Shock compression experiments on Lithium Deuteride (LiD) single crystals

Science.gov (United States)

Knudson, M. D.; Desjarlais, M. P.; Lemke, R. W.

2016-12-01

Shock compression experiments in the few hundred GPa (multi-Mbar) regime were performed on Lithium Deuteride single crystals. This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17-32 km/s. Measurements included pressure, density, and temperature between ˜190 and 570 GPa along the Principal Hugoniot—the locus of end states achievable through compression by large amplitude shock waves—as well as pressure and density of reshock states up to ˜920 GPa. The experimental measurements are compared with density functional theory calculations, tabular equation of state models, and legacy nuclear driven results that have been reanalyzed using modern equations of state for the shock wave standards used in the experiments.

Magnetic Diagnostics on the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Hutchinson, T. M.; Weber, T. E.; Boguski, J. C.; Intrator, T. P.; Smith, R. J.; Dunn, J. P.

2013-10-01

The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory was built to investigate the physics of high-Alfvénic, supercritical, magnetized shocks through the acceleration and subsequent stagnation of a Field Reversed Configuration (FRC) plasmoid against a magnetic mirror and/or plasma target. An array of high-bandwidth, multi-axis, robust, internal magnetic probes has been constructed to characterize flux compression ratios, instability formation, and turbulent macro-scale features of the post-shock plasma. The mirror magnet is mounted on a linear translation stage, providing a capability to axially move the shock layer through the probe field of view. An independent, external probe array also provides conventional information on the FRC shape, velocity, and total pressure during the formation and acceleration phases. Probe design, characterization, configuration, and initial results are presented. This work is supported by the DOE OFES and NNSA under LANS contract DE-AC52-06NA25369. LA-UR-13-25189.

BOW SHOCK FRAGMENTATION DRIVEN BY A THERMAL INSTABILITY IN LABORATORY ASTROPHYSICS EXPERIMENTS

Energy Technology Data Exchange (ETDEWEB)

Suzuki-Vidal, F.; Lebedev, S. V.; Pickworth, L. A.; Swadling, G. F.; Skidmore, J.; Hall, G. N.; Bennett, M.; Bland, S. N.; Burdiak, G.; De Grouchy, P.; Music, J.; Suttle, L. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom); Ciardi, A. [Sorbonne Universités, UPMC Univ. Paris 6, UMR 8112, LERMA, F-75005, Paris (France); Rodriguez, R.; Gil, J. M.; Espinosa, G. [Departamento de Fisica de la Universidad de Las Palmas de Gran Canaria, E-35017 Las Palmas de Gran Canaria (Spain); Hartigan, P. [Department of Physics and Astronomy, Rice University, 6100 S. Main, Houston, TX 77521-1892 (United States); Hansen, E.; Frank, A., E-mail: f.suzuki@imperial.ac.uk [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)

2015-12-20

The role of radiative cooling during the evolution of a bow shock was studied in laboratory-astrophysics experiments that are scalable to bow shocks present in jets from young stellar objects. The laboratory bow shock is formed during the collision of two counterstreaming, supersonic plasma jets produced by an opposing pair of radial foil Z-pinches driven by the current pulse from the MAGPIE pulsed-power generator. The jets have different flow velocities in the laboratory frame, and the experiments are driven over many times the characteristic cooling timescale. The initially smooth bow shock rapidly develops small-scale nonuniformities over temporal and spatial scales that are consistent with a thermal instability triggered by strong radiative cooling in the shock. The growth of these perturbations eventually results in a global fragmentation of the bow shock front. The formation of a thermal instability is supported by analysis of the plasma cooling function calculated for the experimental conditions with the radiative packages ABAKO/RAPCAL.

Advances in shock timing experiments on the National Ignition Facility

International Nuclear Information System (INIS)

Robey, H F; Celliers, P M; Moody, J D; Sater, J; Parham, T; Kozioziemski, B; Dylla- Spears, R; Ross, J S; LePape, S; Ralph, J E; Hohenberger, M; Dewald, E L; Berzak Hopkins, L; Kroll, J J; Yoxall, B E; Hamza, A V; Landen, O L; Edwards, M J; Boehly, T R; Nikroo, A

2016-01-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion (ICF) implosions were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. (paper)

Advances in shock timing experiments on the National Ignition Facility

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2016-03-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion (ICF) implosions were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique.

The Transitional Experience: An Alternative View of Culture Shock

Science.gov (United States)

Adler, Peter S.

1975-01-01

This article contended that the problems and frustrations encountered in the culture shock process are important to an understanding of change and movement experiences, and that such transitional experiences can be the source of higher levels of personality development. (Author/RK)

Pressurized-thermal-shock experiments with thick vessels

International Nuclear Information System (INIS)

Bryan, R.H.; Nanstad, R.K.; Merkle, J.G.; Robinson, G.C.; Whitman, G.D.

1986-01-01

Information is provided on the series of pressurized-thermal-shock experiments at the Oak Ridge National Laboratory, motivated by a concern for the behavior of flaws in reactor pressure vessels having welds or shells exhibiting low upper-shelf Charpy impact energies, approx. 68J or less

Overview and recent progress of the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Weber, T. E.; Intrator, T. P.; Smith, R. J.; Hutchinson, T. M.; Boguski, J. C.; Sears, J. A.; Swan, H. O.; Gao, K. W.; Chapdelaine, L. J.; Winske, D.; Dunn, J. P.

2013-10-01

The Magnetized Shock Experiment (MSX) has been constructed to study the physics of super-Alfvènic, supercritical, magnetized shocks. Exhibiting transitional length and time scales much smaller than can be produced through collisional processes, these shocks are observed to create non-thermal distributions, amplify magnetic fields, and accelerate particles to relativistic velocities. Shocks are produced through the acceleration and subsequent stagnation of Field Reversed Configuration (FRC) plasmoids against a high-flux magnetic mirror with a conducting boundary or a plasma target with embedded field. Adjustable shock velocity, density, and magnetic geometry (B parallel, perpendicular, or oblique to k) provide unique access to a wide range of dimensionless parameters relevant to astrophysical shocks. Information regarding the experimental configuration, diagnostics suite, recent simulations, experimental results, and physics goals will be presented. This work is supported by DOE OFES and NNSA under LANS contract DE-AC52-06NA25369 Approved for Public Release: LA-UR-13-24859.

One surgeon's Army experience with "wound shock" from Pearl Harbor to the present.

Science.gov (United States)

Hardaway, Robert M

2009-09-01

The Army has had extensive experience in the study and treatment of shock, beginning with the American Civil War and continuing to the present. This is the story of one Army surgeon's experience, both in research and treatment of shock, from Pearl Harbor to the present.

Optimal Design of Shock Tube Experiments for Parameter Inference

KAUST Repository

Bisetti, Fabrizio

2014-01-06

We develop a Bayesian framework for the optimal experimental design of the shock tube experiments which are being carried out at the KAUST Clean Combustion Research Center. The unknown parameters are the pre-exponential parameters and the activation energies in the reaction rate expressions. The control parameters are the initial mixture composition and the temperature. The approach is based on first building a polynomial based surrogate model for the observables relevant to the shock tube experiments. Based on these surrogates, a novel MAP based approach is used to estimate the expected information gain in the proposed experiments, and to select the best experimental set-ups yielding the optimal expected information gains. The validity of the approach is tested using synthetic data generated by sampling the PC surrogate. We finally outline a methodology for validation using actual laboratory experiments, and extending experimental design methodology to the cases where the control parameters are noisy.

Material Evidence for Ocean Impact from Shock-Metamorphic Experiments

Science.gov (United States)

Miura, Y.; Takayama, K.; Iancu, O. G.

1993-07-01

Continental impact reveals an excavated crater that has few fresh fine ejecta showing major high shock metamorphism due to weathering [1]. A giant ocean impact rarely remains as an excavated crater mainly due to crushing by dynamic plate-tectonic movements on the crust [2]. However, all impact materials, including fine-grained ejecta, can be obtained with artificial impact experiments [3]. The purpose of this study is to discuss material evidence for ocean impact based on shock-metamorphic experiments. Artificial impact experiments indicate that fine shocked quartz (SQ) aggregates can be formed on several target rocks (Table 1) [1]. It is found in Table 1 that (1) the largest-density deviation of SQ grain is found not at the wall-rock or the impact crater but at fine-grained ejecta, and (2) silica-poor rocks of basalt, gabbro, and anorthosite can also make fine SQ aggregates by impact. Table 1, which appears here in the hard copy, shows formations of fine shocked quartz aggregates from ocean-floor rocks of basalt, gabbroic anorthosite, and granite [3]. An asteroid (about 10 km across) hits the Earth ~65 m.y. ago [4] to result in global catastrophe by titanic explosion and climate change. But shocked quartz grains found in the K/T boundary layer were considered to come from crystalline continental rocks [5]. The present result as listed in Table 1 indicates that fine SQ aggregates can also be formed at sea-floor basaltic and gabbroic rocks [3]. The present result of formation of the SQ grains from sea- floor target rocks is nearly consistent with the finding of a sea-impact crater at the K/T boundary near the Caribbean [6]. Impact-induced volcanism at the K/T boundary can explained by the penetration from thin ocean crust to upper mantle reservoirs, if giant impact of a 10-km- diameter asteroid hit the ocean [2,7]. The present result can explain "phreatomagmatic (magmatic vapor) explosion," which is created by abrupt boiling between high-temperature magma and cold

Shock initiation experiments on ratchet grown PBX 9502

Energy Technology Data Exchange (ETDEWEB)

Gustavsen, Richard L [Los Alamos National Laboratory; Thompson, Darla G [Los Alamos National Laboratory; Olinger, Barton W [Los Alamos National Laboratory; Deluca, Racci [Los Alamos National Laboratory; Bartram, Brian D [Los Alamos National Laboratory; Pierce, Timothy H [Los Alamos National Laboratory; Sanchez, Nathaniel J [Los Alamos National Laboratory

2010-01-01

This study compares the shock initiation behavior of PBX 9502 pressed to less than nominal density (nominal density is 1.890 {+-} 0.005 g/cm{sup 3}) with PBX 9502 pressed to nominal density and then ''ratchet grown'' to low density. PBX 9502 is an insensitive plastic bonded explosive consisting of 95 weight % dry-aminated tri-amino-tri-nitro-benzene (TATB) and 5 weight % Kel-F 800 plastic binder. ''Ratchet growth'' - an irreversible increase in specific volume - occurs when an explosive based on TATB is temperature cycled. The design of our study is as follows: PBX 9502, all from the same lot, received the following four treatments. Samples in the first group were pressed to less than nominal density. These were not ratchet grown and used as a baseline. Samples in the second group were pressed to nominal density and then ratchet grown by temperature cycling 30 times between -54 C and +80 C. Samples in the final group were pressed to nominal density and cut into 100 mm by 25.4 mm diameter cylinders. During thermal cycling the cylinders were axially constrained by a 100 psi load. Samples for shock initiation experiments were cut perpendicular (disks) and parallel (slabs) to the axial load. The four sample groups can be summarized with the terms pressed low, ratchet grown/no load, axial load/disks, and axial load/slabs. All samples were shock initiated with nearly identical inputs in plate impact experiments carried out on a gas gun. Wave profiles were measured after propagation through 3, 4, 5, and 6 mm of explosive. Side by side comparison of wave profiles from different samples is used as a measure of relative sensitivity. All reduced density samples were more shock sensitive than nominal density PBX 9502. Differences in shock sensitivity between ratchet grown and pressed to low density PBX 9502 were small, but the low density pressings are slightly more sensitive than the ratchet grown samples.

Collisionless shock experiments with lasers and observation of Weibel instabilities

Energy Technology Data Exchange (ETDEWEB)

Park, H.-S., E-mail: park1@llnl.gov; Huntington, C. M.; Fiuza, F.; Levy, M. C.; Pollock, B. B.; Remington, B. A.; Ross, J. S.; Ryutov, D. D.; Turnbull, D. P.; Weber, S. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Drake, R. P.; Kuranz, C. C. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Froula, D. H.; Rosenberg, M. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14636 (United States); Gregori, G.; Meinecke, J. [University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Koenig, M. [LULI, Ecole Polytechnique, Palaiseau (France); Kugland, N. L. [Lam Research Corporation, Fremont, California 94538 (United States); Lamb, D. Q.; Tzeferacos, P. [University of Chicago, Chicago, California 94538 (United States); and others

2015-05-15

Astrophysical collisionless shocks are common in the universe, occurring in supernova remnants, gamma ray bursts, and protostellar jets. They appear in colliding plasma flows when the mean free path for ion-ion collisions is much larger than the system size. It is believed that such shocks could be mediated via the electromagnetic Weibel instability in astrophysical environments without pre-existing magnetic fields. Here, we present laboratory experiments using high-power lasers and investigate the dynamics of high-Mach-number collisionless shock formation in two interpenetrating plasma streams. Our recent proton-probe experiments on Omega show the characteristic filamentary structures of the Weibel instability that are electromagnetic in nature with an inferred magnetization level as high as ∼1% [C. M. Huntington et al., “Observation of magnetic field generation via the weibel instability in interpenetrating plasma flows,” Nat. Phys. 11, 173–176 (2015)]. These results imply that electromagnetic instabilities are significant in the interaction of astrophysical conditions.

Mechanic- and hydraulic shock-absorbers - layout, construction, operation experience

International Nuclear Information System (INIS)

Kluge, M.

1981-01-01

The problem lies in the protection of the flexible supported power plant components against undesired sudden movements. Various shock absorbing systems are at disposal in this case: Mechanical and hydraulic shock absorbers, whose functioning systems are shown in figures. The operation experience showed a series of deficiencies, as demonstrated on various figures. In order to avoid them, some important recommendations are given. Requirements and layout are demonstrated according to todays' state-of-the-art. The admissible stresses, resulting from the summary of various specifications for the analytical evidence will be described. Development and construction will be explained in detail by means of pictures with cross sections of original shock absorbers. Todays' construction characteristics will be summarized. The final remark includes a request for generally valid guidelines. (orig.) [de

Experimental Shock Transformation of Gypsum to Anhydrite: A New Low Pressure Regime Shock Indicator

Science.gov (United States)

Bell, Mary S.; Zolensky, Michael E.

2011-01-01

The shock behavior of gypsum is important in understanding the Cretaceous/Paleogene event and other terrestrial impacts that contain evaporite sediments in their targets (e.g., Mars Exploration Rover Spirit detected sulfate at Gusev crater, [1]). Most interest focuses on issues of devolatilization to quantify the production of SO2 to better understand its role in generating a temporary atmosphere and its effects on climate and biota [2,3]. Kondo and Ahrens [4] measured induced radiation emitted from single crystal gypsum shocked to 30 and 40 GPa. They observed greybody emission spectra corresponding to temperatures in the range of 3,000 to 4,000 K that are a factor of 2 to 10 times greater than calculated pressure-density energy equation of state temperatures (Hugoniot) and are high enough to melt gypsum. Chen et al. [5] reported results of shock experiments on anhydrite, gypsum, and mixtures of these phases with silica. Their observations indicated little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another report of shock experiments on calcite, anhydrite, and gypsum, Badjukov et al. [6] observed only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa but have not experimentally shocked gypsum in a step-wise manner to constrain possible incipient transformation effects. Schmitt and Hornemann [7] shock loaded anhydrite and quartz to a peak pressure of 60 GPa and report the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggested that recrystallization of anhydrite grains is the result of a solid-state transformation. They concluded that significant decomposition of anhydrite requires shock pressures higher than 60 GPa. Gupta et al. [8

Spall wave-profile and shock-recovery experiments on depleted uranium

International Nuclear Information System (INIS)

Hixson, R.S.; Vorthman, J.E.; Gustavsen, R.L.; Zurek, A.K.; Thissell, W.R.; Tonks, D.L.

1998-01-01

Depleted Uranium of two different purity levels has been studied to determine spall strength under shock wave loading. A high purity material with approximately 30 ppm of carbon impurities was shock compressed to two different stress levels, 37 and 53 kbar. The second material studied was uranium with about 300 ppm of carbon impurities. This material was shock loaded to three different final stress level, 37, 53, and 81 kbar. Two experimental techniques were used in this work. First, time-resolved free surface particle velocity measurements were done using a VISAR velocity interferometer. The second experimental technique used was soft recovery of samples after shock loading. These two experimental techniques will be briefly described here and VISAR results will be shown. Results of the spall recovery experiments and subsequent metallurgical analyses are described in another paper in these proceedings. copyright 1998 American Institute of Physics

Optimal Design of Shock Tube Experiments for Parameter Inference

KAUST Repository

Bisetti, Fabrizio; Knio, Omar

2014-01-01

We develop a Bayesian framework for the optimal experimental design of the shock tube experiments which are being carried out at the KAUST Clean Combustion Research Center. The unknown parameters are the pre-exponential parameters and the activation

Crack propagation behavior of TiN coatings by laser thermal shock experiments

International Nuclear Information System (INIS)

Choi, Youngkue; Jeon, Seol; Jeon, Min-seok; Shin, Hyun-Gyoo; Chun, Ho Hwan; Lee, Youn-seoung; Lee, Heesoo

2012-01-01

Highlights: ► The crack propagation behavior of TiN coating after laser thermal shock experiment was observed by using FIB and TEM. ► Intercolumnar cracks between TiN columnar grains were predominant cracking mode after laser thermal shock. ► Cracks were propagated from the coating surface to the substrate at low laser pulse energy and cracks were originated at coating-substrate interface at high laser pulse energy. ► The cracks from the interface spread out transversely through the weak region of the columnar grains by repetitive laser shock. - Abstract: The crack propagation behavior of TiN coatings, deposited onto 304 stainless steel substrates by arc ion plating technique, related to a laser thermal shock experiment has been investigated using focused ion beam (FIB) and transmission electron microscopy (TEM). The ablated regions of TiN coatings by laser ablation system have been investigated under various conditions of pulse energies and number of laser pulses. The intercolumnar cracks were predominant cracking mode following laser thermal shock tests and the cracks initiated at coating surface and propagated in a direction perpendicular to the substrate under low loads conditions. Over and above those cracks, the cracks originated from coating-substrate interface began to appear with increasing laser pulse energy. The cracks from the interface also spread out transversely through the weak region of the columnar grains by repetitive laser shock.

Planar radiative shock experiments and their comparison to simulations

International Nuclear Information System (INIS)

Reighard, A. B.; Drake, R. P.; Mucino, J. E.; Knauer, J. P.; Busquet, M.

2007-01-01

Recent experiments have obtained radiographic data from shock waves driven at >100 km/s in xenon gas, and Thomson scattering data from similar experiments using argon gas. Presented here is a review of these experiments, followed by an outline of the discrepancies between the data and the results of one-dimensional simulations. Simulations using procedures that work well for similar but nonradiative experiments show inconsistencies between the measured position of the interface of the beryllium and xenon and the calculated position for these experiments. Sources of the discrepancy are explored

Laser driven shock wave experiments for equation of state studies at megabar pressures

CERN Document Server

Pant, H C; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

2002-01-01

We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 mu m wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments.

Laser driven shock wave experiments for equation of state studies at megabar pressures

International Nuclear Information System (INIS)

Pant, H C; Shukla, M; Senecha, V K; Bandyopadhyay, S; Rai, V N; Khare, P; Bhat, R K; Gupta, N K; Godwal, B K

2002-01-01

We present the results from laser driven shock wave experiments for equation of state (EOS) studies of gold metal. An Nd:YAG laser chain (2 J, 1.06 μm wavelength, 200 ps pulse FWHM) is used to generate shocks in planar Al foils and Al + Au layered targets. The EOS of gold in the pressure range of 9-13 Mbar is obtained using the impedance matching technique. The numerical simulations performed using the one-dimensional radiation hydrodynamic code support the experimental results. The present experimental data show remarkable agreement with the existing standard EOS models and with other experimental data obtained independently using laser driven shock wave experiments

Shock compression experiments on Lithium Deuteride single crystals.

Energy Technology Data Exchange (ETDEWEB)

Knudson, Marcus D.; Desjarlais, Michael Paul; Lemke, Raymond W.

2014-10-01

S hock compression exper iments in the few hundred GPa (multi - Mabr) regime were performed on Lithium Deuteride (LiD) single crystals . This study utilized the high velocity flyer plate capability of the Sandia Z Machine to perform impact experiments at flyer plate velocities in the range of 17 - 32 km/s. Measurements included pressure, density, and temperature between %7E200 - 600 GPa along the Principal Hugoniot - the locus of end states achievable through compression by large amplitude shock waves - as well as pressure and density of re - shock states up to %7E900 GPa . The experimental measurements are compared with recent density functional theory calculations as well as a new tabular equation of state developed at Los Alamos National Labs.

Large-scale thermal-shock experiments with clad and unclad steel cylinders

International Nuclear Information System (INIS)

Cheverton, R.D.

1992-01-01

Flaw behavior trends associated with pressurized-thermal-shock (PTS) loading of pressurized-water-reactor pressure vessels have been under investigation at the Oak Ridge National Laboratory for nearly 20 years. During that time, twelve thermal-shock experiments with thick-walled (152 mm) steel cylinders were conducted as a part of the investigations. The first eight experiments were conducted with unclad cylinders initially containing shallow (8--19 mm) two-dimensional and semicircular inner-surface flaws. These experiments demonstrated, in good agreement with linear elastic fracture mechanics, crack initiation and arrest, a series of initiation/arrest events with deep penetration of the wall, long crack jumps, arrest with the stress intensity factor (K I ) increasing with crack depth, extensive surface extension of an initially short and shallow (semicircular) flaw, and warm prestressing with K I ≤ 0. The remaining four experiments were conducted with clad cylinders containing initially shallow (19--24 mm) semielliptical subclad and surface flaws at the inner surface. In the first of these experiments one of six equally spaced (60 degrees) open-quotes identicalclose quotes subclad flaws extended nearly the length of the cylinder (1,220 mm) beneath the cladding (no crack extension into the cladding) and nearly 50% of the wall, radially. For the final experiment, four of the semielliptical subclad flaws that had not propagated previously were converted to surface flaws, and they experienced extensive extension beneath the cladding with no cracking of the cladding. Information from this series of thermal-shock experiments is being used in the evaluation of the PTS issue

Laser-generated shock-wave experiments in metals above 1 TPa

International Nuclear Information System (INIS)

Trainor, R.J.; Shaner, J.W.; Auerbach, J.M.; Phillion, D.W.

1978-01-01

Some initial experiments are described which form part of a new program aimed at significantly extending the range of high pressures and densities which may be explored in laboratory equation-of-state (EOS) experiments. These experiments will utilize high-energy lasers, such as those employed in the Laser Fusion Program at Lawrence Livermore Laboratory (LLL), to generate intense shock waves in materials of interest

Pressurized-thermal-shock experiments

International Nuclear Information System (INIS)

Whitman, G.D.; McCulloch, R.W.

1982-01-01

The primary objective of the ORNL pressurized-thermal-shock (PTS) experiments is to verify analytical methods that are used to predict the behavior of pressurized-water-reactor vessels under these accident conditions involving combined pressure and thermal loading. The criteria on which the experiments are based are: scale large enough to attain effective flaw border triaxial restraint and a temperature range sufficiently broad to produce a progression from frangible to ductile behavior through the wall at a given time; use of materials that can be completely characterized for analysis; stress states comparable to the actual vessel in zones of potential flaw extension; range of behavior to include cleavage initiation and arrest, cleavage initiation and arrest on the upper shelf, arrest in a high K/sub I/ gradient, warm prestressing, and entirely ductile behavior; long and short flaws with and without stainless steel cladding; and control of loads to prevent vessel burst, except as desired. A PTS test facility is under construction which will enable the establishment and control of wall temperature, cooling rate, and pressure on an intermediate test vessel (ITV) in order to simulate stress states representative of an actual reactor pressure vessel

Assessment of In Situ Time Resolved Shock Experiments at Synchrotron Light Sources*

Science.gov (United States)

Belak, J.; Ilavsky, J.; Hessler, J. P.

2005-07-01

Prior to fielding in situ time resolved experiments of shock wave loading at the Advanced Photon Source, we have performed feasibility experiments assessing a single photon bunch. Using single and poly-crystal Al, Ti, V and Cu shock to incipient spallation on the gas gun, samples were prepared from slices normal to the spall plane of thickness 100-500 microns. In addition, single crystal Al of thickness 500 microns was shocked to incipient spallation and soft recovered using the LLNL e-gun mini-flyer system. The e-gun mini-flyer impacts the sample target producing a 10's ns flat-top shock transient. Here, we present results for imaging, small-angle scattering (SAS), and diffraction. In particular, there is little SAS away from the spall plane and significant SAS at the spall plane, demonstrating the presence of sub-micron voids. * Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. W-31-109-Eng-38 and work performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

Numerical simulations of a nonequilibrium argon plasma in a shock-tube experiment

Science.gov (United States)

Cambier, Jean-Luc

1991-01-01

A code developed for the numerical modeling of nonequilibrium radiative plasmas is applied to the simulation of the propagation of strong ionizing shock waves in argon gas. The simulations attempt to reproduce a series of shock-tube experiments which will be used to validate the numerical models and procedures. The ability to perform unsteady simulations makes it possible to observe some fluctuations in the shock propagation, coupled to the kinetic processes. A coupling mechanism by pressure waves, reminiscent of oscillation mechanisms observed in detonation waves, is described. The effect of upper atomic levels is also briefly discussed.

Managing reality shock: Expectations versus experiences of graduate engineers

Directory of Open Access Journals (Sweden)

Sarah Riordan

2007-10-01

Full Text Available The objective of the study is an analysis of the relationship between the work expectations and experiences of graduate engineers during their early career period. It reports on discrepancies in graduates’ expectations of the world of work and the reality of the early career stage. Conclusions include recommendations of how "reality shock" can be managed better by both organisations and individuals. Qualitative data were obtained through in-depth interviews with sixteen participants with less than five years work experience, employed in a large utility organisation in the Western Cape. Results indicate that participants experience significant incongruence between their expectations of work and work experiences.

