth

    SciTech Connect

    Piazza, F.; Resto, O.; Morell, G.

    2007-07-01

    The surface topography of hydrogenated tetrahedral amorphous carbon (ta-C:H) is critical for various applications such as microelectromechanical devices, magnetic and optical storage devices, and medical implants. The surface topography of ta-C:H films deposited by distributed electron cyclotron resonance plasma from C{sub 2}H{sub 2} gas precursor was investigated. The effects of pressure, together with ion flux and energy, are studied by atomic force microscopy in relation to the structural evolution of the films. The results are compared with the predictions of the Edward-Wilkinson model [Proc. R. Soc. London, Ser. A 44, 1039 (1966)] recently proposed to account for ta-C:H growth and with previous interpretations based on hypersonic shock waves. The random hillocks observed on the smooth surfaces of ta-C:H films deposited at high pressure are thought to result from the interference of high energy shock waves triggered by C{sub 4}H{sub x}{sup +} ions that produce overlapping collision cascades and induce nonlinear effects.

  11. On ultra-high energy cosmic ray acceleration at the termination shock of young pulsar winds

    NASA Astrophysics Data System (ADS)

    Lemoine, Martin; Kotera, Kumiko; Pétri, Jérôme

    2015-07-01

    Pulsar wind nebulae (PWNe) are outstanding accelerators in Nature, in the sense that they accelerate electrons up to the radiation reaction limit. Motivated by this observation, this paper examines the possibility that young pulsar wind nebulae can accelerate ions to ultra-high energies at the termination shock of the pulsar wind. We consider here powerful PWNe, fed by pulsars born with ~ millisecond periods. Assuming that such pulsars exist, at least during a few years after the birth of the neutron star, and that they inject ions into the wind, we find that protons could be accelerated up to energies of the order of the Greisen-Zatsepin-Kuzmin cut-off, for a fiducial rotation period P ~ 1 msec and a pulsar magnetic field Bstar ~ 1013 G, implying a fiducial wind luminosity Lp ~ 1045 erg/s and a spin-down time tsd ~ 3× 107 s. The main limiting factor is set by synchrotron losses in the nebula and by the size of the termination shock; ions with Z>= 1 may therefore be accelerated to even higher energies. We derive an associated neutrino flux produced by interactions in the source region. For a proton-dominated composition, our maximum flux lies slightly below the 5-year sensitivity of IceCube-86 and above the 3-year sensitivity of the projected Askaryan Radio Array. It might thus become detectable in the next decade, depending on the exact level of contribution of these millisecond pulsar wind nebulae to the ultra-high energy cosmic ray flux.

  12. Investigation of efficient shock acceleration of ions using high energy lasers in low density targets

    NASA Astrophysics Data System (ADS)

    Antici, P.; Gauthier, M.; D'Humieres, E.; Albertazzi, B.; Beaucourt, C.; Böker, J.; Chen, S.; Dervieux, V.; Feugeas, J. L.; Glesser, M.; Levy, A.; Nicolai, P.; Romagnani, L.; Tikhonchuk, V.; Pepin, H.; Fuchs, J.

    2012-10-01

    Intense research is being conducted on sources of laser-accelerated ions and their applications that have the potential of becoming novel particle sources. In most experiments, a high intensity and short laser pulse interacts with a solid density target. It was recently shown that a promising way to accelerate ions to higher energies and in a collimated beam is to use under-dense or near-critical density targets instead of solid ones. In these conditions, simulations have revealed that protons are predicted to be accelerated by a collisionless shock mechanism that significantly increases their energy. We present recent experiments performed on the 100 TW LULI laser (France) and the TITAN facility at LLNL, USA. The near critical density plasma was prepared by exploding thin solid foils by a long laser pulse. The plasma density profile was controlled by varying the target thickness and the delay between the long and the short laser pulse. When exploding the target, we obtained proton energies that are comparable if not higher than what was obtained under similar laser conditions, but with solid targets which make them a promising candidate for an efficient proton source.

  13. GENERATION OF HIGH-ENERGY PHOTONS AT ULTRA-RELATIVISTIC SHOCK BREAKOUT IN SUPERNOVAE

    SciTech Connect

    Ohtani, Yukari; Suzuki, Akihiro; Shigeyama, Toshikazu

    2013-11-10

    We present theoretical expectations for non-thermal emission due to the bulk Comptonization at the ultra-relativistic shock breakout. We calculate the transfer of photons emitted from the shocked matter with a Monte Carlo code fully taking into account special relativity. As a hydrodynamical model, we use the self-similar solution of Nakayama and Shigeyama. Our calculations reveal that the spectral shape exhibits a double peak or a single peak depending on the shock temperature at breakout; if it is significantly smaller than the rest energy of an electron, the spectrum has a double peak. We also include a few sample light curves, and estimate the total radiation energy. In comparison with observations of γ-ray bursts, a part of the higher energy component in the spectra and the total energy can be reproduced by some parameter sets. Meanwhile, the lower energy counterpart in the Band function is not reproduced by our results and the duration seems too short to represent an entire γ-ray burst. Therefore the subsequent phase will constitute the lower energy part of the spectrum.

  14. THE HIGH ENERGY BUDGET ALLOCATIONS IN SHOCKS AND GAMMA RAY BURSTS

    SciTech Connect

    Eichler, David; Guetta, Dafne; Pohl, Martin

    2010-10-10

    The statistical distribution of energies among particles responsible for long gamma-ray burst (GRB) emission is analyzed in light of recent results of the Fermi Observatory. The all-sky flux, F{sub {gamma}}, recorded by the Gamma-Ray Burst Monitor (GBM) is shown, despite its larger energy range, to be not significantly larger than that reported by the Burst and Transient Explorer, suggesting a relatively small flux in the 3-30 MeV energy range. The present-day energy input rate in {gamma}-rays recorded by the GBM from long GRBs is found, assuming star formation rates in the literature, to be W-dot(0)=0.5 F{sub {gamma}H}/c=5x10{sup 42}erg Mpc{sup -3} yr{sup -1}. The Large Area Telescope fluence, when observed, is about 5%-10% per decade of the total, in good agreement with the predictions of saturated, nonlinear shock acceleration. The high-energy component of long GRBs, as measured by Fermi, is found to contain only {approx}10{sup -2.5} of the energy needed to produce ultrahigh-energy cosmic rays (UHECRs) above 4 EeV, assuming the latter to be extragalactic, when various numerical factors are carefully included, if the cosmic-ray source spectrum has a spectral index of -2. The observed {gamma}-ray fraction of the required UHECR energy is even smaller if the source spectrum is softer than E {sup -2}. The AMANDA II limits rule out such a GRB origin for UHECRs if much more than 10{sup -2} of the cosmic-ray energy goes into neutrinos that are within, and simultaneous with, the {gamma}-ray beam. It is suggested that 'orphan' neutrinos out of the {gamma}-ray beam might be identifiable via orphan afterglow or other wide angle signatures of GRBs in lieu of coincidence with prompt {gamma}-rays, and it is recommended that feasible single neutrino trigger criteria be established to search for such coincidences.

  15. Electronic energy gap of molecular hydrogen from electrical conductivity measurements at high shock pressures

    NASA Technical Reports Server (NTRS)

    Nellis, W. J.; Mitchell, A. C.; Mccandless, P. C.; Erskine, D. J.; Weir, S. T.

    1992-01-01

    Electrical conductivities were measured for liquid D2 and H2 shock compressed to pressures of 10-20 GPa (100-200 kbar), molar volumes near 8 cu cm/mol, and calculated temperatures of 2900-4600 K. The semiconducting energy gap derived from the conductivities is 12 eV, in good agreement with recent quasi-particle calculations and with oscillator frequencies measured in diamond-anvil cells.

  16. Observation and analysis of emergent coherent structures in a high-energy-density shock-driven planar mixing layer experiment.

    PubMed

    Doss, F W; Flippo, K A; Merritt, E C

    2016-08-01

    Coherent emergent structures have been observed in a high-energy-density supersonic mixing layer experiment. A millimeter-scale shock tube uses lasers to drive Mbar shocks into the tube volume. The shocks are driven into initially solid foam (60 mg/cm^{3}) hemicylinders separated by an Al or Ti metal tracer strip; the components are vaporized by the drive. Before the experiment disassembles, the shocks cross at the tube center, creating a very fast (ΔU> 200 km/s) shear-unstable zone. After several nanoseconds, an expanding mixing layer is measured, and after 10+ ns we observe the appearance of streamwise-periodic, spanwise-aligned rollers associated with the primary Kelvin-Helmholtz instability of mixing layers. We additionally image roller pairing and spanwise-periodic streamwise-aligned filaments associated with secondary instabilities. New closures are derived to connect length scales of these structures to estimates of fluctuating velocity data otherwise unobtainable in the high-energy-density environment. This analysis indicates shear-induced specific turbulent energies 10^{3}-10^{4} times higher than the nearest conventional experiments. Because of difficulties in continuously driving systems under these conditions and the harshness of the experimental environment limiting the usable diagnostics, clear evidence of these developing structures has never before been observed in this regime. PMID:27627387

  17. Observation and analysis of emergent coherent structures in a high-energy-density shock-driven planar mixing layer experiment

    NASA Astrophysics Data System (ADS)

    Doss, F. W.; Flippo, K. A.; Merritt, E. C.

    2016-08-01

    Coherent emergent structures have been observed in a high-energy-density supersonic mixing layer experiment. A millimeter-scale shock tube uses lasers to drive Mbar shocks into the tube volume. The shocks are driven into initially solid foam (60 mg /cm3 ) hemicylinders separated by an Al or Ti metal tracer strip; the components are vaporized by the drive. Before the experiment disassembles, the shocks cross at the tube center, creating a very fast (Δ U > 200 km/s) shear-unstable zone. After several nanoseconds, an expanding mixing layer is measured, and after 10+ ns we observe the appearance of streamwise-periodic, spanwise-aligned rollers associated with the primary Kelvin-Helmholtz instability of mixing layers. We additionally image roller pairing and spanwise-periodic streamwise-aligned filaments associated with secondary instabilities. New closures are derived to connect length scales of these structures to estimates of fluctuating velocity data otherwise unobtainable in the high-energy-density environment. This analysis indicates shear-induced specific turbulent energies 103-104 times higher than the nearest conventional experiments. Because of difficulties in continuously driving systems under these conditions and the harshness of the experimental environment limiting the usable diagnostics, clear evidence of these developing structures has never before been observed in this regime.

  18. Shock Geometry, Seed Populations, and the Origin of Variable Elemental Composition at High Energies in Large Gradual Solar Particle Events

    NASA Astrophysics Data System (ADS)

    Tylka, A. J.; Cohen, C. M. S.; Dietrich, W. F.; Lee, M. A.; Maclennan, C. G.; Mewaldt, R. A.; Ng, C. K.; Reames, D. V.

    2005-05-01

    Above a few tens of MeV per nucleon, large, gradual solar energetic particle (SEP) events are highly variable in their spectral characteristics and elemental composition. The origin of this variability has been a matter of intense and ongoing debate. In this paper, we propose that this variability arises from the interplay of two factors-shock geometry and a compound seed population, typically comprising both solar-wind and flare suprathermals. Whereas quasi-parallel shocks generally draw their seeds from solar-wind suprathermals, quasi-perpendicular shocks-by requiring a higher initial speed for effective injection-preferentially accelerate seed particles from flares. Solar-wind and flare seed particles have distinctive compositional characteristics, which are then reflected in the accelerated particles. We first examine our hypothesis in the context of particles locally accelerated near 1 AU by traveling interplanetary shocks. We illustrate the implications of our hypothesis for SEPs with two very large events, 2002 April 21 and 2002 August 24. These two events arise from very similar solar progenitors but nevertheless epitomize extremes in high-energy SEP variability. We then test our hypothesis with correlation studies based on observations of 43 large SEP events in 1997-2003 by the Advanced Composition Explorer, Wind, the Interplanetary Monitoring Platform 8, and GOES. We consider correlations among high-energy Fe/O, event size, spectral characteristics, the presence of GeV protons, and event duration at high energies. The observed correlations are all qualitatively consistent with our hypothesis. Although these correlation studies cannot be construed as proof of our hypothesis, they certainly confirm its viability. We also examine the alternative hypothesis in which a direct flare component-rather than flare particles subsequently processed through a shock-dominates at high energies. This alternative would produce compositional characteristics similar to

  19. THE LONG AND THE SHORT OF THE HIGH-ENERGY EMISSION IN GRB090926A: AN EXTERNAL SHOCK

    SciTech Connect

    Sacahui, J. R.; Fraija, N.; Gonzalez, M. M.; Lee, W. H. E-mail: nifraija@astro.unam.mx E-mail: wlee@astro.unam.mx

    2012-08-20

    Synchrotron self-Compton (SSC) emission from a reverse shock has been suggested as the origin for the high-energy component lasting 2 s in the prompt phase of GRB98080923. The model describes spectral indices, fluxes, and the duration of the high-energy component as well as a long keV tail present in the prompt phase of GRB980923. Here, we present an extension of this model to describe the high-energy emission of GRB090926A. We argue that the emission consists of two components, one with a duration less than 1 s during the prompt phase, and a second, longer-lasting GeV phase lasting hundred of seconds after the prompt phase. The short high-energy phase can be described as SSC emission from a reverse shock similar to that observed in GRB980923, while the longer component arises from the forward shock. The main assumption is that the jet is magnetized and evolves in the thick-shell case, and the calculated fluxes and break energies are all consistent with the observed values. A comparison between the resulting parameters obtained for GRB980923 and GRB090926A suggests differences in burst tails that could be attributable to the circumburst medium, and this could account for previous analyses reported in the literature for other bursts. We find that the density of the surrounding medium inferred from the observed values associated with the forward shock agrees with standard values for host galaxies such as the one associated with GRB090926A.

  20. Energy of a shock wave generated in different metals under irradiation by a high-power laser pulse

    SciTech Connect

    Gus'kov, S. Yu. Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Skala, J.; Pisarczyk, P.

    2007-10-15

    The energies of a shock wave generated in different metals under irradiation by a high-power laser beam were determined experimentally. The experiments were performed with the use of targets prepared from a number of metals, such as aluminum, copper, silver and lead (which belong to different periods of the periodic table) under irradiation by pulses of the first and third harmonics of the PALS iodine laser at a radiation intensity of approximately 10{sup 14} W/cm{sup 2}. It was found that, for heavy metals, like for light solid materials, the fraction of laser radiation energy converted into the energy of a shock wave under irradiation by a laser pulse of the third harmonic considerably (by a factor of 2-3) exceeds the fraction of laser radiation energy converted under irradiation by a laser pulse of the first harmonic. The influence of radiation processes on the efficiency of conversion of the laser energy into the energy of the shock wave was analyzed.

  1. Quasiperpendicular High Mach Number Shocks.

    PubMed

    Sulaiman, A H; Masters, A; Dougherty, M K; Burgess, D; Fujimoto, M; Hospodarsky, G B

    2015-09-18

    Shock waves exist throughout the Universe and are fundamental to understanding the nature of collisionless plasmas. Reformation is a process, driven by microphysics, which typically occurs at high Mach number supercritical shocks. While ongoing studies have investigated this process extensively both theoretically and via simulations, their observations remain few and far between. In this Letter we present a study of very high Mach number shocks in a parameter space that has been poorly explored and we identify reformation using in situ magnetic field observations from the Cassini spacecraft at 10 AU. This has given us an insight into quasiperpendicular shocks across 2 orders of magnitude in Alfvén Mach number (M_{A}) which could potentially bridge the gap between modest terrestrial shocks and more exotic astrophysical shocks. For the first time, we show evidence for cyclic reformation controlled by specular ion reflection occurring at the predicted time scale of ~0.3τ_{c}, where τ_{c} is the ion gyroperiod. In addition, we experimentally reveal the relationship between reformation and M_{A} and focus on the magnetic structure of such shocks to further show that for the same M_{A}, a reforming shock exhibits stronger magnetic field amplification than a shock that is not reforming. PMID:26430997

  2. Quasiperpendicular High Mach Number Shocks

    NASA Astrophysics Data System (ADS)

    Sulaiman, A. H.; Masters, A.; Dougherty, M. K.; Burgess, D.; Fujimoto, M.; Hospodarsky, G. B.

    2015-09-01

    Shock waves exist throughout the Universe and are fundamental to understanding the nature of collisionless plasmas. Reformation is a process, driven by microphysics, which typically occurs at high Mach number supercritical shocks. While ongoing studies have investigated this process extensively both theoretically and via simulations, their observations remain few and far between. In this Letter we present a study of very high Mach number shocks in a parameter space that has been poorly explored and we identify reformation using in situ magnetic field observations from the Cassini spacecraft at 10 AU. This has given us an insight into quasiperpendicular shocks across 2 orders of magnitude in Alfvén Mach number (MA ) which could potentially bridge the gap between modest terrestrial shocks and more exotic astrophysical shocks. For the first time, we show evidence for cyclic reformation controlled by specular ion reflection occurring at the predicted time scale of ˜0.3 τc , where τc is the ion gyroperiod. In addition, we experimentally reveal the relationship between reformation and MA and focus on the magnetic structure of such shocks to further show that for the same MA , a reforming shock exhibits stronger magnetic field amplification than a shock that is not reforming.

  3. Collisionless shocks driven by 800 nm laser pulses generate high-energy carbon ions

    SciTech Connect

    Zhang, H.; Shen, B. F. Wang, W. P.; Xu, Y.; Liu, Y. Q.; Liang, X. Y.; Leng, Y. X.; Li, R. X. Xu, Z. Z.; Yan, X. Q.; Chen, J. E.

    2015-01-15

    We present experimental studies on ion acceleration from diamond-like carbon (DLC) foils irradiated by 800 nm, linearly polarized laser pulses with peak intensity of 1.7 × 10{sup 19 }W/cm{sup 2} to 3.5 × 10{sup 19 }W/cm{sup 2} at oblique incidence. Diamond-like carbon foils are heated by the prepulse of a high-contrast laser pulse and expand to form plasmas of near-critical density caused by thermal effect before the arrival of the main pulse. It is demonstrated that carbon ions are accelerated by a collisionless shock wave in slightly overdense plasma excited by forward-moving hot electrons generated by the main pulse.

  4. Reduction of high-energy shock-wave-induced renal tubular injury by selenium.

    PubMed

    Strohmaier, W L; Lahme, S; Weidenbach, P M; Bichler, K H

    1999-10-01

    In shock-wave-induced renal injury cavitation-generated free radicals play an important role. Using an in vitro model with Madin-Darby canine kidney (MDCK) cells, we investigated the influence of selenium, a free radical scavenger, in shock-wave-induced tubular cell injury. Suspensions of MDCK cells (33 x 10(6) cells/ml) were placed in small containers (volume 1.1 ml) for shock wave exposure. Two groups of 12 containers each were examined: (1) control (no medication), (2) selenium (0.4 microg/ml nutrient medium). Six containers in each group were exposed to shock waves (impulse rate 256, frequency 60 Hz, generator voltage 18 kV), while the other six containers in each group served as a control. After shock wave exposure, the concentration of cellular enzymes such as lactate dehydrogenase (LDH), N-acetyl-beta-glucosaminidase (NAG), glutamate oxaloacetate transaminase (GOT) and glutamate lactate dehydrogenase (GLDH) in the nutrient medium was examined. Following shock wave exposure there was a significant rise in LDH, NAG, GOT and GLDH concentrations. Selenium reduced this enzyme leakage significantly. Thus we conclude that selenium protects renal tubular cells against shock-wave-induced injury. Since selenium is an essential part of glutathione peroxidase, this effect seems to be mediated by a reduction in reactive oxygen species. PMID:10550528

  5. Contributions from Ultraviolet Spectroscopy to the Prediction of High-energy Proton Hazards from CME Shocks

    NASA Astrophysics Data System (ADS)

    Lin, J.; Raymond, J. C.; Cranmer, S. R.; Kohl, J. L.

    2004-05-01

    A significant potential hazard to astronauts and their equipment in interplanetary space is the relativistic proton flux produced by coronal mass ejections (CMEs) and solar flares. The longest-duration phase of solar energetic particle (SEP) activity is believed to come from the CME shock as it propagates through the extended corona and heliosphere. Ultraviolet spectroscopy by SOHO has revealed a means for: (1) detecting and characterizing CME shocks in the corona, and (2) determining the plasma conditions in the pre-CME corona which are needed to understand the formation and evolution of shocks. Such remote sensing - combined with models of SEP acceleration and transport - can be used to predict the strength, duration, and production sites of the radiation. This poster describes the specific means by which ultraviolet spectroscopy and other remote-sensing data can be used to determine the inputs and boundary conditions for individual events (such as the October-November 2003 storms) in existing SEP model codes. We also discuss an additional potential source of SEP radiation associated with electric fields in the current sheets that form in flare regions in the wake of CME. Both observations and model calculations show that the reconnection-induced electric field can reach a maximum strength of a few V/cm within tens of minutes after the onset of the eruption, then decreases gradually over several hours. SEPs produced in these regions may account for X-rays and γ -rays observed prior to the formation of CME shocks. Ultraviolet spectroscopy has been shown to provide constraints on the plasma properties in all of the above CME features. This work is supported by NASA under grant NAG5-12865 to the Smithsonian Astrophysical Observatory, by Agenzia Spaziale Italiana, and by the Swiss contribution to ESA's PRODEX program.

  6. The High Energy Density science instrument at the European XFEL, Hamburg, Germany: a new platform for shock compression research

    NASA Astrophysics Data System (ADS)

    Appel, Karen; Nakatsutsumi, Motoaki; Priebe, Gerd; Pelka, Alexander; Thorpe, Ian; Tschentscher, Thomas

    2015-06-01

    The High Energy Density science instrument (HED) at the European XFEL, Hamburg, Germany will provide unique experimental possibilities for the investigation of near solid material driven to extreme states and will also establish a new platform to study materials response to shock compression. HED is located at the SASE2 undulator, which provides up to 27000 pulses per second with about 1012 photons per pulse, photon energies between 3 and 24 keV and pulse lengths of 2 - 100 fs. Self-seeding is foreseen, as well as natural bandwidth (BW) SASE radiation. In addition, energy BW of 10-4 and 10-6 will be available through monochromators. Focussing is based on CRL optics, which will allow to provide beam sizes of 2 μm, 10-20 μm and 150 - 260 μm at the sample position. Samples will be driven to extreme states by different types of optical lasers (either 200 kHz/3 mJ/15 fs, 10 Hz/100 TW/30 fs or 10 Hz/100J/ns), the pump-probe FEL beam (delays of up to 2 -23 ps for 5 -20 keV using a split-and-delay unit) and pulsed magnetic fields (up to 50 T). Pump probe experiments can be performed at adapted repetition rates (4.5 MHz, 1 - 10 Hz, single shot). X-ray techniques comprise diffraction, imaging and spectroscopic methods. User operation is planned for fall 2017. We will present the science case of HED, the current layout and present ideas on first shock compression experiments.

  7. High energy neutrino emission and neutrino background from gamma-ray bursts in the internal shock model

    SciTech Connect

    Murase, Kohta; Nagataki, Shigehiro

    2006-03-15

    High energy neutrino emission from gamma-ray bursts (GRBs) is discussed. In this paper, by using the simulation kit GEANT4, we calculate proton cooling efficiency including pion-multiplicity and proton-inelasticity in photomeson production. First, we estimate the maximum energy of accelerated protons in GRBs. Using the obtained results, neutrino flux from one burst and a diffuse neutrino background are evaluated quantitatively. We also take account of cooling processes of pion and muon, which are crucial for resulting neutrino spectra. We confirm the validity of analytic approximate treatments on GRB fiducial parameter sets, but also find that the effects of multiplicity and high-inelasticity can be important on both proton cooling and resulting spectra in some cases. Finally, assuming that the GRB rate traces the star formation rate, we obtain a diffuse neutrino background spectrum from GRBs for specific parameter sets. We introduce the nonthermal baryon-loading factor, rather than assume that GRBs are main sources of ultra-high energy cosmic rays (UHECRs). We find that the obtained neutrino background can be comparable with the prediction of Waxman and Bahcall, although our ground in estimation is different from theirs. In this paper, we study on various parameters since there are many parameters in the model. The detection of high energy neutrinos from GRBs will be one of the strong evidences that protons are accelerated to very high energy in GRBs. Furthermore, the observations of a neutrino background has a possibility not only to test the internal shock model of GRBs but also to give us information about parameters in the model and whether GRBs are sources of UHECRs or not.

  8. Strong shock generation by fast electron energy deposition

    SciTech Connect

    Fox, T. E.; Pasley, J.; Robinson, A. P. L.

    2013-12-15

    It has been suggested that fast electrons may play a beneficial role in the formation of the ignitor shock in shock ignition owing to the high areal density of the fuel at the time of the ignitor pulse. In this paper, we extend previous studies which have focused on monoenergetic electron sources to populations with extended energy distributions. In good agreement with analytic scalings, we show that strong shocks can be produced with peak pressures of a few hundred Mbar to over 1 Gbar using fast electron intensities of 1–10 PW/cm{sup 2} in a uniform deuterium-tritium plasma at 10 g/cm{sup 3}. However, the length required for shock formation increases with fast electron temperature. As this shock formation distance becomes comparable to the target size, the shock is not able to fully develop, and this implies a limit on the ability of fast electrons to aid shock formation.

  9. Prospects for detection of very high-energy emission from GRB in the context of the external shock model

    NASA Astrophysics Data System (ADS)

    Galli, A.; Piro, L.

    2008-10-01

    Context: The detection of the 100 GeV-TeV emission by a gamma-ray burst (GRB) will provide an unprecedented opportunity to study the nature of the central engine and the interaction between the relativistic flow and the environment of the burst's progenitor. Aims: In this paper we show that there are exciting prospects of detecting from the burst by MAGIC high-energy (HE) emission during the early X-ray flaring activity and, later, during the normal afterglow phase. We also identify the best observational strategy: trigger conditions and time period of observation. Methods: We determine the expected HE emission from the flaring and afterglow phases of GRBs in the context of the external shock scenario and compare them with the MAGIC threshold. Results: We find that an X-ray flare with the average properties of the class can be detected in the 100 GeV range by MAGIC, provided that z ≲ 0.7. The requested observational window with MAGIC should then start from 10-20 s after the burst and cover about 1000-2000 s. Furthermore, we demonstrate that there are solid prospects of detecting the late afterglow emission in the same energy range for most of the bursts with z ≲ 0.5 if the density of the external medium is n ≳ a few cm-3. In this case, the MAGIC observation shall extend to about 10-20 ks. We provide recipes for tailoring this prediction to the observational properties of each burst, in particular the fluence in the prompt emission and the redshift, thus allowing an almost real time decision procedure to decide whether to continue the follow-up observation of a burst at late times.

  10. Shock compaction of high- Tc superconductors

    SciTech Connect

    Weir, S.T.; Nellis, W.J.; McCandless, P.C.; Brocious, W.F. ); Seaman, C.L.; Early, E.A.; Maple, M.B. . Dept. of Physics); Kramer, M.J. ); Syono, Y.; Kikuchi, M. )

    1990-09-01

    We present the results of shock compaction experiments on high-{Tc} superconductors and describe the way in which shock consolidation addresses critical problems concerning the fabrication of high J{sub c} bulk superconductors. In particular, shock compaction experiments on YBa{sub 2}Cu{sub 3}O{sub 7} show that shock-induced defects can greatly increase intragranular critical current densities. The fabrication of crystallographically aligned Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} samples by shock-compaction is also described. These experiments demonstrate the potential of the shock consolidation method as a means for fabricating bulk high-{Tc} superconductors having high critical current densities.

  11. Magnetized collisionless shock studies using high velocity plasmoids

    NASA Astrophysics Data System (ADS)

    Weber, Thomas; Intrator, Thomas; Gao, Kevin

    2012-10-01

    Magnetized collisionless shocks are ubiquitous throughout the cosmos and are observed to accelerate particles to relativistic velocities, amplify magnetic fields, transport energy, and create non-thermal distributions. They exhibit transitional scale lengths much shorter than the collisional mean free path and are mediated by collective interactions rather than Coulomb collisions. The Magnetized Shock Experiment (MSX) leverages advances in Field Reversed Configuration (FRC) plasmoid formation and acceleration to produce highly supersonic and super-Alfvènic supercritical shocks with pre-existing magnetic field at perpendicular, parallel or oblique angles to the direction of propagation. Adjustable shock speed, density, and magnetic field provide unique access to a range of parameter space relevant to a variety of naturally occurring shocks. This effort examines experimentally, analytically, and numerically the physics of collisionless shock formation, structure, and kinetic effects in a laboratory setting and draw comparisons between experimental data and astronomical observations. Approved for Public Release: LA-UR-12-22886

  12. Ferrites based infrared radiation coatings with high emissivity and high thermal shock resistance and their application on energy-saving kettle

    NASA Astrophysics Data System (ADS)

    Zhang, Jianyi; Fan, Xi'an; Lu, Lei; Hu, Xiaoming; Li, Guangqiang

    2015-07-01

    Starting from Fe2O3, MnO2, Co2O3 and NiO powders, the ferrites based infrared radiation coatings with high emissivity and high thermal shock resistance were successfully prepared on the surface of carbon steel by high velocity oxy-fuel spraying (HVOF). The coating thickness was about 120-150 μm and presented a typical flat lamellar structure. The coating surface was rough and some submicron grade grains distributed on it. The infrared emissivity of the ferrites based coating by HVOF was over 0.74 in 3-20 μm waveband at 800 °C, which was obviously higher than that of the coating by brushing process in the short waveband. The bonding strength was 30.7 MPa between the coating and substrate, which was five times more than that of conventional coatings by brushing process. The combined effect of the superior bonding strength, typical lamellar structure, pre-existing microcracks and newly generated pores made the cycle times reach 27 when the coating samples were quenched from 1000 °C using water. Lastly, the infrared radiation coatings were applied on the underside of household kettle, and the energy-saving efficiency could reach 30.5%. The ferrites based infrared radiation coatings obtained in this work are good candidates for saving energy in the field of cookware and industrial high temperature furnace.

  13. Heterogeneous Shock Energy Deposition in Shock Wave Consolidation of Metal Powders.

    NASA Astrophysics Data System (ADS)

    Mutz, Andrew Howard

    Shock wave consolidation of powder is a high deformation rate process in which a shock wave generated by an explosive or a colliding projectile rapidly densifies and bonds together the powder particles into a solid compact. The deposition of the shock energy during this process is highly inhomogeneous on the powder particle scale. Evidence of the extent and pattern of the energy deposition was provided by recovery experiments performed using a crystalline metallic glass forming alloy, and analyzed using a heat flow model. The energy deposited during the shock wave passage was best modeled as deposited partly into the particle bulk and partly onto particle surfaces. To investigate this inhomogeneity, and the powder parameters which influence it, a propellant driven gas gun was designed, built and utilized. The planarity of the shock waves produced using the targets designed for the gun was established. Powder - powder thermocouples were impacted with powders of varying sizes to establish the effect of particle size on energy deposition. Small particles in contact with large ones were inferred to absorb the greater fraction of shock energy. Hardened and unhardened steel powder was shocked to investigate the effect of particle hardness on energy distribution. The recovered compacts were not measurably affected by the initial hardness. Compaction experiments were performed on a Ni based super-alloy and on a SiC reinforced Ti matrix composite to test some of the practical applications of the process and the target designs developed. Superior tensile properties were observed in the shock consolidated and heat treated Ni based 718 alloy. The SiC reinforced composite was recovered in the intended net shape with no macro-cracks in the compact body, but with fractured SiC particles.

  14. Internal energy relaxation in shock wave structure

    SciTech Connect

    Josyula, Eswar Suchyta, Casimir J.; Boyd, Iain D.; Vedula, Prakash

    2013-12-15

    The Wang Chang-Uhlenbeck (WCU) equation is numerically integrated to characterize the internal structure of Mach 3 and Mach 5 shock waves in a gas with excitation in the internal energy states for the treatment of inelastic collisions. Elastic collisions are modeled with the hard sphere collision model and the transition rates for the inelastic collisions modified appropriately using probabilities based on relative velocities of the colliding particles. The collision integral is evaluated by the conservative discrete ordinate method [F. Tcheremissine, “Solution of the Boltzmann kinetic equation for high-speed flows,” Comput. Math. Math. Phys. 46, 315–329 (2006); F. Cheremisin, “Solution of the Wang Chang-Uhlenbeck equation,” Dokl. Phys. 47, 487–490 (2002)] developed for the Boltzmann equation. For the treatment of the diatomic molecules, the internal energy modes in the Boltzmann equation are described quantum mechanically given by the WCU equation. As a first step in the treatment of the inelastic collisions by the WCU equation, a two- and three-quantum system is considered to study the effect of the varying of (1) the inelastic cross section and (2) the energy gap between the quantum energy states. An alternative method, the direct simulation Monte Carlo method, is used for the Mach 3 shock wave to ensure the consistency of implementation in the two methods and there is an excellent agreement between the two methods. The results from the WCU implementation showed consistent trends for the Mach 3 and Mach5 standing shock waves simulations. Inelastic contributions change the downstream equilibrium state and allow the flow to transition to the equilibrium state further upstream.

  15. Simulations of high-gain shock-ignited inertial-confinement-fusion implosions using less than 1 MJ of direct KrF-laser energy

    NASA Astrophysics Data System (ADS)

    Bates, Jason W.; Schmitt, Andrew J.; Fyfe, David E.; Obenschain, Steve P.; Zalesak, Steve T.

    2010-06-01

    In this paper, we report on recent numerical simulations of inertial-confinement-fusion (ICF) implosions using the FAST radiation hydrocode at the U.S. Naval Research Laboratory. Our study focuses on three classes of shock-ignited target designs utilizing less than 1 MJ of direct, krypton-fluoride (KrF) laser energy, which was "zoomed" to maximize the coupling efficiency. In the shock-ignition approach [R. Betti, C.D. Zhou, K.S. Anderson, et al., Phys. Rev. Lett. 98 (2007) 155001], a moderate-intensity, compressive laser pulse is followed by a short-duration high-intensity spike that launches a spherically-convergent shock wave to ignite a thick shell of compressed fuel. Such an arrangement appears to offer several significant advantages, including a low ignition threshold, high gain, and less susceptibility to the deleterious effects of hydrodynamic and laser-plasma instabilities. According to one-dimensional simulations, fusion gains over 200 can be achieved with shock-ignited targets using less than 750 kJ of laser energy. This represents a significant improvement in performance over conventional centrally-ignited designs. To examine the stability of these targets, several two-dimensional simulations were also performed that incorporated realistic perturbation sources such as laser imprinting and roughness spectra for inner/outer pellet surfaces. Although the simulations indicate that appreciable low-mode distortion of the fuel shell can occur at late time as a result of these perturbations, high gains are still achieved in many cases owing to the low in-flight aspect ratios of shock-ignited targets. We should remark, though, that the high convergence ratios of these same designs suggest that other sources of low-mode asymmetries, which were not considered in this study (e.g., beam misalignment and energy-balance errors), may be important in determining overall pellet stability and performance. We discuss these issues, as well as other salient design

  16. Turbulent energy generated by accelerations and shocks

    SciTech Connect

    Mikaelian, K.O.

    1986-10-08

    The turbulent energy generated at the interface between two fluids undergoing a constant acceleration or a shock is calculated. Assuming linear density profiles in the mixed region we find E/sub turbulent//E/sub directed/ = 2.3A/sup 2/% (constant acceleration) and 9.3A/sup 2/% (shock), where A is the Atwood number. Diffusion models predict somewhat less turbulent energy and a density profile with a tail extending into the lower density fluid. Eddy sizes are approximately 27% (constant acceleration) and 17% (shock) of the mixing depth into the heavier fluid. 6 refs., 3 figs.

  17. High spatial resolution, high energy synchrotron x-ray diffraction characterization of residual strains and stresses in laser shock peened Inconel 718SPF alloy

    NASA Astrophysics Data System (ADS)

    Gill, Amrinder S.; Zhou, Zhong; Lienert, Ulrich; Almer, Jonathan; Lahrman, David F.; Mannava, S. R.; Qian, Dong; Vasudevan, Vijay K.

    2012-04-01

    Laser shock peening (LSP) is an advanced surface enhancement technique used to enhance the fatigue strength of metal parts by imparting deep compressive residual stresses. In the present study, LSP was performed on IN718 SPF alloy, a fine grained nickel-based superalloy, with three different power densities and depth resolved residual strain and stress characterization was conducted using high energy synchrotron x-ray diffraction in beam line 1-ID-C at the Advanced Photon Source at the Argonne National laboratory. A fine probe size and conical slits were used to non-destructively obtain data from specific gauge volumes in the samples, allowing for high-resolution strain measurements. The results show that LSP introduces deep compressive residual stresses and the magnitude and depth of these stresses depend on the energy density of the laser. The LSP induced residual stresses were also simulated using three-dimensional nonlinear finite element analysis, with employment of the Johnson-Cook model for describing the nonlinear materials constitutive behavior. Good agreement between the experimental and simulated data was obtained. These various results are presented and discussed.

  18. Turbulent energy flux generated by shock/homogeneous-turbulence interaction

    NASA Astrophysics Data System (ADS)

    Sinha, Krishnendu; Quadros, Russell; Larsson, Johan

    2015-11-01

    High-speed turbulent flows with shock waves are characterized by high localized surface heat transfer rates. Computational predictions are often inaccurate due to the limitations in modeling of the unclosed turbulent energy flux in the highly non-equilibrium regions of shock interaction. In this paper, we investigate the turbulent energy flux generated when homogeneous isotropic turbulence passes through a nominally normal shock wave. We use linear interaction analysis where the incoming turbulence is idealized as being composed of a collection of two-dimensional planar vorticity waves, and the shock wave is taken to be a discontinuity. The nature of the post-shock turbulent energy flux is predicted to be strongly dependent on the incidence angle of the incoming waves. The energy flux correlation is also decomposed into its vortical, entropy and acoustic contributions to understand its rapid non-monotonic variation behind the shock. Three-dimensional statistics, calculated by integrating two-dimensional results over a prescribed upstream energy spectrum, are compared with available direct numerical simulation data. A detailed budget of the governing equation is also considered in order to gain insight into the underlying physics.

  19. 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.

  20. 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.

  1. Validating density-functional theory simulations at high energy-density conditions with liquid krypton shock experiments to 850 GPa on Sandia's Z machine

    SciTech Connect

    Mattsson, Thomas R.; Root, Seth; Mattsson, Ann E.; Shulenburger, Luke; Magyar, Rudolph J.; Flicker, Dawn G.

    2014-11-11

    We use Sandia's Z machine and magnetically accelerated flyer plates to shock compress liquid krypton to 850 GPa and compare with results from density-functional theory (DFT) based simulations using the AM05 functional. We also employ quantum Monte Carlo calculations to motivate the choice of AM05. We conclude that the DFT results are sensitive to the quality of the pseudopotential in terms of scattering properties at high energy/temperature. A new Kr projector augmented wave potential was constructed with improved scattering properties which resulted in excellent agreement with the experimental results to 850 GPa and temperatures above 10 eV (110 kK). In conclusion, we present comparisons of our data from the Z experiments and DFT calculations to current equation of state models of krypton to determine the best model for high energy-density applications.

  2. Validating density-functional theory simulations at high energy-density conditions with liquid krypton shock experiments to 850 GPa on Sandia's Z machine

    DOE PAGESBeta

    Mattsson, Thomas R.; Root, Seth; Mattsson, Ann E.; Shulenburger, Luke; Magyar, Rudolph J.; Flicker, Dawn G.

    2014-11-11

    We use Sandia's Z machine and magnetically accelerated flyer plates to shock compress liquid krypton to 850 GPa and compare with results from density-functional theory (DFT) based simulations using the AM05 functional. We also employ quantum Monte Carlo calculations to motivate the choice of AM05. We conclude that the DFT results are sensitive to the quality of the pseudopotential in terms of scattering properties at high energy/temperature. A new Kr projector augmented wave potential was constructed with improved scattering properties which resulted in excellent agreement with the experimental results to 850 GPa and temperatures above 10 eV (110 kK). Inmore » conclusion, we present comparisons of our data from the Z experiments and DFT calculations to current equation of state models of krypton to determine the best model for high energy-density applications.« less

  3. Symmetry of spherically converging shock waves through reflection, relating to the shock ignition fusion energy scheme.

    PubMed

    Davie, C J; Evans, R G

    2013-05-01

    We examine the properties of perturbed spherically imploding shock waves in an ideal fluid through the collapse, bounce, and development into an outgoing shock wave. We find broad conservation of the size and shape of ingoing and outgoing perturbations when viewed at the same radius. The outgoing shock recovers the velocity of the unperturbed shock outside the strongly distorted core. The results are presented in the context of the robustness of the shock ignition approach to inertial fusion energy. PMID:23683207

  4. Condensed matter at high shock pressures

    SciTech Connect

    Nellis, W.J.; Holmes, N.C.; Mitchell, A.C.; Radousky, H.B.; Hamilton, D.

    1985-07-12

    Experimental techniques are described for shock waves in liquids: Hugoniot equation-of-state, shock temperature and emission spectroscopy, electrical conductivity, and Raman spectroscopy. Experimental data are reviewed and presented in terms of phenomena that occur at high densities and temperatures in shocked He, Ar, N/sub 2/, CO, SiO/sub 2/-aerogel, H/sub 2/O, and C/sub 6/H/sub 6/. The superconducting properties of Nb metal shocked to 100 GPa (1 Mbar) and recovered intact are discussed in terms of prospects for synthesizing novel, metastable materials. Ultrahigh pressure data for Cu is reviewed in the range 0.3 to 6TPa (3 to 60 Mbar). 56 refs., 9 figs., 1 tab.

  5. Comminution of solids caused by kinetic energy of high shear strain rate, with implications for impact, shock, and shale fracturing

    PubMed Central

    Bažant, Zdeněk P.; Caner, Ferhun C.

    2013-01-01

    Although there exists a vast literature on the dynamic comminution or fragmentation of rocks, concrete, metals, and ceramics, none of the known models suffices for macroscopic dynamic finite element analysis. This paper outlines the basic idea of the macroscopic model. Unlike static fracture, in which the driving force is the release of strain energy, here the essential idea is that the driving force of comminution under high-rate compression is the release of the local kinetic energy of shear strain rate. The density of this energy at strain rates >1,000/s is found to exceed the maximum possible strain energy density by orders of magnitude, making the strain energy irrelevant. It is shown that particle size is proportional to the −2/3 power of the shear strain rate and the 2/3 power of the interface fracture energy or interface shear stress, and that the comminution process is macroscopically equivalent to an apparent shear viscosity that is proportional (at constant interface stress) to the −1/3 power of this rate. A dimensionless indicator of the comminution intensity is formulated. The theory was inspired by noting that the local kinetic energy of shear strain rate plays a role analogous to the local kinetic energy of eddies in turbulent flow. PMID:24218624

  6. Proton shock acceleration using a high contrast high intensity laser

    NASA Astrophysics Data System (ADS)

    Gauthier, Maxence; Roedel, Christian; Kim, Jongjin; Aurand, Bastian; Curry, Chandra; Goede, Sebastian; Propp, Adrienne; Goyon, Clement; Pak, Art; Kerr, Shaun; Ramakrishna, Bhuvanesh; Ruby, John; William, Jackson; Glenzer, Siegfried

    2015-11-01

    Laser-driven proton acceleration is a field of intense research due to the interesting characteristics of this novel particle source including high brightness, high maximum energy, high laminarity, and short duration. Although the ion beam characteristics are promising for many future applications, such as in the medical field or hybrid accelerators, the ion beam generated using TNSA, the acceleration mechanism commonly achieved, still need to be significantly improved. Several new alternative mechanisms have been proposed such as collisionless shock acceleration (CSA) in order to produce a mono-energetic ion beam favorable for those applications. We report the first results of an experiment performed with the TITAN laser system (JLF, LLNL) dedicated to the study of CSA using a high intensity (5x1019W/cm2) high contrast ps laser pulse focused on 55 μm thick CH and CD targets. We show that the proton spectrum generated during the interaction exhibits high-energy mono-energetic features along the laser axis, characteristic of a shock mechanism.

  7. Shock properties of high-strength ceramics

    SciTech Connect

    Grady, D.E.

    1994-12-31

    A broad class of brittle solids subjected to large amplitude shock waves can support substantial shear stress (of order 2-10 GPa) without failing due to the very limited slip systems in these materials. When failure occurs under sufficiently intense shock loading, the effect is usually observed as a wave splitting in the compressive shock front. Because of the high confining stress state associated with the failure event in the shock compression environment, it is no longer certain whether the microstructural processes of deformation are brittle or ductile. Some, although by no means sufficient, evidence supports a brittle deformation mechanism in the materials of interest. The present short paper focuses on two aspects of the transition regime neighboring the HEL in the compressive shock process. First, issues of rate dependence associated with prompt yield under shock compression are not well understood. We report here on observations of wave profile data on ceramics, examining he issue of elastic precursor decay. Also in this study, a number of the experimental observations of failure waves in ceramic materials (principally glass) are surveyed. Some of the principal results are summarized and dynamic failure mechanisms consistent with these results are discussed.

  8. Magnetized Collisionless Shock Studies Using High Velocity Plasmoids

    NASA Astrophysics Data System (ADS)

    Weber, Thomas; Intrator, T.

    2013-04-01

    Magnetized collisionless shocks are ubiquitous throughout the cosmos and are observed to accelerate particles to relativistic velocities, amplify magnetic fields, transport energy, and create non-thermal distributions. They exhibit transitional scale lengths much shorter than the collisional mean free path and are mediated by collective interactions rather than Coulomb collisions. The Magnetized Shock Experiment (MSX) leverages advances in Field Reversed Configuration (FRC) plasmoid formation and acceleration to produce highly supersonic and super-Alfvénic supercritical shocks with pre-existing magnetic field at perpendicular, parallel or oblique angles to the direction of propagation. Adjustable shock speed, density, and magnetic field provide unique access to a range of parameter space relevant to a variety of naturally occurring shocks. This effort examines experimentally, analytically, and numerically the physics of collisionless shock formation, structure, and kinetic effects in a laboratory setting and draw comparisons between experimental data and astronomical observations. Supported by DOE Office of Fusion Energy Sciences and National Nuclear Security Administration under LANS contract DE-AC52-06NA25369 Approved for Public Release: LA-UR-12-22886

  9. Magnetized collisionless shock studies using high velocity plasmoids

    NASA Astrophysics Data System (ADS)

    Weber, T.; Intrator, T.; Gao, K.

    2012-12-01

    Magnetized collisionless shocks are ubiquitous throughout the cosmos and are observed to accelerate particles to relativistic velocities, amplify magnetic fields, transport energy, and create non-thermal distributions. They exhibit transitional scale lengths much shorter than the collisional mean free path and are mediated by collective interactions rather than Coulomb collisions. The Magnetized Shock Experiment (MSX) leverages advances in Field Reversed Configuration (FRC) plasmoid formation and acceleration to produce highly supersonic and super-Alfvènic supercritical shocks with pre-existing magnetic field at perpendicular, parallel or oblique angles to the direction of propagation. Adjustable shock speed, density, and magnetic field provide unique access to a range of parameter space relevant to a variety of naturally occurring shocks. This effort examines experimentally, analytically, and numerically the physics of collisionless shock formation, structure, and kinetic effects in a laboratory setting and draw comparisons between experimental data and astronomical observations. Supported by DOE Office of Fusion Energy Sciences and National Nuclear Security Administration under LANS contract DE-AC52-06NA25369 Approved for Public Release: LA-UR-12-22886

  10. Dynamic Theory: some shock wave and energy implications

    SciTech Connect

    Williams, P.E.

    1981-02-01

    The Dynamic Theory, a unifying five-dimensional theory of space, time, and matter, is examined. The theory predicts an observed discrepancy between shock wave viscosity measurements at low and high pressures in aluminum, a limiting mass-to-energy conversion rate consistent with the available data, and reduced pressures in electromagneticaly contained controlled-fusion plasmas.

  11. Macroeconomic impacts of energy shocks: an overview

    SciTech Connect

    Not Available

    1984-03-23

    Through a comparison of existing models of the US economy, this study evaluates the likely short- to medium-term effects of energy price changes on inflation, unemployment, and economic growth. It focuses on the impacts during the four years immediately following the energy price change. During this period, the economy's adjustment may still be unfolding and not yet complete. The working group studied 10 scenarios simulated by 14 participating modelers. We identified several prominent conclusions relating to the impacts of a shock, the efficacy of different economic policies, energy policy considerations, and key characteristics of the participating models.

  12. High energy ions and electrons upstream from the Earth's bow shock and their dependence on geomagnetic conditions: Statistical results between years 1982-1988

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Kaliabetsos, G.; Argyropoulos, G.; Sarris, E. T.

    We present initial results from a statistical analysis of 2034 energetic (50-220 keV) ion events observed by the IMP-8 spacecraft upstream from the Earth’s bow shock during a 6 years period. The most important findings are the following: (1) the percentage Pe of high intensity energetic ion events accompanied by the presence of relativistic (≥ 220 keV) electrons is ˜80% (for all geomagnetic conditions), and increases significantly with increasing the index Kp of geomagnetic activity, (2) high intensity energetic ion events most often (˜93%) show spectra extending up to energies E>˜300 keV, (3) a percentage of ˜71.5% of events display non-inverse energy dispersion of ion intensities. The above results, as well as additional results discussed in the text, suggest that a percentage as high as ˜80% of high intensity 50-220 keV ion events in our statistical sample have an origin within the magnetosphere.

  13. Vibrational energy transfer and quenching of OH A{sup 2}{Sigma}{sup +}({nu}{prime}=1) measured at high temperatures in a shock tube

    SciTech Connect

    Paul, P.H.

    1995-05-25

    Rate coefficients are reported for vibrational energy transfer and electronic quenching of OH A{sup 2}{Sigma}{sup +}({nu}{prime}=1) by N{sub 2}, O{sub 2}, CO, CO{sub 2}, NO, Ar, Kr, and Xe. Rate coefficients for electronic quenching of OH A{sup 2}{Sigma}{sup +}({nu}{prime}=0) by the same set of collision partners are also reported. The measurements were performed at high temperatures (1900 and 2300 K) behind reproducible shock waves. The cross sections for quenching in {nu}{prime} = 1 were observed to be quite similar to the values found for quenching in {nu}{prime} = 0. For all of the species studied, the cross sections were found to be independent of temperature from 1900 to 2300 K. However, all of the high-temperature cross sections were found to be smaller than the previously reported values for quenching and vibrational energy transfer at 300 K. The decrease in the cross sections with temperature was observed to be more pronounced for vibrational energy transfer than for electronic quenching. 33 refs., 3 tabs.

  14. Gamma-ray emission from globular clusters. Shock high energy emission from the Be-Star/Pulsar System PSR 1259-63. Echoes in x-ray novae

    NASA Technical Reports Server (NTRS)

    Kaaret, Philip

    1995-01-01

    This grant covers work on the Compton phase 3 investigation, 'Shock High Energy Emission from the Be- Star/Pulsar System PSR 1259-63' and cycle 4 investigations 'Diffuse Gamma-Ray Emission at High Latitudes' and 'Echoes in X-Ray Novae'. Work under the investigation 'Diffuse Gamma-Ray Emission at High Latitudes' has lead to the publication of a paper (attached), describing gamma-ray emissivity variations in the northern galactic hemisphere. Using archival EGRET data, we have found a large irregular region of enhanced gamma-ray emissivity at energies greater 100 MeV. This is the first observation of local structure in the gamma-ray emissivity. Work under the investigation 'Echoes in X-Ray Novae' is proceeding with analysis of data from OSSE from the transient source GRO J1655-40. The outburst of this source last fall triggered this Target of Opportunity investigation. Preliminary spectral analysis shows emission out to 600 keV and a pure power low spectrum with no evidence of an exponential cutoff. Work is complete on the analysis of BATSE data from the Be-Star/Pulsar Sustem PSR 1259-63.

  15. Generation of laser plasma bunches with a high efficiency of energy concentration for laboratory simulation of collisionless shock waves in magnetised cosmic plasma

    NASA Astrophysics Data System (ADS)

    Zakharov, Yu P.; Ponomarenko, A. G.; Tishchenko, V. N.; Antonov, V. M.; Melekhov, A. V.; Posukh, V. G.; Prokopov, P. A.; Terekhin, V. A.

    2016-05-01

    We present the results of first experiments on the formation of collisionless shock waves (CSWs) in background plasma by injecting laser plasma bunches transverse to the magnetic field (as a piston) with a maximum energy up to 100 J per unit of solid angle and with a high enough degree of ion magnetisation. With this aim in view, on a unique KI-1 facility at the Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences (ILP), a plastic (polyethylene) target irradiated by a CO2 laser in the most energy-efficient regime (near the plasma formation threshold) and a highly ionised hydrogen plasma with a high concentration in a large volume (not less than 1 m3) have been employed. As a result of model experiments performed on the basis of a model of collisionless interaction of plasma flows, developed at the VNIIEF and being adequate to the problem under consideration, not only an intensive, background-induced, deceleration of a super-Alfven laser plasma flow, but also the formation in that flow of a strong perturbation having the properties of a subcritical CSW and propagating transverse to the magnetic field, have been first registered in the laboratory conditions.

  16. Energy Dissipation at a Shock Front in Diamond: Simulation and Comparison with Phase Contrast Imaging Data

    NASA Astrophysics Data System (ADS)

    Beckwith, Martha; Schropp, Andreas; Ping, Yuan; Swift, Damian; Collins, Gilbert

    2015-06-01

    Understanding the behavior of carbon at high pressures and temperatures is essential for predicting the structure and evolution of giant planets, such as Uranus and Neptune. Shock compression experiments on pure carbon materials, such as diamond, can provide insight into their behavior at the extreme temperatures and pressures of the giant planets. Phase contrast imaging and hydrodynamic simulations were used to examine the propagation of a shock front in diamond. As the shock front propagates through the sample, a decrease in the shock amplitude and an increase in the shock width are observed, indicating that energy dissipative processes, such as viscosity, are apparent. In addition, fractures are observed in the diamond sample behind the shock, which could also contribute to the energy dissipation at the shock front. Work at LLNL performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Mechanochemistry for Shock Wave Energy Dissipation

    NASA Astrophysics Data System (ADS)

    Shaw, William; Ren, Yi; Su, Zhi; Moore, Jeffrey; Suslick, Kenneth; Dlott, Dana

    2015-06-01

    Using our laser-driven flyer-plate apparatus we have developed a technique for detecting mechanically driven chemical reactions that attenuate shock waves. In these experiments 75 μm laser-driven flyer-plates travel at speeds of up to 2.8 km/s. Photonic Doppler velocimetry is used to monitor both the flight speed and the motions of an embedded mirror behind the sample on the supporting substrate. Since the Hugoniot of the substrate is known, mirror motions can be converted into the transmitted shock wave flux and fluence through a sample. Flux shows the shock profile whereas fluence represents the total energy transferred per unit area, and both are measured as a function of sample thickness. Targets materials are micrograms of carefully engineered organic and inorganic compounds selected for their potential to undergo negative volume, endothermic reactions. In situ fluorescence measurements and a suite of post mortem analytical methods are used to detect molecular chemical reactions that occur due to impact.

  18. High Throughput Screen for Escherichia coli Heat Shock Protein 70 (Hsp70/DnaK): ATPase Assay in Low Volume By Exploiting Energy Transfer

    PubMed Central

    Miyata, Yoshinari; Chang, Lyra; Bainor, Anthony; McQuade, Thomas J.; Walczak, Christopher P.; Zhang, Yaru; Larsen, Martha J.; Kirchhoff, Paul; Gestwicki, Jason E.

    2011-01-01

    Members of the heat shock protein 70 (Hsp70) family of molecular chaperones are emerging as potential therapeutic targets. Their ATPase activity has classically been measured using colorimetric phosphate-detection reagents, such as quinaldine red (QR). While such assays are suitable for 96-well plate formats, they typically lose sensitivity when attempted in lower volume due to path length and meniscus effects. These limitations and Hsp70’s weak enzymatic activity have combined to create significant challenges in high throughput screening. To overcome these difficulties, we have adopted an energy transfer strategy that was originally reported by Zuck et al. (Anal. Biochem. 2005, 342:254–259). Briefly, white 384-well plates emit fluorescence when irradiated at 430 nm. In turn, this intrinsic fluorescence can be quenched by energy transfer with the QR-based chromophore. Using this more sensitive approach, we tested 55,400 compounds against DnaK, a prokaryotic member of the Hsp70 family. The assay performance was good (Z′ ~ 0.6, CV ~8%) and at least one promising new inhibitor was identified. In secondary assays, this compound specifically blocked stimulation of DnaK by its co-chaperone, DnaJ. Thus, this simple and inexpensive adaptation of a colorimetric method might be suitable for screening against Hsp70-family members. PMID:20926844

  19. Shock ignition target design for inertial fusion energy

    NASA Astrophysics Data System (ADS)

    Schmitt, Andrew J.; Bates, Jason W.; Obenschain, Steven P.; Zalesak, Steven T.; Fyfe, David E.

    2010-04-01

    Continuing work in the design of shock ignition targets is described. Because of reduced implosion velocity requirements, low target adiabats, and efficient drive by short wavelength lasers, these targets produce high gain (>100) at laser energies well below 1 MJ. Effects of hydrodynamic instabilities such as Rayleigh-Taylor or Richtmyer-Meshkov are greatly reduced in these low-aspect ratio targets. Of particular interest is the optimum ratio of ignitor to compression pulse energy. A simple pellet model and simulation-derived coupling coefficients are used to analyze optimal fuel assembly, and determine that shock ignition allows enough control to create theoretically optimum assemblies. The effects on target design due to constraints on the compression and ignitor pulse intensities are also considered and addressed. Significant sensitivity is observed from low-mode perturbations because of large convergence ratios, but a more powerful ignitor can mitigate this.

  20. High Bandwidth Differential Amplifier for Shock Experiments

    SciTech Connect

    Ross, P. W., Tran, V., Chau, R.

    2012-04-30

    We developed a high bandwidth differential amplifier for gas gun shock experiments/applications. The circuit has a bandwidth > 1 GHz, and is capable of measuring signals of ≤1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. High pass filters suppress internal ringing of operational amplifiers. Results of bench tests are shown.

  1. Ion heating and energy redistribution across supercritical perpendicular shocks: Application to planetary and interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Liu, Y. D.; Richardson, J. D.; Parks, G. K.

    2013-12-01

    We investigate how the ion dissipative process across supercritical perpendicular shocks depends on the shock front micro-structures. At a collisionless plasma shock, the dissipation and micro-structure of the shock font are dominated by wave-particle interactions. Comparison of the ion thermalization at different kinds of shocks, e.g., planetary and interplanetary shocks, can quantify how much interaction is occurring at the shock boundary. Investigation of this problem for diverse solar wind (SW) conditions will yield important information on the dependences of the ion thermalization and energy redistribution on plasma parameters. With the aid of a successful automatic separation method [Yang et al., 2009], the incident ions at the shock can be divided into two parts: reflected (R) ions and directly transmitted (DT) ions. Corresponding heating efficiency of each population of ions at the shock can be calculated respectively. Wilkinson & Schwartz [1990] have theorized that the amount of reflected ions at perpendicular shocks depends on plasma parameters. Based on the Rankine-Hugoniot (R-H) conservation laws, they found that the fraction reflected is strongly dependent on the magnitude of the ratio of specific heat capacities γ chosen in the R-H relations. The main goal of this work is to investigate how the plasma parameters, e.g. the particle velocity distribution, the plasma beta value, seed populations, etc. (from a particle dynamic point of view), control the amount of reflected ions by using one-dimensional (1-D) full-particle-cell simulations. The simulation results may help to explain the ion heating efficiency and energy redistribution at shocks observed by Cluster, Wind, Voyager, etc.

  2. High Bandwidth Differential Amplifier for Shock Experiments

    SciTech Connect

    Ross, P., Tran, V., Chau, R.

    2012-10-01

    We developed a high bandwidth differential amplifier for gas gun shock experiments. The circuit has a bandwidth up to 1 GHz, and is capable of measuring signals of ≤1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. Various amplifying designs are shown, although the increased amplification decreases bandwidth. Bench tests show that the amplifier can withstand significant common mode DC voltage and measure 10 ns, and 50 mV signals.

  3. Shock

    MedlinePlus

    ... problems) Hypovolemic shock (caused by too little blood volume) Anaphylactic shock (caused by allergic reaction) Septic shock ( ... as heart attack or heart failure ) Low blood volume (as with heavy bleeding or dehydration ) Changes in ...

  4. Shock

    MedlinePlus

    ... Emergencies A-Z Share this! Home » Emergency 101 Shock Shock is a serious, often life-threatening medical condition ... of death for critically ill or injured people. Shock results when the body is not getting enough ...

  5. Energy trapping and shock disintegration in a composite granular medium.

    PubMed

    Daraio, C; Nesterenko, V F; Herbold, E B; Jin, S

    2006-02-10

    We report the first experimental observation of impulse confinement and the disintegration of shock and solitary waves in one-dimensional strongly nonlinear composite granular materials. The chains consist of alternating ensembles of beads with high and low elastic moduli (more than 2 orders of magnitude difference) of different masses. The trapped energy is contained within the "softer" sections of the composite chain and is slowly released in the form of weak, separated pulses over an extended period of time. This effect is enhanced by using a specific group assembly and precompression. PMID:16486993

  6. Motion of the Heliospheric Termination Shock at High Heliographic Latitude

    NASA Technical Reports Server (NTRS)

    Barnes, Aaron

    1995-01-01

    We expect the mean distance of the heliospheric termination shock to be greater (smaller) at polar latitudes than at equatorial latitudes, depending on whether the mean dynamic pressure of the solar wind is greater or smaller at high latitudes. The heliospheric termination shock is expected to move in response to variation in upstream solar wind conditions, so that at any particular instant the termination shock will resemble a distorted asymmetric balloon with some parts moving inward and others moving outward. If the shock is a gasdynamic or magnetohydrodynamic shock the results of the analysis depend only very weakly on the nature of the upstream disturbance; typical speeds of the disturbed shock are approximately 100 to 200 km/s. In the absence of a significant latitude gradient of the typical magnitude of solar wind disturbances typical motions of the disturbed shock at polar latitudes would be about twice as fast, due to the higher speed of the high-latitude wind. If the dynamics of the termination shock are dominated by acceleration of the anomalous component of the cosmic rays, the motion of the shock in response to a given disturbance is substantially slower than in the gasdynamic case. Conceivably, particle acceleration might be a less important effect at higher latitudes, and we envision the possibility of a termination shock that is dominated by particle acceleration at lower latitudes and is an MHD shock at high latitudes. In this event high latitude solar wind disturbances would produce substantially larger inward and outward motions of the shock in the polar regions.