Excitation of intense shock waves by soft X-radiation

Energy Technology Data Exchange (ETDEWEB)

Branitskij, A V; Fortov, V E; Danilenko, K N; Dyabilin, K S; Grabovskij, E V; Vorobev, O Yu; Lebedev, M E; Smirnov, V P; Zakharov, A E; Persyantsev, I V [Troitsk Inst. of Innovative and Fusion Research, Troitsk (Russian Federation)

1997-12-31

Investigation of the shock waves generated by soft x radiation in Al, Sn, Fe, and Pb targets is reported. The soft x radiation was induced by the dynamic compression and heating of the cylindrical z-pinch plasma generated in the ANGARA-5-1 pulsed power machine. The temperature of the z-pinch plasma was as high as 60 - 120 eV, and the duration of the x-ray pulse reached 30 ns FWHM. Thick stepped Al/Pb, Sn/Pb, and pure Pb targets were used. The results of experiments show that uniform intense shock waves can be generated by z-pinch plasma soft x-ray radiation. The uniformity of the shock is very high. At a flux power of the order of several TW/cm{sup 2}, a shock pressure of some hundreds of GPa was achieved. (J.U.). 3 figs., 11 refs.

Excitation of intense shock waves by soft X-radiation

International Nuclear Information System (INIS)

Branitskij, A.V.; Fortov, V.E.; Danilenko, K.N.; Dyabilin, K.S.; Grabovskij, E.V.; Vorobev, O. Yu.; Lebedev, M.E.; Smirnov, V.P.; Zakharov, A.E.; Persyantsev, I.V.

1996-01-01

Investigation of the shock waves generated by soft x radiation in Al, Sn, Fe, and Pb targets is reported. The soft x radiation was induced by the dynamic compression and heating of the cylindrical z-pinch plasma generated in the ANGARA-5-1 pulsed power machine. The temperature of the z-pinch plasma was as high as 60 - 120 eV, and the duration of the x-ray pulse reached 30 ns FWHM. Thick stepped Al/Pb, Sn/Pb, and pure Pb targets were used. The results of experiments show that uniform intense shock waves can be generated by z-pinch plasma soft x-ray radiation. The uniformity of the shock is very high. At a flux power of the order of several TW/cm 2 , a shock pressure of some hundreds of GPa was achieved. (J.U.). 3 figs., 11 refs

Economic Shocks and Subjective Well-Being: Evidence from a Quasi-Experiment

DEFF Research Database (Denmark)

Hariri, Jacob Gerner; Bjørnskov, Christian; Justesen, Mogens Kamp

2016-01-01

This paper examines how economic shocks affect individual well-being in developing countries. Using the case of a sudden and unanticipated currency devaluation in Botswana as a quasi-experiment, we examine how this monetary shock affects individuals’ evaluations of well-being. We do so by using...... micro-level survey data, which – incidentally – was collected in the days surrounding the devaluation. The chance occurrence of the devaluation during the time of the survey enables us to use pre-treatment respondents, surveyed before the devaluation, as approximate counterfactuals for post......-treatment respondents, surveyed after the devaluation. Our estimates show that the devaluation had a large and significantly negative effect on individuals’ evaluations of subjective well-being. These results suggest that macroeconomic shocks, such as unanticipated currency devaluations, may have significant short...

Overview and recent results of the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Weber, T. E.; Smith, R. J.; Hsu, S. C.; Omelchenko, Y.

2015-11-01

Recent machine and diagnostics upgrades to the Magnetized Shock Experiment (MSX) at LANL have enabled unprecedented access to the physical processes arising from stagnating magnetized (β ~ 1), collisionless, highly supersonic (M ,MA ~ 10) flows, similar in dimensionless parameters to those found in both space and astrophysical shocks. Hot (100s of eV during translation), dense (1022 - 1023 m-3) Field Reversed Configuration (FRC) plasmoids are accelerated to high velocities (100s of km/s) and subsequently impact against a static target such as a strong parallel or anti-parallel (reconnection-wise) magnetic mirror, a solid obstacle, or neutral gas cloud to recreate the physics of interest with characteristic length and time scales that are both large enough to observe yet small enough to fit within the experiment. Long-lived (>50 μs) stagnated plasmas with density enhancement much greater than predicted by fluid theory (>4x) are observed, accompanied by discontinuous plasma structures indicating shocks and jetting (visible emission and interferometry) and copious >1 keV x-ray emission. An overview of the experimental program will be presented, including machine design and capabilities, diagnostics, and an examination of the physical processes that occur during stagnation against a variety of targets. Supported by the DOE Office of Fusion Energy Sciences under contract DE-AC52-06NA25369.

Optimal Design and Model Validation for Combustion Experiments in a Shock Tube

KAUST Repository

Long, Quan

2014-01-06

We develop a Bayesian framework for the optimal experimental design of the shock tube experiments which are being carried out at the KAUST Clean Combustion Center. The unknown parameters are the pre-exponential parameters and the activation energies in the reaction rate functions. The control parameters are the initial hydrogen concentration and the temperature. First, we build a polynomial based surrogate model for the observable related to the reactions in the shock tube. Second, we use a novel MAP based approach to estimate the expected information gain in the proposed experiments and select the best experimental set-ups corresponding to the optimal expected information gains. Third, we use the synthetic data to carry out virtual validation of our methodology.

Shock loading predictions from application of indicial theory to shock-turbulence interactions

Science.gov (United States)

Keefe, Laurence R.; Nixon, David

1991-01-01

A sequence of steps that permits prediction of some of the characteristics of the pressure field beneath a fluctuating shock wave from knowledge of the oncoming turbulent boundary layer is presented. The theory first predicts the power spectrum and pdf of the position and velocity of the shock wave, which are then used to obtain the shock frequency distribution, and the pdf of the pressure field, as a function of position within the interaction region. To test the validity of the crucial assumption of linearity, the indicial response of a normal shock is calculated from numerical simulation. This indicial response, after being fit by a simple relaxation model, is used to predict the shock position and velocity spectra, along with the shock passage frequency distribution. The low frequency portion of the shock spectra, where most of the energy is concentrated, is satisfactorily predicted by this method.

An assessment of the 3D geometric surrogacy of shock timing diagnostic techniques for tuning experiments on the NIF

Science.gov (United States)

Robey, H. F.; Munro, D. H.; Spears, B. K.; Marinak, M. M.; Jones, O. S.; Patel, M. V.; Haan, S. W.; Salmonson, J. D.; Landen, O. L.; Boehly, T. R.; Nikroo, A.

2008-05-01

Ignition capsule implosions planned for the National Ignition Facility (NIF) require a pulse shape with a carefully designed series of four steps, which launch a corresponding series of shocks through the ablator and DT ice shell. The relative timing of these shocks is critical for maintaining the DT fuel on a low adiabat. The current NIF specification requires that the timing of all four shocks be tuned to an accuracy of surrogacy of this modified geometry, 3D simulations using HYDRA [1] have been performed. The results from simulations of a quarter of the target geometry are presented. Comparisons of the hohlraum drive conditions and the resulting effect on the shock timing in the keyhole hohlraum are compared with the corresponding results for the standard ignition hohlraum.

A Fiber Interferometer for the Magnetized Shock Experiment

International Nuclear Information System (INIS)

Yoo, Christian

2012-01-01

The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory requires remote diagnostics of plasma density. Laser interferometry can be used to determine the line-integrated density of the plasma. A multi-chord heterodyne fiber optic Mach-Zehnder interferometer is being assembled and integrated into the experiment. The advantage of the fiber coupling is that many different view chords can be easily obtained by simply moving transmit and receive fiber couplers. Several such fiber sets will be implemented to provide a time history of line-averaged density for several chords at once. The multiple chord data can then be Abel inverted to provide radially resolved spatial profiles of density. We describe the design and execution of this multiple fiber interferometer.

The Septic Shock 3.0 Definition and Trials: A Vasopressin and Septic Shock Trial Experience.

Science.gov (United States)

Russell, James A; Lee, Terry; Singer, Joel; Boyd, John H; Walley, Keith R

2017-06-01

The Septic Shock 3.0 definition could alter treatment comparisons in randomized controlled trials in septic shock. Our first hypothesis was that the vasopressin versus norepinephrine comparison and 28-day mortality of patients with Septic Shock 3.0 definition (lactate > 2 mmol/L) differ from vasopressin versus norepinephrine and mortality in Vasopressin and Septic Shock Trial. Our second hypothesis was that there are differences in plasma cytokine levels in Vasopressin and Septic Shock Trial for lactate less than or equal to 2 versus greater than 2 mmol/L. Retrospective analysis of randomized controlled trial. Multicenter ICUs. We compared vasopressin-to-norepinephrine group 28- and 90-day mortality in Vasopressin and Septic Shock Trial in lactate subgroups. We measured 39 cytokines to compare patients with lactate less than or equal to 2 versus greater than 2 mmol/L. Patients with septic shock with lactate greater than 2 mmol/L or less than or equal to 2 mmol/L, randomized to vasopressin or norepinephrine. Concealed vasopressin (0.03 U/min.) or norepinephrine infusions. The Septic Shock 3.0 definition would have decreased sample size by about half. The 28- and 90-day mortality rates were 10-12 % higher than the original Vasopressin and Septic Shock Trial mortality. There was a significantly (p = 0.028) lower mortality with vasopressin versus norepinephrine in lactate less than or equal to 2 mmol/L but no difference between treatment groups in lactate greater than 2 mmol/L. Nearly all cytokine levels were significantly higher in patients with lactate greater than 2 versus less than or equal to 2 mmol/L. The Septic Shock 3.0 definition decreased sample size by half and increased 28-day mortality rates by about 10%. Vasopressin lowered mortality versus norepinephrine if lactate was less than or equal to 2 mmol/L. Patients had higher plasma cytokines in lactate greater than 2 versus less than or equal to 2 mmol/L, a brisker cytokine response to infection. The Septic

The Shock/Shear platform for planar radiation-hydrodynamics experiments on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Doss, F. W., E-mail: fdoss@lanl.gov; Kline, J. L.; Flippo, K. A.; Perry, T. S.; DeVolder, B. G.; Tregillis, I.; Loomis, E. N.; Merritt, E. C.; Murphy, T. J.; Welser-Sherrill, L.; Fincke, J. R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2015-05-15

An indirectly-driven shock tube experiment fielded on the National Ignition Facility (NIF) was used to create a high-energy-density hydrodynamics platform at unprecedented scale. Scaling up a shear-induced mixing experiment previously fielded at OMEGA, the NIF shear platform drives 130 μm/ns shocks into a CH foam-filled shock tube (∼ 60 mg/cc) with interior dimensions of 1.5 mm diameter and 5 mm length. The pulse-shaping capabilities of the NIF are used to extend the drive for >10 ns, and the large interior tube volumes are used to isolate physics-altering edge effects from the region of interest. The scaling of the experiment to the NIF allows for considerable improvement in maximum driving time of hydrodynamics, in fidelity of physics under examination, and in diagnostic clarity. Details of the experimental platform and post-shot simulations used in the analysis of the platform-qualifying data are presented. Hydrodynamic scaling is used to compare shear data from OMEGA with that from NIF, suggesting a possible change in the dimensionality of the instability at late times from one platform to the other.

Microgravity Experiment: The Fate of Confined Shock Waves

Science.gov (United States)

Kobel, P.; Obreschkow, D.; Dorsaz, N.; de Bosset, A.; Farhat, M.

2007-11-01

Shockwave induced cavitation is a form of hydrodynamic cavitation generated by the interaction of shock waves with vapor nuclei and microscopic impurities. Both the shock waves and the induced cavitation are known as sources of erosion damage in hydraulic industrial systems and hence represent an important research topic in fluid dynamics. Here we present the first investigation of shock wave induced cavitation inside closed and isolated liquid volumes, which confine the shock wave by reflections and thereby promise a particularly strong coupling with cavitation. A microgravity platform (ESA, 42^nd parabolic flight campaign) was used to produce stable water drops with centimetric diameters. Inside these drops, a fast electrical discharge was generated to release a strong shock wave. This setting results in an amplified form of shockwave induced cavitation, visible in high-speed images as a transient haze of sub-millimetric bubbles synchronized with the shockwave radiation. A comparison between high-speed visualizations and 3D simulations of a shock front inside a liquid sphere reveals that focus zones within the drop lead to a significantly increased density of induced cavitation. Considering shock wave crossing and focusing may hence prove crucially useful to understand the important process of cavitation erosion.

Effects of response-shock interval and shock intensity on free-operant avoidance responding in the pigeon1

Science.gov (United States)

Klein, Marty; Rilling, Mark

1972-01-01

Two experiments investigated free-operant avoidance responding with pigeons using a treadle-pressing response. In Experiment I, pigeons were initially trained on a free-operant avoidance schedule with a response-shock interval of 32 sec and a shock-shock interval of 10 sec, and were subsequently exposed to 10 values of the response-shock parameter ranging from 2.5 to 150 sec. The functions relating response rate to response-shock interval were similar to the ones reported by Sidman in his 1953 studies employing rats, and were independent of the order of presentation of the response-shock values. Shock rates decreased as response-shock duration increased. In Experiment II, a free-operant avoidance schedule with a response-shock interval of 20 sec and a shock-shock interval of 5 sec was used, and shock intensities were varied over five values ranging from 2 to 32 mA. Response rates increased markedly as shock intensity increased from 2 to 8 mA, but rates changed little with further increases in shock intensity. Shock rates decreased as intensity increased from 2 to 8 mA, and showed little change as intensity increased from 8 to 32 mA. PMID:4652617

Attenuation of surface waves in porous media: Shock wave experiments and modelling

NARCIS (Netherlands)

Chao, G.E; Smeulders, D.M.J.; Dongen, van M.E.H.

2005-01-01

In this project we conduct experimental and numerical investigations on the attenuation mechanisms of surface waves in poroelastic materials. Viscous dissipation effects are modelled in the framework of Biot's theory. The experiments are performed using a shock tube technique. Quantitative agreement

Space Shuttle Program (SSP) Shock Test and Specification Experience for Reusable Flight Hardware Equipment

Science.gov (United States)

Larsen, Curtis E.

2012-01-01

As commercial companies are nearing a preliminary design review level of design maturity, several companies are identifying the process for qualifying their multi-use electrical and mechanical components for various shock environments, including pyrotechnic, mortar firing, and water impact. The experience in quantifying the environments consists primarily of recommendations from Military Standard-1540, Product Verification Requirement for Launch, Upper Stage, and Space Vehicles. Therefore, the NASA Engineering and Safety Center (NESC) formed a team of NASA shock experts to share the NASA experience with qualifying hardware for the Space Shuttle Program (SSP) and other applicable programs and projects. Several team teleconferences were held to discuss past experience and to share ideas of possible methods for qualifying components for multiple missions. This document contains the information compiled from the discussions

Shock-induced chemistry in organic materials

Energy Technology Data Exchange (ETDEWEB)

Dattelbaum, Dana M [Los Alamos National Laboratory; Sheffield, Steve [Los Alamos National Laboratory; Engelke, Ray [Los Alamos National Laboratory; Manner, Virginia [Los Alamos National Laboratory; Chellappa, Raja [Los Alamos National Laboratory; Yoo, Choong - Shik [WASHINGTON STATE UNIV

2011-01-20

The combined 'extreme' environments of high pressure, temperature, and strain rates, encountered under shock loading, offer enormous potential for the discovery of new paradigms in chemical reactivity not possible under more benign conditions. All organic materials are expected to react under these conditions, yet we currently understand very little about the first bond-breaking steps behind the shock front, such as in the shock initiation of explosives, or shock-induced reactivity of other relevant materials. Here, I will present recent experimental results of shock-induced chemistry in a variety of organic materials under sustained shock conditions. A comparison between the reactivity of different structures is given, and a perspective on the kinetics of reaction completion under shock drives.

Phase transition in cadmium sulfide single crystals shocked along the c axis

International Nuclear Information System (INIS)

Tang, Z.P.; Gupta, Y.M.

1997-01-01

Cadmium sulfide crystals were shocked along the crystal c axis to peak stresses ranging between 18 and 75 kbar. Stress-time profiles were measured both at the impact surface and after transmission through 1 to 2-mm-thick samples. Detailed analysis of the present data in combination with published static results makes a persuasive case for the completion of the wurtzite to rocksalt phase change in less than 0.2 μs under shock loading. The main findings are: the transition stress is measured to be 32.5±1kbar; transformation to the final state is a two step process with the first step being too rapid (less than 10 ns) to be observed in our experiments and the second step occurring in 0.1 to 0.2 μs; the transition occurs directly from the elastic state prior to any plastic deformation. The calculated mean stress for the transition is 22.9 kbar in good agreement with the 23 kbar pressure reported in static high pressure studies; the presence of large shear stress has no effect on the transition pressure. Our results suggest that the onset of the phase transition results in plastic deformation and, subsequently, the phase transition and plasticity are coupled under shock loading. copyright 1997 American Institute of Physics

Strain measurements during pressurized thermal shock experiment

International Nuclear Information System (INIS)

Tarso Vida Gomes, P. de; Julio Ricardo Barreto Cruz; Tanius Rodrigues Mansur; Denis Henrique Bianchi Scaldaferri; Miguel Mattar Neto

2005-01-01

For the life extension of nuclear power plants, the residual life of most of their components must be evaluated along all their operating time. Concerning the reactor pressure vessel, the pressurized thermal shock (PTS) is a very important event to be considered. For better understanding the effects of this kind of event, tests are made. The approach described here consisted of building a simplified in-scale physical model of the reactor pressure vessel, submitting it to the actual operating temperature and pressure conditions and provoking a thermal shock by means of cold water flow in its external surface. To conduct such test, the Nuclear Technology Development Center (CDTN) has been conducting several studies related to PTS and has also built a laboratory that has made possible the simulation of the PTS loading conditions. Several cracks were produced in the external surface of the reactor pressure vessel model. Strain gages were fixed by means of electrical discharge welding over the cracks regions in both external and internal surfaces. The temperature was monitored in 10 points across the vessel wall. The internal pressure was manually controlled and monitored using a pressure transducer. Two PTS experiments were conducted and this paper presents the strain measurement procedures applied to the reactor pressure vessel model, during the PTS, using strain gages experimental methodology. (authors)

Sound velocity of tantalum under shock compression in the 18–142 GPa range

Energy Technology Data Exchange (ETDEWEB)

Xi, Feng, E-mail: xifeng@caep.cn; Jin, Ke; Cai, Lingcang, E-mail: cai-lingcang@aliyun.com; Geng, Huayun; Tan, Ye; Li, Jun [National Key Laboratory of Shock Waves and Detonation Physics, Institute of Fluid Physics, CAEP, P.O. Box 919-102 Mianyang, Sichuan 621999 (China)

2015-05-14

Dynamic compression experiments of tantalum (Ta) within a shock pressure range from 18–142 GPa were conducted driven by explosive, a two-stage light gas gun, and a powder gun, respectively. The time-resolved Ta/LiF (lithium fluoride) interface velocity profiles were recorded with a displacement interferometer system for any reflector. Sound velocities of Ta were obtained from the peak state time duration measurements with the step-sample technique and the direct-reverse impact technique. The uncertainty of measured sound velocities were analyzed carefully, which suggests that the symmetrical impact method with step-samples is more accurate for sound velocity measurement, and the most important parameter in this type experiment is the accurate sample/window particle velocity profile, especially the accurate peak state time duration. From these carefully analyzed sound velocity data, no evidence of a phase transition was found up to the shock melting pressure of Ta.

Shock Dynamics in Stellar Outbursts. I. Shock Formation

Energy Technology Data Exchange (ETDEWEB)

Ro, Stephen; Matzner, Christopher D., E-mail: ro@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

2017-05-20

Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

Pressurized-thermal-shock experiments: PTSE-1 results and PTSE-2 plans

International Nuclear Information System (INIS)

Bryan, R.H.; Nanstad, R.K.; Wanner, R.; Merkle, J.G.; Robinson, G.C.; Whitman, G.D.

1985-01-01

The first pressurized-thermal-shock experiment (PTSE-1) was performed with a vessel with a 1-m-long flaw in a plug of specially tempered steel having the composition of SA-508 forging steel. The second experiment (PTSE-2) will have a similar arrangement, but the material in which the flaw will be implanted is being prepared to have low tearing resistance. Special tempering of a 2 1/4 Cr - 1 Mo steel plate has been shown to induce a low Charpy impact energy in the upper-shelf temperature range. The purpose of PTSE-2 is to investigate the fracture behavior of low-upper-shelf material in a vessel under the combined loading of concurrent pressure and thermal shock. The primary objective of the experimental plan is to induce a rapidly propagating cleavage fracture under conditions that are likely to induce a ductile tearing instability at the time of arrest of the cleavage fracture. The secondary objective of the test is to extend the range of the investigation of warm prestressing. 11 figs

Discrimination of Thermal versus Mechanical Effects of Shock on Rock Magnetic Properties of Spherically Shocked up to 10-160 GPa Basalt and Diabase

Science.gov (United States)

Bezaeva, N. S.; Swanson-Hysell, N.; Tikoo, S.; Badyukov, D. D.; Kars, M. A. C.; Egli, R.; Chareev, D. A.; Fairchild, L. M.

2016-12-01

Understanding how shock waves generated during hypervelocity impacts affect rock magnetic properties is key for interpreting the paleomagnetic records of lunar rocks, meteorites, and cratered planetary surfaces. Laboratory simulations of impacts show that ultra-high shocks may induce substantial post-shock heating of the target material. At high pressures (>10 GPa), shock heating occurs in tandem with mechanical effects, such as grain fracturing and creation of crystallographic defects and dislocations within magnetic grains. This makes it difficult to conclude whether shock-induced changes in the rock magnetic properties of target materials are primarily associated with mechanical or thermal effects. Here we present novel experimental methods to discriminate between mechanical and thermal effects of shock on magnetic properties and illustrate it with two examples of spherically shocked terrestrial basalt and diabase [1], which were shocked to pressures of 10 to >160 GPa, and investigate possible explanations for the observed shock-induced magnetic hardening (i.e., increase in remanent coercivity Bcr). The methods consist of i) conducting extra heating experiments at temperatures resembling those experienced during high-pressure shock events on untreated equivalents of shocked rocks (with further comparison of Bcr of shocked and heated samples) and ii) quantitative comparison of high-resolution first-order reversal curve (FORC) diagrams (field step: 0.5-0.7 mT) for shocked, heated and untreated specimens. Using this approach, we demonstrated that the shock-induced coercivity hardening in our samples is predominantly due to solid-state, mechanical effects of shock rather than alteration associated with shock heating. Indeed, heating-induced changes in Bcr in the post-shock temperature range were minor. Visual inspection of FORC contours (in addition to detailed analyses) reveals a stretching of the FORC distribution of shocked sample towards higher coercivities

Spherical strong-shock generation for shock-ignition inertial fusion

Energy Technology Data Exchange (ETDEWEB)

Theobald, W.; Seka, W.; Lafon, M.; Anderson, K. S.; Hohenberger, M.; Marshall, F. J.; Michel, D. T.; Solodov, A. A.; Stoeckl, C.; Edgell, D. H.; Yaakobi, B.; Shvydky, A. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Nora, R.; Betti, R. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Department of Mechanical Engineering and Department of Physics, University of Rochester, Rochester, New York 14623 (United States); Casner, A.; Reverdin, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Ribeyre, X.; Vallet, A. [Université de Bordeaux-CNRS-CEA, CELIA (Centre Lasers Intenses et Applications) UMR 5107 F-33400 Talence (France); Peebles, J.; Beg, F. N. [University of California, San Diego, La Jolla, California 92093 (United States); and others

2015-05-15

Recent experiments on the Laboratory for Laser Energetics' OMEGA laser have been carried out to produce strong shocks in solid spherical targets with direct laser illumination. The shocks are launched at pressures of several hundred Mbars and reach Gbar upon convergence. The results are relevant to the validation of the shock-ignition scheme and to the development of an OMEGA experimental platform to study material properties at Gbar pressures. The experiments investigate the strength of the ablation pressure and the hot-electron production at incident laser intensities of ∼2 to 6 × 10{sup 15 }W/cm{sup 2} and demonstrate ablation pressures exceeding 300 Mbar, which is crucial to developing a shock-ignition target design for the National Ignition Facility. The timing of the x-ray flash from shock convergence in the center of the solid plastic target is used to infer the ablation and shock pressures. Laser–plasma instabilities produce hot-electrons with a moderate temperature (<100 keV). The instantaneous conversion efficiencies of laser power into hot-electron power reached up to ∼15% in the intensity spike. The large amount of hot electrons is correlated with an earlier x-ray flash and a strong increase in its magnitude. This suggests that hot electrons contribute to the augmentation of the shock strength.

A hierarchical method for Bayesian inference of rate parameters from shock tube data: Application to the study of the reaction of hydroxyl with 2-methylfuran

KAUST Repository

Kim, Daesang

2017-06-22

We developed a novel two-step hierarchical method for the Bayesian inference of the rate parameters of a target reaction from time-resolved concentration measurements in shock tubes. The method was applied to the calibration of the parameters of the reaction of hydroxyl with 2-methylfuran, which is studied experimentally via absorption measurements of the OH radical\\'s concentration following shock-heating. In the first step of the approach, each shock tube experiment is treated independently to infer the posterior distribution of the rate constant and error hyper-parameter that best explains the OH signal. In the second step, these posterior distributions are sampled to calibrate the parameters appearing in the Arrhenius reaction model for the rate constant. Furthermore, the second step is modified and repeated in order to explore alternative rate constant models and to assess the effect of uncertainties in the reflected shock\\'s temperature. Comparisons of the estimates obtained via the proposed methodology against the common least squares approach are presented. The relative merits of the novel Bayesian framework are highlighted, especially with respect to the opportunity to utilize the posterior distributions of the parameters in future uncertainty quantification studies.

Thin Foil Acceleration Method for Measuring the Unloading Isentropes of Shock-Compressed Matter

International Nuclear Information System (INIS)

Asay, J.R.; Chhabildas, L.C.; Fortov, V.E.; Kanel, G.I.; Khishchenko, K.V.; Lomonosov, I.V.; Mehlhorn, T.; Razorenov, S.V.; Utkin, A.V.

1999-01-01

This work has been performed as part of the search for possible ways to utilize the capabilities of laser and particle beams techniques in shock wave and equation of state physics. The peculiarity of these techniques is that we have to deal with micron-thick targets and not well reproducible incident shock wave parameters, so all measurements should be of a high resolution and be done in one shot. Besides the Hugoniots, the experimental basis for creating the equations of state includes isentropes corresponding to unloading of shock-compressed matter. Experimental isentrope data are most important in the region of vaporization. With guns or explosive facilities, the unloading isentrope is recovered from a series of experiments where the shock wave parameters in plates of standard low-impedance materials placed behind the sample are measured [1,2]. The specific internal energy and specific volume are calculated from the measured p(u) release curve which corresponds to the Riemann integral. This way is not quite suitable for experiments with beam techniques where the incident shock waves are not well reproducible. The thick foil method [3] provides a few experimental points on the isentrope in one shot. When a higher shock impedance foil is placed on the surface of the material studied, the release phase occurs by steps, whose durations correspond to that for the shock wave to go back and forth in the foil. The velocity during the different steps, connected with the knowledge of the Hugoniot of the foil, allows us to determine a few points on the isentropic unloading curve. However, the method becomes insensitive when the low pressure range of vaporization is reached in the course of the unloading. The isentrope in this region can be measured by recording the smooth acceleration of a thin witness plate foil. With the mass of the foil known, measurements of the foil acceleration will give us the vapor pressure

Pressure vessel fracture studies pertaining to a PWR LOCA-ECC thermal shock: experiments TSE-1 and TSE-2

International Nuclear Information System (INIS)

Cheverton, R.D.

1976-09-01

The LOCA-ECC Thermal Shock Program was established to investigate the potential for flaw propagation in pressurized-water reactor (PWR) vessels during injection of emergency core coolant following a loss-of-coolant accident. Studies thus far have included fracture mechanics analyses of typical PWRs, the design and construction of a thermal shock test facility, determination of material properties for test specimens, and two thermal shock experiments with 0.53-m-OD (21-in.) by 0.15-m-wall (6-in.) cylindrical test specimens. The PWR calculations indicated that under some circumstances crack propagation could be expected and that experiments should be conducted for cracks that would have the potential for propagation at least halfway through the wall

Shock-ignition relevant experiments with planar targets on OMEGA

Energy Technology Data Exchange (ETDEWEB)

Hohenberger, M.; Hu, S. X.; Anderson, K. S.; Boehly, T. R.; Sangster, T. C.; Seka, W.; Stoeckl, C.; Yaakobi, B. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Theobald, W.; Lafon, M.; Nora, R. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Betti, R.; Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Departments of Mechanical Engineering and Physics, University of Rochester, Rochester, New York 14627 (United States); Casner, A. [CEA, DAM, DIF, Arpajon (France); Fratanduono, D. E. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Ribeyre, X.; Schurtz, G. [Centre Lasers Intenses et Applications, CELIA, Université Bordeaux 1-CEA-CNRS, Talence (France)

2014-02-15

We report on laser-driven, strong-shock generation and hot-electron production in planar targets in the presence of a pre-plasma at shock-ignition (SI) relevant laser and pre-plasma conditions. 2-D simulations reproduce the shock dynamics well, indicating ablator shocks of up to 75 Mbar have been generated. We observe hot-electron temperatures of ∼70 keV at intensities of 1.4 × 10{sup 15} W/cm{sup 2} with multiple overlapping beams driving the two-plasmon decay instability. When extrapolated to SI-relevant intensities of ∼10{sup 16} W/cm{sup 2}, the hot electron temperature will likely exceed 100 keV, suggesting that tightly focused beams without overlap are better suited for launching the ignitor shock.

Fracture-mechanics data deduced from thermal-shock and related experiments with LWR pressure-vessel material

International Nuclear Information System (INIS)

Cheverton, R.D.; Canonico, D.A.; Iskander, S.K.; Bolt, S.E.; Holz, P.P.; Nanstad, R.K.; Stelzman, W.J.

1982-01-01

Pressurized water reactors (PWRs) are susceptible to certain types of hypothetical accidents that can subject the reactor pressure vessel to severe thermal shock, that is, a rapid cooling of the inner surface of the vessel wall. The thermal-shock loading, coupled with the radiation-induced reduction in the material fracture toughness, introduces the possibility of propagation of preexistent flaws and what at one time were regarded as somewhat unique fracture-oriented conditions. Several postulated reactor accidents have been analyzed to discover flaw behavior trends; seven intermediate-scale thermal-shock experiments with steel cylinders have been conducted; and corresponding materials characterization studies have been performed. Flaw behavior trends and related fracture-mechanics data deduced from these studies are discussed

Double shock experiments and reactive flow modeling on LX-17 to understand the reacted equation of state

International Nuclear Information System (INIS)

Vandersall, Kevin S; Garcia, Frank; Fried, Laurence E; Tarver, Craig M

2014-01-01

Experimental data from measurements of the reacted state of an energetic material are desired to incorporate reacted states in modeling by computer codes. In a case such as LX-17 (92.5% TATB and 7.5% Kel-F by weight), where the time dependent kinetics of reaction is still not fully understood and the reacted state may evolve over time, this information becomes even more vital. Experiments were performed to measure the reacted state of LX-17 using a double shock method involving the use of two flyer materials (with known properties) mounted on the projectile that send an initial shock through the material close to or above the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. By measuring the parameters of the first and second shock waves, information on the reacted state can be obtained. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments.

Interferometric windows characterization up to 450 K for shock wave experiments: Hugoniot curves and refractive index

Directory of Open Access Journals (Sweden)

Godefroit J.-L.

2012-08-01

Full Text Available Conventional shock wave experiments need interferometric windows in order to determine the equation of state of a large variety of metals. Lithium fluoride (LiF and sapphire are extensively used for that purpose because their optical transparencies enable the optical diagnostics at interfaces under a given range of shock pressure. In order to simulate and analyse the experiments it is necessary to gather a correct knowledge of the optical and mechanical properties of these windows. Therefore, our window supplies are systematically characterized and an experimental campaign under shock loading is conducted. Our preliminary work on LiF windows at 532 nm is in good agreement with literature data at room temperature and the new characterization at 450 K enables a better interpretation of our preheated target experiments. It confirms the predominant effect of density on optical properties under pressure and temperature. The present work demonstrates that the initial density determination is a key point and that the uncertainties need to be improved. For that purpose, complementary experiments are conducted on LiF windows with simplified target designs and enriched diagnostics, coupling VISAR (532 nm and PdV (1550 nm diagnostics. Furthermore, a similar campaign is conducted on sapphire windows with symmetric impact configuration.

Exploratory laser-driven shock wave studies

International Nuclear Information System (INIS)

Solem, J.C.; Veeser, L.R.

1977-11-01

We show the results of a feasibility study for investigating shock structure and for measuring equation-of-state parameters using high-energy, short-pulse lasers. We discuss the temporal and spatial structure of the luminosity from laser-driven shock unloading in aluminum foils. We demonstrate that shock velocity can be measured by observing the time interval between shock emergence across two thicknesses and show data for shocks of 1.3 and 2.1 Mbar. The fact that we observe shock fronts cleanly breaking through steps as small as 3 μm indicates that the shock front thickness is very small in the few megabar region; this is the first experimental verification that these fronts are not more than a few micrometers thick. We present approximate measurements of free-surface velocity. Finally, we speculate on the use of these techniques to obtain detailed equation-of-state data

Shock wave interaction with turbulence: Pseudospectral simulations

International Nuclear Information System (INIS)

Buckingham, A.C.

1986-01-01

Shock waves amplify pre-existing turbulence. Shock tube and shock wave boundary layer interaction experiments provide qualitative confirmation. However, shock pressure, temperature, and rapid transit complicate direct measurement. Computational simulations supplement the experimental data base and help isolate the mechanisms responsible. Simulations and experiments, particularly under reflected shock wave conditions, significantly influence material mixing. In these pseudospectral Navier-Stokes simulations the shock wave is treated as either a moving (tracked or fitted) domain boundary. The simulations assist development of code mix models. Shock Mach number and pre-existing turbulence intensity initially emerge as key parameters. 20 refs., 8 figs

Melting Behaviour of Mo by Shock Wave Experiment

International Nuclear Information System (INIS)

Xiu-Lu, Zhang; Ling-Cang, Cai; Jun, Chen; Ji-An, Xu; Fu-Qian, Jing

2008-01-01

In order to clarify the apparent discrepancy in determinations of melting temperature T m of Mo between diamond-anvil cell (DAC) measurements from 0 to about 100 GPa and shock wave (SW) measurement at only one pressure of about 390 GPa by comparison with visual extrapolation, we perform SW experiments to replenish more T m data on purpose to make this comparison more directly and rationally as well. The techniques adopted consist of Hügoniot sound velocity measurement for porous Mo and shock-induced release T m measurements for both solid and porous Mo. Totally five SW T m data, which extends the measured pressure range from previous about 390 GPa down to about 136 GPa that is close to the highest pressure (about 100 GPa) attained by previous DAC experiments, are therefore obtained. These measured Tm data, other than the extrapolated as mentioned above, exhibit a manner of continuous variation with pressure and can be fitted well with Lindemann melting description. More significantly, the measured T m data at lowest pressure are still much higher than that of the DACs and the overall trend of these T m data is against to the two-segment melting curve model, with a sudden change in dT m /d P at about 210 GPa, previously proposed by Errandonea [Physica B 357 (2005) 356]. Though the problem of large discrepancy in T m data measured between DAC and SW has not been completely explained, our knowledge on this matter achieves indubitable progress since it is of value to programme the next clarification. Some suggestions for further clarifying the issue of large discrepancy between DAC and SW measurements are also proposed. (condensed matter: structure, mechanical and thermal properties)

Cures for the shock instability: Development of a shock-stable Roe scheme

CERN Document Server

Kim, S S; Rho, O H; Kyu-Hong, S

2003-01-01

This paper deals with the development of an improved Roe scheme that is free from the shock instability and still preserves the accuracy and efficiency of the original Roe's Flux Difference Splitting (FDS). Roe's FDS is known to possess good accuracy but to suffer from the shock instability, such as the carbuncle phenomenon. As the first step towards a shock-stable scheme, Roe's FDS is compared with the HLLE scheme to identify the source of the shock instability. Through a linear perturbation analysis on the odd-even decoupling problem, damping characteristic is examined and Mach number-based functions f and g are introduced to balance damping and feeding rates, which leads to a shock-stable Roe scheme. In order to satisfy the conservation of total enthalpy, which is crucial in predicting surface heat transfer rate in high-speed steady flows, an analysis of dissipation mechanism in the energy equation is carried out to find out the error source and to make the proposed scheme preserve total enthalpy. By modif...

Shock compression of monocrystalline copper: Experiments, characterization, and analysis

International Nuclear Information System (INIS)

Cao Buyang; Lassila, David H.; Huang Chongxiang; Xu Yongbo; Meyers, Marc Andre

2010-01-01

Monocrystalline copper samples with [0 0 1] and [2 2 1] orientations were subjected to shock/recovery experiments at 30 and 57 GPa and 90 K. The slip system activity and the microstructural evolution were investigated. Different defect structures, including dislocations, stacking faults, twins, microbands, and recrystallized grains were observed in the specimens. The residual microstructures were dependent on crystalline orientation and pressure. The differences with crystalline orientations are most likely due to different resolved shear stresses on specific crystalline planes. The geometric relationships between the shock propagation direction and crystalline orientation are presented under uniaxial strain. It is shown that the [2 2 1] orientation, by virtue of having fewer highly activated slip systems, exhibits greater concentration of deformation with more intense shear on the primary system. This, in turn leads to greater local temperature rise and full recrystallization, in spite of the thermodynamic residual temperature of ∼500 K and rapid cooling (within 20 s) to ambient temperature. The profuse observation of microbands is interpreted in terms of the mechanism proposed by Huang and Gray [J.C. Huang, G.T. Gray III, Acta Metallurgica 37 (1989) 3335-3347].

Thermal shock experiment analysis, the use of crack arrest toughness measurements

International Nuclear Information System (INIS)

Miannay, D.; Pellissier-Tanon, A.; Chavaillard, J.P.

1984-06-01

The main purpose of thermal shock experiment is to assess the procedure codified in the ASME XI appendix 1 or RCC-M-B appendix ZG, and allow comparisons with numerical simulations. The analysis of the integrity of the PWR vessel belt line under accidental transients is based on reference curves. The test-piece is a cylinder of SA 508 cl.3 steel. Arrest toughness measured agrees with reference curve

Shock-induced devolatilization of calcite

Science.gov (United States)

Boslough, M. B.; Ahrens, T. J.; Vizgirda, J.; Becker, R. H.; Epstein, S.

1982-01-01

Experimental measurements of the release adiabats by Vizgirda (1981) indicate that substantial vaporization takes place upon release from shock pressures of 37 GPa for calcite and 14 GPa for aragonite. The present investigation includes the first controlled partial vaporization experiments on calcite. The experiments were conducted to test the predictions of the release adiabat experiments. The quantities of the gaseous species produced from shocked calcite and their carbon and oxygen isotopic compositions were determined, and the shock-induced effect on the Mn(2+) electron spin resonance spectrum in the shock-recovered calcite was observed. On the basis of the obtained results, it is concluded that shock stresses at the 17-18 GPa level give rise to volatilization of 0.03-0.3 (mole) percent of calcite to CO2 and CO. The devolatilization of calcite occurs at low pressure at significantly lower entropy densities than predicted on the basis of thermodynamic continuum models.

A re-examination of two-step lateral stress history in silicon carbide

International Nuclear Information System (INIS)

Dandekar, Dattatraya P.

2004-01-01

The observed two-step lateral stress history in silicon carbide, SiC-B under plane shock wave propagation [N. K. Bourne, J. Millett, and I. Pickup, J. Appl. Phys. 81, 6019 (1997)] is attributed to a delayed failure in SiC-B due to propagation of a slow moving front traveling behind the main shock wave. According to this attribution, the first lower magnitude, step corresponds to the lateral stress in intact shock compressed silicon carbide as a result of the fast moving plane shock wave. The second step of higher magnitude, observed after a few hundred nanoseconds, corresponds to the lateral stress in failed silicon carbide due to propagation of the slower moving front. The current analysis, takes into account additional relevant existing results dealing with shock response of SiC-B, and shows that the suggested explanation for the observed phenomenon remains in doubt

Walter B. Cannon's World War I experience: treatment of traumatic shock then and now.

Science.gov (United States)

Ryan, Kathy L

2018-06-01

Walter B. Cannon (1871-1945), perhaps America's preeminent physiologist, volunteered for service with the Army Expeditionary Force (AEF) during World War I. He initially served with Base Hospital No. 5, a unit made up of Harvard clinicians, before moving forward to the front lines to serve at a casualty clearing station run by the British. During his time there, he performed research on wounded soldiers to understand the nature and causes of traumatic shock. Subsequently, Cannon performed animal experimentation on the causes of traumatic shock in the London laboratory of Dr. William Bayliss before being assigned to the AEF Central Medical Laboratory in Dijon, France, where he continued his experimental studies. During this time, he also developed and taught a curriculum on resuscitation of wounded soldiers to medical providers. Although primarily a researcher and teacher, Cannon also performed clinical duties throughout the war, serving with distinction under fire. After the war, Cannon wrote a monograph entitled Traumatic Shock (New York: Appleton, 1923), which encapsulated the knowledge that had been gained during the war, both from direct observation of wounded soldiers, as well as laboratory experimentation on the causes and treatment of traumatic shock. In his monograph, Cannon elucidates a number of principles concerning hemorrhagic shock that were later forgotten, only to be "rediscovered" during the current conflicts in Iraq and Afghanistan. This paper summarizes Cannon's wartime experiences and the knowledge gained concerning traumatic shock during World War I, with a comparison of current combat casualty care practices and knowledge to that which Cannon and his colleagues understood a century ago.

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

Science.gov (United States)

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.

Holographic interferometric observation of shock wave focusing to extracorporeal shock wave lithotripsy

Science.gov (United States)

Takayama, Kazuyoshi; Obara, Tetsuro; Onodera, Osamu

1991-04-01

Underwater shock wave focusing is successfully applied to disintegrate and remove kidney stones or gallbladder stones without using surgical operations. This treatment is one of the most peaceful applications ofshock waves and is named as the Extracorporeal Shock Wave Lithotripsy. Ajoint research project is going on between the Institute ofFluid Science, Tohoku University and the School ofMedicine, Tohoku University. The paper describes a result of the fundamental research on the underwater shock wave focusing applied to the ESWL. Quantitatively to visualize the underwater shock waves, various optical flow visualization techniques were successfully used such as holographic interferometry, and shadowgraphs combined with Ima-Con high speed camera. Double exposure holographic interferometric observation revealed the mechanism of generation, propagation and focusing of underwater shock waves. The result of the present research was already used to manufacture a prototype machine and it has already been applied successfully to ESWL crinical treatments. However, despite of success in the clinical treatments, important fundamental questions still remain unsolved, i.e., effects of underwater shock wave focusing on tissue damage during the treatment. Model experiments were conducted to clarify mechanism of the tissue damage associated with the ESWL. Shock-bubble interactions were found responsible to the tissue damage during the ESWL treatment. In order to interprete experimental findings and to predict shock wave behavior and high pressures, a numerical simulation was carried. The numerical results agreed with the experiments.

3D Simulations of the ``Keyhole'' Hohlraum for Shock Timing on NIF

Science.gov (United States)

Robey, H. F.; Marinak, M. M.; Munro, D. H.; Jones, O. S.

2007-11-01

Ignition implosions planned for the National Ignition Facility (NIF) require a pulse shape with a carefully designed series of steps, which launch a series of shocks through the ablator and DT fuel. The relative timing of these shocks must be tuned to better than +/- 100ps to maintain the DT fuel on a sufficiently low adiabat. To meet these requirements, pre-ignition tuning experiments using a modified hohlraum geometry are being planned. This modified geometry, known as the ``keyhole'' hohlraum, adds a re-entrant gold cone, which passes through the hohlraum and capsule walls, to provide an optical line-of-sight to directly measure the shocks as they break out of the ablator. In order to assess the surrogacy of this modified geometry, 3D simulations using HYDRA [1] have been performed. The drive conditions and the resulting effect on shock timing in the keyhole hohlraum will be compared with the corresponding results for the standard ignition hohlraum. [1] M.M. Marinak, et al., Phys. Plasmas 8, 2275 (2001).

Observation of Self-Cavitating Envelope Dispersive Shock Waves in Yttrium Iron Garnet Thin Films

Science.gov (United States)

Janantha, P. A. Praveen; Sprenger, Patrick; Hoefer, Mark A.; Wu, Mingzhong

2017-07-01

The formation and properties of envelope dispersive shock wave (DSW) excitations from repulsive nonlinear waves in a magnetic film are studied. Experiments involve the excitation of a spin wave step pulse in a low-loss magnetic Y3Fe5O12 thin film strip, in which the spin wave amplitude increases rapidly, realizing the canonical Riemann problem of shock theory. Under certain conditions, the envelope of the spin wave pulse evolves into a DSW that consists of an expanding train of nonlinear oscillations with amplitudes increasing from front to back, terminated by a black soliton. The onset of DSW self-cavitation, indicated by a point of zero power and a concomitant 180° phase jump, is observed for sufficiently large steps, indicative of the bidirectional dispersive hydrodynamic nature of the DSW. The experimental observations are interpreted with theory and simulations of the nonlinear Schrödinger equation.

Attenuation of shock waves in copper and stainless steel

International Nuclear Information System (INIS)

Harvey, W.B.

1986-06-01

By using shock pins, data were gathered on the trajectories of shock waves in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). Shock pressures were generated in these materials by impacting the appropriate target with thin (approx.1.5 mm) flying plates. The flying plates in these experiments were accelerated to high velocities (approx.4 km/s) by high explosives. Six experiments were conducted, three using SS-304L as the target material and three experiments using OFHC-Cu as the target material. Peak shock pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak shock pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the shock wave by a following release wave was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the shock waves was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated shock trajectories to the experimental data. Based on such comparisons, the conclusion can be drawn that OFHC-Cu enters a melt phase at about 130 GPa on the principal Hugoniot. There was no sign of phase changes in the stainless-steel experiments. In order to match the observed attenuation of the shock waves in the SS-304L experiments, it was necessary to include strength effects in the calculations. It was found that the values for the parameters in the strength equations were dependent on the equation of state used in the modeling of the experiments. 66 refs., 194 figs., 77 tabs

Attenuation of shock waves in copper and stainless steel

Energy Technology Data Exchange (ETDEWEB)

Harvey, W.B.

1986-06-01

By using shock pins, data were gathered on the trajectories of shock waves in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). Shock pressures were generated in these materials by impacting the appropriate target with thin (approx.1.5 mm) flying plates. The flying plates in these experiments were accelerated to high velocities (approx.4 km/s) by high explosives. Six experiments were conducted, three using SS-304L as the target material and three experiments using OFHC-Cu as the target material. Peak shock pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak shock pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the shock wave by a following release wave was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the shock waves was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated shock trajectories to the experimental data. Based on such comparisons, the conclusion can be drawn that OFHC-Cu enters a melt phase at about 130 GPa on the principal Hugoniot. There was no sign of phase changes in the stainless-steel experiments. In order to match the observed attenuation of the shock waves in the SS-304L experiments, it was necessary to include strength effects in the calculations. It was found that the values for the parameters in the strength equations were dependent on the equation of state used in the modeling of the experiments. 66 refs., 194 figs., 77 tabs.

Experimental investigation of shock wave - bubble interaction

Energy Technology Data Exchange (ETDEWEB)

Alizadeh, Mohsen

2010-04-09

In this work, the dynamics of laser-generated single cavitation bubbles exposed to lithotripter shock waves has been investigated experimentally. The energy of the impinging shock wave is varied in several steps. High-speed photography and pressure field measurements simultaneously with image acquisition provide the possibility of capturing the fast bubble dynamics under the effect of the shock wave impact. The pressure measurement is performed using a fiber optic probe hydrophone (FOPH) which operates based on optical diagnostics of the shock wave propagating medium. After a short introduction in chapter 1 an overview of the previous studies in chapter 2 is presented. The reported literatures include theoretical and experimental investigations of several configurations of physical problems in the field of bubble dynamics. In chapter 3 a theoretical description of propagation of a shock wave in a liquid like water has been discussed. Different kinds of reflection of a shock wave at an interface are taken into account. Undisturbed bubble dynamics as well as interaction between a planar shock wave and an initially spherical bubble are explored theoretically. Some physical parameters which are important in this issue such as the velocity of the shock-induced liquid jet, Kelvin impulse and kinetic energy are explained. The shock waves are generated in a water filled container by a focusing piezoelectric generator. The shock wave profile has a positive part with pulse duration of ∼1 μs followed by a longer tension tail (i.e. ∼3 μs). In chapter 4 high-speed images depict the propagation of a shock wave in the water filled tank. The maximum pressure is also derived for different intensity levels of the shock wave generator. The measurement is performed in the free field (i.e. in the absence of laser-generated single bubbles). In chapter 5 the interaction between lithotripter shock waves and laserinduced single cavitation bubbles is investigated experimentally. An

Shock drift acceleration in the presence of waves

Science.gov (United States)

Decker, R. B.; Vlahos, L.

1985-01-01

Attention is given to the initial results of a model designed to study the modification of the scatter-free, shock drift acceleration of energetic test particles by wave activity in the vicinity of a quasi-perpendicular, fast-mode MHD shock. It is emphasized that the concept of magnetic moment conservation is a valid approximation only in the perpendicular and nearly perpendicular regimes, when the angle theta-Bn between the shock normal and the upstream magnetic field vector is in the range from 70 deg to 90 deg. The present investigation is concerned with one step in a program which is being developed to combine the shock drift and diffusive processes at a shock of arbitrary theta-Bn.

Thermodynamically Based Equation of State for Shock Wave Studies : Application to the Design of Experiments on Tin

International Nuclear Information System (INIS)

Buy, Francois; Voltz, Christophe; Llorca, Fabrice

2006-01-01

This work is devoted to the evaluation of complex behavior of metals under shock wave loading. It presents a methodology for the design of specific experiments performed for validation of models and the evaluation of a multiphase equation of state for tin. This material has been selected because of the numerous works completed during the past years on its equation of state. We focus on the solid diagram which presents two solid phases. A thermodynamically based equation of state is developed which gives the opportunity to search for singularities which could be activated under particular shock wave loading. In the temperature -- pressure diagram, the superimposed Hugoniot and release paths make apparent a double shock, release shock configurations. We propose the design and the VISAR results of a calibrated shock -- reshock test for investigating the validity and the efficiency of the model for predicting the thermodynamical state of tin (phases mixing, temperature...). Comparison between numerical and experimental data shows the good accuracy of the results given by the EOS

Effects of Atwood number on shock focusing in shock-cylinder interaction

Science.gov (United States)

Ou, Junfeng; Ding, Juchun; Luo, Xisheng; Zhai, Zhigang

2018-02-01

The evolution of shock-accelerated heavy-gas cylinder surrounded by the air with different Atwood numbers (A_t=0.28, 0.50, 0.63) is investigated, concentrating on shock focusing and jet formation. Experimentally, a soap film technique is used to generate an ideal two-dimensional discontinuous gas cylinder with a clear surface, which can guarantee the observation of shock wave movements inside the cylinder. Different Atwood numbers are realized by different mixing ratios of SF_6 and air inside the cylinder. A high-speed schlieren system is adopted to capture the shock motions and jet morphology. Numerical simulations are also performed to provide more information. The results indicate that an inward jet is formed for low Atwood numbers, while an outward jet is generated for high Atwood numbers. Different Atwood numbers will lead to the differences in the relative velocities between the incident shock and the refraction shock, which ultimately results in the differences in shock competition near the downstream pole. The morphology and feature of the jet are closely associated with the position and intensity of shock focusing. The pressure and vorticity contours indicate that the jet formation should be attributed to the pressure pulsation caused by shock focusing, and the jet development is ascribed to the vorticity induction. Finally, a time ratio proposed in the previous work for determining the shock-focusing type is verified by experiments.