  7. Compression of High Porosity Aluminum by Strong Shock Waves

    SciTech Connect

    Vildanov, V. G.; Gorshkov, M. M.; Slobodenjukov, V. M.; Borshchevsky, A. O.; Petrovtsev, A. V.

    2006-08-03

    Measuring results on shock compression of porous aluminum with initial density of {rho}00 = 0.6 g/cm3 up to pressures of 170 GPa are presented under shock wave velocity measurement scale of 40 mm. High underground explosion was used as a shock wave source. Obtained results were described in shock wave velocity (D) -- particle velocity (u) coordinates by linear dependence of D = 0.647 + 1.26 u at 4.6 {<=} u {<=} 14.8 km/s.

  8. Theoretical study of the effect of the size of a high-energy proton beam of the Large Hadron Collider on the formation and propagation of shock waves in copper irradiated by 450-GeV proton beams

    NASA Astrophysics Data System (ADS)

    Ryazanov, A. I.; Stepakov, A. V.; Vasilyev, Ya. S.; Ferrari, A.

    2014-02-01

    The interaction of 450-GeV protons with copper, which is the material of the collimators of the Large Hadron Collider, has been theoretically studied. A theoretical model for the formation and propagation of shock waves has been proposed on the basis of the analysis of the energy released by a proton beam in the electronic subsystem of the material owing to the deceleration of secondary particles appearing in nuclear reactions induced by this beam on the electronic subsystem of the material. The subsequent transfer of the energy from the excited electronic subsystem to the crystal lattice through the electron-phonon interaction has been described within the thermal spike model [I.M. Lifshitz, M.I. Kaganov, and L.V. Tanatarov, Sov. Phys. JETP 4, 173 (1957); I.M. Lifshitz, M.I. Kaganov, and L.V. Tanatarov, At. Energ. 6, 391 (1959); K. Yasui, Nucl. Instrum. Methods Phys. Res., Sect. B 90, 409 (1994)]. The model of the formation of shock waves involves energy exchange processes between excited electronic and ionic subsystems of the irradiated material and is based on the hydrodynamic approximation proposed by Zel'dovich [Ya.B. Zel'dovich and Yu.P. Raizer, Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena (Nauka, Moscow, 1966; Dover, New York, 2002)]. This model makes it possible to obtain the space-time distributions of the main physical characteristics (temperatures of the ionic and electronic subsystems, density, pressure, etc.) in materials irradiated by high-energy proton beams and to analyze the formation and propagation of shock waves in them. The nonlinear differential equations describing the conservation laws of mass, energy, and momentum of electrons and ions in the Euler variables in the case of the propagation of shock waves has been solved with the Godunov scheme [S. K. Godunov, A.V. Zabrodin, M.Ya. Ivanov, A.N. Kraiko, and G.P. Prokopov, Numerical Solution of Multidimensional Problems in Gas Dynamics (Nauka, Moscow, 1976) [in Russian

  9. Performance of Low Dissipative High Order Shock-Capturing Schemes for Shock-Turbulence Interactions

    NASA Technical Reports Server (NTRS)

    Sandham, N. D.; Yee, H. C.

    1998-01-01

    Accurate and efficient direct numerical simulation of turbulence in the presence of shock waves represents a significant challenge for numerical methods. The objective of this paper is to evaluate the performance of high order compact and non-compact central spatial differencing employing total variation diminishing (TVD) shock-capturing dissipations as characteristic based filters for two model problems combining shock wave and shear layer phenomena. A vortex pairing model evaluates the ability of the schemes to cope with shear layer instability and eddy shock waves, while a shock wave impingement on a spatially-evolving mixing layer model studies the accuracy of computation of vortices passing through a sequence of shock and expansion waves. A drastic increase in accuracy is observed if a suitable artificial compression formulation is applied to the TVD dissipations. With this modification to the filter step the fourth-order non-compact scheme shows improved results in comparison to second-order methods, while retaining the good shock resolution of the basic TVD scheme. For this characteristic based filter approach, however, the benefits of compact schemes or schemes with higher than fourth order are not sufficient to justify the higher complexity near the boundary and/or the additional computational cost.

  10. Nonadiabatic electron heating at high-Mach-number perpendicular shocks

    NASA Technical Reports Server (NTRS)

    Tokar, R. L.; Aldrich, C. H.; Forslund, D. W.; Quest, K. B.

    1986-01-01

    Fully kinetic simulations of high-Mach-number (HMN) perpendicular collisionless shocks are described. It is shown that electron acceleration in the cross-shock electron field can produce downstream electron temperature significantly higher than those expected for adiabatic compression. The momentum space for test electrons at Mach 6 is illustrated.

  11. Design, Simulation and Fabrication of Triaxial MEMS High Shock Accelerometer.

    PubMed

    Zhang, Zhenhai; Shi, Zhiguo; Yang, Zhan; Xie, Zhihong; Zhang, Donghong; Cai, De; Li, Kejie; Shen, Yajing

    2015-04-01

    On the basis of analyzing the disadvantage of other structural accelerometer, three-axis high g MEMS piezoresistive accelerometer was put forward in order to apply to the high-shock test field. The accelerometer's structure and working principle were discussed in details. The simulation results show that three-axis high shock MEMS accelerometer can bear high shock. After bearing high shock impact in high-shock shooting test, three-axis high shock MEMS accelerometer can obtain the intact metrical information of the penetration process and still guarantee the accurate precision of measurement in high shock load range, so we can not only analyze the law of stress wave spreading and the penetration rule of the penetration process of the body of the missile, but also furnish the testing technology of the burst point controlling. The accelerometer has far-ranging application in recording the typical data that projectile penetrating hard target and furnish both technology guarantees for penetration rule and defend engineering. PMID:26353519

  12. The Maximum Energy of Accelerated Particles in Relativistic Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Sironi, Lorenzo; Spitkovsky, Anatoly; Arons, Jonathan

    2013-07-01

    The afterglow emission from gamma-ray bursts (GRBs) is usually interpreted as synchrotron radiation from electrons accelerated at the GRB external shock that propagates with relativistic velocities into the magnetized interstellar medium. By means of multi-dimensional particle-in-cell simulations, we investigate the acceleration performance of weakly magnetized relativistic shocks, in the magnetization range 0 <~ σ <~ 10-1. The pre-shock magnetic field is orthogonal to the flow, as generically expected for relativistic shocks. We find that relativistic perpendicular shocks propagating in electron-positron plasmas are efficient particle accelerators if the magnetization is σ <~ 10-3. For electron-ion plasmas, the transition to efficient acceleration occurs for σ <~ 3 × 10-5. Here, the acceleration process proceeds similarly for the two species, since the electrons enter the shock nearly in equipartition with the ions, as a result of strong pre-heating in the self-generated upstream turbulence. In both electron-positron and electron-ion shocks, we find that the maximum energy of the accelerated particles scales in time as ɛmaxvpropt 1/2. This scaling is shallower than the so-called (and commonly assumed) Bohm limit ɛmaxvpropt, and it naturally results from the small-scale nature of the Weibel turbulence generated in the shock layer. In magnetized plasmas, the energy of the accelerated particles increases until it reaches a saturation value ɛsat/γ0 mic 2 ~ σ-1/4, where γ0 mic 2 is the mean energy per particle in the upstream bulk flow. Further energization is prevented by the fact that the self-generated turbulence is confined within a finite region of thickness vpropσ-1/2 around the shock. Our results can provide physically grounded inputs for models of non-thermal emission from a variety of astrophysical sources, with particular relevance to GRB afterglows.

  13. Alternate methods for high level pyrotechnic shock simulation

    NASA Astrophysics Data System (ADS)

    Gray, Phillip J., Sr.

    Two effective methods to recreate a realistic pyrotechnic shock are presented. The first method employs a resonant beam and is used for SRS levels of 12,000 G or more. The test unit is at one end of the beam and a hammer strikes the opposite end causing a shock to be transmitted to the other end of the fixture. The second method is based on a standard shaker system with a resonant beam to amplify the input signal. The engineer defines the duration of the shock signal induced to the vibration amplifier using the GenRad 2514 controller. The shock signal is then input via the shaker to the resonant beam, which amplifies the signal to produce the desired response at the end of the fixture. The shock response spectrum stays within a +/-6 dB tolerance with levels as high as 3000 G peak. These methods are repeatable, reliable, cost-effective, and consistent with a real pyroevent.

  14. Shock characterization of an ultra-high strength concrete

    NASA Astrophysics Data System (ADS)

    Erzar, B.; Pontiroli, C.; Buzaud, E.

    2016-05-01

    Nowadays, the design of protective structures may imply ultra-high performance concretes. These materials present a compressive strength 5 times higher than standard concretes. However, few reliable data on the shock response of such materials are available in the literature. Thus, a characterization of an ultra-high strength concrete has been conducted by means of hydrostatic and triaxial tests in the quasi-static regime, and plate impact experiments for shock response. Data have been gathered up to 6 GPa and a simple modelling approach has been applied to get a reliable representation of the shock compression of this concrete.

  15. Generation of high pressure shocks relevant to the shock-ignition intensity regime

    SciTech Connect

    Batani, D.; Folpini, G.; Giuffrida, L.; Maheut, Y.; Malka, G.; Nicolai, Ph.; Ribeyre, X.; Antonelli, L.; Atzeni, S.; Marocchino, A.; Schiavi, A.; Badziak, J.; Chodukowski, T.; Kalinowska, Z.; Pisarczyk, T.; Rosinski, M.; Baffigi, F.; Cristoforetti, G.; Gizzi, L. A.; Koester, P.; and others

    2014-03-15

    An experiment was performed using the PALS laser to study laser-target coupling and laser-plasma interaction in an intensity regime ≤10{sup 16} W/cm{sup 2}, relevant for the “shock ignition” approach to Inertial Confinement Fusion. A first beam at low intensity was used to create an extended preformed plasma, and a second one to create a strong shock. Pressures up to 90 Megabars were inferred. Our results show the importance of the details of energy transport in the overdense region.

  16. Enhanced ion beam energy by relativistic transparency in laser-driven shock ion acceleration

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kuk; Hur, Min Sup

    2015-11-01

    We investigated the effects of relativistic transparency (RT) on electrostatic shock ion acceleration. Penetrating portion of the laser pulse directly heats up the electrons to a very high temperature in backside of the target, resulting in a condition of high shock velocity. The reflected portion of the pulse can yield a fast hole boring and density compression in near-critical density plasma to satisfy the electrostatic shock condition; 1.5 high speed electrostatic shock reflects upstream ions up to velocity ~2vsh. In 1D PIC simulation, we have clearly observed RT-based shock acceleration which generates significantly higher ion beam energy in comparison to that in a purely opaque plasma. In multi-dimensional systems, various instabilities should be considered such as Weibel-like instability, which causes filamentation during the laser penetration. From series of comparisons of linearly polarized and circularly polarized pulses for the RT-based shock, we observed the circularly polarized pulse is usually more advantageous in reducing the instability, possibly leading to better RT-based shock acceleration. The Basic Science Research Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT and Future Planning (Grant number NRF- 2013R1A1A2006353).

  17. Intensity and energy spectrum of electrons accelerated in the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.

    1974-01-01

    Shock waves accelerate charged particles in the solar atmosphere, in interplanetary space and around the earth's magnetosphere. Acceleration of both electrons and protons occurs in the earth's bow-shock. The acceleration of protons up to 100 keV appears to be a steady state process and may even occur upstream from the bow shock due to waves generated by reflected solar wind protons. The electrons, on the other hand, are known to be accelerated in or near the shock. The intensity of these electrons ranges from about 100 to 2,000 per sr-sq cm-sec-keV at 14 keV. The energy spectrum is not a simple power low and is highly variable. If segments of the spectra are fitted to a power low, slopes ranging from -2 to -4.5 result over the energy range 0.5 to 100 keV.

  18. On high-resolution finite volume shock capturing schemes

    NASA Astrophysics Data System (ADS)

    Causon, D. M.; Clarke, N.

    1990-07-01

    Conservative, shock capturing methods for the unsteady Euler equations are reviewed and it is shown that the concepts of entropy satisfaction and total variation diminution can be applied to well-known classical schemes. For an associated scheme to be efficient in applications, it is necessary that it be constructed with economy of implementation in mind, and that it be able to capture strong shock waves with high resolution. We describe a scheme which is efficient in both respects.

  19. On high resolution finite volume shock capturing schemes

    NASA Astrophysics Data System (ADS)

    Causon, D. M.; Clarke, N.

    Conservative shock-capturing methods for the unsteady Euler equations are reviewed, and it is shown that the concepts of entropy satisfaction and total variation diminution can be applied to well known classical schemes. For an associated scheme to be efficient in applications, it is necessary that it be constructed with economy of implementation in mind, and that it be able to capture strong shock waves with high resolution. A scheme which is efficient in both respects is described.

  20. Shock-induced synthesis of high temperature superconducting materials

    DOEpatents

    Ginley, D.S.; Graham, R.A.; Morosin, B.; Venturini, E.L.

    1987-06-18

    It has now been determined that the unique features of the high pressure shock method, especially the shock-induced chemical synthesis technique, are fully applicable to high temperature superconducting materials. Extraordinarily high yields are achievable in accordance with this invention, e.g., generally in the range from about 20% to about 99%, often in the range from about 50% to about 90%, lower and higher yields, of course, also being possible. The method of this invention involves the application of a controlled high pressure shock compression pulse which can be produced in any conventional manner, e.g., by detonation of a high explosive material, the impact of a high speed projectile or the effect of intense pulsed radiation sources such as lasers or electron beams. Examples and a discussion are presented.

  1. Structures and properties of materials recovered from high shock pressures

    SciTech Connect

    Nellis, W.J.

    1994-03-01

    Shock compression produces high dynamic pressures, densities, temperatures, and their quench rates. Because of these extreme conditions, shock compression produces materials with novel crystal structures, microstructures, and physical properties. Using a 6.5-m-long two-stage gun, we perform experiments with specimens up to 10 mm in diameter and 0.001--1 mm thick. For example, oriented disks of melt-textured superconducting YBa{sub 2}Cu{sub 3}O{sub 7} were shocked to 7 GPa without macroscopic fracture. Lattice defects are deposited in the crystal, which improve magnetic hysteresis at {approximately}1 kOe. A computer code has been developed to simulate shock compaction of 100 powder particles. Computations will be compared with experiments with 15--20 {mu}m Cu powders. The method is applicable to other powders and dynamic conditions.

  2. Very high Mach number shocks - Theory. [in space plasmas

    NASA Technical Reports Server (NTRS)

    Quest, Kevin B.

    1986-01-01

    The theory and simulation of collisionless perpendicular supercritical shock structure is reviewed, with major emphasis on recent research results. The primary tool of investigation is the hybrid simulation method, in which the Newtonian orbits of a large number of ion macroparticles are followed numerically, and in which the electrons are treated as a charge neutralizing fluid. The principal results include the following: (1) electron resistivity is not required to explain the observed quasi-stationarity of the earth's bow shock, (2) the structure of the perpendicular shock at very high Mach numbers depends sensitively on the upstream value of beta (the ratio of the thermal to magnetic pressure) and electron resistivity, (3) two-dimensional turbulence will become increasingly important as the Mach number is increased, and (4) nonadiabatic bulk electron heating will result when a thermal electron cannot complete a gyrorbit while transiting the shock.

  3. PVDF shock sensors: applications to polar materials and high explosives.

    PubMed

    Bauer, F

    2000-01-01

    Ferroelectric polymers (PVDF) with well-defined and precisely known electrical properties are now routinely available from commercial sources. Electrical processing with the Bauer cyclic poling method can produce individual films with well-defined remanent polarization up to 9 /spl mu/C/cm/sup 2/. These polymers provide an unusual opportunity to study the structure and physical properties of materials subjected to shock loading. The behavior of PVDF has been studied over a wide range of pressures using high-pressure shock loading and has yielded well-behaved, reproducible data up to 25 GPa in inert materials. The application of PVDF gauges for recording shock waves induced in polar materials such as Kel-F, PMMA, or in reactive materials is hampered by observations of anomalous responses due to shock-induced polarization or an electrical charge released inside a shock-compressed explosive. A solution using an appropriate electrical shielding has been identified and applied to PVDF for shock measurement studies of Kel-F, and for Hugoniot measurements of high explosives (PH). Furthermore, shock pressure profiles obtained with in situ PVDF gauges in porous HE (Formex) in a detonation regime have been achieved. Typical results of shock pressure profile versus time show a fast superpressure of a few nanoseconds followed by a pressure release down to a plateau level and then by a pressure decay. More accurate measurements are reported with electrically improved PVDF gauges as well as with 0.25 mm/sup 2/ active area PVDF gauges. PMID:18238691

  4. Shock ignition of thermonuclear fuel with high areal density.

    PubMed

    Betti, R; Zhou, C D; Anderson, K S; Perkins, L J; Theobald, W; Solodov, A A

    2007-04-13

    A novel method by C. Zhou and R. Betti [Bull. Am. Phys. Soc. 50, 140 (2005)] to assemble and ignite thermonuclear fuel is presented. Massive cryogenic shells are first imploded by direct laser light with a low implosion velocity and on a low adiabat leading to fuel assemblies with large areal densities. The assembled fuel is ignited from a central hot spot heated by the collision of a spherically convergent ignitor shock and the return shock. The resulting fuel assembly features a hot-spot pressure greater than the surrounding dense fuel pressure. Such a nonisobaric assembly requires a lower energy threshold for ignition than the conventional isobaric one. The ignitor shock can be launched by a spike in the laser power or by particle beams. The thermonuclear gain can be significantly larger than in conventional isobaric ignition for equal driver energy. PMID:17501359

  5. Elastic precursor shock waves in tantalum at very high strain rates

    NASA Astrophysics Data System (ADS)

    Crowhurst, Jonathan; Armstrong, Michael; Gates, Sean; Radousky, Harry; Zaug, Joseph

    2015-06-01

    We have obtained data from micron-thick tantalum films using our ultrafast laser shock platform. By measuring free surface velocity time histories at breakout, and shock wave arrival times at different film thicknesses, we have been able to estimate the dependence of particle and shock velocities on propagation distances and strain rates. We will show how elastic precursor shock waves depend on strain rate in the regime up to and above 109 s-1. We find that while elastic amplitudes are very large at very early times decay occurs rapidly as propagation distance increases. Finally we will consider the prospects for using these data to obtain the dynamic strength of tantalum at these very high strain rates. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 with Laboratory directed Research and Development funding (12ERD042).

  6. Elastic precursor shock waves in tantalum at very high strain rates

    NASA Astrophysics Data System (ADS)

    Crowhurst, Jonathan; Armstrong, Michael; Radousky, Harry; Zaug, Joseph; Gates, Sean

    2015-03-01

    We have obtained data from micron-thick tantalum films using our ultrafast laser shock platform. By measuring free surface velocity time histories at breakout, and shock wave arrival times at different film thicknesses, we have been able to estimate the dependence of particle and shock velocities on propagation distances and strain rates. We will show how elastic precursor shock waves depend on strain rate in the regime up to and above 109 s-1. We find that while elastic amplitudes are very large at very early times decay occurs rapidly as propagation distance increases. Finally we will consider the prospects for using these data to obtain the dynamic strength of tantalum at these very high strain rates. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 with Laboratory directed Research and Development funding (12ERD042).

  7. Electron acceleration in a nonrelativistic shock with very high Alfvén Mach number.

    PubMed

    Matsumoto, Y; Amano, T; Hoshino, M

    2013-11-22

    Electron acceleration associated with various plasma kinetic instabilities in a nonrelativistic shock with very high Alfvén Mach number (M(A)~45) is revealed by means of a two-dimensional fully kinetic particle-in-cell simulation. Electromagnetic (ion Weibel) and electrostatic (ion-acoustic and Buneman) instabilities are strongly activated at the same time in different regions of the two-dimensional shock structure. Relativistic electrons are quickly produced predominantly by the shock surfing mechanism with the Buneman instability at the leading edge of the foot. The energy spectrum has a high-energy tail exceeding the upstream ion kinetic energy accompanying the main thermal population. This gives a favorable condition for the ion-acoustic instability at the shock front, which in turn results in additional energization. The large-amplitude ion Weibel instability generates current sheets in the foot, implying another dissipation mechanism via magnetic reconnection in a three-dimensional shock structure in the very-high-M(A) regime. PMID:24313495

  8. Periodic Architecture for High Performance Shock Absorbing Composites

    PubMed Central

    Misra, Abha; Kumar, Praveen

    2013-01-01

    A novel composite architecture consisting of a periodic arrangement of closely-spaced spheres of a stiff material embedded in a soft matrix is proposed for extremely high damping and shock absorption capacity. Efficacy of this architecture is demonstrated by compression loading a composite, where multiple steel balls were stacked upon each other in a polydimethylsiloxane (PDMS) matrix, at a low strain-rate of 0.05 s−1 and a very high strain-rate of >2400 s−1. The balls slide over each other upon loading, and revert to their original position when the load is removed. Because of imposition of additional strains into the matrix via this reversible, constrained movement of the balls, the composite absorbs significantly larger energy and endures much lesser permanent damage than the monolithic PDMS during both quasi-static and impact loadings. During the impact loading, energy absorbed per unit weight for the composite was ~8 times larger than the monolithic PDMS. PMID:23792699

  9. Quantified Energy Dissipation Rates in the Terrestrial Bow Shock. 1.; Analysis Techniques and Methodology

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Sibeck, D. G.; Breneman, A.W.; Le Contel, O.; Cully, C.; Turner, D. L.; Angelopoulos, V.; Malaspina, D. M.

    2014-01-01

    We present a detailed outline and discussion of the analysis techniques used to compare the relevance of different energy dissipation mechanisms at collisionless shock waves. We show that the low-frequency, quasi-static fields contribute less to ohmic energy dissipation, (-j · E ) (minus current density times measured electric field), than their high-frequency counterparts. In fact, we found that high-frequency, large-amplitude (greater than 100 millivolts per meter and/or greater than 1 nanotesla) waves are ubiquitous in the transition region of collisionless shocks. We quantitatively show that their fields, through wave-particle interactions, cause enough energy dissipation to regulate the global structure of collisionless shocks. The purpose of this paper, part one of two, is to outline and describe in detail the background, analysis techniques, and theoretical motivation for our new results presented in the companion paper. The companion paper presents the results of our quantitative energy dissipation rate estimates and discusses the implications. Together, the two manuscripts present the first study quantifying the contribution that high-frequency waves provide, through wave-particle interactions, to the total energy dissipation budget of collisionless shock waves.

  10. Vacuum high-harmonic generation and electromagnetic shock

    NASA Astrophysics Data System (ADS)

    Böhl, P.; King, B.; Ruhl, H.

    2016-04-01

    > When one takes into account the presence of virtual charged states in the quantum vacuum, a nonlinear self-interaction can arise in the propagation of electromagnetic fields. This self-interaction is often referred to as `real photon-photon scattering'. When the centre-of-mass energy of colliding photons is much lower than the rest energy of an electron-positron pair, this quantum effect can be included in the classical field equations of motion as a vacuum current and charge density using the Heisenberg-Euler Lagrangian. Using analytical and numerical methods for subcritical fields, the intrinsic solution to Maxwell's equations has been found for counterpropagating probe and pump plane waves in the presence of vacuum four- and six-wave mixing. In the corresponding all-order solution for the scattered probe, a route to vacuum high-harmonic generation is identified in which a long phase length can compensate for the weakness of interacting fields. The resulting shocks in the probe carrier wave and envelope are studied for different parameter regimes and polarisation set-ups. In this special issue, we study two additional set-ups: that of a slowly varying single-cycle background to highlight the effect of an oscillating background on the probe harmonic spectrum, and that of a few-cycle probe to highlight the smoothing of the harmonic peaks produced by a wider spectrum of probe photons. We also correct sign errors in an earlier publication.

  11. Stability of shocks relating to the shock ignition inertial fusion energy scheme

    SciTech Connect

    Davie, C. J. Bush, I. A.; Evans, R. G.

    2014-08-15

    Motivated by the shock ignition approach to improve the performance of inertial fusion targets, we make a series of studies of the stability of shock waves in planar and converging geometries. We examine stability of shocks moving through distorted material and driving shocks with non-uniform pressure profiles. We then apply a fully 3D perturbation, following this spherically converging shock through collapse to a distorted plane, bounce and reflection into an outgoing perturbed, broadly spherical shock wave. We find broad shock stability even under quite extreme perturbation.

  12. High doses of corticosteroids in the treatment of septic shock.

    PubMed

    Hellman, A; Alestig, K

    1985-01-01

    High doses of corticosteroids are reported to be beneficial in the treatment of septic shock in many animal species, e.g. dog, rat and rabbit. Recent findings in baboons subjected to E. coli shock indicate that early treatment with a combination of antibiotics and steroids strongly enhance survival rate. In clinical studies the protective effects of steroids are more ambiguous, however. In part this may be explained by variations in the amount of steroids used or by the fact that in some studies the steroid is administered late in shock. The dose recommended, 30 mg/kg bw of methylprednisolone or an equivalent amount of another glucocorticoid given once or twice, is based on animal as well as clinical documentation. PMID:3911703

  13. Therapeutic Strategies for High-Dose Vasopressor-Dependent Shock

    PubMed Central

    Bassi, Estevão; Park, Marcelo; Azevedo, Luciano Cesar Pontes

    2013-01-01

    There is no consensual definition of refractory shock. The use of more than 0.5 mcg/kg/min of norepinephrine or epinephrine to maintain target blood pressure is often used in clinical trials as a threshold. Nearly 6% of critically ill patients will develop refractory shock, which accounts for 18% of deaths in intensive care unit. Mortality rates are usually greater than 50%. The assessment of fluid responsiveness and cardiac function can help to guide therapy, and inotropes may be used if hypoperfusion signs persist after initial resuscitation. Arginine vasopressin is frequently used in refractory shock, although definite evidence to support this practice is still missing. Its associations with corticosteroids improved outcome in observational studies and are therefore promising alternatives. Other rescue therapies such as terlipressin, methylene blue, and high-volume isovolemic hemofiltration await more evidence before use in routine practice. PMID:24151551

  14. An artificial energy method for calculating flows with shocks

    NASA Technical Reports Server (NTRS)

    Rose, M. E.

    1980-01-01

    The artificial-viscosity method, first proposed by von Neumann and Richtmyer, introduces an artificial viscous pressure term in regions of compression such that an increase in entropy occurs in shock transition zones. The paper describes how dissipative flows can be induced by reducing the total energy available for adiabatic processes in shock zones. A class of inviscid fluid flows, called semiflows, is described in which the flows exhibit thermodynamic differences. Induced dissipative flows modify the pressure in regions of compression in a manner analogous to the artificial-viscosity method and for a gas, the effect is equivalent to suitably modifying the gas constant in the equation of state. By employing MacCormack's method and the usual non-adiabatic equations, numerical solutions of a Riemann problem are compared with the modified artificial energy method, showing that the dissipation effect predicted by the analytical formulation is reflected in the numerical method as well.

  15. High-speed spectrograph for shock tube studies

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.

    1973-01-01

    Instrument provides information on spatial distribution of electron density of gas flow in high-performance shock tube. System permits measurement of profiles of hydrogen-alpha and -beta lines with enough spectral range to record spectral features from the near ultraviolet to the long-wavelength cutoff of photographic film.

  16. Shock.

    PubMed

    Wacker, David A; Winters, Michael E

    2014-11-01

    Critically ill patients with undifferentiated shock are complex and challenging cases in the ED. A systematic approach to assessment and management is essential to prevent unnecessary morbidity and mortality. The simplified, systematic approach described in this article focuses on determining the presence of problems with cardiac function (the pump), intravascular volume (the tank), or systemic vascular resistance (the pipes). With this approach, the emergency physician can detect life-threatening conditions and implement time-sensitive therapy. PMID:25441032

  17. Material response mechanisms are needed to obtain highly accurate experimental shock wave data

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry

    2015-06-01

    The field of shock wave compression of matter has provided a simple set of equations relating thermodynamic and kinematic parameters that describe the conservation of mass, momentum and energy across a steady shock wave with one-dimensional flow. Well-known condensed matter shock wave experimental results will be reviewed to see whether the assumptions required for deriving these simple R-H equations are met. Note that the material compression model is not required for deriving the 1-D conservation flow equations across a steady shock front. However, this statement is misleading from a practical experimental viewpoint since obtaining small systematic errors in shock wave measured parameters requires the material compression and release mechanisms to be known. A brief review will be presented on systematic errors in shock wave data from common experimental techniques for fluids, elastic-plastic solids, materials with negative volume phase transitions, glass and ceramic materials, and high explosives. Issues related to time scales of experiments and quasi-steady flow will also be presented.

  18. High-pressure phases in shock-induced melt of the unique highly shocked LL6 chondrite Northwest Africa 757

    NASA Astrophysics Data System (ADS)

    Hu, Jinping; Sharp, Thomas G.

    2016-07-01

    Northwest Africa 757 is unique in the LL chondrite group because of its abundant shock-induced melt and high-pressure minerals. Olivine fragments entrained in the melt transform partially and completely into ringwoodite. Plagioclase and Ca-phosphate transform to maskelynite, lingunite, and tuite. Two distinct shock-melt crystallization assemblages were studied by FIB-TEM analysis. The first melt assemblage, which includes majoritic garnet, ringwoodite plus magnetite-magnesiowüstite, crystallized at pressures of 20-25 GPa. The other melt assemblage, which consists of clinopyroxene and wadsleyite, solidified at ~15 GPa, suggesting a second veining event under lower pressure conditions. These shock features are similar to those in S6 L chondrites and indicate that NWA 757 experienced an intense impact event, comparable to the impact event that disrupted the L chondrite parent body at 470 Ma.

  19. High-pressure phases in shock-induced melt of the unique highly shocked LL6 chondrite Northwest Africa 757

    NASA Astrophysics Data System (ADS)

    Hu, Jinping; Sharp, Thomas G.

    2016-06-01

    Northwest Africa 757 is unique in the LL chondrite group because of its abundant shock-induced melt and high-pressure minerals. Olivine fragments entrained in the melt transform partially and completely into ringwoodite. Plagioclase and Ca-phosphate transform to maskelynite, lingunite, and tuite. Two distinct shock-melt crystallization assemblages were studied by FIB-TEM analysis. The first melt assemblage, which includes majoritic garnet, ringwoodite plus magnetite-magnesiowüstite, crystallized at pressures of 20-25 GPa. The other melt assemblage, which consists of clinopyroxene and wadsleyite, solidified at ~15 GPa, suggesting a second veining event under lower pressure conditions. These shock features are similar to those in S6 L chondrites and indicate that NWA 757 experienced an intense impact event, comparable to the impact event that disrupted the L chondrite parent body at 470 Ma.

  20. Measuring high pressure equation of state of polystyrene using laser driven shock wave

    NASA Astrophysics Data System (ADS)

    Shu, Hua; Huang, Xiuguang; Ye, Junjian; Wu, Jiang; Jia, Guo; Fang, Zhiheng; Xie, Zhiyong; Zhou, Huazhen; Fu, Sizu

    2015-11-01

    High precision polystyrene equation of state data were measured using laser-driven shock waves with pressures from 180 GPa to 700 GPa. α quartz was used as standard material, the shock wave trajectory in quartz and polystyrene was measured using the Velocity Interferometer for Any Reflector (VISAR). Instantaneous shock velocity in quartz and polystyrene was obtained when the shock wave pass the interface. This provided ~1% precision in shock velocity measurements.

  1. [Research on Energy Distribution During Osteoarthritis Treatment Using Shock Wave Lithotripsy].

    PubMed

    Zhang, Shinian; Wang, Xiaofeng; Zhang, Dong

    2015-04-01

    Extracorporeal shock wave treatment is capable of providing a non-surgical and effective treatment modality for patients suffering from osteoarthritis. The major objective of current works is to investigate how the shock wave (SW) field would change if a bony structure exists in the path of the acoustic wave. Firstly, a model of finite element method (FEM) was developed based on Comsol software in the present study. Then, high-speed photography experiments were performed to record cavitation bubbles with the presence of mimic bone. On the basis of comparing experimental with simulated results, the effectiveness of FEM model could be verified. Finally, the energy distribution during extracorporeal shock wave treatment was predicted. The results showed that the shock wave field was deflected with the presence of bony structure and varying deflection angles could be observed as the bone shifted up in the z-direction relative to shock wave geometric focus. Combining MRI/CT scans to FEM modeling is helpful for better standardizing the treatment dosage and optimizing treatment protocols in the clinic. PMID:26211244

  2. Development of a shock noise prediction code for high-speed helicopters - The subsonically moving shock

    NASA Technical Reports Server (NTRS)

    Tadghighi, H.; Holz, R.; Farassat, F.; Lee, Yung-Jang

    1991-01-01

    A previously defined airfoil subsonic shock-noise prediction formula whose result depends on a mapping of the time-dependent shock surface to a time-independent computational domain is presently coded and incorporated in the NASA-Langley rotor-noise prediction code, WOPWOP. The structure and algorithms used in the shock-noise prediction code are presented; special care has been taken to reduce computation time while maintaining accuracy. Numerical examples of shock-noise prediction are presented for hover and forward flight. It is confirmed that shock noise is an important component of the quadrupole source.

  3. Optical observation of shock waves and cavitation bubbles in high intensity laser-induced shock processes

    SciTech Connect

    Marti-Lopez, L.; Ocana, R.; Porro, J. A.; Morales, M.; Ocana, J. L.

    2009-07-01

    We report an experimental study of the temporal and spatial dynamics of shock waves, cavitation bubbles, and sound waves generated in water during laser shock processing by single Nd:YAG laser pulses of nanosecond duration. A fast ICCD camera (2 ns gate time) was employed to record false schlieren photographs, schlieren photographs, and Mach-Zehnder interferograms of the zone surrounding the laser spot site on the target, an aluminum alloy sample. We recorded hemispherical shock fronts, cylindrical shock fronts, plane shock fronts, cavitation bubbles, and phase disturbance tracks.

  4. High strength and high ductility behavior of 6061-T6 alloy after laser shock processing

    NASA Astrophysics Data System (ADS)

    Gencalp Irizalp, Simge; Saklakoglu, Nursen

    2016-02-01

    The plastic deformation behavior of 6061-T6 alloy which was subjected to severe plastic deformation (SPD) at high strain rates during laser shock processing (LSP) was researched. In LSP-treated materials, the near surface microstructural change was examined by TEM and fracture surfaces after tensile testing were examined by SEM. An increase in strength of metallic materials brings about the decrease in ductility. In this study, the results showed that LSP-treated 6061-T6 alloy exhibited both high strength and high ductility. TEM observation showed that stacking fault (SF) ribbon enlarged, deformation twins formed and twin boundary increased in LSP-treated 6061-T6 alloy. This observation was an indication of stacking fault energy (SFE) decrease. Work hardening capability was recovered after LSP impacts.

  5. Low-energy proton increases associated with interplanetary shock waves.

    NASA Technical Reports Server (NTRS)

    Palmeira, R. A. R.; Allum, F. R.; Rao, U. R.

    1971-01-01

    Impulsive increases in the low energy proton flux observed by the Explorer 34 satellite, in very close time association with geomagnetic storm sudden commencements are described. It is shown that these events are of short duration (20-30 min) and occur only during the decay phase of a solar cosmic-ray flare event. The differential energy spectrum and the angular distribution of the direction of arrival of the particles are discussed. Two similar increases observed far away from the earth by the Pioneer 7 and 8 deep-space probes are also presented. These impulsive increases are compared with Energetic Storm Particle events and their similarities and differences are discussed. A model is suggested to explain these increases, based on the sweeping and trapping of low energy cosmic rays of solar origin by the advancing shock front responsible for the sudden commencement detected on the earth.

  6. Energy harvesting from human motion: exploiting swing and shock excitations

    NASA Astrophysics Data System (ADS)

    Ylli, K.; Hoffmann, D.; Willmann, A.; Becker, P.; Folkmer, B.; Manoli, Y.

    2015-02-01

    Modern compact and low power sensors and systems are leading towards increasingly integrated wearable systems. One key bottleneck of this technology is the power supply. The use of energy harvesting techniques offers a way of supplying sensor systems without the need for batteries and maintenance. In this work we present the development and characterization of two inductive energy harvesters which exploit different characteristics of the human gait. A multi-coil topology harvester is presented which uses the swing motion of the foot. The second device is a shock-type harvester which is excited into resonance upon heel strike. Both devices were modeled and designed with the key constraint of device height in mind, in order to facilitate the integration into the shoe sole. The devices were characterized under different motion speeds and with two test subjects on a treadmill. An average power output of up to 0.84 mW is achieved with the swing harvester. With a total device volume including the housing of 21 cm3 a power density of 40 μW cm-3 results. The shock harvester generates an average power output of up to 4.13 mW. The power density amounts to 86 μW cm-3 for the total device volume of 48 cm3. Difficulties and potential improvements are discussed briefly.

  7. Collisionless shock generation in high-speed counterstreaming plasma flows by a high-power laser

    SciTech Connect

    Morita, T.; Aoki, H.; Sakawa, Y.; Kuramitsu, Y.; Kato, T. N.; Dono, S.; Tanji, H.; Li, Y. T.; Zhang, Y.; Liu, X.; Zhong, J. Y.; Takabe, H.; Zhang, J.

    2010-12-15

    The experimental demonstration of the formation of a strong electrostatic (ES) collisionless shock has been carried out with high-speed counterstreaming plasmas, produced by a high-power laser irradiation, without external magnetic field. The nearly four times density jump observed in the experiment shows a high Mach-number shock. This large density jump is attributed to the compression of the downstream plasma by momentum transfer by ion reflection of the upstream plasma. Particle-in-cell (PIC) simulation shows the production of a collisionless high Mach-number ES shock with counterstreaming interaction of two plasma slabs with different temperatures and densities, as pointed out by Sorasio et al. [Phys. Rev. Lett. 96, 045005 (2006)]. It is speculated that the shock discontinuity is balanced with the momentum of incoming and reflected ions and the predominant pressure of the electrons in the downstream with PIC simulation.

  8. Energy-Dependent Ionization States of Shock-Accelerated Particles in the Solar Corona

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.; Ng, C. K.; Tylka, A. J.

    2000-01-01

    We examine the range of possible energy dependence of the ionization states of ions that are shock-accelerated from the ambient plasma of the solar corona. If acceleration begins in a region of moderate density, sufficiently low in the corona, ions above about 0.1 MeV/amu approach an equilibrium charge state that depends primarily upon their speed and only weakly on the plasma temperature. We suggest that the large variations of the charge states with energy for ions such as Si and Fe observed in the 1997 November 6 event are consistent with stripping in moderately dense coronal. plasma during shock acceleration. In the large solar-particle events studied previously, acceleration occurs sufficiently high in the corona that even Fe ions up to 600 MeV/amu are not stripped of electrons.

  9. Quantified Energy Dissipation Rates in the Terrestrial Bow Shock. 2; Waves and Dissipation

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Sibeck, D. G.; Breneman, A. W.; Le Contel, O.; Cully, C.; Turner, D. L.; Angelopoulos, V.; Malaspina, D. M.

    2014-01-01

    We present the first quantified measure of the energy dissipation rates, due to wave-particle interactions, in the transition region of the Earth's collision-less bow shock using data from the Time History of Events and Macro-Scale Interactions during Sub-Storms spacecraft. Our results show that wave-particle interactions can regulate the global structure and dominate the energy dissipation of collision-less shocks. In every bow shock crossing examined, we observed both low-frequency (less than 10 hertz) and high-frequency (approximately or greater than10 hertz) electromagnetic waves throughout the entire transition region and into the magnetosheath. The low-frequency waves were consistent with magnetosonic-whistler waves. The high-frequency waves were combinations of ion-acoustic waves, electron cyclotron drift instability driven waves, electrostatic solitary waves, and whistler mode waves. The high-frequency waves had the following: (1) peak amplitudes exceeding delta B approximately equal to 10 nanoteslas and delta E approximately equal to 300 millivolts per meter, though more typical values were delta B approximately equal to 0.1-1.0 nanoteslas and delta E approximately equal to 10-50 millivolts per meter (2) Poynting fluxes in excess of 2000 microWm(sup -2) (micro-waves per square meter) (typical values were approximately 1-10 microWm(sup -2) (micro-waves per square meter); (3) resistivities greater than 9000 omega meters; and (4) associated energy dissipation rates greater than 10 microWm(sup -3) (micro-waves per cubic meter). The dissipation rates due to wave-particle interactions exceeded rates necessary to explain the increase in entropy across the shock ramps for approximately 90 percent of the wave burst durations. For approximately 22 percent of these times, the wave-particle interactions needed to only be less than or equal to 0.1 percent efficient to balance the nonlinear wave steepening that produced the shock waves. These results show that wave

  10. 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.

  11. 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

  12. Electron heating in a Monte Carlo model of a high Mach number, supercritical, collisionless shock

    NASA Technical Reports Server (NTRS)

    Ellison, Donald C.; Jones, Frank C.

    1987-01-01

    Preliminary work in the investigation of electron injection and acceleration at parallel shocks is presented. A simple model of electron heating that is derived from a unified shock model which includes the effects of an electrostatic potential jump is described. The unified shock model provides a kinetic description of the injection and acceleration of ions and a fluid description of electron heating at high Mach number, supercritical, and parallel shocks.

  13. Low-energy ion acceleration at quasi-perpendicular shocks: Transverse diffusion

    NASA Technical Reports Server (NTRS)

    Giacalone, J.; Jokipii, J. R.

    1995-01-01

    The problem of ion injection and acceleration at quasi perpendicular shocks has been the subject of some debate over the past two decades. It is widely known that these shocks efficiently accelerate particles that are well in the high-energy tail of the distribution. However, the issue of injection, or the acceleration of low-energy ions, has yet to reach a consensus. The fundamental issue is whether there is enough diffusion normal to the magnetic field for the particles to remain near the shock. Since transverse diffusion is a physical process that is not well understood in space plasmas, this is an important, and difficult issue to address. In this report, we will investigate the ion injection problem by performing test particle orbit integrations using synthesized turbulent fields. These fields are fully three-dimensional so that transverse diffusion is possible (cross-field diffusion is not possible in geometries where the electromagnetic fields are less than three dimensional). The synthesized fields are produced by superimposing a three-dimensional wave field on a background field. For completeness, we will compare the results from this model with the more well-established theories, such as the diffusive approximation and scatter-free shock drift acceleration. We will also compare these results with other numerical simulation techniques such as the well known hybrid simulation, and other test-particle calculations in which the shock fields are specified to have less than three dimensions. We will also discuss some recent relevant observations and how these compare with our results.

  14. Shock initiation studies on high concentration hydrogen peroxide

    SciTech Connect

    Sheffield, Stephen A; Dattelbaum, Dana M; Stahl, David B; Gibson, L. Lee; Bartram, Brian D.

    2009-01-01

    Concentrated hydrogen peroxide (H{sub 2}O{sub 2}) has been known to detonate for many years. However, because of its reactivity and the difficulty in handling and confining it, along with the large critical diameter, few studies providing basic information about the initiation and detonation properties have been published. We are conducting a study to understand and quantify the initiation and detonation properties of highly concentrated H{sub 2}O{sub 2} using a gas-driven two-stage gun to produce well defined shock inputs. Multiple magnetic gauges are used to make in-situ measurements of the growth of reaction and subsequent detonation in the liquid. These experiments are designed to be one-dimensional to eliminate any difficulties that might be encountered with large critical diameters. Because of the concern of the reactivity of the H{sub 2}O{sub 2} with the confining materials, a remote loading system has been developed. The gun is pressurized, then the cell is filled and the experiment shot within less than three minutes. TV cameras are attached to the target so the cell filling can be monitored. Several experiments have been completed on {approx}98 wt % H{sub 2}O{sub 2}/H{sub 2}O mixtures; initiation has been observed in some experiments that shows homogeneous shock initiation behavior. The initial shock pressurizes and heats the mixture. After an induction time, a thermal explosion type reaction produces an evolving reactive wave that strengthens and eventually overdrives the first wave producing a detonation. From these measurements, we have determined unreacted Hugoniot information, times (distances) to detonation (Pop-plot points) that indicate low sensitivity, and detonation velocities of high concentration H{sub 2}O{sub 2}/H{sub 2}O solutions that agree with earlier estimates.

  15. The Energy Spectrum of Energetic Particles Downstream of Turbulent Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Giacalone, Joe; Neugebauer, Marcia

    2008-01-01

    Using simple analytic considerations, numerical simulations, and data analysis, we discuss the physics of charged-particle acceleration by turbulent, rippled, collisionless shocks. The standard theory of diffusive shock acceleration predicts that the energetic-particle energy spectrum, in the region of shocked plasma, is a function of the plasma density jump. But because of the interaction of the shock with plasma turbulence, the jump in plasma density varies in time and from place to place on the shock front. Here we show that for reasonable parameters, the shape of the energetic-particle energy spectra downstream of any given shock is nearly independent of location along the shock front, even though the density jump varies. This is because energetic particles are mobile and sample many turbulent fluctuations during their acceleration. This result holds for shocks having smaller scale ripples than the large-scale radius of curvature (Dc) of the shock. Thus, it applies to the interpretation of spacecraft observations of traveling interplanetary shocks provided the spacecraft separation is less than Dc. This result is confirmed with simple analytic considerations and numerical simulations that solve the combined magnetohydrodynamic equations for a plasma and energetic test particles using the well-known Parker transport equation. This conclusion is further supported by our analysis of ACE and Geotail observations of a few interplanetary shocks.

  16. High-speed helicopter rotor noise - Shock waves as a potent source of sound

    NASA Technical Reports Server (NTRS)

    Farassat, F.; Lee, Yung-Jang; Tadghighi, H.; Holz, R.

    1991-01-01

    In this paper we discuss the problem of high speed rotor noise prediction. In particular, we propose that from the point of view of the acoustic analogy, shocks around rotating blades are sources of sound. We show that, although for a wing at uniform steady rectilinear motion with shocks the volume quadrupole and shock sources cancel in the far field to the order of 1/r, this cannot happen for rotating blades. In this case, some cancellation between volume quadrupoles and shock sources occurs, yet the remaining shock noise contribution is still potent. A formula for shock noise prediction is presented based on mapping the deformable shock surface to a time independent region. The resulting equation is similar to Formulation 1A of Langley. Shock noise prediction for a hovering model rotor for which experimental noise data exist is presented. The comparison of measured and predicted acoustic data shows good agreement.

  17. On the Fielding of a High Gain, Shock-Ignited Target on the National Ignitiion Facility in the Near Term

    SciTech Connect

    Perkins, L J; Betti, R; Schurtz, G P; Craxton, R S; Dunne, A M; LaFortune, K N; Schmitt, A J; McKenty, P W; Bailey, D S; Lambert, M A; Ribeyre, X; Theobald, W R; Strozzi, D J; Harding, D R; Casner, A; Atzemi, S; Erbert, G V; Andersen, K S; Murakami, M; Comley, A J; Cook, R C; Stephens, R B

    2010-04-12

    Shock ignition, a new concept for igniting thermonuclear fuel, offers the possibility for a near-term ({approx}3-4 years) test of high gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy and without the need for new laser hardware. In shock ignition, compressed fusion fuel is separately ignited by a strong spherically converging shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, fusion energy gains of {approx}60 may be achievable on NIF at laser drive energies around {approx}0.5MJ. Because of the simple all-DT target design, its in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early time LPI preheat, and use of present (indirect drive) laser hardware, this target may be easier to field on NIF than a conventional (polar) direct drive hotspot ignition target. Like fast ignition, shock ignition has the potential for high fusion yields at low drive energy, but requires only a single laser with less demanding timing and spatial focusing requirements. Of course, conventional symmetry and stability constraints still apply. In this paper we present initial target performance simulations, delineate the critical issues and describe the immediate-term R&D program that must be performed in order to test the potential of a high gain shock ignition target on NIF in the near term.

  18. High thermal shock resistance of the hot rolled and swaged bulk W-ZrC alloys

    NASA Astrophysics Data System (ADS)

    Xie, Z. M.; Liu, R.; Miao, S.; Yang, X. D.; Zhang, T.; Fang, Q. F.; Wang, X. P.; Liu, C. S.; Lian, Y. Y.; Liu, X.; Luo, G. N.

    2016-02-01

    The thermal shock (single shot) resistance and mechanical properties of the W-0.5wt% ZrC (WZC) alloys manufactured by ordinary sintering followed by swaging or rolling process were investigated. No cracks or surface melting were detected on the surface of the rolled WZC alloy plates after thermal shock at a power density of 0.66 GW/m2 for 5 ms, while primary intergranular cracks appear on the surface of the swaged WZC samples after thermal shock at a power density of 0.44 GW/m2 for 5 ms. Three point bending tests indicate that the rolled WZC alloy has a flexural strength of ˜2.4 GPa and a total strain of 1.8% at room temperature, which are 100% and 260% higher than those of the swaged WZC, respectively. The fracture energy density of the rolled WZC alloy is 3.23 × 107 J/m3, about 10 times higher than that of the swaged WZC (2.9 × 106 J/m3). The high thermal shock resistance of the rolled WZC alloys can be ascribed to their extraordinary ductility and plasticity.

  19. The Guitar nebula - A bow shock from a slow-spin, high-velocity neutron star

    NASA Technical Reports Server (NTRS)

    Cordes, James M.; Romani, Roger W.; Lundgren, Scott C.

    1993-01-01

    The discovery is reported of a prominent nebula produced by the motion of a high-velocity pulsar, PSR 2224 + 65, through partially neutral gas. The pulsar's transverse speed of over about 800 km/s makes it arguably the fastest known star in the Galaxy and guarantees that it will ultimately escape the Galactic potential well. A deep H-alpha image reveals a bright head and a giant limb-brightened 'body' whose variable width suggests that the ambient interstellar gas has density variations on length scales less than 0.1 pc. Thermalization of shock energy occurs at a rate of about 0.01 times the pulsar's spindown loss rate. These observations provide some insights into the likelihood of finding shocks around other pulsars and the use of nebulae to find high-velocity neutron stars either not acting as pulsars or with their radiation beamed away from the earth.

  20. Unsteady shock wave diagnostics with high-speed imaging

    NASA Astrophysics Data System (ADS)

    Skews, B. W.; Kleine, H.; MacLucas, D.; Takehara, K.; Teranishi, H.; Etoh, T. G.

    2008-11-01

    The visual study of unsteady shock wave dynamics has in the past predominantly been done using single-shot images. The advent of ultra-fast, good-resolution high-speed digital cameras has changed this state of affairs and allows the true development of the flow to be studied. It enables the detection of weaker features which are easily overlooked in singleshot visualizations by virtue of the fact that human vision is very sensitive to detecting the motion of an object, even if it generates only a faint optical signal. Recent application of these devices to the study of the focusing of a shock wave in a cylindrical cavity has identified a number of previously unknown features, while other features that previously had been inadequately reported could be clearly identified and explained The observation of deliberately generated weak disturbances allows the quantification of which part of the flow is influenced by which part of the boundaries encompassing it. Whilst the imaging itself is very useful it is also highly desirable to use techniques from which quantitative data can be obtained. Color, such as in direction- and magnitude-indicating color schlieren, and polychrome shearing interferometry, adds an additional dimension to such investigations.

  1. Pyrotechnic shock response predictions combining statistical energy analysis and local random phase reconstruction.

    PubMed

    Bodin, E; Brévart, B; Wagstaff, P; Borello, G

    2002-07-01

    Numerous pyrotechnic devices are used on satellites to separate structural subsystems, deploy appendages, and activate on-board operating subsystems. The firing of these pyrotechnic mechanisms leads to severe impulsive loads which could sometimes lead to failures in electronic systems. The objective of the present investigation is to assess the relevance of a method combining deterministic calculations and statistical energy analysis to predict the time overall shock environment of electronic equipment components. The methods are applied to the low- and high-frequency ranges, respectively, which may be defined using a modal parameter based on the effective transmissibility. Initially, in order to address the problem of the low-frequency content of the mechanical shock pulse, the linear dynamic response of the equipment was calculated using direct time integration of a finite element model of the structure. The inputs in the form of the accelerations measured in all three directions at each of the four bolted interfaces were injected into the model. The high-frequency content of the shock response is taken into account by considering the intrinsic dynamic filtering of the equipment. This frequency filter magnitude is extrapolated from the transfer function given by statistical energy analysis between the different imposed accelerations and the response accelerations. Their associated phases are synthesized by considering pseudo-modal phase variations around the group velocity of the structural flexural waves. Combining the effects of the high-frequency filter outputs and the low-frequency finite element calculations yields good predictions of the equipment shock time response over the whole frequency range of interest. PMID:12141340

  2. Pyrotechnic shock response predictions combining statistical energy analysis and local random phase reconstruction

    NASA Astrophysics Data System (ADS)

    Bodin, E.; Brevart, B.; Wagstaff, P.; Borello, G.

    2002-07-01

    Numerous pyrotechnic devices are used on satellites to separate structural subsystems, deploy appendages, and activate on-board operating subsystems. The firing of these pyrotechnic mechanisms leads to severe impulsive loads which could sometimes lead to failures in electronic systems. The objective of the present investigation is to assess the relevance of a method combining deterministic calculations and statistical energy analysis to predict the time overall shock environment of electronic equipment components. The methods are applied to the low- and high-frequency ranges, respectively, which may be defined using a modal parameter based on the effective transmissibility. Initially, in order to address the problem of the low-frequency content of the mechanical shock pulse, the linear dynamic response of the equipment was calculated using direct time integration of a finite element model of the structure. The inputs in the form of the accelerations measured in all three directions at each of the four bolted interfaces were injected into the model. The high-frequency content of the shock response is taken into account by considering the intrinsic dynamic filtering of the equipment. This frequency filter magnitude is extrapolated from the transfer function given by statistical energy analysis between the different imposed accelerations and the response accelerations. Their associated phases are synthesized by considering pseudo-modal phase variations around the group velocity of the structural flexural waves. Combining the effects of the high-frequency filter outputs and the low-frequency finite element calculations yields good predictions of the equipment shock time response over the whole frequency range of interest. copyright 2002 Acoustical Society of America.

  3. Shock ignition: a new approach to high gain inertial confinement fusion on the national ignition facility.

    PubMed

    Perkins, L J; Betti, R; LaFortune, K N; Williams, W H

    2009-07-24

    Shock ignition, an alternative concept for igniting thermonuclear fuel, is explored as a new approach to high gain, inertial confinement fusion targets for the National Ignition Facility (NIF). Results indicate thermonuclear yields of approximately 120-250 MJ may be possible with laser drive energies of 1-1.6 MJ, while gains of approximately 50 may still be achievable at only approximately 0.2 MJ drive energy. The scaling of NIF energy gain with laser energy is found to be G approximately 126E (MJ);{0.510}. This offers the potential for high-gain targets that may lead to smaller, more economic fusion power reactors and a cheaper fusion energy development path. PMID:19659364

  4. Characteristics of a piezoresistive accelerometer in high frequency, high shock environments

    SciTech Connect

    Bateman, V.I.; Davie, N.T.; Brown, F.A.

    1993-12-31

    The characteristics of a piezoresistive accelerometer in shock environments are being studied at Sandia National Laboratories in the Mechanical Shock Testing Laboratory. A Hopkinson bar capability has been developed to extend our understanding of the piezoresistive accelerometer with and without mechanical isolation in the high frequency, high shock environments where measurements are being made. Two different Hopkinson bar materials are being used: titanium and beryllium. The characteristics of the piezoresistive accelerometer for frequencies of DC-10 kHz and shock magnitudes of up to 4,000 g as determined from measurements with a titanium Hopkinson bar are presented. The SNL uniaxial shock isolation technique has demonstrated acceptable characteristics for a temperature range of {minus}50{degree}F to +186{degree}F and a frequency bandwidth of DC to 10 kHz. These characteristics have been verified by the calibration of the Hopkinson bar used for accelerometer testing. The beryllium Hopkinson bar configuration is described. Preliminary characteristics of the piezoresistive accelerometer at a nominal shock level of 17,000 g for a frequency range of DC-50 kHz are presented.

  5. High-efficiency shock-wave generator for extracorporeal lithotripsy.

    PubMed

    Broyer, P; Cathignol, D; Theillère, Y; Mestas, J L

    1996-09-01

    In extracorporeal lithotripsy, the electro-acoustic efficiency of electrohydraulic generators is limited by the inductance of the electrical discharge circuit. A new shock-wave generator is described that uses a coaxial discharge line enabling electro-acoustic efficiency to be greatly increased. The line is built using a para-electric ceramic with a relative dielectric constant of 1700, manufactured for use in high-voltage impulse mode. A coaxial spark gap, with minimal inductance, has been developed to obtain the triggered breakdown of the discharge line. Shock waves are created with a coaxial electrode plugged directly into the spark gap and immersed in an electrolyte of degassed saline. Electrode gap and electrolyte resistivity are adjusted to match the resistivity of the electrolyte volume between the underwater electrodes to the characteristic impedance of the line. The discharge line generates in the medium a rectangular current pulse with an amplitude of about 6000 A and a rise time of 50 ns. Compared with conventional generators, measurements of the expansive peak pressure pulse show an increase of 105% at 10 kV, 86.5% at 12 kV and 34.5% at 14 kV charging voltage. Electro-acoustic efficiency is found to be 11% instead of 5.5% for a conventional discharge circuit. PMID:8945854

  6. Sensitivity of once-shocked, weathered high explosives

    SciTech Connect

    Williams, K.L.; Harris, B.W.

    1998-07-01

    Effects caused by stimulating once-shocked, weathered high explosives (OSW-HE) are investigated. The sensitivity of OSW-HE to mechanical stimuli was determined using standard industry tests. Some initial results are given. Pieces of OSW-HE were collected from active and inactive firing sites and from an area surrounding a drop tower at Los Alamos where skid and spigot tests were done. Samples evaluated were cast explosives or plastic bonded explosive (PBX) formulations containing cyclotrimethylenetrinitramine (RDX), cyclotetramethylene tetranitramine (HMX), 2,4,6-trinitrotoluene (TNT), mock or inert HE [tris(beta-chloroethyl)phosphate (CEF)], barium nitrate, cyanuric acid, talc, and Kel-F. Once-shocked, weathered LX-10 Livermore explosive [HMX/Viton A, (95/5 wt %)], PBX 9011 [HMX/Estane, (90/10 wt %)], PBX 9404 [HMX/nitrocellulose, tris(beta-chloroethyl) phosphate, (94/3/3 wt %)], Composition B or cyclotol (TNT/RDX explosives), and PBX 9007 (90% RDX, 9.1% styrene, 0.5% dioctyl phthalate, and 0.45 resin) were subjected to the hammer test, the drop-weight impact sensitivity test, differential thermal analysis (DTA), the spark test, the Henkin`s critical temperature test, and the flame test. Samples were subjected to remote, wet cutting and drilling; remote, liquid-nitrogen-cooled grinding and crushing; and scanning electron microscope (SEM) surface analyses for morphological changes.

  7. Simulations of high Mach number perpendicular shocks with resistive electrons

    NASA Technical Reports Server (NTRS)

    Quest, K. B.

    1986-01-01

    A simulation code which models the ions as microparticles and the electrons as a resistive massless fluid is employed to study the structure of high Mach number perpendicular shocks. It is found that stable stationary shock solutions can be obtained for Alfven Mach numbers (M sub A) between 5 and 60 for upstream plasmas where the ratio of the plasma pressure to the magnetic pressure is 1, providing that the upstream resistive diffusion length is much smaller than the ion inertial length. For much larger resistive diffusion lengths, the magnetic field overshoot is damped, and the imbalance in the electron momentum equation results in a periodic fluctuation of the fraction of reflected ions. In the limit of M sub A of less than 10, the magnetic overshoot and the fraction of reflected ions increase with increasing M sub A, while at higher Mach numbers the fraction of reflected ions peaks at about 40 percent and the magnetic field overshoot increases at a much slower rate. Electron inertial effects are also considered.

  8. Shock response of the commercial high explosive Detasheet

    NASA Astrophysics Data System (ADS)

    Asay, B. W.; Ramsay, J. B.; Anderson, M. U.; Graham, R. A.

    1994-12-01

    The mechanical and chemical response of the flexible commercial high explosive DetasheetR is studied under controlled impact and plane-wave, high explosive loading. Results on nonreactive material behavior, sound speed, shock-initiation sensitivity and detonation pressure are presented. The material is found to respond in a viscous manner reminiscent of viscoelastic response of polymeric materials. Time-resolved pressure and pressure-rate measurements with PVDF piezoelectric polymer gauges are presented along with Manganin pressure and plate-dent test measurements of detonation pressure. Detonation pressures of 18GPa are indicated. Pressure measurements show initiation of reaction between 3 and 8 mm for an impact stress of 3.1 GPa. Plane wave loading wedge tests show run distances to detonation consistent with the pressure measurements, and with behavior like that of XTX8003 (80 % PETN/20 % Sylgard 182R).