International Students from Melbourne Describing Their Cross-Cultural Transitions Experiences: Culture Shock, Social Interaction, and Friendship Development

Science.gov (United States)

Belford, Nish

2017-01-01

Drawing from a study that explored how international students experience cross-cultural transitions after living and studying in Melbourne for a few years, this paper, in particular, examines the participants' experiences with culture shock, social interaction, and friendship development. The findings include narratives of their personal stories…

Laser-driven Mach waves for gigabar-range shock experiments

Science.gov (United States)

Swift, Damian; Lazicki, Amy; Coppari, Federica; Saunders, Alison; Nilsen, Joseph

2017-10-01

Mach reflection offers possibilities for generating planar, supported shocks at higher pressures than are practical even with laser ablation. We have studied the formation of Mach waves by algebraic solution and hydrocode simulation for drive pressures at much than reported previously, and for realistic equations of state. We predict that Mach reflection continues to occur as the drive pressure increases, and the pressure enhancement increases monotonically with drive pressure even though the ``enhancement spike'' characteristic of low-pressure Mach waves disappears. The growth angle also increases monotonically with pressure, so a higher drive pressure seems always to be an advantage. However, there are conditions where the Mach wave is perturbed by reflections. We have performed trial experiments at the Omega facility, using a laser-heated halfraum to induce a Mach wave in a polystyrene cone. Pulse length and energy limitations meant that the drive was not maintained long enough to fully support the shock, but the results indicated a Mach wave of 25-30 TPa from a drive pressure of 5-6 TPa, consistent with simulations. A similar configuration should be tested at the NIF, and a Z-pinch driven configuration may be possible. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Study of shock coalescence in laser-irradiated targets

International Nuclear Information System (INIS)

Coe, S.E.; Willi, O.; Afshar-Rad, T.; Rose, S.J.

1988-01-01

We report on the first direct experimental observation of the coalescence of two shocks induced by a shaped laser pulse. Optical streak photography of the rear surface of aluminum multiple step targets was used to study the breakout of these shocks and observe their behavior. The experimental results are compared with simulations by a one-dimensional Lagrangian hydrodynamic code

A step-by-step experiment of 3C-SiC hetero-epitaxial growth on 4H-SiC by CVD

Energy Technology Data Exchange (ETDEWEB)

Xin, Bin [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Jia, Ren-Xu, E-mail: rxjia@mail.xidian.edu.cn [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Hu, Ji-Chao [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Tsai, Cheng-Ying [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan (China); Lin, Hao-Hsiung, E-mail: hhlin@ntu.edu.tw [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan (China); Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 10617 Taipei, Taiwan (China); Zhang, Yu-Ming [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China)

2015-12-01

Highlights: • A step-by-step experiment to investigate the growth mechanism of SiC hetero-epitaxial is proposed. • It has shown protrusive regular “hill” morphology with much lower density of DPB defect in our experiment, which normally were in high density with shallow groove. Based on the defect morphology, an anisotropy migration rate phenomenon of adatoms has been regarded as forming the morphology of DPB defects and a new “DPB defects assist epitaxy” growth mode has been proposed based on Frank-van der Merwe growth mode. - Abstract: To investigate the growth mechanism of hetero-epitaxial SiC, a step-by-step experiment of 3C-SiC epitaxial layers grown on 4H-SiC on-axis substrates by the CVD method are reported in this paper. Four step experiments with four one-quarter 4H-SiC wafers were performed. Optical microscopy and atomic force microscopy (AFM) were used to characterize the morphology of the epitaxial layers. It was previously found that the main factor affecting the epilayer morphology was double-positioning boundary (DPB) defects, which normally were in high density with shallow grooves. However, a protrusive regular “hill” morphology with a much lower density was shown in our experiment in high-temperature growth conditions. The anisotropic migration of adatoms is regarded as forming the morphology of DPB defects, and a new “DPB defects assist epitaxy” growth mode has been proposed based on the Frank-van der Merwe growth mode. Raman spectroscopy and X-ray diffraction were used to examine the polytypes and the quality of the epitaxial layers.

High temperature superconducting Josephson transmission lines for pulse and step sharpening

International Nuclear Information System (INIS)

Martens, J.S.; Wendt, J.R.; Hietala, V.M.; Ginley, D.S.; Ashby, C.I.H.; Plut, T.A.; Vawter, G.A.; Tigges, C.P.; Siegal, M.P.; Hou, S.Y.; Phillips, J.M.; Hohenwarter, G.K.G.

1992-01-01

An increasing number of high speed digital and other circuit applications require very narrow impulses or rapid pulse edge transitions. Shock wave transmission lines using series or shunt Josephson junctions are one way to generate these signals. Using two different high temperature superconducting Josephson junction processes (step-edge and electron beam defined nanobridges), such transmission lines have been constructed and tested at 77 K. Shock wave lines with approximately 60 YBaCuO nanobridges, have generated steps with fall times of about 10 ps. With step-edge junctions (with higher figures of merit but lower uniformity), step transition times have been reduced to an estimated 1 ps

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

International Nuclear Information System (INIS)

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

2015-01-01

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

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

Science.gov (United States)

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

2015-12-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Pak, A.; Dewald, E. L.; Landen, O. L.; Milovich, J.; Strozzi, D. J.; Berzak Hopkins, L. F.; Bradley, D. K.; Divol, L.; Ho, D. D.; MacKinnon, A. J.; Meezan, N. B.; Michel, P.; Moody, J. D.; Moore, A. S.; Schneider, M. B.; Town, R. P. J.; Hsing, W. W.; Edwards, M. J. [Lawrence Livermore National Laboratory, Livermore, California, 94550 (United States)

2015-12-15

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

Collisionless Electrostatic Shock Modeling and Simulation

Science.gov (United States)

2016-10-21

equations with piston -like boundary conditions gives a solution for the shock behavior. • Assumes cold upstream ions, therefore neglecting shock...temperature ratio (>10) – Wave Train Wavelength – Shock-Front Mach Number – Reflected Ion Beam Velocity Gathering Experiment Data – Double Plasma Device...experimental shock data. • Inconsistencies in published 1969 double -plasma device data hampered validation. Future Work: Extension to Moderately

Delayed Failure in a Shock Loaded Alumina

International Nuclear Information System (INIS)

Cooper, G. A.; Millett, J. C. F.; Bourne, N. K.; Dandekar, D. P.

2006-01-01

Manganin stress gauges have been used to measure the lateral stress in a shock-loaded alumina. In combination with known longitudinal stresses, these have been used to determine the shear strength of this material, behind the shock front. The two-step nature of the lateral stress traces shows a slow moving front behind the main shock, behind which shear strength undergoes a significant decrease. Results also show that this front decreases markedly in velocity as the HEL is crossed, suggesting that limited plasticity occurs during inelastic deformation. Finally, comparison of measured shear strengths with other aluminas shows a high degree of agreement

Cardiogenic shock. Current concepts in management.

Science.gov (United States)

Balakumaran, K; Hugenholtz, P G

1986-10-01

This article presents a categorisation of circulatory shock and discusses the causes, haemodynamics, and clinical recognition of cardiogenic shock. The first step in the management strategy in cardiogenic shock is to guide the patient from the state of shock to one of managed haemodynamic stability. The therapeutic manoeuvres of this first step constitute the management tactics, which can be grouped under 3 general headings: (a) making the most of a malfunctioning heart; (b) improving the state of the heart; and (c) reducing the demands on the heart. In order to make the most of the heart, i.e. to get the highest possible output at the lowest possible cost, clinicians need to use their judgement in stimulating an overtaxed heart on the one hand, and in manipulating the loads on it (the preload and afterload) on the other, for although these methods may be advantageous, they are not without their pitfalls. Efforts to improve the state of the heart often necessitate surgical (e.g. mitral valve replacement) or semisurgical (e.g. coronary angiography and recanalisation) techniques, although intravenous antithrombotic agents may achieve comparable results in a few cases at the bedside. Reducing the demands on the heart is an active process involving the takeover of at least a part of the work of the heart by ancillary devices such as the intra-aortic balloon pump, and of the work of breathing by intubation and artificial ventilation. The individuality of each case of cardiogenic shock emphasises the need for empirical modulation of therapy based on feedback information obtained by haemodynamic monitoring.

Shock compression of diamond crystal

OpenAIRE

Kondo, Ken-ichi; Ahrens, Thomas J.

1983-01-01

Two shock wave experiments employing inclined mirrors have been carried out to determine the Hugoniot elastic limit (HEL), final shock state at 191 and 217 GPa, and the post-shock state of diamond crystal, which is shock-compressed along the intermediate direction between the and crystallographic axes. The HEL wave has a velocity of 19.9 ± 0.3 mm/µsec and an amplitude of 63 ± 28 GPa. An alternate interpretation of the inclined wedge mirror streak record suggests a ramp precursor wave and th...

Experiments on ion-acoustic shock waves in a dusty plasma

International Nuclear Information System (INIS)

Nakamura, Y.

2002-01-01

Dust ion-acoustic shock waves have been investigated experimentally in a homogeneous unmagnetized dusty double-plasma device. An initial compressional wave with a ramp shape steepens to form oscillations at the leading part due to dispersion. The oscillation develops to a train of solitons when the plasma contains no dust grain. The wave becomes an oscillatory shock wave when the dust is mixed in the plasma and the density of the dust grains is smaller than a critical value. When the dust density is larger than the critical value, only steepening is observed at the leading part of the wave and a monotonic shock structure is observed. The velocity and width of the shock waves are measured and compared with results of numerical integrations of the modified Korteweg-de Vries-Burgers equation

Piecewise parabolic method for simulating one-dimensional shear shock wave propagation in tissue-mimicking phantoms

Science.gov (United States)

Tripathi, B. B.; Espíndola, D.; Pinton, G. F.

2017-11-01

The recent discovery of shear shock wave generation and propagation in the porcine brain suggests that this new shock phenomenology may be responsible for a broad range of traumatic injuries. Blast-induced head movement can indirectly lead to shear wave generation in the brain, which could be a primary mechanism for injury. Shear shock waves amplify the local acceleration deep in the brain by up to a factor of 8.5, which may tear and damage neurons. Currently, there are numerical methods that can model compressional shock waves, such as comparatively well-studied blast waves, but there are no numerical full-wave solvers that can simulate nonlinear shear shock waves in soft solids. Unlike simplified representations, e.g., retarded time, full-wave representations describe fundamental physical behavior such as reflection and heterogeneities. Here we present a piecewise parabolic method-based solver for one-dimensional linearly polarized nonlinear shear wave in a homogeneous medium and with empirical frequency-dependent attenuation. This method has the advantage of being higher order and more directly extendable to multiple dimensions and heterogeneous media. The proposed numerical scheme is validated analytically and experimentally and compared to other shock capturing methods. A Riemann step-shock problem is used to characterize the numerical dissipation. This dissipation is then tuned to be negligible with respect to the physical attenuation by choosing an appropriate grid spacing. The numerical results are compared to ultrasound-based experiments that measure planar polarized shear shock wave propagation in a tissue-mimicking gelatin phantom. Good agreement is found between numerical results and experiment across a 40 mm propagation distance. We anticipate that the proposed method will be a starting point for the development of a two- and three-dimensional full-wave code for the propagation of nonlinear shear waves in heterogeneous media.

Investigation of shock compressed plasma parameters by interaction with magnetic field

International Nuclear Information System (INIS)

Dudin, S. V.; Fortov, V. E.; Gryaznov, V. K.; Mintsev, V. B.; Shilkin, N. S.; Ushnurtsev, A. E.

1998-01-01

The Hall effect parameters in shock compressed air, helium and xenon have been estimated and results of experiments with air and helium plasma are presented. Explosively driven shock tubes were used for the generation of strong shock waves. To obtain magnetic field a solenoid was winded over the shock tube. Calculations of dense shock compressed plasma parameters were carried out to plan the experiments. In the experiments with the magnetic field of ∼5 T it was found, that air plasma slug was significantly heated by the whirlwind electrical field. The reflected shock waves technique was used in the experiments with helium. Results on measurements of electrical conductivity and electron concentration of helium are presented

Do structural oil-market shocks affect stock prices?

International Nuclear Information System (INIS)

Apergis, Nicholas; Miller, Stephen M.

2009-01-01

This paper investigates how explicit structural shocks that characterize the endogenous character of oil price changes affect stock-market returns in a sample of eight countries - Australia, Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States. For each country, the analysis proceeds in two steps. First, modifying the procedure of Kilian [Not All Oil Price Shocks are Alike: Disentangling Demand and Supply Shocks in the Crude Oil Market. American Economic Review.], we employ a vector error-correction or vector autoregressive model to decompose oil-price changes into three components: oil-supply shocks, global aggregate-demand shocks, and global oil-demand shocks. The last component relates to specific idiosyncratic features of the oil market, such as changes in the precautionary demand concerning the uncertainty about the availability of future oil supplies. Second, recovering the oil-supply shocks, global aggregate-demand shocks, and global oil-demand shocks from the first analysis, we then employ a vector autoregressive model to determine the effects of these structural shocks on the stock market returns in our sample of eight countries. We find that international stock market returns do not respond in a large way to oil market shocks. That is, the significant effects that exist prove small in magnitude. (author)

New Bayesian inference method using two steps of Markov chain Monte Carlo and its application to shock tube experiment data of Furan oxidation

KAUST Repository

Kim, Daesang; El Gharamti, Iman; Bisetti, Fabrizio; Farooq, Aamir; Knio, Omar

2016-01-01

A new Bayesian inference method has been developed and applied to Furan shock tube experimental data for efficient statistical inferences of the Arrhenius parameters of two OH radical consumption reactions. The collected experimental data, which

Shock compression of glow discharge polymer (GDP): density functional theory (DFT) simulations and experiments on Sandia's Z-machine

Science.gov (United States)

Mattsson, Thomas R.; Cochrane, K. R.; Ao, T.; Lemke, R. W.; Flicker, D. G.; Schoff, M. E.; Blue, B. E.; Hamel, S.; Herrmann, M. C.

2015-11-01

Glow discharge polymer (GDP) is used extensively as capsule/ablation material in inertial confinement fusion (ICF) capsules. Accurate knowledge of the equation of state (EOS) under shock and release is particularly important for high-fidelity design, analysis, and optimization of ICF experiments since the capsule material is subject to several converging shocks as well as release towards the cryogenic fuel. We performed Density Functional Theory (DFT) based quantum molecular dynamics (QMD) simulations, to gain knowledge of the behavior of GDP - including the effect of changes in chemical composition. The shock pressures calculated from DFT are compared experimental data taken on magnetically launched flyer plate impact experiments on at Sandia's Z-machine. Large GDP samples were grown in a planar geometry to improve the sample quality and maintained in a nitrogen atmosphere following manufacturing, thus allowing for a direct comparison to the DFT/QMD simulations. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under contract DE-AC04-94AL85000.

Numerical analysis of experiments on the generation of shock waves in aluminium under indirect (X-ray) action on the Iskra-5 facility

Energy Technology Data Exchange (ETDEWEB)

Bondarenko, S V; Dolgoleva, G V; Novikova, E A

2013-07-31

The dynamics of laser and X-ray radiation fields in experiments with cylindrical converter boxes (illuminators), which had earlier been carried out on the Iskra-5 laser facility (the second harmonic of iodine laser radiation, {lambda} = 0.66 {mu}m) was investigated in a sector approximation using the SND-LIRA numerical technique. In these experiments, the X-ray radiation temperature in the box was determined by measuring the velocity of the shock wave generated in the sample under investigation, which was located at the end of the cylindrical illuminator. Through simulations were made using the SND-LIRA code, which took into account the absorption of laser driver radiation at the box walls, the production of quasithermal radiation, as well as the formation and propagation of the shock wave in the sample under investigation. An analysis of the experiments permits determining the electron thermal flux limiter f: for f = 0.03 it is possible to match the experimental scaling data for X-ray in-box radiation temperature to the data of our simulations. The shock velocities obtained from the simulations are also consistent with experimental data. In particular, in the experiment with six laser beams (and a laser energy E{sub L} = 1380 J introduced into the box) the velocity of the shock front (determined from the position of a laser mark) after passage through a 50-{mu}m thick base aluminium layer was equal to 35{+-}1.6 km s{sup -1}, and in simulations to 36 km s{sup -1}. In the experiment with four laser beams (for E{sub L} = 850 J) the shock velocity (measured from the difference of transit times through the base aluminium layer and an additional thin aluminium platelet) was equal to 30{+-}3.6 km s{sup -1}, and in simulations to 30 km s{sup -1}. (interaction of laser radiation with matter)

Composition of the earth's atmosphere by shock-layer radiometry during the PAET entry probe experiment.

Science.gov (United States)

Whiting, E. E.; Arnold, J. O.; Page, W. A.; Reynolds, R. M.

1973-01-01

A determination of the composition of the earth's atmosphere obtained from onboard radiometer measurements of the spectra emitted from the bow shock layer of a high-speed entry probe is reported. The N2, O2, CO2, and noble gas concentrations in the earth's atmosphere were determined to good accuracy by this technique. The results demonstrate unequivocally the feasibility of determining the composition of an unknown planetary atmosphere by means of a multichannel radiometer viewing optical emission from the heated atmospheric gases in the region between the bow shock wave and the vehicle surface. The spectral locations in this experiment were preselected to enable the observation of CN violet, N2(+) first negative and atomic oxygen emission at 3870, 3910, and 7775 A, respectively. The atmospheric gases were heated and compressed by the shock wave to a peak temperature of about 6100 K and a corresponding pressure of 0.4 atm. Complete descriptions of the data analysis technique and the onboard radiometer and its calibration are given.

Double Shock Experiments Performed at -55°C on LX-17 with Reactive Flow Modeling to Understand the Reacted Equation of State

Science.gov (United States)

Dehaven, Martin R.; Vandersall, Kevin S.; Strickland, Shawn L.; Fried, Laurence E.; Tarver, Craig M.

2017-06-01

Experiments were performed at -55°C to measure the reacted state of LX-17 (92.5% TATB and 7.5% Kel-F by weight) using a double shock technique using two flyer materials (with known properties) mounted on a projectile that send an initial shock through the material close to the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. Information on the reacted state is obtained by measuring the relative timing and magnitude of the first and second shock waves. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include a comparison to prior work at ambient temperature, the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

High temperature shock tube experiments and kinetic modeling study of diisopropyl ketone ignition and pyrolysis

KAUST Repository

Barari, Ghazal; Pryor, Owen; Koroglu, Batikan; Sarathy, Mani; Masunov, Artë m E.; Vasu, Subith S.

2017-01-01

Diisopropyl ketone (DIPK) is a promising biofuel candidate, which is produced using endophytic fungal conversion. In this work, a high temperature detailed combustion kinetic model for DIPK was developed using the reaction class approach. DIPK ignition and pyrolysis experiments were performed using the UCF shock tube. The shock tube oxidation experiments were conducted between 1093K and 1630K for different reactant compositions, equivalence ratios (φ=0.5–2.0), and pressures (1–6atm). In addition, methane concentration time-histories were measured during 2% DIPK pyrolysis in argon using cw laser absorption near 3400nm at temperatures between 1300 and 1400K near 1atm. To the best of our knowledge, current ignition delay times (above 1050K) and methane time histories are the first such experiments performed in DIPK at high temperatures. Present data were used as validation targets for the new kinetic model and simulation results showed fair agreement compared to the experiments. The reaction rates corresponding to the main consumption pathways of DIPK were found to have high sensitivity in controlling the reactivity, so these were adjusted to attain better agreement between the simulation and experimental data. A correlation was developed based on the experimental data to predict the ignition delay times using the temperature, pressure, fuel concentration and oxygen concentration.

High temperature shock tube experiments and kinetic modeling study of diisopropyl ketone ignition and pyrolysis

KAUST Repository

Barari, Ghazal

2017-03-10

Diisopropyl ketone (DIPK) is a promising biofuel candidate, which is produced using endophytic fungal conversion. In this work, a high temperature detailed combustion kinetic model for DIPK was developed using the reaction class approach. DIPK ignition and pyrolysis experiments were performed using the UCF shock tube. The shock tube oxidation experiments were conducted between 1093K and 1630K for different reactant compositions, equivalence ratios (φ=0.5–2.0), and pressures (1–6atm). In addition, methane concentration time-histories were measured during 2% DIPK pyrolysis in argon using cw laser absorption near 3400nm at temperatures between 1300 and 1400K near 1atm. To the best of our knowledge, current ignition delay times (above 1050K) and methane time histories are the first such experiments performed in DIPK at high temperatures. Present data were used as validation targets for the new kinetic model and simulation results showed fair agreement compared to the experiments. The reaction rates corresponding to the main consumption pathways of DIPK were found to have high sensitivity in controlling the reactivity, so these were adjusted to attain better agreement between the simulation and experimental data. A correlation was developed based on the experimental data to predict the ignition delay times using the temperature, pressure, fuel concentration and oxygen concentration.

Composite Liner, Multi-Megabar Shock Driver Development

International Nuclear Information System (INIS)

Cochrane, J.C. Jr.; Bartsch, R.R.; Clark, D.A.; Morgan, D.V.; Anderson, W.E.; Lee, H.; Bowers, R.L.; Atchison, W.L.; Oona, H.; Stokes, J.L.; Veeser, L.R.; Broste, W.B.

1998-01-01

The multi-megabar shock driver development is a series of experiments in support of the Los Alamos High Energy Density Physics Experimental Program. Its purpose is to develop techniques to impact a uniform, stable, composite liner upon a high Z target to produce a multi-megabar shock for EOS studies. To date, experiments have been done on the Pegasus II capacitor bank with a current of approximately12MA driving the impactor liner. The driving field is approximately200 T at the target radius of 1cm. Data will be presented on the impactor liner. The driving field is approximately200 T at the target radius of 1 cm. Data will be presented on the stability and uniformity of the impactor liner when it impacts the target cylinder. Three experiments have been done with emphasis on liner development. Shock pressures greater than a megabar have been done with emphasis on liner development. Shock pressures greater than a megabar have been produced with an Al target cylinder. A Pt target cylinder should produce shock pressures in th e 5-megabar range

High-Gain Shock Ignition on the National Ignition Facility

Science.gov (United States)

Perkins, L. J.; Lafortune, K.; Bailey, D.; Lambert, M.; MacKinnon, A.; Blackfield, D.; Comley, A.; Schurtz, G.; Ribeyre, X.; Lebel, E.; Casner, A.; Craxton, R. S.; Betti, R.; McKenty, P.; Anderson, K.; Theobald, W.; Schmitt, A.; Atzeni, S.; Schiavi, A.

2010-11-01

Shock ignition offers the possibility for a near-term test of high-gain ICF on the NIF at less than 1MJ drive energy and with day-1 laser hardware. We will summarize the status of target performance simulations, delineate the critical issues and describe the R&D program to be performed in order to test the potential of a shock-ignited target on NIF. In shock ignition, compressed fuel is separately ignited by a late-time laser-driven shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, simulations indicate that fusion energy gains of 60 may be achievable at laser energies around 0.5MJ. Like fast ignition, shock ignition offers high gain but requires only a single laser with less demanding timing and focusing requirements. Conventional symmetry and stability constraints apply, thus a key immediate step towards attempting shock ignition on NIF is to demonstrate adequacy of low-mode uniformity and shock symmetry under polar drive

Surface instabilities in shock loaded granular media

Science.gov (United States)

Kandan, K.; Khaderi, S. N.; Wadley, H. N. G.; Deshpande, V. S.

2017-12-01

The initiation and growth of instabilities in granular materials loaded by air shock waves are investigated via shock-tube experiments and numerical calculations. Three types of granular media, dry sand, water-saturated sand and a granular solid comprising PTFE spheres were experimentally investigated by air shock loading slugs of these materials in a transparent shock tube. Under all shock pressures considered here, the free-standing dry sand slugs remained stable while the shock loaded surface of the water-saturated sand slug became unstable resulting in mixing of the shocked air and the granular material. By contrast, the PTFE slugs were stable at low pressures but displayed instabilities similar to the water-saturated sand slugs at higher shock pressures. The distal surfaces of the slugs remained stable under all conditions considered here. Eulerian fluid/solid interaction calculations, with the granular material modelled as a Drucker-Prager solid, reproduced the onset of the instabilities as seen in the experiments to a high level of accuracy. These calculations showed that the shock pressures to initiate instabilities increased with increasing material friction and decreasing yield strain. Moreover, the high Atwood number for this problem implied that fluid/solid interaction effects were small, and the initiation of the instability is adequately captured by directly applying a pressure on the slug surface. Lagrangian calculations with the directly applied pressures demonstrated that the instability was caused by spatial pressure gradients created by initial surface perturbations. Surface instabilities are also shown to exist in shock loaded rear-supported granular slugs: these experiments and calculations are used to infer the velocity that free-standing slugs need to acquire to initiate instabilities on their front surfaces. The results presented here, while in an idealised one-dimensional setting, provide physical understanding of the conditions required to

The Numerical Simulation of the Shock Wave of Coal Gas Explosions in Gas Pipe*

Science.gov (United States)

Chen, Zhenxing; Hou, Kepeng; Chen, Longwei

2018-03-01

For the problem of large deformation and vortex, the method of Euler and Lagrange has both advantage and disadvantage. In this paper we adopt special fuzzy interface method(volume of fluid). Gas satisfies the conditions of conservation equations of mass, momentum, and energy. Based on explosion and three-dimension fluid dynamics theory, using unsteady, compressible, inviscid hydrodynamic equations and state equations, this paper considers pressure gradient’s effects to velocity, mass and energy in Lagrange steps by the finite difference method. To minimize transport errors of material, energy and volume in Finite Difference mesh, it also considers material transport in Euler steps. Programmed with Fortran PowerStation 4.0 and visualized with the software designed independently, we design the numerical simulation of gas explosion with specific pipeline structure, check the key points of the pressure change in the flow field, reproduce the gas explosion in pipeline of shock wave propagation, from the initial development, flame and accelerate the process of shock wave. This offers beneficial reference and experience to coal gas explosion accidents or safety precautions.

Physics of laser-plasma interaction for shock ignition of fusion reactions

International Nuclear Information System (INIS)

Tikhonchuk, V T; Colaïtis, A; Vallet, A; Llor Aisa, E; Duchateau, G; Nicolaï, Ph; Ribeyre, X

2016-01-01

The shock ignition scheme is an alternative approach, which aims to achieve ignition of fusion reactions in two subsequent steps: first, the target is compressed at a low implosion velocity and second, a strong converging shock is launched during the stagnation phase and ignites the hot spot. In this paper we describe the major elements of this scheme and recent achievements concerning the laser-plasma interaction, the crucial role of hot electrons in the shock generation, the shock amplification in the imploding shell and the ignition conditions. (paper)

Data derived from constitutive laws for description of shock wave propagation in concrete. Final report

International Nuclear Information System (INIS)

Eibl, J.; Ockert, J.

1994-01-01

Especially the need to design safe reactor containments, but also the necessity to protect facilities and human beings against impacts induced secondarily by explosions and detonations, demand simulations and design calculations of concrete under shock wave loading. The necessary computer codes are available, but the relevant constitutive laws for concrete with volumetric pressures up to more than 10000 MPa are lacking. Therefore shock wave tests have been carried out to develop such constitutive laws by loading concrete slabs with contact explosions. By the use of hot-molded carbon composition resistors shock waves propagating through the slab were measured. Pressures up to 13900 MPa were registered. Additionally shock wave velocities were determined from the different arrival times of the wave at the gages. By these two measured values and the conservation equations of mass and momentum the needed p-V relationship, the so called Hugoniot-Curve, was established up to 13900 MPa. Using the theory of Mie-Grueneisen and the so called P-α model the Hugoniot-Curve was extended to the equation of state for concrete. In a first step the deviatoric part of the constitutive law was attached from own static experiments considering the existing knowledge of strain rate effects since relevant dynamic tests under extreme loads are not available. With this constitutive law the analysis of the experiments then was backward verified in detail. (orig.) [de

PARTICLE ACCELERATION AT THE HELIOSPHERIC TERMINATION SHOCK WITH A STOCHASTIC SHOCK OBLIQUITY APPROACH

International Nuclear Information System (INIS)

Arthur, Aaron D.; Le Roux, Jakobus A.

2013-01-01

Observations by the plasma and magnetic field instruments on board the Voyager 2 spacecraft suggest that the termination shock is weak with a compression ratio of ∼2. However, this is contrary to the observations of accelerated particle spectra at the termination shock, where standard diffusive shock acceleration theory predicts a compression ratio closer to ∼2.9. Using our focused transport model, we investigate pickup proton acceleration at a stationary spherical termination shock with a moderately strong compression ratio of 2.8 to include both the subshock and precursor. We show that for the particle energies observed by the Voyager 2 Low Energy Charged Particle (LECP) instrument, pickup protons will have effective length scales of diffusion that are larger than the combined subshock and precursor termination shock structure observed. As a result, the particles will experience a total effective termination shock compression ratio that is larger than values inferred by the plasma and magnetic field instruments for the subshock and similar to the value predicted by diffusive shock acceleration theory. Furthermore, using a stochastically varying magnetic field angle, we are able to qualitatively reproduce the multiple power-law structure observed for the LECP spectra downstream of the termination shock

INTERFERENCE OF COUNTERPROPAGATING SHOCK WAVES

Directory of Open Access Journals (Sweden)

P. V. Bulat

2015-03-01

Full Text Available The subject of study. We examined the interaction of counterpropagating shock waves. The necessity of counterpropagating shock waves studying occurs at designing of high Mach number modern internal compression air intakes, Ramjets with subsonic and supersonic combustion, in asymmetrical supersonic nozzles and in some other cases. In a sense, this problem is a generalization of the case of an oblique shock reflection from the wall or from the plane of symmetry. With the renewed vigor, the interest to this problem emerged at the end of the 90s. This was due to the start of the programs for flight study at hypersonic speeds. The first experiments performed with air intakes, which realized the interaction of counterpropagating shock waves have shown that the change in flow velocity is accompanied by abrupt alteration of shock-wave structure, the occurrence of nonstationary and oscillatory phenomena. With an increase of flow velocity these phenomena undesirable for aircraft structure became more marked. The reason is that there are two fundamentally different modes of interaction of counterpropagating shock waves: a four-wave regular and a five-wave irregular. The transition from one mode to another can be nonstationary abrupt or gradual, it can also be accompanied by hysteresis. Main results. Criteria for the transition from regular reflection of counterpropagating shock waves to irregular are described: the criterion of von Neumann and the stationary Mach configuration criterion. We described areas in which the transition from one reflection type to another is possible only in abrupt way, as well as areas of possible gradual transition. Intensity dependences of the reflected shock waves from the intensity of interacting counterpropagating shocks were given. Qualitative pictures of shock-wave structures arising from the interaction of counterpropagating shock waves were shown. Calculation results of the intensity of outgoing gas

Diaphragmless shock wave generators for industrial applications of shock waves

Science.gov (United States)

Hariharan, M. S.; Janardhanraj, S.; Saravanan, S.; Jagadeesh, G.

2011-06-01

The prime focus of this study is to design a 50 mm internal diameter diaphragmless shock tube that can be used in an industrial facility for repeated loading of shock waves. The instantaneous rise in pressure and temperature of a medium can be used in a variety of industrial applications. We designed, fabricated and tested three different shock wave generators of which one system employs a highly elastic rubber membrane and the other systems use a fast acting pneumatic valve instead of conventional metal diaphragms. The valve opening speed is obtained with the help of a high speed camera. For shock generation systems with a pneumatic cylinder, it ranges from 0.325 to 1.15 m/s while it is around 8.3 m/s for the rubber membrane. Experiments are conducted using the three diaphragmless systems and the results obtained are analyzed carefully to obtain a relation between the opening speed of the valve and the amount of gas that is actually utilized in the generation of the shock wave for each system. The rubber membrane is not suitable for industrial applications because it needs to be replaced regularly and cannot withstand high driver pressures. The maximum shock Mach number obtained using the new diaphragmless system that uses the pneumatic valve is 2.125 ± 0.2%. This system shows much promise for automation in an industrial environment.

High-speed imaging of inhomogeneous ignition in a shock tube

Science.gov (United States)

Tulgestke, A. M.; Johnson, S. E.; Davidson, D. F.; Hanson, R. K.

2018-05-01

Homogeneous and inhomogeneous ignition of real and surrogate fuels were imaged in two Stanford shock tubes, revealing the influence of small particle fragmentation. n-Heptane, iso-octane, and Jet A were studied, each mixed in an oxidizer containing 21% oxygen and ignited at low temperatures (900-1000 K), low pressures (1-2 atm), with an equivalence ratio of 0.5. Visible images (350-1050 nm) were captured through the shock tube endwall using a high-speed camera. Particles were found to arrive near the endwalls of the shock tubes approximately 5 ms after reflection of the incident shock wave. Reflected shock wave experiments using diaphragm materials of Lexan and steel were investigated. Particles collected from the shock tubes after each experiment were found to match the material of the diaphragm burst during the experiment. Following each experiment, the shock tubes were cleaned by scrubbing with cotton cloths soaked with acetone. Particles were observed to fragment after arrival near the endwall, often leading to inhomogeneous ignition of the fuel. Distinctly more particles were observed during experiments using steel diaphragms. In experiments exhibiting inhomogeneous ignition, flames were observed to grow radially until all the fuel within the cross section of the shock tube had been consumed. The influence of diluent gas (argon or helium) was also investigated. The use of He diluent gas was found to suppress the number of particles capable of causing inhomogeneous flames. The use of He thus allowed time history studies of ignition to extend past the test times that would have been limited by inhomogeneous ignition.

Shock-wave structure formation in a dusty plasma

International Nuclear Information System (INIS)

Popel', S.I.; Golub', A.P.; Loseva, T.V.; Bingkhem, R.; Benkadda, S.

2001-01-01

Nonstationary problem on evolution perturbation and its transformation into nonlinear wave structure is considered. The method developed permits finding solution to the system of nonlinear evolution equations describing dust particles with variable charge, Boltzmann electron and inertia ions. An accurate stationary solution as ion-sonic wave structures explained by anomalous dissipation due to electric discharge of dust particles was found. Evolution of two types of initial perturbations was studied, i.e.: soliton and immobile region with increased density of ions - a step. Soliton evolution in plasma with variable charge of dust particles results in the appearance on nonstationary shock-wave structure, whereas the step evolution gives rise to appearance of a shock wave similar to the stationary one along with rarefaction wave [ru

Photon Production through Multi-step Processes Important in Nuclear Fluorescence Experiments

International Nuclear Information System (INIS)

Hagmann, C; Pruet, J

2006-01-01

The authors present calculations describing the production of photons through multi-step processes occurring when a beam of gamma rays interacts with a macroscopic material. These processes involve the creation of energetic electrons through Compton scattering, photo-absorption and pair production, the subsequent scattering of these electrons, and the creation of energetic photons occurring as these electrons are slowed through Bremsstrahlung emission. Unlike single Compton collisions, during which an energetic photon that is scattered through a large angle loses most of its energy, these multi-step processes result in a sizable flux of energetic photons traveling at large angles relative to an incident photon beam. These multi-step processes are also a key background in experiments that measure nuclear resonance fluorescence by shining photons on a thin foil and observing the spectrum of back-scattered photons. Effective cross sections describing the production of backscattered photons are presented in a tabular form that allows simple estimates of backgrounds expected in a variety of experiments. Incident photons with energies between 0.5 MeV and 8 MeV are considered. These calculations of effective cross sections may be useful for those designing NRF experiments or systems that detect specific isotopes in well-shielded environments through observation of resonance fluorescence

Modelling of thermal shock experiments of carbon based materials in JUDITH

Science.gov (United States)

Ogorodnikova, O. V.; Pestchanyi, S.; Koza, Y.; Linke, J.

2005-03-01

The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments.

Modelling of thermal shock experiments of carbon based materials in JUDITH

International Nuclear Information System (INIS)

Ogorodnikova, O.V.; Pestchanyi, S.; Koza, Y.; Linke, J.

2005-01-01

The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments

Modelling of thermal shock experiments of carbon based materials in JUDITH

Energy Technology Data Exchange (ETDEWEB)

Ogorodnikova, O.V. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany)]. E-mail: o.ogorodnikova@fz-juelich.de; Pestchanyi, S. [Forschungszentrum Karlsruhe, EURATOM-Associaton, IHM, 76021 Karlsruhe (Germany); Koza, Y. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany); Linke, J. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany)

2005-03-01

The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments.

"Driverless" Shocks in the Interplanetary Medium

Science.gov (United States)

Gopalswamy, N.; Kaiser, M. L.; Lara, A.

1999-01-01

Many interplanetary shocks have been detected without an obvious driver behind them. These shocks have been thought to be either blast waves from solar flares or shocks due to sudden increase in solar wind speed caused by interactions between large scale open and closed field lines of the Sun. We investigated this problem using a set of interplanetary shock detected {\\it in situ} by the Wind space craft and tracing their solar origins using low frequency radio data obtained by the Wind/WAVES experiment. For each of these "driverless shocks" we could find a unique coronal mass ejections (CME) event observed by the SOHO (Solar and Heliospheric Observatory) coronagraphs. We also found that these CMEs were ejected at large angles from the Sun-Earth line. It appears that the "driverless shocks" are actually driver shocks, but the drivers were not intercepted by the spacecraft. We conclude that the interplanetary shocks are much more extended than the driving CMEs.

Shock Deformation and Volcanism across the Cretaceous - Transition.

Science.gov (United States)

Huffman, Alan Royce

1990-01-01

The cause of the Cretaceous-Tertiary (K/T) transition remains one of the most controversial scientific topics in the geosciences. Geological and geophysical evidence associated with the K/T boundary have been used to argue that the extinctions were caused by meteor impact or volcanism. The goal of this study was to assess the viability of a volcanic model for the K/T transition. Comparison of natural and experimentally-shocked quartz and feldspar using optical and transmission electron microscopy (TEM) revealed that the optical and statistical character of shock-induced microstructures in volcanic rocks are different from both classic impact microstructures, and from the Raton K/T samples. A series of 31 high-explosive (HE) shock-recovery experiments at pressures to 25 GPa and temperatures to 750^circC were completed on samples of granite and quartzite. TEM and optical microscopy reveal that pre-shock temperature and pulse duration have a first-order effect on the development of shock-induced microstructures in quartz and feldspar. Application of the experimental results to natural shock-induced microstructures indicates that the volcanic microstructures are probably produced at elevated temperatures and shock pressures that do not exceed 15 GPa. The results also suggest that the Raton K/T deposits were produced at pressures below about 25 GPa. Analysis of samples from the K/T transition at DSDP Site 527 and correlations between biostratigraphy, isotopes, and the data from this study suggest that the decline in marine productivity over an extended period of time may be due to climate changes induced by basaltic volcanism. The eruption of the Deccan Traps is a viable mechanism for the K/T extinctions, and the correlation of flood basalts with every major biotic crisis in the last 250 Ma supports the link between these two phenomena. Eruption of flood basalts enriched in F, Cl, CO_2 , and SO_2, could disrupt the terrestrial ecosystem, and could produce effects

Shock and vibration protection of submerged jet impingement cooling systems: Theory and experiment

International Nuclear Information System (INIS)

Haji Hosseinloo, Ashkan; Tan, Siow Pin; Yap, Fook Fah; Toh, Kok Chuan

2014-01-01

In the recent years, advances in high power density electronics and computing systems have pushed towards more advanced thermal management technologies and higher-capacity cooling systems. Among different types of cooling systems, jet impingement technology has gained attention and been widely used in different industries for its adaptability, cooling uniformity, large heat capacity, and ease of its localization. However, these cooling systems may not function properly in dynamically harsh environment inherent in many applications such as land, sea and air transportation. In this research article, a novel double-chamber jet impingement cooling system is fabricated and its performance is studied in harsh environment. Using the authors' previous studies, isolators with optimum properties are selected to ruggedize the chassis containing the cooling chamber against shock and random vibration. Experiments are conducted on both hard-mounted and isolated chassis and the cooling performance of the system is assessed using the inlet, and impingement surface temperatures of the cooling chamber. The experimental results show the isolation system prevents any failure that otherwise would occur, and also does not compromise the thermal performance of the system. - Highlights: • A novel double-chamber jet impingement cooling system was designed and fabricated. • Comprehensive set of random vibration and shock tests are conducted. • The isolation system proved to protect the cooling system properly against mechanical failure. • Cooling system performance was not significantly affected by the input random vibration and shock

The ''injection problem'' for quasiparallel shocks

International Nuclear Information System (INIS)

Zank, G. P.; Rice, W. K. M.; le Roux, J. A.; Cairns, I. H.; Webb, G. M.

2001-01-01

For a particle to be accelerated diffusively at a shock by the first-order Fermi acceleration mechanism, the particle must be sufficiently energetic that it can scatter across all the micro- and macrostructure of the shock, experiencing compression between the converging upstream and downstream states. This is the well-known ''injection problem.'' Here the interaction of ions with the ramp of a quasiparallel shock is investigated. Some ions incident on the shock experience specular reflection, caused either by the cross-shock electrostatic potential or by mirroring as the magnetic field is bent and compressed through the ramp. Scattering of reflected ions by self-generated and pre-existing turbulence in the region upstream of the shock then acts to trap backstreaming ions and return them to the ramp, where some experience further reflections. Such repeated reflections and scattering energize a subpopulation of ions up to energies sufficiently large that they can be diffusively shock accelerated. Two ion distributions are considered: pickup ions which are assumed to be described by a shell distribution, are thermal solar wind ions which may be described by a kappa distribution. Injection efficiencies are found analytically to be very high for pickup ions and much lower for thermal solar wind ions, suggesting that this injection mechanism, stochastic reflected ion or SRI acceleration, is a natural precursor for the acceleration of the anomalous cosmic ray component at a quasiparallel shock. While significantly less efficient, SRI acceleration is also viable for thermal solar wind ions described by a kappa distribution

Shock waves and shock tubes; Proceedings of the Fifteenth International Symposium, Berkeley, CA, July 28-August 2, 1985

International Nuclear Information System (INIS)

Bershader, D.; Hanson, R.

1986-01-01

A detailed survey is presented of shock tube experiments, theoretical developments, and applications being carried out worldwide. The discussions explore shock tube physics and the related chemical, physical and biological science and technology. Extensive attention is devoted to shock wave phenomena in dusty gases and other multiphase and heterogeneous systems, including chemically reactive mixtures. Consideration is given to techniques for measuring, visualizing and theoretically modeling flowfield, shock wave and rarefaction wave characteristics. Numerical modeling is explored in terms of the application of computational fluid dynamics techniques to describing flowfields in shock tubes. Shock interactions and propagation, in both solids, fluids, gases and mixed media are investigated, along with the behavior of shocks in condensed matter. Finally, chemical reactions that are initiated as the result of passage of a shock wave are discussed, together with methods of controlling the evolution of laminar separated flows at concave corners on advanced reentry vehicles

Euler-Lagrange Simulations of Shock Wave-Particle Cloud Interaction

Science.gov (United States)

Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Park, Chanyoung; Balachandar, S.

2017-11-01

Numerical experiments of shock interacting with an evolving and fixed cloud of particles are performed. In these simulations we use Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. As validation, we use Sandia Multiphase Shock Tube experiments and particle-resolved simulations. The particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In the simulations evolving the particle cloud, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. Measurements of particle dispersion are made at different initial volume fractions. A detailed analysis of the influence of initial conditions on the evolution of the particle cloudis presented. The early time behavior of the models is studied in the fixed bed simulations at varying volume fractions and shock Mach numbers.The mean gas quantities are measured in the context of 1-way and 2-way coupled simulations. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

Analytical criterion for shock ignition of fusion reaction in hot spot

OpenAIRE

Ribeyre X.; Tikhonchuk V.T.; Breil J.; Lafon M.; Vallet A.; Bel E. Le

2013-01-01

Shock ignition of DT capsules involves two major steps. First, the fuel is assembled by means of a low velocity conventional implosion. At stagnation, the central core has a temperature lower than the one needed for ignition. Then a second, strong spherical converging shock, launched from a high intensity laser spike, arrives to the core. This shock crosses the core, rebounds at the target center and increases the central pressure to the ignition conditions. In this work we consider this latt...

UV laser-driven shock-wave experiments at ultrahigh-pressures up to 5 TPa

Energy Technology Data Exchange (ETDEWEB)

Cottet, F.; Hallouin, M.; Romain, J.P. (GRECO ILM, Laboratoire d' Enegetique et Detonique, ENSMA, 86 - Poitiers (France)); Fabbro, R.; Faral, B. (GRECO ILM, Laboratoire de Physique des Milieux Ionises, Ecole Polytechnique, 91 - Palaiseau (France))

1984-11-01

Laser-driven shock pressures up to 5 TPa at 0.26 ..mu..m wavelenth have been evaluated from measurements of shock velocity through thin metallic foils (Al, Au, Cu) by streak camera records of shock luminosity at the near face of the foil.

UV laser-driven shock-wave experiments at ultrahigh-pressures up to 5 TPa

International Nuclear Information System (INIS)

Cottet, F.; Hallouin, M.; Romain, J.P.; Fabbro, R.; Faral, B.

1984-01-01

Laser-driven shock pressures up to 5 TPa at 0.26 μm wavelenth have been evaluated from measurements of shock velocity through thin metallic foils (Al, Au, Cu) by streak camera records of shock luminosity at the near face of the foil

Experiments on second-sound shock waves in superfluid helium

International Nuclear Information System (INIS)

Cummings, J.C.; Schmidt, D.W.; Wagner, W.J.

1978-01-01

The waveform and velocity of second-sound waves in superfluid helium have been studied experimentally using superconducting, thin-film probes. The second-sound waves were generated with electrical pulses through a resistive film. Variations in pulse power, pulse duration, and bath temperature were examined. As predicted theoretically, the formation of a shock was observed at the leading or trailing edge of the waves depending on bath temperature. Breakdown of the theoretical model was observed for large pulse powers. Accurate data for the acoustic second-sound speed were derived from the measurements of shock-wave velocities and are compared with previous results

Shock compression of glow discharge polymer (GDP): density functional theory (DFT) simulations and experiments on Sandia's Z machine

Science.gov (United States)

Cochrane, Kyle R.; Ao, T.; Lemke, R. W.; Hamel, S.; Schoff, M. E.; Blue, B. E.; Herrmann, M. C.; Mattsson, T. R.

2014-03-01

Glow discharge polymer (GDP) is used extensively as capsule/ablation material in inertial confinement fusion (ICF) capsules. Accurate knowledge of the equation of state (EOS) under shock and release is particularly important for high-fidelity design, analysis, and optimization of ICF experiments since the capsule material is subject to several converging shocks as well as release towards the cryogenic fuel. We performed Density Functional Theory (DFT) based quantum molecular dynamics (QMD) simulations, to gain knowledge of the behavior of GDP - for example regarding the role of chemical dissociation during shock compression, we find that the dissociation regime along the Hugoniot extends from 50 GPa to 250 GPa. The shock pressures calculated from DFT are compared experimental data taken at Sandia's Z-machine. The GDP samples were grown in a planar geometry to improve the sample quality and maintained in a nitrogen atmosphere following manufacturing, thus allowing for a direct comparison to the DFT/QMD simulations. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's NNSA under contract DE-AC04-94AL85000.

On cylindrically converging shock waves shaped by obstacles

Energy Technology Data Exchange (ETDEWEB)

Eliasson, V; Henshaw, W D; Appelo, D

2007-07-16

Motivated by recent experiments, numerical simulations were performed of cylindrically converging shock waves. The converging shocks impinged upon a set of zero to sixteen regularly space obstacles. For more than two obstacles the resulting diffracted shock fronts formed polygonal shaped patterns near the point of focus. The maximum pressure and temperature as a function of number of obstacles were studied. The self-similar behavior of cylindrical, triangular and square-shaped shocks were also investigated.

Shocked materials at the intersection of experiment and simulation

Energy Technology Data Exchange (ETDEWEB)

Lorenzana, H. E.; Belak, J. F.; Bradley, K. S.; Bringa, E. M.; Budil, K. S.; Cazamias, J. U.; El-Dasher, B.; Hawreliak, J. A.; Hessler, J.; Kadau, K.; Kalantar, D. H.; McNaney, J. M.; Milathianaki, D.; Rosolankova, K.; Swift, D. C.; Taravillo, M.; Van Buuren, T. W.; Wark, J. S.; de la Rubia, T. Diaz

2008-04-01

Understanding the dynamic lattice response of solids under the extreme conditions of pressure, temperature and strain rate is a scientific quest that spans nearly a century. Critical to developing this understanding is the ability to probe and model the spatial and temporal evolution of the material microstructure and properties at the scale of the relevant physical phenomena-nanometers to micrometers and picoseconds to nanoseconds. While experimental investigations over this range of spatial and temporal scales were unimaginable just a decade ago, new technologies and facilities currently under development and on the horizon have brought these goals within reach for the first time. The equivalent advancements in simulation capabilities now mean that we can conduct simulations and experiments at overlapping temporal and spatial scales. In this article, we describe some of our studies which exploit existing and new generation ultrabright, ultrafast x-ray sources and large scale molecular dynamics simulations to investigate the real-time physical phenomena that control the dynamic response of shocked materials.

Shocked materials at the intersection of experiment and simulation

Energy Technology Data Exchange (ETDEWEB)

Kadau, Kai [Los Alamos National Laboratory

2008-01-01

Understanding the dynamic lattice response of solids under the extreme conditions of pressure, temperature and strain rate is a scientific quest that spans nearly a century. Critical to developing this understanding is the ability to probe and model the spatial and temporal evolution of the material microstructure and properties at the scale of the relevant physical phenomena -- nanometers to micrometers and picoseconds to nanoseconds. While experimental investigations over this range of spatial and temporal scales were unimaginable just a decade ago, new technologies and facilities currently under development and on the horizon have brought these goals within reach for the first time. The equivalent advancements in simulation capabilities now mean that we can conduct simulations and experiments at overlapping temporal and spatial scales. In this article, we describe some of our studies which exploit existing and new generation ultrabright, ultrafast x-ray sources and large scale molecular dynamics simulations to investigate the real-time physical phenomena that control the dynamic response of shocked materials.