  9. The effect of stochastic re-acceleration on the energy spectrum of shock-accelerated protons

    SciTech Connect

    Afanasiev, Alexandr; Vainio, Rami; Kocharov, Leon

    2014-07-20

    The energy spectra of particles in gradual solar energetic particle (SEP) events do not always have a power-law form attributed to the diffusive shock acceleration mechanism. In particular, the observed spectra in major SEP events can take the form of a broken (double) power law. In this paper, we study the effect of a process that can modify the power-law spectral form produced by the diffusive shock acceleration: the stochastic re-acceleration of energetic protons by enhanced Alfvénic turbulence in the downstream region of a shock wave. There are arguments suggesting that this process can be important when the shock propagates in the corona. We consider a coronal magnetic loop traversed by a shock and perform Monte Carlo simulations of interactions of shock-accelerated protons with Alfvén waves in the loop. The wave-particle interactions are treated self-consistently, so the finiteness of the available turbulent energy is taken into account. The initial energy spectrum of particles is taken to be a power law. The simulations reveal that the stochastic re-acceleration leads either to the formation of a spectrum that is described in a wide energy range by a power law (although the resulting power-law index is different from the initial one) or to a broken power-law spectrum. The resulting spectral form is determined by the ratio of the energy density of shock-accelerated protons to the wave energy density in the shock's downstream region.

  10. Electron Energy Distributions at Relativistic Shock Sites: Observational Constraints from the Cygnus A Hotspots

    SciTech Connect

    Cheung, C.C.Teddy; Stawarz, L.; Harris, D.E.; Ostrowski, M.

    2007-10-15

    We report new detections of the hotspots in Cygnus A at 4.5 and 8.0 microns with the Spitzer Space Telescope. Together with detailed published radio observations and synchrotron self-Compton modeling of previous X-ray detections, we reconstruct the underlying electron energy spectra of the two brightest hotspots (A and D). The low-energy portion of the electron distributions have flat power-law slopes (s {approx} 1.5) up to the break energy which corresponds almost exactly to the mass ratio between protons and electrons; we argue that these features are most likely intrinsic rather than due to absorption effects. Beyond the break, the electron spectra continue to higher energies with very steep slopes s>3. Thus, there is no evidence for the 'canonical' s=2 slope expected in 1st order Fermi-type shocks within the whole observable electron energy range. We discuss the significance of these observations and the insight offered into high-energy particle acceleration processes in mildly relativistic shocks.

  11. IPShocks: Database of Interplanetary Shock Waves

    NASA Astrophysics Data System (ADS)

    Isavnin, Alexey; Lumme, Erkka; Kilpua, Emilia; Lotti, Mikko; Andreeova, Katerina; Koskinen, Hannu; Nikbakhsh, Shabnam

    2016-04-01

    Fast collisionless shocks are one of the key interplanetary structures, which have also paramount role for solar-terrestrial physics. In particular, coronal mass ejection driven shocks accelerate particles to high energies and turbulent post-shock flows may drive intense geomagnetic storms. We present comprehensive Heliospheric Shock Database (ipshocks.fi) developed and hosted at University of Helsinki. The database contains currently over 2000 fast forward and fast reverse shocks observed by Wind, ACE, STEREO, Helios, Ulysses and Cluster spacecraft. In addition, the database has search and sort tools based on the spacecraft, time range, and several key shock parameters (e.g., shock type, shock strength, shock angle), data plots for each shock and data download options. These features allow easy access to shocks and quick statistical analyses. All current shocks are identified visually and analysed using the same procedure.

  12. Solution of the hydrodynamic device model using high-order non-oscillatory shock capturing algorithms

    NASA Technical Reports Server (NTRS)

    Fatemi, Emad; Jerome, Joseph; Osher, Stanley

    1989-01-01

    A micron n+ - n - n+ silicon diode is simulated via the hydrodynamic model for carrier transport. The numerical algorithms employed are for the non-steady case, and a limiting process is used to reach steady state. The simulation employs shock capturing algorithms, and indeed shocks, or very rapid transition regimes, are observed in the transient case for the coupled system, consisting of the potential equation and the conservation equations describing charge, momentum, and energy transfer for the electron carriers. These algorithms, termed essentially non-oscillatory, were successfully applied in other contexts to model the flow in gas dynamics, magnetohydrodynamics, and other physical situations involving the conservation laws in fluid mechanics. The method here is first order in time, but the use of small time steps allows for good accuracy. Runge-Kutta methods allow one to achieve higher accuracy in time if desired. The spatial accuracy is of high order in regions of smoothness.

  13. High-pressure shock behavior of WC and Ta2O5 powders.

    SciTech Connect

    Knudson, Marcus D.; Reinhart, William Dodd; Vogler, Tracy John; Root, Seth

    2011-10-01

    Planar shock experiments were conducted on granular tungsten carbide (WC) and tantalum oxide (Ta{sub 2}O{sub 5}) using the Z machine and a 2-stage gas gun. Additional shock experiments were also conducted on a nearly fully dense form of Ta{sub 2}O{sub 5}. The experiments on WC yield some of the highest pressure results for granular materials obtained to date. Because of the high distention of Ta{sub 2}O{sub 5}, the pressures obtained were significantly lower, but the very high temperatures generated led to large contributions of thermal energy to the material response. These experiments demonstrate that the Z machine can be used to obtain accurate shock data on granular materials. The data on Ta{sub 2}O{sub 5} were utilized in making improvements to the P-{lambda} model for high pressures; the model is found to capture the results not only of the Z and gas gun experiments but also those from laser experiments on low density aerogels. The results are also used to illustrate an approach for generating an equation of state using only the limited data coming from nanoindentation. Although the EOS generated in this manner is rather simplistic, for this material it gives reasonably good results.

  14. Low-energy particle acceleration and compression at the termination shock and in the heliosheath

    SciTech Connect

    Florinski, V.; Le Roux, J. A.; Decker, R. B.

    2008-08-25

    We discuss some theoretical aspects of pickup ion acceleration at the solar wind termination shock and beyond in the heliosheath. Our model of anisotropic transport permits a wide range of acceleration mechanisms, including (a) adiabatic compression by the shock of PUI suprathermal tails, (b) standard diffusive acceleration at the shock, (c) mirroring by the magnetic field kink at a quasi-perpendicular shock, and (d) momentum diffusion in the solar wind and the heliosheath. It is shown that momentum diffusion in the heliosheath is an efficient particle accelerator at low energies. We also investigate the processing of a pre-accelerated pickup ion spectra by the termination shock and analyze the long-term averaged anisotropies of the combined distributions near a shock whose obliquity varies with time.

  15. The chemical shock tube as a tool for studying high-temperature chemical kinetics

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.

    1986-01-01

    Although the combustion of hydrocarbons is our primary source of energy today, the chemical reactions, or pathway, by which even the simplest hydro-carbon reacts with atmospheric oxygen to form CO2 and water may not always be known. Furthermore, even when the reaction pathway is known, the reaction rates are always under discussion. The shock tube has been an important and unique tool for building a data base of reaction rates important in the combustion of hydrocarbon fuels. The ability of a shock wave to bring the gas sample to reaction conditions rapidly and homogeneously makes shock-tube studies of reaction kinetics extremely attractive. In addition to the control and uniformity of reaction conditions achieved with shock-wave methods, shock compression can produce gas temperatures far in excess of those in conventional reactors. Argon can be heated to well over 10 000 K, and temperatures around 5000 K are easily obtained with conventional shock-tube techniques. Experiments have proven the validity of shock-wave theory; thus, reaction temperatures and pressures can be calculated from a measurement of the incident shock velocity. A description is given of the chemical shock tube and auxiliary equipment and of two examples of kinetic experiments conducted in a shock tube.

  16. Motion of the heliospheric termination shock. 2: Energy loss due to energetic particle acceleration

    NASA Astrophysics Data System (ADS)

    Barnes, Aaron

    1994-04-01

    We present a generalization of earlier analysis of the motion of the heliospheric termination shock in response to heliospheric disturbances (Barnes, 1993) (paper 1), to allow jump conditions that include an energy sink at the shock front. The motivation for this study is that acceleration of the anomalous cosmic ray component may in fact represent such a sink. We have idealized the situation by assuming an infinitely thin shock parameterized by a quantity lambda(0 less than or equals lambda less than or equals 1), defined as the fraction of solar wind energy that is lost due to acceleration of the energetic particle component. If the sink is strong (consuming, say, 50% or more of the incident solar wind energy), the model leads to the following principal conclusions: (1) the shocked plasma would be much denser and cooler than in the standard gasdynamic case, thereby leading to more favorable conditions for direct observation of the shocked plasma; (2) the equilibrium shock position would be slightly farther (less than 10%) from the Sun than in the standard model; (3) as in the gasdynamic case, the shock would normally be in motion, so that the instantaneous position of the termination shock is not determined by interstellar conditions but by the recent history of the wind that has passed through the termination shock; and (4) the response of the shock to upstream disturbances would be similar to the response in the gasdynamic case, but the speed of the new termination shock would be somewhat smaller (probably by a f actor of 4 or less). We estimate that this speed is typically, approximately a few tens of kilometers per second corresponding to an inward or outward excursion of order of less than 1 to several AU, rather less than conventional estimates of several tens of AU.

  17. Motion of the heliospheric termination shock. 2: Energy loss due to energetic particle acceleration

    NASA Technical Reports Server (NTRS)

    Barnes, Aaron

    1994-01-01

    We present a generalization of earlier analysis of the motion of the heliospheric termination shock in response to heliospheric disturbances (Barnes, 1993) (paper 1), to allow jump conditions that include an energy sink at the shock front. The motivation for this study is that acceleration of the anomalous cosmic ray component may in fact represent such a sink. We have idealized the situation by assuming an infinitely thin shock parameterized by a quantity lambda(0 less than or equals lambda less than or equals 1), defined as the fraction of solar wind energy that is lost due to acceleration of the energetic particle component. If the sink is strong (consuming, say, 50% or more of the incident solar wind energy), the model leads to the following principal conclusions: (1) the shocked plasma would be much denser and cooler than in the standard gasdynamic case, thereby leading to more favorable conditions for direct observation of the shocked plasma; (2) the equilibrium shock position would be slightly farther (less than 10%) from the Sun than in the standard model; (3) as in the gasdynamic case, the shock would normally be in motion, so that the instantaneous position of the termination shock is not determined by interstellar conditions but by the recent history of the wind that has passed through the termination shock; and (4) the response of the shock to upstream disturbances would be similar to the response in the gasdynamic case, but the speed of the new termination shock would be somewhat smaller (probably by a f actor of 4 or less). We estimate that this speed is typically, approximately a few tens of kilometers per second corresponding to an inward or outward excursion of order of less than 1 to several AU, rather less than conventional estimates of several tens of AU.

  18. Acceleration of low-energy protons and alpha particles at interplanetary shock waves

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Hovestadt, D.; Ipavich, F. M.; Gloeckler, G.

    1983-01-01

    The low-energy protons and alpha particles in the energy range 30 keV/charge to 150 keV/charge associated with three different interplanetary shock waves in the immediate preshock and postshock region are studied using data obtained by the ISEE 3. The spatial distributions in the preshock and postshock medium are presented, and the dependence of the phase space density at different energies on the distance from the shock and on the form of the distribution function of both species immediately at the shock is examined. It is found that in the preshock region the particles are flowing in the solar wind frame of reference away from the shock and in the postshock medium the distribution is more or less isotropic in this frame of reference. The distribution function in the postshock region can be represented by a power law in energy which has the same spectral exponent for both protons and alpha particles. It is concluded that the first-order Fermi acceleration process can consistently explain the data, although the spectra of diffuse bow shock associated particles are different from the spectra of the interplanetary shock-associated particles in the immediate vicinity of the shock. In addition, the mean free path of the low energy ions in the preshock medium is found to be considerably smaller than the mean free path determined by the turbulence of the background interplanetary medium.

  19. THE MAGNETIZATION DEGREE OF THE OUTFLOW POWERING THE HIGHLY POLARIZED REVERSE-SHOCK EMISSION OF GRB 120308A

    SciTech Connect

    Zhang, Shuai; Jin, Zhi-Ping; Wei, Da-Ming E-mail: dmwei@pmo.ac.cn

    2015-01-01

    GRB 120308A, a long duration γ-ray burst (GRB) detected by Swift, was distinguished by a highly polarized early optical afterglow emission that strongly suggests an ordered magnetic field component in the emitting region. In this work, we model the optical and X-ray emission in the reverse and forward shock scenario and show that the strength of the magnetic field in the reverse-shock region is ∼10 times stronger than that in the forward shock region. Consequently, the outflow powering the highly polarized reverse-shock optical emission was mildly magnetized at a degree of σ ∼ a few percent. Considering the plausible magnetic energy dissipation in both the acceleration and prompt emission phases of the GRB outflow, the afterglow data of GRB 120308A provides us with compelling evidence that, at least for some GRBs, a nonignorable fraction of the energy was released in the form of Poynting flux, confirming the finding first made in the reverse-forward shock emission modeling of the optical afterglow of GRB 990123 by Fan et al. in 2002 and Zhang et al. in 2003.

  20. Simulation of transient flow in a shock tunnel and a high Mach number nozzle

    NASA Technical Reports Server (NTRS)

    Jacobs, P. A.

    1991-01-01

    A finite volume Navier-Stokes code was used to simulate the shock reflection and nozzle starting processes in an axisymmetric shock tube and a high Mach number nozzle. The simulated nozzle starting processes were found to match the classical quasi-1-D theory and some features of the experimental measurements. The shock reflection simulation illustrated a new mechanism for the driver gas contamination of the stagnated test gas.

  1. Simulations of high-Mach-number collisionless perpendicular shocks in astrophysical plasmas

    NASA Technical Reports Server (NTRS)

    Quest, K. B.

    1985-01-01

    A problem of critical importance to space physics and astrophysics is the existence and properties of high-Mach-number shocks. Preliminary results of a simulation of a perpendicular shock with Alfven Mach number 22 are reported. It is shown that for sufficiently small electron resistivity the dissipation for this shock is provided by a periodic rather than time-stationary reflection of ions. The problem of electron heating and the extension to higher Mach numbers are discussed.

  2. Computational Study of 3-D Hot-Spot Initiation in Shocked Insensitive High-Explosive

    NASA Astrophysics Data System (ADS)

    Najjar, F. M.; Howard, W. M.; Fried, L. E.

    2011-06-01

    High explosive shock sensitivity is controlled by a combination of mechanical response, thermal properties, and chemical properties. The interplay of these physical phenomena in realistic condensed energetic materials is currently lacking. A multiscale computational framework is developed investigating hot spot (void) ignition in a single crystal of an insensitive HE, TATB. Atomistic MD simulations are performed to provide the key chemical reactions and these reaction rates are used in 3-D multiphysics simulations. The multiphysics code, ALE3D, is linked to the chemistry software, Cheetah, and a three-way coupled approach is pursued including hydrodynamics, thermal and chemical analyses. A single spherical air bubble is embedded in the insensitive HE and its collapse due to shock initiation is evolved numerically in time; while the ignition processes due chemical reactions are studied. Our current predictions showcase several interesting features regarding hot spot dynamics including the formation of a ``secondary'' jet. Results obtained with hydro-thermo-chemical processes leading to ignition growth will be discussed for various pore sizes and different shock pressures. LLNL-ABS-471438. This work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  3. Shock reliability analysis and improvement of MEMS electret-based vibration energy harvesters

    NASA Astrophysics Data System (ADS)

    Renaud, M.; Fujita, T.; Goedbloed, M.; de Nooijer, C.; van Schaijk, R.

    2015-10-01

    Vibration energy harvesters can serve as a replacement solution to batteries for powering tire pressure monitoring systems (TPMS). Autonomous wireless TPMS powered by microelectromechanical system (MEMS) electret-based vibration energy harvester have been demonstrated. The mechanical reliability of the MEMS harvester still has to be assessed in order to bring the harvester to the requirements of the consumer market. It should survive the mechanical shocks occurring in the tire environment. A testing procedure to quantify the shock resilience of harvesters is described in this article. Our first generation of harvesters has a shock resilience of 400 g, which is far from being sufficient for the targeted application. In order to improve this aspect, the first important aspect is to understand the failure mechanism. Failure is found to occur in the form of fracture of the device’s springs. It results from impacts between the anchors of the springs when the harvester undergoes a shock. The shock resilience of the harvesters can be improved by redirecting these impacts to nonvital parts of the device. With this philosophy in mind, we design three types of shock absorbing structures and test their effect on the shock resilience of our MEMS harvesters. The solution leading to the best results consists of rigid silicon stoppers covered by a layer of Parylene. The shock resilience of the harvesters is brought above 2500 g. Results in the same range are also obtained with flexible silicon bumpers, which are simpler to manufacture.

  4. Perspectives on High-Energy-Density Physics

    NASA Astrophysics Data System (ADS)

    Drake, R. Paul

    2008-11-01

    Much of 21st century plasma physics will involve work to produce, understand, control, and exploit very non-traditional plasmas. High-energy density (HED) plasmas are often examples, variously involving strong Coulomb interactions and few particles per Debeye sphere, dominant radiation effects, strongly relativistic effects, or strongly quantum-mechanical behavior. Indeed, these and other modern plasma systems often fall outside the early standard theoretical definitions of ``plasma''. This presentation will focus on two types of HED plasmas that exhibit non-traditional behavior. Our first example will be the plasmas produced by extremely strong shock waves. Shock waves are present across the entire realm of plasma densities, often in space or astrophysical contexts. HED shock waves (at pressures > 1 Mbar) enable studies in many areas, from equations of state to hydrodynamics to radiation hydrodynamics. We will specifically consider strongly radiative shocks, in which the radiative energy fluxes are comparable to the mechanical energy fluxes that drive the shocks. Modern HED facilities can produce such shocks, which are also present in dense, energetic, astrophysical systems such as supernovae. These shocks are also excellent targets for advanced simulations due to their range of spatial scales and complex radiation transport. Our second example will be relativistic plasmas. In general, these vary from plasmas containing relativistic particle beams, produced for some decades in the laboratory, to the relativistic thermal plasmas present for example in pulsar winds. Laboratory HED relativistic plasmas to date have been those produced by laser beams of irradiance ˜ 10^18 to 10^22 W/cm^2 or by accelerator-produced HED electron beams. These have applications ranging from generation of intense x-rays to production of proton beams for radiation therapy to acceleration of electrons. Here we will focus on electron acceleration, a spectacular recent success and a rare

  5. Probing magnetohydrodynamic shocks with high-J CO observations: W28F

    NASA Astrophysics Data System (ADS)

    Gusdorf, A.; Anderl, S.; Güsten, R.; Stutzki, J.; Hübers, H.-W.; Hartogh, P.; Heyminck, S.; Okada, Y.

    2012-06-01

    Context. Observing supernova remnants (SNRs) and modelling the shocks they are associated with is the best way to quantify the energy SNRs re-distribute back into the interstellar medium (ISM). Aims: We present comparisons of shock models with CO observations in the F knot of the W28 supernova remnant. These comparisons constitute a valuable tool to constrain both the shock characteristics and pre-shock conditions. Methods: New CO observations from the shocked regions with the APEX and SOFIA telescopes are presented and combined. The integrated intensities are compared to the outputs of a grid of models, which were combined from an MHD shock code that calculates the dynamical and chemical structure of these regions and a radiative transfer module based on the large velocity gradient (LVG) approximation. Results: We base our modelling method on the higher J CO transitions, which unambiguously trace the passage of a shock wave. We provide fits for the blue- and red-lobe components of the observed shocks. We find that only stationary, C-type shock models can reproduce the observed levels of CO emission. Our best models are found for a pre-shock density of 104 cm-3, with the magnetic field strength varying between 45 and 100 μG, and a slightly higher shock velocity for the so-called blue-shock (~25 km s-1) than for the red one (~20 km s-1). Our models also satisfactorily account for the pure rotational H2 emission that is observed with Spitzer. Appendices are available in electronic form at http://www.aanda.org

  6. High-frequency electrostatic waves near earth's bow shock

    NASA Technical Reports Server (NTRS)

    Onsager, T. G.; Holzworth, R. H.; Koons, H. C.; Bauer, O. H.; Gurnett, D. A.

    1989-01-01

    Electrostatic wave measurements from the Active Magnetospheric Particle Tracer Explorer Ion Release Module have been used to investigate the wave modes and their possible generation mechanisms in the earth's bow shock and magnetosheath. It is demonstrated that electrostatic waves are present in the bow shock and magnetosheath with frequencies above the maximum frequency for Doppler-shifted ion acoustic waves, yet below the plasma frequency. Waves in this frequency range are tentatively identified as electron beam mode waves. Data from 45 bow shock crossings are then used to investigate possible correlations between the electrostatic wave properties and the near-shock plasma parameters. The most significant relationships found are anticorrelations with Alfven Mach number and electron beta. Mechanisms which might produce electron beams in the shock and magnetosheath are discussed in terms of the correlation study results. These mechanisms include acceleration by the cross-shock electric field and by lower hybrid frequency waves. A magnetosheath 'time of flight' mechanism, in analogy to the electron foreshock region, is introduced as another possible beam generation mechanism.

  7. High-speed OH* chemiluminescence imaging of ignition through a shock tube end-wall

    NASA Astrophysics Data System (ADS)

    Troutman, V. A.; Strand, C. L.; Campbell, M. F.; Tulgestke, A. M.; Miller, V. A.; Davidson, D. F.; Hanson, R. K.

    2016-03-01

    A high-speed OH* chemiluminescence imaging diagnostic was developed to image the structure and homogeneity of combustion events behind reflected shock waves in the Stanford Constrained Reaction Volume Shock Tube. An intensified high-repetition-rate imaging system was used to acquire images of OH* chemiluminescence (near 308 nm) through a fused quartz shock tube end-wall window at 10-33 kHz during the combustion of n-heptane (21 % O2/Ar, φ = 0.5). In general, the imaging technique enabled observation of the main ignition event in the core of the shock tube that corresponded to typical markers of ignition (e.g., pressure rise), as well as localized ignition near the wall that preceded the main core ignition event for some conditions. Case studies were performed to illustrate the utility of this novel imaging diagnostic. First, by comparing localized wall ignition events to the core ignition event, the temperature homogeneity of the post-reflected shock gas near the end-wall was estimated to be within 0.5 % for the test condition presented (T=1159 hbox {K}, P=0.25 hbox {MPa}). Second, the effect of a recession in the shock tube wall, created by an observation window, on the combustion event was visualized. Localized ignition was observed near the window, but this disturbance did not propagate to the core of the shock tube before the main ignition event. Third, the effect of shock tube cleanliness was investigated by conducting tests in which the shock tube was not cleaned for multiple consecutive runs. For tests after no cleaning was performed, ignition events were concentrated in the lower half of the shock tube. In contrast, when the shock tube was cleaned, the ignition event was distributed around the entire circumference of the shock tube; validating the cleaning procedure.

  8. Shock experiments and numerical simulations on low energy portable electrically exploding foil accelerators

    NASA Astrophysics Data System (ADS)

    Saxena, A. K.; Kaushik, T. C.; Gupta, Satish C.

    2010-03-01

    Two low energy (1.6 and 8 kJ) portable electrically exploding foil accelerators are developed for moderately high pressure shock studies at small laboratory scale. Projectile velocities up to 4.0 km/s have been measured on Kapton flyers of thickness 125 μm and diameter 8 mm, using an in-house developed Fabry-Pérot velocimeter. An asymmetric tilt of typically few milliradians has been measured in flyers using fiber optic technique. High pressure impact experiments have been carried out on tantalum, and aluminum targets up to pressures of 27 and 18 GPa, respectively. Peak particle velocities at the target-glass interface as measured by Fabry-Pérot velocimeter have been found in good agreement with the reported equation of state data. A one-dimensional hydrodynamic code based on realistic models of equation of state and electrical resistivity has been developed to numerically simulate the flyer velocity profiles. The developed numerical scheme is validated against experimental and simulation data reported in literature on such systems. Numerically computed flyer velocity profiles and final flyer velocities have been found in close agreement with the previously reported experimental results with a significant improvement over reported magnetohydrodynamic simulations. Numerical modeling of low energy systems reported here predicts flyer velocity profiles higher than experimental values, indicating possibility of further improvement to achieve higher shock pressures.

  9. High-Order Simulation of Non-Linear Oscillations and Shocks in the Solar Atmosphere

    NASA Technical Reports Server (NTRS)

    Bryson, S.; Kosovichev, A.; Levy, D.

    2004-01-01

    The solar atmosphere presents a rich source of highly non-linear magneto-hydrodynamic phenomena: strong gradients and forcing terms result in both large shocks and oscillations. The additional requirements of energy balance and initialization in hydrostatic equilibrium compound the challenge of this problem. A wealth of observational data allows us to check the results of our simulations. The problem of simulating the solar atmosphere provides, in addition to an interesting system in its own right, a challenging testbed for high-order shock-capturing methods. We discuss the challenge of simulating solar atmospheric phenomena, concentrating on various high-order central methods ranging from second to fourth order. Our method is based on the central-upwind scheme of Kurganov, Noelle and Petrova, which we extend to high order via various interpolants. We investigate various initial data for our simulations, corresponding to observed conditions in different regions of the solar surface: the normal quiet sun and sunspots. When non-oscillatory using second- and third-order methods, we are able to reproduce non-trivial observational results. In particular we find a correlation between initial data and both the shock speeds and particle oscillation spectra that match observations in the corresponding regions. When using fourth-order WENO interpolants, we find that while the individual shock profiles at any given time appear non-oscillatory, spurious oscillations appear in the fields after long time integrations. The issue of initialization in hydrostatic equilibrium raises difficult issues. Careful treatment of the gravitational source term can reduce violations of hydrostatic equilibrium, but difficulties remain, primarily due to discontinuities in the piecewise-polynomial reconstructions. In the case of the Euler equations in gravity, the use of high-order methods reduces the violation of hydrostatic equilibrium to a sufficiently low level for the above described results

  10. On the maximum energy achievable in the first order Fermi acceleration at shocks

    NASA Astrophysics Data System (ADS)

    Grozny, I.; Diamond, P.; Malkov, M.

    2002-11-01

    Astrophysical shocks are considered as the sites of cosmic ray (CR) production. The primary mechanism is the diffusive shock (Fermi) acceleration which operates via multiple shock recrossing by a particle. Its efficiency, the rate of energy gain, and the maximum energy are thus determined by the transport mechanisms (confinement to the shock) of these particles in a turbulent shock environment. The turbulence is believed to be generated by accelerated particles themselves. Moreover, in the most interesting case of efficient acceleration the entire MHD shock structure is dominated by their pressure. This makes this problem one of the challenging strongly nonlinear problems of astrophysics. We suggest a physical model that describes particle acceleration, shock structure and the CR driven turbulence on an equal footing. The key new element in this scheme is nonlinear cascading of the MHD turbulence on self-excited (via modulational and Drury instability) sound-like perturbations which gives rise to a significant enrichment of the long wave part of the MHD spectrum. This is critical for the calculation of the maximum energy.

  11. Shock Formation and Energy Dissipation of Slow Magnetosonic Waves in Coronal Plumes

    NASA Technical Reports Server (NTRS)

    Cuntz, M.; Suess, S. T.

    2003-01-01

    We study the shock formation and energy dissipation of slow magnetosonic waves in coronal plumes. The wave parameters and the spreading function of the plumes as well as the base magnetic field strength are given by empirical constraints mostly from SOHO/UVCS. Our models show that shock formation occurs at low coronal heights, i.e., within 1.3 bun, depending on the model parameters. In addition, following analytical estimates, we show that scale height of energy dissipation by the shocks ranges between 0.15 and 0.45 Rsun. This implies that shock heating by slow magnetosonic waves is relevant at most heights, even though this type of waves is apparently not a solely operating energy supply mechanism.

  12. Highly Shocked Low Density Sedimentary Rocks from the Haughton Impact Structure, Devon Island, Nunavut, Canada

    NASA Technical Reports Server (NTRS)

    Osinski, G. R.; Spray, J. G.

    2001-01-01

    We present the preliminary results of a detailed investigation of the shock effects in highly shocked, low density sedimentary rocks from the Haughton impact structure. We suggest that some textural features can be explained by carbonate-silicate immiscibility. Additional information is contained in the original extended abstract.

  13. Observational Evidence for High-Mach Number Regime of Coronal Shock Waves During Powerful Solar Particle Events

    NASA Astrophysics Data System (ADS)

    Rouillard, A. P.; Illya, P.; Zucca, P.; Tylka, A. J.; Vainio, R. O.; Vourlidas, A.

    2015-12-01

    Identifying the physical mechanisms that produce the most energetic particles is a long-standing observational and theoretical challenge in astrophysics. Strong shock waves have been proposed as efficient accelerators both in the solar physics and astrophysical contexts via various acceleration mechanisms. The proposed processes rely on shock waves being super-critical or moving several times faster than the characteristic speed of the medium they propagate through (a high MA). Using recent imaging of the NASA STEREO, SOHO and SDO spacecraft, we provide the first observations of the time-dependent 3-dimensional distribution of the expansion speed and MA of a coronal shock wave. These observations show that the high-energy particles measured near Earth are produced at the time of the sharp rise in the shock Mach number (>10) magnetically connected to Earth. These findings provide direct evidence to energetic particles being accelerated during the formation of a strong coronal shock. Using our new technique, we study the longitudinal spread and timing of a number of other energetic particle events during cycle 24.

  14. 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.

  15. Challenging shock models with SOFIA OH observations in the high-mass star-forming region Cepheus A

    NASA Astrophysics Data System (ADS)

    Gusdorf, A.; Güsten, R.; Menten, K. M.; Flower, D. R.; Pineau des Forêts, G.; Codella, C.; Csengeri, T.; Gómez-Ruiz, A. I.; Heyminck, S.; Jacobs, K.; Kristensen, L. E.; Leurini, S.; Requena-Torres, M. A.; Wampfler, S. F.; Wiesemeyer, H.; Wyrowski, F.

    2016-01-01

    Context. OH is a key molecule in H2O chemistry, a valuable tool for probing physical conditions, and an important contributor to the cooling of shock regions around high-mass protostars. OH participates in the re-distribution of energy from the protostar towards the surrounding Interstellar Medium. Aims: Our aim is to assess the origin of the OH emission from the Cepheus A massive star-forming region and to constrain the physical conditions prevailing in the emitting gas. We thus want to probe the processes at work during the formation of massive stars. Methods: We present spectrally resolved observations of OH towards the protostellar outflows region of Cepheus A with the GREAT spectrometer onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA) telescope. Three triplets were observed at 1834.7 GHz, 1837.8 GHz, and 2514.3 GHz (163.4 μm, 163.1 μm between the 2Π1/2 J = 1/2 states, and 119.2 μm, a ground transition between the 2Π3/2 J = 3/2 states), at angular resolutions of 16.̋3, 16.̋3, and 11.̋9, respectively. We also present the CO (16-15) spectrum at the same position. We compared the integrated intensities in the redshifted wings to the results of shock models. Results: The two OH triplets near 163 μm are detected in emission, but with blending hyperfine structure unresolved. Their profiles and that of CO (16-15) can be fitted by a combination of two or three Gaussians. The observed 119.2 μm triplet is seen in absorption, since its blending hyperfine structure is unresolved, but with three line-of-sight components and a blueshifted emission wing consistent with that of the other lines. The OH line wings are similar to those of CO, suggesting that they emanate from the same shocked structure. Conclusions: Under this common origin assumption, the observations fall within the model predictions and within the range of use of our model only if we consider that four shock structures are caught in our beam. Overall, our comparisons suggest that

  16. Supernova dynamics in the laboratory: Radiative shocks produced by ultra-high pressure implosion experiments on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Pak, Arthur

    2012-10-01

    Thermonuclear fuel experiments on the National Ignition Facility implode 2-mm diameter capsules with a cryogenic deuterium-tritium ice layer to 1000x liquid density and pressures exceeding 100 Gbar (10^11 atm). About 200 ps after peak compression, a spherical supernova-like radiative shock wave is observed that expands with shock velocities of uS = 300 km/s, temperatures of order 1 keV at densities of 1 g/cc resulting in a radiation strength parameter of Q ˜uS^5 = 10^4. Radiation-hydrodynamic simulations indicate that the shock launched at stagnation first goes down a strong density gradient while propagating outward from the highly compressed DT fuel (˜ 1000g/cc) to the ablation front (˜ 1 g/cc). Similar to what happens inside a star, the shock pressure drops as it accelerates and heats. The radiative shock emission is first observed when it breaks out of the dense compressed fuel shell into the low-density inflowing plasma at the ablation front mimicking the supernova situation where the shock breaks out through the star surface into surrounding in-falling matter [1,2]; the shock is subsequently approaching the supercritical state with a strong pre-cursor followed by rapid cooling. These observations are consistent with the rapid vanishing of the radiation ring 400 ps after peak compression due to strong radiation losses and spherical expansion. The evolution and brightness of the radiative shock provides insight into the performance of these implosions that have the goal to produce burning fusion plasmas in the laboratory. By modifying the capsule ablator composition and thickness, the stagnation pressure, density gradients, shock velocity and radiative properties could be tailored to study various regimes related to supernovae radiative remnants.[4pt] [1] W. David Arnett, Supernovae as phenomena of high-energy astrophysics, Ann NY Aca. Science 302, 90 (1977).[0pt] [2] L. Ensman and A. Burrows, Shock breakout in SN1987A, ApJ 393, 742.

  17. DIFFUSIVE PARTICLE ACCELERATION IN SHOCKED, VISCOUS ACCRETION DISKS: GREEN'S FUNCTION ENERGY DISTRIBUTION

    SciTech Connect

    Becker, Peter A.; Das, Santabrata; Le, Truong E-mail: sbdas@iitg.ernet.in

    2011-12-10

    The acceleration of relativistic particles in a viscous accretion disk containing a standing shock is investigated as a possible explanation for the energetic outflows observed around radio-loud black holes. The energy/space distribution of the accelerated particles is computed by solving a transport equation that includes the effects of first-order Fermi acceleration, bulk advection, spatial diffusion, and particle escape. The velocity profile of the accreting gas is described using a model for shocked viscous disks recently developed by the authors, and the corresponding Green's function distribution for the accelerated particles in the disk and the outflow is obtained using a classical method based on eigenfunction analysis. The accretion-driven, diffusive shock acceleration scenario explored here is conceptually similar to the standard model for the acceleration of cosmic rays at supernova-driven shocks. However, in the disk application, the distribution of the accelerated particles is much harder than would be expected for a plane-parallel shock with the same compression ratio. Hence the disk environment plays a key role in enhancing the efficiency of the shock acceleration process. The presence of the shock helps to stabilize the disk by reducing the Bernoulli parameter, while channeling the excess binding energy into the escaping relativistic particles. In applications to M87 and Sgr A*, we find that the kinetic power in the jet is {approx}0.01 M-dot c{sup 2}, and the outflowing relativistic particles have a mean energy {approx}300 times larger than that of the thermal gas in the disk at the shock radius. Our results suggest that a standing shock may be an essential ingredient in accretion onto underfed black holes, helping to resolve the long-standing problem of the stability of advection-dominated accretion disks.

  18. High-Speed OH* Chemiluminescence Imaging of Shock Tube End-Wall

    NASA Astrophysics Data System (ADS)

    Troutman, V. A.; Miller, V. A.; Strand, C. S.; Tulgestke, A. M.; Campbell, M. F.; Davidson, D. F.; Hanson, R. K.

    2015-11-01

    We have developed a high-speed OH* chemiluminesence imaging diagnostic and a transparent end-wall for the Stanford Aerosol Shock Tube to better understand the structure and homogeneity of the combustion event behind a reflected shock wave. We use an intensified high repetition rate imaging system to acquire images of OH* chemiluminescence (near 308 nm) at 10-33 kHz from n-heptane combustion. Case studies are presented to illustrate the power of this novel imaging diagnostic: first, we infer the temperature homogeneity of the ignition event; then we image the effect of surface imperfections in the wall of the shock tube; lastly, we visualize the effect of particulates in the shock tube and verify the importance of shock tube cleaning routines.

  19. Heat flux and shock shape measurements on an Aeroassist Flight Experiment model in a high enthalpy free piston shock tunnel

    NASA Technical Reports Server (NTRS)

    Gai, S. L.; Mudford, N. R.; Hackett, C.

    1992-01-01

    This paper describes measurements of heat flux and shock shapes made on a 2.08 percent scale model of the proposed Aeroassist Flight Experiment model in a high enthalpy free piston shock tunnel T3 at the Australian National University in Canberra, Australia. The enthalpy and Reynolds number range covered were 7.5 MJ/kg to 20 MJ/kg and 150,000 to 270,000 per meter respectively. The test Mach number varied between 7.5 and 8. Two test gases, air and nitrogen, were used and the model angle of attack varied from -10 deg to +10 deg to the free stream. The results are discussed and compared to the Mach 10 cold hypersonic air data as obtained in the Langley 31 inch Mach 10 Facility as well as the perfect gas CFD calculations of NASA LaRC.

  20. Frequency modulation in shock wave-boundary layer interaction by repetitive-pulse laser energy deposition

    NASA Astrophysics Data System (ADS)

    Tamba, T.; Pham, H. S.; Shoda, T.; Iwakawa, A.; Sasoh, A.

    2015-09-01

    Modulation of shock foot oscillation due to energy deposition by repetitive laser pulses in shock wave-boundary layer interaction over an axisymmetric nose-cylinder-flare model in Mach 1.92 flow was experimentally studied. From a series of 256 schlieren images, density oscillation spectra at each pixel were obtained. When laser pulses of approximately 7 mJ were deposited with a repetition frequency, fe, of 30 kHz or lower, the flare shock oscillation had a peak spectrum equivalent to the value of fe. However, with fe of 40 kHz-60 kHz, it experienced frequency modulation down to lower than 20 kHz.

  1. Extracorporeal stone disintegration using chemical explosive pellets as an energy source of underwater shock waves.

    PubMed

    Kuwahara, M; Kambe, K; Kurosu, S; Orikasa, S; Takayama, K

    1986-04-01

    Extracorporeal renal stone disintegration using a chemical explosive pellet (lead azide 10 mg.) as an energy source of underwater shock waves has been successfully performed in animals. The shock wave was observed by holographic interferometry. Shock wave generation was performed by a reflector whose configuration was part of a pseudoellipsoid. The explosions were conducted 10 to 100 times for each animal and the stone (extracted human renal calculus or model calculus of activated alumina) placed in the renal pelvis was disintegrated satisfactorily. Negative findings in explorative laparotomy and histological examination, except for minor bleeding in several tubular lumina of the kidney, indicated that the method was clinically applicable. PMID:3959213

  2. High density turbulent plasma processes from a shock tube. Final performance report

    SciTech Connect

    Johnson, J.A. III

    1997-01-01

    A broad-based set of measurements has begun on high density turbulent plasma processes. This includes determinations of new plasma physics and the initiation of work on new diagnostics for collisional plasmas as follows: (1) 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. (2) Point fluorescence emissions and averaged spectral line evolutions in turbulent plasmas produced in both the primary and the reflected shock wave flows exhibit ergodicity in the standard turbulence parameters. The data show first evidence of a reverse energy cascade in the collisional turbulent plasma. This suggests that the fully turbulent environment can be described using a stationary state formulation. In these same data, the author finds compelling evidence for a turbulent Stark effect on neutral emission lines in these data which is associated with evidence of large coherent structures and dominant modes in the Fourier analyses of the fluctuations in the optical spectra. (3) A neutral beam generator has been assembled by coupling a Colutron Ion Gun to a charge exchange chamber. Beam-target collisions where the target species is neutral and the beam is either singly charged or neutral have been performed using argon as the working gas. Spectral analysis of the emission shows specific radiative transitions characteristic of both Ar I and Ar II, indicating that some ionization of the target gas results. Gas and plasma parameters such as density, pressure, temperature and flow velocity and their fluctuations can now be followed in real time by spectroscopic analysis of carefully chosen radiative emissions.

  3. Effect of electronic excitation on high-temperature flows behind strong shock waves

    SciTech Connect

    Istomin, V. A.; Kustova, E. V.

    2014-12-09

    In the present paper, a strongly non-equilibrium one-dimensional steady-state flow behind the plane shock wave is studied. We consider a high-temperature chemically reacting five-component ionized mixture of nitrogen species (N{sub 2}/N{sub 2}{sup 2}/N/N{sup +}/e{sup −}) taking into account electronic degrees of freedom in N and N{sup +} (170 and 625 electronic energy levels respectively), and electronic-rotational-vibrational modes in N{sub 2} and N{sub 2}{sup +} (5 and 7 electronic terms). Non-equilibrium reactions of ionization, dissociation, recombination and charge-transfer are included to the kinetic scheme. The system of governing equations is written under the assumption that translation and internal energy relaxation is fast whereas chemical reactions and ionization proceed on the macroscopic gas-dynamics time-scale. The developed model is applied to simulate the flow behind a plane shock wave under initial conditions characteristic for the spacecraft re-entry from an interplanetary flight (Hermes and Fire II experiments). Fluid-dynamic parameters behind the shock wave as well as transport coefficients and the heat flux are calculated for the (N{sub 2}/N{sub 2}{sup +}/N/N{sup +}/e{sup −}) mixture. The effect of electronic excitation on kinetics, dynamics and heat transfer is analyzed. Whereas the contribution of electronic degrees of freedom to the flow macroparameters is negligible, their influence on the heat flux is found to be important under conditions of Hermes re-entry.

  4. High shock, high frequency characteristics of a mechanical isolator for a piezoresistive accelerometer

    SciTech Connect

    Bateman, V.I.; Brown, F.A.; Davie, N.T.

    1995-07-01

    A mechanical isolator has been developed for a piezoresistive accelerometer. The purpose of the isolator is to mitigate high frequency shocks before they reach the accelerometer because the high frequency shocks may cause the accelerometer to resonate. Since the accelerometer is undamped, it often breaks when it resonates. The mechanical isolator was developed in response to impact test requirements for a variety of structures at Sandia National Laboratories. An Extended Technical Assistance Program with the accelerometer manufacturer has resulted in a commercial isolator that will be available to the general public. This mechanical isolator has ten times the bandwidth of any other commercial isolator and has acceptable frequency domain performance from DC to 10 kHz ({plus_minus} 10%) over a temperature range of -65{degrees}F to +185{degrees}F as demonstrated in this paper.

  5. Properties of planetary fluids at high shock pressures and temperatures

    SciTech Connect

    Nellis, W.J.; Mitchell, A.C.; Holmes, N.C.; McCandless, P.C.

    1991-03-01

    Models of the interiors of Uranus and Neptune are discussed. Pressures and temperatures in the interiors can be achieved in representative constituent molecular fluids by shock compression. Experimental techniques are described and recent results for synthetic Uranus and hydrogen are discussed. 19 refs., 4 figs., 1 tab.

  6. Surprisingly high-pressure shocks in the supernova remnant IC 443

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The intensities of several lines of molecular hydrogen have been measured from two regions of the supernova-remnant/molecular-cloud shock in IC 443. The lines measured have upper-state energies ranging from 7000 K to 23,000 K. Their relative intensities differ in the two regions, but are consistent with those predicted from the post-shock regions of simple jump-type shocks of different pressure. The pressures so derived are far higher than the pressure in the supernova remnant itself, and a possible reason for this discrepancy is discussed.

  7. Pseudo-shock waves and their interactions in high-speed intakes

    NASA Astrophysics Data System (ADS)

    Gnani, F.; Zare-Behtash, H.; Kontis, K.

    2016-04-01

    In an air-breathing engine the flow deceleration from supersonic to subsonic conditions takes places inside the isolator through a gradual compression consisting of a series of shock waves. The wave system, referred to as a pseudo-shock wave or shock train, establishes the combustion chamber entrance conditions, and therefore influences the performance of the entire propulsion system. The characteristics of the pseudo-shock depend on a number of variables which make this flow phenomenon particularly challenging to be analysed. Difficulties in experimentally obtaining accurate flow quantities at high speeds and discrepancies of numerical approaches with measured data have been readily reported. Understanding the flow physics in the presence of the interaction of numerous shock waves with the boundary layer in internal flows is essential to developing methods and control strategies. To counteract the negative effects of shock wave/boundary layer interactions, which are responsible for the engine unstart process, multiple flow control methodologies have been proposed. Improved analytical models, advanced experimental methodologies and numerical simulations have allowed a more in-depth analysis of the flow physics. The present paper aims to bring together the main results, on the shock train structure and its associated phenomena inside isolators, studied using the aforementioned tools. Several promising flow control techniques that have more recently been applied to manipulate the shock wave/boundary layer interaction are also examined in this review.

  8. Characterization of a High Temporal Resolution TDLAS System for Measurements in a Shock Tube Facility

    NASA Astrophysics Data System (ADS)

    Förster, F.; O'Byrne, Sean; Kleine, H.; Weigand, B.

    Transient heating and pressurization of a gas by shock waves can be useful for a variety of purposes, particularly for configurations involving shock wave focussing. Unless the geometry is particularly simple, the time history of temperature can be difficult to predict accurately. Hence, a non-intrusive measurement technique with high temporal resolution is required to record the time history of the very rapidly changing temperature of a shock-heated flow. One promising measurement techniques for these high-speed flows is Tunable Diode Laser Absorption Spectroscopy (TDLAS)

  9. Studying astrophysical collisionless shocks with counterstreaming plasmas from high power lasers

    NASA Astrophysics Data System (ADS)

    Park, Hye-Sook; Ryutov, D. D.; Ross, J. S.; Kugland, N. L.; Glenzer, S. H.; Plechaty, C.; Pollaine, S. M.; Remington, B. A.; Spitkovsky, A.; Gargate, L.; Gregori, G.; Bell, A.; Murphy, C.; Sakawa, Y.; Kuramitsu, Y.; Morita, T.; Takabe, H.; Froula, D. H.; Fiksel, G.; Miniati, F.; Koenig, M.; Ravasio, A.; Pelka, A.; Liang, E.; Woolsey, N.; Kuranz, C. C.; Drake, R. P.; Grosskopf, M. J.

    2012-03-01

    Collisions of high Mach number flows occur frequently in astrophysics, and the resulting shock waves are responsible for the properties of many astrophysical phenomena, such as supernova remnants, Gamma Ray Bursts and jets from Active Galactic Nuclei. Because of the low density of astrophysical plasmas, the mean free path due to Coulomb collisions is typically very large. Therefore, most shock waves in astrophysics are "collisionless", since they form due to plasma instabilities and self-generated magnetic fields. Laboratory experiments at the laser facilities can achieve the conditions necessary for the formation of collisionless shocks, and will provide a unique avenue for studying the nonlinear physics of collisionless shock waves. We are performing a series of experiments at the Omega and Omega-EP lasers, in Rochester, NY, with the goal of generating collisionless shock conditions by the collision of two high-speed plasma flows resulting from laser ablation of solid targets using ˜1016 W/cm2 laser irradiation. The experiments will aim to answer several questions of relevance to collisionless shock physics: the importance of the electromagnetic filamentation (Weibel) instabilities in shock formation, the self-generation of magnetic fields in shocks, the influence of external magnetic fields on shock formation, and the signatures of particle acceleration in shocks. Our first experiments using Thomson scattering diagnostics studied the plasma state from a single foil and from double foils whose flows collide "head-on". Our data showed that the flow velocity and electron density were 108 cm/s and 1019 cm-3, respectively, where the Coulomb mean free path is much larger than the size of the interaction region. Simulations of our experimental conditions show that weak Weibel mediated current filamentation and magnetic field generation were likely starting to occur. This paper presents the results from these first Omega experiments.

  10. High-Precision Measurements of the Equation of State of Polymers at 100 to 1000 GPa Using Laser-Driven Shock Waves

    NASA Astrophysics Data System (ADS)

    Barrios, M. A.

    2009-11-01

    The equation of state (EOS) of materials at extreme temperatures and pressures is of interest to astrophysics, high-energy-density physics, and inertial confinement fusion (ICF). The high-pressure (>100 GPa) behavior of polymer materials is essential to the understanding of ablator materials for ignition targets. EOS measurements on CHx provide benchmarks on the behavior of polymers under extreme conditions and the effect of stoichiometry (i.e., the C:H ratio) on that behavior. High-power lasers produce shock pressures greater than 100 GPa, and recent advances in diagnostics and analysis have made it possible to perform highly accurate measurements of shock velocity. This improves upon the impedance-matching technique for laser-driven shock experiments, producing ˜1% precision at extreme pressures. The OMEGA laser is used to produce principal (single-shock) Hugoniot EOS measurements on polystyrene (CH), polypropylene (CH2), GDP (C43H56O), and Ge-doped GDP at shock pressures of ˜100 to 1000 GPa. We also present a novel target design that provides double-shock (re-shock) data together with the above data. These data are pertinent to ICF target designs that use multiple shocks to approximate an isentropic compression. Results of the single- and double-shock experiments on these polymers are presented and compared to various EOS models. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302. In collaboration with T.R. Boehly, D.E. Fratanduono, D.D. Meyerhofer (LLE), D.G. Hicks, P.M. Celliers, and G.W. Collins (LLNL).

  11. Shock compression and release in high-strength ceramics

    SciTech Connect

    Kipp, M E; Grady, D E

    1989-08-01

    A preliminary investigation of shock compression and release properties has been performed on four ceramics: silicon carbide, titanium diboride, boron carbide and zirconium dioxide. Eight planar impact experiments using thin discs of similar ceramic as impactor and target have been completed. The particle velocity history at the interface between the back of the target ceramic and a lithium fluoride window material was acquired with a laser velocity interferometer (VISAR). These wave profiles indicate that each of these materials responds in a unique way to shock loading. Peak impact stresses in these experiments range between 20 and 50 GPa, leading to pronounced permanent deformation behavior of these materials. Dynamic compression and release stress-strain behavior of the ceramics, formulated with numerical iteration methods, is compared with compressive strength properties determined from the experimental data. The current experiments provide data for these ceramic materials which can be used to evaluate computational material models in wave propagation codes. 23 refs., 25 figs., 4 tabs.

  12. Second application of low-energy shock waves has a cumulative effect on free nerve endings.

    PubMed

    Takahashi, Norimasa; Ohtori, Seiji; Saisu, Takashi; Moriya, Hideshige; Wada, Yuichi

    2006-02-01

    Some physicians recommend treating tendinopathies with multiple sessions of shock waves. Some evidence, however, suggests shock wave application can induce nerve fiber degeneration. We questioned whether repeated shock wave application provides a cumulative effect on nerve fibers compared with the effect of one application. One thousand shock wave impulses of an energy flux density of 0.08 mJ/mm were applied to the foot pad of 32 rats. After 14 days, 16 rats received a second application. The foot pads were resected on Days 7, 14, 28, and 42. Sections were processed immunohistochemically using antibodies for sensory nerve. We compared the number of epidermal nerve fibers in rats that received one application of shock waves with the fibers in rats that received two applications. During the first 4 weeks, there was nearly complete degeneration of epidermal nerve fibers in both groups. By the end of 6 weeks, reinnervation of the epidermis began in the single-treatment group. Reinnervation occurred slower in the repeated-treatment group. These data show that a second application has a cumulative effect on nerve fibers. Our data suggest multiple applications of low-energy shock waves might a provide longer-lasting antinociceptive effect. PMID:16462457

  13. Molecular and planetary fluids at high shock pressures

    SciTech Connect

    Nellis, W.J.; Mitchell, A.C.

    1998-07-01

    Shock-compression experiments on liquids using a two-stage gun are described. Results for H{sub 2}, He, H{sub 2}O, N{sub 2}, CO{sub 2}, and a mixture of H{sub 2}O, NH{sub 3}, and C{sub 3}H{sub 8}O (synthetic Uranus) are discussed and related to explosive reaction products, giant planets, laser-driven fusion, and metallic hydrogen. {copyright} {ital 1998 American Institute of Physics.}

  14. Simulating radiative shocks in nozzle shock tubes

    NASA Astrophysics Data System (ADS)

    van der Holst, B.; Tóth, G.; Sokolov, I. V.; Daldorff, L. K. S.; Powell, K. G.; Drake, R. P.

    2012-06-01

    We use the recently developed Center for Radiative Shock Hydrodynamics (CRASH) code to numerically simulate laser-driven radiative shock experiments. These shocks are launched by an ablated beryllium disk and are driven down xenon-filled plastic tubes. The simulations are initialized by the two-dimensional version of the Lagrangian Hyades code which is used to evaluate the laser energy deposition during the first 1.1 ns. Later times are calculated with the CRASH code. CRASH solves for the multi-material hydrodynamics with separate electron and ion temperatures on an Eulerian block-adaptive-mesh and includes a multi-group flux-limited radiation diffusion and electron thermal heat conduction. The goal of the present paper is to demonstrate the capability to simulate radiative shocks of essentially three-dimensional experimental configurations, such as circular and elliptical nozzles. We show that the compound shock structure of the primary and wall shock is captured and verify that the shock properties are consistent with order-of-magnitude estimates. The synthetic radiographs produced can be used for comparison with future nozzle experiments at high-energy-density laser facilities.

  15. Forward acoustic performance of a shock-swallowing high-tip-speed fan (QF-13)

    NASA Technical Reports Server (NTRS)

    Lucas, J. G.; Woodward, R. P.; Mackinnon, M. J.

    1980-01-01

    Forward noise and overall aerodynamic performance data are presented for a high-tip-speed fan having rotor blade airfoils designed to alter the conventional leading-edge bow shocks to weak, oblique shocks which are swallowed within the interblade channels. It was anticipated that the swallowed shocks would minimize the generation of multiple-pure-tone noise. In the speed range where the shocks presumably were swallowed, the multiple-tone noise was lowered only about 3 decibels. Comparison with several high-speed fans on a thrust-corrected basis indicates that the present fan was the quietest in total forward noise at low speeds but offered no advantage at high speeds.

  16. Shocks in the solar wind between 1 and 8.5 AU: Voyager 1 observations

    NASA Technical Reports Server (NTRS)

    Gazis, P. R.

    1984-01-01

    A survey was made of all interplanetary shocks detected by the plasma science experiment aboard the Voyager 1 spacecraft between 1.2 and 8.5 AU. Shock normals and shock velocities are determined. The variation of shock frequency and various shock parameters with heliocentric distance is discussed. The results indicate that beyond 1.2 AU, the vast majority of shocks were associated with interaction regions between high and low speed streams; of 95 events, only 1 was clearly associated with a transient event. Forward shocks were more numerous and seemed to form closer to the sun than reverse shocks. Forward shocks were stronger than reverse shocks. The energy balance of three shocks is examined. A close agreement is found between the measured and the predicted pressure ratios across these shocks. The contribution of shocks to the global energy balance is discussed. Shocks are found to have a significant effect in heating the solar wind.

  17. High energy neutron radiography

    SciTech Connect

    Gavron, A.; Morley, K.; Morris, C.; Seestrom, S.; Ullmann, J.; Yates, G.; Zumbro, J.

    1996-06-01

    High-energy spallation neutron sources are now being considered in the US and elsewhere as a replacement for neutron beams produced by reactors. High-energy and high intensity neutron beams, produced by unmoderated spallation sources, open potential new vistas of neutron radiography. The authors discuss the basic advantages and disadvantages of high-energy neutron radiography, and consider some experimental results obtained at the Weapons Neutron Research (WNR) facility at Los Alamos.

  18. A fail-safe magnetorheological energy absorber for shock and vibration isolation

    SciTech Connect

    Bai, Xian-Xu; Wereley, Norman M.

    2014-05-07

    Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control.

  19. A fail-safe magnetorheological energy absorber for shock and vibration isolation

    NASA Astrophysics Data System (ADS)

    Bai, Xian-Xu; Wereley, Norman M.

    2014-05-01

    Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control.

  20. Mesoscopic simulations of shock-to-detonation transition in reactive liquid high explosive

    NASA Astrophysics Data System (ADS)

    Maillet, J. B.; Bourasseau, E.; Desbiens, N.; Vallverdu, G.; Stoltz, G.

    2011-12-01

    An extension of the model described in a previous work (see Maillet J. B. et al., EPL, 78 (2007) 68001) based on Dissipative Particle Dynamics is presented and applied to a liquid high explosive (HE), with thermodynamic properties mimicking those of liquid nitromethane. Large scale nonequilibrium simulations of reacting liquid HE with model kinetic under sustained shock conditions allow a better understanding of the shock-to-detonation transition in homogeneous explosives. Moreover, the propagation of the reactive wave appears discontinuous since ignition points in the shocked material can be activated by the compressive waves emitted from the onset of chemical reactions.

  1. Shock fitting applied to the prediction of high-speed rotor noise

    NASA Technical Reports Server (NTRS)

    Rutherford, J. W.

    1985-01-01

    A shock fitting method applied to the transonic small disturbance (TSD) potential equation is described. This method is then applied to a simple, two dimensional (2-D) rotating disturbance which is analogous to a shock radiating from the tip of a rotor blade in high speed hover. A comparison is made between the results of this method and the more standard shock capturing method. This comparison makes it clear that the effect of the results on the acoustic signature of the 2-D model is significant, and similar results can be expected when the method is extended to the three dimensional (3-D) case.

  2. High-g shock test results of Tadiran TLM-1530MP cells.

    SciTech Connect

    O'Malley, Patrick D.

    2009-06-01

    In April of 2009, testing was done of a high-g instrumentation device that utilized Tadiran TLM-1530MP cells as a power source. As a result of that testing, it was determined that those cells exhibit failure more often when shocked in the axial direction. No failures over many tests where found when the cells were shocked laterally. Moreover, when shocked laterally, the cells exhibited no observable degradation in performance. We looked at the failed cells via non-destructive x-ray analysis to determine what internal structures failed.

  3. APPARATUS FOR PRODUCING HIGH VELOCITY SHOCK WAVES IN GASES

    DOEpatents

    Scott, F.R.; Josephson, V.

    1960-02-01

    >A device for producing a high-energy ionized gas region comprises an evacuated tapered insulating vessel and a substantially hemispherical insulating cap hermetically affixed to the large end of the vessel, an annular electrode having a diameter equal to and supported in the interior wall of the vessel at the large end and having a conductive portion inside the vessel, a second electrode supported at the small end of the vessel, means connected to the vessel for introducing a selected gas therein, a source of high potential having two poles. means for connecting one pole of the high potential source to the annular electrode, and means for connecting the other pole of the potential source to the second electrode.

  4. The adiabatic energy change of plasma electrons and the frame dependence of the cross-shock potential at collisionless magnetosonic shock waves

    NASA Technical Reports Server (NTRS)

    Goodrich, C. C.; Scudder, J. D.

    1984-01-01

    The adiabatic energy gain of electrons in the stationary electric and magnetic field structure of collisionless shock waves was examined analytically in reference to conditions of the earth's bow shock. The study was performed to characterize the behavior of electrons interacting with the cross-shock potential. A normal incidence frame (NIF) was adopted in order to calculate the reversible energy change across a time stationary shock, and comparisons were made with predictions made by the de Hoffman-Teller (HT) model (1950). The electron energy gain, about 20-50 eV, is demonstrated to be consistent with a 200-500 eV potential jump in the bow shock quasi-perpendicular geometry. The electrons lose energy working against the solar wind motional electric field. The reversible energy process is close to that modeled by HT, which predicts that the motional electric field vanishes and the electron energy gain from the electric potential is equated to the ion energy loss to the potential.

  5. High Energy Density Studies at the OMEGA laser facility

    NASA Astrophysics Data System (ADS)

    Boehly, Thomas

    2015-06-01

    The primary emphasis of the scientific program at the Laboratory for Laser Energetics is laser-driven inertial confinement fusion. We report on high-energy-density (HED) experiments that use the OMEGA laser to produce multi-megabar shocks in materials of interest to the national fusion effort and the associated HED sciences. We present measurements of the behavior of shocked diamond, in both the single-crystal and ultranano-crystalline forms used as an ablator material in fusion capsules. Using the impedance-matching technique both the Hugoniot and release behaviors are measured with respect to multiple reference materials. The release of shocked diamond into liquid deuterium is also measured. We present the results of sound-speed measurements in shocked quartz which is also used as a reference for sound speed measurements in CH and fused silica. This is done using an unsteady wave analysis that tracks the propagation of small perturbations in shock pressure as they traverse the shocked material from `piston' to shock front. The arrival times of these perturbations, as compared to the same in a reference material, provides the sound speed in the shock material. We also present results of optical and x-ray probing of shock waves in foam targets and solid targets, as well as the release plumes of shock material after shock breakout. The import of these measurements to the fusion program and basic HED science will be discussed and plans for future work presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

  6. High pressure nano-crystalline microstructure of shock compressed single crystal iron

    SciTech Connect

    Hawreliak, J; Kalantar, D; Stolken, J; Remington, B; Lorenzana, H; Wark, J

    2007-12-11

    We discuss the first grain size measurements made during shock compression using in situ x-ray diffraction. Our experiments have shown unambiguously that single crystal iron shock loaded above 13 GPa along the [100] direction will transform from the ambient {alpha}-phase (BCC) to a highly ordered polycrystalline {epsilon}-phase (HCP). Here, we present a detailed shape analysis of the diffraction peaks using a modified Warren-Averbach method to quantify the microstructure of shock compressed high pressure iron. The {epsilon}-phase was determined through this method to have grain sizes between of 2 and 15 nm, in reasonable agreement with results from large scale MD simulations. We conclude that single crystal iron becomes nano-crystalline in shock transforming from the {alpha} to {epsilon} phase.

  7. Proton radiography experiments on shocked high explosive products.

    SciTech Connect

    Ferm, Eric N.; Dennsion, Steve; Lopez, Robert; Prestridge, Kathy; Quintana, John P.; Espinoza, Camilo; King, Gary Hogan Nick; Merrill, Frank; Kevin Morley,; Morris, Christopher L.; Pazuchanic, Peter

    2003-07-22

    We studied the propagation of detonation waves and reflections of normal incident detonation waves in explosive products using the 800 MeV proton radiography facility at LANSCE. Using this system, we obtain seven to twenty-one radiographic images of each experiment. We have examined the experimental wave velocity and density of the materials ahead and behind of the shocks as inferred from radiographs and compare them to standard explosive equations of state. Finally we compare the experiments with calculations of the experiments using the MESA hydrodynamics code.