New particle accelerations by magnetized plasma shock waves

International Nuclear Information System (INIS)

Takeuchi, Satoshi

2005-01-01

Three mechanisms concerning particle accelerations are proposed to account for the high energy of cosmic rays. A model of magnetized plasma clouds is used to simulate a shock-type wave. The attainable energies of test particles colliding with the moving magnetic clouds are investigated by analytical and numerical methods for the three mechanisms. The magnetic trapping acceleration is a new type of particle trapping and acceleration in which, in principle, the test particle is accelerated indefinitely; hence, this mechanism surpasses the Fermi-type acceleration. In the single-step acceleration, the test particle obtains a significant energy gain even though it only experiences a single collision. Lastly, there is the bouncing acceleration by which the test particle is substantially accelerated due to repeated collisions

Nitro Stretch Probing of a Single Molecular Layer to Monitor Shock Compression with Picosecond Time-Resolution

Science.gov (United States)

Berg, Christopher; Lagutchev, Alexei; Fu, Yuanxi; Dlott, Dana

2011-06-01

To obtain maximum possible temporal resolution, laser-driven shock compression of a molecular monolayer was studied using vibrational spectroscopy. The stretching transitions of nitro groups bound to aromatic rings was monitored using a nonlinear coherent infrared spectroscopy termed sum-frequency generation, which produced high-quality signals from this very thin layer. To overcome the shock opacity problem, a novel polymer overcoat method allowed us to make the observation window (witness plate) a few micrometers thick. The high signal-to-noise ratios (>100:1) obtained via this spectroscopy allowed us to study detailed behavior of the shocked molecules. To help interpret these vibrational spectra, additional spectra were obtained under conditions of static pressures up to 10 GPa and static temperatures up to 1000 C. Consequently, this experiment represents a significant step in resolving molecular dynamics during shock compression and unloading with both high spatial and temporal resolution. Supported by the Stewardship Sciences Academic Alliance Program from the Carnegie-DOE Alliance Center under grant number DOE CIW 4-3253-13 and the US Air Force Office of Scientific Research under award number FAA9550-09-1-0163.

Comparison of Hydrocode Simulations with Measured Shock Wave Velocities

International Nuclear Information System (INIS)

Hixson, R. S.; Veeser, L. R.

2014-01-01

We have conducted detailed 1- and 2-dimensional hydrodynamics calculations to assess the quality of simulations commonly made to understand various shock processes in a sample and to design shock experiments. We began with relatively simple shock experiments, where we examined the effects of the equation of state and the viscoplastic strength models. Eventually we included spallation in copper and iron and a solid-solid phase transformation in iron to assess the quality of the damage and phase transformation simulations.

Creation of ultra-high-pressure shocks by the collision of laser-accelerated disks: experiment and theory

International Nuclear Information System (INIS)

Rosen, M.D.; Phillion, D.W.; Price, R.H.; Campbell, E.M.; Obenschain, S.P.; Whitlock, R.R.; McLean, E.A.; Ripin, B.H.

1983-01-01

We have used the SHIVA laser system to accelerate carbon disks to speeds in excess of 100 km/sec. The 3KJ/3 ns pulse, on a 1 mm diameter spot of a single disk produced a conventional shock of about 5 MB. The laser energy can, however, be stored in kinetic motion of this accelerated disk and delivered (reconverted to thermal energy) upon impact with another carbon disk. This collision occurs in a time much shorter than the 3 ns pulse, thus acting as a power amplifier. The shock pressures measured upon impact are estimated to be in the 20 MB range, thus demonstrating the amplification power of this colliding disk technique in creating ultra-high pressures. Theory and computer simulations of this process will be discussed, and compared with the experiment

The stepping behavior analysis of pedestrians from different age groups via a single-file experiment

Science.gov (United States)

Cao, Shuchao; Zhang, Jun; Song, Weiguo; Shi, Chang'an; Zhang, Ruifang

2018-03-01

The stepping behavior of pedestrians with different age compositions in single-file experiment is investigated in this paper. The relation between step length, step width and stepping time are analyzed by using the step measurement method based on the calculation of curvature of the trajectory. The relations of velocity-step width, velocity-step length and velocity-stepping time for different age groups are discussed and compared with previous studies. Finally effects of pedestrian gender and height on stepping laws and fundamental diagrams are analyzed. The study is helpful for understanding pedestrian dynamics of movement. Meanwhile, it offers experimental data to develop a microscopic model of pedestrian movement by considering stepping behavior.

Dynamic Compression Experiments on Hydrogen and Deuterium in the Warm Dense Liquid.

Science.gov (United States)

Desjarlais, Michael; McCoy, Chad; Cochrane, Kyle; Mattsson, Thomas; Knudson, Marcus; Redmer, Ronald

2017-06-01

Recently a shock-ramp platform has been developed on the Z Accelerator to access off-Hugoniot states in liquids. The accelerator delivers a two-step current pulse; the first accelerates the electrode to a constant velocity, which upon impact with the sample cell creates a well-defined shock, the subsequent current rise produces ramp compression from the initially shocked state producing relatively cool (1-2 kK), high pressure (>300 GPa), high compression (10 to 15-fold compression) states. This technique allows experimental access to the region of phase space where hydrogen is predicted to undergo a first-order phase transition from an insulating molecular-like to a conducting atomic-like liquid. Here we discuss the experimental platform, survey various theoretical predictions for the liquid-liquid, insulator-to-metal transition in hydrogen, and present results of experiments on both deuterium and hydrogen that clearly show an abrupt transition to a metallic state. We also present results from recent experiments at higher temperatures (3-4 kK) and compare the observations to both first-principles theory and previous step-wise loading experiments that exhibited a minimum metallic conductivity. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Pulsed Polarimetry and magnetic sensing on the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Smith, R. J.; Hutchinson, T. M.; Weber, T. E.; Taylor, S. F.; Hsu, S. C.

2014-10-01

MSX is uniquely positioned to generate the conditions for collision-less magnetized supercritical shocks with Alvenic Mach numbers (MA) of the order 10 and higher. Significant operational strides have been made in forming plasmas over wide parameter ranges: (Te + Ti) of 10-200 eV, average neof 5-60×10+21 m-3, speeds up to 150 km/s and fields up to 1T with a highest plasma flow MA of 5 to date. The MSX plasma is unique in regards to large plasma size of 10 cm and average β higher than 0.8 making the FRC and the magnetized shock structure candidates for the application of Pulsed Polarimetry, a polarization sensitive Lidar technique. The shock dynamics are presently being investigated using internal probes, interferometry and imaging. Internal probe results and an assessment of the shock parameters will dictate the use of the UW pulsed polarimeter system in which internal ne, Teand B are to be measured. Recent results will be presented. Supported by DOE Office of Fusion Energy Sciences Funding DE-FOA-0000755.

The Presence of Turbulent and Ordered Local Structure within the ICME Shock-sheath and Its Contribution to Forbush Decrease

Energy Technology Data Exchange (ETDEWEB)

Shaikh, Zubair; Bhaskar, Ankush [Indian Institute of Geomagnetism (IIG), New Panvel, Navi Mumbai-410218 (India); Raghav, Anil, E-mail: raghavanil1984@gmail.com [University Department of Physics, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai-400098 (India)

2017-08-01

The transient interplanetary disturbances evoke short-time cosmic-ray flux decrease, which is known as Forbush decrease. The traditional model and understanding of Forbush decrease suggest that the sub-structure of an interplanetary counterpart of coronal mass ejection (ICME) independently contributes to cosmic-ray flux decrease. These sub-structures, shock-sheath, and magnetic cloud (MC) manifest as classical two-step Forbush decrease. The recent work by Raghav et al. has shown multi-step decreases and recoveries within the shock-sheath. However, this cannot be explained by the ideal shock-sheath barrier model. Furthermore, they suggested that local structures within the ICME’s sub-structure (MC and shock-sheath) could explain this deviation of the FD profile from the classical FD. Therefore, the present study attempts to investigate the cause of multi-step cosmic-ray flux decrease and respective recovery within the shock-sheath in detail. A 3D-hodogram method is utilized to obtain more details regarding the local structures within the shock-sheath. This method unambiguously suggests the formation of small-scale local structures within the ICME (shock-sheath and even in MC). Moreover, the method could differentiate the turbulent and ordered interplanetary magnetic field (IMF) regions within the sub-structures of ICME. The study explicitly suggests that the turbulent and ordered IMF regions within the shock-sheath do influence cosmic-ray variations differently.

Experimental and numerical investigation of reactive shock-accelerated flows

Energy Technology Data Exchange (ETDEWEB)

Bonazza, Riccardo [Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics

2016-12-20

The main goal of this program was to establish a qualitative and quantitative connection, based on the appropriate dimensionless parameters and scaling laws, between shock-induced distortion of astrophysical plasma density clumps and their earthbound analog in a shock tube. These objectives were pursued by carrying out laboratory experiments and numerical simulations to study the evolution of two gas bubbles accelerated by planar shock waves and compare the results to available astrophysical observations. The experiments were carried out in an vertical, downward-firing shock tube, 9.2 m long, with square internal cross section (25×25 cm²). Specific goals were to quantify the effect of the shock strength (Mach number, M) and the density contrast between the bubble gas and its surroundings (usually quantified by the Atwood number, i.e. the dimensionless density difference between the two gases) upon some of the most important flow features (e.g. macroscopic properties; turbulence and mixing rates). The computational component of the work performed through this program was aimed at (a) studying the physics of multi-phase compressible flows in the context of astrophysics plasmas and (b) providing a computational connection between laboratory experiments and the astrophysical application of shock-bubble interactions. Throughout the study, we used the FLASH4.2 code to run hydrodynamical and magnetohydrodynamical simulations of shock bubble interactions on an adaptive mesh.

Experimental and numerical investigation of reactive shock-accelerated flows

International Nuclear Information System (INIS)

Bonazza, Riccardo

2016-01-01

The main goal of this program was to establish a qualitative and quantitative connection, based on the appropriate dimensionless parameters and scaling laws, between shock-induced distortion of astrophysical plasma density clumps and their earthbound analog in a shock tube. These objectives were pursued by carrying out laboratory experiments and numerical simulations to study the evolution of two gas bubbles accelerated by planar shock waves and compare the results to available astrophysical observations. The experiments were carried out in an vertical, downward-firing shock tube, 9.2 m long, with square internal cross section (25x25 cm"2). Specific goals were to quantify the effect of the shock strength (Mach number, M) and the density contrast between the bubble gas and its surroundings (usually quantified by the Atwood number, i.e. the dimensionless density difference between the two gases) upon some of the most important flow features (e.g. macroscopic properties; turbulence and mixing rates). The computational component of the work performed through this program was aimed at (a) studying the physics of multi-phase compressible flows in the context of astrophysics plasmas and (b) providing a computational connection between laboratory experiments and the astrophysical application of shock-bubble interactions. Throughout the study, we used the FLASH4.2 code to run hydrodynamical and magnetohydrodynamical simulations of shock bubble interactions on an adaptive mesh.

Shocking matter to extreme conditions

International Nuclear Information System (INIS)

Gupta, Y.M.; Sharma, S.M.

1997-01-01

A good understanding of the thermodynamic response of matter at high compression and high energy densities is important to several areas of physics. Shock-wave experiments are uniquely suited for obtaining data at extreme conditions, and a shock-compressed matter can be viewed as a condensed system with or without dissociation or as a strongly coupled plasma. This article reviews work by Da Silva et al. in which irradiances ranging from 5x10 superscript 12 to 2x10 superscript 14 W/cm 2 were used to generate 8- to 10-ns square pulses in liquid deuterium. The authors demonstrated negligible pre-heating of the sample, steady propagation of the shock wave, and direct determination of the shock wave velocity along with particle velocity and density in the shocked state. Da Silva et al. results are compared with models and other experimental information, and the usefulness of the data in other areas is assessed. 11 refs., 1 fig

Dislocation pinning effects induced by nano-precipitates during warm laser shock peening: Dislocation dynamic simulation and experiments

Science.gov (United States)

Liao, Yiliang; Ye, Chang; Gao, Huang; Kim, Bong-Joong; Suslov, Sergey; Stach, Eric A.; Cheng, Gary J.

2011-07-01

Warm laser shock peening (WLSP) is a new high strain rate surface strengthening process that has been demonstrated to significantly improve the fatigue performance of metallic components. This improvement is mainly due to the interaction of dislocations with highly dense nanoscale precipitates, which are generated by dynamic precipitation during the WLSP process. In this paper, the dislocation pinning effects induced by the nanoscale precipitates during WLSP are systematically studied. Aluminum alloy 6061 and AISI 4140 steel are selected as the materials with which to conduct WLSP experiments. Multiscale discrete dislocation dynamics (MDDD) simulation is conducted in order to investigate the interaction of dislocations and precipitates during the shock wave propagation. The evolution of dislocation structures during the shock wave propagation is studied. The dislocation structures after WLSP are characterized via transmission electron microscopy and are compared with the results of the MDDD simulation. The results show that nano-precipitates facilitate the generation of highly dense and uniformly distributed dislocation structures. The dislocation pinning effect is strongly affected by the density, size, and space distribution of nano-precipitates.

Evaluation of kriging based surrogate models constructed from mesoscale computations of shock interaction with particles

Energy Technology Data Exchange (ETDEWEB)

Sen, Oishik, E-mail: oishik-sen@uiowa.edu [Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242 (United States); Gaul, Nicholas J., E-mail: nicholas-gaul@ramdosolutions.com [RAMDO Solutions, LLC, Iowa City, IA 52240 (United States); Choi, K.K., E-mail: kyung-choi@uiowa.edu [Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242 (United States); Jacobs, Gustaaf, E-mail: gjacobs@sdsu.edu [Aerospace Engineering, San Diego State University, San Diego, CA 92115 (United States); Udaykumar, H.S., E-mail: hs-kumar@uiowa.edu [Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242 (United States)

2017-05-01

Macro-scale computations of shocked particulate flows require closure laws that model the exchange of momentum/energy between the fluid and particle phases. Closure laws are constructed in this work in the form of surrogate models derived from highly resolved mesoscale computations of shock-particle interactions. The mesoscale computations are performed to calculate the drag force on a cluster of particles for different values of Mach Number and particle volume fraction. Two Kriging-based methods, viz. the Dynamic Kriging Method (DKG) and the Modified Bayesian Kriging Method (MBKG) are evaluated for their ability to construct surrogate models with sparse data; i.e. using the least number of mesoscale simulations. It is shown that if the input data is noise-free, the DKG method converges monotonically; convergence is less robust in the presence of noise. The MBKG method converges monotonically even with noisy input data and is therefore more suitable for surrogate model construction from numerical experiments. This work is the first step towards a full multiscale modeling of interaction of shocked particle laden flows.

Entropy Generation Across Earth's Bow Shock

Science.gov (United States)

Parks, George K.; McCarthy, Michael; Fu, Suiyan; Lee E. s; Cao, Jinbin; Goldstein, Melvyn L.; Canu, Patrick; Dandouras, Iannis S.; Reme, Henri; Fazakerley, Andrew;

Ultrafast Fiber Bragg Grating Interrogation for Sensing in Detonation and Shock Wave Experiments.

Science.gov (United States)

Rodriguez, George; Gilbertson, Steve M

2017-01-27

Chirped fiber Bragg grating (CFBG) sensors coupled to high speed interrogation systems are described as robust diagnostic approaches to monitoring shock wave and detonation front propagation tracking events for use in high energy density shock physics applications. Taking advantage of the linear distributed spatial encoding of the spectral band in single-mode CFBGs, embedded fiber systems and associated photonic interrogation methodologies are shown as an effective approach to sensing shock and detonation-driven loading processes along the CFBG length. Two approaches, one that detects spectral changes in the integrated spectrum of the CFBG and another coherent pulse interrogation approach that fully resolves its spectral response, shows that 100-MHz-1-GHz interrogation rates are possible with spatial resolution along the CFBG in the 50 µm to sub-millimeter range depending on the combination of CFBG parameters (i.e., length, chirp rate, spectrum) and interrogator design specifics. Results from several dynamic tests are used to demonstrate the performance of these high speed systems for shock and detonation propagation tracking under strong and weak shock pressure loading: (1) linear detonation front tracking in the plastic bonded explosive (PBX) PBX-9501; (2) tracking of radial decaying shock with crossover to non-destructive CFBG response; (3) shock wave tracking along an aluminum cylinder wall under weak loading accompanied by dynamic strain effects in the CFBG sensor.

Hugoniot and refractive indices of bromoform under shock compression

Science.gov (United States)

Liu, Q. C.; Zeng, X. L.; Zhou, X. M.; Luo, S. N.

2018-01-01

We investigate physical properties of bromoform (liquid CHBr3) including compressibility and refractive index under dynamic extreme conditions of shock compression. Planar shock experiments are conducted along with high-speed laser interferometry. Our experiments and previous results establish a linear shock velocity-particle velocity relation for particle velocities below 1.77 km/s, as well as the Hugoniot and isentropic compression curves up to ˜21 GPa. Shock-state refractive indices of CHBr3 up to 2.3 GPa or ˜26% compression, as a function of density, can be described with a linear relation and follows the Gladstone-Dale relation. The velocity corrections for laser interferometry measurements at 1550 nm are also obtained.

Hugoniot and refractive indices of bromoform under shock compression

Directory of Open Access Journals (Sweden)

Q. C. Liu

2018-01-01

Full Text Available We investigate physical properties of bromoform (liquid CHBr3 including compressibility and refractive index under dynamic extreme conditions of shock compression. Planar shock experiments are conducted along with high-speed laser interferometry. Our experiments and previous results establish a linear shock velocity−particle velocity relation for particle velocities below 1.77 km/s, as well as the Hugoniot and isentropic compression curves up to ∼21 GPa. Shock-state refractive indices of CHBr3 up to 2.3 GPa or ∼26% compression, as a function of density, can be described with a linear relation and follows the Gladstone-Dale relation. The velocity corrections for laser interferometry measurements at 1550 nm are also obtained.

Collisions on relativistic nuclei: shock waves

International Nuclear Information System (INIS)

Gudima, K.K.; Toneev, V.D.

1976-01-01

Experiments are analysed which indicate the possible generation of shock waves in collisions of two nuclei. Another interpretation of these data is proposed and the concerned new experiments are discussed

Underwater Shock Response of Circular HSLA Steel Plates

Directory of Open Access Journals (Sweden)

R. Rajendran

2000-01-01

Full Text Available Studies on shock response of circular plates subjected to underwater explosion is of interest to ship designers. Non-contact underwater explosion experiments were carried out on air backed circular High Strength Low Alloy (HSLA steel plates of 4 mm thickness and 290 mm diameter. The experiments were carried out in two phases. In the first phase, strain gauges were fixed at intervals of 30 mm from the centre of the plate and strains were recorded for the shock intensity gradually increasing to yielding. Semi-analytical models were derived for the elastic strain prediction which showed good agreement with the experiments. Dynamic yield stress and the shock factor for yielding were established. In the second phase, individual plates were subjected to increasing shock severity until fracture and the apex bulge depth and the thickness strains were measured. Empirical models were derived to predict the plastic deformation which were validated through a fresh set of experiments. Analysis of the fractured surface by visual examination showed that there was slant fracture indicating ductile mode of failure and the same was corroborated by Scanning Electron Microscopic (SEM examination.

Fabrication and Characterization of Targets for Shock Propagation and Radiation Burnthrough Measurements on Be-0.9 AT. % Cu Alloy

International Nuclear Information System (INIS)

Nobile, A.; Dropinski, S.C.; Edwards, J.M.; Rivera, G.; Margevicius, R.W.; Sebring, R.J.; Olson, R. E.; Tanner, D.L.

2004-01-01

Beryllium-copper alloy (Be0.9%Cu) ICF capsules are being developed for the pursuit of thermonuclear ignition at the National Ignition Facility (NIF). Success of this capsule material requires that its shock propagation and radiation burnthrough characteristics be accurately understood. To this end, experiments are being conducted to measure the shock propagation and radiation burnthrough properties of Be0.9%Cu alloy. These experiments involve measurements on small Be0.9%Cu wedge, step and flat samples. Samples are mounted on 1.6-mm-diameter x 1.2-mm-length hohlraums that are illuminated by the OMEGA laser at the University of Rochester. X-rays produced by the hohlraum drive the sample. A streaked optical pyrometer detects breakout of the shock produced by the X-ray pulse. In this paper we describe synthesis of the alloy material, fabrication and characterization of samples, and assembly of the targets. Samples were produced from Be0.9%Cu alloy that was synthesized by hot isostatic pressing of Be powder and copper flake. Samples were 850 μm diameter disks with varying thickness in the case of wedge and step samples, and uniform thickness in the case of flat samples. Sample thickness varied in the range 10-90 μm. Samples were prepared by precision lathe machining and electric discharge machining. The samples were characterized by a Veeco white light interferometer and an optical thickness measurement device that simultaneously measured the upper and lower surface contours of samples using two confocal laser probes. Several campaigns with these samples have been conducted over the past two years

Creating a Positive Prior Learning Assessment (PLA Experience: A Step-by-Step Look at University PLA

Directory of Open Access Journals (Sweden)

Sara M. Leiste

2011-01-01

Full Text Available A prior learning assessment (PLA can be an intimidating process for adult learners. Capella University’s PLA team has developed best practices, resources, and tools to foster a positive experience and to remove barriers in PLA and uses three criteria to determine how to best administer the assessment. First, a PLA must be motivating, as described by the ARCS model. Second, it must enable success. Finally, it must use available resources efficiently. The tools and resources developed according to these criteria fall into two categories: staff and online resources. PLA programs can use both to ensure that all departments provide consistent communication to learners about the PLA process, which will foster a positive experience. The PLA online lab houses centralized resources and offers one-on-one interaction with a facilitator to assist learners step-by-step in the development of their petitions. Each unit contains resources, examples, and optional assignments that help learners to develop specific aspects of the petition. By following the examples and recommendations, learners are able to submit polished petitions after they complete the units. The lab facilitator supports learners throughout the units by answering questions and providing recommendations. When learners submit their petitions, the facilitator reviews it entirely and provides feedback to strengthen the final submission that goes to a faculty reviewer for an official evaluation. All of these individuals and tools work together to help create a positive experience for learners who submit a PLA petition. This article shares these resources with the goal of strengthening PLA as a field.

Production of dissociated hydrogen gas by electro-magnetically driven shock

International Nuclear Information System (INIS)

Kondo, Kotaro; Moriyama, Takao; Hasegawa, Jun; Horioka, Kazuhiko; Oguri, Yoshiyuki

2013-01-01

Evaluation of ion stopping power which has a dependence on target temperature and density is an essential issue for heavy-ion-driven high energy density experiment. We focus on experimentally unknown dissociated hydrogen atoms as target for stopping power measurement. The precise measurement of shock wave velocity is required because the dissociated gas is produced by electro-magnetically driven shock. For beam-dissociated hydrogen gas interaction experiment, shock velocity measurement using laser refraction is proposed. (author)

Shock-induced borehole waves and fracture effects

NARCIS (Netherlands)

Fan, H.; Smeulders, D.M.J.

2012-01-01

We perform wave experiments using a vertical shock tube setup. Shock waves are generated by the rupture of a thin membrane. In the test section the incident pressure waves generate borehole-guided waves along water-saturated samples. The tube is equipped with side wall gages and a mobile pressure

Pressure vessel fracture studies pertaining to a PWR LOCA-ECC thermal shock: experiments TSE-3 and TSE-4 and update of TSE-1 and TSE-2 analysis

International Nuclear Information System (INIS)

Cheverton, R.D.; Bolt, S.E.

1977-01-01

The LOCA-ECC Thermal Shock Program was established to investigate the potential for flaw propagation in pressurized-water reactor (PWR) vessels during injection of emergency core coolant following a loss-of-coolant accident. Studies thus far have included fracture mechanics analyses of typical PWRs, the design and construction of a thermal shock test facility, determination of material properties for test specimens, and four thermal shock experiments with 0.53-m-OD (21-in.) by 0.15-m-wall (6-in.) cylindrical test specimens. In the first experiment, initiation was not expected and did not occur, although there was a small amount of subcritical crack growth. In the second experiment, initiation of a semicircular flaw took place as expected; the final length along the surface was about four times the initial length, but there was no radial growth. The third and fourth experiments were similar, and the long axial flaw initiated in good agreement with predictions

Simulations of Shock Wave Interaction with a Particle Cloud

Science.gov (United States)

Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S.'Bala'

2016-11-01

Simulations of a shock wave interacting with a cloud of particles are performed in an attempt to understand similar phenomena observed in dispersal of solid particles under such extreme environment as an explosion. We conduct numerical experiments in which a particle curtain fills only 87% of the shock tube from bottom to top. As such, the particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In this study, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. In these simulations we use a Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. Measurements of particle dispersion are made at different initial volume fractions of the particle cloud. A detailed analysis of the evolution of the particle curtain with respect to the initial conditions is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

Shock interactions with heterogeneous energetic materials

Science.gov (United States)

Yarrington, Cole D.; Wixom, Ryan R.; Damm, David L.

2018-03-01

The complex physical phenomenon of shock wave interaction with material heterogeneities has significant importance and nevertheless remains little understood. In many materials, the observed macroscale response to shock loading is governed by characteristics of the microstructure. Yet, the majority of computational studies aimed at predicting phenomena affected by these processes, such as the initiation and propagation of detonation waves in explosives or shock propagation in geological materials, employ continuum material and reactive burn model treatment. In an effort to highlight the grain-scale processes that underlie the observable effects in an energetic system, a grain-scale model for hexanitrostilbene (HNS) has been developed. The measured microstructures were used to produce synthetic computational representations of the pore structure, and a density functional theory molecular dynamics derived equation of state (EOS) was used for the fully dense HNS matrix. The explicit inclusion of the microstructure along with a fully dense EOS resulted in close agreement with historical shock compression experiments. More recent experiments on the dynamic reaction threshold were also reproduced by inclusion of a global kinetics model. The complete model was shown to reproduce accurately the expected response of this heterogeneous material to shock loading. Mesoscale simulations were shown to provide a clear insight into the nature of threshold behavior and are a way to understand complex physical phenomena.