  8. Electron acceleration in a wavy shock front

    NASA Astrophysics Data System (ADS)

    Vandas, M.; Karlický, M.

    2011-07-01

    Context. It is known that electrons are accelerated at nearly perpendicular shocks by the drift mechanism. And it is also known that energy gain of electrons caused by this mechanism is not very high. Therefore it was suggested in the past that the energy gain might be increased if shocks had wavy fronts. For instance, there were attempts to explain coronal type II burst and their fine structure by electron acceleration in a wavy shock front. Aims: We studied electron acceleration numerically at nearly perpendicular wavy shocks for coronal conditions and compared it with analytical results on electron acceleration at nearly perpendicular plane shocks. Methods: An analytical model of a wavy shock front was used and trajectories of electrons in it and around it were calculated numerically in a guiding centre approximation. Results: We found that energy gains of electrons at a wavy shock front and a corresponding smoothed-into-plane shock on the average were comparable. That is why they do not depend significantly on the shock thickness, magnetic field profile inside the shock, and shock wavy form. They do depend on the angle between the smoothed shock front and ambient magnetic field. Conclusions: On average, a wavy shock front does not significantly increase an acceleration efficiency. Energy gain remarkably exceeds an average level for some combinations of initial parameters. Distribution functions of accelerated electrons have a patchy structure, which is prone to inducing plasma instabilities that will generate plasma waves. This may have relevance to the problem of type II burst origin.

  9. Modeling of dissociation and energy transfer in shock-heated nitrogen flows

    SciTech Connect

    Munafò, A.; Liu, Y.; Panesi, M.

    2015-12-15

    This work addresses the modeling of dissociation and energy transfer processes in shock heated nitrogen flows by means of the maximum entropy linear model and a newly proposed hybrid bin vibrational collisional model. Both models aim at overcoming two of the main limitations of the state of the art non-equilibrium models: (i) the assumption of equilibrium between rotational and translational energy modes of the molecules and (ii) the reliance on the quasi-steady-state distribution for the description of the population of the internal levels. The formulation of the coarse-grained models is based on grouping the energy levels into bins, where the population is assumed to follow a Maxwell-Boltzmann distribution at its own temperature. Different grouping strategies are investigated. Following the maximum entropy principle, the governing equations are obtained by taking the zeroth and first-order moments of the rovibrational master equations. The accuracy of the proposed models is tested against the rovibrational master equation solution for both flow quantities and population distributions. Calculations performed for free-stream velocities ranging from 5 km/s to 10 km/s demonstrate that dissociation can be accurately predicted by using only 2-3 bins. It is also shown that a multi-temperature approach leads to an under-prediction of dissociation, due to the inability of the former to account for the faster excitation of high-lying vibrational states.

  10. Modeling of dissociation and energy transfer in shock-heated nitrogen flows

    NASA Astrophysics Data System (ADS)

    Munafò, A.; Liu, Y.; Panesi, M.

    2015-12-01

    This work addresses the modeling of dissociation and energy transfer processes in shock heated nitrogen flows by means of the maximum entropy linear model and a newly proposed hybrid bin vibrational collisional model. Both models aim at overcoming two of the main limitations of the state of the art non-equilibrium models: (i) the assumption of equilibrium between rotational and translational energy modes of the molecules and (ii) the reliance on the quasi-steady-state distribution for the description of the population of the internal levels. The formulation of the coarse-grained models is based on grouping the energy levels into bins, where the population is assumed to follow a Maxwell-Boltzmann distribution at its own temperature. Different grouping strategies are investigated. Following the maximum entropy principle, the governing equations are obtained by taking the zeroth and first-order moments of the rovibrational master equations. The accuracy of the proposed models is tested against the rovibrational master equation solution for both flow quantities and population distributions. Calculations performed for free-stream velocities ranging from 5 km/s to 10 km/s demonstrate that dissociation can be accurately predicted by using only 2-3 bins. It is also shown that a multi-temperature approach leads to an under-prediction of dissociation, due to the inability of the former to account for the faster excitation of high-lying vibrational states.

  11. OT1_pappleto_1: Charting the Cooling Pathways in High-Speed Extragalactic Shocks

    NASA Astrophysics Data System (ADS)

    Appleton, P.

    2010-07-01

    Following in the footsteps of ISO, recent observations with Spitzer have revealed a population of galaxy systems which emit a huge amount of luminosity in their pure rotational mid-IR molecular hydrogen lines, in some cases reaching 10-30 percent of the bolometric luminosity. These large line-luminosities are believed to be powered by galactic-scale shocks, which efficiently transfer kinetic energy to smaller dense clouds in the turbulent post-shock medium. However, nothing at all is known about the other important cooling channels for the shocked gas, such as [OI], H2O, OH, and CO, some of which can rival H2 as a coolant. We propose deep PACS and SPIRE spectroscopy of the Giant Shock in Stephan's Quintet and the Taffy Galaxy bridge to quantify the most important cooling channels and determine the physical state of the gas being shocked. The results have implications for understanding the importance of molecular cooling at higher redshift where turbulence and shock-heating may play a role in galaxy formation.

  12. Selfsimilar time dependent shock structures

    NASA Technical Reports Server (NTRS)

    Beck, R.; Drury, L. O.

    1985-01-01

    Diffusive shock acceleration as an astrophysical mechanism for accelerating charged particles has the advantage of being highly efficient. This means however that the theory is of necessity nonlinear; the reaction of the accelerated particles on the shock structure and the acceleration process must be self-consistently included in any attempt to develop a complete theory of diffusive shock acceleration. Considerable effort has been invested in attempting, at least partially, to do this and it has become clear that in general either the maximum particle energy must be restricted by introducing additional loss processes into the problem or the acceleration must be treated as a time dependent problem (Drury, 1984). It is concluded that stationary modified shock structures can only exist for strong shocks if additional loss processes limit the maximum energy a particle can attain. This is certainly possible and if it occurs the energy loss from the shock will lead to much greater shock compressions. It is however equally possible that no such processes exist and we must then ask what sort of nonstationary shock structure develops. The ame argument which excludes stationary structures also rules out periodic solutions and indeed any solution where the width of the shock remains bounded. It follows that the width of the shock must increase secularly with time and it is natural to examine the possibility of selfsimilar time dependent solutions.

  13. Selfsimilar time dependent shock structures

    NASA Astrophysics Data System (ADS)

    Beck, R.; Drury, L. O.

    1985-08-01

    Diffusive shock acceleration as an astrophysical mechanism for accelerating charged particles has the advantage of being highly efficient. This means however that the theory is of necessity nonlinear; the reaction of the accelerated particles on the shock structure and the acceleration process must be self-consistently included in any attempt to develop a complete theory of diffusive shock acceleration. Considerable effort has been invested in attempting, at least partially, to do this and it has become clear that in general either the maximum particle energy must be restricted by introducing additional loss processes into the problem or the acceleration must be treated as a time dependent problem (Drury, 1984). It is concluded that stationary modified shock structures can only exist for strong shocks if additional loss processes limit the maximum energy a particle can attain. This is certainly possible and if it occurs the energy loss from the shock will lead to much greater shock compressions. It is however equally possible that no such processes exist and we must then ask what sort of nonstationary shock structure develops. The ame argument which excludes stationary structures also rules out periodic solutions and indeed any solution where the width of the shock remains bounded. It follows that the width of the shock must increase secularly with time and it is natural to examine the possibility of selfsimilar time dependent solutions.

  14. Experimental Investigation of Primary and Secondary Features in High-Mach-Number Shock-Bubble Interaction

    NASA Astrophysics Data System (ADS)

    Ranjan, Devesh; Niederhaus, John; Motl, Bradley; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo

    2007-01-01

    Experiments to study the compression and unstable evolution of an isolated soap-film bubble containing helium, subjected to a strong planar shock wave (M=2.95) in ambient nitrogen, have been performed in a vertical shock tube of square internal cross section using planar laser diagnostics. The early phase of the interaction process is dominated by the formation of a primary vortex ring due to the baroclinic source of vorticity deposited during the shock-bubble interaction, and the mass transfer from the body of the bubble to the vortex ring. The late time (long after shock interaction) study reveals the presence of a secondary baroclinic source of vorticity at high Mach number which is responsible for the formation of counterrotating secondary and tertiary vortex rings and the subsequent larger rate of elongation of the bubble.

  15. Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

    NASA Technical Reports Server (NTRS)

    Kessel, R. L.; Armstrong, T. P.; Nuber, R.; Bandle, J.

    1985-01-01

    Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail.

  16. In-situ Raman spectroscopy and high-speed photography of a shocked triaminotrinitrobenzene based explosive

    SciTech Connect

    Saint-Amans, C.; Hébert, P. Doucet, M.; Resseguier, T. de

    2015-01-14

    We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamond anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.

  17. In-situ Raman spectroscopy and high-speed photography of a shocked triaminotrinitrobenzene based explosive

    NASA Astrophysics Data System (ADS)

    Saint-Amans, C.; Hébert, P.; Doucet, M.; de Resseguier, T.

    2015-01-01

    We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamond anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.

  18. Developing a platform for high-resolution phase contrast imaging of high pressure shock waves in matter

    NASA Astrophysics Data System (ADS)

    Schropp, Andreas; Patommel, Jens; Seiboth, Frank; Arnold, Brice; Galtier, Eric C.; Lee, Hae Ja; Nagler, Bob; Hastings, Jerome B.; Schroer, Christian G.

    2012-10-01

    Current and upcoming X-ray sources, such as the Linac Coherent Light Source (LCLS) at the Stanford Linear Accelerator Center (SLAC, USA), the SPring-8 Angstrom Compact Free Electron Laser (SACLA, Japan), or the X-ray Free Electron Laser (XFEL, Germany) will provide X-ray beams with outstanding properties.1, 2 Short and intense X-ray pulses of about 50 fs time duration and even shorter will push X-ray science to new frontiers such as, e. g., in high-resolution X-ray imaging, high-energy-density physics or in dynamical studies based on pump-probe techniques. Fast processes in matter often require high-resolution imaging capabilities either by magnified imaging in direct space or diffractive imaging in reciprocal space. In both cases highest resolutions require focusing the X-ray beam.3, 4 In order to further develop high-resolution imaging at free-electron laser sources we are planning a platform to carry out high-resolution phase contrast imaging experiments based on Beryllium compound refractive X-ray lenses (Be-CRLs) at the Matter in Extreme Conditions (MEC) endstation of the LCLS. The instrument provides all necessary equipment to induce high pressure shock waves by optical lasers. The propagation of a shock wave is then monitored with an X-ray Free Electron Laser (FEL) pulse by magnified phase contrast imaging. With the CRL optics, X-ray beam sizes in the sub-100nm range are expected, leading to a similar spatial resolution in the direct coherent projection image. The experiment combines different state-of-the art scientific techniques that are currently available at the LCLS. In this proceedings paper we describe the technical developments carried out at the LCLS in order to implement magnified X-ray phase contrast imaging at the MEC endstation.

  19. Relationships among Energy Price Shocks, Stock Market, and the Macroeconomy: Evidence from China

    PubMed Central

    Cong, Rong-Gang; Shen, Shaochuan

    2013-01-01

    This paper investigates the interactive relationships among China energy price shocks, stock market, and the macroeconomy using multivariate vector autoregression. The results indicate that there is a long cointegration among them. A 1% rise in the energy price index can depress the stock market index by 0.54% and the industrial value-adding growth by 0.037%. Energy price shocks also cause inflation and have a 5-month lag effect on stock market, which may result in the stock market “underreacting.” The energy price can explain stock market fluctuations better than the interest rate over a longer time period. Consequently, investors should pay greater attention to the long-term effect of energy on the stock market. PMID:23690737

  20. Relationships among energy price shocks, stock market, and the macroeconomy: evidence from China.

    PubMed

    Cong, Rong-Gang; Shen, Shaochuan

    2013-01-01

    This paper investigates the interactive relationships among China energy price shocks, stock market, and the macroeconomy using multivariate vector autoregression. The results indicate that there is a long cointegration among them. A 1% rise in the energy price index can depress the stock market index by 0.54% and the industrial value-adding growth by 0.037%. Energy price shocks also cause inflation and have a 5-month lag effect on stock market, which may result in the stock market "underreacting." The energy price can explain stock market fluctuations better than the interest rate over a longer time period. Consequently, investors should pay greater attention to the long-term effect of energy on the stock market. PMID:23690737

  1. High-Pressure Minerals in Meteorites: Constraints on Shock Conditions and Duration

    NASA Technical Reports Server (NTRS)

    Sharp, Thomas G.

    2004-01-01

    The objective of this research was to better understand the conditions and duration of shock metamorphism in meteorites through microstructural and microanalytical characterization of high-pressure minerals. A) Continue to investigate the mineralogy and microstructures of melt-veins in a suite of chondritic samples ranging from shock grades S3 through S6 to determine how the mineral assemblages that crystallize at high-pressure and are related to shock grade. B) Investigate the chemical, mineralogical, and microstructural heterogeneities that occur across melt veins to interpret crystallization histories. C) Use static high-pressure experiments to simulate crystallization of melt veins for mineralogical and textural comparisons with the melt veins of naturally shocked samples. D) Characterize the compositions and defect microstructures of polycrystalline ringwoodite, wadsleyite, majorite, (Mg,Fe)Si03-ilmenite and (Mg,Fe)SiO3-perovskite in S6 samples to understand the mechanisms of phase transformations that occur during shock. These results will combined with kinetic data to constrain the time scales of kinetic processes. E) Investigate the transformations of metastable high-pressure minerals back to low- pressure forms to constrain post-shock temperatures and estimates of the peak shock pressure. Of these objectives, we have obtained publishable data on A, B and D. I am currently doing difficult high-pressure melting and quench experiments on an L chondrite known as Mbale. These experiments will provide additional constraints on the mineral assemblages that are produced during rapid quench of an L chondrite at pressures of 16 to 25 GPa. Results from published or nearly published research is presented below. Lists of theses, dissertations and publications are given below.

  2. Shock to the system: How catastrophic events and institutional relationships impact Japanese energy policymaking, resilience, and innovation

    NASA Astrophysics Data System (ADS)

    Sklarew, Jennifer F.

    External shocks do not always generate energy system transformation. This dissertation examines how government relationships with electric utilities and the public impact whether shocks catalyze energy system change. The study analyzes Japanese energy policymaking from the oil crises through the Fukushima nuclear disaster. Findings reveal that policymakers' cooperation with and clout over electric utilities and the public can enable shocks to transform energy systems. When electric utilities wield clout, public trust in and influence on the government determine the existing system's resilience and the potential for a new system to emerge. Understanding this effect informs energy policy design and innovation.

  3. Evidence for confinement of low-energy cosmic rays ahead of interplanetary shock waves.

    NASA Technical Reports Server (NTRS)

    Palmeira, R. A. R.; Allum, F. R.

    1973-01-01

    Short-lived (about 15 min), low-energy proton increases associated with the passage of interplanetary shock waves have been previously reported. In the present paper, we have examined in a fine time scale (about 1 min) the concurrent particle and magnetic field data, taken by detectors on Explorer 34, for four of these events. Our results further support the view that these impulsive events are due to confinement of the solar cosmic-ray particles in the region just ahead (about 1,000,000 km) of the advancing shock front.

  4. [Effects of cold-shock on tomato seedlings under high temperature stress].

    PubMed

    Li, Sheng-Li; Xia, Ya-Zhen; Liu, Jin; Shi, Xiao-Dan; Sun, Zhi-Qiang

    2014-10-01

    High temperature stress (HTS) is one of the major limiting factors that affect the quality of intensively cultured seedlings in protected facilitates during hot season. Increasing the cross adaptive response of plant induced by temperature stress is an effective way to improve plant stress resistance. In order to explore the alleviating effect of cold-shock intensity on tomato seedlings under HTS, tomato seedlings were subjected to cold-shock treatments every day with 5 °C, 10 °C, and 15 °C for 10 min, 20 min, and 30 min, respectively, in an artificial climate chamber. The effect of single appropriate cold-shock on the gene expression of small heat shock proteins LeHSP 23.8 and CaHSP18 was investigated. The results showed that hypocotyl elongation and plant height of tomato seedlings were restrained by cold-shock treatment before HTS was met. The alleviating effect of tomato seedlings under HTS by cold-shock varied greatly with levels and durations of temperature. The membrane lipids in the leaf of tomato seedlings were subjected to peroxidation injury in the cold-shock treatment at 5 °C, in which the penetration of cell membrane was increased and the activities of antioxidant enzyme was inhibited. The alleviating effect to HTS by cold-shock was decreased with the increasing cold-shock duration at 10 °C, however, a reverse change was found at 15 °C. The results indicated that cross adaptive response of tomato seedling could be induced with a moderate cold-shock temperature for a proper duration before HTS was met. The optimum cold-shock treatment was at 10 °C for 10 min per day, under which, the dry mass, healthy index, activities of protective enzymes (including SOD, POD and CAT) in leaves of tomato seedlings were significantly increased, the contents of proline and soluble protein were enhanced, relative conductivity and malondialdehyde concentration were significantly decreased, and the expression levels of Le-HSP23.8 and CaHSP18 were increased compared

  5. Thermal Shock Properties of Yttria-Stabilized Zirconia Coatings Deposited Using Low-Energy Very Low Pressure Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Zhang, Nannan; Bolot, Rodolphe; Liao, Hanlin; Coddet, Christian

    2015-08-01

    Yttria-stabilized zirconia (YSZ) coatings have been frequently used as a thermal protective layer on the metal or alloy component surfaces. In the present study, ZrO2-7%Y2O3 thermal barrier coatings (TBCs) were successfully deposited by DC (direct current) plasma spray process under very low pressure conditions (less than 1 mbar) using low-energy plasma guns F4-VB and F100. The experiments were performed to evaluate the thermal shock resistance of different TBC specimens which were heated to 1373 K at a high-temperature cycling furnace and held for 0.5 h, followed by air cooling at room temperature for 0.2 h. For comparison, a corresponding atmospheric plasma spray (APS) counterpart was also elaborated to carry out the similar experiments. The results indicated that the very low pressure plasma spray (VLPPS) coatings displayed better thermal shock resistance. Moreover, the failure mechanism of the coatings was elucidated.

  6. Effect of High Shock Number on Acute Complication Development After Extracorporeal Shockwave Lithotripsy

    PubMed Central

    Hadj-Moussa, Miriam

    2013-01-01

    Abstract Purpose We assessed whether high shock number is associated with higher rates of acute complication development after extracorporeal shockwave lithotripsy (SWL). Patients and Methods A retrospective chart review of 372 patients who underwent 436 SWL procedures at 24 kV using a Medstone STS-T lithotripter (Medstone International Inc., Aliso Viejo, CA) was conducted. Complications occurred within 4 weeks of SWL. Treatments were split into three cohorts based on shock number (<2400, 2401–4000, and >4000). Postoperative sequelae of patients who were stone free and those with residual stone were studied separately. Chi-square tests were used to evaluate the relationship between shock number cohort and postoperative complication development. Results SWL treatments recorded for each cohort were 158 (37.4%), 145 (34.4%), and 119 (28.2%), respectively. The short-term complication rate when SWL was successful was 8.3% overall. Complication rate for each cohort was 9.5% (11), 7.8% (5), and 7.2% (7), respectively. When SWL was successful, statistical analysis revealed no significant difference between complication rates and shock number cohort (P=0.63). Complications in patients with a residual stone occurred after 41.4% of treatments and trended upward with shock number cohort, but did not reach statistical significance (P=0.84). Conclusions At high voltage, high shock number was not shown to cause higher rates of short-term postoperative complications, as experienced by patients, when SWL was successful or resulted in a residual stone, yet complication rates associated with residual stone burden were approximately five times as common. Forgoing a higher shock number in the presence of a residual stone may therefore increase the risks of sequelae immediately after SWL. PMID:23537270

  7. A High Order Finite Difference Scheme with Sharp Shock Resolution for the Euler Equations

    NASA Technical Reports Server (NTRS)

    Gerritsen, Margot; Olsson, Pelle

    1996-01-01

    We derive a high-order finite difference scheme for the Euler equations that satisfies a semi-discrete energy estimate, and present an efficient strategy for the treatment of discontinuities that leads to sharp shock resolution. The formulation of the semi-discrete energy estimate is based on a symmetrization of the Euler equations that preserves the homogeneity of the flux vector, a canonical splitting of the flux derivative vector, and the use of difference operators that satisfy a discrete analogue to the integration by parts procedure used in the continuous energy estimate. Around discontinuities or sharp gradients, refined grids are created on which the discrete equations are solved after adding a newly constructed artificial viscosity. The positioning of the sub-grids and computation of the viscosity are aided by a detection algorithm which is based on a multi-scale wavelet analysis of the pressure grid function. The wavelet theory provides easy to implement mathematical criteria to detect discontinuities, sharp gradients and spurious oscillations quickly and efficiently.

  8. Performance evaluation and parameter sensitivity of energy-harvesting shock absorbers on different vehicles

    NASA Astrophysics Data System (ADS)

    Guo, Sijing; Liu, Yilun; Xu, Lin; Guo, Xuexun; Zuo, Lei

    2016-07-01

    Traditional shock absorbers provide favourable ride comfort and road handling by dissipating the suspension vibration energy into heat waste. In order to harvest this dissipated energy and improve the vehicle fuel efficiency, many energy-harvesting shock absorbers (EHSAs) have been proposed in recent years. Among them, two types of EHSAs have attracted much attention. One is a traditional EHSA which converts the oscillatory vibration into bidirectional rotation using rack-pinion, ball-screw or other mechanisms. The other EHSA is equipped with a mechanical motion rectifier (MMR) that transforms the bidirectional vibration into unidirectional rotation. Hereinafter, they are referred to as NonMMR-EHSA and MMR-EHSA, respectively. This paper compares their performances with the corresponding traditional shock absorber by using closed-form analysis and numerical simulations on various types of vehicles, including passenger cars, buses and trucks. Results suggest that MMR-EHSA provides better ride performances than NonMMR-EHSA, and that MMR-EHSA is able to improve both the ride comfort and road handling simultaneously over the traditional shock absorber when installed on light-damped, heavy-duty vehicles. Additionally, the optimal parameters of MMR-EHSA are obtained for ride comfort. The optimal solutions ('Pareto-optimal solutions') are also obtained by considering the trade-off between ride comfort and road handling.

  9. Acoustical problems in high energy pulsed E-beams lasers

    NASA Technical Reports Server (NTRS)

    Horton, T. E.; Wylie, K. F.

    1976-01-01

    During the pulsing of high energy, CO2, electron beam lasers, a significant fraction of input energy ultimately appears as acoustical disturbances. The magnitudes of these disturbances were quantified by computer analysis. Acoustical and shock impedance data are presented on materials (Rayleigh type) which show promise in controlling acoustical disturbance in E-beam systems.

  10. A Study of Fundamental Shock Noise Mechanisms

    NASA Technical Reports Server (NTRS)

    Meadows, Kristine R.

    1997-01-01

    This paper investigates two mechanisms fundamental to sound generation in shocked flows: shock motion and shock deformation. Shock motion is modeled numerically by examining the interaction of a sound wave with a shock. This numerical approach is validated by comparison with results obtained by linear theory for a small-disturbance case. Analysis of the perturbation energy with Myers' energy corollary demonstrates that acoustic energy is generated by the interaction of acoustic disturbances with shocks. This analysis suggests that shock motion generates acoustic and entropy disturbance energy. Shock deformation is modeled numerically by examining the interaction of a vortex ring with a shock. These numerical simulations demonstrate the generation of both an acoustic wave and contact surfaces. The acoustic wave spreads cylindrically. The sound intensity is highly directional and the sound pressure increases with increasing shock strength. The numerically determined relationship between the sound pressure and the Mach number is found to be consistent with experimental observations of shock noise. This consistency implies that a dominant physical process in the generation of shock noise is modeled in this study.

  11. Recent development and future perspectives of low energy laser shock peening

    NASA Astrophysics Data System (ADS)

    Kalainathan, S.; Prabhakaran, S.

    2016-07-01

    The first part of the review involves the parameters controlling and optimization of low energy laser shock peening process. The second part presents the effect of laser peening without coating on ferrous, aluminum and titanium alloys. Therefore, the recently developed techniques and challenges on it are discussed. Opportunities to tackle the current challenges are overviewed. Finally, in the third part, the future perspectives of low energy laser peening on metal matrix composites and single crystals for several typical applications are deliberated.

  12. On the generation of magnetosheath high-speed jets by bow shock ripples

    PubMed Central

    Hietala, H; Plaschke, F

    2013-01-01

    [1]The terrestrial magnetosheath is embedded with coherent high-speed jets of about 1RE in scale, predominantly during quasi-radial interplanetary magnetic field (IMF). When these high dynamic pressure (Pdyn) jets hit the magnetopause, they cause large indentations and further magnetospheric effects. The source of these jets has remained controversial. One of the proposed mechanisms is based on ripples of the quasi-parallel bow shock. In this paper, we combine for the first time, 4 years of subsolar magnetosheath observations from the Time History of Events and Macroscale Interactions during Substorms mission and corresponding NASA/OMNI solar wind conditions with model calculations of a rippled bow shock. Concentrating on the magnetosheath close to the shock during intervals when the angle between the IMF and the Sun-Earth line was small, we find that (1) 97% of the observed jets can be produced by local ripples of the shock under the observed upstream conditions; (2) the coherent jets form a significant fraction of the high Pdyn tail of the magnetosheath flow distribution; (3) the magnetosheath Pdyn distribution matches the flow from a bow shock with ripples that have a dominant amplitude to wavelength ratio of about 9% (∼0.1RE/1RE) and are present ∼12% of the time at any given location. PMID:26167426

  13. On the generation of magnetosheath high speed jets by bow shock ripples (Invited)

    NASA Astrophysics Data System (ADS)

    Hietala, H.; Plaschke, F.

    2013-12-01

    The terrestrial magnetosheath is embedded with coherent high speed jets of about 1 RE in scale, predominantly during quasi-radial interplanetary magnetic field (IMF). When these high dynamic pressure (Pdyn) jets hit the magnetopause, they cause large indentations and further magnetospheric effects. The source of these jets has remained controversial. One of the proposed mechanisms is based on ripples of the quasi-parallel bow shock. In this paper, we combine for the first time four years of subsolar magnetosheath observations from the THEMIS mission and corresponding NASA/OMNI solar wind conditions with model calculations of a rippled bow shock. Concentrating on the magnetosheath close to the shock during low IMF cone-angles, we find that (1) 97% of the observed jets can be produced by local ripples of the shock under the observed upstream conditions; (2) the coherent jets form a significant fraction of the high Pdyn tail of the magnetosheath flow distribution; (3) the magnetosheath Pdyn distribution matches the flow from a bow shock with ripples that have a dominant amplitude to wavelength ratio of about 9% (~ 0.1 RE/1 RE) and are present ~12% of the time at any given location.

  14. Pyroxenes and olivines: Structural implications of shock-wave data for high pressure phases

    NASA Technical Reports Server (NTRS)

    Jeanloz, R.; Ahrens, T. J.

    1975-01-01

    The nature of the shock-induced, high-pressure phases of olivine and pyroxene rocks is examined in the light of data for the densities of a new class of perovskite-related silicate structures. Also examined are some new Hugoniot and release adiabat data for bronzite. Reexamining available shock data for magnesian pyroxenes and olivines leads to the conclusion that they define a mixed phase (or disequilibrium) region to about the 100 GPa range, related to the kinetics of phase transformation in these silicates. By recognizing this point, certain discrepancies in previous interpretations of shock data can be explained. A set of theoretical Hugonoits for pyroxene and olivine stoichiometry, perovskite-bearing assemblages was constructed based on their properties deduced from high-pressure work, showing that the shock data is compatible with transformations to perovskites in the 45-7GPa region. Finally, the shock data indicate very similar properties for olivine and pyroxene at high pressures making them both equally likely candidates for the lower mantle.

  15. Active Galactic Nuclei:. Sources for Ultra High Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Biermann, P. L.; Becker, J. K.; Caramete, L.; Gergely, L.; Mariş, I. C.; Meli, A.; de Souza, V.; Stanev, T.

    Ultra high energy cosmic ray events presently show a spectrum, which we interpret here as galactic cosmic rays due to a starburst, in the radio galaxy Cen A which is pushed up in energy by the shock of a relativistic jet. The knee feature and the particles with energy immediately higher in galactic cosmic rays then turn into the bulk of ultra high energy cosmic rays. This entails that all ultra high energy cosmic rays are heavy nuclei. This picture is viable if the majority of the observed ultra high energy events come from the radio galaxy Cen A, and are scattered by intergalactic magnetic fields across much of the sky.

  16. Occurrence of high-beta superthermal plasma events in the close environment of Jupiter's bow shock as observed by Ulysses

    SciTech Connect

    Marhavilas, P. K.; Sarris, E. T.; Anagnostopoulos, G. C.

    2011-01-04

    The ratio of the plasma pressure to the magnetic field pressure (or of their energy densities) which is known as the plasma parameter 'beta'({beta}) has important implications to the propagation of energetic particles and the interaction of the solar wind with planetary magnetospheres. Although in the scientific literature the contribution of the superthermal particles to the plasma pressure is generally assumed negligible, we deduced, by analyzing energetic particles and magnetic field measurements recorded by the Ulysses spacecraft, that in a series of events, the energy density contained in the superthermal tail of the particle distribution is comparable to or even higher than the energy density of the magnetic field, creating conditions of high-beta plasma. More explicitly, in this paper we analyze Ulysses/HI-SCALE measurements of the energy density ratio (parameter {beta}{sub ep}) of the energetic ions'(20 keV to {approx}5 MeV) to the magnetic field's in order to find occurrences of high-beta ({beta}{sub ep}>1) superthermal plasma conditions in the environment of the Jovian magnetosphere, which is an interesting plasma laboratory and an important source of emissions in our solar system. In particular, we examine high-beta ion events close to Jupiter's bow shock, which are produced by two processes: (a) bow shock ion acceleration and (b) ion leakage from the magnetosphere.

  17. Numerical dissipation control in high order shock-capturing schemes for LES of low speed flows

    NASA Astrophysics Data System (ADS)

    Kotov, D. V.; Yee, H. C.; Wray, A. A.; Sjögreen, B.; Kritsuk, A. G.

    2016-02-01

    The Yee & Sjögreen adaptive numerical dissipation control in high order scheme (High Order Filter Methods for Wide Range of Compressible Flow Speeds, ICOSAHOM 09, 2009) is further improved for DNS and LES of shock-free turbulence and low speed turbulence with shocklets. There are vastly different requirements in the minimization of numerical dissipation for accurate turbulence simulations of different compressible flow types and flow speeds. Traditionally, the method of choice for shock-free turbulence and low speed turbulence are by spectral, high order central or high order compact schemes with high order linear filters. With a proper control of a local flow sensor, appropriate amount of numerical dissipation in high order shock-capturing schemes can have spectral-like accuracy for compressible low speed turbulent flows. The development of the method includes an adaptive flow sensor with automatic selection on the amount of numerical dissipation needed at each flow location for more accurate DNS and LES simulations with less tuning of parameters for flows with a wide range of flow speed regime during the time-accurate evolution, e.g., time varying random forcing. An automatic selection of the different flow sensors catered to the different flow types is constructed. A Mach curve and high-frequency oscillation indicators are used to reduce the tuning of parameters in controlling the amount of shock-capturing numerical dissipation to be employed for shock-free turbulence, low speed turbulence and turbulence with strong shocks. In Kotov et al. (High Order Numerical Methods for LES of Turbulent Flows with Shocks, ICCFD8, Chengdu, Sichuan, China, July 14-18, 2014) the LES of a turbulent flow with a strong shock by the Yee & Sjögreen scheme indicated a good agreement with the filtered DNS data. A work in progress for the application of the adaptive flow sensor for compressible turbulence with time-varying random forcing is forthcoming. The present study examines the

  18. Blast Shock Wave Mitigation Using the Hydraulic Energy Redirection and Release Technology

    PubMed Central

    Chen, Yun; Huang, Wei; Constantini, Shlomi

    2012-01-01

    A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel. PMID:22745740

  19. Blast shock wave mitigation using the hydraulic energy redirection and release technology.

    PubMed

    Chen, Yun; Huang, Wei; Constantini, Shlomi

    2012-01-01

    A hydraulic energy redirection and release technology has been developed for mitigating the effects of blast shock waves on protected objects. The technology employs a liquid-filled plastic tubing as a blast overpressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy in the plastic tubings. The hydraulic energy is redirected through the plastic tubings to the openings at the lower ends, and then is quickly released with the liquid flowing out through the openings. The samples of the specifically designed body armor in which the liquid-filled plastic tubings were installed vertically as the outer layer of the body armor were tested. The blast test results demonstrated that blast overpressure behind the body armor samples was remarkably reduced by 97% in 0.2 msec after the liquid flowed out of its appropriate volume through the openings. The results also suggested that a volumetric liquid surge might be created when kinetic energy of blast shock wave was transferred into hydraulic energy to cause a rapid physical movement or displacement of the liquid. The volumetric liquid surge has a strong destructive power, and can cause a noncontact, remote injury in humans (such as blast-induced traumatic brain injury and post-traumatic stress disorder) if it is created in cardiovascular system. The hydraulic energy redirection and release technology can successfully mitigate blast shock waves from the outer surface of the body armor. It should be further explored as an innovative approach to effectively protect against blast threats to civilian and military personnel. PMID:22745740

  20. Robust and Accurate Shock Capturing Method for High-Order Discontinuous Galerkin Methods

    NASA Technical Reports Server (NTRS)

    Atkins, Harold L.; Pampell, Alyssa

    2011-01-01

    A simple yet robust and accurate approach for capturing shock waves using a high-order discontinuous Galerkin (DG) method is presented. The method uses the physical viscous terms of the Navier-Stokes equations as suggested by others; however, the proposed formulation of the numerical viscosity is continuous and compact by construction, and does not require the solution of an auxiliary diffusion equation. This work also presents two analyses that guided the formulation of the numerical viscosity and certain aspects of the DG implementation. A local eigenvalue analysis of the DG discretization applied to a shock containing element is used to evaluate the robustness of several Riemann flux functions, and to evaluate algorithm choices that exist within the underlying DG discretization. A second analysis examines exact solutions to the DG discretization in a shock containing element, and identifies a "model" instability that will inevitably arise when solving the Euler equations using the DG method. This analysis identifies the minimum viscosity required for stability. The shock capturing method is demonstrated for high-speed flow over an inviscid cylinder and for an unsteady disturbance in a hypersonic boundary layer. Numerical tests are presented that evaluate several aspects of the shock detection terms. The sensitivity of the results to model parameters is examined with grid and order refinement studies.

  1. HSF1 drives a transcriptional program distinct from heat shock to support highly malignant human cancers

    PubMed Central

    Mendillo, Marc L.; Santagata, Sandro; Koeva, Martina; Bell, George W.; Hu, Rong; Tamimi, Rulla M.; Fraenkel, Ernest; Ince, Tan A.; Whitesell, Luke; Lindquist, Susan

    2012-01-01

    SUMMARY Heat-Shock Factor 1 (HSF1), master regulator of the heat-shock response, facilitates malignant transformation, cancer cell survival and proliferation in model systems. The common assumption is that these effects are mediated through regulation of heat-shock protein (HSP) expression. However, the transcriptional network that HSF1 coordinates directly in malignancy and its relationship to the heat-shock response have never been defined. By comparing cells with high and low malignant potential alongside their non-transformed counterparts, we identify an HSF1-regulated transcriptional program specific to highly malignant cells and distinct from heat shock. Cancer-specific genes in this program support oncogenic processes: cell-cycle regulation, signaling, metabolism, adhesion and translation. HSP genes are integral to this program, however, many are uniquely regulated in malignancy. This HSF1 cancer program is active in breast, colon and lung tumors isolated directly from human patients and is strongly associated with metastasis and death. Thus, HSF1 rewires the transcriptome in tumorigenesis, with prognostic and therapeutic implications. PMID:22863008

  2. A technique for in-target digital recording during high shock events

    NASA Astrophysics Data System (ADS)

    Menna, Thomas L.; Swann, Jeffrey D.

    An innovative data acquisition technique is described that allows a variety of long duration measurements created from high shock events such as an explosive blast while significantly reducing the risk of data degradation or loss. This technique employs an electronics system that is incorporated into an instrumentation package. The instrumentation package consists of a state-of-the-art high shock resistant analog-to-digital recorder, sensors, battery pack, and signal and trigger conditioning and monitoring circuits. These components are shock isolated and encased in either a protective canister or placed in a hardened recoverable component of the target. Active remote monitoring of this system provides system status information that is necessary for tests utilizing expensive large scale targets that are not accessible for days or weeks before the test.

  3. Energy Characteristics of Electric Drive of Oscillatory Motion at the Shock-Free Start

    NASA Astrophysics Data System (ADS)

    Payuk, L. A.; Voronina, N. A.; Galtseva, O. V.

    2016-01-01

    The peculiarity of operation of oscillatory electric drive with doubly-fed motor at realization of algorithm of shock-free start was considered. The method of evaluating of energy parameters of such motors operating at the resonance mode with yueTOM of quantitative and qualitative components of the process of energy conversion by an electric motor (doubly-fed motor) is proposed. The calculation of energy characteristics of electric drive of this type was made, the results of calculation show an increase of energy efficiency (an average, generalized efficiency coefficient nE increased by 10%), which confirms the practical significance of the research object.

  4. Shock-to-detonation transition of RDX and NTO based composite high explosives: experiments and modeling

    NASA Astrophysics Data System (ADS)

    Baudin, Gerard; Roudot, Marie; Genetier, Marc

    2013-06-01

    Composite HMX and NTO based high explosives (HE) are widely used in ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside HE. Comparing to a pressed HE, a composite HE is not porous and the hot-spots are mainly located at the grain - binder interface leading to a different behavior during shock-to-detonation transition. An investigation of how shock-to-detonation transition occurs inside composite HE containing RDX and NTO is proposed in this lecture. Two composite HE have been studied. The first one is HMX - HTPB 82:18. The second one is HMX - NTO - HTPB 12:72:16. These HE have been submitted to plane sustained shock waves at different pressure levels using a laboratory powder gun. Pressure signals are measured using manganin gauges inserted at several distances inside HE. The corresponding run-distances to detonation are determined using wedge test experiments where the plate impact is performed using a powder gun. Both HE exhibit a single detonation buildup curve in the distance - time diagram of shock-to-detonation transition. This feature seems a common shock-to-detonation behavior for composite HE without porosity. This behavior is also confirmed for a RDX - HTPB 85:15 based composite HE. Such a behavior is exploited to determine the heterogeneous reaction rate versus the shock pressure using a method based on the Cauchy-Riemann problem inversion. The reaction rate laws obtained allow to compute both run-distance to detonation and pressure signals.

  5. Low Energy Shock Wave Therapy Induces Angiogenesis in Acute Hind-Limb Ischemia via VEGF Receptor 2 Phosphorylation

    PubMed Central

    Holfeld, Johannes; Tepeköylü, Can; Blunder, Stefan; Lobenwein, Daniela; Kirchmair, Elke; Dietl, Marion; Kozaryn, Radoslaw; Lener, Daniela; Theurl, Markus; Paulus, Patrick; Kirchmair, Rudolf; Grimm, Michael

    2014-01-01

    Objectives Low energy shock waves have been shown to induce angiogenesis, improve left ventricular ejection fraction and decrease angina symptoms in patients suffering from chronic ischemic heart disease. Whether there is as well an effect in acute ischemia was not yet investigated. Methods Hind-limb ischemia was induced in 10–12 weeks old male C57/Bl6 wild-type mice by excision of the left femoral artery. Animals were randomly divided in a treatment group (SWT, 300 shock waves at 0.1 mJ/mm2, 5 Hz) and untreated controls (CTR), n = 10 per group. The treatment group received shock wave therapy immediately after surgery. Results Higher gene expression and protein levels of angiogenic factors VEGF-A and PlGF, as well as their receptors Flt-1 and KDR have been found. This resulted in significantly more vessels per high-power field in SWT compared to controls. Improvement of blood perfusion in treatment animals was confirmed by laser Doppler perfusion imaging. Receptor tyrosine kinase profiler revealed significant phosphorylation of VEGF receptor 2 as an underlying mechanism of action. The effect of VEGF signaling was abolished upon incubation with a VEGFR2 inhibitor indicating that the effect is indeed VEGFR 2 dependent. Conclusions Low energy shock wave treatment induces angiogenesis in acute ischemia via VEGF receptor 2 stimulation and shows the same promising effects as known from chronic myocardial ischemia. It may therefore develop as an adjunct to the treatment armentarium of acute muscle ischemia in limbs and myocardium. PMID:25093816

  6. 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.

  7. High-energy detector

    DOEpatents

    Bolotnikov, Aleksey E.; Camarda, Giuseppe; Cui, Yonggang; James, Ralph B.

    2011-11-22

    The preferred embodiments are directed to a high-energy detector that is electrically shielded using an anode, a cathode, and a conducting shield to substantially reduce or eliminate electrically unshielded area. The anode and the cathode are disposed at opposite ends of the detector and the conducting shield substantially surrounds at least a portion of the longitudinal surface of the detector. The conducting shield extends longitudinally to the anode end of the detector and substantially surrounds at least a portion of the detector. Signals read from one or more of the anode, cathode, and conducting shield can be used to determine the number of electrons that are liberated as a result of high-energy particles impinge on the detector. A correction technique can be implemented to correct for liberated electron that become trapped to improve the energy resolution of the high-energy detectors disclosed herein.

  8. A Class of High-Resolution Explicit and Implicit Shock-Capturing Methods

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1994-01-01

    The development of shock-capturing finite difference methods for hyperbolic conservation laws has been a rapidly growing area for the last decade. Many of the fundamental concepts, state-of-the-art developments and applications to fluid dynamics problems can only be found in meeting proceedings, scientific journals and internal reports. This paper attempts to give a unified and generalized formulation of a class of high-resolution, explicit and implicit shock capturing methods, and to illustrate their versatility in various steady and unsteady complex shock waves, perfect gases, equilibrium real gases and nonequilibrium flow computations. These numerical methods are formulated for the purpose of ease and efficient implementation into a practical computer code. The various constructions of high-resolution shock-capturing methods fall nicely into the present framework and a computer code can be implemented with the various methods as separate modules. Included is a systematic overview of the basic design principle of the various related numerical methods. Special emphasis will be on the construction of the basic nonlinear, spatially second and third-order schemes for nonlinear scalar hyperbolic conservation laws and the methods of extending these nonlinear scalar schemes to nonlinear systems via the approximate Riemann solvers and flux-vector splitting approaches. Generalization of these methods to efficiently include real gases and large systems of nonequilibrium flows will be discussed. Some perbolic conservation laws to problems containing stiff source terms and terms and shock waves are also included. The performance of some of these schemes is illustrated by numerical examples for one-, two- and three-dimensional gas-dynamics problems. The use of the Lax-Friedrichs numerical flux to obtain high-resolution shock-capturing schemes is generalized. This method can be extended to nonlinear systems of equations without the use of Riemann solvers or flux

  9. Laser-induced shock wave lithotripsy. Influence of laser pulse energy and irrigation solutions on stone disintegration.

    PubMed

    Hofmann, R; Hartung, R; Schmidt-Kloiber, H; Reichel, E

    1990-01-01

    With a high intensity Q-switched Nd-YAG laser shock waves can be generated in a liquid close to the calculus. Up to 80 mJ single pulse energy with 8 nsec pulse duration can be transmitted through flexible quartz fibers. Energy conversion and enhancement can be accomplished at the fiber tip with optical focussing of the light at the quartz tip, with irrigation solutions and with high pulse energies. Iron-III-dextran solutions (1 mg Fe3+/1) and magnesium chloride (50 mmol/l) increased the pressure in the laser induced breakdown up to ten times (8,000-10,000 bar). Smaller stone particles and higher efficacy in stone fragmentation could be achieved. PMID:1969188

  10. High-Order Shock-Capturing Methods for Modeling Dynamics of the Solar Atmosphere

    NASA Technical Reports Server (NTRS)

    Bryson, Steve; Kosovichev, Alexander; Levy, Doron

    2004-01-01

    We use one-dimensional high-order central shock capturing numerical methods to study the response of various model solar atmospheres to forcing at the solar surface. The dynamics of the atmosphere is modeled with the Euler equations in a variable-sized flux tube in the presence of gravity. We study dynamics of the atmosphere suggestive of spicule formation and coronal oscillations. These studies are performed on observationally-derived model atmospheres above the quiet sun and above sunspots. To perform these simulations, we provide a new extension of existing second- and third- order shock-capturing methods to irregular grids. We also solve the problem of numerically maintaining initial hydrostatic balance via the introduction of new variables in the model equations and a careful initialization mechanism. We find several striking results: all model atmospheres respond to a single impulsive perturbation with several strong shock waves consistent with the rebound-shock model. These shock waves lift material and the transition region well into the initial corona, and the sensitivity of this lift to the initial impulse depends non-linearly on the details of the atmosphere model. We also reproduce an observed 3-minute coronal oscillation above sunspots compared to 5-minute oscillations above the quiet sun.

  11. Controlled tissue emulsification produced by high intensity focused ultrasound shock waves and millisecond boiling

    PubMed Central

    Khokhlova, Tatiana D.; Canney, Michael S.; Khokhlova, Vera A.; Sapozhnikov, Oleg A.; Crum, Lawrence A.; Bailey, Michael R.

    2011-01-01

    In high intensity focused ultrasound (HIFU) applications, tissue may be thermally necrosed by heating, emulsified by cavitation, or, as was recently discovered, emulsified using repetitive millisecond boiling caused by shock wave heating. Here, this last approach was further investigated. Experiments were performed in transparent gels and ex vivo bovine heart tissue using 1, 2, and 3 MHz focused transducers and different pulsing schemes in which the pressure, duty factor, and pulse duration were varied. A previously developed derating procedure to determine in situ shock amplitudes and the time-to-boil was refined. Treatments were monitored using B-mode ultrasound. Both inertial cavitation and boiling were observed during exposures, but emulsification occurred only when shocks and boiling were present. Emulsified lesions without thermal denaturation were produced with shock amplitudes sufficient to induce boiling in less than 20 ms, duty factors of less than 0.02, and pulse lengths shorter than 30 ms. Higher duty factors or longer pulses produced varying degrees of thermal denaturation combined with mechanical emulsification. Larger lesions were obtained using lower ultrasound frequencies. The results show that shock wave heating and millisecond boiling is an effective and reliable way to emulsify tissue while monitoring the treatment with ultrasound. PMID:22088025

  12. Controlled tissue emulsification produced by high intensity focused ultrasound shock waves and millisecond boiling.

    PubMed

    Khokhlova, Tatiana D; Canney, Michael S; Khokhlova, Vera A; Sapozhnikov, Oleg A; Crum, Lawrence A; Bailey, Michael R

    2011-11-01

    In high intensity focused ultrasound (HIFU) applications, tissue may be thermally necrosed by heating, emulsified by cavitation, or, as was recently discovered, emulsified using repetitive millisecond boiling caused by shock wave heating. Here, this last approach was further investigated. Experiments were performed in transparent gels and ex vivo bovine heart tissue using 1, 2, and 3 MHz focused transducers and different pulsing schemes in which the pressure, duty factor, and pulse duration were varied. A previously developed derating procedure to determine in situ shock amplitudes and the time-to-boil was refined. Treatments were monitored using B-mode ultrasound. Both inertial cavitation and boiling were observed during exposures, but emulsification occurred only when shocks and boiling were present. Emulsified lesions without thermal denaturation were produced with shock amplitudes sufficient to induce boiling in less than 20 ms, duty factors of less than 0.02, and pulse lengths shorter than 30 ms. Higher duty factors or longer pulses produced varying degrees of thermal denaturation combined with mechanical emulsification. Larger lesions were obtained using lower ultrasound frequencies. The results show that shock wave heating and millisecond boiling is an effective and reliable way to emulsify tissue while monitoring the treatment with ultrasound. PMID:22088025

  13. Observation of water-shock-wave propagation emanated from the roughened optical fiber end surface by the pulse laser energy input

    NASA Astrophysics Data System (ADS)

    Nakahara, Motonao; Nagayama, Kunihito

    1999-06-01

    Pressure enhancement of the generated shock waves in water has been found, when pulse laser energy is transmitted through an optical fiber whose end surface is intentionally roughened. More effective high-pressure shock generation can be possible by the aluminum coating on the roughened fiber surface. In case of the moderate laser energy of about 50 mJ input to the fiber, it is found that the phenomena are dependent on (1) the roughness, (2) the fiber diameter, and (3) the ambient medium. Shock wave generation can be detected successively by the laser input, but found to degrade down. Cavitation bubbles have also been observed after each shot. When the fiber end is in air, an intense and long-stretched flash can be observed. We have observed the phenomena by the pulse laser shadowgraphy.

  14. High G pyrotechnic shock simulation using metal-to-metal impact

    NASA Technical Reports Server (NTRS)

    Bai, M.; Thatcher, W.

    1979-01-01

    A technique for simulating high g level pyrotechnic shocks is described and the results of applying the technique to obtain the MIL-STD-1540A shock spectrum with a maximum acceleration of 18,000g at 2,000 Hz are presented. Designing the resonant beam and plate on which the test unit is mounted, and generating a proper impulsive load on them, were the essentials of the technique. One dimensional stress wave and Euler equations were employed in the design. A metal pendulum hammer was used to generate the impulsive load.

  15. Effect of high dose corticosteroids alone or combined with other drugs on survival in septic shock.

    PubMed

    Almqvist, P M; Ekström, B; Kuenzig, M; Haglund, U; Schwartz, S I

    1985-01-01

    The effect of high dose corticosteroids on survival has been studied in a limited number of canine septic shock models which are reviewed in this presentation. Following injection of live bacteria neither methylprednisolone, nor gentamicin but a combination improved survival. Methylprednisolone increased survival following a slow but not a bolus infusion of endotoxin. In a recent study the effects of short term treatment with methylprednisolone, naloxone and ibuprofen were studied in endotoxin shock. All control animals died within 36 hours. Five of 9 dogs receiving the combination methylprednisolone, naloxone and ibuprofen were permanent survivors. The combined treatment with methylprednisolone and ibuprofen also increased survival. Dogs treated with methylprednisolone alone did not differ significantly from controls. It is concluded that methylprednisolone alone has no significant effect on survival in septic shock, but seems to be an important therapeutic factor to achieve increased survival. PMID:3867205

  16. Shock focusing flow field simulated by a high-resolution numerical algorithm

    NASA Astrophysics Data System (ADS)

    Jung, Y. G.; Chang, K. S.

    2012-11-01

    Shock-focusing concave reflector is a very simple and effective tool to obtain a high-pressure pulse wave near the physical focal point. In the past, many optical images were obtained through experimental studies. However, measurement of field variables is not easy because the phenomenon is of short duration and the magnitude of shock waves is varied from pulse to pulse due to poor reproducibility. Using a wave propagation algorithm and the Cartesian embedded boundary method, we have successfully obtained numerical schlieren images that resemble the experimental results. By the numerical results, various field variables, such as pressure, density and vorticity, become available for the better understanding and design of shock focusing devices.

  17. Influence of High- G Mechanical Shock and Thermal Cycling on Localized Recrystallization in Sn-Ag-Cu Solder Interconnects

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Kyu; Kim, Choong-Un; Bieler, Thomas R.

    2014-01-01

    The impact of isothermal aging and recrystallized grain structure distribution on mechanical shock and thermal cycling performance of solder joints with 1% and 3% silver content Sn-Ag-Cu interconnects were investigated. Localized recrystallized grain structure distributions were analyzed to identify correlations between the microstructure evolution and shock performance. The results reveal that the shock tolerance depends on the amount of shock energy that can be absorbed during each shock cycle, which depends on microstructural features. Based on the recrystallized grain distribution, additional isothermal aging in 1% silver Sn-Ag-Cu interconnects shows improved shock performance, whereas degraded shock performance was observed in 3% Sn-Ag-Cu interconnects. Using the same grain boundary distribution analysis on thermally cycled samples, relationships between the particle size distribution, localized recrystallized grain structure development, shock, and thermomechanical performance were identified: finer particle spacing is beneficial for thermal cycling as it resists grain boundary generation, while conversely, wider particle spacing facilitates recrystallization and grain boundary mobility that allows Sn to absorb shock energy.

  18. High energy-density science on the National Ignition Facility

    SciTech Connect

    Campbell, E.M.; Cauble, R.; Remington, B.A.

    1997-08-01

    The National Ignition Facility, as well as its French counterpart Le Laser Megajoule, have been designed to confront one of the most difficult and compelling problem in shock physics - the creation of a hot, compassed DT plasma surrounded and confined by cold, nearly degenerate DT fuel. At the same time, these laser facilities will present the shock physics community with unique tools for the study of high energy density matter at states unreachable by any other laboratory technique. Here we describe how these lasers can contribute to investigations of high energy density in the area of material properties and equations of state, extend present laboratory shock techniques such as high-speed jets to new regimes, and allow study of extreme conditions found in astrophysical phenomena.

  19. Tensile-strength apparatus applies high strain-rate loading with minimum shock

    NASA Technical Reports Server (NTRS)

    Cotrill, H. E., Jr.; Mac Glashan, W. F., Jr.

    1966-01-01

    Tensile-strength testing apparatus employs a capillary bundle through which a noncompressible fluid is extruded and a quick-release valve system. This apparatus applies the test loads at relatively constant very high strain rates with minimal shock and vibration to the tensile specimen and apparatus.

  20. High energy beam lines

    NASA Astrophysics Data System (ADS)

    Marchetto, M.; Laxdal, R. E.

    2014-01-01

    The ISAC post accelerator comprises an RFQ, DTL and SC-linac. The high energy beam lines connect the linear accelerators as well as deliver the accelerated beams to two different experimental areas. The medium energy beam transport (MEBT) line connects the RFQ to the DTL. The high energy beam transport (HEBT) line connects the DTL to the ISAC-I experimental stations (DRAGON, TUDA-I, GPS). The DTL to superconducting beam (DSB) transport line connects the ISAC-I and ISAC-II linacs. The superconducting energy beam transport (SEBT) line connects the SC linac to the ISAC-II experimental station (TUDA-II, HERACLES, TIGRESS, EMMA and GPS). All these lines have the function of transporting and matching the beams to the downstream sections by manipulating the transverse and longitudinal phase space. They also contain diagnostic devices to measure the beam properties.

  1. Generation of ultra-high-pressure shocks by collision of a fast plasma projectile driven in the laser-induced cavity pressure acceleration scheme with a solid target

    SciTech Connect

    Badziak, J.; Rosiński, M.; Krousky, E.; Kucharik, M.; Liska, R.; Ullschmied, J.

    2015-03-15

    A novel, efficient method of generating ultra-high-pressure shocks is proposed and investigated. In this method, the shock is generated by collision of a fast plasma projectile (a macro-particle) driven by laser-induced cavity pressure acceleration (LICPA) with a solid target placed at the LICPA accelerator channel exit. Using the measurements performed at the kilojoule PALS laser facility and two-dimensional hydrodynamic simulations, it is shown that the shock pressure ∼ Gbar can be produced with this method at the laser driver energy of only a few hundred joules, by an order of magnitude lower than the energy needed for production of such pressure with other laser-based methods known so far.

  2. Generation of ultra-high-pressure shocks by collision of a fast plasma projectile driven in the laser-induced cavity pressure acceleration scheme with a solid target

    NASA Astrophysics Data System (ADS)

    Badziak, J.; Rosiński, M.; Krousky, E.; Kucharik, M.; Liska, R.; Ullschmied, J.

    2015-03-01

    A novel, efficient method of generating ultra-high-pressure shocks is proposed and investigated. In this method, the shock is generated by collision of a fast plasma projectile (a macro-particle) driven by laser-induced cavity pressure acceleration (LICPA) with a solid target placed at the LICPA accelerator channel exit. Using the measurements performed at the kilojoule PALS laser facility and two-dimensional hydrodynamic simulations, it is shown that the shock pressure ˜ Gbar can be produced with this method at the laser driver energy of only a few hundred joules, by an order of magnitude lower than the energy needed for production of such pressure with other laser-based methods known so far.

  3. Shock compression response of highly reactive Ni + Al multilayered thin foils

    NASA Astrophysics Data System (ADS)

    Kelly, Sean C.; Thadhani, Naresh N.

    2016-03-01

    The shock-compression response of Ni + Al multilayered thin foils is investigated using laser-accelerated thin-foil plate-impact experiments over the pressure range of 2 to 11 GPa. The foils contain alternating Ni and Al layers (parallel but not flat) of nominally 50 nm bilayer spacing. The goal is to determine the equation of state and shock-induced reactivity of these highly reactive fully dense thin-foil materials. The laser-accelerated thin-foil impact set-up involved combined use of photon-doppler-velocimetry to monitor the acceleration and impact velocity of an aluminum flyer, and VISAR interferometry was used to monitor the back free-surface velocity of the impacted Ni + Al multilayered target. The shock-compression response of the Ni + Al target foils was determined using experimentally measured parameters and impedance matching approach, with error bars identified considering systematic and experimental errors. Meso-scale CTH shock simulations were performed using real imported microstructures of the cross-sections of the multilayered Ni + Al foils to compute the Hugoniot response (assuming no reaction) for correlation with their experimentally determined equation of state. It was observed that at particle velocities below ˜150 m/s, the experimentally determined equation of state trend matches the CTH-predicted inert response and is consistent with the observed unreacted state of the recovered Ni + Al target foils from this velocity regime. At higher particle velocities, the experimentally determined equation of state deviates from the CTH-predicted inert response. A complete and self-sustained reaction is also seen in targets recovered from experiments performed at these higher particle velocities. The deviation in the measured equation of state, to higher shock speeds and expanded volumes, combined with the observation of complete reaction in the recovered multilayered foils, confirmed via microstructure characterization, is indicative of the occurrence

  4. Finite element modeling of acoustic wave propagation and energy deposition in bone during extracorporeal shock wave treatment

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofeng; Matula, Thomas J.; Ma, Yong; Liu, Zheng; Tu, Juan; Guo, Xiasheng; Zhang, Dong

    2013-06-01

    It is well known that extracorporeal shock wave treatment is capable of providing a non-surgical and relatively pain free alternative treatment modality for patients suffering from musculoskeletal disorders but do not respond well to conservative treatments. The major objective of current work is to investigate how the shock wave (SW) field would change if a bony structure exists in the path of the acoustic wave. Here, a model of finite element method (FEM) was developed based on linear elasticity and acoustic propagation equations to examine SW propagation and deflection near a mimic musculoskeletal bone. High-speed photography experiments were performed to record cavitation bubbles generated in SW field with the presence of mimic bone. By comparing experimental and simulated results, the effectiveness of FEM model could be verified and strain energy distributions in the bone were also predicted according to numerical simulations. The results show that (1) the SW field will be deflected with the presence of bony structure and varying deflection angles can be observed as the bone shifted up in the z-direction relative to SW geometric focus (F2 focus); (2) SW deflection angels predicted by the FEM model agree well with experimental results obtained from high-speed photographs; and (3) temporal evolutions of strain energy distribution in the bone can also be evaluated based on FEM model, with varied vertical distance between F2 focus and intended target point on the bone surface. The present studies indicate that, by combining MRI/CT scans and FEM modeling work, it is possible to better understand SW propagation characteristics and energy deposition in musculoskeletal structure during extracorporeal shock wave treatment, which is important for standardizing the treatment dosage, optimizing treatment protocols, and even providing patient-specific treatment guidance in clinic.

  5. On the importance of commodity and energy price shocks for the macroeconomy

    NASA Astrophysics Data System (ADS)

    Edelstein, Paul S.

    Although higher commodity prices are commonly thought to presage higher rates of inflation, the existing literature suggests that the predictive power of commodity prices for inflation has waned since the 1980s. In the first chapter, I show that this result can be overturned using state-of-the-art forecast combination methods. Moreover, commodity prices are shown to contain predictive information not contained in the leading principal components of a broad set of macroeconomic and financial variables. These improved inflation forecasts are of little value, however, for predicting actual Fed policy decisions. The remaining two chapters study the effect of energy price shocks on U.S. consumer and business expenditures. In the second chapter, I show that there is no statistical support for the presence of asymmetries in the response of real consumption to energy price increases and decreases. This finding has important implications for empirical and theoretical models of the transmission of energy price shocks. I then quantify the direct effect on real consumption of (1) unanticipated changes in discretionary income, (2) shifts in precautionary savings, and (3) changes in the operating cost of energy-using durables. Finally, I trace the declining importance of energy price shocks relative to the 1970s to changes in the composition of U.S. automobile production and the declining overall importance of the U.S. automobile sector. An alternative source of asymmetry is the response of nonresidential fixed investment to energy price shocks. In the third chapter, I show that the apparent asymmetry in the estimated responses of business fixed investment in equipment and structures is largely an artifact (1) of the aggregation of mining-related expenditures by the oil, natural gas, and coal mining industry and all other expenditures, and (2) of ignoring an exogenous shift in investment caused by the 1986 Tax Reform Act. Once symmetry is imposed and miningrelated expenditures

  6. Low-energy particles at the bow shock, magnetopause, and outer magnetosphere of Saturn

    SciTech Connect

    Maclennan, C.G.; Lanzerotti, L.J.; Krimigis, S.M.; Lepping, R.P.