High-Mach number, laser-driven magnetized collisionless shocks

International Nuclear Information System (INIS)

Schaeffer, Derek B.; Fox, W.; Haberberger, D.; Fiksel, G.; Bhattacharjee, A.

2017-01-01

Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and magnetized ambient plasma. Through time-resolved, 2-D imaging we observe large density and magnetic compressions that propagate at super-Alfvenic speeds and that occur over ion kinetic length scales. Electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. Furthermore, the simulations also show the shock separating from the piston, which we observe in the data at late experimental times.

Fluid dynamics of the shock wave reactor

Science.gov (United States)

Masse, Robert Kenneth

2000-10-01

High commercial incentives have driven conventional olefin production technologies to near their material limits, leaving the possibility of further efficiency improvements only in the development of entirely new techniques. One strategy known as the Shock Wave Reactor, which employs gas dynamic processes to circumvent limitations of conventional reactors, has been demonstrated effective at the University of Washington. Preheated hydrocarbon feedstock and a high enthalpy carrier gas (steam) are supersonically mixed at a temperature below that required for thermal cracking. Temperature recovery is then effected via shock recompression to initiate pyrolysis. The evolution to proof-of-concept and analysis of experiments employing ethane and propane feedstocks are presented. The Shock Wave Reactor's high enthalpy steam and ethane flows severely limit diagnostic capability in the proof-of-concept experiment. Thus, a preliminary blow down supersonic air tunnel of similar geometry has been constructed to investigate recompression stability and (especially) rapid supersonic mixing necessary for successful operation of the Shock Wave Reactor. The mixing capabilities of blade nozzle arrays are therefore studied in the air experiment and compared with analytical models. Mixing is visualized through Schlieren imaging and direct photography of condensation in carbon dioxide injection, and interpretation of visual data is supported by pressure measurement and flow sampling. The influence of convective Mach number is addressed. Additionally, thermal behavior of a blade nozzle array is analyzed for comparison to data obtained in the course of succeeding proof-of-concept experiments. Proof-of-concept is naturally succeeded by interest in industrial adaptation of the Shock Wave Reactor, particularly with regard to issues involving the scaling and refinement of the shock recompression. Hence, an additional, variable geometry air tunnel has been constructed to study the parameter

The Effect of Shock Stress and Field Strength on Shock-Induced Depoling of Normally Poled PZT 95/5

International Nuclear Information System (INIS)

CHHABILDAS, LALIT C.; FURNISH, MICHAEL D.; MONTGOMERY, STEPHEN T.; SETCHELL, ROBERT E.

1999-01-01

Shock-induced depoling of the ferroelectric ceramic PZT 95/5 is utilized in a number of pulsed power devices. Several experimental and theoretical efforts are in progress in order to improve numerical simulations of these devices. In this study we have examined the shock response of normally poled PZT 95/5 under uniaxial strain conditions. On each experiment the current produced in an external circuit and the transmitted waveform at a window interface were recorded. The peak electrical field generated within the PZT sample was varied through the choice of external circuit resistance. Shock pressures were varied from 0.6 to 4.6 GPa, and peak electrical fields were varied from 0.2 to 37 kV/cm. For a 2.4 GPa shock and the lowest peak field, a nearly constant current governed simply by the remanent polarization and the shock velocity was recorded. Both decreasing the shock pressure and increasing the electrical field resulted in reduced current generation, indicating a retardation of the depoling kinetics

Some recent advances of shock wave physics research at the Laboratory for Shock Wave and Detonation Physics Research

CERN Document Server

Jing Fu Qian

2002-01-01

Progress made in recent years on three topics that have been investigated at the Laboratory for Shock Wave and Detonation Physics Research are presented in this report. (1) A new equation of state (EOS) has been derived which can be used from a standard state to predict state variable change along an isobaric path. Good agreements between calculations for some representative metals using this new EOS and experiments have been found, covering a wide range from hundreds of MPa to hundreds of GPa and from ambient temperature to tens of thousands of GPa. (2) An empirical relation of Y/G = constant (Y is yield strength, G is shear modulus) at HT-HP has been reinvestigated and confirmed by shock wave experiment. 93W alloy was chosen as a model material. The advantage of this relation is that it is beneficial to formulate a kind of simplified constitutive equation for metallic solids under shock loading, and thus to faithfully describe the behaviours of shocked solids through hydrodynamic simulations. (3) An attempt...

Dislocation evolution and properties enhancement of GH2036 by laser shock processing: Dislocation dynamics simulation and experiment

Energy Technology Data Exchange (ETDEWEB)

Ren, X.D., E-mail: renxd@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Zhou, W.F.; Ren, Y.P.; Xu, S.D.; Liu, F.F. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yuan, S.Q. [Research Center of Fluid Machinery Engineering and Technical, Jiangsu University, Zhenjiang 212013 (China); Ren, N.F.; Huang, J.J. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)

2016-01-27

This paper systematically investigated the effect of laser shock processing (LSP) on dislocation evolution and microstructure configuration of GH2036 alloy. Surface topography and roughness were tested by Axio CSM 700 microscope. The dislocation configurations were characterized by transmission electron microscope (TEM) and simulated by multi-scale discrete dislocation dynamics (DD) method. The results have confirmed that LSP had a beneficial effect on micro-hardness, which could be increased by 16%, and the surface topography exhibited excellent stability even after thermal cycle. The dislocation density and stress–strain response have strong dependence on laser power intensity. Reasonable agreement between DD simulation and experiments is achieved. The results showed that complex random microstructures can be observed in the shocked surface. The grain refinement mechanism of LSP GH2036 involves dislocation segmentation and twin intersections.

Shock compression of simulated adobe

Science.gov (United States)

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

2017-01-01

A series of plate impact experiments were conducted to investigate the shock response of a simulant for adobe, a traditional form of building material widely used around the world. Air dried bricks were sourced from the London brick company, dry machined and impacted at a range of velocities in a single stage gas gun. The shock Hugoniot was determined (Us =2.26up+0.37) as well as release information. The material was found to behave in a manner which was similar to that of loose sand and considerably less stiff than a weak porous sandstone. The effect of any cementing of the grains was examined by shocking powdered samples contained within a cell arrangement.

Assessing Mongolian gerbil emotional behavior: effects of two shock intensities and response-independent shocks during an extended inhibitory-avoidance task

OpenAIRE

Camilo Hurtado-Parrado; Camilo González-León; Mónica A. Arias-Higuera; Angelo Cardona; Lucia G. Medina; Laura García-Muñoz; Christian Sánchez; Julián Cifuentes; Juan Carlos Forigua; Andrea Ortiz; Cesar A. Acevedo-Triana; Javier L. Rico

2017-01-01

Despite step-down inhibitory avoidance procedures that have been widely implemented in rats and mice to study learning and emotion phenomena, performance of other species in these tasks has received less attention. The case of the Mongolian gerbil is of relevance considering the discrepancies in the parameters of the step-down protocols implemented, especially the wide range of foot-shock intensities (i.e., 0.4–4.0 mA), and the lack of information on long-term performance, extinction effects,...

Analytical solutions of hypersonic type IV shock - shock interactions

Science.gov (United States)

Frame, Michael John

An analytical model has been developed to predict the effects of a type IV shock interaction at high Mach numbers. This interaction occurs when an impinging oblique shock wave intersects the most normal portion of a detached bow shock. The flowfield which develops is complicated and contains an embedded jet of supersonic flow, which may be unsteady. The jet impinges on the blunt body surface causing very high pressure and heating loads. Understanding this type of interaction is vital to the designers of cowl lips and leading edges on air- breathing hypersonic vehicles. This analytical model represents the first known attempt at predicting the geometry of the interaction explicitly, without knowing beforehand the jet dimensions, including the length of the transmitted shock where the jet originates. The model uses a hyperbolic equation for the bow shock and by matching mass continuity, flow directions and pressure throughout the flowfield, a prediction of the interaction geometry can be derived. The model has been shown to agree well with the flowfield patterns and properties of experiments and CFD, but the prediction for where the peak pressure is located, and its value, can be significantly in error due to a lack of sophistication in the model of the jet fluid stagnation region. Therefore it is recommended that this region of the flowfield be modeled in more detail and more accurate experimental and CFD measurements be used for validation. However, the analytical model has been shown to be a fast and economic prediction tool, suitable for preliminary design, or for understanding the interactions effects, including the basic physics of the interaction, such as the jet unsteadiness. The model has been used to examine a wide parametric space of possible interactions, including different Mach number, impinging shock strength and location, and cylinder radius. It has also been used to examine the interaction on power-law shaped blunt bodies, a possible candidate for

Thermal shock behaviour of SiC-fibre-reinforced glasses

International Nuclear Information System (INIS)

Klug, T.; Reichert, J.; Brueckner, R.

1992-01-01

The preparation of two SiC-fibre-reinforced glasses with very different thermal expansion coefficients and glass transition temperatures is described and the influence of long-time temperature and thermal shock behaviour of these composites on the mechanical properties is investigated by means of bending test experiments before and after thermal treatments. It will be shown from experiments and calculations on stresses due to thermal expansion mismatch between fibre and glass matrix that not only best mechanical properties but also best thermal shock behaviour are connected with low tensile intrinsic stresses produced by thermal expansion mismatch during preparation. The thermal shock resistance of the best composite (SiC fibre/DURAN glass) does not show a significant decrease of flexural strength even after 60 shocks from 550 to 25deg C in water, while the bulk glass sample of the same dimension was destroyed by one thermal shock from 350deg C. (orig.) [de

Source term experiments project (STEP): aerosol characterization system

International Nuclear Information System (INIS)

Schlenger, B.J.; Dunn, P.F.

1985-01-01

A series of four experiments has been conducted at Argonne National Laboratory's TREAT Reactor. These experiments, which are sponsored by an international consortium organized by the Electric Power Research Institute, are designed to investigate the source term, i.e., the type, quantity and timing of release of radioactive fission products from a light water reactor to the environment in the event of a severe accident in which the core is insufficiently cooled. The STEP tests have been designed to provide some of the necessary data regarding the magnitude and release rates of volatile fission products from degraded fuel pins, their physical and chemical characteristics, and aerosol formation and transport phenomena of those fission products that condense to form particles in the cooler regions of the reactor beyond the core. These are inpile experiments, whereby the test fuels are heated in a nuclear test reactor by neutron induced fission and subsequent cladding oxidation in steam environments that simulate as closely as practical predicted severe reactor accident conditions. The test sequences cover a range of pressure and fuel heatup rate, and include the effect of Ag/In/Cd control rod material. 1 ref., 8 figs., 1 tab

Time-resolved characterization and energy balance analysis of implosion core in shock-ignition experiments at OMEGA

International Nuclear Information System (INIS)

Florido, R.; Mancini, R. C.; Nagayama, T.; Tommasini, R.; Delettrez, J. A.; Regan, S. P.

2014-01-01

Time-resolved temperature and density conditions in the core of shock-ignition implosions have been determined for the first time. The diagnostic method relies on the observation, with a streaked crystal spectrometer, of the signature of an Ar tracer added to the deuterium gas fill. The data analysis confirms the importance of the shell attenuation effect previously noted on time-integrated spectroscopic measurements of thick-wall targets [R. Florido et al., Phys. Rev. E 83, 066408 (2011)]. This effect must be taken into account in order to obtain reliable results. The extracted temperature and density time-histories are representative of the state of the core during the implosion deceleration and burning phases. As a consequence of the ignitor shock launched by the sharp intensity spike at the end of the laser pulse, observed average core electron temperature and mass density reach T ∼ 1100 eV and ρ ∼ 2 g/cm 3 ; then temperature drops to T ∼ 920 eV while density rises to ρ ∼ 3.4 g/cm 3 about the time of peak compression. Compared to 1D hydrodynamic simulations, the experiment shows similar maximum temperatures and smaller densities. Simulations do not reproduce all observations. Differences are noted in the heating dynamics driven by the ignitor shock and the optical depth time-history of the compressed shell. Time-histories of core conditions extracted from spectroscopy show that the implosion can be interpreted as a two-stage polytropic process. Furthermore, an energy balance analysis of implosion core suggests an increase in total energy greater than what 1D hydrodynamic simulations predict. This new methodology can be implemented in other ICF experiments to look into implosion dynamics and help to understand the underlying physics

Time-resolved characterization and energy balance analysis of implosion core in shock-ignition experiments at OMEGA

Energy Technology Data Exchange (ETDEWEB)

Florido, R., E-mail: ricardo.florido@ulpgc.es; Mancini, R. C.; Nagayama, T. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States); Tommasini, R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Delettrez, J. A.; Regan, S. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2014-10-15

Time-resolved temperature and density conditions in the core of shock-ignition implosions have been determined for the first time. The diagnostic method relies on the observation, with a streaked crystal spectrometer, of the signature of an Ar tracer added to the deuterium gas fill. The data analysis confirms the importance of the shell attenuation effect previously noted on time-integrated spectroscopic measurements of thick-wall targets [R. Florido et al., Phys. Rev. E 83, 066408 (2011)]. This effect must be taken into account in order to obtain reliable results. The extracted temperature and density time-histories are representative of the state of the core during the implosion deceleration and burning phases. As a consequence of the ignitor shock launched by the sharp intensity spike at the end of the laser pulse, observed average core electron temperature and mass density reach T ∼ 1100 eV and ρ ∼ 2 g/cm{sup 3}; then temperature drops to T ∼ 920 eV while density rises to ρ ∼ 3.4 g/cm{sup 3} about the time of peak compression. Compared to 1D hydrodynamic simulations, the experiment shows similar maximum temperatures and smaller densities. Simulations do not reproduce all observations. Differences are noted in the heating dynamics driven by the ignitor shock and the optical depth time-history of the compressed shell. Time-histories of core conditions extracted from spectroscopy show that the implosion can be interpreted as a two-stage polytropic process. Furthermore, an energy balance analysis of implosion core suggests an increase in total energy greater than what 1D hydrodynamic simulations predict. This new methodology can be implemented in other ICF experiments to look into implosion dynamics and help to understand the underlying physics.

Defining Moments in MMWR History: Toxic-Shock Syndrome -- 1980

Centers for Disease Control (CDC) Podcasts

In the late 1970s and early 1980s, an outbreak of a disease called Toxic Shock Syndrome made healthy women sick. CDC's disease detectives helped unravel the link between Toxic Shock Syndrome and high-absorbency tampons. MMWR was the first scientific publication to break the news of these cases. In this podcast, Dr. Kathy Shands, former chief of CDC's Toxic Shock Syndrome Task Force, recalls her experience working with state epidemiologists to identify the link between toxic shock syndrome and tampon use.

Numerical simulation of the structure of collisionless supercritical shocks

International Nuclear Information System (INIS)

Lipatov, A.S.

1990-01-01

Research on the structure of a collisionless shock wave and on acceleration of charged particles is important for analyzing the processes accompanying solar flares, and also for studying the shock waves which are excited in the interaction of the solar wind with planets, comets and interstellar gas, the mechanisms for the acceleration of cosmic rays, the processes accompanying magnetic field reconnection, explosion of Supernova. The study of the shock is also important for studying the processes in the active experiments in space. In the present report only supercritical shocks are considered, when partial ion reflection plays a controlling roll in shock formation. One- and two-dimensional simulations of the perpendicular shocks are presented. (R.P.) 33 refs.; 4 figs

Linear step drive

International Nuclear Information System (INIS)

Haniger, L.; Elger, R.; Kocandrle, L.; Zdebor, J.

1986-01-01

A linear step drive is described developed in Czechoslovak-Soviet cooperation and intended for driving WWER-1000 control rods. The functional principle is explained of the motor and the mechanical and electrical parts of the drive, power control, and the indicator of position are described. The motor has latches situated in the reactor at a distance of 3 m from magnetic armatures, it has a low structural height above the reactor cover, which suggests its suitability for seismic localities. Its magnetic circuits use counterpoles; the mechanical shocks at the completion of each step are damped using special design features. The position indicator is of a special design and evaluates motor position within ±1% of total travel. A drive diagram and the flow chart of both the control electronics and the position indicator are presented. (author) 4 figs

Geometrical shock dynamics for magnetohydrodynamic fast shocks

KAUST Repository

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

2016-01-01

We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

Geometrical shock dynamics for magnetohydrodynamic fast shocks

KAUST Repository

Mostert, W.

2016-12-12

We describe a formulation of two-dimensional geometrical shock dynamics (GSD) suitable for ideal magnetohydrodynamic (MHD) fast shocks under magnetic fields of general strength and orientation. The resulting area–Mach-number–shock-angle relation is then incorporated into a numerical method using pseudospectral differentiation. The MHD-GSD model is verified by comparison with results from nonlinear finite-volume solution of the complete ideal MHD equations applied to a shock implosion flow in the presence of an oblique and spatially varying magnetic field ahead of the shock. Results from application of the MHD-GSD equations to the stability of fast MHD shocks in two dimensions are presented. It is shown that the time to formation of triple points for both perturbed MHD and gas-dynamic shocks increases as (Formula presented.), where (Formula presented.) is a measure of the initial Mach-number perturbation. Symmetry breaking in the MHD case is demonstrated. In cylindrical converging geometry, in the presence of an azimuthal field produced by a line current, the MHD shock behaves in the mean as in Pullin et al. (Phys. Fluids, vol. 26, 2014, 097103), but suffers a greater relative pressure fluctuation along the shock than the gas-dynamic shock. © 2016 Cambridge University Press

Constrained reaction volume approach for studying chemical kinetics behind reflected shock waves

KAUST Repository

Hanson, Ronald K.; Pang, Genny A.; Chakraborty, Sreyashi; Ren, Wei; Wang, Shengkai; Davidson, David Frank

2013-01-01

We report a constrained-reaction-volume strategy for conducting kinetics experiments behind reflected shock waves, achieved in the present work by staged filling in a shock tube. Using hydrogen-oxygen ignition experiments as an example, we

Thermal-shock experiments with flawed clad cylinders

International Nuclear Information System (INIS)

Cheverton, R.D.; Bryson, J.W.; Alexander, D.J.

1989-01-01

The life expectancy of LWR pressure vessels is influenced by a reduction in fracture toughness that is the result of radiation damage. As the fracture toughness decreases, the probability of propagation of preexisting flaws (sharp, crack-like defects) in the wall of the vessel increases. The probability of propagation is also influenced by the type of loading condition and the type of flaws that might exist. A loading condition of particular concern is referred to as pressurized thermal shock (PTS), and a flaw of particular concern for PTS loading conditions is a shallow surface flaw. A sudden cooling (thermal shock) of the inner surface of the vessel results in relatively high tensile stresses and relatively low fracture toughness at the inner surface. In addition, the attenuation of the fast-neutron fluence also results in relatively low fracture toughness at the inner surface. Under some circumstances, this combination of high stress and low toughness at the inner surface makes it possible for very shallow surface flaws to propagate. The PTS issue has been under investigation for quite some time, but thus far possible beneficial effects, other than thermal resistance, of the cladding on the inner surface of the vessel have not been included in the analysis of flaw behavior. This document discusses this effect of cladding on surface flaws and crack propagation

Astrophysical radiative shocks: From modeling to laboratory experiments

Czech Academy of Sciences Publication Activity Database

Gonzales, N.; Stehlé, C.; Audit, E.; Busquet, M.; Rus, Bedřich; Thais, F.; Acef, O.; Barroso, P.; Bar-Shalom, A.; Bauduin, D.; Kozlová, Michaela; Lery, T.; Madouri, A.; Mocek, Tomáš; Polan, Jiří

2006-01-01

Roč. 24, - (2006), s. 535-540 ISSN 0263-0346 EU Projects: European Commission(XE) 506350 - LASERLAB-EUROPE; European Commission(XE) 5592 - JETSET Grant - others:CNRS(FR) PNPS Institutional research plan: CEZ:AV0Z10100523 Keywords : laboratory astrophysics * laser plasmas * radiative shock waves * radiative transfer Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.958, year: 2006

Ion species stratification within strong shocks in two-ion plasmas

Science.gov (United States)

Keenan, Brett D.; Simakov, Andrei N.; Taitano, William T.; Chacón, Luis

2018-03-01

Strong collisional shocks in multi-ion plasmas are featured in many environments, with Inertial Confinement Fusion (ICF) experiments being one prominent example. Recent work [Keenan et al., Phys. Rev. E 96, 053203 (2017)] answered in detail a number of outstanding questions concerning the kinetic structure of steady-state, planar plasma shocks, e.g., the shock width scaling by the Mach number, M. However, it did not discuss shock-driven ion-species stratification (e.g., relative concentration modification and temperature separation). These are important effects since many recent ICF experiments have evaded explanation by standard, single-fluid, radiation-hydrodynamic (rad-hydro) numerical simulations, and shock-driven fuel stratification likely contributes to this discrepancy. Employing the state-of-the-art Vlasov-Fokker-Planck code, iFP, along with multi-ion hydro simulations and semi-analytics, we quantify the ion stratification by planar shocks with the arbitrary Mach number and the relative species concentration for two-ion plasmas in terms of ion mass and charge ratios. In particular, for strong shocks, we find that the structure of the ion temperature separation has a nearly universal character across ion mass and charge ratios. Additionally, we find that the shock fronts are enriched with the lighter ion species and the enrichment scales as M4 for M ≫ 1.

Elastic-plastic fracture mechanics study of thermal shock cracking

International Nuclear Information System (INIS)

Hirano, K.; Kobayashi, H.; Nakazawa, H.

1980-01-01

This paper describes thermal shock experiments conducted on a nuclear pressure vessel steel (A533 Grade B Class 1), an AISI304 steel and a tool steel (JIS SKD62) using both a new thermal shock test facility and method. Analysis of their quasi-static thermal stress intensity factors is performed on the basis of linear-elastic fracture mechanics; and a thermal shock fracture toughness value, Ksub(tsc) is evaluated. Then elastic-plastic fracture toughness tests are carried out in the same high temperature range of the thermal shock experiment, and a relation between the stretched zone width, SZW, formed as a result of the fatigue precrack tip plastic blunting and the J-integral is clarified. An elastic-plastic thermal shock fracture toughness value, Jsub(tsc), is evaluated from a critical value of the stretched zone width, SZWsub(tsc), at the initiation of the thermal shock cracking by using the relation between SZW and J. The Jsub(tsc) value is compared with an elastic-plastic fracture toughness value, Jsub(Ic), and the difference between these Jsub(tsc) and Jsub(Ic) values is discussed on the basis of fractography. (author)

Analysis of crack behavior in the JRC Ispra pressurized thermal shock experiment

International Nuclear Information System (INIS)

Jovanovic, A.; Lucia, A.C.

1990-01-01

The analytical work performed in the framework of the Pressurized Thermal Shock (PTS) experimental research at the JRC Ispra, Italy, is described in the paper. In particular, the development of the FRAP preprocessor and development and implementation of a methodology for analysis of local non-stationary heat transfer coefficients during a PTS, have been tackled. FRAP is used as a front-end for the finite element code ABAQUS, for the heat transfer, stress and fracture mechanics analyses. The ABAQUS results are used further on, for the probabilistic fatigue crack analysis performed by the JRC Ispra code COVASTOL. Only the preliminary results of application of FRAP, ABAQUS and COVASTOL codes in the experiment are given in this paper, in order to illustrate the applied analytical procedure. (orig.)

Chondrule destruction in nebular shocks

Energy Technology Data Exchange (ETDEWEB)

Jacquet, Emmanuel; Thompson, Christopher, E-mail: ejacquet@mnhn.fr [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St George Street, Toronto, ON M5S 3H8 (Canada)

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.

Numerical analysis of three-dimensional MHD shock interactions in an inhomogeneous medium

International Nuclear Information System (INIS)

Prndergast, M.; Wu, S.T.