    1983-11-01

    Low-energy electron (>22 keV) and protons (> or approx. =30 keV) measured by the Low-Energy Charged Particle Experiment (LECP) during the encounters of the two Voyager spacecraft with Saturn are described. The characteristics of the dayside bow shock, magnetopause, and outer magnetosphere are emphasized. Only one crossing of the Saturian bow shock was observed inbound during the Voyager 1 encounter, whereas five crossings of the bow shock were identified during the Voyager 2 approach to the planet. During several of these bow shock crossings, low energy protons were observed to be streaming from the direction of the dawnside of the magnetosphere. In the magnetosheath the protons were observed to be oriented primarily with pitch angles of approx.90/sup 0/. Prior to the inbound magnetopause crossings (as defined by the magnetometer experiment on Voyager), the low-energy protons and electrons were observed to increase in intensity. Further, during Voyager 2 encounter, an increase in the proton and electron fluxes accompanied a change in orientation of the magnetosheath magnetioc field from one with a vertical component opposite to the planetary field to one with a vertical component in the direction of the planetary field. Examination of the flux distributions of the protons suggests that the magnetopuase was moving inward with a lower limit speed of approx.10 km/s during the Voyager 2 approach to the planet. The observed average subsolar magnetopause position at the time of Voyager 2 encounter was 18.5 R/sub S/, whereas during the Voyager 1 encounter it was considerably more extended, at 23.5 R/sub S/.

  7. Statistical simulation of internal energy exchange in shock waves using explicit transition probabilities

    NASA Astrophysics Data System (ADS)

    Torres, Erik; Magin, Thierry

    2012-11-01

    A statistical model originally developed for electronic-translational energy transfer in atoms having multiple electronic states (Anderson et al, RGD15, 1986) is applied to the study of internal energy exchange in a polyatomic gas. The model is well-suited for gas kinetic simulations, because it provides an explicit expression for the transition probabilities between internal energy levels. All molecules possessing a given internal energy level are treated as a separate chemical species and all collisions involving exchange of internal energy thus become pseudo-chemical reactions. Post-collision energy levels of the two partners are determined by conserving the total energy of the collision pair and taking into account detailed balance. In the present work, DSMC simulations of relaxation in a stationary gas are performed and compared to those obtained by Anderson et al. Additionally, we apply the model to the simulation of rotational relaxation behind a normal shock wave.

  8. Thermal shock behaviour of tungsten after high flux H-plasma loading

    NASA Astrophysics Data System (ADS)

    Wirtz, M.; Linke, J.; Pintsuk, G.; De Temmerman, G.; Wright, G. M.

    2013-11-01

    Previous studies have shown that transient thermal shock loads induce crack networks on tungsten samples especially at low base temperatures. To achieve test conditions which are more relevant for the performance of tungsten-armoured plasma facing components in next step thermonuclear fusion devices tungsten tiles were exposed to high flux hydrogen-plasma in the linear plasma generator Pilot-PSI and the high heat flux ion beam test facility MARION. Subsequently, the cyclic transient heat load tests were done in the electron beam facility JUDITH 1. The induced damages after these combined tests were examined by microscopically means, profilometry and metallography. The comparison of the obtained results and damage characteristics with those obtained after thermal shock loading show that the preloading of tungsten targets with high flux hydrogen-plasma has significant influence on the thermal shock behaviour of tungsten in terms of crack distance, width, and depth as well as cracked area. Furthermore the plasma parameters, in particular pulse duration and sample temperature during loading, have strong impact on the damage pattern after thermal shock loading.

  9. High Energy Astrophysics Program

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This report reviews activities performed by members of the USRA (Universities Space Research Association) contract team during the six months during the reporting period (10/95 - 3/96) and projected activities during the coming six months. Activities take place at the Goddard Space Flight Center, within the Laboratory for High Energy Astrophysics. Developments concern instrumentation, observation, data analysis, and theoretical work in Astrophysics. Missions supported include: Advanced Satellite for Cosmology and Astrophysics (ASCA), X-ray Timing Experiment (XTE), X-ray Spectrometer (XRS), Astro-E, High Energy Astrophysics Science, Archive Research Center (HEASARC), and others.

  10. High Energy Astrophysics Program

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This report reviews activities performed-by members of the USRA contract team during the six months of the reporting period and projected activities during the coming six months. Activities take place at the Goddard Space Flight Center, visiting the Laboratory for High Energy Astrophysics. Developments concern instrumentation, observation, data analysis, and theoretical work in Astrophysics. Missions supported include: Advanced Satellite for Cosmology and Astrophysics (ASCA); X-ray Timing Experiment (XTE); X-ray Spectrometer (XRS); Astro-E; High Energy Astrophysics Science Archive Research Center (HEASARC), and others.

  11. On the effect of grain size on shock sensitivity of heterogeneous high explosives

    NASA Astrophysics Data System (ADS)

    Khasainov, B. A.; Ermolaev, B. S.; Presles, H.-N.; Vidal, P.

    Analysis of available data on dependence of the critical detonation diameter dcr of various heterogeneous condensed explosives on mean size of grains and voids demonstrated that in many cases surprising correlations between dcr and the initial specific surface area of heterogeneous explosives Ao exist, namely, dcr=α 1+α 2/A_o or 1/dcr=β 1+β 2A_o. The run distance to detonation in wedge test with sustained strong shock of constant amplitude also linearly correlates with 1/Ao, i.e. L{P= Const}=γ 1+γ 2/A_o. At the same time, the shock sensitivity reversal effect is often observed when grain size of HE is reduced. Apart from that Moulard (1989) found that detonation critical diameter of plastic bonded explosive with mono- and bimodal RDX grain size distribution depends nonmonotonously on mean grain size. Complicated dependence of shock sensitivity of heterogeneous explosives on their specific surface area can be explained based on comparison of the critical hot spot size a*(P) at given characteristic pressure behind shock wave P with the mean heterogeneity size /line{a}. At high characteristic pressure (relative to the critical ignition pressure) a* is small compared with /line{a} and all specific surface area of heterogeneous explosive is available for the hot spot growth process in accordance with the grain burn concept. However, when characteristic pressure of shock wave decreases, a*(P) increases and can become comparable with /line{a}. In this case only relatively large potential hot spots (with size a>a*) can result in self-supported hot spot growth process and shock sensitivity is controlled by the specific surface area which corresponds to only larger heterogeneities and can be significantly smaller than initial specific surface area.

  12. The low-energy interstellar spectrum of galactic electrons and implications for their re-acceleration at the heliospheric termination shock

    NASA Astrophysics Data System (ADS)

    Prinsloo, Phillip; Toit Strauss, Du; Potgieter, Marius

    2016-07-01

    Since the diffusive shock acceleration process of particles at any given energy is dependent on the shape of their distribution at lower energies, it becomes essential to specify the interstellar spectrum for electrons below 1 MeV to study the re-acceleration of these particles at the heliospheric termination shock. Informed by the results of both radio data surveys and galactic propagation modelling, a number of illustrative scenarios are considered for this very low-energy local interstellar spectrum. Using a cosmic-ray transport model and assuming rigidity-independent diffusion at the considered energies, the contribution of re-accelerated electrons to intensity levels is probed for each of the aforementioned scenarios. The magnitudes of the resultant intensity increases are concluded to be highly dependent on the spectral shape specified for interstellar spectra at these very low energies, with the softer distributions predictably yielding greater re-acceleration effects.

  13. Observational signatures of the influence of the interplanetary shocks on the associated low-energy particle events

    NASA Astrophysics Data System (ADS)

    Heras, A. M.; Sanahuja, B.; Sanderson, T. R.; Marsden, R. G.; Wenzel, K.-P.

    1994-01-01

    We have analyzed the temporal evolution of the upstream particle fluxes and anisotropies in a set of particle events associated with interplanetary shocks, detected by International Sun-Earth Explorer (ISEE) 3 during the period 1978-1980 in the 147-238 and 620-1000 keV energy ranges. In particular, we have studied those features that can perhaps be used as signatures of the history of the influence of the shock on the particle event. We have paid special attention to the evolution of the flux anisotropy that can carry relevant information on the contribution of shock accelerated particles to the total observed flux. Our analysis shows that during most events, long-lasting (between 5 and 36 hours) large anisotropies are observed upstream of the shock, supporting the hypothesis of continuous injection of shock accelerated paricles in the interplanetary medium while the shock is propagating outward from the Sun. The evolution of the anisotropy throughout each event shows a dependence on the longitude of the parent solar source. We have interpreted the observations considering that shock accelerated particles contribute significantly to the total observed flux from the time when the shock intersects the magnetic field line that connects with the observer. The heliocentric distance of this initial intersection point has been derived from the flux anisotropy observations for each event. The values obtained show a distribution with respect to the longitude of the solar source that can be reproduced with a simple model, which assumes a spherical shock with an angular extension approximately equals 100 deg and an archimedian spiral structure for the interplanetary magnetic field. The results of this work provide a further insight into both the importance of shock acceleration, as well as the influence of the large-scale shock structure in low-energy particle events.

  14. Instantaneous x-ray radiation energy from laser produced polystyrene plasmas for shock ignition conditions

    SciTech Connect

    Shang, Wanli; Wei, Huiyue; Li, Zhichao; Yi, Rongqing; Zhu, Tuo; Song, Tianmin; Huang, Chengwu; Yang, Jiamin

    2013-10-15

    Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 × 10{sup 14} to 1.8 × 10{sup 15} W/cm{sup 2}. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

  15. A study of high frequency vibrations due to pyrotechnic shocks in coupled systems

    NASA Astrophysics Data System (ADS)

    Lednik, D.; Pinnington, R. J.

    1991-10-01

    A method of predicting the vibrational response of complex structures to shock inputs is currently being developed. The possibility of using a combination of two approximate approaches is being examined: wave propagation analysis (WPA) and transient statistical energy analysis (TSEA). Some results of a theoretical investigation into the transient power flow between coupled beams are presented. TSEA and WPA predictions seem to be in good agreement with exact results, virtually independent of the coupling strength.

  16. Ion heating and energy partition at the heliospheric termination shock: hybrid simulations and analytical model

    SciTech Connect

    Gary, S Peter; Winske, Dan; Wu, Pin; Schwadron, N A; Lee, M

    2009-01-01

    The Los Alamos hybrid simulation code is used to examine heating and the partition of dissipation energy at the perpendicular heliospheric termination shock in the presence of pickup ions. The simulations are one-dimensional in space but three-dimensional in field and velocity components, and are carried out for a range of values of pickup ion relative density. Results from the simulations show that because the solar wind ions are relatively cold upstream, the temperature of these ions is raised by a relatively larger factor than the temperature of the pickup ions. An analytic model for energy partition is developed on the basis of the Rankine-Hugoniot relations and a polytropic energy equation. The polytropic index {gamma} used in the Rankine-Hugoniot relations is varied to improve agreement between the model and the simulations concerning the fraction of downstream heating in the pickup ions as well as the compression ratio at the shock. When the pickup ion density is less than 20%, the polytropic index is about 5/3, whereas for pickup ion densities greater than 20%, the polytropic index tends toward 2.2, suggesting a fundamental change in the character of the shock, as seen in the simulations, when the pickup ion density is large. The model and the simulations both indicate for the upstream parameters chosen for Voyager 2 conditions that the pickup ion density is about 25% and the pickup ions gain the larger share (approximately 90%) of the downstream thermal pressure, consistent with Voyager 2 observations near the shock.

  17. Shock tube/time-of-flight mass spectrometer for high temperature kinetic studies

    SciTech Connect

    Tranter, Robert S.; Giri, Binod R.; Kiefer, John H.

    2007-03-15

    A shock tube (ST) with online, time-of-flight mass spectrometric (TOF-MS) detection has been constructed for the study of elementary reactions at high temperature. The ST and TOF-MS are coupled by a differentially pumped molecular beam sampling interface, which ensures that the samples entering the TOF-MS are not contaminated by gases drawn from the cold end wall thermal boundary layer in the ST. Additionally, the interface allows a large range of postshock pressures to be used in the shock tube while maintaining high vacuum in the TOF-MS. The apparatus and the details of the sampling system are described along with an analysis in which cooling of the sampled gases and minimization of thermal boundary layer effects are discussed. The accuracy of kinetic measurements made with the apparatus has been tested by investigating the thermal unimolecular dissociation of cyclohexene to ethylene and 1,3-butadiene, a well characterized reaction for which considerable literature data that are in good agreement exist. The experiments were performed at nominal reflected shock wave pressures of 600 and 1300 Torr, and temperatures ranging from 1260 to 1430 K. The rate coefficients obtained are compared with the earlier shock tube studies and are found to be in very good agreement. As expected no significant difference is observed in the rate constant between pressures of 600 and 1300 Torr.

  18. A Search for Early High-Energy Afterglows in BATSE Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Giblin, Timothy W.

    2003-01-01

    The scope of this project was to perform a detailed search for the early high-energy afterglow component of gamma-ray bursts (GRBs) in the BATSE GRB data archive. GRBs are believed to be the product of shock waves generated in a relativistic outflow from the demise of extremely massive stars and/or binary neutron star mergers. The outflow undeniably encounters the ambient medium of the progenitor object and another shock wave is set up. A forward shock propagates into the medium and a reverse shock propagates through the ejecta. This "external" shock dissipates the kinetic energy of the ejecta in the form of radiation via synchrotron losses and slows the outflow eventually to a non-relativistic state. Radiation from the forward external shock is therefore expected to be long-lived, lasting days, weeks, and even months. This radiation is referred to as the 'afterglow'.

  19. High energy particle astronomy.

    NASA Technical Reports Server (NTRS)

    Buffington, A.; Muller, R. A.; Smith, L. H.; Smoot, G. F.

    1972-01-01

    Discussion of techniques currently used in high energy particle astronomy for measuring charged and neutral cosmic rays and their isotope and momentum distribution. Derived from methods developed for accelerator experiments in particle physics, these techniques help perform important particle astronomy experiments pertaining to nuclear cosmic ray and gamma ray research, electron and position probes, and antimatter searches.

  20. High Energy Astronomy Observatory

    NASA Technical Reports Server (NTRS)

    1980-01-01

    An overview of the High Energy Astronomy Observatory 2 contributions to X-ray astronomy is presented along with a brief description of the satellite and onboard telescope. Observations relating to galaxies and galactic clusters, black holes, supernova remnants, quasars, and cosmology are discussed.

  1. Half a century of continuous shock interaction investigations in the Joint Institute for High Temperatures of Russian Academy of Sciences

    NASA Astrophysics Data System (ADS)

    Bazhenova, T. V.; Golub, V. V.; Gvozdeva, L. G.; Kotelnikov, A. L.

    2014-07-01

    This article describes the history of the investigations of shock wave interactions at the Physical Gasdynamic Department, starting from the early 50s of the last century, when the first research related to missile reentry was made. The review focuses on a number of topics studied over more than 50 years and includes the study of strong shock waves, where it is necessary to take into account the physicochemical transformations in gases, shock wave reflection, diffraction, interaction with the boundary layer and with the nozzle, as well as detonation wave formation and interactions. The investigation of shock wave interactions is a current topic at the Joint Institute for High Temperatures of the Russian Academy of Sciences. Some new results are observed: the formation of impulse jets and the self-ignition of a cold hydrogen jet, diffraction of 3D shock waves, and the effect of an impulse jet and diffracted shock wave on an obstacle.

  2. Investigation of normal shock inlets for highly maneuverable aircraft

    NASA Technical Reports Server (NTRS)

    Martin, A. W.

    1977-01-01

    Concepts are investigated for obtaining both low cowl drag and good inlet performance at high angles of attack. The effect of a canard on inlet performance for a kidney shaped inlet in each of two vertical locations is discussed along with a sharp lip two dimensional inlet on a canardless forebody.

  3. Highly Siderophile Elements in Shocked and Unshocked Chondrites

    NASA Technical Reports Server (NTRS)

    Horan, M. F.; Walker, R. J.; Rubin, A. E.

    2001-01-01

    High precision abundances of Re, Os, Pt, Ir, Ru, and Pd are combined with Re-Os isotopic data to demonstrate that HSE provide a distinctive fingerprint for each of the chondrite groups. Additional information is contained in the original extended abstract.

  4. Evaluation of five biocarriers as supports for immobilized bacteria: Comparative performance during high chemical loading, acid shocking, drying and heat shocking

    SciTech Connect

    Heitkamp, M.A.; Adams, W.J. . Environmental Sciences Center); Camel, V. )

    1993-06-01

    Immobilized bacteria technology (IBT) utilizes inert biocarriers to support high concentrations of chemical-degrading bacteria in reactors designed to provide optimal conditions for microbial activity. This study evaluated IBT performance inpacked bed reactors (PBRs) using a porous inorganic biocarrier (diatomaceous earth), nonporous biocarriers (glass beads), and organic biocarriers having carbon adsorption properties (granular activated carbon) with different porosity. Each reactor was challenged with high chemical loading, acid, dryness, and heat shock conditions. Benchtop PBSs inoculated with a p-nitrophenol (PNP)-degrading Pseudomonas sp. and fed a synthetic waste containing 100 to 1,300 mg/L of PNP showed removal of PNP from effluents within 24 h of start-up. Chemical loading studies showed maximum PNP removal rates of 6.45 to 7.35 kg/m[sup 3]/d for bacteria in PBRs containing diatomaceous earth beads, glass beads, and activated coconut carbon. A lower PNP removal rate of 1.47 kg/m[sup 3]/d was determined for the activated anthracite carbon, and this PBR responded more slowly to increases in chemical loading. The PBR containing bacteria immobilized on activated coconut carbon showed exceptional tolerance to acid shocking, drying, and heat shocking by maintaining PNP removal rates > 85% throughout the entire study. The other biocarriers showed nearly complete loss of PNP degradation during the perturbations, but all recovered high rates of PNP degradation (> 98% removal) within 48 h after an acid shock at pH2, within 8 d after an acid shock at pH 1.0, within 24 h after drying for 72 h, and within 48 h of heat shocking. The resiliency and high chemical removal efficiency demonstrated by immobilized bacteria in this study support the concept of using IBT for the biotreatment of industrial wastes..

  5. A planar shock isolation system with high-static-low-dynamic-stiffness characteristic based on cables

    NASA Astrophysics Data System (ADS)

    Ma, Yanhui; He, Minghua; Shen, Wenhou; Ren, Gexue

    2015-12-01

    In this paper, a simple and designable shock isolation system with ideal high-static-low-dynamic-stiffness (HSLDS) is proposed, which is intended for the horizontal plane shock isolation application. In this system, the isolated object is suspended by several bearing cables and constrained by a number of uniformly distributed pretensioned cables in the horizontal plane, where the low dynamic stiffness of the system is main controlled by the pretension of the planar cables, whilst the high static stiffness is determined by the axial stiffness of the planar cables and their geometric settings. To obtain the HSLDS characteristic of the system, a brief theoretical description of the relationship between the restoring force and displacement is derived. By obtaining the three-order Taylor expansion with sufficient accuracy of the restoring force, influence of planar cable parameters on the low dynamic and high static stiffness is thus given, therefore, the required HSLDS isolator can be easily designed by adjusting the planar cable length, pretension and tensile stiffness. Finally, the isotropy characteristic of the restoring force of the system with different numbers of planar cables is investigated. To evaluate the performance of the system, a rigid isolated object and flexible cables coupling simulation model considering the contacts of the system is established by using multibody dynamics approach. In this model, flexible cables are simulated by 3-node cable element based on the absolute nodal coordinate formulation; the contact between cable and isolated object is simulated based on Hertz contact theory. Finally, the time-domain shock excitation is converted from the design shock spectrum on the basis of BV043/85 criterion. The design procedure of this isolator and some useful guidelines for choosing cable parameters are presented. In addition, a summary about the performance of the isolators with different numbers of cables shocking in an arbitrary direction is

  6. High Energy Density Sciences with High Power Lasers at SACLA

    NASA Astrophysics Data System (ADS)

    Kodama, Ryosuke

    2013-10-01

    One of the interesting topics on high energy density sciences with high power lasers is creation of extremely high pressures in material. The pressures of more than 0.1 TPa are the energy density corresponding to the chemical bonding energy, resulting in expectation of dramatic changes in the chemical reactions. At pressures of more than TPa, most of material would be melted on the shock Hugoniot curve. However, if the temperature is less than 1eV or lower than a melting point at pressures of more than TPa, novel solid states of matter must be created through a pressured phase transition. One of the interesting materials must be carbon. At pressures of more than TPa, the diamond structure changes to BC and cubic at more than 3TPa. To create such novel states of matter, several kinds of isentropic-like compression techniques are being developed with high power lasers. To explore the ``Tera-Pascal Science,'' now we have a new tool which is an x-ray free electron laser as well as high power lasers. The XFEL will clear the details of the HED states and also efficiently create hot dense matter. We have started a new project on high energy density sciences using an XFEL (SACLA) in Japan, which is a HERMES (High Energy density Revolution of Matter in Extreme States) project.

  7. Energy Feedback via Shocks in Starburst Environments: the Case of 30 Doradus

    NASA Astrophysics Data System (ADS)

    Yeh, Sherry; Seaquist, Ernie; Matzner, Christopher

    2011-08-01

    We propose to image the entire 30 Doradus nebula in the [FeII] emission line at 1.64 micron with NEWFIRM on the CTIO 4-m telescope. The proposed observation will reveal the spatial distribution of shocks in the region, which serves as a strong complement to the NEWFIRM H_2 and Br(gamma) images we already obtained, and our proposed spectroscopic observations using the NTT. We aim to quantify the fraction of each energy input (shock and radiation) in the 30 Doradus PDR with the H_2/Br(gamma), [FeII]/H_2, and [FeII]/Br(gamma) ratios, and to ultimately better understand subsequent star formation in starburst regions.

  8. Waves at Oblique Shocks and the Highest Cosmic Ray Energies in Tychos SNR

    NASA Astrophysics Data System (ADS)

    Laming, Martin

    2015-10-01

    We describe a new model for the stripes of synchrotron radiation seen in the remnant of Tychos supernova, in terms of Alfven wave generation by the Bell Instability, followed by reflection, refraction and damping at an oblique shock. Based on estimates for damping rates due to turbulent cascade and transit time damping, we estimate the dependence of the visibility of the stripes on the shock obliquity, and determine a maximum cosmic ray energy in Tychos SNR in the range 6 x 1014 - 1 x 1015 eV, close to the knee in the cosmic ray spectrum. With such an understanding, synchrotron stripes ought in principle to be more commonly seen in SNRs, and should constitute a prime science topic for any future X-ray astronomy observatory.

  9. A PFV/sub 2/ accelerometer for high shock applications

    SciTech Connect

    Tise, B.; Smith, T.

    1989-08-01

    This report describes the development, fabrication, and testing of a high-g piezoelectric accelerometer that uses PVF/sub 2/ as the piezoelectric transducer. The accelerometer is designed to continuously measure accelerations up to 1000,000 g. The device is packages in a 3/8'' hex head bolt and can include a built-in hybrid buffer to provide a low-output impedance analog signal. Included in this report are fabrication procedures, mechanical drawings, and software listings for test data analysis programs. 30 refs., 21 figs.

  10. Ultra-high-speed studies of shock phenomena in a miniaturized system: A preliminary evaluation

    SciTech Connect

    Trott, W.M.; Erickson, K.L.

    1997-09-01

    A laboratory-scale experimental test system for small-scale of shock phenomena has been assembled. This system uses a variety of miniature test platforms in which shock loading is provided by laser-driven flyer impact. Acceptor materials include thin-film explosives and high-density metal foils. Optical access is provided for high-speed optical diagnostics such as optically recording velocity interferometry and single-pulse Raman spectroscopy. The experimental assembly for Raman studies features a common laser source for both flyer generation and excitation of Raman scattering (to achieve high timing precision) and a detection scheme that uses the coupling fiber for the excitation source to collect with high efficiency backscattered Raman light. Preliminary system evaluation experiments indicate that detailed particle velocity studies of the dynamic material properties of high-density metals under short-pulse, high-strain-rate loading can be performed in a miniaturized test configuration. Single-pulse Raman studies on shock compressed thin film explosives also appear feasible if the thickness and grain structure of these films can be tailored to enhance the Raman scattering signal sufficiently. Possible improvements in the experimental design and a number of likely applications of these techniques are also discussed.

  11. Theoretical High Energy Physics

    SciTech Connect

    Christ, Norman H.; Weinberg, Erick J.

    2014-07-14

    we provide reports from each of the six faculty supported by the Department of Energy High Energy Physics Theory grant at Columbia University. Each is followed by a bibliography of the references cited. A complete list of all of the publications in the 12/1/2010-04/30/2014 period resulting from research supported by this grant is provided in the following section. The final section lists the Ph.D. dissertations based on research supported by the grant that were submitted during this period.

  12. A high-order WENO-Z finite difference based particle-source-in-cell method for computation of particle-laden flows with shocks

    SciTech Connect

    Jacobs, Gustaaf B. Don, W.-S.

    2009-03-20

    A high-order particle-source-in-cell (PSIC) algorithm is presented for the computation of the interaction between shocks, small scale structures, and liquid and/or solid particles in high-speed engineering applications. The improved high-order finite difference weighted essentially non-oscillatory (WENO-Z) method for solution of the hyperbolic conservation laws that govern the shocked carrier gas flow, lies at the heart of the algorithm. Finite sized particles are modeled as points and are traced in the Lagrangian frame. The physical coupling of particles in the Lagrangian frame and the gas in the Eulerian frame through momentum and energy exchange, is numerically treated through high-order interpolation and weighing. The centered high-order interpolation of the fluid properties to the particle location is shown to lead to numerical instability in shocked flow. An essentially non-oscillatory interpolation (ENO) scheme is devised for the coupling that improves stability. The ENO based algorithm is shown to be numerically stable and to accurately capture shocks, small flow features and particle dispersion. Both the carrier gas and the particles are updated in time without splitting with a third-order Runge-Kutta TVD method. One and two-dimensional computations of a shock moving into a particle cloud demonstrates the characteristics of the WENO-Z based PSIC method (PSIC/WENO-Z). The PSIC/WENO-Z computations are not only in excellent agreement with the numerical simulations with a third-order Rusanov based PSIC and physical experiments in [V. Boiko, V.P. Kiselev, S.P. Kiselev, A. Papyrin, S. Poplavsky, V. Fomin, Shock wave interaction with a cloud of particles, Shock Waves, 7 (1997) 275-285], but also show a significant improvement in the resolution of small scale structures. In two-dimensional simulations of the Mach 3 shock moving into forty thousand bronze particles arranged in the shape of a rectangle, the long time accuracy of the high-order method is demonstrated

  13. Acceleration of ions and electrons to near-cosmic ray energies in a perpendicular shock: The January 6, 1978 event

    NASA Technical Reports Server (NTRS)

    Krimigis, S. M.; Sarris, E. T.

    1985-01-01

    Acceleration of energetic ions to approx 200 MeV and electrons to approx 2 MeV were detected by the Low Energy Charged Particle (LECP) instrument on Voyager 2 in association with a quasiperpendicular shock of theta sub Bn - 87.5 deg at 1.9 AU. The measurments, obtained at a time resolution of approx. 1.2 sec, reveal structure of the energetic particle intensity enhancements down to a scale of the order of the particle gyroradius, and suggest that acceleration takes place within a gyrodiameter of the shock. The observations are consistent with the prediction of the shock drift acceleration (SDA) mechanism. The absence of any fluctuations in the magnetic field during the shock passage suggest that turbulence is not essential to the shock acceleration process in the interplanetary medium.

  14. Early Fluid Resuscitation and High Volume Hemofiltration Decrease Septic Shock Progression in Swine

    PubMed Central

    Zhao, Ping; Zheng, Ruiqiang; Xue, Lu; Zhang, Min; Wu, Xiaoyan

    2015-01-01

    This study aimed to assess the effects of early fluid resuscitation (EFR) combined with high volume hemofiltration (HVHF) on the cardiopulmonary function and removal of inflammatory mediators in a septic shock swine model. Eighteen swine were randomized into three groups: control (n = 6) (extracorporeal circulating blood only), continuous renal replacement therapy (CRRT) (n = 6; ultrafiltration volume = 25 mL/Kg/h), and HVHF (n = 6; ultrafiltration volume = 85 mL/Kg/h). The septic shock model was established by intravenous infusion of lipopolysaccharides (50 µg/kg/h). Hemodynamic parameters (arterial pressure, heart rate, cardiac output, stroke volume variability, left ventricular contractility, systemic vascular resistance, and central venous pressure), vasoactive drug parameters (dose and time of norepinephrine and hourly fluid intake), pulmonary function (partial oxygen pressure and vascular permeability), and cytokines (interleukin-6 and interleukin-10) were observed. Treatment resulted in significant changes at 4–6 h. HVHF was beneficial, as shown by the dose of vasoactive drugs, fluid intake volume, left ventricular contractility index, and partial oxygen pressure. Both CRRT and HVHF groups showed improved removal of inflammatory mediators compared with controls. In conclusion, EFR combined with HVHF improved septic shock in this swine model. The combination decreased shock progression, reduced the need for vasoactive drugs, and alleviated the damage to cardiopulmonary functions. PMID:26543849

  15. High-Speed Imaging of Shock-Wave Motion in Aviation Security Research

    NASA Astrophysics Data System (ADS)

    Anderson, B. W.; Settles, G. S.; Miller, J. D.; Keane, B. T.; Gatto, J. A.

    2001-11-01

    A high-speed drum camera is used in conjunction with Penn State's Full-Scale Schlieren Facility to capture blast wave phenomena in aviation security scenarios. Several hundred photographic frames at a rate of 45k frames/sec allow the imaging of entire explosive events typical of blasts inside an aircraft fuselage. The large (2.3 x 2.9 m) schlieren field-of-view further allows these experiments to be done at or near full-scale. Shock waves up to Mach 1.3 are produced by detonating small balloons filled with an oxygen-acetylene gas mixture. Blasts underneath actual aircraft seats occupied by mannequins reveal shock motion inside a passenger cabin. Blasts were also imaged within the luggage container of a 3/5-scale aircraft fuselage, including hull-holing, as occurred in the Pan Am 103 incident. Drum-camera frames are assembled into digital video clips of several seconds duration, which will be shown in the presentation. These brief movies provide the first-ever visualization of shock motion due to explosions onboard aircraft. They also illustrate the importance of shock imaging in aircraft-hardening experiments, and they provide data to validate numerical predictions of such events. Supported by FAA Grant 99-G-032.

  16. Heterodyne Velocimetry measurements on solids shock driven by high power lasers

    NASA Astrophysics Data System (ADS)

    Mercier, Patrick; Benier, Jacky; Frugier, Pierre-Antoine; Sollier, Arnaud; Lescoute, Emilen; Cuq-Lelandais, Jean-Paul; Gay, Elise; de Resseguier, Thibaut; Berthe, Laurent; Boustie, Michel; Nivard, Mariette; Claverie, Alain; Rabec Le Gloahec, Marc

    2009-06-01

    A new Heterodyne Velocimeter (PDV) is under development at CEA for high explosive experimentations. Recently, we used it onto metallic target shock driven by high power laser. The aim is to test the ability of this means to reveal the propagation and the effects of shocks into materials, at extremely high strain rate and fast variations into the loading evolution. Spallation and fragmentation experiments carried out on aluminum samples, were performed on the LULI lasers at the Ecole Polytechnique, with both VISAR and HV diagnostics. Comparisons reveal a very good consistency of both experimental results. In addition, HV diagnostic evidence several levels of velocity in the experiment of fragmentation. Interpretation of these measurements is supported by transverse shadowgraphy analysis.

  17. Multiphysics Simulations of Hot-Spot Initiation in Shocked Insensitive High-Explosive

    NASA Astrophysics Data System (ADS)

    Najjar, Fady; Howard, W. M.; Fried, L. E.

    2010-11-01

    Solid plastic-bonded high-explosive materials consist of crystals with micron-sized pores embedded. Under mechanical or thermal insults, these voids increase the ease of shock initiation by generating high-temperature regions during their collapse that might lead to ignition. Understanding the mechanisms of hot-spot initiation has significant research interest due to safety, reliability and development of new insensitive munitions. Multi-dimensional high-resolution meso-scale simulations are performed using the multiphysics software, ALE3D, to understand the hot-spot initiation. The Cheetah code is coupled to ALE3D, creating multi-dimensional sparse tables for the HE properties. The reaction rates were obtained from MD Quantum computations. Our current predictions showcase several interesting features regarding hot spot dynamics including the formation of a "secondary" jet. We will discuss the results obtained with hydro-thermo-chemical processes leading to ignition growth for various pore sizes and different shock pressures.

  18. 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.

  19. Initial observations of low energy charged particles near the earth's bow shock on ISEE-1

    NASA Technical Reports Server (NTRS)

    Ipavich, F. M.; Gloeckler, G.; Fan, C. Y.; Fisk, L. A.; Hovestadt, D.; Klecker, B.; Scholer, M.; Ogallagher, J. J.

    1979-01-01

    Initial measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE 1 are reported. ULECA is an electrostatic deflection - total energy sensor consisting of a collimator, a deflection analyzer, and an array of solid-state detectors. The position of a given detector, which determines the energy per charge of an incident particle, together with the measured energy, determines the particle's charge state. It is found that a rich variety of phenomena are operative in the transthermal energy regime (about 10 keV/Q to 100 keV/Q) covered by ULECA. Specifically, observations are presented of locally accelerated protons, alpha particles, and heavier ions in the magnetosheath and upstream of earth's bow shock. Preliminary analysis indicates that the behavior of these locally accelerated particles is most similar at the same energy per charge.

  20. Heterotrophic microbial colonization of the interior of impact-shocked rocks from Haughton impact structure, Devon Island, Nunavut, Canadian High Arctic

    NASA Astrophysics Data System (ADS)

    Fike, David A.; Cockell, Charles; Pearce, David; Lee, Pascal

    2002-10-01

    The polar desert is one of the most extreme environments on Earth. Endolithic organisms can escape or mitigate the hazards of the polar desert by using the resources available in the interior of rocks. We examined endolithic communities within crystalline rocks that have undergone shock metamorphism as a result of an asteroid or comet impact. Specifically, we present a characterization of the heterotrophic endolithic community and its environment in the interior of impact-shocked gneisses and their host polymict breccia from the Haughton impact structure on Devon Island, Nunavut, Canadian High Arctic. Microbiological colonization of impact-shocked rocks is facilitated by impact-induced fissures and cavities, which occur throughout the samples, the walls of which are lined with high abundances of biologically important elements owing to the partial volatilization of minerals within the rock during the impact. 27 heterotrophic bacteria were isolated from these shocked rocks and were identified by 16S rDNA sequencing. The isolates from the shocked gneiss and the host breccia are similar to each other, and to other heterotrophic communities isolated from polar environments, suggesting that the interiors of the rocks are colonized by microorganisms from the surrounding country rocks and soils. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis were used to identify the chemical composition of the shocked materials and to document the in situ growth of microbes in their interiors. The identification of these heterotrophic communities within impact-shocked crystalline rocks extends our knowledge of the habitable biosphere on Earth. The colonization of the interiors of these samples has astrobiological applications both for considering terrestrial, microbiological contamination of meteorites from the Antarctic ice sheet and for investigating possible habitats for microbial

  1. High energy from space

    NASA Technical Reports Server (NTRS)

    Margon, Bruce; Canizares, Claude; Catura, Richard C.; Clark, George W.; Fichtel, Carl E.; Friedman, Herbert; Giacconi, Riccardo; Grindlay, Jonathan E.; Helfand, David J.; Holt, Stephen S.

    1991-01-01

    The following subject areas are covered: (1) important scientific problems for high energy astrophysics (stellar activity, the interstellar medium in galaxies, supernovae and endpoints of stellar evolution, nucleosynthesis, relativistic plasmas and matter under extreme conditions, nature of gamma-bursts, identification of black holes, active nuclei, accretion physics, large-scale structures, intracluster medium, nature of dark matter, and the X- and gamma-ray background); (2) the existing experimental programs (Advanced X-Ray Astrophysics Facility (AXAF), Gamma Ray Observatory (GRO), X-Ray Timing Explorer (XTE), High Energy Transient Experiment (HETE), U.S. participation in foreign missions, and attached Shuttle and Space Station Freedom payloads); (3) major missions for the 1990's; (4) a new program of moderate missions; (5) new opportunities for small missions; (6) technology development issues; and (7) policy issues.

  2. High energy transients

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.

    1984-01-01

    A meeting was convened on the campus of the University of California at Santa Cruz during the two-week interval July 11 through July 22, 1983. Roughly 100 participants were chosen so as to give broad representation to all aspects of high energy transients. Ten morning review sessions were held in which invited speakers discussed the current status of observations and theory of the above subjects. Afternoon workshops were also held, usually more than one per day, to informally review various technical aspects of transients, confront shortcomings in theoretical models, and to propose productive courses for future research. Special attention was also given to the instrumentation used to study high energy transient and the characteristics and goals of a dedicated space mission to study transients in the next decade were determined. A listing of articles written by various members of the workshop is included.

  3. On the acceleration of ions by interplanetary shock waves. 3: High time resolution observations of CIR proton events

    NASA Technical Reports Server (NTRS)

    Pesses, M. E.; Vanallen, J. A.; Tsurutani, B. T.; Smith, E. J.

    1981-01-01

    Observations within + or - 3 hours of corotating interaction region (CIR) shock waves of proton intensities, pitch angle distribution and crude differential energy spectra of the range of 0.6 E sub p 3.4 MeV are presented. The principle result is the evidence for the persistent flow of particles away from the shock. The observations are found to be in good agreement with the hypothesis of local interplanetary shock acceleration by the shock drift and compression mechanisms. The same set of observations strongly suggest that transit time damping does not play an important role in the acceleration of protons to 1 MeV in the immediate vicinity of CIR shocks.

  4. High Energy Density Microwaves

    SciTech Connect

    Phillips, R.M.

    1999-04-01

    These proceedings represent papers presented at the RF98 Workshop entitled `High Energy Density Microwaves` held in California in October, 1998. The topics discussed were predominantly accelerator{minus}related. The Workshop dealt, for the most part, with the generation and control of electron beams, the amplification of RF signals, the design of mode converters, and the effect of very high RF field gradients. This Workshop was designed to address the concerns of the microwave tube industry worldwide, the plasma physicists who deal with very high beam currents and gigawatts of RF power, and researchers in accelerator centers around the world. Papers were presented on multibeam klystrons, gyrotron development, plasmas in microwave tubes, RF breakdown, and alternatives to conventional linear coliders at 1 TeV and above. The Workshop was partially sponsored by the US Department of Energy. There were 46 papers presented at the conference,out of which 19 have been abstracted for the Energy,Science and Technology database.(AIP)

  5. Dissipative issue of high-order shock capturing schemes with non-convex equations of state

    NASA Astrophysics Data System (ADS)

    Heuzé, Olivier; Jaouen, Stéphane; Jourdren, Hervé

    2009-02-01

    It is well known that, closed with a non-convex equation of state (EOS), the Riemann problem for the Euler equations allows non-standard waves, such as split shocks, sonic isentropic compressions or rarefaction shocks, to occur. Loss of convexity then leads to non-uniqueness of entropic or Lax solutions, which can only be resolved via the Liu-Oleinik criterion (equivalent to the existence of viscous profiles for all admissible shock waves). This suggests that in order to capture the physical solution, a numerical scheme must provide an appropriate level of dissipation. A legitimate question then concerns the ability of high-order shock capturing schemes to naturally select such a solution. To investigate this question and evaluate modern as well as future high-order numerical schemes, there is therefore a crucial need for well-documented benchmarks. A thermodynamically consistent C∞ non-convex EOS that can be easily introduced in Eulerian as well as Lagrangian hydrocodes for test purposes is here proposed, along with a reference solution for an initial value problem exhibiting a complex composite wave pattern (the Bizarrium test problem). Two standard Lagrangian numerical approaches, both based on a finite volume method, are then reviewed (vNR and Godunov-type schemes) and evaluated on this Riemann problem. In particular, a complete description of several state-of-the-art high-order Godunov-type schemes applicable to general EOSs is provided. We show that this particular test problem reveals quite severe when working on high-order schemes, and recommend it as a benchmark for devising new limiters and/or next-generation highly accurate schemes.

  6. FORMATION OF COSMIC CRYSTALS IN HIGHLY SUPERSATURATED SILICATE VAPOR PRODUCED BY PLANETESIMAL BOW SHOCKS

    SciTech Connect

    Miura, H.; Yamada, J.; Tsukamoto, K.; Nozawa, J.; Tanaka, K. K.; Yamamoto, T.; Nakamoto, T.

    2010-08-10

    Several lines of evidence suggest that fine silicate crystals observed in primitive meteorite and interplanetary dust particles (IDPs) nucleated in a supersaturated silicate vapor followed by crystalline growth. We investigated evaporation of {mu}m-sized silicate particles heated by a bow shock produced by a planetesimal orbiting in the gas in the early solar nebula and condensation of crystalline silicate from the vapor thus produced. Our numerical simulation of shock-wave heating showed that these {mu}m-sized particles evaporate almost completely when the bow shock is strong enough to cause melting of chondrule precursor dust particles. We found that the silicate vapor cools very rapidly with expansion into the ambient unshocked nebular region; for instance, the cooling rate is estimated to be as high as 2000 K s{sup -1} for a vapor heated by a bow shock associated with a planetesimal of radius 1 km. The rapid cooling of the vapor leads to nonequilibrium gas-phase condensation of dust at temperatures much lower than those expected from the equilibrium condensation. It was found that the condensation temperatures are lower by a few hundred K or more than the equilibrium temperatures. This explains the results of the recent experimental studies of condensation from a silicate vapor that condensation in such large supercooling reproduces morphologies similar to those of silicate crystals found in meteorites. Our results strongly suggest that the planetesimal bow shock is one of the plausible sites for formation of not only chondrules but also other cosmic crystals in the early solar system.

  7. Prevention of fatal hemorrhagic shock in dog by pretreatment with chronic high-salt diet.

    PubMed

    Rocchini, A P; Gallagher, K P; Botham, M J; Lemmer, J H; Szpunar, C A; Behrendt, D

    1985-09-01

    The ability of a chronic high-salt diet to prevent fatal hemorrhagic shock was examined in 36 mongrel dogs. Twenty-one dogs received a dietary supplement of 9 g sodium chloride/day for 6 wk, and 15 dogs received the same basic diet for 6 wk but without the sodium chloride supplement. Hemorrhagic shock was induced in all dogs by bleeding into an overhanging sealed reservoir. After 3 h of shock, salt-pretreated dogs had a lower systemic vascular resistance of 0.70 +/- 0.02 versus 1.44 +/- 0.04 mmHg X ml-1 X min X kg (P less than 0.01) and a higher cardiac output of 53 +/- 3 versus 26 +/- 3 ml X min-1 X kg-1 (P less than 0.01) than was observed in controls. At 2.5 h of shock, the salt-pretreated dogs also experienced an increase in gastrointestinal (P less than 0.01), hepatic arterial, (P less than 0.05), kidney (P less than 0.05), brain (P less than 0.01), and heart blood flows (P less than 0.001) compared with 0.5 h of shock, whereas the control dogs experienced no increased flow during this same period. We also observed that after 3 h of hypotension there was a significantly smaller increase in plasma renin activity in the salt-pretreated dogs. Administration of 0.1 U X kg-1 X min-1 of hog renin eliminated the differences in systemic vascular resistance, cardiac output, and survival in five salt-pretreated dogs. PMID:3929625

  8. Hot-spot contributions in shocked high explosives from mesoscale ignition models

    NASA Astrophysics Data System (ADS)

    Levesque, G.; Vitello, P.; Howard, W. M.

    2013-06-01

    High explosive performance and sensitivity is strongly related to the mesoscale defect densities. Bracketing the population of mesoscale hot spots that are active in the shocked ignition of explosives is important for the development of predictive reactive flow models. By coupling a multiphysics-capable hydrodynamics code (ale3d) with a chemical kinetics solver (cheetah), we can parametrically analyze different pore sizes undergoing collapse in high pressure shock conditions with evolving physical parameter fields. Implementing first-principles based decomposition kinetics, burning hot spots are monitored, and the regimes of pore sizes that contribute significantly to burnt mass faction and those that survive thermal conduction on the time scales of ignition are elucidated. Comparisons are drawn between the thermal explosion theory and the multiphysics models for the determination of nominal pore sizes that burn significantly during ignition for the explosive 1,3,5-triamino-2,4,6-trinitrobenzene.

  9. The spectral energy distribution of compact jets powered by internal shocks

    NASA Astrophysics Data System (ADS)

    Malzac, Julien

    2014-09-01

    Internal shocks caused by fluctuations of the outflow velocity are likely to power the radio-to-IR emission of the compact jets of X-ray binaries. The dynamics of internal shocks and the resulting spectral energy distribution (SED) of the jet are very sensitive to the time-scales and amplitudes of the velocity fluctuations injected at the base of the jet. I present a new code designed to simulate the synchrotron emission of a compact jet powered by internal shocks. I also develop a semi-analytical formalism allowing one to estimate the observed SED of the jet as a function of the Power Spectral Density (PSD) of the assumed fluctuations of the Lorentz factor. I discuss the cases of a sine modulation of the Lorentz factor and Lorentz factor fluctuations with a power-law PSD shape. Independently of the details of the model, the observed nearly flat SEDs are obtained for PSDs of Lorentz factor fluctuations that are close to a flicker noise spectrum (i.e. P(f ) ∝ 1/f ). The model also presents a strong wavelength-dependent variability that is similar to that observed in these sources.

  10. Energy convergence effect and jet phenomenon of shock-heavy spherical bubble interaction

    NASA Astrophysics Data System (ADS)

    Zou, LiYong; Zhai, ZhiGang; Liu, JinHong; Wang, YanPing; Liu, CangLi

    2015-12-01

    We present computational results on the evolution of the shock-accelerated heavy bubbles surrounded by nitrogen with the Atwood number A t = 0.497-0.677 and the emphasis is on the jet phenomenon caused by the shock focusing. The multi-fluid Eulerian equation is solved by a finite volume method based on MUSCL-Hancock approach. Based on the numerical schlieren and the distributions of density and pressure, it is found that there are three typical jet structures (outward jet, no jet, inward jet) for different combinations of gas mixture inside the bubble which determine the position of shock focusing relative to the downstream pole of the heavy bubble (upstream of the pole, at the pole, downstream the pole). Compared with the inward jet, the velocity of outward jet is obviously larger. As A t increases, the moment of jet formation is postponed, and the maximal values and magnifications of pressure and density increase distinctly. Therefore, the energy convergence effects are heavily enhanced with the increase of bubble gas density.

  11. An Investigation of High-Order Shock-Capturing Methods for Computational Aeroacoustics

    NASA Technical Reports Server (NTRS)

    Casper, Jay; Baysal, Oktay

    1997-01-01

    Topics covered include: Low-dispersion scheme for nonlinear acoustic waves in nonuniform flow; Computation of acoustic scattering by a low-dispersion scheme; Algorithmic extension of low-dispersion scheme and modeling effects for acoustic wave simulation; The accuracy of shock capturing in two spatial dimensions; Using high-order methods on lower-order geometries; and Computational considerations for the simulation of discontinuous flows.

  12. High-pressure behavior of carbon by laser-generated shocks

    NASA Astrophysics Data System (ADS)

    Batani, D.; Stabile, H.; Canova, F.; Koenig, M.; Benuzzi, A.; Nishimura, H.; Ochi, Y.; Ullschmied, J.; Skala, J.; Kralikova, B.; Pfeifer, M.; Mocek, T.; Präg, A.

    2007-09-01

    We present experimental data for the carbon equation of state (EOS) at Megabar pressures obtained by laser-driven shock waves. Experiments were performed at the PALS and LULI laboratories using carbon samples with two different values of initial density in order to explore a wider region of the phase diagram. Previously unreached pressures were obtained. The results are compared with previous experiments and with available theoretical models and seem to show high compressibility of carbon at Megabar pressures.

  13. Modeling Hot-Spot Contributions in Shocked High Explosives at the Mesoscale

    SciTech Connect

    Harrier, Danielle

    2015-08-12

    When looking at performance of high explosives, the defects within the explosive become very important. Plastic bonded explosives, or PBXs, contain voids of air and bonder between the particles of explosive material that aid in the ignition of the explosive. These voids collapse in high pressure shock conditions, which leads to the formation of hot spots. Hot spots are localized high temperature and high pressure regions that cause significant changes in the way the explosive material detonates. Previously hot spots have been overlooked with modeling, but now scientists are realizing their importance and new modeling systems that can accurately model hot spots are underway.

  14. Early-time evolution of a radiative shock

    NASA Astrophysics Data System (ADS)

    Kuranz, C. C.; Drake, R. P.; Huntington, C. M.; Krauland, C. M.; Di Stefano, C. A.; Trantham, M.; Grosskopf, M. J.; Klein, S. R.; Marion, D. C.

    2013-06-01

    We have performed high-energy-density physics experiments with large radiative fluxes, relevant to radiative shocks in our universe. These experiments were performed at the Omega Laser facility and used a laser irradiance of 7.2 × 1014 W cm-2 to launch a Be disk into low-density Xe gas. The radiative shocks were observed early in time as the dense shocked Xe layer began to form. The average shock position indicates that the shock is moving over 130 km s-1. Data are compared to simulation output from the CRASH code, which was developed at the Center for Radiative Shock Hydrodynamics at the University of Michigan.

  15. Impact of Pickup Ions on the Shock Front Nonstationarity and Energy Dissipation of the Heliospheric Termination Shock: Two-dimensional Full Particle Simulations and Comparison with Voyager 2 Observations

    NASA Astrophysics Data System (ADS)

    Yang, Zhongwei; Liu, Ying D.; Richardson, John D.; Lu, Quanming; Huang, Can; Wang, Rui

    2015-08-01

    Voyager 2 (V2) observed multiple crossings of the heliospheric termination shock (TS) on 2007 August 31-September 1 at a distance of 84 AU from the Sun. Here, for the first time, we present two-dimensional particle-in-cell (PIC) simulations of the TS self-consistently including pickup ions (PUIs), and compare the simulation results with V2 observations. We find that (1) PUIs play a key role in the energy dissipation of the TS, and most of the incident ion kinetic energy is transferred to the thermal energy of PUIs. The PIC simulation indicates that, for the upstream parameters chosen for V2 conditions, the density of PUIs is about 25% and the PUIs gain the largest fraction (approximately 86.6%) of downstream thermal pressure. (2) The simulated heliosheath ion distribution function is a superposition of a cold core formed by transmitted solar wind ions (SWIs), with the shoulders contributed by the hot reflected SWIs and directly transmitted PUIs, and the wings of the distribution dominated by the very hot reflected PUIs. The V2 Faraday cups observed the cool core of the distribution, and so they only saw the tip of the iceberg. (3) The nonstationarity of the shock front is mainly caused by ripples along the shock front which form even if the percentage of PUIs is high. These simulation results agree reasonably well with the V2 experimental data. The relevance of the shock front ripples to the multiple TS crossings observed by V2 is also discussed in this paper.

  16. Non-thermal electron acceleration in low Mach number collisionless shocks. I. Particle energy spectra and acceleration mechanism

    SciTech Connect

    Guo, Xinyi; Narayan, Ramesh; Sironi, Lorenzo

    2014-10-20

    Electron acceleration to non-thermal energies in low Mach number (M{sub s} ≲ 5) shocks is revealed by radio and X-ray observations of galaxy clusters and solar flares, but the electron acceleration mechanism remains poorly understood. Diffusive shock acceleration, also known as first-order Fermi acceleration, cannot be directly invoked to explain the acceleration of electrons. Rather, an additional mechanism is required to pre-accelerate the electrons from thermal to supra-thermal energies, so they can then participate in the Fermi process. In this work, we use two- and three-dimensional particle-in-cell plasma simulations to study electron acceleration in low Mach number shocks. We focus on the particle energy spectra and the acceleration mechanism in a reference run with M{sub s} = 3 and a quasi-perpendicular pre-shock magnetic field. We find that about 15% of the electrons can be efficiently accelerated, forming a non-thermal power-law tail in the energy spectrum with a slope of p ≅ 2.4. Initially, thermal electrons are energized at the shock front via shock drift acceleration (SDA). The accelerated electrons are then reflected back upstream where their interaction with the incoming flow generates magnetic waves. In turn, the waves scatter the electrons propagating upstream back toward the shock for further energization via SDA. In summary, the self-generated waves allow for repeated cycles of SDA, similarly to a sustained Fermi-like process. This mechanism offers a natural solution to the conflict between the bright radio synchrotron emission observed from the outskirts of galaxy clusters and the low electron acceleration efficiency usually expected in low Mach number shocks.

  17. Stochastic shock response spectrum decomposition method based on probabilistic definitions of temporal peak acceleration, spectral energy, and phase lag distributions of mechanical impact pyrotechnic shock test data

    NASA Astrophysics Data System (ADS)

    Hwang, James Ho-Jin; Duran, Adam

    2016-08-01

    Most of the times pyrotechnic shock design and test requirements for space systems are provided in Shock Response Spectrum (SRS) without the input time history. Since the SRS does not describe the input or the environment, a decomposition method is used to obtain the source time history. The main objective of this paper is to develop a decomposition method producing input time histories that can satisfy the SRS requirement based on the pyrotechnic shock test data measured from a mechanical impact test apparatus. At the heart of this decomposition method is the statistical representation of the pyrotechnic shock test data measured from the MIT Lincoln Laboratory (LL) designed Universal Pyrotechnic Shock Simulator (UPSS). Each pyrotechnic shock test data measured at the interface of a test unit has been analyzed to produce the temporal peak acceleration, Root Mean Square (RMS) acceleration, and the phase lag at each band center frequency. Maximum SRS of each filtered time history has been calculated to produce a relationship between the input and the response. Two new definitions are proposed as a result. The Peak Ratio (PR) is defined as the ratio between the maximum SRS and the temporal peak acceleration at each band center frequency. The ratio between the maximum SRS and the RMS acceleration is defined as the Energy Ratio (ER) at each band center frequency. Phase lag is estimated based on the time delay between the temporal peak acceleration at each band center frequency and the peak acceleration at the lowest band center frequency. This stochastic process has been applied to more than one hundred pyrotechnic shock test data to produce probabilistic definitions of the PR, ER, and the phase lag. The SRS is decomposed at each band center frequency using damped sinusoids with the PR and the decays obtained by matching the ER of the damped sinusoids to the ER of the test data. The final step in this stochastic SRS decomposition process is the Monte Carlo (MC

  18. Shock-Induced Melting of Maskelynite and the High-pressure Mineral Inventory of Shergottites: Implications to Evaluation of the Shock History of Martian Meteorites

    NASA Astrophysics Data System (ADS)

    El Goresy, A.

    2009-12-01

    Maskelynite [1-2] and the shock-induced melt pockets in shergottites are diagnostic features evidencing a major dynamic event on their parent body, Mars. Several models have been proposed for the origin of maskelynite: shock-induced solid-state vitrification of labradorite [3-4], metastable melting and quenching at high-pressure (high-P) [5], or ductile mobilization [4, 6]. Similarly, the origin and relevance of shock-melt pockets and veins as the main locations of high-P minerals in shergottites are controversial: localized formation by P-temperature (T) spikes in excess of 70-80 GPa [3, 4] or equilibrium assemblages evidencing peak-shock-P in the range of 25-35 GPa are discussed [7-10]. Crystallization ages are also controversial, with peaks at 160-190 Ma [11] and ≥ 4.1 Ga [12]: shock-induced age resetting may have been misinterpreted as igneous ages. We present ample evidence that maskelynite formed by metastable melting of plagioclase and quenching to glass at high-pressures as a result of the sluggishness of its inversion to lingunite. The direct consequence of our findings is the irrelevance of the refractive indices (RIs) of maskelynite as pressure indicators [3-4], since RIs were first established after decompression and quenching of maskelynite at its closure temperature of relaxation. We investigated the phase assemblages in Shergotty, Zagami, DAG 476, SAU 005, NWA 480, and NWA 856. Maskelynite contains the dense silica polymorph seifertite and the very dense monoclinic polymorph [8 -10]. Lingunite, CAS polymorph and Stishovite are present in shock-melt pockets [7-10]. Akimotoite, and silicate titanite were reported in shock-melt veins [13, 14]. The silicate liquids in which these dense minerals crystallized were perfect P-transmitting media, hence, contrary to [3-4], the dense minerals formed in equilibrium. The shock-induced events could be sequentially delineated commencing with the solid-state inversion to seifertite followed by pervasive melting of

  19. High-energy transients.

    PubMed

    Gehrels, Neil; Cannizzo, John K

    2013-06-13

    We present an overview of high-energy transients in astrophysics, highlighting important advances over the past 50 years. We begin with early discoveries of γ-ray transients, and then delve into physical details associated with a variety of phenomena. We discuss some of the unexpected transients found by Fermi and Swift, many of which are not easily classifiable or in some way challenge conventional wisdom. These objects are important insofar as they underscore the necessity of future, more detailed studies. PMID:23630376

  20. Very high energy colliders

    NASA Astrophysics Data System (ADS)

    Richter, B.

    1985-05-01

    The required emittance in very high energy machines are small. It will be a real challenge to produce these small emittances and to maintain them during acceleration. The small emittances probably make acceleration by laser techniques easier, if such techniques will be practical at all. The beam spot sizes are very small indeed. It will be a challenge to design beam transport systems with the necessary freedom from aberration required for these small spot sizes. It would of course help if the beta functions at the collision points could be reduced. Beam power will be large - to paraphrase the old saying, power is money - and efficient acceleration systems will be required.

  1. High energy electron cooling

    SciTech Connect

    Parkhomchuk, V.

    1997-09-01

    High energy electron cooling requires a very cold electron beam. The questions of using electron cooling with and without a magnetic field are presented for discussion at this workshop. The electron cooling method was suggested by G. Budker in the middle sixties. The original idea of the electron cooling was published in 1966. The design activities for the NAP-M project was started in November 1971 and the first run using a proton beam occurred in September 1973. The first experiment with both electron and proton beams was started in May 1974. In this experiment good result was achieved very close to theoretical prediction for a usual two component plasma heat exchange.

  2. An Investigation of High-Order Shock-Capturing Methods for Computational Aeroacoustics

    NASA Technical Reports Server (NTRS)

    Casper, Jay; Baysal, Oktay

    1997-01-01

    This project is motivated by the desire to develop numerical methods that will be useful in the study of compressible flows that exhibit aeroacoustic phenomena. Solutions to linear problems have been investigated through the development of a computer code based on the recent dispersion-relation-preserving (DRP) methodology. In regard to nonlinear problems, the class of essentially nonoscillatory (ENO) schemes have been considered as the primary candidates for solving aeroacoustic problems in which discontinuities are involved. Discontinuities in the solution itself (e.g. shocks) as well as in the geometry on which the problem is defined have been studied. Two-dimensional nonlinear problems were considered in order to determine if the one-dimensional results obtained in the first phase of this project were extendable to more realistic problems. Conclusions have been drawn in regard to the ability to numerically predict solutions of nonlinear problems with shocks to high-order accuracy.

  3. A high-speed, four-wavelength infrared pyrometer for low temperature shock physics experiments

    SciTech Connect

    Seifter, A.; Boboridis, K.; Payton, J. R.; Obst, A. W.

    2004-01-01

    In addition to the standard problems associated with contactless temperature measurements, pyrometry in shock physics experiments has many additional concerns. These include background temperatures which are often higher than the substrate temperature, non-uniform sample temperature due to hotspots and ejecta, fast sample motion up to several km s{sup -1}, fast-changing sample emissivity at shock breakout, and very short measurement times. We have designed a four channel, high speed near-infrared (NIR) pyrometer for measurements in the 400 to 1000K blackbody temperature regime. The front end optics are specific to each experiment, utilizing preferably reflective optics in order to mitigate spectral dispersion. Next-generation instruments under development are also discussed.

  4. On the simulation of shock-driven material mixing in high-Re flows (u)

    SciTech Connect

    Grinstein, Fernando F

    2009-01-01

    Implicit large eddy simulation proposes to effectively rely on the use of subgrid modeling and filtering provided implicitly by physics capturing numerics. Extensive work has demonstrated that predictive simulations of turbulent velocity fields are possible using a class of high resolution, non-oscillatory finite-volume (NFV) numerical algorithms. Truncation terms associated with NFV methods implicitly provide subgrid models capable of emulating the physical dynamics of the unresolved turbulent velocity fluctuations by themselves. The extension of the approach to the substantially more difficult problem of under-resolved material mixing by an under-resolved velocity field has not yet been investigated numerically, nor are there any theories as to when the methodology may be expected to be successful. Progress in addressing these issues in studies of shock-driven scalar mixing driven by Ritchmyer-Meshkov instabilities will be reported in the context of ongoing simulations of shock-tube laboratory experiments.

  5. Very High Pressure Single Pulse Shock Tube Studies of Aromatic Species

    SciTech Connect

    Brezinsky, K.

    2006-11-28

    The principal focus of this research program is aimed at understanding the oxidation and pyrolysis chemistry of primary aromatic molecules and radicals with the goal of developing a comprehensive kinetic model at conditions that are relevant to practical combustion devices. A very high pressure single pulse shock tube is used to obtain experimental data over a wide pressure range in the high pressure regime, 5-1000 bars, at pre-flame temperatures for fuel pyrolysis and oxidation over a broad spectrum of equivalence ratios. Stable species sampled from the shock tube are analyzed using standard chromatographic techniques using GC/MS-PDD and GC/TCD-FID. Experimental data from the HPST (stable species profiles) and data from other laboratories (if available) are simulated using kinetic models (if available) to develop a comprehensive model that can describe aromatics oxidation and pyrolysis over a wide range of experimental conditions. The shock tube has been heated (1000C) recently to minimize effects due to condensation of aromatic, polycyclic and other heavy species. Work during this grant period has focused on 7 main areas summarized in the final technical report.

  6. Type IIn supernovae as sources of high energy astrophysical neutrinos

    NASA Astrophysics Data System (ADS)

    Zirakashvili, V. N.; Ptuskin, V. S.

    2016-05-01

    It is shown that high-energy astrophysical neutrinos observed in the IceCube experiment can be produced by protons accelerated in extragalactic Type IIn supernova remnants by shocks propagating in the dense circumstellar medium. The nonlinear diffusive shock acceleration model is used for description of particle acceleration. We calculate the neutrino spectrum produced by an individual Type IIn supernova and the spectrum of neutrino background produced by IIn supernovae in the expanding Universe. We also found that the arrival direction of one Icecube neutrino candidate (track event 47) is at 1.35° from Type IIn supernova 2005bx.

  7. Effect of high-dose Ascorbic acid on vasopressor's requirement in septic shock

    PubMed Central

    Zabet, Mohadeseh Hosseini; Mohammadi, Mostafa; Ramezani, Masoud; Khalili, Hossein

    2016-01-01

    Objective: Effects of ascorbic acid on hemodynamic parameters of septic shock were evaluated in nonsurgical critically ill patients in limited previous studies. In this study, the effect of high-dose ascorbic acid on vasopressor drug requirement was evaluated in surgical critically ill patients with septic shock. Methods: Patients with septic shock who required a vasopressor drug to maintain mean arterial pressure >65 mmHg were assigned to receive either 25 mg/kg intravenous ascorbic acid every 6 h or matching placebo for 72 h. Vasopressor dose and duration were considered as the primary outcomes. Duration of Intensive Care Unit (ICU) stay and 28-day mortality has been defined as secondary outcomes. Findings: During the study period, 28 patients (14 in each group) completed the trial. Mean dose of norepinephrine during the study period (7.44 ± 3.65 vs. 13.79 ± 6.48 mcg/min, P = 0.004) and duration of norepinephrine administration (49.64 ± 25.67 vs. 71.57 ± 1.60 h, P = 0.007) were significantly lower in the ascorbic acid than the placebo group. No statistically significant difference was detected between the groups regarding the length of ICU stay. However, 28-day mortality was significantly lower in the ascorbic acid than the placebo group (14.28% vs. 64.28%, respectively; P = 0.009). Conclusion: High-dose ascorbic acid may be considered as an effective and safe adjuvant therapy in surgical critically ill patients with septic shock. The most effective dose of ascorbic acid and the best time for its administration should be determined in future studies. PMID:27162802

  8. Prospects at high energies

    SciTech Connect

    Quigg, C.

    1988-11-01

    I discuss some possibilities for neutrino experiments in the fixed-target environment of the SPS, Tevatron, and UNK, with their primary proton beams of 0.4, 0.9, and 3.0 TeV. The emphasis is on unfinished business: issues that have been recognized for some time, but not yet resolved. Then I turn to prospects for proton-proton colliders to explore the 1-TeV scale. I review the motivation for new physics in the neighborhood of 1 TeV and mention some discovery possibilities for high-energy, high-luminosity hadron colliders and the implications they would have for neutrino physics. I raise the possibility of the direct study of neutrino interactions in hadron colliders. I close with a report on the status of the SSC project. 38 refs., 17 figs.

  9. High-Order Energy Stable WENO Schemes

    NASA Technical Reports Server (NTRS)

    Yamaleev, Nail K.; Carpenter, Mark H.

    2008-01-01

    A new third-order Energy Stable Weighted Essentially NonOscillatory (ESWENO) finite difference scheme for scalar and vector linear hyperbolic equations with piecewise continuous initial conditions is developed. The new scheme is proven to be stable in the energy norm for both continuous and discontinuous solutions. In contrast to the existing high-resolution shock-capturing schemes, no assumption that the reconstruction should be total variation bounded (TVB) is explicitly required to prove stability of the new scheme. A rigorous truncation error analysis is presented showing that the accuracy of the 3rd-order ESWENO scheme is drastically improved if the tuning parameters of the weight functions satisfy certain criteria. Numerical results show that the new ESWENO scheme is stable and significantly outperforms the conventional third-order WENO finite difference scheme of Jiang and Shu in terms of accuracy, while providing essentially nonoscillatory solutions near strong discontinuities.

  10. A Statistical Hot Spot Reactive Flow Model for Shock Initiation and Detonation of Solid High Explosives

    SciTech Connect

    Nichols, A L; Tarver, C M

    2002-07-01

    A statistical hot spot reactive flow model for shock initiation and detonation of solid high explosives developed in the ALE3D hydrodynamic computer code is presented. This model is intended to evolve into a physically correct description of the physical and chemical mechanisms that control the onset of shock initiation via hotspot formation, the growth (01 failure to grow) of these hotspots into the surrounding explosive particles, the rapid transition to detonation, and self-sustaining detonation. Mesoscale modeling of the shock compression and temperature dependent chemical decomposition of individual explosive particles are currently yielding accurate predictions of hot spot formation and the subsequent growth (or failure) of these hotspot reactions in the surrounding grains. For two- and three-dimensional simulations of larger scale explosive charges, a statistical hotspot model that averages over thousands of individual hotspot dimensions and temperatures and then allows exothermic chemical reactions to grow (or fail to grow) due to thermal conduction is required. This paper outlines a first approach to constructing a probabilistic hot spot formulation based on the number density of potential hotspot sites. These hotspots can then either ignite or die out if they do not exceed certain ignition criteria, which are based on physical properties of the explosive particles. The growing hot spots spread at burn velocities given by experimentally determined deflagration velocity versus pressure relationships. The mathematics and assumptions involved in formulating the model and practical examples of its usefulness are given.

  11. A class of high resolution explicit and implicit shock-capturing methods

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1989-01-01

    An attempt is made to give a unified and generalized formulation of a class of high resolution, explicit and implicit shock capturing methods, and to illustrate their versatility in various steady and unsteady complex shock wave computations. Included is a systematic review of the basic design principle of the various related numerical methods. Special emphasis is on the construction of the basis nonlinear, spatially second and third order schemes for nonlinear scalar hyperbolic conservation laws and the methods of extending these nonlinear scalar schemes to nonlinear systems via the approximate Riemann solvers and the flux vector splitting approaches. Generalization of these methods to efficiently include equilibrium real gases and large systems of nonequilibrium flows are discussed. Some issues concerning the applicability of these methods that were designed for homogeneous hyperbolic conservation laws to problems containing stiff source terms and shock waves are also included. The performance of some of these schemes is illustrated by numerical examples for 1-, 2- and 3-dimensional gas dynamics problems.

  12. The microphysics of collisionless shock waves.

    PubMed

    Marcowith, A; Bret, A; Bykov, A; Dieckman, M E; Drury, L O'C; Lembège, B; Lemoine, M; Morlino, G; Murphy, G; Pelletier, G; Plotnikov, I; Reville, B; Riquelme, M; Sironi, L; Novo, A Stockem

    2016-04-01

    Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics. PMID:27007555

  13. The microphysics of collisionless shock waves

    NASA Astrophysics Data System (ADS)

    Marcowith, A.; Bret, A.; Bykov, A.; Dieckman, M. E.; O'C Drury, L.; Lembège, B.; Lemoine, M.; Morlino, G.; Murphy, G.; Pelletier, G.; Plotnikov, I.; Reville, B.; Riquelme, M.; Sironi, L.; Stockem Novo, A.

    2016-04-01

    Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

  14. High energy physics

    SciTech Connect

    Kernan, A.; Shen, B.C.; Ma, E.

    1997-07-01

    This proposal is for the continuation of the High Energy Physics program at the University of California at Riverside. In hadron collider physics the authors will complete their transition from experiment UA1 at CERN to the DZERO experiment at Fermilab. On experiment UA1 their effort will concentrate on data analysis at Riverside. At Fermilab they will coordinate the high voltage system for all detector elements. They will also carry out hardware/software development for the D0 muon detector. The TPC/Two-Gamma experiment has completed its present phase of data-taking after accumulating 160 pb{sup {minus}}1 of luminosity. The UC Riverside group will continue data and physics analysis and make minor hardware improvement for the high luminosity run. The UC Riverside group is participating in design and implementation of the data acquisition system for the OPAL experiment at LEP. Mechanical and electronics construction of the OPAL hadron calorimeter strip readout system is proceeding on schedule. Data analysis and Monte Carlo detector simulation efforts are proceeding in preparation for the first physics run when IEP operation comenses in fall 1989.

  15. Formation of downstream high-speed jets by a rippled nonstationary quasi-parallel shock: 2-D hybrid simulations

    NASA Astrophysics Data System (ADS)

    Hao, Y.; Lembege, B.; Lu, Q.; Guo, F.

    2016-03-01

    Experimental observations from space missions (including more recently Cluster and Time History of Events and Macroscale Interactions during Substorms data) have clearly revealed the existence of high-speed jets (HSJs) in the downstream region of the quasi-parallel terrestrial bow shock. Presently, two-dimensional hybrid simulations are performed in order to investigate the formation of such HSJs through a rippled quasi-parallel shock front. The simulation results show that (i) such shock fronts are strongly nonstationary along the shock normal, and (ii) ripples are evidenced along the shock front as the upstream ULF waves (excited by interaction between incident and reflected ions) are convected back to the front by the solar wind and contribute to the rippling formation. Then, these ripples are inherent structures of a quasi-parallel shock. As a consequence, new incident solar wind ions interact differently at different locations along the shock surface, and the ion bulk velocity strongly differs locally as ions are transmitted downstream. Preliminary results show that (i) local bursty patterns of turbulent magnetic field may form within the rippled front and play the role of local secondary shock; (ii) some incident ion flows penetrate the front, suffer some deflection (instead of being decelerated) at the locations of these secondary shocks, and are at the origin of well-structured (filamentary) HSJs downstream; and (iii) the spatial scales of HSJs are in a good agreement with experimental observations. Such downstream HSJs are shown to be generated by local curvature effects (front rippling) and the nonstationarity of the shock front itself.

  16. On the high Mach number shock structure singularity caused by overreach of Maxwellian molecules

    SciTech Connect

    Myong, R. S.

    2014-05-15

    The high Mach number shock structure singularity arising in moment equations of the Boltzmann equation was investigated. The source of the singularity is shown to be the unbalanced treatment between two high order kinematic and dissipation terms caused by the overreach of Maxwellian molecule assumption. In compressive gaseous flow, the high order stress-strain coupling term of quadratic nature will grow far faster than the strain term, resulting in an imbalance with the linear dissipation term and eventually a blow-up singularity in high thermal nonequilibrium. On the other hand, the singularity arising from unbalanced treatment does not occur in the case of velocity shear and expansion flows, since the high order effects are cancelled under the constraint of the free-molecular asymptotic behavior. As an alternative method to achieve the balanced treatment, Eu's generalized hydrodynamics, consistent with the second law of thermodynamics, was revisited. After introducing the canonical distribution function in exponential form and applying the cumulant expansion to the explicit calculation of the dissipation term, a natural platform suitable for the balanced treatment was derived. The resulting constitutive equation with the nonlinear factor was then shown to be well-posed for all regimes, effectively removing the high Mach number shock structure singularity.

  17. High Energy Astrophysics Mission

    NASA Technical Reports Server (NTRS)

    White, Nicholas E.; Ormes, Jonathan F. (Technical Monitor)

    2000-01-01

    The nature of gravity and its relationship to the other three forces and to quantum theory is one of the major challenges facing us as we begin the new century. In order to make progress we must challenge the current theories by observing the effects of gravity under the most extreme conditions possible. Black holes represent one extreme, where the laws of physics as we understand them break down. The Universe as whole is another extreme, where its evolution and fate is dominated by the gravitational influence of dark matter and the nature of the Cosmological constant. The early universe represents a third extreme, where it is thought that gravity may somehow be unified with the other forces. NASA's "Cosmic Journeys" program is part of a NASA/NSF/DoE tri-agency initiative designed to observe the extremes of gravity throughout the universe. This program will probe the nature of black holes, ultimately obtaining a direct image of the event horizon. It will investigate the large scale structure of the Universe to constrain the location and nature of dark matter and the nature of the cosmological constant. Finally it will search for and study the highest energy processes, that approach those found in the early universe. I will outline the High Energy Astrophysics part of this program.

  18. Predictive value of low tube voltage and dual-energy CT for successful shock wave lithotripsy: an in vitro study.

    PubMed

    Largo, Remo; Stolzmann, Paul; Fankhauser, Christian D; Poyet, Cédric; Wolfsgruber, Pirmin; Sulser, Tullio; Alkadhi, Hatem; Winklhofer, Sebastian

    2016-06-01

    This study investigates the capabilities of low tube voltage computed tomography (CT) and dual-energy CT (DECT) for predicting successful shock wave lithotripsy (SWL) of urinary stones in vitro. A total of 33 urinary calculi (six different chemical compositions; mean size 6 ± 3 mm) were scanned using a dual-source CT machine with single- (120 kVp) and dual-energy settings (80/150, 100/150 Sn kVp) resulting in six different datasets. The attenuation (Hounsfield Units) of calculi was measured on single-energy CT images and the dual-energy indices (DEIs) were calculated from DECT acquisitions. Calculi underwent SWL and the number of shock waves for successful disintegration was recorded. The prediction of required shock waves regarding stone attenuation/DEI was calculated using regression analysis (adjusted for stone size and composition) and the correlation between CT attenuation/DEI and the number of shock waves was assessed for all datasets. The median number of shock waves for successful stone disintegration was 72 (interquartile range 30-361). CT attenuation/DEI of stones was a significant, independent predictor (P < 0.01) for the number of required shock waves with the best prediction at 80 kVp (β estimate 0.576) (P < 0.05). Correlation coefficients between attenuation/DEI and the number of required shock waves ranged between ρ = 0.31 and 0.68 showing the best correlation at 80 kVp (P < 0.001). The attenuation of urinary stones at low tube voltage CT is the best predictor for successful stone disintegration, being independent of stone composition and size. DECT shows no added value for predicting the success of SWL. PMID:26391614

  19. [Mechanism of dwarfing effect of tomato (Solanum lycopersicon) seedlings induced by cold-shock treatment under high temperature stress].

    PubMed

    Li, Sheng-li; Bi, Ming-ming; Chen, Fei; Sun, Zhi-qiang

    2015-07-01

    To explore the dwarfing mechanism of tomato seedlings induced by cold-shock treatment followed by high temperature, tomato seedlings were subjected to cold-shock treatment once a day at 8:00 with temperature of 5, 10 and 15 °C for 10, 20 and 30 min, respectively, and ethylene production rate was measured. Plant height, ethylene production and gibberellin (GA3) content of the seedlings treated with T10 °C D10 min (cold-shock with 10 °C for 10 min), coupled with utilization of growth regulators, were also evaluated. The results showed that the release of ethylene was increased with the decrease of cold-shock temperature and extension of treatment time. The cold-shock treatment of 5 °C and 30 min had the highest ethylene production rate of 60.3 nL h-1 . g-1, which was 6.5 times of the control. None of ethephon (ETH), silver thiosulphate (STS), GA, or paclobutrazol (PP333) could completely block high ethylene production induced by cold-shock treatment. Tomato seedlings with cold-shock treatment (T10 °C D10 min ) resulted in reduction in GA3 content by 38.1% compared with the value of control (130.6 µg . g-1). Neither ethephon nor STS had significant effect on the dwarfing induced by cold-shock. However, GA3 weakened the dwarfing effect induced by cold-shock treatment (T10 °C D10 min), while PP333 greatly enhanced it. The dwarfing effect by cold-shock treatment of T10 °C D10 min was equivalent to that of application of 4.0 mg . L-1 PP333 based on the seedling height as an evaluation indicator. It was concluded that cold-shock treatment stimulated shoot ethylene production and blocked GA3 synthesis. GA3 played a vital role in dwarfing effect on tomato seedling induced by cold-shock treatment. Cold-shock with 10 °C and duration of 10 min could promote the growth of tomato seedlings with shorter stem and higher dry mass accumulation. PMID:26710633

  20. Highly Compressed Ion Beam for High Energy Density Science

    SciTech Connect

    Friedman, A.; Barnard, J.J.; Briggs, R.J.; Callahan, D.A.; Caporaso, G.J.; Celata, C.M.; Davidson, R.C.; Faltens, A.; Grisham, L.; Grote, D.P.; Henestroza, E.; Kaganovich I.; Lee, E.P.; Lee, R.W.; Leitner, M.; Logan, B.G.; Nelson, S.D.; Olson, C.L.; Penn, G.; Reginato,L.R.; Renk, T.; Rose, D.; Seessler, A.; Staples, J.W.; Tabak, M.; Thoma,C.; Waldron, W.; Welch, D.R.; Wurtele, J.; Yu, S.S.

    2005-05-16

    The Heavy Ion Fusion Virtual National Laboratory is developing the intense ion beams needed to drive matter to the High Energy Density regimes required for Inertial Fusion Energy and other applications. An interim goal is a facility for Warm Dense Matter studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach they are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target ''foils,'' which may in fact be foams with mean densities 1% to 10% of solid. This approach complements that being pursued at GSI Darmstadt, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrically target. They present the beam requirements for Warm Dense Matter experiments. The authors discuss neutralized drift compression and final focus experiments and modeling. They describe suitable accelerator architectures based on Drift-Tube Linac, RF, single-gap, Ionization-Front Accelerator, and Pulse-Line Ion Accelerator concepts. The last of these is being pursued experimentally. Finally, they discuss plans toward a user facility for target experiments.

  1. Ultrahigh energy cosmic rays as heavy nuclei from cluster accretion shocks

    NASA Astrophysics Data System (ADS)

    Inoue, Susumu; Sigl, Günter; Miniati, Francesco; et al.

    Large-scale accretion shocks around massive clusters of galaxies, generically expected in hierarchical scenarios of cosmological structure formation, are shown to be plausible sources of the observed ultrahigh energy cosmic rays (UHECRs) by accelerating a mixture of heavy nuclei including the iron group elements. Current observations can be explained if the source composition at injection for the heavier nuclei is somewhat enhanced from simple expectations for the accreting gas. The proposed picture should be clearly testable by current and upcoming facilities in the near future through characteristic features in the UHECR spectrum, composition and anisotropy, in particular the rapid increase of the average mass composition with energy from 1019 to 1020 eV. The associated X-ray and gamma-ray signatures are also briefly discussed.

  2. Vacuum high-harmonic generation in the shock regime and photon-photon scattering dynamics

    NASA Astrophysics Data System (ADS)

    King, B.; Böhl, P.; Ruhl, H.

    2016-02-01

    The presence of charged quantum virtual states permits a nonlinear self-interaction of the electromagnetic field in vacuum. This interaction can be described as real photon-photon scattering. This effect has been calculated for the case of colliding plane waves, when the centre- of-mass energy is much less than the electron rest energy. The quantum effect is included in the classical electromagnetic field equations of motion by a standard effective approach based upon a weak-field expansion of the Heisenberg-Euler Lagrangian. Solving for the resultant electromagnetic field indicates a signal for real photon-photon scattering when the plane waves overlap, which can be significantly larger than the usually-considered asymptotic values that reach detectors. By considering arbitrary numbers of four- and six-photon scattering, the process of vacuum higher harmonic generation has been studied both analytically and numerically. A route to prolific harmonic generation is identified that does not depend on field strengths being necessarily close to the Schwinger limit. The resulting vacuum electromagnetic shock wave has been studied and a nonlinear shock parameter identified.

  3. Modeling nonthermal emission from stellar bow shocks

    NASA Astrophysics Data System (ADS)

    Pereira, V.; López-Santiago, J.; Miceli, M.; Bonito, R.; de Castro, E.

    2016-04-01

    Context. Runaway O- and early B-type stars passing through the interstellar medium at supersonic velocities and characterized by strong stellar winds may produce bow shocks that can serve as particle acceleration sites. Previous theoretical models predict the production of high-energy photons by nonthermal radiative processes, but their efficiency is still debated. Aims: We aim to test and explain the possibility of emission from the bow shocks formed by runaway stars traveling through the interstellar medium by using previous theoretical models. Methods: We applied our model to AE Aurigae, the first reported star with an X-ray detected bow shock, to BD+43 3654, in which the observations failed in detecting high-energy emission, and to the transition phase of a supergiant star in the late stages of its life. Results: From our analysis, we confirm that the X-ray emission from the bow shock produced by AE Aurigae can be explained by inverse Compton processes involving the infrared photons of the heated dust. We also predict low high-energy flux emission from the bow shock produced by BD+43 3654, and the possibility of high-energy emission from the bow shock formed by a supergiant star during the transition phase from blue to red supergiant. Conclusions: Bow shocks formed by different types of runaway stars are revealed as a new possible source of high-energy photons in our neighborhood.

  4. Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber

    NASA Astrophysics Data System (ADS)

    Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

    2014-04-01

    Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

  5. High-energy emission from transients.

    PubMed

    Hinton, J A; Starling, R L C

    2013-06-13

    Cosmic explosions dissipate energy into their surroundings on a very wide range of time scales: producing shock waves and associated particle acceleration. The historical culprits for the acceleration of the bulk of Galactic cosmic rays are supernova remnants: explosions on approximately 10(4) year time scales. Increasingly, however, time-variable emission points to rapid and efficient particle acceleration in a range of different astrophysical systems. Gamma-ray bursts have the shortest time scales, with inferred bulk Lorentz factors of approximately 1000 and photons emitted beyond 100 GeV, but active galaxies, pulsar wind nebulae and colliding stellar winds are all now associated with time-variable emission at approximately teraelectron volt energies. Cosmic photons and neutrinos at these energies offer a powerful probe of the underlying physical mechanisms of cosmic explosions, and a tool for exploring fundamental physics with these systems. Here, we discuss the motivations for high-energy observations of transients, the current experimental situation, and the prospects for the next decade, with particular reference to the major next-generation high-energy observatory, the Cherenkov Telescope Array. PMID:23630380

  6. Laser shock compression of copper and copper-aluminum alloys: The slip to twinning transition in high-strain-rate deformation

    NASA Astrophysics Data System (ADS)

    Schneider, Matthew Scott

    Laser shock experiments are a relatively new approach to achieving extreme strain rates and pressures at time durations of nanoseconds. Copper and copper-aluminum alloys (2 and 6 weight percent) were subjected to laser pulses with durations of nanoseconds and energies between 70 J to 300 J. These conditions resulted in strain rates from 107--109 s -1 and pressures between 10--60 GPa. A quantitative, predictive understanding of plastic deformation (slip and twinning) and failure (void nucleation and growth) under these extreme regimes was developed through experiments, characterization and analysis. The mechanistic understanding this provided successfully incorporates effects of pressure, crystal orientation and stacking fault energy. There were four thrusts to this research: (1) Two orientations, [001] and [1¯34] were examined under various experimental conditions providing quantitative insight into the deformation behavior as a function of orientation, stacking-fault energy, and distance from impacted surface. Advanced characterization techniques were used to examine the lattice behavior and defects that form as a result of shock compression. The experimentally observed slip-twinning transition was quantified experimentally. (2) The formation of defects during the movement of the shock front through these specimens was analytically studied. Loop formation is explained in terms of thermal activation in shock loading. The dynamic yield strength at the shock front was determined by using data obtained by dynamic x-ray diffraction. Dislocation densities were calculated as a function of shock pressure and compared to experimentally obtained values. (3) The slip-twinning transition pressure was calculated using a modified Mechanical Threshold Stress (NITS) constitutive description and the Swegle-Grady equation relating pressure to strain rate. These analytical results were compared to the experimental results. Orientation, stacking fault energy, grain size, and

  7. High Shock, High Frequency Characteristics of a Mechanical Isolator for a Piezoresistive Accelerometer, the ENDEVCO 7270AM6*

    SciTech Connect

    BATEMAN,VESTA I.; BROWN,FREDERICK A.; NUSSER,MICHAEL A.

    2000-07-01

    A mechanical isolator has been developed for a piezoresistive accelerometer. The purpose of the isolator is to mitigate high frequency shocks before they reach the accelerometer because the high frequency shocks may cause the accelerometer to resonate. Since the accelerometer is undamped, it often breaks when it resonates. The mechanical isolator was developed in response to impact test requirements for a variety of structures at Sandia National Laboratories (SNL). An Extended Technical Assistance Program (ETAP) with the accelerometer manufacturer has resulted in a commercial mechanically isolated accelerometer that is available to the general public, the ENDEVCO 7270AM6*, for three shock acceleration ranges of 6,000 g, 20,000 g, and 60,000 g. The in-axis response shown in this report has acceptable frequency domain performance from DC to 10 kHz and 10(XO)over a temperature range of {minus}65 F to +185 F. Comparisons with other isolated accelerometers show that the ENDEVCO 7270AM6 has ten times the bandwidth of any other commercial isolator. ENDEVCO 7270AM6 cross-axis response is shown in this report.

  8. [Effects of cold-shock on the growth and flower bud differentiation of tomato seedlings under high temperature stress].

    PubMed

    Li, Sheng-li; Xia, Ya-zhen; Sun, Zhi-qiang

    2016-02-01

    In order to explore the effects of cold-shock on the growth and flower bud differentiation of tomato seedlings under high temperature, tomato seedlings were subjected to cold-shock treat- ments every day with 10 °C for 10 minutes in. an artificial climate chamber. Tomato seedlings were treated with cold-shock at the first true leaf stage and the treatment lasted for 15 days. Tomato seed- lings without cold-shock were used as control. At the fourth true leaf period of tomato seedlings, five plants were randomly sampled and the growth characteristics and the ultrastructure changes of meso- phyll cell of tomato seedlings were examined. The flower bud differentiation process of tomato seed- lings was observed at the periods of the second, fourth and sixth true leaves respectively. Flowering and fruiting of tomato seedlings were also investigated after transplanting. The results showed that the stem diameter and health index of tomato seedlings with cold-shock were enhanced by 7.2% and 55.5% compared with seedlings without cold-shock. Mesophyll cells of the seedlings with cold-shock arranged loosely and various organelles such as chloroplasts and mitochondria were morphologically integrated, while chloroplasts and mitochondria of seedlings mesophyll cells without cold-shock swelled up and thylakoids vacuolized apparently. The flower bud differentiation process of seedlings with cold-shock could be advanced significantly at the early seedling stage compared with the control and the advancement was weakened with the seedling growing. Fruit set number and percentage on the first and second inflorescence of tomato plants transplanted by seedlings with cold-shock were enhanced significantly compared with those of the control. These results indicated that the injury of membrane structure of various organelles, especially chloroplast and mitochondria could be allevia- ted by cold-shock treatment under high temperature tress. Cold-shock treatment could not only im- prove the

  9. The field-dependent shock profiles of a magnetorhelogical damper due to high impact: an experimental investigation

    NASA Astrophysics Data System (ADS)

    Kim, Hwan-Choong; Oh, Jong-Seok; Choi, Seung-Bok

    2015-02-01

    This work proposes a new damper featuring magnetorheological fluid (MR damper) and presents its field-dependent damping forces due to high impact. To achieve this goal, a large MR damper, which can produce a damping force of 100 kN at 6 A, is designed and manufactured based on the analysis of the magnetic flux intensity of the damper. After identifying the field-dependent damping force levels of the manufactured MR damper, a hydraulic horizontal shock tester is established. This shock testing system consists of a velocity generator, impact mass, shock programmer, and test mass. The MR damper is installed at the end of the wall in the shock tester and tested under four different experimental conditions. The shock profile characteristics of the MR damper due to different impact velocities are investigated at various input current levels. In addition, the inner pressure of the MR damper during impact, which depends on the input’s current level, is evaluated at two positions that can represent the pressure drop that generates the damping force of the MR damper. It is demonstrated from this impact testing that the shock profiles can be changed by the magnitude of the input current applied to the MR damper. It directly indicates that a desired shock profile can be achieved by installing the MR damper associated with appropriate control logics to adjust the magnitude of the input current.

  10. Purification of heat shock protein 90 from calf uterus and rat liver and characterization of the highly hydrophobic region.

    PubMed

    Iwasaki, M; Saito, H; Yamamoto, M; Korach, K S; Hirogome, T; Sugano, H

    1989-07-21

    Heat shock protein 90 was purified from calf uterus and rat liver. Both heat shock protein 90s had similar molecular weights, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, of Mr 87,000 and 88,000, isoelectric points of 5.2, and Stokes radii of 6.7 and 6.5 nm, respectively. Heat shock protein 90 bound to phenyl-Sepharose CL-4B even at low ionic strength, and also bound to butyl-Toyopearl at high ionic strength. Heat shock protein 90 bound to phenyl-Sepharose could be eluted with a buffer containing organic solvents or detergents such as 2-propanol, dioxane, dimethylformamide, methyl cellosolve, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate or Triton X-100, but not with ionic salts such as 1 M KCl. These results suggest that heat shock protein 90 possesses a significant hydrophobic region on the surface of the molecule. Hydrophobicities of heat shock protein 90 and 4S calf uterine estrogen receptor were both decreased by formation of a 8 S estrogen receptor complex. The role of the hydrophobic region of heat shock protein 90 in the interaction with estrogen receptor and other proteins is discussed. PMID:2752033

  11. Bromoform (CHBr sub 3 ) -- A very high-pressure shock-wave analyzer

    SciTech Connect

    McQueen, R.G.; Isaak, D.G.

    1989-01-01

    Bromoform, CHBr{sub 3}, appears to radiate like a black body. This means that the amount of radiation emitted from the shock front is extremely sensitive to temperature and hence even more sensitive to pressure. This feature has been exploited to locate overtake waves in impact experiments. Heretofore, Bromoform was used only for making timing measurements. However, if its P, V, E, and T EOS are known it could be used as high-pressure analyzer. Measurements to determine the Hugoniot, the Grueneisen parameter, {gamma}, and its optical radiation characterization are described, and preliminary data are presented. 8 refs., 7 figs., 1 tab.

  12. FSU High Energy Physics

    SciTech Connect

    Prosper, Harrison B.; Adams, Todd; Askew, Andrew; Berg, Bernd; Blessing, Susan K.; Okui, Takemichi; Owens, Joseph F.; Reina, Laura; Wahl, Horst D.

    2014-12-01

    The High Energy Physics group at Florida State University (FSU), which was established in 1958, is engaged in the study of the fundamental constituents of matter and the laws by which they interact. The group comprises theoretical and experimental physicists, who sometimes collaborate on projects of mutual interest. The report highlights the main recent achievements of the group. Significant, recent, achievements of the group’s theoretical physicists include progress in making precise predictions in the theory of the Higgs boson and its associated processes, and in the theoretical understanding of mathematical quantities called parton distribution functions that are related to the structure of composite particles such as the proton. These functions are needed to compare data from particle collisions, such as the proton-proton collisions at the CERN Large Hadron Collider (LHC), with theoretical predictions. The report also describes the progress in providing analogous functions for heavy nuclei, which find application in neutrino physics. The report highlights progress in understanding quantum field theory on a lattice of points in space and time (an area of study called lattice field theory), the progress in constructing several theories of potential new physics that can be tested at the LHC, and interesting new ideas in the theory of the inflationary expansion of the very early universe. The focus of the experimental physicists is the Compact Muon Solenoid (CMS) experiment at CERN. The report, however, also includes results from the D0 experiment at Fermilab to which the group made numerous contributions over a period of many years. The experimental group is particularly interested in looking for new physics at the LHC that may provide the necessary insight to extend the standard model (SM) of particle physics. Indeed, the search for new physics is the primary task of contemporary particle physics, one motivated by the need to explain certain facts, such as the

  13. A numerical study of fundamental shock noise mechanisms

    NASA Astrophysics Data System (ADS)

    Meadows, Kristine R.

    1995-05-01

    The results of this thesis demonstrate that direct numerical simulation can predict sound generation in unsteady aerodynamic flows containing shock waves. Shock waves can be significant sources of sound in high speed jet flows, on helicopter blades, and in supersonic combustion inlets. Direct computation of sound permits the prediction of noise levels in the preliminary design stage and can be used as a tool to focus experimental studies, thereby reducing cost and increasing the probability of a successfully quiet product in less time. This thesis reveals and investigates two mechanisms fundamental to sound generation by shocked flows: shock motion and shock deformation. Shock motion is modeled by the interaction of a sound wave with a shock. During the interaction, the shock wave begins to move and the sound pressure is amplified as the wave passes through the shock. The numerical approach presented in this thesis is validated by the comparison of results obtained in a quasi-one dimensional simulation with linear theory. Analysis of the perturbation energy demonstrated for the first time that acoustic energy is generated by the interaction. Shock deformation is investigated by the numerical simulation of a ring vortex interacting with a shock. This interaction models the passage of turbulent structures through the shock wave. The simulation demonstrates that both acoustic waves and contact surfaces are generated downstream during the interaction. Analysis demonstrates that the acoustic wave spreads cylindrically, that the sound intensity is highly directional, and that the sound pressure level increases significantly with increasing shock strength. The effect of shock strength on sound pressure level is consistent with experimental observations of shock noise, indicating that the interaction of a ring vortex with a shock wave correctly models a dominant mechanism of shock noise generation.

  14. High energy plasma accelerators

    SciTech Connect

    Tajima, T.

    1985-05-01

    Colinear intense laser beams ..omega../sub 0/, kappa/sub 0/ and ..omega../sub 1/, kappa/sub 1/ shone on a plasma with frequency separation equal to the electron plasma frequency ..omega../sub pe/ are capable of creating a coherent large longitudinal electric field E/sub L/ = mc ..omega../sub pe//e of the order of 1GeV/cm for a plasma density of 10/sup 18/ cm/sup -3/ through the laser beat excitation of plasma oscillations. Accompanying favorable and deleterious physical effects using this process for a high energy beat-wave accelerator are discussed: the longitudinal dephasing, pump depletion, the transverse laser diffraction, plasma turbulence effects, self-steepening, self-focusing, etc. The basic equation, the driven nonlinear Schroedinger equation, is derived to describe this system. Advanced accelerator concepts to overcome some of these problems are proposed, including the plasma fiber accelerator of various variations. An advanced laser architecture suitable for the beat-wave accelerator is suggested. Accelerator physics issues such as the luminosity are discussed. Applications of the present process to the current drive in a plasma and to the excitation of collective oscillations within nuclei are also discussed.

  15. High energy physics

    SciTech Connect

    Kernan, A.; Shen, B.C.; Ma, E.

    1997-07-01

    This proposal is for the continuation of the High Energy Physics Program at the University of California, Riverside. In 1990, we will concentrate on analysis of LEP data from the OPAL detector. We expect to record 10{sup 5} Z`s by the end of 1989 and 10{sup 6} in 1990. This data will be used to measure the number of quark-lepton families in the universe. In the second half of 1990 we will also be occupied with the installation of the D-Zero detector in the Tevatron Collider and the preparation of software for the 1991 run. A new initiative made possible by generous university support is a laboratory for detector development at UCR. The focus will be on silicon strip tracking detectors both for the D-Zero upgrade and for SSC physics. The theory program will pursue further various mass-generating radiative mechanisms for understanding small quark and lepton masses as well as some novel phenomenological aspects of supersymmetry.

  16. Assessment of Aerothermal Heating Augmentation Attributed to Surface Catalysis in High Enthalpy Shock Tunnel Flows

    NASA Astrophysics Data System (ADS)

    MacLean, M.; Holden, M.

    2009-01-01

    The effect of gas/surface interaction in making CFD predictions of convective heating has been considered with application to ground tests performed in high enthalpy shock tunnels where additional heating augmentation attributable to surface recombination has been observed for nitrogen, air and carbon dioxide flows. For test articles constructed of stainless steel and aluminum, measurements have been made with several types of heat transfer instrumentation including thin- film, calorimeter, and coaxial thermocouple sensors. These experiments have been modeled by computations made with the high quality, chemically reacting, Navier- Stokes solver, DPLR and the heating results compared. Some typical cases considered include results on an axisymmetric sphere-cone, axisymmetric spherical capsule, spherical capsule at angle of attack, and two- dimensional cylinder. In nitrogen flows, cases considered show a recombination probability on the order of 10-3, which agrees with published data. In many cases in air and CO2, measurements exceeding the predicted level of convective heating have been observed which are consistent with approximately complete recombination (to O2/N2 or CO2) on the surface of the model (sometimes called a super-catalytic wall). It has been recognized that the conclusion that this behavior is tied to an excessively high degree of catalytic efficiency is dependent on the current understanding of the freestream and shock-layer state of the gas.

  17. Thermal Shock Behavior of Single Crystal Oxide Refractive Concentrators for High Temperatures Solar Thermal Propulsion

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Choi, Sung R.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium-aluminum-garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) have been considered as refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermal mechanical reliability of the oxide components in severe thermal environments during space mission sun/shade transitions is of great concern. In this paper, critical mechanical properties of these oxide crystals are determined by the indentation technique. Thermal shock resistance of the oxides is evaluated using a high power CO, laser under high temperature-high thermal gradients. Thermal stress fracture behavior and failure mechanisms of these oxide materials are investigated under various temperature and heating conditions.

  18. Diffusive Shock Acceleration

    NASA Astrophysics Data System (ADS)

    Baring, Matthew

    2003-04-01

    The process of diffusive acceleration of charged particles in shocked plasmas is widely invoked in astrophysics to account for the ubiquitous presence of signatures of non-thermal relativistic electrons and ions in the universe. This statistical energization mechanism, manifested in turbulent media, was first posited by Enrico Fermi in 1949 to explain the observed cosmic ray population, which exhibits an almost power-law distribution in rigidity. The absence of a momentum scale is a key characteristic of diffusive shock acceleration, and astrophysical systems generally only impose scales at the injection (low energy) and loss (high energy) ends of the particle spectrum. The existence of structure in the cosmic ray spectrum (the "knee") at around 3000 TeV has promoted contentions that there are at least two origins for cosmic rays, a galactic one supplying those up to the knee, and perhaps an extragalactic one that can explain even the ultra-high energy cosmic rays (UHECRs) seen at 1-300 EeV. Accounting for the UHECRs with familiar astrophysical sites of acceleration has historically proven difficult due to the need to assume high magnetic fields in order to reduce the shortest diffusive acceleration timescale, the ion gyroperiod, to meaningful values. Yet active galaxies and gamma-ray bursts remain strong and interesting candidate sources for UHECRs, turning the theoretical focus to relativistic shocks. This review summarizes properties of diffusive shock acceleration that are salient to the issue of UHECR generation. These include spectral indices, anisotropies, acceleration efficencies and timescales, as functions of the shock speed and mean field orientation, and also the degree of field turbulence. Astrophysical sites for UHECR production are also critiqued.

  19. Diffusive shock acceleration in the presence of current sheets

    NASA Technical Reports Server (NTRS)

    Kota, J.; Jokipii, J. R.

    1994-01-01

    We study the nature of diffusive shock acceleration in the presence of current sheets which are oriented normal to the shock, so that the drift along the sheets carries particles either away from or toward the shock plane. We consider a system with periodic regions of alternating magnetic field direction. This can be taken to be a very crude representation of the termination of the solar wind, with the equator being one sheet and the pole, with its rapid opposite drift, being another. We find very important effects of the current sheets. For example, particle intensities at the shock will be enhanced near one sheet and depressed at the other. Furthermore, the intensity at high energies (averaged over the shock plane) may in fact be considerably larger than in the standard one-dimensional infinite shock case. Implications of these results for the possible acceleration of cosmic electrons up to high energies at the solar-wind termination shock will briefly be discussed.

  20. Design and control of a high velocity, high force hydraulic shock test machine

    NASA Astrophysics Data System (ADS)

    Favour, J. D.

    1986-04-01

    This paper discusses the design and control of a large hydraulic shock testing device. The system is capable of peak velocities up to 10.2 m/s (400 in/sec) and peak forces up to 801 kN (180,000 lbs). The major challenges discussed are: (1) the concept design, (2) the specification and procurement of two very large (2500 gpm) electrohydraulic servovalves and (3) the failsafe control of the servovalves and system response. The system performance is briefly discussed.

  1. High Energy Density Capacitors

    SciTech Connect

    2010-07-01

    BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.

  2. Perspectives on high-energy-density physicsa)

    NASA Astrophysics Data System (ADS)

    Drake, R. P.

    2009-05-01

    Much of 21st century plasma physics will involve work to produce, understand, control, and exploit very nontraditional plasmas. High-energy-density (HED) plasmas are often examples, variously involving strong Coulomb interactions and ≪1 particles per Debye sphere, dominant radiation effects, and strongly relativistic or strongly quantum-mechanical behavior. Indeed, these and other modern plasma systems often fall outside the early standard theoretical definitions of "plasma." Here the specific ways in which HED plasmas differ from traditional plasmas are discussed. This is first done by comparison of important physical quantities across the parameter regime accessible by existing or contemplated experimental facilities. A specific discussion of some illustrative cases follows, including strongly radiative shocks and the production of relativistic, quasimonoenergetic beams of accelerated electrons.

  3. A Seeman-Bohlin geometry for high-resolution nanosecond x-ray diffraction measurements from shocked polycrystalline and amorphous materials

    NASA Astrophysics Data System (ADS)

    Milathianaki, D.; Hawreliak, J.; McNaney, J. M.; El-Dasher, B. S.; Saculla, M. D.; Swift, D. C.; Lorenzana, H. E.; Ditmire, T.

    2009-09-01

    We report on a focusing x-ray diffraction geometry capable of high-resolution in situ lattice probing from dynamically loaded polycrystalline and amorphous materials. The Seeman-Bohlin-type camera presented here is ideally suited for time-resolved x-ray diffraction measurements performed on high energy multibeam laser platforms. Diffraction from several lattice planes of ablatively shock-loaded 25 μm thick Cu foils was recorded on a focusing circle of diameter D =100 mm with exceptional angular resolution limited only by the spectral broadening of the x-ray source. Excellent agreement was found between the density measured using x-ray diffraction and that inferred from Doppler velocimetry and the known shock Hugoniot of Cu. In addition, x-ray diffraction signal was captured from an amorphous material under static conditions.

  4. A Seeman-Bohlin geometry for high-resolution nanosecond x-ray diffraction measurements from shocked polycrystalline and amorphous materials.

    PubMed

    Milathianaki, D; Hawreliak, J; McNaney, J M; El-Dasher, B S; Saculla, M D; Swift, D C; Lorenzana, H E; Ditmire, T

    2009-09-01

    We report on a focusing x-ray diffraction geometry capable of high-resolution in situ lattice probing from dynamically loaded polycrystalline and amorphous materials. The Seeman-Bohlin-type camera presented here is ideally suited for time-resolved x-ray diffraction measurements performed on high energy multibeam laser platforms. Diffraction from several lattice planes of ablatively shock-loaded 25 mum thick Cu foils was recorded on a focusing circle of diameter D=100 mm with exceptional angular resolution limited only by the spectral broadening of the x-ray source. Excellent agreement was found between the density measured using x-ray diffraction and that inferred from Doppler velocimetry and the known shock Hugoniot of Cu. In addition, x-ray diffraction signal was captured from an amorphous material under static conditions. PMID:19791950

  5. A Seeman-Bohlin geometry for high-resolution nanosecond x-ray diffraction measurements from shocked polycrystalline and amorphous materials

    SciTech Connect

    Milathianaki, D.; Hawreliak, J.; McNaney, J. M.; El-Dasher, B. S.; Saculla, M. D.; Swift, D. C.; Lorenzana, H. E.; Ditmire, T.

    2009-09-15

    We report on a focusing x-ray diffraction geometry capable of high-resolution in situ lattice probing from dynamically loaded polycrystalline and amorphous materials. The Seeman-Bohlin-type camera presented here is ideally suited for time-resolved x-ray diffraction measurements performed on high energy multibeam laser platforms. Diffraction from several lattice planes of ablatively shock-loaded 25 {mu}m thick Cu foils was recorded on a focusing circle of diameter D=100 mm with exceptional angular resolution limited only by the spectral broadening of the x-ray source. Excellent agreement was found between the density measured using x-ray diffraction and that inferred from Doppler velocimetry and the known shock Hugoniot of Cu. In addition, x-ray diffraction signal was captured from an amorphous material under static conditions.

  6. Individual contributions of friction and impact on non-shock initiation of high explosives

    NASA Astrophysics Data System (ADS)

    Peterson, Paul; Avilucea, Gabe; Bishop, Robert; Sanchez, John

    2007-06-01

    Throughout the years a variety of tests have been designed which provide insight into the sensitivity of high explosives (HE) to non-shock initiation. Various standard tests such as the LANL drop weight impact, LLNL drop hammer, drop tower and skid tests have been developed to measure energetic response of explosives subjected to a combination of friction and oblique impact. In addition, the BAM test (for HE powders on roughened ceramic) and ABL friction test (powders or solids on roughened metal) have been developed for testing HE under frictional loading. In an effort to understand first principles of non-shock initiation, we have designed a series of tests to try to isolate friction and impact during the insult of HE. An initial series of tests have been completed with PETN, HMX, and as-pressed pellets of PBX 9501 (95 wt. percent HMX, 5 wt. percent inert binder), PBX 9502 (95 wt. percent TATB, wt. percent inert binder), Cyclotol (75 wt. percent RDX/25, wt. percent TNT), and Comp B3 (60 wt. percent RDX, 40 wt. percent TNT). The results suggest that some types of high explosives are relatively insensitive to pure impact and pure friction but relatively sensitive to insults involving a combination of impact and friction.

  7. Individual Contributions of Friction and Impact on Non-Shock Initiation of High Explosives

    NASA Astrophysics Data System (ADS)

    Peterson, P. D.; Avilucea, G. R.; Bishop, R. L.; Sanchez, J. A.

    2007-12-01

    Throughout the years a variety of tests have been designed which provide insight into the sensitivity of high explosives (HE) to non-shock initiation. Various standard tests such as the LANL drop weight impact, LLNL drop hammer, drop tower and skid tests have been developed to measure energetic response of explosives subjected to a combination of friction and oblique impact. In addition, the BAM test (for HE powders on roughened ceramic) and ABL friction test (powders or solids on roughened metal) have been developed for testing HE under frictional loading. In an effort to understand first principles of non-shock initiation, we have designed a series of tests to try to isolate friction and impact during the insult of HE. An initial series of tests have been completed with PETN, HMX, and as-pressed pellets of PBX 9501 (95 wt% HMX, wt% inert binder), PBX 9502 (95 wt% TATB, 5 wt% inert binder), Cyclotol (75 wt% RDX/25, wt% TNT), and Comp B3 (60 wt% RDX, 40 wt% TNT). The results suggest that some types of high explosives are relatively insensitive to pure impact and pure friction but relatively sensitive to insults involving a combination of impact and friction.

  8. Operation of the ISL transonic shock tube in a high subsonic flow regime

    NASA Astrophysics Data System (ADS)

    Seiler, F.; Havermann, M.; Boller, F.; Mangold, P.; Takayama, K.

    The transonic flow regime plays an important role in experimental aerodynamic research. Modern civil aircraft fly up to a Mach number of M ≈ 0.9 in the high subsonic speed regime, as, for example, the Boeing or Airbus passenger aircraft. Nearly sonic Mach numbers are foreseen for innovative airplane concepts like the sonic cruiser by Boeing. In the military domain, guided missiles like the cruise missile also fly in the high subsonic flow regime. For testing purposes, transonic wind tunnels are mainly used for sub- as well as supersonic design applications. These wind tunnels have normally very large dimensions, which makes their operation quite expensive. If only small scale tests are required, a cheap working facility turns out to be more beneficial. For this purpose, a conventional shock tube operated at transonic flow conditions has been put into operation at the ISL. In the transonic flow regime, however, the reduction of the tube cross section by the model can produce severe distortions followed by a choking of the shock tube flow in the test section. Extensive experimental investigations were performed to determine the subsonic choking Mach number as a function of the model size. These results are compared with theoretical estimations and, more in detail, with CFD calculations.

  9. A high-frequency first-principle model of a shock absorber and servo-hydraulic tester

    NASA Astrophysics Data System (ADS)

    Czop, Piotr; SŁawik, Damian

    2011-08-01

    The aim of this paper is to present the model of a complete system, consisting of a variable damping shock absorber and a specialized servo-hydraulic tester, used to evaluate the vibration levels produced by a shock absorber. This kind of evaluation is used within the automotive industry to investigate shock absorbers, as an alternative to vehicle-level tests. The purpose of such testing is to quantify a shock absorber's ability to transfer the mid- and high-frequency content of the vibrations passing from the road profile, through the suspension, to the vehicle body. The first-principle non-linear model formulated, derived and validated in this paper allows laboratory test conditions to be reproduced. It also provides an understanding of structural vibrations in regard to the dynamical interactions between the shock absorber, its basic components (e.g. valve systems), mounting elements, and the hydraulic actuator. The model is capable of capturing important dynamical properties over a wide operating range, yet is only moderately complex. The model has proved to be qualitatively suitable and quantitatively accurate based on validation work performed for the entire frequency range of interest, i.e. 0-700 Hz. The application scope of this study covers the engineering need to develop a simulation tool for high-frequency shock absorber design optimization.

  10. Can a dual-energy computed tomography predict unsuitable stone components for extracorporeal shock wave lithotripsy?

    PubMed Central

    Ahn, Sung Hoon; Oh, Tae Hoon

    2015-01-01

    Purpose To assess the potential of dual-energy computed tomography (DECT) to identify urinary stone components, particularly uric acid and calcium oxalate monohydrate, which are unsuitable for extracorporeal shock wave lithotripsy (ESWL). Materials and Methods This clinical study included 246 patients who underwent removal of urinary stones and an analysis of stone components between November 2009 and August 2013. All patients received preoperative DECT using two energy values (80 kVp and 140 kVp). Hounsfield units (HU) were measured and matched to the stone component. Results Significant differences in HU values were observed between uric acid and nonuric acid stones at the 80 and 140 kVp energy values (p<0.001). All uric acid stones were red on color-coded DECT images, whereas 96.3% of the nonuric acid stones were blue. Patients with calcium oxalate stones were divided into two groups according to the amount of monohydrate (calcium oxalate monohydrate group: monohydrate≥90%, calcium oxalate dihydrate group: monohydrate<90%). Significant differences in HU values were detected between the two groups at both energy values (p<0.001). Conclusions DECT improved the characterization of urinary stone components and was a useful method for identifying uric acid and calcium oxalate monohydrate stones, which are unsuitable for ESWL. PMID:26366277

  11. Anomalous Transport of High Energy Cosmic Rays in Galactic Superbubbles

    NASA Technical Reports Server (NTRS)

    Barghouty, Nasser F.

    2014-01-01

    High-energy cosmic rays may exhibit anomalous transport as they traverse and are accelerated by a collection of supernovae explosions in a galactic superbubble. Signatures of this anomalous transport can show up in the particles' evolution and their spectra. In a continuous-time-random- walk (CTRW) model assuming standard diffusive shock acceleration theory (DSA) for each shock encounter, and where the superbubble (an OB stars association) is idealized as a heterogeneous region of particle sources and sinks, acceleration and transport in the superbubble can be shown to be sub-diffusive. While the sub-diffusive transport can be attributed to the stochastic nature of the acceleration time according to DSA theory, the spectral break appears to be an artifact of transport in a finite medium. These CTRW simulations point to a new and intriguing phenomenon associated with the statistical nature of collective acceleration of high energy cosmic rays in galactic superbubbles.

  12. Collisionless Weibel shocks: Full formation mechanism and timing

    SciTech Connect

    Bret, A.; Stockem, A.; Narayan, R.; Silva, L. O.

    2014-07-15

    Collisionless shocks in plasmas play an important role in space physics (Earth's bow shock) and astrophysics (supernova remnants, relativistic jets, gamma-ray bursts, high energy cosmic rays). While the formation of a fluid shock through the steepening of a large amplitude sound wave has been understood for long, there is currently no detailed picture of the mechanism responsible for the formation of a collisionless shock. We unravel the physical mechanism at work and show that an electromagnetic Weibel shock always forms when two relativistic collisionless, initially unmagnetized, plasma shells encounter. The predicted shock formation time is in good agreement with 2D and 3D particle-in-cell simulations of counterstreaming pair plasmas. By predicting the shock formation time, experimental setups aiming at producing such shocks can be optimised to favourable conditions.

  13. Shock wave reflection induced detonation (SWRID) under high pressure and temperature condition in closed cylinder

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Qi, Y.; Liu, H.; Zhang, P.; He, X.; Wang, J.

    2016-07-01

    Super-knock is one of the major obstacles for improving power density in advanced internal combustion engines (ICE). This work studied the mechanism of super-knock initiation using a rapid compression machine that simulated conditions relevant to ICEs and provided excellent optical accessibility. Based on the high-speed images and pressure traces of the stoichiometric iso-octane/oxygen/nitrogen combustion under high-temperature and high-pressure conditions, it was observed that detonation was first initiated in the near-wall region as a result of shock wave reflection. Before detonation was initiated, the speed of the combustion wave front was less than that of the Chapman-Jouguet (C-J) detonation speed (around 1840 m/s). In the immediate vicinity of the initiation, the detonation speed was much higher than that of the C-J detonation.

  14. Radio-Loud Coronal Mass Ejections without Shocks near Earth

    NASA Astrophysics Data System (ADS)

    Akiyama, S.; Gopalswamy, N.; Xie, H.; Yashiro, S.; Makela, P. A.; St Cyr, O. C.; MacDowall, R. J.; Kaiser, M. L.

    2010-12-01

    Type II radio bursts are produced by low energy electrons accelerated in shocks driven by coronal mass ejections (CMEs). One can infer shocks near the Sun, in the Interplanetary medium, and near Earth depending on the wavelength range in which the type II bursts are produced. In fact, type II bursts are good indicators of CMEs that produce solar energetic particles. If the type II burst occurs from a source on the Earth-facing side of the solar disk, it is highly likely that a shock arrives at Earth in 2-3 days and hence can be used to predict shock arrival at Earth. However, a significant fraction of CMEs producing type II bursts were not associated shocks at Earth, even though the CMEs originated close to the disk center. There are several reasons for the lack of shock at 1 AU. CMEs originating at large central meridian distances (CMDs) may be driving a shock, but the shock may not be extended sufficiently to reach to the Sun-Earth line. Another possibility is CME cannibalism because of which shocks merge and one observes a single shock at Earth. Finally, the CME-driven shock may become weak and dissipate before reaching 1 AU. We examined a set of 30 type II bursts observed by the Wind/WAVES experiment that had the solar sources very close to the disk center (within a CMD of 15 degrees), but did not have shock at Earth. We find that the near-Sun speeds of the associated CMEs average to ~600 km/s, only slightly higher than the average speed of CMEs associated with radio-quiet shocks. However, the fraction of halo CMEs is only ~28%, compared to 40% for radio-quiet shocks and 72% for all radio-loud shocks. We conclude that the disk-center radio loud CMEs with no shocks at 1 AU are generally of lower energy and they drive shocks only close to the Sun.

  15. Terrestrial Effects of High Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Atri, Dimitra

    2011-01-01

    On geological timescales, the Earth is likely to be exposed to an increased flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. These high-energy particles strike the Earth's atmosphere initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles. Increased ionization could lead to changes in atmospheric chemistry, resulting in ozone depletion. This could increase the flux of solar UVB radiation at the surface, which is potentially harmful to living organisms. Increased ionization affects the global electrical circuit can could possibly enhance the low-altitude cloud formation rate. Secondary particles such as muons and thermal neutrons produced as a result of nuclear interactions are able to reach the ground, enhancing the biological radiation dose. The muon flux dominates radiation dose from cosmic rays causing DNA damage and increase in the mutation rates, which can have serious biological implications for terrestrial and sub-terrestrial life. This radiation dose is an important constraint on the habitability of a planet. Using CORSIKA, we perform massive computer simulations and construct lookup tables from 10 GeV - 1 PeV primaries (1 PeV - 0.1 ZeV in progress), which can be used to quantify these effects. These tables are freely available to the community and can be used for other studies, not necessarily relevant to Astrobiology. We use these tables to study the terrestrial implications of galactic shock generated by the infall of our galaxy toward the Virgo cluster. This could be a possible mechanism explaining the observed periodicity in biodiversity in paleobiology databases.

  16. Terrestrial effects of high energy cosmic rays

    NASA Astrophysics Data System (ADS)

    Atri, Dimitra

    On geological timescales, the Earth is likely to be exposed to higher than the usual flux of high energy cosmic rays (HECRs) from astrophysical sources such as nearby supernovae, gamma ray bursts or by galactic shocks. These high-energy particles strike the Earth's atmosphere, initiating an extensive air shower. As the air shower propagates deeper, it ionizes the atmosphere by producing charged secondary particles and photons. Increased ionization leads to changes in atmospheric chemistry, resulting in ozone depletion. This increases the flux of solar UVB radiation at the surface, which is potentially harmful to living organisms. Increased ionization affects the global electrical circuit, which could enhance the low-altitude cloud formation rate. Secondary particles such as muons and thermal neutrons produced as a result of hadronic interactions of the primary cosmic rays with the atmosphere are able to reach the ground, enhancing the biological radiation dose. The muon flux dominates the radiation dose from cosmic rays causing damage to DNA and an increase in mutation rates and cancer, which can have serious biological implications for surface and sub-surface life. Using CORSIKA, we perform massive computer simulations and construct lookup tables for 10 GeV - 1 PeV primaries, which can be used to quantify these effects from enhanced cosmic ray exposure to any astrophysical source. These tables are freely available to the community and can be used for other studies. We use these tables to study the terrestrial implications of galactic shock generated by the infall of our galaxy toward the Virgo cluster. Increased radiation dose from muons could be a possible mechanism explaining the observed periodicity in biodiversity in paleobiology databases.

  17. High Order Numerical Methods for LES of Turbulent Flows with Shocks

    NASA Technical Reports Server (NTRS)

    Kotov, D. V.; Yee, H. C.; Hadjadj, A.; Wray, A.; Sjögreen, B.

    2014-01-01

    Simulation of turbulent flows with shocks employing explicit subgrid-scale (SGS) filtering may encounter a loss of accuracy in the vicinity of a shock. In this work we perform a comparative study of different approaches to reduce this loss of accuracy within the framework of the dynamic Germano SGS model. One of the possible approaches is to apply Harten's subcell resolution procedure to locate and sharpen the shock, and to use a one-sided test filter at the grid points adjacent to the exact shock location. The other considered approach is local disabling of the SGS terms in the vicinity of the shock location. In this study we use a canonical shock-turbulence interaction problem for comparison of the considered modifications of the SGS filtering procedure. For the considered test case both approaches show a similar improvement in the accuracy near the shock.

  18. High Energy Density Physics on LULI2000 Laser Facility

    NASA Astrophysics Data System (ADS)

    Koenig, M.; Benuzzi-Mounaix, A.; Ozaki, N.; Ravasio, A.; Vinci, T.; Lepape, S.; Tanaka, K.; Riley, D.

    2006-07-01

    We present here a summary of some High Density Energy Physics experiments performed on the new facility LULI 2000. First, different flyer plate targets scheme have been tested loading shock in fused-quartz plate. Temperature data along the Hugoniot curve have been obtained. Second, a strongly coupled and degenerated Aluminium plasma has been probed by X-ray Thomson scattering. Compton shift from electrons has been observed in various density conditions.

  19. 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.

  20. Chondrule Destruction in Nebular Shocks

    NASA Astrophysics Data System (ADS)

    Jacquet, Emmanuel; Thompson, Christopher

    2014-12-01

    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 epsilon >~ 0.1, and possibly even for solar abundances because of "sandblasting" by finer dust. A flow with epsilon >~ 10 requires much smaller shock velocities (~2 versus 8 km s-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. High Energy Colliders

    NASA Astrophysics Data System (ADS)

    Palmer, R. B.; Gallardo, J. C.

    INTRODUCTION PHYSICS CONSIDERATIONS GENERAL REQUIRED LUMINOSITY FOR LEPTON COLLIDERS THE EFFECTIVE PHYSICS ENERGIES OF HADRON COLLIDERS HADRON-HADRON MACHINES LUMINOSITY SIZE AND COST CIRCULAR e^{+}e^- MACHINES LUMINOSITY SIZE AND COST e^{+}e^- LINEAR COLLIDERS LUMINOSITY CONVENTIONAL RF SUPERCONDUCTING RF AT HIGHER ENERGIES γ - γ COLLIDERS μ ^{+} μ^- COLLIDERS ADVANTAGES AND DISADVANTAGES DESIGN STUDIES STATUS AND REQUIRED R AND D COMPARISION OF MACHINES CONCLUSIONS DISCUSSION

  2. High-energy gamma-rays from GRB X-ray flares

    SciTech Connect

    Wang, X. Y.; Li, Z.; Meszaros, P.

    2007-07-12

    The recent detection of X-ray flares during the afterglow phase of gamma-ray bursts (GRBs) suggests an inner-engine origin, at radii inside the forward shock. There must be inverse Compton (IC) emission arising from such flare photons scattered by forward shock afterglow electrons when they are passing through the forward shock. We find that this IC emission produces high energy gamma-ray flares, which may be detected by AGILE, GLAST and ground-based TeV telescopes. The anisotropic IC scattering between flare photons and forward shock electrons does not affect the total IC component intensity, but cause a time delay of the IC component peak relative to the flare peak. We speculate that this IC component may already have been detected by EGRET from a very strong burst--GRB940217. Future observations by GLAST may help to distinguish whether X-ray flares originate from late central engine activity or from external shocks.

  3. Explicit and implicit compact high-resolution shock-capturing methods for multidimensional Euler equations 1: Formulation

    NASA Technical Reports Server (NTRS)

    Yee, H. C.

    1995-01-01

    Two classes of explicit compact high-resolution shock-capturing methods for the multidimensional compressible Euler equations for fluid dynamics are constructed. Some of these schemes can be fourth-order accurate away from discontinuities. For the semi-discrete case their shock-capturing properties are of the total variation diminishing (TVD), total variation bounded (TVB), total variation diminishing in the mean (TVDM), essentially nonoscillatory (ENO), or positive type of scheme for 1-D scalar hyperbolic conservation laws and are positive schemes in more than one dimension. These fourth-order schemes require the same grid stencil as their second-order non-compact cousins. One class does not require the standard matrix inversion or a special numerical boundary condition treatment associated with typical compact schemes. Due to the construction, these schemes can be viewed as approximations to genuinely multidimensional schemes in the sense that they might produce less distortion in spherical type shocks and are more accurate in vortex type flows than schemes based purely on one-dimensional extensions. However, one class has a more desirable high-resolution shock-capturing property and a smaller operation count in 3-D than the other class. The extension of these schemes to coupled nonlinear systems can be accomplished using the Roe approximate Riemann solver, the generalized Steger and Warming flux-vector splitting or the van Leer type flux-vector splitting. Modification to existing high-resolution second- or third-order non-compact shock-capturing computer codes is minimal. High-resolution shock-capturing properties can also be achieved via a variant of the second-order Lax-Friedrichs numerical flux without the use of Riemann solvers for coupled nonlinear systems with comparable operations count to their classical shock-capturing counterparts. The simplest extension to viscous flows can be achieved by using the standard fourth-order compact or non-compact formula

  4. Annular arc accelerator shock tube

    NASA Technical Reports Server (NTRS)

    Leibowitz, L. P. (Inventor)

    1976-01-01

    An annular arc accelerator shock tube employs a cold gas driver to flow a stream of gas from an expansion section through a high voltage electrode section to a test section, thus driving a shock wave in front of it. A glow discharge detects the shock wave and actuates a trigger generator which in turn fires spark-gap switches to discharge a bank of capacitors across a centered cathode and an annular anode in tandem electrode sections. The initial shock wave passes through the anode section from the cathode section thereby depositing energy into the flow gas without the necessity of any diaphragm opening in the gas flow from the expansion section through the electrode sections.

  5. Numerical simulation by TVD schemes of complex shock reflections from airfoils at high angle of attack. [Total Variation Diminishing

    NASA Technical Reports Server (NTRS)

    Moon, Young J.; Yee, H. C.

    1987-01-01

    The shock-capturing capability of total variation diminishing (TVD) schemes is demonstrated for a more realistic complex shock-diffraction problem for which the experimental data are available. Second-order explicit upwind and symmetric TVD schemes are used to solve the time-dependent Euler equations of gas dynamics for the interaction of a blast wave with an airfoil at high angle-of-attack. The test cases considered are a time-dependent moving curved-shock wave and a contant moving planar-shock wave impinging at an angle-of-attack 30 deg on a NACA 0018 airfoil. Good agreement is obtained between isopycnic contours computed by the TVD schemes and those from experimental interferograms. No drastic difference in flow-field structure is found between the curved- and planar-shock wave cases, except for a difference in density level near the lower surface of the airfoil. Computation for cases with higher shock Mach numbers is also possible. Numerical experiments show that the symmetric TVD scheme is less sensitive to the boundary conditions treatment than the upwind scheme.

  6. On the hyperbolic nature of the equations of alluvial river hydraulics and the equivalence of stable and energy dissipating shocks

    NASA Astrophysics Data System (ADS)

    Zanraea, D. D. L.; Needham, D. J.

    The depth-averaged hydraulic equations augmented with a suitable bed-load sediment transport function form a closed system which governs the one-dimensional flow in an alluvial river or channel. In this paper, it is shown that this system is hyperbolic and yields three families of shock-wave solutions. These are determined to be temporally stable in restricted regions of the (H, F0)-plane, via the Lax shock inequalities. Further, it is demonstrated that this criterion is equivalent to the energy dissipation criterion developed by Needham and Hey (1991).

  7. An Energy-Based Limit State Function for Estimation of Structural Reliability in Shock Environments

    DOE PAGESBeta

    Guthrie, Michael A.

    2013-01-01

    limit state function is developed for the estimation of structural reliability in shock environments. This limit state function uses peak modal strain energies to characterize environmental severity and modal strain energies at failure to characterize the structural capacity. The Hasofer-Lind reliability index is briefly reviewed and its computation for the energy-based limit state function is discussed. Applications to two degree of freedom mass-spring systems and to a simple finite element model are considered. For these examples, computation of the reliability index requires little effort beyond a modal analysis, but still accounts for relevant uncertainties in both the structure and environment.more » For both examples, the reliability index is observed to agree well with the results of Monte Carlo analysis. In situations where fast, qualitative comparison of several candidate designs is required, the reliability index based on the proposed limit state function provides an attractive metric which can be used to compare and control reliability.« less

  8. Ion acoustic shock and solitary waves in highly relativistic plasmas with nonextensive electrons and positrons

    NASA Astrophysics Data System (ADS)

    Hafez, M. G.; Talukder, M. R.; Hossain Ali, M.

    2016-01-01

    The Korteweg-de Vries Burgers (KdVB) -like equation is derived to study the characteristics of nonlinear propagation of ion acoustic solitions in a highly relativistic plasma containing relativistic ions and nonextensive distribution of electrons and positrons using the well known reductive perturbation technique. The KdVB-like equation is solved employing the Bernoulli's equation method taking unperturbed positron to electron concentration ratio, electron to positron temperature ratio, strength of nonextensivity, ion kinematic viscosity, and highly relativistic streaming factor. It is found that these parameters significantly modify the structures of the solitonic excitation. The ion acoustic shock profiles are observed due to the influence of ion kinematic viscosity. In the absence of dissipative term to the KdVB equation, compressive and rarefactive solitons are observed in case of superthermality, but only compressive solitons are found for the case of subthermality.

  9. Spiral Density Wave Shock-induced Star Formation at High Galactic Latitudes.

    PubMed

    Martos; Allen; Franco; Kurtz

    1999-12-01

    We have modeled the gas response to a spiral density wave (SDW) in a thick, magnetized galactic disk. The inclusion in the model of the vertically extended galactic warm ionized gas layer alters the conventional view of the SDW scenario for star formation: whereas marked density enhancements still occur in the midplane, the shock and a prominent high column density structure extend to high z (the height above the galactic midplane) above the arm. We argue that if the SDW mechanism indeed triggers molecular cloud and star formation, it should do so not only at the midplane but also at distances well above the star-forming thin disk of the conventional picture. The resulting structure resembles a hydraulic jump, or bore, in which gas entering the spiral arm rises suddenly on the upstream side of the arm, then accelerates and angles downward, finally landing on a large downfall region downstream of the arm. PMID:10550285

  10. Computational study of 3-D hot-spot initiation in shocked insensitive high-explosive

    NASA Astrophysics Data System (ADS)

    Najjar, F. M.; Howard, W. M.; Fried, L. E.; Manaa, M. R.; Nichols, A., III; Levesque, G.

    2012-03-01

    High-explosive (HE) material consists of large-sized grains with micron-sized embedded impurities and pores. Under various mechanical/thermal insults, these pores collapse generating hightemperature regions leading to ignition. A hydrodynamic study has been performed to investigate the mechanisms of pore collapse and hot spot initiation in TATB crystals, employing a multiphysics code, ALE3D, coupled to the chemistry module, Cheetah. This computational study includes reactive dynamics. Two-dimensional high-resolution large-scale meso-scale simulations have been performed. The parameter space is systematically studied by considering various shock strengths, pore diameters and multiple pore configurations. Preliminary 3-D simulations are undertaken to quantify the 3-D dynamics.

  11. Acceleration of positrons in supernova shocks

    NASA Technical Reports Server (NTRS)

    Ellison, Donald C.

    1992-01-01

    During this project we investigated the acceleration of leptons (electrons and positrons) in collisionless shock waves. In particular, we were interested in how leptons are accelerated in the blast waves existing in the remnants of supernova explosions. Supernova remnants (SNRs) have long been considered as the most likely source of galactic cosmic rays but no definite connection between SNRs and the cosmic rays seen at earth can be made. Only by understanding lepton acceleration in shocks can the rich SNR data base be properly used to understand cosmic ray origins. Our project was directed at the neglected aspects of lepton acceleration. We showed that the efficiency of lepton acceleration depended critically on the lepton injection energy. We showed that, even when infection effects are not important, that proton and lepton distribution functions produced by shocks are quite different in the critical energy range for producing the observed synchrotron emission. We also showed that transrelativistic effects produced proton spectra that were not in agreement with standard results from radio observations, but that the lepton spectra were, in fact, consistent with observations. We performed simulations of relativistic shocks (shocks where the flow speed is a sizable fraction of the speed of light) and discovered some interesting effects. We first demonstrated the power of the Monte Carlo technique by determining the shock jump conditions in relativistic shocks. We then proceeded to determine how relativistic shocks accelerate particles. We found that nonlinear relativistic shocks treat protons and leptons even more differently than nonrelativistic shocks. The transrelativistic effects on the shock structure from the heavy ion component reduces the lepton acceleration to a tiny fraction of the ion acceleration. This effect is dramatic even if high energy leptons (many times thermal energy) are injected, and was totally unexpected. Our results have important

  12. A high angiopoietin-2/angiopoietin-1 ratio is associated with a high risk of septic shock in patients with febrile neutropenia

    PubMed Central

    2013-01-01

    Introduction Endothelial barrier breakdown is a hallmark of septic shock, and proteins that physiologically regulate endothelial barrier integrity are emerging as promising biomarkers of septic shock development. Patients with cancer and febrile neutropenia (FN) present a higher risk of sepsis complications, such as septic shock. Nonetheless, these patients are normally excluded or under-represented in sepsis biomarker studies. The aim of our study was to validate the measurement of a panel of microvascular permeability modulators as biomarkers of septic shock development in cancer patients with chemotherapy-associated FN. Methods This was a prospective study of diagnostic accuracy, performed in two distinct in-patient units of a university hospital. Levels of vascular endothelial growth factor A (VEGF-A), soluble fms-like tyrosine kinase-1 (sFlt-1) and angiopoietin (Ang) 1 and 2 were measured after the onset of neutropenic fever, in conditions designed to mimic the real-world use of a sepsis biomarker, based on our local practice. Patients were categorized based on the development of septic shock by 28 days as an outcome. Results A total of 99 consecutive patients were evaluated in the study, of which 20 developed septic shock and 79 were classified as non-complicated FN. VEGF-A and sFlt-1 levels were similar between both outcome groups. In contrast, Ang-2 concentrations were increased in patients with septic shock, whereas an inverse finding was observed for Ang-1, resulting in a higher Ang-2/Ang-1 ratio in patients with septic shock (5.29, range 0.58 to 57.14) compared to non-complicated FN (1.99, range 0.06 to 64.62; P = 0.01). After multivariate analysis, the Ang-2/Ang-1 ratio remained an independent factor for septic shock development and 28-day mortality. Conclusions A high Ang-2/Ang-1 ratio can predict the development of septic shock in cancer patients with febrile neutropenia. PMID:23915833

  13. Impact angle control of interplanetary shock geoeffectiveness: A statistical study

    NASA Astrophysics Data System (ADS)

    Oliveira, Denny M.; Raeder, Joachim

    2015-06-01

    We present a survey of interplanetary (IP) shocks using Wind and ACE satellite data from January 1995 to December 2013 to study how IP shock geoeffectiveness is controlled by IP shock impact angles. A shock list covering one and a half solar cycle is compiled. The yearly number of IP shocks is found to correlate well with the monthly sunspot number. We use data from SuperMAG, a large chain with more than 300 geomagnetic stations, to study geoeffectiveness triggered by IP shocks. The SuperMAG SML index, an enhanced version of the familiar AL index, is used in our statistical analysis. The jumps of the SML index triggered by IP shock impacts on the Earth's magnetosphere are investigated in terms of IP shock orientation and speed. We find that, in general, strong (high speed) and almost frontal (small impact angle) shocks are more geoeffective than inclined shocks with low speed. The strongest correlation (correlation coefficient R = 0.78) occurs for fixed IP shock speed and for varied IP shock impact angle. We attribute this result, predicted previously with simulations, to the fact that frontal shocks compress the magnetosphere symmetrically from all sides, which is a favorable condition for the release of magnetic energy stored in the magnetotail, which in turn can produce moderate to strong auroral substorms, which are then observed by ground-based magnetometers.

  14. Flare physics at high energies

    NASA Technical Reports Server (NTRS)

    Ramaty, R.

    1990-01-01

    High-energy processes, involving a rich variety of accelerated particle phenomena, lie at the core of the solar flare problem. The most direct manifestation of these processes are high-energy radiations, gamma rays, hard X-rays and neutrons, as well as the accelerated particles themselves, which can be detected in interplanetary space. In the study of astrophysics from the moon, the understanding of these processes should have great importance. The inner solar system environment is strongly influenced by activity on the sun; the physics of solar flares is of great intrinsic interest; and much high-energy astrophysics can be learned from investigations of flare physics at high energies.

  15. Measurement of High-Pressure Shock Waves in Cryogenic Deuterium-Tritium Ice Layered Capsule Implosions on NIF

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Moody, J. D.; Celliers, P. M.; Ross, J. S.; Ralph, J.; Le Pape, S.; Berzak Hopkins, L.; Parham, T.; Sater, J.; Mapoles, E. R.; Holunga, D. M.; Walters, C. F.; Haid, B. J.; Kozioziemski, B. J.; Dylla-Spears, R. J.; Krauter, K. G.; Frieders, G.; Ross, G.; Bowers, M. W.; Strozzi, D. J.; Yoxall, B. E.; Hamza, A. V.; Dzenitis, B.; Bhandarkar, S. D.; Young, B.; Van Wonterghem, B. M.; Atherton, L. J.; Landen, O. L.; Edwards, M. J.; Boehly, T. R.

    2013-08-01

    The first measurements of multiple, high-pressure shock waves in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility have been performed. The strength and relative timing of these shocks must be adjusted to very high precision in order to keep the DT fuel entropy low and compressibility high. All previous measurements of shock timing in inertial confinement fusion implosions [T. R. Boehly et al., Phys. Rev. Lett. 106, 195005 (2011), H. F. Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] have been performed in surrogate targets, where the solid DT ice shell and central DT gas regions were replaced with a continuous liquid deuterium (D2) fill. This report presents the first experimental validation of the assumptions underlying this surrogate technique.

  16. Measurement of high-pressure shock waves in cryogenic deuterium-tritium ice layered capsule implosions on NIF.

    PubMed

    Robey, H F; Moody, J D; Celliers, P M; Ross, J S; Ralph, J; Le Pape, S; Berzak Hopkins, L; Parham, T; Sater, J; Mapoles, E R; Holunga, D M; Walters, C F; Haid, B J; Kozioziemski, B J; Dylla-Spears, R J; Krauter, K G; Frieders, G; Ross, G; Bowers, M W; Strozzi, D J; Yoxall, B E; Hamza, A V; Dzenitis, B; Bhandarkar, S D; Young, B; Van Wonterghem, B M; Atherton, L J; Landen, O L; Edwards, M J; Boehly, T R

    2013-08-01

    The first measurements of multiple, high-pressure shock waves in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility have been performed. The strength and relative timing of these shocks must be adjusted to very high precision in order to keep the DT fuel entropy low and compressibility high. All previous measurements of shock timing in inertial confinement fusion implosions [T. R. Boehly et al., Phys. Rev. Lett. 106, 195005 (2011), H. F. Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] have been performed in surrogate targets, where the solid DT ice shell and central DT gas regions were replaced with a continuous liquid deuterium (D2) fill. This report presents the first experimental validation of the assumptions underlying this surrogate technique. PMID:23971581

  17. High-energy neutrinos from active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Done, C.; Salamon, M. H.; Sommers, P.

    1991-01-01

    The spectrum and high-energy neutrino background flux from photomeson production in active galactic nuclei (AGN) is calculated using the recent UV and X-ray observations to define the photon fields and an accretion-disk shock-acceleration model for producing high-energy particles. Collectively, AGN produce the dominant isotropic neutrino background between 10,000 and 10 to the 10th GeV, detectable with current instruments. AGN neutrinos should produce a sphere of stellar disruption which may explain the 'broad-line region' seen in AGN.

  18. Laboratory Astrophysics: Study of Radiative Shocks

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

    Radiative shocks are high Mach number shocks with a strong coupling between radiation and hydrodynamics which leads to a structure governed by a radiative precursor. They might be encountered in various astrophysical systems: stellar accretion shocks, pulsating stars, interaction of supernovae with the intestellar medium etc. A numerical one dimensional (1D) stationary study of the coupling between hydrodynamics and radiative transfer is being performed. An estimate of the error made by the 1D approach in the radiative transfer treatment is done by an approximate short characteristics approach. It shows, for exemple, how much of the radiation escapes from the medium in the configuration of the experiment. The experimental study of these shocks has been performed with the high energy density laser of the LULI, at the École Polytechnique (France). We have observed several shocks identified as radiative shocks. The shock waves propagate at about 50 km/s in a tiny 10 mm3 shock tube filled with gaz. From the measurements, it is possible to infer several features of the shock such as the speed and the electronic density.

  19. The influence of the energy emitted by solar flare soft X-ray bursts on the propagation of their associated interplanetary shock waves

    NASA Technical Reports Server (NTRS)

    Pinter, S.; Dryer, M.

    1985-01-01

    The relationship between the thermal energy released from 29 solar flares and the propagation features of their associated interplanetary shock waves that were detected at 1 AU is investigated. The 29 interplanetary shock waves were identified unambiguously and their tracking from each solar flare was deduced by tracking their associated interplanetary type-II radio emission. The thermal energy released in the solar flares was estimated from the time-intensity profiles of 1-8 A soft X-ray bursts from each flare. A good relationship is found between the flares' thermal energy with the IP shock-waves' transient velocity and arrival time at the earth - that is, the largest flare energy released is associated with the faster shock waves. Finally, a possible scenario of formation of a shock wave during the early phase of the flare and its propagation features is discussed.

  20. The series elastic shock absorber: tendon elasticity modulates energy dissipation by muscle during burst deceleration

    PubMed Central

    Konow, Nicolai; Roberts, Thomas J.

    2015-01-01

    During downhill running, manoeuvring, negotiation of obstacles and landings from a jump, mechanical energy is dissipated via active lengthening of limb muscles. Tendon compliance provides a ‘shock-absorber’ mechanism that rapidly absorbs mechanical energy and releases it more slowly as the recoil of the tendon does work to stretch muscle fascicles. By lowering the rate of muscular energy dissipation, tendon compliance likely reduces the risk of muscle injury that can result from rapid and forceful muscle lengthening. Here, we examine how muscle–tendon mechanics are modulated in response to changes in demand for energy dissipation. We measured lateral gastrocnemius (LG) muscle activity, force and fascicle length, as well as leg joint kinematics and ground-reaction force, as turkeys performed drop-landings from three heights (0.5–1.5 m centre-of-mass elevation). Negative work by the LG muscle–tendon unit during landing increased with drop height, mainly owing to greater muscle recruitment and force as drop height increased. Although muscle strain did not increase with landing height, ankle flexion increased owing to increased tendon strain at higher muscle forces. Measurements of the length–tension relationship of the muscle indicated that the muscle reached peak force at shorter and likely safer operating lengths as drop height increased. Our results indicate that tendon compliance is important to the modulation of energy dissipation by active muscle with changes in demand and may provide a mechanism for rapid adjustment of function during deceleration tasks of unpredictable intensity. PMID:25716796

  1. Observation of Shock-Induced Phases of Nb2O5 Single Crystal under High-Resolution Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Kikuchi, Masae; Kusaba, Keiji; Bannai, Eisuke; Fukuoka, Kiyoto; Syono, Yasuhiko; Hiraga, Kenji

    1985-12-01

    Shock-loading experiments on Nb2O5 single crystals were carried out up to 54 GPa by the gun method. The shock-loaded materials are recovered by using both closed and open recovery fixtures and were examined by powder X-ray diffraction analysis and high-resolution electron microscopy. Complete conversion to T-Nb2O5 of μm size, denser by 12% than H-Nb2O5, was found in the pressure range from 20-40 GPa. When single-crystal H-Nb2O5 was shocked perpendicular to the b-axis using the open-system recovery fixture, an unidentified phase referred to as the X-phase, besides T-Nb2O5 and shock-reduced NbxO2 with the rutile structure, was observed. The high-resolution image of the X-phase is interpreted as two-dimensionally disordered H-Nb2O5. The X-phase is probably formed in the rapid decompression process from the shock-induced high-pressure phase.

  2. [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

  3. Frontiers in plasma science: a high energy density perspective

    NASA Astrophysics Data System (ADS)

    Remington, Bruce

    2015-11-01

    The potential for ground-breaking research in plasma physics in high energy density (HED) regimes is compelling. The combination of HED facilities around the world spanning microjoules to megajoules, with time scales ranging from femtoseconds to microseconds enables new regimes of plasma science to be experimentally probed. The ability to shock and ramp compress samples and simultaneously probe them allows dense, strongly coupled, Fermi degenerate plasmas relevant to planetary interiors to be studied. Shock driven hydrodynamic instabilities evolving into turbulent flows relevant to the dynamics of exploding stars are being probed. The physics and dynamics of magnetized plasmas relevant to astrophysics and inertial confinement fusion are also starting to be studied. High temperature, high velocity interacting flows are being probed for evidence of astrophysical collisionless shock formation. Turbulent, high magnetic Reynolds number flows are being experimentally generated to look for evidence of the turbulent magnetic dynamo effect. And new results from thermonuclear reactions in dense hot plasmas relevant to stellar interiors are starting to emerge. A selection of examples providing a compelling vision for frontier plasma science in the coming decade will be presented. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  4. High energy forming facility

    NASA Technical Reports Server (NTRS)

    Ciurlionis, B.

    1967-01-01

    Watertight, high-explosive forming facility, 25 feet in diameter and 15 feet deep, withstands repeated explosions of 10 pounds of TNT equivalent. The shell is fabricated of high strength steel and allows various structural elements to deform or move elastically and independently while retaining structural integrity.

  5. High energy nuclear collisions

    SciTech Connect

    Plasil, F.

    1998-01-01

    This presentation covers three broad topics: a brief introduction to the field of nucleus-nucleus collisions at relativistic energies; a discussion of several topics illustrating what`s been learned after more than a decade of fixed target experiments; and an indication of what the future may bring at the Relativistic Heavy Ion Collider (RHIC) under construction at the Brookhaven National Laboratory (BNL) and at the Large Hadron Collider (LHC) planned at CERN.

  6. High-energy Neutrinos from Sources in Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Fang, Ke; Olinto, Angela V.

    2016-09-01

    High-energy cosmic rays can be accelerated in clusters of galaxies, by mega-parsec scale shocks induced by the accretion of gas during the formation of large-scale structures, or by powerful sources harbored in clusters. Once accelerated, the highest energy particles leave the cluster via almost rectilinear trajectories, while lower energy ones can be confined by the cluster magnetic field up to cosmological time and interact with the intracluster gas. Using a realistic model of the baryon distribution and the turbulent magnetic field in clusters, we studied the propagation and hadronic interaction of high-energy protons in the intracluster medium. We report the cumulative cosmic-ray and neutrino spectra generated by galaxy clusters, including embedded sources, and demonstrate that clusters can contribute a significant fraction of the observed IceCube neutrinos above 30 TeV while remaining undetected in high-energy cosmic rays and γ rays for reasonable choices of parameters and source scenarios.

  7. Dynamic compaction of high-temperature superconducting YBa2Cu3O(x) powders by laser-driven shocks

    NASA Astrophysics Data System (ADS)

    Darquey, P.; Kieffer, J. C.; Gauthier, J.; Pepin, H.; Chaker, M.; Champagne, B.; Villeneuve, D.; Baldis, H.

    1991-10-01

    Laser-driven shocks are successfully used to density high-temperature superconducting YBa2Cu3O7 ceramic powders. Pressures of 10 GPa on a nanosecond time scale were generated by producing a confined plasma with a high-intensity laser pulse. Significant consolidation is generated up to 300 microns below the irradiated surface. Magnetic susceptibility measurements indicate that the pinning of the intergranular vortices is strongly affected by the shock propagation. Recovery of superconductivity in compacted material is obtained with a postshock oxygen annealing.

  8. Oblique propagation of ion acoustic shock waves in weakly and highly relativistic plasmas with nonthermal electrons and positrons

    NASA Astrophysics Data System (ADS)

    Hafez, M. G.; Roy, N. C.; Talukder, M. R.; Hossain Ali, M.

    2016-09-01

    This work investigates the oblique nonlinear propagation of ion acoustic (IA) shock waves for both weakly and highly relativistic plasmas composed of nonthermal electrons and positrons with relativistic thermal ions. The KdVB-like equation, involving dispersive, weakly transverse dispersive, nonlinearity and dissipative coefficients, is derived employing the well known reductive perturbation method. The integration of this equation is carried out by the {tanh} method taking the stable shock formation condition into account. The effects of nonthermal electrons and positrons, nonthermal electrons with isothermal positrons, isothermal electrons with nonthermal positrons, and isothermal electrons and positrons on oblique propagation of IA shock waves in weakly relativistic regime are described. Furthermore, the effects of plasma parameters on oblique propagation of IA shock waves in highly relativistic regime are discussed and compared with weakly relativistic case. It is seen that the plasma parameters within certain limits significantly modify the structures of the IA shock waves in both cases. The results may be useful for better understanding of the interactions of charged particles with extra-galactic jets as well as astrophysical compact objects.

  9. Gamma Rays from Intergalactic Shocks

    NASA Astrophysics Data System (ADS)

    Keshet, Uri; Waxman, Eli; Loeb, Abraham; Springel, Volker; Hernquist, Lars

    2003-03-01

    Structure formation in the intergalactic medium (IGM) produces large-scale, collisionless shock waves, in which electrons can be accelerated to highly relativistic energies. Such electrons can Compton-scatter cosmic microwave background photons up to γ-ray energies. We study the radiation emitted in this process using a hydrodynamic cosmological simulation of a ΛCDM universe. The resulting radiation, extending beyond TeV energies, has roughly constant energy flux per decade in photon energy, in agreement with the predictions of Loeb & Waxman. Assuming that a fraction ξe=0.05 of the shock thermal energy is transferred to the population of accelerated relativistic electrons, as inferred from collisionless nonrelativistic shocks in the interstellar medium, we find that the energy flux of this radiation, ɛ2(dJ/dɛ)~=50-160 eV cm-2 s-1 sr-1, constitutes ~10% of the extragalactic γ-ray background flux. The associated γ-ray point sources are too faint to account for the ~60 unidentified EGRET γ-ray sources, but GLAST should detect and resolve several γ-ray sources associated with large-scale IGM structures for ξe~=0.03 and many more sources for larger ξe. The intergalactic origin of the shock-induced radiation can be verified through a cross-correlation with, e.g., the galaxy distribution that traces the same structure. Its shock origin may be tested by cross-correlating its properties with radio synchrotron radiation, emitted as the same accelerated electrons gyrate in postshock magnetic fields. We predict that GLAST and Cerenkov telescopes such as MAGIC, VERITAS, and HESS should resolve γ-rays from nearby (redshifts z<~0.01) rich galaxy clusters, perhaps in the form of a ~5-10 Mpc diameter ringlike emission tracing the cluster accretion shock, with luminous peaks where the ring intersects galaxy filaments detectable even at z~=0.025.

  10. 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.

  11. The microphysics of collisionless shocks

    NASA Astrophysics Data System (ADS)

    Wilson, Lynn Bruce, III

    2010-11-01

    Shock waves in interplanetary (IP) space are of considerable interest due to their potential to damage ground based electronic systems and their ability to energize charged particles. The energization of charged particles at IP shocks has the obvious extrapolation to supernova shock waves, which are thought to be a candidate for generating the most energetic particles in the universe. The observations and theory behind collisionless shock wave evolution suggest that IP shocks should, for the most part, be stable structures which require energy dissipation. In a regular fluid, like our atmosphere, energy dissipation is accomplished through binary particle collisions transferring the loss of bulk flow kinetic energy to heat. Plasmas are mostly collisionless fluids, thus requiring other means by which to dissipate energy. The studies herein were performed using wave and particle data primarily from the Wind spacecraft to investigate the microphysics of IP shock energy dissipation mechanisms. Due to their lower Mach numbers, more simplified geometry, and quasi-perpendicular nature, IP shock waves are an excellent laboratory to study wave-particle related dissipation mechanisms. Utilization of multiple data sets from multiple high time resolution instruments on board the Wind spacecraft, we have performed studies on the transition region microphysics of IP shocks. The work began with a statistical study of high frequency (≥ 1 kHz) waveform capture data during 67 IP shocks with Mach numbers ranging from ∼1-6 found ion-acoustic wave amplitudes correlated with the fast mode Mach number and shock strength. The ion-acoustic waves (IAWs) were estimated to produce anomalous resistivities roughly seven orders of magnitude above classical estimates. Another study was an examination of low frequency waves (0.25 Hz < f < 10 Hz) at five quasi-perpendicular IP shocks found the wave modes to be consistent with oblique precusor whistler waves at four of the events. The strongest

  12. Experimental Study Of Metallurgical Evolutions In Metallic Alloys Induced By Laser Generated High Pressure Shocks

    NASA Astrophysics Data System (ADS)

    Fabbro, R.; Fournier, J.; Fabre, E.; Leberichel, E.; Hannau, Th; Corbet, C.

    1986-11-01

    Some preliminary results are presented concerning the damages and the evolutions of metallurgical properties of Fe-C alloys induced by laser shock waves at two different laser wavelengths. In the present work, changes induced by laser shocking have been measured : pressure, microhardness, residual stresses. In addition microstructural variations at the surface and in depth have been observed.

  13. Molecular mechanisms of the angiogenic effects of low-energy shock wave therapy: roles of mechanotransduction.

    PubMed

    Hatanaka, Kazuaki; Ito, Kenta; Shindo, Tomohiko; Kagaya, Yuta; Ogata, Tsuyoshi; Eguchi, Kumiko; Kurosawa, Ryo; Shimokawa, Hiroaki

    2016-09-01

    We have previously demonstrated that low-energy extracorporeal cardiac shock wave (SW) therapy improves myocardial ischemia through enhanced myocardial angiogenesis in a porcine model of chronic myocardial ischemia and in patients with refractory angina pectoris. However, the detailed molecular mechanisms for the SW-induced angiogenesis remain unclear. In this study, we thus examined the effects of SW irradiation on intracellular signaling pathways in vitro. Cultured human umbilical vein endothelial cells (HUVECs) were treated with 800 shots of low-energy SW (1 Hz at an energy level of 0.03 mJ/mm(2)). The SW therapy significantly upregulated mRNA expression and protein levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS). The SW therapy also enhanced phosphorylation of extracellular signal-regulated kinase 1/2 (Erk1/2) and Akt. Furthermore, the SW therapy enhanced phosphorylation of caveolin-1 and the expression of HUTS-4 that represents β1-integrin activity. These results suggest that caveolin-1 and β1-integrin are involved in the SW-induced activation of angiogenic signaling pathways. To further examine the signaling pathways involved in the SW-induced angiogenesis, HUVECs were transfected with siRNA of either β1-integrin or caveolin-1. Knockdown of either caveolin-1 or β1-integrin suppressed the SW-induced phosphorylation of Erk1/2 and Akt and upregulation of VEGF and eNOS. Knockdown of either caveolin-1 or β1-integrin also suppressed SW-induced enhancement of HUVEC migration in scratch assay. These results suggest that activation of mechanosensors on cell membranes, such as caveolin-1 and β1-integrin, and subsequent phosphorylation of Erk and Akt may play pivotal roles in the SW-induced angiogenesis. PMID:27413171

  14. Shock-induced heating and millisecond boiling in gels and tissue due to high intensity focused ultrasound.

    PubMed

    Canney, Michael S; Khokhlova, Vera A; Bessonova, Olga V; Bailey, Michael R; Crum, Lawrence A

    2010-02-01

    Nonlinear propagation causes high-intensity ultrasound waves to distort and generate higher harmonics, which are more readily absorbed and converted to heat than the fundamental frequency. Although such nonlinear effects have been investigated previously and found to not significantly alter high-intensity focused ultrasound (HIFU) treatments, two results reported here change this paradigm. One is that at clinically relevant intensity levels, HIFU waves not only become distorted but form shock waves in tissue. The other is that the generated shock waves heat the tissue to boiling in much less time than predicted for undistorted or weakly distorted waves. In this study, a 2-MHz HIFU source operating at peak intensities up to 25,000 W/cm(2) was used to heat transparent tissue-mimicking phantoms and ex vivo bovine liver samples. Initiation of boiling was detected using high-speed photography, a 20-MHz passive cavitation detector and fluctuation of the drive voltage at the HIFU source. The time to boil obtained experimentally was used to quantify heating rates and was compared with calculations using weak shock theory and the shock amplitudes obtained from nonlinear modeling and measurements with a fiber optic hydrophone. As observed experimentally and predicted by calculations, shocked focal waveforms produced boiling in as little as 3 ms and the time to initiate boiling was sensitive to small changes in HIFU output. Nonlinear heating as a result of shock waves is therefore important to HIFU, and clinicians should be aware of the potential for very rapid boiling because it alters treatments. PMID:20018433

  15. Shock-induced heating and millisecond boiling in gels and tissue due to high intensity focused ultrasound

    PubMed Central

    Canney, Michael S.; Khokhlova, Vera A.; Bessonova, Olga V.; Bailey, Michael R.; Crum, Lawrence A.

    2009-01-01

    Nonlinear propagation causes high intensity ultrasound waves to distort and generate higher harmonics, which are more readily absorbed and converted to heat than the fundamental frequency. Although such nonlinear effects have previously been investigated and found not to significantly alter high intensity focused ultrasound (HIFU) treatments, two results reported here change this paradigm. One is that at clinically relevant intensity levels, HIFU waves not only become distorted but form shock waves in tissue. The other is that the generated shock waves heat the tissue to boiling in much less time than predicted for undistorted or weakly distorted waves. In this study, a 2-MHz HIFU source operating at peak intensities up to 25,000 W/cm2 was used to heat transparent tissue-mimicking phantoms and ex vivo bovine liver samples. Initiation of boiling was detected using high-speed photography, a 20-MHz passive cavitation detector, and fluctuation of the drive voltage at the HIFU source. The time to boil obtained experimentally was used to quantify heating rates and was compared to calculations using weak shock theory and the shock amplitudes obtained from nonlinear modeling and from measurements with a fiber optic hydrophone. As observed experimentally and predicted by calculations, shocked focal waveforms produced boiling in as little as 3 ms and the time to initiate boiling was sensitive to small changes in HIFU output. Nonlinear heating due to shock waves is therefore important to HIFU and clinicians should be aware of the potential for very rapid boiling since it alters treatments. PMID:20018433

  16. A novel platform to study magnetized high-velocity collisionless shocks

    SciTech Connect

    Higginson, D. P.; Korneev, Ph; Béard, J.; Chen, S. N.; d'Humières, E.; Pépin, H.; Pikuz, S.; Pollock, B.; Riquier, R.; Tikhonchuk, V.; Fuchs, J.

    2014-12-13

    An experimental platform to study the interaction of two colliding high-velocity (0.01–0.2c; 0.05–20 MeV) proton plasmas in a high strength (20 T) magnetic field is introduced. This platform aims to study the collision of magnetized plasmas accelerated via the Target-Normal-Sheath-Acceleration mechanism and initially separated by distances of a few hundred microns. The plasmas are accelerated from solid targets positioned inside a few cubic millimeter cavity located within a Helmholtz coil that provides up to 20 T magnetic fields. Various parameters of the plasmas at their interaction location are estimated. These show an interaction that is highly non-collisional, and that becomes more and more dominated by the magnetic fields as time progresses (from 5 to 60 ps). Particle-in-cell simulations are used to reproduce the initial acceleration of the plasma both via simulations including the laser interaction and via simulations that start with preheated electrons (to save dramatically on computational expense). The benchmarking of such simulations with the experiment and with each other will be used to understand the physical interaction when a magnetic field is applied. In conclusion, the experimental density profile of the interacting plasmas is shown in the case without an applied magnetic magnetic field, so to show that without an applied field that the development of high-velocity shocks, as a result of particle-to-particle collisions, is not achievable in the configuration considered.

  17. Experimental High Energy Neutrino Astrophysics

    SciTech Connect

    Distefano, Carla

    2005-10-12

    Neutrinos are considered promising probes for high energy astrophysics. More than four decades after deep water Cerenkov technique was proposed to detect high energy neutrinos. Two detectors of this type are successfully taking data: BAIKAL and AMANDA. They have demonstrated the feasibility of the high energy neutrino detection and have set first constraints on TeV neutrino production astrophysical models. The quest for the construction of km3 size detectors have already started: in the South Pole, the IceCube neutrino telescope is under construction; the ANTARES, NEMO and NESTOR Collaborations are working towards the installation of a neutrino telescope in the Mediterranean Sea.

  18. High-energy spectroscopic astrophysics

    NASA Astrophysics Data System (ADS)

    Güdel, Manuel; Walter, Roland

    After three decades of intense research in X-ray and gamma-ray astronomy, the time was ripe to summarize basic knowledge on X-ray and gamma-ray spectroscopy for interested students and researchers ready to become involved in new high-energy missions. This volume exposes both the scientific basics and modern methods of high-energy spectroscopic astrophysics. The emphasis is on physical principles and observing methods rather than a discussion of particular classes of high-energy objects, but many examples and new results are included in the three chapters as well.

  19. Pre-plasma effect on energy transfer from laser beam to shock wave generated in solid target

    SciTech Connect

    Pisarczyk, T.; Kalinowska, Z.; Badziak, J.; Borodziuk, S.; Chodukowski, T.; Kasperczuk, A.; Parys, P.; Rosinski, M.; Gus'kov, S. Yu.; Demchenko, N. N.; Batani, D.; Antonelli, L.; Folpini, G.; Maheut, Y.; Baffigi, F.; Cristoforetti, G.; Gizzi, L. A.; Koester, P.; Labate, L.; Krousky, E.; and others

    2014-01-15

    Efficiency of the laser radiation energy transport into the shock wave generated in layered planar targets (consisting of massive Cu over coated by thin CH layer) was investigated. The targets were irradiated using two laser pulses. The 1ω pulse with the energy of ∼50 J produced a pre-plasma, imitating the corona of the pre-compressed inertial confinement fusion target. The second main pulse used the 1ω or 3ω laser harmonics with the energy of ∼200 J. The influence of the pre-plasma on parameters of the shock wave was determined from the crater volume measurements and from the electron density distribution measured by 3-frame interferometry. The experimental results show that the energy transport by fast electrons provides a definite contribution to the dynamics of the ablative process, to the shock wave generation, and to the ablation pressure in dependence on the target irradiation conditions. The strong influence of the pre-plasma on the investigated process was observed in the 1ω case. Theoretical analysis supports the explanation of experimental results.

  20. Suprathermal Electrons at Saturn's Bow Shock

    NASA Astrophysics Data System (ADS)

    Masters, A.; Sulaiman, A. H.; Sergis, N.; Stawarz, L.; Fujimoto, M.; Coates, A. J.; Dougherty, M. K.

    2016-07-01

    The leading explanation for the origin of galactic cosmic rays is particle acceleration at the shocks surrounding young supernova remnants (SNRs), although crucial aspects of the acceleration process are unclear. The similar collisionless plasma shocks frequently encountered by spacecraft in the solar wind are generally far weaker (lower Mach number) than these SNR shocks. However, the Cassini spacecraft has shown that the shock standing in the solar wind sunward of Saturn (Saturn's bow shock) can occasionally reach this high-Mach number astrophysical regime. In this regime Cassini has provided the first in situ evidence for electron acceleration under quasi-parallel upstream magnetic conditions. Here we present the full picture of suprathermal electrons at Saturn's bow shock revealed by Cassini. The downstream thermal electron distribution is resolved in all data taken by the low-energy electron detector (CAPS-ELS, <28 keV) during shock crossings, but the higher energy channels were at (or close to) background. The high-energy electron detector (MIMI-LEMMS, >18 keV) measured a suprathermal electron signature at 31 of 508 crossings, where typically only the lowest energy channels (<100 keV) were above background. We show that these results are consistent with the theory in which the “injection” of thermal electrons into an acceleration process involves interaction with whistler waves at the shock front, and becomes possible for all upstream magnetic field orientations at high Mach numbers like those of the strong shocks around young SNRs. A future dedicated study will analyze the rare crossings with evidence for relativistic electrons (up to ˜1 MeV).

  1. High energy physics

    SciTech Connect

    Kernan, A.; Shen, B.C.; Ma, E.

    1997-07-01

    Hadron collider studies will focus on: (i) the search for the top quark with the newly installed D0 detector at the Fermilab Tevatron collider, (ii) the upgrade of the D0 detector to match the new main injector luminosity and (iii) R&D on silicon microstrip tracking devices for the SSC. High statistics studies of Z{sup 0} decay will continue with the OPAL detector at LEP. These studies will include a direct measurement of Z decay to neutrinos, the search for Higgs and heavy quark decays of Z. Preparations for the Large Scintillation Neutrino Detector (LSND) to measure neutrino oscillations at LAMPF will focus on data acquisition and testing of photomultiplier tubes. In the theoretical area E. Ma will concentrate on mass-generating radiative mechanisms for light quarks and leptons in renormalizable gauge field theories. J. Wudka`s program includes a detailed investigation of the magnetic-flip approach to the solar neutrino.

  2. Novel mechanism of gene transfection by low-energy shock wave

    PubMed Central

    Hoon Ha, Chang; Cheol Lee, Seok; Kim, Sunghyen; Chung, Jihwa; Bae, Hasuk; Kwon, Kihwan

    2015-01-01

    Extracorporeal shock wave (SW) therapy has been studied in the transfection of naked nucleic acids into various cell lines through the process of sonoporation, a process that affects the permeation of cell membranes, which can be an effect of cavitation. In this study, siRNAs were efficiently transfected into primary cultured cells and mouse tumor tissue via SW treatment. Furthermore SW-induced siRNA transfection was not mediated by SW-induced sonoporation, but by microparticles (MPs) secreted from the cells. Interestingly, the transfection effect of the siRNAs was transferable through the secreted MPs from human umbilical vein endothelial cell (HUVEC) culture medium after treatment with SW, into HUVECs in another culture plate without SW treatment. In this study, we suggest for the first time a mechanism of gene transfection induced by low-energy SW through secreted MPs, and show that it is an efficient physical gene transfection method in vitro and represents a safe therapeutic strategy for site-specific gene delivery in vivo. PMID:26243452

  3. Relativistic Shocks: Particle Acceleration and Magnetization

    NASA Astrophysics Data System (ADS)

    Sironi, L.; Keshet, U.; Lemoine, M.

    2015-10-01

    We review the physics of relativistic shocks, which are often invoked as the sources of non-thermal particles in pulsar wind nebulae (PWNe), gamma-ray bursts (GRBs), and active galactic nuclei (AGN) jets, and as possible sources of ultra-high energy cosmic-rays. We focus on particle acceleration and magnetic field generation, and describe the recent progress in the field driven by theory advances and by the rapid development of particle-in-cell (PIC) simulations. In weakly magnetized or quasi parallel-shocks (i.e. where the magnetic field is nearly aligned with the flow), particle acceleration is efficient. The accelerated particles stream ahead of the shock, where they generate strong magnetic waves which in turn scatter the particles back and forth across the shock, mediating their acceleration. In contrast, in strongly magnetized quasi-perpendicular shocks, the efficiencies of both particle acceleration and magnetic field generation are suppressed. Particle acceleration, when efficient, modifies the turbulence around the shock on a long time scale, and the accelerated particles have a characteristic energy spectral index of s_{γ}˜eq2.2 in the ultra-relativistic limit. We discuss how this novel understanding of particle acceleration and magnetic field generation in relativistic shocks can be applied to high-energy astrophysical phenomena, with an emphasis on PWNe and GRB afterglows.

  4. Future of high energy physics

    SciTech Connect

    Panofsky, W.K.H.

    1984-06-01

    A rough overview is given of the expectations for the extension of high energy colliders and accelerators into the xtremely high energy range. It appears likely that the SSC or something like it will be the last gasp of the conventional method of producing high energy proton-proton collisions using synchrotron rings with superconducting magnets. It is likely that LEP will be the highest energy e+e/sup -/ colliding beam storage ring built. The future beyond that depends on the successful demonstrations of new technologies. The linear collider offers hope in this respect for some extension in energy for electrons, and maybe even for protons, but is too early to judge whether, by how much, or when such an extension will indeed take place.

  5. Colliding Two Shocks: 1-D full Particle-in-Cell Simulation

    NASA Astrophysics Data System (ADS)

    Nakanotani, Masaru; Hada, T.; Matsukiyo, Shuichi; Mazelle, Christian

    2016-07-01

    Shock-shock interactions occur on various places in space and the interaction can produce high energy particles. A coronal mass ejection driven shock can collide with the Earth's bow shock [Hietala et al., 2011]. This study reported that ions are accelerated by the first Fermi acceleration between the two shocks before the collision. An electron acceleration through an interplanetary shock-Earth's bow shock interaction was also reported [Terasawa et al., 1997]. Shock-shock interactions can occur in astrophysical phenomena as well as in the heliosphere. For example, a young supernova shock can collide with the wind termination shock of a massive star if they are close to each other [Bykov et al., 2013]. Although hybrid simulations (ions and electrons treated as super-particles and mass-less fluid, respectively) were carried out to understand the kinetic nature of a shock-shock interaction [Cargill et al., 1986], hybrid simulations cannot resolve electron dynamics and non-thermal electrons. We, therefore, use one-dimensional full particle-in-cell (PIC) simulations to investigate a shock-shock interaction in which two shocks collide head-on. In a case of quasi-perpendicular shocks, electrons are accelerated by the mirror reflection between the two shocks before the collision (Fermi acceleration). On the other hand, because ions cannot go back upstream, the electron acceleration mechanism does not occur for ions. In a case of quasi-parallel shocks, ions can go back upstream and are accelerated at the shocks. The accelerated ions have great effect on the shock structure.

  6. Resolving the shocked gas in HH 54 with Herschel. CO line mapping at high spatial and spectral resolution

    NASA Astrophysics Data System (ADS)

    Bjerkeli, P.; Liseau, R.; Brinch, C.; Olofsson, G.; Santangelo, G.; Cabrit, S.; Benedettini, M.; Black, J. H.; Herczeg, G.; Justtanont, , K.; Kristensen, L. E.; Larsson, B.; Nisini, B.; Tafalla, M.

    2014-11-01

    Context. The HH 54 shock is a Herbig-Haro object, located in the nearby Chamaeleon II cloud. Observed CO line profiles are due to a complex distribution in density, temperature, velocity, and geometry. Aims: Resolving the HH 54 shock wave in the far-infrared (FIR) cooling lines of CO constrain the kinematics, morphology, and physical conditions of the shocked region. Methods: We used the PACS and SPIRE instruments on board the Herschel space observatory to map the full FIR spectrum in a region covering the HH 54 shock wave. Complementary Herschel-HIFI, APEX, and Spitzer data are used in the analysis as well. The observed features in the line profiles are reproduced using a 3D radiative transfer model of a bow-shock, constructed with the Line Modeling Engine code (LIME). Results: The FIR emission is confined to the HH 54 region and a coherent displacement of the location of the emission maximum of CO with increasing J is observed. The peak positions of the high-J CO lines are shifted upstream from the lower J CO lines and coincide with the position of the spectral feature identified previously in CO (10-9) profiles with HIFI. This indicates a hotter molecular component in the upstream gas with distinct dynamics. The coherent displacement with increasing J for CO is consistent with a scenario where IRAS12500 - 7658 is the exciting source of the flow, and the 180 K bow-shock is accompanied by a hot (800 K) molecular component located upstream from the apex of the shock and blueshifted by -7 km s-1. The spatial proximity of this knot to the peaks of the atomic fine-structure emission lines observed with Spitzer and PACS ([O i]63, 145 μm) suggests that it may be associated with the dissociative shock as the jet impacts slower moving gas in the HH 54 bow-shock. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  7. Super-strengthening and stabilizing with carbon nanotube harnessed high density nanotwins in metals by shock loading.

    PubMed

    Lin, Dong; Saei, Mojib; Suslov, Sergey; Jin, Shengyu; Cheng, Gary J

    2015-01-01

    CNTs reinforced metal composites has great potential due to their superior properties, such as light weight, high strength, low thermal expansion and high thermal conductivity. The current strengthening mechanisms of CNT/metal composite mainly rely on CNTs' interaction with dislocations and CNT's intrinsic high strength. Here we demonstrated that laser shock loading the CNT/metal composite results in high density nanotwins, stacking fault, dislocation around the CNT/metal interface. The composites exhibit enhanced strength with excellent stability. The results are interpreted by both molecular dynamics simulation and experiments. It is found the shock wave interaction with CNTs induces a stress field, much higher than the applied shock pressure, surrounding the CNT/metal interface. As a result, nanotwins were nucleated under a shock pressure much lower than the critical values to generate twins in metals. This hybrid unique nanostructure not only enhances the strength, but also stabilize the strength, as the nanotwin boundaries around the CNTs help pin the dislocation movement. PMID:26493533

  8. Super-strengthening and stabilizing with carbon nanotube harnessed high density nanotwins in metals by shock loading

    NASA Astrophysics Data System (ADS)

    Lin, Dong; Saei, Mojib; Suslov, Sergey; Jin, Shengyu; Cheng, Gary J.

    2015-10-01

    CNTs reinforced metal composites has great potential due to their superior properties, such as light weight, high strength, low thermal expansion and high thermal conductivity. The current strengthening mechanisms of CNT/metal composite mainly rely on CNTs’ interaction with dislocations and CNT’s intrinsic high strength. Here we demonstrated that laser shock loading the CNT/metal composite results in high density nanotwins, stacking fault, dislocation around the CNT/metal interface. The composites exhibit enhanced strength with excellent stability. The results are interpreted by both molecular dynamics simulation and experiments. It is found the shock wave interaction with CNTs induces a stress field, much higher than the applied shock pressure, surrounding the CNT/metal interface. As a result, nanotwins were nucleated under a shock pressure much lower than the critical values to generate twins in metals. This hybrid unique nanostructure not only enhances the strength, but also stabilize the strength, as the nanotwin boundaries around the CNTs help pin the dislocation movement.

  9. Super-strengthening and stabilizing with carbon nanotube harnessed high density nanotwins in metals by shock loading

    PubMed Central

    Lin, Dong; Saei, Mojib; Suslov, Sergey; Jin, Shengyu; Cheng, Gary J.

    2015-01-01

    CNTs reinforced metal composites has great potential due to their superior properties, such as light weight, high strength, low thermal expansion and high thermal conductivity. The current strengthening mechanisms of CNT/metal composite mainly rely on CNTs’ interaction with dislocations and CNT’s intrinsic high strength. Here we demonstrated that laser shock loading the CNT/metal composite results in high density nanotwins, stacking fault, dislocation around the CNT/metal interface. The composites exhibit enhanced strength with excellent stability. The results are interpreted by both molecular dynamics simulation and experiments. It is found the shock wave interaction with CNTs induces a stress field, much higher than the applied shock pressure, surrounding the CNT/metal interface. As a result, nanotwins were nucleated under a shock pressure much lower than the critical values to generate twins in metals. This hybrid unique nanostructure not only enhances the strength, but also stabilize the strength, as the nanotwin boundaries around the CNTs help pin the dislocation movement. PMID:26493533

  10. High interindividual variability in dose-dependent reduction in speed of movement after exposing C. elegans to shock waves

    PubMed Central

    Angstman, Nicholas B.; Kiessling, Maren C.; Frank, Hans-Georg; Schmitz, Christoph

    2015-01-01

    In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI. PMID:25705183

  11. Optimization of magnetically accelerated, ultra-high velocity aluminum flyer plates for use in plate impact, shock wave experiments.

    SciTech Connect

    Cochrane, Kyle Robert; Knudson, Marcus D.; Slutz, Stephen A.; Lemke, Raymond William; Davis, J. P.; Harjes, Henry Charles III; Giunta, Anthony Andrew; Bliss, David Emery

    2005-05-01

    The intense magnetic field produced by the 20 MA Z accelerator is used as an impulsive pressure source to accelerate metal flyer plates to high velocity for the purpose of performing plate impact, shock wave experiments. This capability has been significantly enhanced by the recently developed pulse shaping capability of Z, which enables tailoring the rise time to peak current for a specific material and drive pressure to avoid shock formation within the flyer plate during acceleration. Consequently, full advantage can be taken of the available current to achieve the maximum possible magnetic drive pressure. In this way, peak magnetic drive pressures up to 490 GPa have been produced, which shocklessly accelerated 850 {micro}m aluminum (6061-T6) flyer plates to peak velocities of 34 km/s. We discuss magnetohydrodynamic (MHD) simulations that are used to optimize the magnetic pressure for a given flyer load and to determine the shape of the current rise time that precludes shock formation within the flyer during acceleration to peak velocity. In addition, we present results pertaining to plate impact, shock wave experiments in which the aluminum flyer plates were magnetically accelerated across a vacuum gap and impacted z-cut, {alpha}-quartz targets. Accurate measurements of resulting quartz shock velocities are presented and analyzed through high-fidelity MHD simulations enhanced using optimization techniques. Results show that a fraction of the flyer remains at solid density at impact, that the fraction of material at solid density decreases with increasing magnetic pressure, and that the observed abrupt decrease in the quartz shock velocity is well correlated with the melt transition in the aluminum flyer.

  12. High interindividual variability in dose-dependent reduction in speed of movement after exposing C. elegans to shock waves.

    PubMed

    Angstman, Nicholas B; Kiessling, Maren C; Frank, Hans-Georg; Schmitz, Christoph

    2015-01-01

    In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI. PMID:25705183

  13. Advance warning of high-speed ejecta based on real-time shock analyses: When fast-moving ejecta appear to be overtaking slow-moving shocks

    NASA Astrophysics Data System (ADS)

    Paulson, Kristoff W.; Taylor, David K.; Smith, Charles W.; Vasquez, Bernard J.; Hu, Q.

    2012-12-01

    Interplanetary shocks propagating into the magnetosphere can have significant space weather consequences. However, for many purposes it is the ejecta behind the shock that is the greater threat. The ejecta can be fast moving, impart significant momentum upon the magnetopause, and may contain a flux rope with strong southward magnetic fields. When transient solar wind activity strikes the magnetosphere, it can lead to enhanced magnetospheric currents and elevated radiation levels in the near-Earth environment. It is therefore desirable to use the observed shocks ahead of ejecta to predict any aspects of the approaching ejecta that can be predicted. We have examined 39 shocks observed by the Advanced Composition Explorer spacecraft in the years 1998 to 2003. Within the selection are shocks that were chosen because they appear to propagate significantly more slowly than the speed of the ejecta behind it. While appearing at first to be a contradiction, we show that the shocks are propagating across the radial direction and at significant angles to the velocity of the ejecta. These slow-moving shocks are actually precursors of fast-moving and potentially significant ejecta. Reversing the analysis, we are able to predict the peak speed of the ejecta well in advance of their observation, up to or in excess of 10 h following the shock crossing, when slow-moving shocks are seen, and we have incorporated this feature into our real-time shock analysis.

  14. High energy physics

    SciTech Connect

    Not Available

    1992-04-10

    The Counter Group continues to work on data analysis for Fermilab Experiment E653. Altogether, they expect several thousand reconstructed charm events and approximately 25 B pair events of which 12 have been observed thus far. Preparation continue for Fermilab Experiment E781, a high statistics study of charm baryon production. In the Theory Group, Cutkosky and collaborators study hadron phenomenology and non-perturbative QCD calculations. Levine has a long standing program in computational QED to obtain improved theoretical values for g-2 of the electron. Wolfenstein, Li, and their collaborators have worked on areas of weak interaction phenomenology that may yield insights beyond the standard model, e.g. CP violation and non-zero neutrino masses. Holman has been concerned with phase transitions in gauge theories relevant to cosmological problems. During 1991 most of the group effort was concentrated on the L3 experiment at CERN. Highlights of the results from the analysis of the Z[degrees] resonance include (a) a measurement of the strong coupling constant [alpha][sub s] for b quarks (b) a precision measurement of the average time of B hadrons and (c) a direct determination of the number of light neutrino faculties from the reaction e[sup +]e[sup [minus

  15. Shock Acceleration of Electrons: The Role of Mach Number and Shock Surface Fluctuations

    NASA Astrophysics Data System (ADS)

    Burgess, David; Haynes, Christopher; Gingell, Peter; Hellinger, Petr

    2015-04-01

    Energetic electrons are a common feature of interplanetary shocks and planetary bow shocks, and they are invoked as a key component of models of nonthermal radio emission, such as solar radio bursts and radio emission in the outer heliosphere. A simulation study is carried out of electron acceleration for quasi-perpendicular shocks, typical of the shocks in the solar wind. Two and three-dimensional self-consistent hybrid simulations of quasi-perpendicular shocks provide the electric and magnetic fields in which test particle electrons are followed. A range of different Mach numbers and shock normal angles are investigated. When the Mach number is low, the results agree with theory assuming magnetic moment conserving reflection, with electron energy gains of a factor only 2 to 3. For high Mach numbers, i.e., super-critical, the shock front has a dynamic rippled character. In this case the electrons can suffer scattering in the ion-scale turbulence within the shock layer, producing higher energy gains and some modification of the loss-cone distribution functions predicted by magnetic moment conservation. In addition, acceleration to high energies is present over a wider range of shock normal angles. Distribution functions for reflected and transmitted electrons are computed based on initial upstream kappa distributions similar to the solar wind electron distribution, allowing quantitative comparisons with observations. In addition, the impact of upstream turbulence on the structure of low Mach number shocks is examined, in order to investigate whether such shocks can also produce efficient acceleration due to additional electron scattering.

  16. Shock-drift accelerated electrons and n-distribution

    NASA Astrophysics Data System (ADS)

    Vandas, Marek; Karlicky, Marian

    2016-07-01

    Recently soft X-ray spectra observed during the impulsive phase of several solar flares have been explained by the presence of the n-distribution function of superthermal electrons. We examine if electrons with such a distribution function can be produced in a shock, e.g. in a flare termination shock. The distribution functions of reflected electrons at quasi-perpendicular shocks are analytically derived and compared with the n-distributions. We consider an influence of the electrostatic cross-shock potential, shock curvature, and a role of the upstream seed population on these distributions. We found that a high-energy part of the distribution of electrons reflected at a quasi-perpendicular shock could be very well fitted by the n-distribution. It gives a chance to detect the flare termination shock.

  17. Prediction of the shock arrival time with SEP observations

    NASA Astrophysics Data System (ADS)

    Qin, G.; Zhang, M.; Rassoul, H. K.

    2009-09-01

    Real-time prediction of the arrival times at Earth of shocks is very important for space weather research. Recently, various models for shock propagation are used to forecast the shock arriving times (SATs) with information of initial coronal shock and flare from near real-time radio and X-ray data. In this paper, we add the use of solar energetic particles (SEP) observation to improve the shock arrival time (SAT) prediction. High-energy SEPs originating from flares move to the Earth much faster than the shocks related to the same flares. We develop an SAT prediction model by combining a well-known shock propagation model, STOA, and the analysis of SEPs detected at Earth. We demonstrate that the SAT predictions are improved by the new model with the help of 38-53 keV electron SEP observations. In particular, the correct prediction to false alarm ratio is improved significantly.

  18. High energy physics

    SciTech Connect

    Not Available

    1992-04-10

    The Counter Group continues to work on data analysis for Fermilab Experiment E653. Altogether, they expect several thousand reconstructed charm events and approximately 25 B pair events of which 12 have been observed thus far. Preparation continue for Fermilab Experiment E781, a high statistics study of charm baryon production. In the Theory Group, Cutkosky and collaborators study hadron phenomenology and non-perturbative QCD calculations. Levine has a long standing program in computational QED to obtain improved theoretical values for g-2 of the electron. Wolfenstein, Li, and their collaborators have worked on areas of weak interaction phenomenology that may yield insights beyond the standard model, e.g. CP violation and non-zero neutrino masses. Holman has been concerned with phase transitions in gauge theories relevant to cosmological problems. During 1991 most of the group effort was concentrated on the L3 experiment at CERN. Highlights of the results from the analysis of the Z{degrees} resonance include (a) a measurement of the strong coupling constant {alpha}{sub s} for b quarks (b) a precision measurement of the average time of B hadrons and (c) a direct determination of the number of light neutrino faculties from the reaction e{sup +}e{sup {minus}} {yields} {nu}{bar {nu}}{gamma}. We also began a major upgrade of the L3 luminosity monitor by replacing PWC chamber by a Si strip system in front of the BGO calorimeters. Finally we have continued our SSC R&D work on BaF{sub 2} by joining the GEM collaboration.

  19. Energy spectra of high energy atmospheric neutrinos

    NASA Technical Reports Server (NTRS)

    Mitsui, K.; Minorikawa, Y.

    1985-01-01

    Focusing on high energy neutrinos ( or = 1 TeV), a new calculation of atmospheric neutrino intensities was carried out taking into account EMC effects observed in P-A collisions by accelerator, recent measurement of primary cosmic ray spectrum and results of cosmic ray muon spectrum and charge ratio. Other features of the present calculation are (1) taking into account kinematics of three body decays of kaons and charm particles in diffusion equations and (2) taking into account energy dependence of kaon production.

  20. Evidence of downstream high speed jets by a non-stationary and rippled front of quasi-parallel shock: 2-D hybrid simulations

    NASA Astrophysics Data System (ADS)

    Hao, Yufei; Lu, Quanming; Lembege, Bertrand; Huang, Can; Wu, Mingyu; Guo, Fan; Shan, Lican; Zheng, Jian; Wang, Shui

    2015-04-01

    Experimental observations from space missions (including Cluster more recently) have clearly revealed the existence of high speed jets (HSJ) in the downstream region of the quasi-parallel terrestrial bow shock. Presently, two-dimensional (2-D) hybrid simulations are performed to reproduce and investigate the formation of such HSJ through a rippled quasi-parallel shock front. The simulation results show (i) that such shock fronts are strongly nonstationary (self reformation) along the shock normal, and (ii) that ripples are evidenced along the shock front as the upstream ULF waves (excited by interaction between incoming and reflected ions) are convected back to the front by the solar wind and contribute to the rippling formation. Then, these ripples are inherent structures of a quasi-parallel shock and the self reformation of the shock is not synchronous along the surface of the shock front. As a consequence, new incoming solar wind ions interact differently at different locations along the shock surface, and some can be only deflected (instead of being decelerated) at locations where ripples are large enough to play the role of local « secondary » shock. Therefore, the ion bulk velocity is also different locally after ions are transmitted dowstream, and local high-speed jets patterns are formed somewhere downstream. After a short reminder of main quasi-parallel shock features, this presentation will focus (i) on experimental observations of HSJ, (ii) on our preliminary simulation results obtained on HSJ, (iii) on their relationship with local bursty patterns of (turbulent) magnetic field evidenced at the front, and (iv) on the spatial and time scales of HSJ to be compared later on with experimental observations. Such downstream HSJ are shown to be generated by the nonstationary shock front itself and do not require any upstream perturbations (such as tangential/rotational discontinuity, HFA, etc..) to be convected by the solar wind and to interact with the shock

  1. Supermagnetosonic Jets behind a Collisionless Quasiparallel Shock

    SciTech Connect

    Hietala, H.; Vainio, R.; Laitinen, T. V.; Vaivads, A.; Andreeova, K.; Palmroth, M.; Pulkkinen, T. I.; Koskinen, H. E. J.; Lucek, E. A.; Reme, H.

    2009-12-11

    The downstream region of a collisionless quasiparallel shock is structured containing bulk flows with high kinetic energy density from a previously unidentified source. We present Cluster multispacecraft measurements of this type of supermagnetosonic jet as well as of a weak secondary shock front within the sheath, that allow us to propose the following generation mechanism for the jets: The local curvature variations inherent to quasiparallel shocks can create fast, deflected jets accompanied by density variations in the downstream region. If the speed of the jet is super(magneto)sonic in the reference frame of the obstacle, a second shock front forms in the sheath closer to the obstacle. Our results can be applied to collisionless quasiparallel shocks in many plasma environments.

  2. 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.

  3. Comparison between holographic interferometry and high-speed videography techniques in the study of the reflection of plane shock waves

    NASA Astrophysics Data System (ADS)

    Barbosa, Filipe J.; Skews, Beric W.

    1997-05-01

    Double exposure holographic interferometry and high speed laser shadowgraph photography and videography are used to investigate the mutual reflection of two plane shock waves. Normally research on the transition from regular to Mach reflection is undertaken by allowing a plane shock wave to impinge on a wedge. However due to the boundary layer growth on the wedge, regular reflection persists at wedge angles higher than that allowed for by inviscid shock wave theory. Several bifurcated shock tubes have been constructed, wherein an initially planar shock wave is split symmetrically into two and then recombined at the trailing edge of a wedge. The plane of symmetry acts as an ideal rigid wall eliminating thermal and viscous boundary layer effects. The flow visualization system used needs to provide high resolution information on the shockwave, slipstream, triple point and vortex positions and angles. Initially shadowgraph and schlieren methods, with a Xenon light source, were used. These results, while proving useful, are not of a sufficient resolution to measure the Mach stem and slipstream lengths accurately enough in order to determine the transition point between regular and Mach reflection. To obtain the required image resolution a 2 joule double pulse ruby laser, with a 30 ns pulse duration, was used to make holographic interferograms. The combined advantages of holographic interferometry and the 30 ns pulse laser allows one to obtain much sharper definition, and more qualitative as well as quantitative information on the flow field. The disadvantages of this system are: the long time taken to develop holograms, the difficulty of aligning the pulse laser and the fact that only one image per test is obtained. Direct contact shadowgraphs were also obtained using the pulse ruby laser to help determine triple point trajectory angles. In order to provide further information a one million frames per second CCD camera, which can take up to 10 superimposed images, was

  4. Mach 4 and Mach 8 axisymmetric nozzles for a high-enthalpy shock tunnel

    NASA Technical Reports Server (NTRS)

    Jacobs, P. A.; Stalker, R. J.

    1991-01-01

    The performance of two axisymmetric nozzles which were designed to produce uniform, parallel flow with nominal Mach numbers of 4 and 8 is examined. A free-piston-driven shock tube was used to supply the nozzle with high-temperature, high-pressure test gas. The inviscid design procedure treated the nozzle expansion in two stages. Close to the nozzle throat, the nozzle wall was specified as conical and the gas flow was treated as a quasi-one-dimensional chemically-reacting flow. At the end of the conical expansion, the gas was assumed to be calorically perfect, and a contoured wall was designed (using method of characteristics) to convert the source flow into a uniform and parallel flow at the end of the nozzle. Performance was assessed by measuring Pitot pressures across the exit plane of the nozzles and, over the range of operating conditions examined, the nozzles produced satisfactory test flows. However, there were flow disturbances in the Mach 8 nozzle flow that persisted for significant times after flow initiation.

  5. Sound velocities in highly oriented pyrolytic graphite shocked to 18 GPa: Orientational order dependence and elastic instability

    NASA Astrophysics Data System (ADS)

    Lucas, Marcel; Winey, J. M.; Gupta, Y. M.

    2015-12-01

    Previous reports of rapid phase transformation above 18 GPa [Erskine and Nellis, Nature 349, 317 (1991)] and large elastic waves below 18 GPa [Lucas et al., J. Appl. Phys. 114, 093515 (2013)] for shock-compressed ZYB-grade highly oriented pyrolytic graphite (HOPG), but not for less oriented ZYH-grade HOPG, indicated a link between the orientational order dependence of the HOPG response above and below the phase transformation stress. To gain insight into this link and into the mechanical response of HOPG shocked to peak stresses approaching the phase transformation onset, the compressibility of ZYB- and ZYH-grade HOPG in the shocked state was examined using front surface impact experiments. Particle velocity histories and sound velocities were measured for peak stresses reaching 18 GPa. Although the locus of the measured peak stress-particle velocity states is indistinguishable for the two grades of HOPG, the measured sound velocities in the peak state reveal significant differences between the two grades. Specifically (1) the measured sound velocities are somewhat higher for ZYH-grade HOPG compared with ZYB-grade HOPG; (2) the measured sound velocities for ZYH-grade HOPG increase smoothly with compression, whereas those for ZYB-grade HOPG exhibit a significant reduction in the compression dependence from 12 GPa to 17 GPa and an abrupt increase from 17 GPa to 18 GPa; and (3) the longitudinal moduli, determined from the measured sound velocities, are smaller than the calculated bulk moduli for ZYB-grade HOPG shocked to peak stresses above 15 GPa, indicating the onset of an elastic instability. The present findings demonstrate that the softening of the longitudinal modulus (or elastic instability) presented here is linked to the large elastic waves and the rapid phase transformation reported previously—all observed only for shocked ZYB-grade HOPG. The elastic instability in shocked ZYB-grade HOPG is likely a precursor to the rapid phase transformation observed

  6. Shock-induced CO2 loss from CaCO3 - Implications for early planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1986-01-01

    Recovered samples from shock recovery experiments on single crystal calcite were subjected to thermogravimetric analysis to determine the amount of post-shock CO2, the decarbonization interval and the activation energy, for the removal of remaining CO2 in shock-loaded calcite. Comparison of post-shock CO2 with that initially present determines shock-induced CO2 loss as a function of shock pressure. Incipient to complete CO2 loss occurs over a pressure range of approximately 10 to approximately 70 GPa. Optical and scanning electron microscopy reveal structural changes which are related to the shock-loading. The occurrence of dark, diffuse areas, which can be resolved as highly vesticular areas as observed with a scanning electron microscope are interpreted as representing quenched partial melts, into which shock-released CO2 was injected. The experimental results are used to constrain models of shock-produced, primary CO2 atmospheres on the accreting terrestrial planets.

  7. Shock-induced CO2 loss from CaCO3: Implications for early planetary atmospheres

    NASA Technical Reports Server (NTRS)

    Lange, M. A.; Ahrens, T. J.

    1984-01-01

    Recovered samples from shock recovery experiments on single crystal calcite were subjected to thermogravimetric analysis to determine the amount of post-shock CO2, the decarbonization interval and the activation energy, for the removal of remaining CO2 in shock-loaded calcite. Comparison of post-shock CO2 with that initially present determines shock-induced CO2 loss as a function of shock pressure. Incipient to complete CO2 loss occurs over a pressure range of approximately 10 to approximately 70 GPa. Optical and scanning electron microscopy reveal structural changes, which are related to the shock-loading. The occurrence of dark, diffuse areas, which can be resolved as highly vesicular areas as observed with a scanning electron microscope are interpreted as representing quenched partial melts, into which shock-released CO2 was injected. The experimental results are used to constrain models of shock-produced, primary CO2 atmospheres on the accreting terrestrial planets.

  8. Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL

    NASA Astrophysics Data System (ADS)

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-06-01

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

  9. Planetary fluids He and NH/sub 3/ at high shock pressures and temperatures

    SciTech Connect

    Nellis, W.J.; Radousky, H.B.; Mitchell, A.C.; Holmes, N.C.; Ross, M.; Young, D.A.

    1985-04-01

    Liquid He at 4.3 K and 1 atm was shocked to 16 GPa (160 kbar) and 12,000 K and double-shocked to 56 GPa and 21,000 K. Liquid perturbation theory was 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 in the envelopes of the outer planets. A new fast optical pyrometer and a cryogenic specimen holder for liquid NH/sub 3/ were developed to measure shock temperatures of 4400 and 3600 K at pressures of 59 and 48 GPa. These conditions correspond to those in the ice layers in Uranus and Neptune. The shock temperature data are in reasonable agreement with an equation of state by Ree based on an intermolecular potential derived from NH/sub 3/ Hugoniot data.

  10. Gravitational shock waves of ultra-high energetic particles on curved spacetimes

    NASA Astrophysics Data System (ADS)

    Loustó, C. O.; Sánchez, N.

    1989-03-01

    We generalize the Dray and 't Hooft procedure to generate gravitational shock waves superimposed on curved background solutions of the vacuum Einstein equations in order to include sources and a non-zero cosmological constant for the backgrounds, and a charge for the shock waves (all that in D dimensions). We apply this generalization to the study of the gravitational shock wave of ultrarelativistic particles with kinetic and electromagnetic momenta p and pe in static spherically symmetric spacetimes and its effect on shifting the event horizon (the terms with p and pe give rise to different shifts). Examples of these shock waves on the Reissner-Nordstrom and the Schwarzschild-de Sitter (and Schwarzschild-anti de Sitter) spacetimes are considered. UA 336. Laboratoire associé au CNRS, Observatoire de Meudon et Ecole Normale Supérieure.

  11. Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL

    PubMed Central

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-01-01

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions. PMID:26086176

  12. Imaging shock waves in diamond with both high temporal and spatial resolution at an XFEL

    SciTech Connect

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-06-18

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

  13. Calcium ion on membrane fouling reduction and bioflocculation promotion in membrane bioreactor at high salt shock.

    PubMed

    Zhang, Haifeng; Fan, Xue; Wang, Bin; Song, Lianfa

    2016-01-01

    Fouling propensity of activated sludge in membrane bioreactor (MBR) is closely related to the disturbance of a salt shock. In this work, the characteristics of membrane fouling and bioflocculation were compared in two laboratory-scale MBRs (one with calcium addition, MBR-Ca, the other without, MBR-C) with a transient salt shock. Particle size distributions, zeta potential, relative hydrophobicity, modified fouling index, the content of polysaccharides, proteins and calcium ions in different layers of sludge were monitored prior to, during and after the salt shock. Comparison with MBR-C showed that the recovery time and fouling rate of MBR-Ca were reduced by 50% and 34%, respectively. Remarkable variations of sludge properties in terms of bioflocculation, such as larger particle sizes, higher relative hydrophobicity and zeta potential, lower polysaccharides in supernatant, higher proteins/polysaccharides ratio in slime and loose bound extracellular polymeric substances, were observed in MBR-Ca after the salt shock. PMID:26524252

  14. Investigation into low-temperatures influence on high explosive compounds sensitivity to shock-wave impacts

    SciTech Connect

    Averin, A.N.; Alekseev, A.V.; Batalov, S.V.; Loboiko, B.G.; Litvinov, B.V.; Sumin, V.D.; Filin, V.P.; Yagnakov, A.N.

    1996-05-01

    Study of shock-wave sensitivity of explosives under various temperatures is of great significance for correct analysis of safe application of different industrial processes, technologies, as well as for correct understanding of explosion initiation mechanism in (explosives). Currently, the influence of low, ({minus}100{degree}C{hor_ellipsis}{minus}200{degree}C) temperatures on explosive sensitivity to weak shock waves is poorly studied. This paper gives experimental results on the influence of low temperatures on the sensitivity of HMX{emdash}based explosives to weak shock-waves. In the present paper an attempt is made to experimentally determine dependence of HMX{emdash}based explosive sensitivity to weak shock waves on temperatures. The original technique of the experiment is presented in the report. {copyright} {ital 1996 American Institute of Physics.}

  15. AN EXPERIMENTAL STUDY OF SHOCK WAVES RESULTING FROM THE IMPACT OF HIGH VELOCITY MISSILES ON ANIMAL TISSUES

    PubMed Central

    Harvey, E. Newton; McMillen, J. Howard

    1947-01-01

    The spark shadowgram method of studying shock waves is described. It has been used to investigate the properties of such waves produced by the impact of a high velocity missile on the surface of water. The method can be adapted for study of behavior of shock waves in tissue by placing the tissue on a water surface or immersing it in water. Spark shadowgrams then reveal waves passing from tissue to water or reflected from tissue surfaces. Reflection and transmission of shock waves from muscle, liver, stomach, and intestinal wall are compared with reflection from non-living surfaces such as gelatin gel, steel, plexiglas, cork, and air. Because of its heterogeneous structure, waves transmitted by tissue are dispersed and appear as a series of wavelets. When the accoustical impedance (density x wave velocity) of a medium is less than that in which the wave is moving, reflection will occur with inversion of the wave; i.e., a high pressure wave will become a low pressure wave. This inversion occurs at an air surface and is illustrated by shadowgrams of reflection from stomach wall, from a segment of colon filled with gas, and from air-filled rubber balloons. Bone (human skull and beef ribs) shows good reflection and some transmission of shock waves. When steel is directly hit by a missile, clearly visible elastic waves pass from metal to water, but a similar direct hit on bone does not result in elastic waves strong enough to be detected by a spark shadowgram. PMID:19871617

  16. Electrostatic Assembly Preparation of High-Toughness Zirconium Diboride-Based Ceramic Composites with Enhanced Thermal Shock Resistance Performance.

    PubMed

    Zhang, Baoxi; Zhang, Xinghong; Hong, Changqing; Qiu, Yunfeng; Zhang, Jia; Han, Jiecai; Hu, PingAn

    2016-05-11

    The central problem of using ceramic as a structural material is its brittleness, which associated with rigid covalent or ionic bonds. Whiskers or fibers of strong ceramics such as silicon carbide (SiC) or silicon nitride (Si3N4) are widely embedded in a ceramic matrix to improve the strength and toughness. The incorporation of these insulating fillers can impede the thermal flow in ceramic matrix, thus decrease its thermal shock resistance that is required in some practical applications. Here we demonstrate that the toughness and thermal shock resistance of zirconium diboride (ZrB2)/SiC composites can be improved simultaneously by introducing graphene into composites via electrostatic assembly and subsequent sintering treatment. The incorporated graphene creates weak interfaces of grain boundaries (GBs) and optimal thermal conductance paths inside composites. In comparison to pristine ZrB2-SiC composites, the toughness of (2.0%) ZrB2-SiC/graphene composites exhibited a 61% increasing (from 4.3 to 6.93 MPa·m(1/2)) after spark plasma sintering (SPS); the retained strength after thermal shock increased as high as 74.8% at 400 °C and 304.4% at 500 °C. Present work presents an important guideline for producing high-toughness ceramic-based composites with enhanced thermal shock properties. PMID:27031536

  17. Model-Based Development of a Small-Scale Experiment for Non-Shock Ignition of High Explosives

    NASA Astrophysics Data System (ADS)

    White, Bradley; Springer, H.; Reaugh, J.

    2013-06-01

    We demonstrate a model-based approach for developing small-scale experiments for non-shock ignition of high explosives (HEs) that are representative of abnormal environmental conditions. While small-scale experiments are often favored over large-scale testing since costs are lower and samples sizes are amenable to early stage HE formulation, concerns remain about the ability to predict full-scale non-shock ignition response. Our approach is to perform simulations of full-scale systems (i.e., Skid test) to identify the localized material extrema states (e.g., pressure, pressure duration, shear stress, strain-rate) underlying the non-shock ignition mechanism. The extrema states then provide a metric for iterative model-based development of small-scale experiments using a drop-hammer system. We performed these simulations using the HERMES (High Explosive Response to MEchanical Stimuli) model in the multiphysics code, ALE3D. Optimized experimental geometries reach 10s MPa pressures over 1-3 ms durations while inducing a large degree of shear. The results of the experimental development and the effects of design variations on non-shock initiation response of Comp B will be presented. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344. This work was funded in part by the Joint DoD-DOE Munitions Program.

  18. 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

  19. Converging shocks in elastic-plastic solids

    NASA Astrophysics Data System (ADS)

    López Ortega, A.; 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=es(I1)+eh(ρ,ς), where es accounts for shear through the first invariant of the Cauchy-Green tensor, and eh 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., eh=eh(ρ), with a power-law dependence eh∝ρα, shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M∝[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∝R-(s-1) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part eh is that of an ideal gas, is also tested, recovering the strong-shock limit M∝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 hydrostatic part of the energy essentially commands the strong-shock behavior, the shear

  20. A particle image velocimeter for measuring the output of high energy detonators

    SciTech Connect

    Murphy, Michael J; Adrian, Ronald J; Clarke, Steven A

    2010-01-01

    Results from feasibility experiments are presented to confirm that tracer-particle motion resulting from mass-velocity fields created by driving high-energy detonator output into dynamic witness plates can be successfully measured using particle image velocimetry (PIV). Experimental results, application challenges, and PIV system development are presented. In shock mechanics research, the ability to quantitatively measure the state of compression of shocked materials in two and three dimensions based on particle tracer methods is of extreme importance since such measurements provide precise temporal snapshots of two and three-dimensional shock-induced velocity fields. This is especially true in the science of detonation physics where such measurements provide enormous insight into fundamental. questions for understanding shock-loading processes, effects of shock-front curvature, and mechanisms of energy conversion from stimulus to shock output. As an example, answering such questions is paramount to the understanding and development of newer, safer detonators. To date, few attempts have been made to develop and implement standard particle tracer techniques to measure shock-induced flows resulting from explosive devices. The experimental challenge lies in developing a methodology wherein a tracer particle's inertia does not hinder its ability to accurately move with the rapidly changing flow field. We have recently developed the ability to characterize the output of unloaded explosive initiators (e.g. exploding bridge wires, exploding foils, laser-driven plasmas, etc.) using an optically-based diagnostic consisting of an ultra-high speed, time-resolved PIV system and inert, transparent polymers serving as dynamic witness plates. Initiator output is directed into a witness plate, and measurements of shock and mass velocities are made in a two-dimensional plane aligned with the initiator centerline. The results allow initiator output to be quantified in any in

  1. High energy high brightness thin disk laser

    NASA Astrophysics Data System (ADS)

    Nixon, Matthew D.; Cates, Michael C.

    2012-11-01

    Boeing has been developing solid state lasers for high energy applications since 2004 using Yb:YAG thin disk lasers as pioneered by A. Giesen1 and commercialized by Trumpf Laser GmbH.2 In this paper, we report results of our second generation design and status of a third generation we are currently developing, which will produce 35 kW and a beam quality <2.

  2. A novel platform to study magnetized high-velocity collisionless shocks

    DOE PAGESBeta

    Higginson, D. P.; Korneev, Ph; Béard, J.; Chen, S. N.; d'Humières, E.; Pépin, H.; Pikuz, S.; Pollock, B.; Riquier, R.; Tikhonchuk, V.; et al

    2014-12-13

    An experimental platform to study the interaction of two colliding high-velocity (0.01–0.2c; 0.05–20 MeV) proton plasmas in a high strength (20 T) magnetic field is introduced. This platform aims to study the collision of magnetized plasmas accelerated via the Target-Normal-Sheath-Acceleration mechanism and initially separated by distances of a few hundred microns. The plasmas are accelerated from solid targets positioned inside a few cubic millimeter cavity located within a Helmholtz coil that provides up to 20 T magnetic fields. Various parameters of the plasmas at their interaction location are estimated. These show an interaction that is highly non-collisional, and that becomesmore » more and more dominated by the magnetic fields as time progresses (from 5 to 60 ps). Particle-in-cell simulations are used to reproduce the initial acceleration of the plasma both via simulations including the laser interaction and via simulations that start with preheated electrons (to save dramatically on computational expense). The benchmarking of such simulations with the experiment and with each other will be used to understand the physical interaction when a magnetic field is applied. In conclusion, the experimental density profile of the interacting plasmas is shown in the case without an applied magnetic magnetic field, so to show that without an applied field that the development of high-velocity shocks, as a result of particle-to-particle collisions, is not achievable in the configuration considered.« less

  3. An experimental study on aerodynamic characteristics of standard model HB-2 in high enthalpy shock tunnel HIEST

    NASA Astrophysics Data System (ADS)

    Sato, K.; Komuro, T.; Tanno, H.; Ueda, S.; Itoh, K.; Kuchiishi, S.; Watanabe, S.

    Force measurement of a standard model HB-2 was performed in high enthalpy shock tunnel HIEST to study its aerodynamic characteristics. The force measurement results were compared with that obtained in conventional 1.27m hypersonic wind tunnel HWT1. The comparison showed that HIEST results agreed well with that of HWT1 in case of low enthalpy condition. The real gas effect on aerodynamic characteristics was also studied in case of high enthalpy condition.

  4. Fatigue life enhancement of high reliability metallic components by laser shock processing

    NASA Astrophysics Data System (ADS)

    Ocaña, J. L.; Porro, J. A.; Díaz, M.; Ruiz de Lara, L.; Correa, C.; Peral, D.

    2015-03-01

    Laser shock processing (LSP) is increasingly applied as an effective technology for the improvement of metallic materials mechanical properties in different types of components as a means of enhancement of their mechanical behavior. As reported in the literature, a main effect resulting from the application of the LSP technique consists on the generation of relatively deep compression residual stresses field into metallic alloy pieces allowing the life improvement of the treated specimens against wear, crack growth and stress corrosion cracking. Additional results accomplished by the authors in the line of practical development of the LSP technique at an experimental level (aiming its integral assessment from an interrelated theoretical and experimental point of view) are presented in this paper. Concretely, experimental results on the residual stress profiles and associated mechanical properties modification successfully reached in typical materials under different LSP irradiation conditions are presented along with a practical correlated analysis on the protective character of the residual stress profiles obtained under different irradiation strategies. In this case, the specific behavior of a widely used material in high reliability components (especially in nuclear and biomedical applications) as AISI 316L is analyzed, the effect of possible "in-service" thermal conditions on the relaxation of the LSP effects being specifically characterized.

  5. Laser energy deposition effectiveness on shock-wave boundary-layer interactions over cylinder-flare combinations

    NASA Astrophysics Data System (ADS)

    Osuka, T.; Erdem, E.; Hasegawa, N.; Majima, R.; Tamba, T.; Yokota, S.; Sasoh, A.; Kontis, K.

    2014-09-01

    The effects of repetitive laser-pulse energy depositions (5.5 mJ/pulse) onto a shock wave-boundary layer interaction region over cylinder-flare model in a Mach 1.92 flow are experimentally investigated. Depending on the nose shape and the flare angle, the flow patterns are subdivided to two; separated flow in which a slip line and a strong separation shock wave originated in the nose-cylinder junction appears, and a non-separated flow in which a slip line is not observed and the re-attachment shock wave is much weaker. At flare angles around 30°, the separation can be suppressed by laser energy deposition even of down to 5 kHz. The Schlieren-visualized flow patterns are well correlated to the drag characteristics, in which a larger drag is obtained without separation. A possible scenario of the separation control is that the disturbance introduced by the baroclinic vortex ring induced the boundary layer transition so that it became robust against the adverse pressure gradient. Under marginal conditions, dual mode flow patterns, that is, a partial and full suppression modes are obtained under the same operation conditions.

  6. Intense laser driven collision-less shock and ion acceleration in magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Mima, K.; Jia, Q.; Cai, H. B.; Taguchi, T.; Nagatomo, H.; Sanz, J. R.; Honrubia, J.

    2016-05-01

    The generation of strong magnetic field with a laser driven coil has been demonstrated by many experiments. It is applicable to the magnetized fast ignition (MFI), the collision-less shock in the astrophysics and the ion shock acceleration. In this paper, the longitudinal magnetic field effect on the shock wave driven by the radiation pressure of an intense short pulse laser is investigated by theory and simulations. The transition of a laminar shock (electro static shock) to the turbulent shock (electromagnetic shock) occurs, when the external magnetic field is applied in near relativistic cut-off density plasmas. This transition leads to the enhancement of conversion of the laser energy into high energy ions. The enhancement of the conversion efficiency is important for the ion driven fast ignition and the laser driven neutron source. It is found that the total number of ions reflected by the shock increases by six time when the magnetic field is applied.

  7. Characterization of Saturn's bow shock: Magnetic field observations of quasi-perpendicular shocks

    NASA Astrophysics Data System (ADS)

    Sulaiman, A. H.; Masters, A.; Dougherty, M. K.

    2016-05-01

    Collisionless shocks vary drastically from terrestrial to astrophysical regimes resulting in radically different characteristics. This poses two complexities. First, separating the influences of these parameters on physical mechanisms such as energy dissipation. Second, correlating observations of shock waves over a wide range of each parameter, enough to span across different regimes. Investigating the latter has been restricted since the majority of studies on shocks at exotic regimes (such as supernova remnants) have been achieved either remotely or via simulations, but rarely by means of in situ observations. Here we present the parameter space of MA bow shock crossings from 2004 to 2014 as observed by the Cassini spacecraft. We find that Saturn's bow shock exhibits characteristics akin to both terrestrial and astrophysical regimes (MA of order 100), which is principally controlled by the upstream magnetic field strength. Moreover, we determined the θBn of each crossing to show that Saturn's (dayside) bow shock is predominantly quasi-perpendicular by virtue of the Parker spiral at 10 AU. Our results suggest a strong dependence on MA in controlling the onset of physical mechanisms in collisionless shocks, particularly nontime stationarity and variability. We anticipate that our comprehensive assessment will yield deeper insight into high MA collisionless shocks and provide a broader scope for understanding the structures and mechanisms of collisionless shocks.

  8. High flux solar energy transformation

    DOEpatents

    Winston, Roland; Gleckman, Philip L.; O'Gallagher, Joseph J.

    1991-04-09

    Disclosed are multi-stage systems for high flux transformation of solar energy allowing for uniform solar intensification by a factor of 60,000 suns or more. Preferred systems employ a focusing mirror as a primary concentrative device and a non-imaging concentrator as a secondary concentrative device with concentrative capacities of primary and secondary stages selected to provide for net solar flux intensification of greater than 2000 over 95 percent of the concentration area. Systems of the invention are readily applied as energy sources for laser pumping and in other photothermal energy utilization processes.

  9. High flux solar energy transformation

    DOEpatents

    Winston, R.; Gleckman, P.L.; O'Gallagher, J.J.

    1991-04-09

    Disclosed are multi-stage systems for high flux transformation of solar energy allowing for uniform solar intensification by a factor of 60,000 suns or more. Preferred systems employ a focusing mirror as a primary concentrative device and a non-imaging concentrator as a secondary concentrative device with concentrative capacities of primary and secondary stages selected to provide for net solar flux intensification of greater than 2000 over 95 percent of the concentration area. Systems of the invention are readily applied as energy sources for laser pumping and in other photothermal energy utilization processes. 7 figures.

  10. Real-time, high-resolution x-ray diffraction measurements on shocked crystals at a synchrotron facility

    NASA Astrophysics Data System (ADS)

    Gupta, Y. M.; Turneaure, Stefan J.; Perkins, K.; Zimmerman, K.; Arganbright, N.; Shen, G.; Chow, P.

    2012-12-01

    The Advanced Photon Source (APS) at Argonne National Laboratory was used to obtain real-time, high-resolution x-ray diffraction measurements to determine the microscopic response of shock-compressed single crystals. Disk shaped samples were subjected to plane shock wave compression by impacting them with half-inch diameter, flat-faced projectiles. The projectiles were accelerated to velocities ranging between 300 and 1200 m/s using a compact powder gun designed specifically for use at a synchrotron facility. The experiments were designed to keep the sample probed volume under uniaxial strain and constant stress for a duration longer than the 153.4 ns spacing between x-ray bunches. X-rays from a single pulse (<100 ps duration) out of the periodic x-ray pulses emitted by the synchrotron were used for the diffraction measurements. A synchronization and x-ray detection technique was developed to ensure that the measured signal was obtained unambiguously from the desired x-ray pulse incident on the sample while the sample was in a constant uniaxial strain state. The synchronization and x-ray detection techniques described can be used for a variety of x-ray measurements on shock compressed solids and liquids at the APS. Detailed procedures for applying the Bragg-Brentano parafocusing approach to single crystals at the APS are presented. Analytic developments to determine the effects of crystal substructure and non-ideal geometry on the diffraction pattern position and shape are presented. Representative real-time x-ray diffraction data, indicating shock-induced microstructural changes, are presented for a shock-compressed Al(111) sample. The experimental developments presented here provided, in part, the impetus for the Dynamic Compression Sector (DCS) currently under development at the APS. Both the synchronization/x-ray detection methods and the analysis equations for high-resolution single crystal x-ray diffraction can be used at the DCS.

  11. Extraterrestrial high energy neutrino fluxes

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1979-01-01

    Using the most recent cosmic ray spectra up to 2x10 to the 20th power eV, production spectra of high energy neutrinos from cosmic ray interactions with interstellar gas and extragalactic interactions of ultrahigh energy cosmic rays with 3K universal background photons are presented and discussed. Estimates of the fluxes from cosmic diffuse sources and the nearby quasar 3C273 are made using the generic relationship between secondary neutrinos and gammas and using recent gamma ray satellite data. These gamma ray data provide important upper limits on cosmological neutrinos. Quantitative estimates of the observability of high energy neutrinos from the inner galaxy and 3C273 above atmospheric background for a DUMAND type detector are discussed in the context of the Weinberg-Salam model with sq sin theta omega = 0.2 and including the atmospheric background from the decay of charmed mesons. Constraints on cosmological high energy neutrino production models are also discussed. It appears that important high energy neutrino astronomy may be possible with DUMAND, but very long observing times are required.

  12. High Energy Astrophysics Program (HEAP)

    NASA Technical Reports Server (NTRS)

    Angelini, Lorella; Corcoran, Michael; Drake, Stephen; McGlynn, Thomas A.; Snowden, Stephen; Mukai, Koji; Cannizzo, John; Lochner, James; Rots, Arnold; Christian, Eric; Barthelmy, Scott; Palmer, David; Mitchell, John; Esposito, Joseph; Sreekumar, P.; Hua, Xin-Min; Mandzhavidze, Natalie; Chan, Kai-Wing; Soong, Yang; Barrett, Paul

    1998-01-01

    This report reviews activities performed by the members of the USRA contract team during the 6 months of the reporting period and projected activities during the coming 6 months. Activities take place at the Goddard Space Flight Center, within the Laboratory for High Energy Astrophysics. Developments concern instrumentation, observation, data analysis, and theoretical work in astrophysics. Supported missions include advanced Satellite for Cosmology and Astrophysics (ASCA), X-Ray Timing Experiment (XTE), X-Ray Spectrometer (XRS), Astro-E, High Energy Astrophysics Science Archive Research Center (HEASARC) and others.

  13. High Energy Astrophysics Program (HEAP)

    NASA Technical Reports Server (NTRS)

    Angelini, L.; Holdridge, David V.; Norris, J. (Technical Monitor)

    1998-01-01

    This report reviews activities performed by members of the USRA contract team during the six months of the reporting period and projected activities during the coming six months. Activities take place at the Goddard Space Flight Center, within the Laboratory for High Energy Astrophysics. Developments concern instrumentation, observation, data analysis, and theoretical work in Astrophysics Missions supported include: Advanced Satellite for Cosmology and Astrophysics (ASCA), X-ray Timing Experiment (XTE), X-ray Spectrometer (XRS), Astro-E, High Energy Astrophysics Science Archive Research Center (HEASARC), and others.

  14. AB032. A systematic review (meta-analysis): low energy shock wave improves erectile function

    PubMed Central

    Lue, Tom F.

    2016-01-01

    Background As a novel therapeutic method for erectile dysfunction (ED), the Low Energy Shock Wave (LESW) has been applied in the clinical setting recently. We feel that a summary of the current literature and a systematic review to evaluate the therapeutic efficacy of LESW for ED would be helpful for physicians who are interested in using this modality to treat patients. Methods A comprehensive search of the PubMed and EMBASE databases to November 2015 was performed. Studies reporting on patients with ED treated by LESW were included. The international index of erectile function (IIEF) score and Erection Hardness Score (EHS) were the most commonly used tools to evaluate the therapeutic efficacy of LESW. Results There were 14 studies including 806 patients from 2005 to 2015. Seven of the 14 studies were randomized controlled trials (RCTs). In these studies, the setup parameters of LESW and the protocols of treatment were in variation. The meta-analysis revealed that LESW could improve IIEF score (MD =2.00; 95% CI, 0.99–3.00; P<0.0001) and EHS score (RD =0.16; 95% CI, 0.03–0.28; P=0.01) significantly. The therapeutic efficacy could last at least three months. The patients with mild-moderate ED or without comorbidities had better therapeutic efficacy after treatment than patients with more severe ED or comorbidities. The energy density of LESW treatment was closely related to its clinical outcome, especially on IIEF improvement. More frequent treatment or longer treatment course did not improve IIEF score. Conclusions Studies of LESW for ED patients increased sharply in recent years. Most of these studies presented encouraging results, regardless of variation in LESW setup parameters or treatment protocols. These studies suggest that LESW could significantly improve the IIEF and EHS score of ED patients. The publication of robust evidence from additional randomized controlled trials and longer-term follow-up would provide us more confidence regarding utilization

  15. Observations of low-energy electrons upstream of the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Reasoner, D. L.

    1974-01-01

    Observations of electron fluxes with a lunar-based electron spectrometer when the moon was upstream of the earth have shown that a subset of observed fluxes are strongly controlled by the interplanetary magnetic field direction. The fluxes occur only when the IMF lines connect back to the earth's bow shock. Observed densities and temperatures were in the ranges 2-4 x 0,001/cu cm and 1.7-2.8 x 1,000,000 K. It is shown that these electrons can account for increases in effective solar wind electron temperatures on bow-shock connected field lines which have been observed previously by other investigators. It is further shown that if a model of the bow shock with an electrostatic potential barrier is assumed, the potential can be estimated to be 500 volts.

  16. Aerothermodynamic heating due to shock wave/laminar boundary-layer interactions in high-enthalpy hypersonic flow

    NASA Technical Reports Server (NTRS)

    Hackett, Charles M.

    1993-01-01

    The interaction between a swept shock wave and a laminar boundary layer was investigated experimentally in high-enthalpy hypersonic flow. The effect of high-temperature, real gas physics on the interaction was examined by conducting tests in air and helium. Heat transfer measurements were made on the surface of a flat plate and a shock-generating fin using thin-film resistance sensors for fin incidence angles of 0, 5, and 10 deg at Mach numbers of 6.9 in air and 7.2 in helium. The experiments were conducted in the NASA HYPULSE expansion tube, an impulse-type facility capable of generating high-enthalpy, high-velocity flow with freestream levels of dissociated species that are particularly low. The measurements indicate that the swept shock wave creates high local heat transfer levels in the interaction region, with the highest heating found in the strongest interaction. The maximum measured heating rates in the interaction are order of magnitude greater than laminar flat plate boundary layer heating levels at the same location.

  17. The design of high-resolution upwind shock-capturing methods

    SciTech Connect

    Rider, W.J.

    1992-06-01

    The design and construction of high-resolution upwind shock-capturing methods is an effective means of solving conservation laws of physics numerically. In the past, the design of such methods was generally categorized into several distinct methods. This work shows how these methods can be viewed in a unified manner. A generalized flux-corrected transport (FCT) algorithm is shown to be total variation diminishing (TVD) under some conditions. The new algorithm has improved properties from the standpoint of use and analysis. This is shown to be especially important for systems of equations. The new formulation allows Riemann solvers to be used effectively with FCT methods. This directly leads to a geometric analog to symmetric TVD and FCT methods that is developed and expanded upon. This unifies these methods with high-order Godunov (HOG) methods. Two new variants of this are derived and shown to be uniformly non-oscillatory. Limiters are an effective means of designing these types of methods. More general classes of limiters are discussed with extensions to a wider class of schemes. Flux-corrected transport and total variation bounded (TVB) limiters are discussed, modified, and expanded. Two new classes of limiters are described: s-limiters and generalized average limiters. The recently defined ULTIMATE limiter is analyzed within the framework of the other limiters. The benefits of relaxing strict constraints on the limiters such as TVD requirements are also discussed. For coarse grids, limiters such as the TVB and the generalized average with bias improve resolution considerably. Lastly, the question of whether the polynomial reconstruction technique used in a HOG method should be based on cell-averages or point-values is studied.

  18. Lhermitte's sign, electric shock sensations and high dose ecstasy consumption: preliminary findings.

    PubMed

    Boland, B; Mitcheson, L; Wolff, K

    2010-02-01

    The objectives of this study were to perform a preliminary investigation into the nature of electric shock-like experiences reported in association with the use of ecstasy tablets thought to contain methylenedioxymethamphetamines (MDMA). This included exploration of reports of electric shock-like experiences from the user's perspectives and identification of other variables that may be associated with their development. Furthermore we aimed to examine whether the well-recognised electric shock-like symptom, Lhermitte's sign (LS), is associated with ecstasy tablet use in some drug users. A single measure, cross-sectional survey was used incorporating mixed qualitative and quantitative methodology. A select group of ecstasy users (n = 35) recruited through a dance, music and lifestyle magazine completed a telephone interview. Lifetime prevalence of LS in the study population was 18% (n = 6). Development of LS was associated with use of more ecstasy tablets before a typical incident. This study indicates a relationship may exist between the use of ecstasy tablets and LS. The relationship may be dose dependent. The majority of the study population used other substances including alcohol when experiencing electrical shock sensations. LS may explain only a proportion of all electrical shock experiences among ecstasy users. PMID:19240087

  19. Comparative study of high-resolution shock-capturing schemes for a real gas

    NASA Technical Reports Server (NTRS)

    Montagne, J.-L.; Yee, H. C.; Vinokur, M.

    1988-01-01

    Recently developed second-order explicit shock-capturing methods, in conjunction with generalized flux-vector splittings, and a generalized approximate Riemann solver for a real gas are studied. The comparisons are made on different one-dimensional Riemann (shock-tube) problems for equilibrium air with various ranges of Mach numbers, densities and pressures. Six different Riemann problems are considered. These tests provide a check on the validity of the generalized formulas, since theoretical prediction of their properties appears to be difficult because of the non-analytical form of the state equation. The numerical results in the supersonic and low-hypersonic regimes indicate that these produce good shock-capturing capability and that the shock resolution is only slightly affected by the state equation of equilibrium air. The difference in shock resolution between the various methods varies slightly from one Riemann problem to the other, but the overall accuracy is very similar. For the one-dimensional case, the relative efficiency in terms of operation count for the different methods is within 30 percent. The main difference between the methods lies in their versatility in being extended to multidimensional problems with efficient implicit solution procedures.

  20. Comparative study of high-resolution shock-capturing schemes for a real gas

    NASA Technical Reports Server (NTRS)

    Montagne, J.-L.; Yee, H. C.; Vinokur, M.

    1987-01-01

    Recently developed second-order explicit shock-capturing methods, in conjunction with generalized flux-vector splittings, and a generalized approximate Riemann solver for a real gas are studied. The comparisons are made on different one-dimensional Riemann (shock-tube) problems for equilibrium air with various ranges of Mach numbers, densities and pressures. Six different Riemann problems are considered. These tests provide a check on the validity of the generalized formulas, since theoretical prediction of their properties appears to be difficult because of the non-analytical form of the state equation. The numerical results in the supersonic and low-hypersonic regimes indicate that these produce good shock-capturing capability and that the shock resolution is only slightly affected by the state equation of equilibrium air. The difference in shock resolution between the various methods varies slightly from one Riemann problem to the other, but the overall accuracy is very similar. For the one-dimensional case, the relative efficiency in terms of operation count for the different methods is within 30%. The main difference between the methods lies in their versatility in being extended to multidimensional problems with efficient implicit solution procedures.

  1. Higher Energy Plasma Ions found near the Termination Shock: Analyses of Voyager 2 Data in the Heliosheath and in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Intriligator, Devrie S.; Intriligator, James; Miller, W. David; Webber, William R.; Decker, Robert B.

    2010-01-01

    We have found in the Voyager 2 (V2) plasma science data in the heliosheath (HS) near the termination shock (TS) high-energy ions (HEIs) in addition to the bulk plasma convective flow ions. The HEI detections temporally coincide with increased V2 plasma wave subsystem (PWS) activity in "event A"h of Gurnett and Kurth. Maxwellian fits to HEI detections indicate the HEIs are moving radially anti -Sunward with a proton speed of 600 km/s, a density of 10(exp -4) (exp -3), and a thermal speed of 10 km/s. The heliosheath bulk convective protons have a speed of 204 km/s, a density of 0.0029 cm(exp -3), and a thermal speed of 26.7 km/s. The HEI flux and ram pressure are approximately 10% and 30% of those of the bulk HS flow. Since the HEI speed is both close to twice the solar wind speed and independent of the heliosheath bulk plasma speed, the HEIs may be detections of pickup protons formed in the solar wind and convected through the TS. The HEIs also are reminiscent of the pickup protons upstream of the Mars bow shock where their energy also was independent of the bulk plasma speed and attributed to multiple reflections off the Mars bow shock. Gurnett and Kurth 's (2008) event A enhanced PWS activity may be generated by a two ]stream instability from the interaction of these HEIs with the heliosheath bulk plasma ions. We present our findings, discuss their implications, and also present alternative interpretations.

  2. High-energy emission from the eclipsing millisecond pulsar PSR 1957+20

    NASA Technical Reports Server (NTRS)

    Arons, Jonathan; Tavani, Marco

    1993-01-01

    The properties of the high-energy emission expected from the eclipsing millisecond pulsar system PSR 1957+20 are investigated. Emission is considered by both the relativistic shock produced by the pulsar wind in the nebula surrounding the binary and by the shock constraining the mass outflow from the companion star of PSR 1957+20. On the basis of the results of microscopic plasma physical models of relativistic shocks it is suggested that the high-energy radiation is produced in the range from X-rays to MeV gamma rays in the binary and in the range from 0.01 eV to about 40 keV in the nebula. Doppler boost of the emission in the radiating wind suggests the flux should vary on the orbital time scale, with the largest flux observed roughly coincident with the pulsar's radio eclipse.

  3. High-energy neutron dosimetry

    NASA Astrophysics Data System (ADS)

    Sutton, Michele Rhea

    2001-12-01

    Fluence-to-dose conversion coefficients for the radiation protection quantity effective dose were calculated for neutrons, photons and protons with energies up to 2 GeV using the MCNPX code. The calculations were performed using the Pacific Northwest National Laboratory versions of the MIRD-V male and female anthropomorphic phantoms modified to include the skin and esophagus. The latest high-energy neutron evaluated cross-section libraries and the recommendations given in ICRP Publication 60 and ICRP Publication 74 were utilized to perform the calculations. Sets of fluence-to- effective dose conversion coefficients are given for anterior-posterior, posterior-anterior, left-lateral, right-lateral and rotational irradiation geometries. This is the first set of dose conversion coefficients over this energy range calculated for the L-LAT irradiation geometry. A unique set of high-energy neutron depth-dose benchmark experiments were performed at the Los Alamos Neutron Science Center/Weapons Neutron Research (LANSCE/WNR) complex. The experiments consisted of filtered neutron beams with energies up to 800 MeV impinging on a 30 x 30 x 30 cm3 tissue-equivalent phantom. The absorbed dose was measured in the phantom at various depths with tissue-equivalent ion chambers. The phantom and the experimental set-up were modeled using MCNPX. Comparisons of the experimental and computational depth- dose distributions indicate that the absorbed dose calculated by MCNPX is within 13% for neutrons with energies up to 750 MeV. This experiment will serve as a benchmark experiment for the testing of high-energy radiation transport codes for the international radiation protection community.

  4. High energy gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Fichtel, Carl E.

    1987-01-01

    High energy gamma ray astronomy has evolved with the space age. Nonexistent twenty-five years ago, there is now a general sketch of the gamma ray sky which should develop into a detailed picture with the results expected to be forthcoming over the next decade. The galactic plane is the dominant feature of the gamma ray sky, the longitude and latitude distribution being generally correlated with galactic structural features including the spiral arms. Two molecular clouds were already seen. Two of the three strongest gamma ray sources are pulsars. The highly variable X-ray source Cygnus X-3 was seen at one time, but not another in the 100 MeV region, and it was also observed at very high energies. Beyond the Milky Way Galaxy, there is seen a diffuse radiation, whose origin remains uncertain, as well as at least one quasar, 3C 273. Looking to the future, the satellite opportunities for high energy gamma ray astronomy in the near term are the GAMMA-I planned to be launched in late 1987 and the Gamma Ray Observatory, scheduled for launch in 1990. The Gamma Ray Observatory will carry a total of four instruments covering the entire energy range from 30,000 eV to 3 x 10 to the 10th eV with over an order of magnitude increase in sensitivity relative to previous satellite instruments.

  5. High energy density electrochemical cell

    NASA Technical Reports Server (NTRS)

    Byrne, J. J.; Williams, D. L.

    1970-01-01

    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density.

  6. Temperature-dependent shock initiation of TATB-based high explosives

    SciTech Connect

    Dallman, J.C.; Wackerle, J.

    1993-10-01

    The effects of temperature on the shock sensitivity of two TATB formulations PBX 9502 and LX-17 are studied over the temperature range {minus}54{degrees}C to 252{degrees}C. The shock Hugoniot curves over this same temperature range are developed. Thermal expansion properties and porosities are used to help determine the mechanisms of thermal sensitization. Impact sensitivities over the range from ambient to 300{degrees}C are reported. Analyses of these results imply that thermal sensitization is the result of purely chemical kinetics enhancement and intracrystalline hot-spot growth. Additional results on the ambient shock sensitivity of PBX 9502 and LX-17 following thermal cycling to 252{degrees}C and back to ambient is presented.

  7. On the high correlation between storm sudden commencements and interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Park, W.; Lee, J.; Oh, S.; Yi, Y.

    2014-12-01

    Storm Sudden Commencements (SSCs) occur due to sudden compression of magnetic field and current enhancement in the magnetopause, which is generally believed to be caused by interplanetary shock. However, neither all geomagnetic storms exhibit the SSC nor all SSCs are accompanied by interplanetary shocks. In this study, we search for geomagnetic storms without SSC using the SYM-H index data which is provided by the World Data Center for Geomagnetism Kyoto (WDC Geomag, Kyoto) during the period of 1998-2010. We also investigate the physical conditions such as density and velocity of protons, IMF Bz and total field strength provided by Advanced Composition Explorer (ACE) satellite. Finally, we classify the geomagnetic storms into two groups depending on whether or not accompanied by SSC and then further classify them based on their association with interplanetary shocks. Physical characteristics of the storms in each group will briefly be discussed.

  8. Proton shock acceleration in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Marti, M.; Davies, J.; Fonseca, R. A.; Silva, L. O.; Fahlen, J.; Ren, C.; Tsung, F.; Mori, W. B.

    2003-10-01

    The formation of strong, high Mach number (2--3), electrostatic shocks by laser pulses incident on overdense plasma slabs is observed in 1 and 2-dimensional particle-in-cell simulations, for a wide range of intensities, pulse durations, target thicknesses and densities. The shocks propagate undisturbed across the plasma, accelerating the ions (protons). For dimensionless field strength parameter a_0=16 (Iλ^2 ≈ 3 × 10^20 W cm-2 μm^2, where I is intensity and λ wavelength) the highest energy protons are accelerated by the shock. A plateau in the ion spectrum provides a direct signature for shock acceleration.

  9. High-resolution PIV measurements of a transitional shock wave-boundary layer interaction

    NASA Astrophysics Data System (ADS)

    Giepman, R. H. M.; Schrijer, F. F. J.; van Oudheusden, B. W.

    2015-06-01

    This study investigates the effects of boundary layer transition on an oblique shock wave reflection. The Mach number was 1.7, the unit Reynolds number was 35 × 106 m-1, and the pressure ratio over the interaction was 1.35. Particle image velocimetry is used as the main flow diagnostics tool, supported by oil-flow and Schlieren visualizations. At these conditions, the thickness of the laminar boundary layer is only 0.2 mm, and seeding proved to be problematic as practically no seeding was recorded in the lower 40 % of the boundary layer. The top 60 % could, however, still be resolved with good accuracy and is found to be in good agreement with the compressible Blasius solution. Due to the effects of turbulent mixing, the near-wall seeding deficiency disappears when the boundary layer transitions to a turbulent state. This allowed the seeding distribution to be used as an indicator for the state of the boundary layer, permitting to obtain an approximate intermittency distribution for the boundary layer transition region. This knowledge was then used for positioning the oblique shock wave in the laminar, transitional (50 % intermittency) or turbulent region of the boundary layer. Separation is only recorded for the laminar and transitional interactions. For the laminar interaction, a large separation bubble is found, with a streamwise length of 96. The incoming boundary layer is lifted over the separation bubble and remains in a laminar state up to the impingement point of the shock wave. After the shock, transition starts and a turbulent profile is reached approximately 80-90 downstream of the shock. Under the same shock conditions, the transitional interaction displays a smaller separation bubble (43), and transition is found to be accelerated over the separation bubble.

  10. Application of the Generalized Shock-expansion Method to Inclined Bodies of Revolution Traveling at High Supersonic Airspeeds

    NASA Technical Reports Server (NTRS)

    Savin, Raymond C

    1955-01-01

    The generalized shock-expansion method is applied to obtain solutions to the flow field about pointed bodies of revolution at high supersonic airspeeds and small angles of attack. Simple explicit expressions are obtained for the surface Mach numbers and surface pressures in the special case of slender bodies. In the case of inclined cones, algebraic solutions are obtained defining the entire flow field. Experimental pressure-distribution data for cones and ogives at Mach numbers from 3 to 5 are included. (author)

  11. Laser Energy Deposition for Shock Wave Boundary Layer Control at Supersonic Speeds

    NASA Astrophysics Data System (ADS)

    Erdem, E.; Kontis, K.; Osuka, T.; Majima, R.; Tamba, T.; Sasoh, Akihiro

    Shock Wave Boundary Layer Interactions (SWBLIs) can induce separation which causes loss of a control surface effectiveness, drop of an air intake efficiency and it may be the origin of large scale fluctuations such as air-intake buzz, buffeting or fluctuating side loads in separated propulsive nozzles

  12. Molecular dissociation and shock-induced cooling in fluid nitrogen at high densities and temperatures

    NASA Technical Reports Server (NTRS)

    Radousky, H. B.; Nellis, W. J.; Ross, M.; Hamilton, D. C.; Mitchell, A. C.

    1986-01-01

    Radiative temperatures and electrical conductivities were measured for fluid nitrogen compressed dynamically to pressures of 18-90 GPa, temperatures of 4000-14,000 K, and densities of 2-3 g/cu cm. The data show a continuous phase transition above 30 GPa shock pressure and confirm that (delta-P/delta-T)v is less than 0, as indicated previously by Hugoniot equation-of-state experiments. The first observation of shock-induced cooling is also reported. The data are interpreted in terms of molecular dissociation, and the concentration of dissociated molecules is calculated as a function of density and temperature.

  13. Elucidation of the dynamics for hot-spot initiation at nonuniform interfaces of highly shocked materials

    NASA Astrophysics Data System (ADS)

    An, Qi; Zybin, Sergey V.; Goddard, William A., III; Jaramillo-Botero, Andres; Blanco, Mario; Luo, Sheng-Nian

    2011-12-01

    The fundamental processes in shock-induced instabilities of materials remain obscure, particularly for detonation of energetic materials. We simulated these processes at the atomic scale on a realistic model of a polymer-bonded explosive (3,695,375 atoms/cell) and observed that a hot spot forms at the nonuniform interface, arising from shear relaxation that results in shear along the interface that leads to a large temperature increase that persists long after the shock front has passed the interface. For energetic materials this temperature increase is coupled to chemical reactions that lead to detonation. We show that decreasing the density of the binder eliminates the hot spot.

  14. High-accuracy deterministic solution of the Boltzmann equation for the shock wave structure

    NASA Astrophysics Data System (ADS)

    Malkov, E. A.; Bondar, Ye. A.; Kokhanchik, A. A.; Poleshkin, S. O.; Ivanov, M. S.

    2015-07-01

    A new deterministic method of solving the Boltzmann equation has been proposed. The method has been employed in numerical studies of the plane shock wave structure in a hard sphere gas. Results for Mach numbers and have been compared with predictions of the direct simulation Monte Carlo (DSMC) method, which has been used to obtain the reference solution. Particular attention in estimating the solution accuracy has been paid to a fine structural effect: the presence of a total temperature peak exceeding the temperature value further downstream. The results of solving the Boltzmann equation for the shock wave structure are in excellent agreement with the DSMC predictions.

  15. Precision equation of state measurements on hydrocarbons in the high energy density regime

    NASA Astrophysics Data System (ADS)

    Barrios Garcia, Maria Alejandra

    The equation of state (EOS) of materials at extreme temperatures and pressures is of interest to astrophysics, high-energy-density physics, and inertial confinement fusion (ICF). The behavior of hydrocarbon materials at high-pressures (>1 Mbar) is essential to the understanding of ablator materials for ICF ignition targets. The EOS measurements on CHX presented here provide benchmark behavior of hydrocarbons under extreme conditions and the effect of stoichiometry (i.e. C:H ratio) on that behavior. Advances in diagnostics and analysis have made it possible to perform highly accurate measurements of shock velocity to ˜1% precision in transparent materials. This refines the impedance-match (IM) technique for laser-driven shock experiments producing precise EOS data at extreme pressures using a transparent standard such as alpha-quartz. The OMEGA laser was used to produce principal (single-shock) Hugoniot EOS measurements on polystyrene (CH), polypropylene (CH2), Glow-Discharge-Polymer (GDP) (C43H56O), and Germanium-doped GDP at shock pressures of 1--10 Mbar, with an alpha-quartz standard. This precision data tightly constrains the Hugoniot behavior of these hydrocarbons, even with the inclusion of systematic uncertainties inherent in the IM technique. A novel target design providing double-shock (re-shock) measurements along with principal Hugoniot data is presented. Results of the single-and double-shock experiments on these hydrocarbons are presented and compared to various EOS models. Temperature measurements are presented for CH and CH2; measuring both the thermal and kinematic behavior of these materials provides their complete shock EOS. Reflectance measurements on CH and CH2 show that both hydrocarbons transition from transparent insulators to reflecting conductors at pressures of 1 to 2 Mbar.

  16. On the deficit problem of mass and energy of solar coronal mass ejections connected with interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Ivanchuk, V. I.; Pishkalo, N. I.

    1995-01-01

    Mean values of a number of parameters of the most powerful coronal mass ejections (CMEs) and interplanetary shocks generated by these ejections are estimated using an analysis of data obtained by the cosmic coronagraphs and spacecrafts, and geomagnetic storm measurements. It was payed attention that the shock mass and mechanical energy, averaging 5 x 10(exp 16) grm and 2 x 10(exp 32) erg respectively, are nearly 10 times larger than corresponding parameters of the ejections. So, the CME energy deficit problem seems to exist really. To solve this problem one can make an assumption that the process of the mass and energy growth of CMEs during their propagation out of the Sun observed in the solar corona is continued in supercorona too up to distances of 10-30 solar radii. This assumption is confirmed by the data analysis of five events observed using zodiacal light photometers of the HELIOS- I and HELIOS-2 spacecrafts. The mass growth rate is estimated to be equal to (1-7) x 10(exp 11) grm/sec. It is concluded that the CME contribution to mass and energy flows in the solar winds probably, is larger enough than the value of 3-5% adopted usually.

  17. Gamma-ray bursts and collisionless shocks

    NASA Astrophysics Data System (ADS)

    Waxman, E.

    2006-12-01

    Particle acceleration in collisionless shocks is believed to be responsible for the production of cosmic-rays over a wide range of energies, from a few GeV to > 1020 eV, as well as for the non-thermal emission of radiation from a wide variety of high energy astrophysical sources. A theory of collisionless shocks based on first principles does not, however, exist. Observations of γ-ray burst (GRB) 'afterglows' provide a unique opportunity for diagnosing the physics of relativistic collisionless shocks. Most GRBs are believed to be associated with explosions of massive stars. Their 'afterglows', delayed low energy emission following the prompt burst of γ-rays, are well accounted for by a model in which afterglow radiation is due to synchrotron emission of electrons accelerated in relativistic collisionless shock waves driven by the explosion into the surrounding plasma. Within the framework of this model, some striking characteristics of collisionless relativistic shocks are implied. These include the generation of downstream magnetic fields with energy density exceeding that of the upstream field by ~8 orders of magnitude, the survival of this strong field at distances ~1010 skin-depths downstream of the shock and the acceleration of particles to a power-law energy spectrum, d log n/d logɛ ap -2, possibly extending to 1020 eV. I review in this talk the phenomenological considerations, based on which these characteristics are inferred, and the challenges posed to our current models of particle acceleration and magnetic field generation in collisionless shocks. Some recent theoretical results derived based on the assumption of a self-similar shock structure are briefly discussed. Invited review presented at the 33rd annual European Physical Society Conference, Rome, 2006.

  18. A numerical study of fundamental shock noise mechanisms. Ph.D. Thesis - Cornell Univ.

    NASA Technical Reports Server (NTRS)

    Meadows, Kristine R.

    1995-01-01

    The results of this thesis demonstrate that direct numerical simulation can predict sound generation in unsteady aerodynamic flows containing shock waves. Shock waves can be significant sources of sound in high speed jet flows, on helicopter blades, and in supersonic combustion inlets. Direct computation of sound permits the prediction of noise levels in the preliminary design stage and can be used as a tool to focus experimental studies, thereby reducing cost and increasing the probability of a successfully quiet product in less time. This thesis reveals and investigates two mechanisms fundamental to sound generation by shocked flows: shock motion and shock deformation. Shock motion is modeled by the interaction of a sound wave with a shock. During the interaction, the shock wave begins to move and the sound pressure is amplified as the wave passes through the shock. The numerical approach presented in this thesis is validated by the comparison of results obtained in a quasi-one dimensional simulation with linear theory. Analysis of the perturbation energy demonstrated for the first time that acoustic energy is generated by the interaction. Shock deformation is investigated by the numerical simulation of a ring vortex interacting with a shock. This interaction models the passage of turbulent structures through the shock wave. The simulation demonstrates that both acoustic waves and contact surfaces are generated downstream during the interaction. Analysis demonstrates that the acoustic wave spreads cylindrically, that the sound intensity is highly directional, and that the sound pressure level increases significantly with increasing shock strength. The effect of shock strength on sound pressure level is consistent with experimental observations of shock noise, indicating that the interaction of a ring vortex with a shock wave correctly models a dominant mechanism of shock noise generation.

  19. Polymyxin B-immobilized fiber hemoperfusion in a high school football player with septic shock caused by osteitis pubis.

    PubMed

    Nakamura, Tsukasa; Sato, Eiichi; Fujiwara, Nobuharu; Kawagoe, Yasuhiro; Egawa, Yoshinaga; Ueda, Yoshihiko; Koide, Hikaru

    2011-01-01

    A 17-year-old male high school football player treated by polymyxin B-immobilized fiber (PMX-F) hemoperfusion for mild-moderate septic shock caused by osteitis pubis is described in this study. He was admitted for inguinal pain, gait disturbance, and high fever (40.6°C). His white blood cell (WBC) count and C-reactive protein (CRP), endotoxin, and procalcitonin (PCT) levels were significantly elevated. His blood pressure was 76/46 mm Hg. Magnetic resonance imaging showed bone and muscle injury at the pubic symphysis. Septic shock with high blood endotoxin and PCT concentrations was diagnosed, and the patient was treated with antibiotics, γ-globulin, and dopamine on the admission day. However, the septic shock did not improve. On day 3, we performed direct hemoperfusion twice using a PMX-F column. After the second PMX-F treatment, the patient's temperature decreased to 37.0°C, and his WBC count, CRP levels, blood endotoxin, and PCT levels decreased. The inguinal pain diminished, and the patient's blood pressure increased to 112/76 mm Hg. He was discharged on day 10 after admission. This case reflects association of PMX-F with decreased endotoxin, PCT, and CRP, suggesting the association of PMX-F with clinical improvement in mild-moderate sepsis in a young athlete. PMID:21817894

  20. CRYSTALLINE BEAMS AT HIGH ENERGIES.

    SciTech Connect

    WEI, J.; OKAMOTO, H.; YURI, Y.; SESSLER, A.; MACHIDA, S.

    2006-06-23

    Previously it was shown that by crystallizing each of the two counter-circulating beams, a much larger beam-beam tune shift can be tolerated during the beam-beam collisions; thus a higher luminosity can be reached for colliding beams [1]. On the other hand, crystalline beams can only be formed at energies below the transition energy ({gamma}{sub T}) of the accelerators [2]. In this paper, we investigate the formation of crystals in a high-{gamma}{sub T} lattice that also satisfies the maintenance condition for a crystalline beam [3].