1987-01-01

Study of the formation and propagation of solar-originated shock waves in heliospheric space has attracted significant attention in the past decade. This attention is important because the propagation of shocks in heliospheric space has been thought of as one of the major physical processes for solar wind and cosmic ray modulations and their subsequent influence on the earth's environment. A version of the two step Lax-Wendroff difference method is used to seek solutions of the unsteady magnetohydrodynamic (MHD) equations for the study of a solar flare generated shock wave propagating through an inhomogeneous medium. 8 references

Shock Prevention

Science.gov (United States)

1978-01-01

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

Experimental study of the Richtmyer-Meshkov instability induced by a Mach 3 shock wave

International Nuclear Information System (INIS)

BP Puranik; JG Oakley; MH Anderson; R Bonaazza

2003-01-01

OAK-B135 An experimental investigation of a shock-induced interfacial instability (Richtmyer-Meshkov instability) is undertaken in an effort to study temporal evolution of interfacial perturbations in the late stages of development. The experiments are performed in a vertical shock tube with a square cross-section. A membraneless interface is prepared by retracting a sinusoidally shaped metal plate initially separating carbon dioxide from air, with both gases initially at atmospheric pressure. With carbon dioxide above the plate, the Rayleigh-Taylor instability commences as the plate is retracted and the amplitude of the initial sinusoidal perturbation imposed on the interface begins to grow. The interface is accelerated by a strong shock wave (M=3.08) while its shape is still sinusoidal and before the Kelvin-Helmhotz instability distorts it into the well known mushroom-like structures; its initial amplitude to wavelength ratio is large enough that the interface evolution enters its nonlinear stage very shortly after shock acceleration. The pre-shock evolution of the interface due to the Rayleigh-Taylor instability and the post-shock evolution of the interface due to the Richtmyer-Meshkov instability are visualized using planar Mie scattering. The pre-shock evolution of the interface is carried out in an independent set of experiments. The initial conditions for the Richtmyer-Meshkov experiment are determined from the pre-shock Rayleigh-Taylor growth. One image of the post-shock interface is obtained per experiment and image sequences, showing the post-shock evolution of the interface, are constructed from several experiments. The growth rate of the perturbation amplitude is measured and compared with two recent analytical models of the Richtmyer-Meshkov instability

Shock timing measurements in DT ice layers

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R. J.; Ross, J. S.; Lepape, S.; Ralph, J. E.; Berzak Hopkins, L. F.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2013-10-01

Shock timing experiments on the National Ignition Facility (NIF) are routinely conducted using the keyhole target geometry, in which the strength and timing of multiple shocks are measured in a liquid-deuterium (D2) filled capsule interior. These targets have recently been modified to improve the surrogacy to ignition implosions by replacing the standard, continuous liquid D2 capsule fill with a deuterium-tritium (DT) ice layer with a central DT gas fill. These experiments remove any possible material surrogacy difference between D2 and DT as well as incorporating the physics of multiple shock release and recompression events from an ice layer of finite thickness, an effect that is absent in the liquid-filled targets. Experimental results and comparisons with numerical simulation are presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

Emissive spectra of shock-heated argon

International Nuclear Information System (INIS)

Tang Jingyou; Gu Yan; Peng Qixian; Bai Yulin; Li Ping

2003-01-01

To study the radiant properties of argon under weak shock compression, an aluminum target filled with gaseous argon at ambient states was impacted by a tungsten alloy projectile which was launched from a two-stage light gun to 2.00 km/s. The radiant signals of single shock-compressed argon were recorded by a six-channel pyrometer and oscilloscopes, which varied with time linearly for the five channels from 405 nm to 700 nm and exponentially for the channel 800 nm, and the corresponding velocity of shock wave was determined to be 4.10 ± 0.09 km/s. By the present experiment, it has been shown that the absorbability of the shock-heated argon is low for visual light and the optical depths of argon gas turn from thin to thick as wavelengths gradually increase. The time-resolved spectra in the rising-front of the radiant signal in the re-shocked argon were recorded by means of an OMA, and strong emissive spectrum bands near 450 nm light-wave length but no linear spectrum were found. The emissive spectrum properties of shock-compression argon were qualitatively explained by the state parameters and ionization degree

Early time implosion symmetry from two-axis shock-timing measurements on indirect drive NIF experiments

Energy Technology Data Exchange (ETDEWEB)

Moody, J. D., E-mail: moody4@llnl.gov; Robey, H. F.; Celliers, P. M.; Munro, D. H.; Barker, D. A.; Baker, K. L.; Döppner, T.; Hash, N. L.; Berzak Hopkins, L.; LaFortune, K.; Landen, O. L.; LePape, S.; MacGowan, B. J.; Ralph, J. E.; Ross, J. S.; Widmayer, C. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Nikroo, A.; Giraldez, E. [General Atomics, San Diego, California 92186-5608 (United States); Boehly, T. [Laboratory for Laser Energetics, Rochester, New York 14623-1299 (United States)

2014-09-15

An innovative technique has been developed and used to measure the shock propagation speed along two orthogonal axes in an inertial confinement fusion indirect drive implosion target. This development builds on an existing target and diagnostic platform for measuring the shock propagation along a single axis. A 0.4 mm square aluminum mirror is installed in the ablator capsule which adds a second orthogonal view of the x-ray-driven shock speeds. The new technique adds capability for symmetry control along two directions of the shocks launched in the ablator by the laser-generated hohlraum x-ray flux. Laser power adjustments in four different azimuthal cones based on the results of this measurement can reduce time-dependent symmetry swings during the implosion. Analysis of a large data set provides experimental sensitivities of the shock parameters to the overall laser delivery and in some cases shows the effects of laser asymmetries on the pole and equator shock measurements.

Planar shock focusing through perfect gas lens: First experimental demonstration

International Nuclear Information System (INIS)

Biamino, Laurent; Mariani, Christian; Jourdan, Georges; Houas, Lazhar; Vandenboomgaerde, Marc; Souffland, Denis

2014-01-01

When a shock wave crosses an interface between two materials, this interface becomes unstable and the Richtmyer-Meshkov instability develops. Such instability has been extensively studied in the planar case, and numerous results were presented during the previous workshops. But the Richtmyer-Meshkov (Richtmyer, 1960, 'Taylor Instability in Shock Acceleration of Compressible Fluids,' Commun. Pure Appl. Math., 13(2), pp. 297-319; Meshkov, 1969, 'Interface of Two Gases Accelerated by a Shock Wave,' Fluid Dyn., 4(5), pp. 101-104) instability also occurs in a spherical case where the convergence effects must be taken into account. As far as we know, no conventional (straight section) shock tube facility has been used to experimentally study the Richtmyer-Meshkov instability in spherical geometry. The idea originally proposed by Dimotakis and Samtaney (2006, 'Planar Shock Cylindrical Focusing by a Perfect-Gas Lens,' Phys. Fluid., 18(3), pp. 031705-031708) and later generalized by Vandenboomgaerde and Aymard (2011, 'Analytical Theory for Planar Shock Focusing Through Perfect Gas Lens and Shock Tube Experiment Designs,' Phys. Fluid., 23(1), pp. 016101-016113) was to retain the flexibility of a conventional shock tube to convert a planar shock wave into a cylindrical one through a perfect gas lens. This can be done when a planar shock wave passes through a shaped interface between two gases. By coupling the shape with the impedance mismatch at the interface, it is possible to generate a circular transmitted shock wave. In order to experimentally check the feasibility of this approach, we have implemented the gas lens technique on a conventional shock tube with the help of a convergent test section, an elliptic stereo lithographed grid, and a nitrocellulose membrane. First experimental sequences of Schlieren images have been obtained for an incident shock wave Mach number equal to 1.15 and an air/SF_6-shaped interface. Experimental results indicate that the shock that moves

Hydrodynamic simulations of microjetting from shock-loaded grooves

Science.gov (United States)

Roland, C.; de Rességuier, T.; Sollier, A.; Lescoute, E.; Soulard, L.; Loison, D.

2017-01-01

The interaction of a shock wave with a free surface which has geometrical defects, such as cavities or grooves, may lead to the ejection of micrometric debris at velocities of km/s. This process can be involved in many applications, like pyrotechnics or industrial safety. Recent laser shock experiments reported elsewhere in this conference have provided some insight into jet formation as well as jet tip velocities for various groove angles and shock pressures. Here, we present hydrodynamic simulations of these experiments, in both 2D and 3D geometries, using both finite element method and smoothed particle hydrodynamics. Numerical results are compared to several theoretical predictions including the Richtmyer-Meshkov instabilities. The role of the elastic-plastic behavior on jet formation is illustrated. Finally, the possibility to simulate the late stage of jet expansion and fragmentation is explored, to evaluate the mass distribution of the ejecta and their ballistic properties, still essentially unknown in the experiments.

Experiments in a Combustion-Driven Shock Tube with an Area Change

Science.gov (United States)

Schmidt, B. E.; Bobbitt, B.; Parziale, N. J.; Shepherd, J. E.

Shock tubes are versatile and useful tools for studying high temperature gas dynamics and the production of hypervelocity flows. High shock speeds are desirable for creating higher enthalpy, pressure, and temperature in the test gas which makes the study of thermo-chemical effects on fluid dynamics possible. Independent of construction and operational cost, free-piston drivers, such as the one used in the T5 facility at Caltech, give the best performance [3]. The high operational cost and long turnaround time of such a facility make a more economical option desirable for smaller-scale testing.

Physics of Collisionless Shocks Space Plasma Shock Waves

CERN Document Server

Balogh, André

2013-01-01

The present book provides a contemporary systematic treatment of shock waves in high-temperature collisionless plasmas as are encountered in near Earth space and in Astrophysics. It consists of two parts. Part I develops the complete theory of shocks in dilute hot plasmas under the assumption of absence of collisions among the charged particles when the interaction is mediated solely by the self-consistent electromagnetic fields. Such shocks are naturally magnetised implying that the magnetic field plays an important role in their evolution and dynamics. This part treats both subcritical shocks, which dissipate flow energy by generating anomalous resistance or viscosity, and supercritical shocks. The main emphasis is, however, on super-critical shocks where the anomalous dissipation is insufficient to retard the upstream flow. These shocks, depending on the direction of the upstream magnetic field, are distinguished as quasi-perpendicular and quasi-parallel shocks which exhibit different behaviours, reflecti...

Shear strength of shock-loaded polycrystalline tungsten

International Nuclear Information System (INIS)

Asay, J.R.; Chhabildas, L.C.; Dandekar, D.P.

1980-01-01

Previous experiments have suggested that tungsten undergoes a significant loss of shear strength when shock loaded to stresses greater than 7 GPa. In order to investigate this effect in more detail, a series of experiments was conducted in which polycrystalline tungsten was first shock loaded to approximately 10 GPa and then either unloaded or reloaded from the shocked state. Analysis of measured time-resolved wave profiles indicates that during initial compression to 9.7 GPa, the shear stress in polycrystalline tungsten increases to a maximum value of 1.1 GPA near a longitudinal stress of 5 GPa, but decreases to a final value of 0.8 GPa for stresses approaching 10 GPa. During reloading from a longitudinal stress of 9.7 GPa to a final value of approx.14 GPa, the shear stress increases to a peak value of 1.2 GPa and softens to 1.0 GPa in the final state. During unloading from the shocked state, the initial response is elastic with a strong Baushinger effect. Examination of a recovered sample shows evidence for both deformation slipping and twinning, which may be responsible for the observed softening

Shock Tube as an Impulsive Application Device

Directory of Open Access Journals (Sweden)

Soumya Ranjan Nanda

2017-01-01

Full Text Available Current investigations solely focus on application of an impulse facility in diverse area of high-speed aerodynamics and structural mechanics. Shock tube, the fundamental impulse facility, is specially designed and calibrated for present objectives. Force measurement experiments are performed on a hemispherical test model integrated with the stress wave force balance. Similar test model is considered for heat transfer measurements using coaxial thermocouple. Force and heat transfer experiments demonstrated that the strain gauge and thermocouple have lag time of 11.5 and 9 microseconds, respectively. Response time of these sensors in measuring the peak load is also measured successfully using shock tube facility. As an outcome, these sensors are found to be suitable for impulse testing. Lastly, the response of aluminum plates subjected to impulsive loading is analyzed by measuring the in-plane strain produced during deformation. Thus, possibility of forming tests in shock is also confirmed.

Notes on the Prediction of Shock-induced Boundary-layer Separation

Science.gov (United States)

Lange, Roy H.

1953-01-01

The present status of available information relative to the prediction of shock-induced boundary-layer separation is discussed. Experimental results showing the effects of Reynolds number and Mach number on the separation of both laminar and turbulent boundary layer are given and compared with available methods for predicting separation. The flow phenomena associated with separation caused by forward-facing steps, wedges, and incident shock waves are discussed. Applications of the flat-plate data to problems of separation on spoilers, diffusers, and scoop inlets are indicated for turbulent boundary layers.

The Effects of Prior Cold Work on the Shock Response of Copper

Science.gov (United States)

Millett, J. C. F.; Higgins, D. L.; Chapman, D. J.; Whiteman, G.; Jones, I. P.; Chiu, Y.-L.

2018-04-01

A series of experiments have been performed to probe the effects of dislocation density on the shock response of copper. The shear strength immediately behind the shock front has been measured using embedded manganin stress gauges, whilst the post shock microstructural and mechanical response has been monitored via one-dimensional recovery experiments. Material in the half hard (high dislocation density) condition was shown to have both a higher shear strength and higher rate of change of shear strength with impact stress than its annealed (low dislocation density) counterpart. Microstructural analysis showed a much higher dislocation density in the half hard material compared to the annealed after shock loading, whilst post shock mechanical examination showed a significant degree of hardening in the annealed state with reduced, but still significant amount in the half hard state, thus showing a correlation between temporally resolved stress gauge measurements and post shock microstructural and mechanical properties.

Electrostatic shock structures in dissipative multi-ion dusty plasmas

Science.gov (United States)

Elkamash, I. S.; Kourakis, I.

2018-06-01

A comprehensive analytical model is introduced for shock excitations in dusty bi-ion plasma mixtures, taking into account collisionality and kinematic (fluid) viscosity. A multicomponent plasma configuration is considered, consisting of positive ions, negative ions, electrons, and a massive charged component in the background (dust). The ionic dynamical scale is focused upon; thus, electrons are assumed to be thermalized, while the dust is stationary. A dissipative hybrid Korteweg-de Vries/Burgers equation is derived. An analytical solution is obtained, in the form of a shock structure (a step-shaped function for the electrostatic potential, or an electric field pulse) whose maximum amplitude in the far downstream region decays in time. The effect of relevant plasma configuration parameters, in addition to dissipation, is investigated. Our work extends earlier studies of ion-acoustic type shock waves in pure (two-component) bi-ion plasma mixtures.

Viscosity of aluminum under shock-loading conditions

International Nuclear Information System (INIS)

Ma Xiao-Juan; Liu Fu-Sheng; Zhang Ming-Jian; Sun Yan-Yun

2011-01-01

A reliable data treatment method is critical for viscosity measurements using the disturbance amplitude damping method of shock waves. In this paper the finite difference method is used to obtain the numerical solutions for the disturbance amplitude damping behaviour of the sinusoidal shock front in a flyer-impact experiment. The disturbance amplitude damping curves are used to depict the numerical solutions of viscous flow. By fitting the experimental data to the numerical solutions of different viscosities, we find that the effective shear viscosity coefficients of shocked aluminum at pressures of 42, 78 and 101 GPa are (1500±100) Pa·s, (2800±100) Pa·s and (3500±100) Pa·s respectively. It is clear that the shear viscosity of aluminum increases with an increase in shock pressure, so aluminum does not melt below a shock pressure of 101 GPa. This conclusion is consistent with the sound velocity measurement. (interdisciplinary physics and related areas of science and technology)

Shock wave focusing in water inside convergent structures

Directory of Open Access Journals (Sweden)

C Wang

2016-09-01

Full Text Available Experiments on shock focusing in water-filled convergent structures have been performed. A shock wave in water is generated by means of a projectile, launched from a gas gun, which impacts a water-filled convergent structure. Two types of structures have been tested; a bulk material and a thin shell structure. The geometric shape of the convergent structures is given by a logarithmic spiral, and this particular shape is chosen because it maximizes the amount of energy reaching the focal region. High-speed schlieren photography is used to visualize the shock dynamics during the focusing event. Results show that the fluid-structure interaction between the thin shell structure and the shock wave in the water is different from that of a bulk structure; multiple reflections of the shock wave inside the thin shell are reflected back into the water, thus creating a wave train, which is not observed for shock focusing in a bulk material.

Shock wave and flame front induced detonation in a rapid compression machine

Science.gov (United States)

Wang, Y.; Qi, Y.; Xiang, S.; Mével, R.; Wang, Z.

2018-05-01

The present study focuses on one mode of detonation initiation observed in a rapid compression machine (RCM). This mode is referred to as shock wave and flame front-induced detonation (SWFID). Experimental high-speed imaging and two-dimensional numerical simulations with skeletal chemistry are combined to unravel the dominant steps of detonation initiation under SWFID conditions. It is shown that the interaction between the shock wave generated by the end-gas auto-ignition and the spherical flame creates a region of high pressure and temperature which enables the acceleration of the flame front and the detonation onset. The experimental observation lacks adequate spatial and temporal resolution despite good reproducibility of the detonation onset. Based on the numerical results, phenomenological interpretation of the event within the framework of shock wave refraction indicates that the formation of a free-precursor shock wave at the transition between regular and irregular refraction may be responsible for detonation onset. The present results along with previous findings on shock wave reflection-induced detonation in the RCM indicate that super-knock occurs after the interaction of the shock wave generated by end-gas auto-ignition with the RCM walls, preignition flame, or another shock wave.

Tailored ramp-loading via shock release of stepped-density reservoirs

International Nuclear Information System (INIS)

Prisbrey, Shon T.; Park, Hye-Sook; Remington, Bruce A.; Cavallo, Robert; May, Mark; Pollaine, Stephen M.; Rudd, Robert; Maddox, Brian; Comley, Andrew; Fried, Larry; Blobaum, Kerri; Wallace, Russ; Wilson, Mike; Swift, David; Satcher, Joe; Kalantar, Dan; Perry, Ted; Giraldez, Emilio; Farrell, Michael; Nikroo, Abbas

2012-01-01

The concept of a gradient piston drive has been extended from that of a single component reservoir, such as a high explosive, to that of a multi-component reservoir that utilizes low density foams and large shocks to achieve high pressures (∼3.5 mbar) and controlled pressure vs. time profiles on a driven sample. Simulated and experimental drives shaped through the use of multiple component (including carbonized resorcinol formaldehyde and SiO 2 foam) reservoirs are compared. Individual density layers in a multiple component reservoir are shown to correlate with velocity features in the measured drive which enables the ability to tune a pressure drive by adjusting the components of the reservoir. Pre-shot simulations are shown to be in rough agreement with the data, but post-shot simulations involving the use of simulated plasma drives were needed to achieve an exact match. Results from a multiple component reservoir shot (∼3.5 mbar) at the National Ignition Facility are shown.

Thermophysical properties of multi-shock compressed dense argon.

Science.gov (United States)

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

2014-02-21

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

PIV tracer behavior on propagating shock fronts

International Nuclear Information System (INIS)

Glazyrin, Fyodor N; Mursenkova, Irina V; Znamenskaya, Irina A

2016-01-01

The present work was aimed at the quantitative particle image velocimetry (PIV) measurement of a velocity field near the front of a propagating shock wave and the study of the dynamics of liquid tracers crossing the shock front. For this goal, a shock tube with a rectangular cross-section (48  ×  24 mm) was used. The flat shock wave with Mach numbers M  =  1.4–2.0 propagating inside the tube channel was studied as well as an expanding shock wave propagating outside the channel with M  =  1.2–1.8 at its main axis. The PIV imaging of the shock fronts was carried out with an aerosol of dioctyl sebacate (DEHS) as tracer particles. The pressures of the gas in front of the shock waves studied ranged from 0.013 Mpa to 0.1 MPa in the series of experiments. The processed PIV data, compared to the 1D normal shock theory, yielded consistent values of wake velocity immediately behind the plain shock wave. Special attention was paid to the blurring of the velocity jump on the shock front due to the inertial particle lag and peculiarities of the PIV technique. A numerical algorithm was developed for analysis and correction of the PIV data on the shock fronts, based on equations of particle-flow interaction. By application of this algorithm, the effective particle diameter of the DEHS aerosol tracers was estimated as 1.03  ±  0.12 μm. A number of different formulations for particle drag were tested with this algorithm, with varying success. The results show consistency with previously reported experimental data obtained for cases of stationary shock waves. (paper)

Optoheterodyne Doppler measurements of the ballistic expansion of the products of the shock wave-induced surface destruction: Experiment and theory

International Nuclear Information System (INIS)

Andriyash, A. V.; Astashkin, M. V.; Baranov, V. K.; Golubinskii, A. G.; Irinichev, D. A.; Kondrat’ev, A. N.; Kuratov, S. E.; Mazanov, V. A.; Rogozkin, D. B.; Stepushkin, S. N.; Khatunkin, V. Yu.

2016-01-01

The results of optoheterodyne Doppler measurements of the ballistic expansion of the products of surface destruction under shock-wave loading are presented. The possibility of determining the physical characteristics of a rapidly flying dust cloud, including the microparticle velocities, the microparticle sizes, and the areal density of the dust cloud, is shown. A compact stand for performing experiments on shock-wave loading of metallic samples is described. Shock-wave loading is performed by a 100-µm-thick tantalum flyer plate accelerated to a velocity of 2.8 km/s. As the samples, lead plates having various thicknesses and the same surface roughness are used. At a shock-wave pressure of 31.5 GPa, the destruction products are solid microparticles about 50 µm in size. At a pressure of 42 and 88 GPa, a liquid-drop dust cloud with a particle size of 10–15 µm is formed. To interpret the spectral data on the optoheterodyne Doppler measurements of the expansion of the surface destruction products (spalled fragments, dust microparticles), a transport equation for the function of mutual coherence of a multiply scattered field is used. The Doppler spectra of a backscattered signal are calculated with the model developed for the dust cloud that appears when a shock wave reaches the sample surface at the parameters that are typical of an experimental situation. Qualitative changes are found in the spectra, depending on the optical thickness of the dust cloud. The obtained theoretical results are in agreement with the experimental data.

Optoheterodyne Doppler measurements of the ballistic expansion of the products of the shock wave-induced surface destruction: Experiment and theory

Energy Technology Data Exchange (ETDEWEB)

Andriyash, A. V. [All-Russia Research Institute of Automatics (Russian Federation); Astashkin, M. V.; Baranov, V. K.; Golubinskii, A. G.; Irinichev, D. A. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Kondrat’ev, A. N., E-mail: an.kondratev@physics.msu.ru; Kuratov, S. E. [All-Russia Research Institute of Automatics (Russian Federation); Mazanov, V. A. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (VNIIEF) (Russian Federation); Rogozkin, D. B. [All-Russia Research Institute of Automatics (Russian Federation); Stepushkin, S. N.; Khatunkin, V. Yu. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (VNIIEF) (Russian Federation)

2016-06-15

The results of optoheterodyne Doppler measurements of the ballistic expansion of the products of surface destruction under shock-wave loading are presented. The possibility of determining the physical characteristics of a rapidly flying dust cloud, including the microparticle velocities, the microparticle sizes, and the areal density of the dust cloud, is shown. A compact stand for performing experiments on shock-wave loading of metallic samples is described. Shock-wave loading is performed by a 100-µm-thick tantalum flyer plate accelerated to a velocity of 2.8 km/s. As the samples, lead plates having various thicknesses and the same surface roughness are used. At a shock-wave pressure of 31.5 GPa, the destruction products are solid microparticles about 50 µm in size. At a pressure of 42 and 88 GPa, a liquid-drop dust cloud with a particle size of 10–15 µm is formed. To interpret the spectral data on the optoheterodyne Doppler measurements of the expansion of the surface destruction products (spalled fragments, dust microparticles), a transport equation for the function of mutual coherence of a multiply scattered field is used. The Doppler spectra of a backscattered signal are calculated with the model developed for the dust cloud that appears when a shock wave reaches the sample surface at the parameters that are typical of an experimental situation. Qualitative changes are found in the spectra, depending on the optical thickness of the dust cloud. The obtained theoretical results are in agreement with the experimental data.

Simulations of Converging Shock Collisions for Shock Ignition

Science.gov (United States)

Sauppe, Joshua; Dodd, Evan; Loomis, Eric

2016-10-01

Shock ignition (SI) has been proposed as an alternative to achieving high gain in inertial confinement fusion (ICF) targets. A central hot spot below the ignition threshold is created by an initial compression pulse, and a second laser pulse drives a strong converging shock into the fuel. The collision between the rebounding shock from the compression pulse and the converging shock results in amplification of the converging shock and increases the hot spot pressure above the ignition threshold. We investigate shock collision in SI drive schemes for cylindrical targets with a polystyrene foam interior using radiation-hydrodynamics simulations with the RAGE code. The configuration is similar to previous targets fielded on the Omega laser. The CH interior results in a lower convergence ratio and the cylindrical geometry facilitates visualization of the shock transit using an axial X-ray backlighter, both of which are important for comparison to potential experimental measurements. One-dimensional simulations are used to determine shock timing, and the effects of low mode asymmetries in 2D computations are also quantified. LA-UR-16-24773.

Absolute Hugoniot measurements from a spherically convergent shock using x-ray radiography

Science.gov (United States)

Swift, Damian C.; Kritcher, Andrea L.; Hawreliak, James A.; Lazicki, Amy; MacPhee, Andrew; Bachmann, Benjamin; Döppner, Tilo; Nilsen, Joseph; Collins, Gilbert W.; Glenzer, Siegfried; Rothman, Stephen D.; Kraus, Dominik; Falcone, Roger W.

2018-05-01

The canonical high pressure equation of state measurement is to induce a shock wave in the sample material and measure two mechanical properties of the shocked material or shock wave. For accurate measurements, the experiment is normally designed to generate a planar shock which is as steady as possible in space and time, and a single state is measured. A converging shock strengthens as it propagates, so a range of shock pressures is induced in a single experiment. However, equation of state measurements must then account for spatial and temporal gradients. We have used x-ray radiography of spherically converging shocks to determine states along the shock Hugoniot. The radius-time history of the shock, and thus its speed, was measured by radiographing the position of the shock front as a function of time using an x-ray streak camera. The density profile of the shock was then inferred from the x-ray transmission at each instant of time. Simultaneous measurement of the density at the shock front and the shock speed determines an absolute mechanical Hugoniot state. The density profile was reconstructed using the known, unshocked density which strongly constrains the density jump at the shock front. The radiographic configuration and streak camera behavior were treated in detail to reduce systematic errors. Measurements were performed on the Omega and National Ignition Facility lasers, using a hohlraum to induce a spatially uniform drive over the outside of a solid, spherical sample and a laser-heated thermal plasma as an x-ray source for radiography. Absolute shock Hugoniot measurements were demonstrated for carbon-containing samples of different composition and initial density, up to temperatures at which K-shell ionization reduced the opacity behind the shock. Here we present the experimental method using measurements of polystyrene as an example.

Shock wave equation of state of powder material

OpenAIRE

Dijken, D.K.; Hosson, J.Th.M. De

1994-01-01

A model is proposed to predict the following quantities for powder materials compacted by shock waves: the pressure, the specific volume, the internal energy behind the shock wave, and the shock-wave velocity U-s. They are calculated as a function of flyerplate velocity u(p) and initial powder specific volume V-00. The model is tested on Cu, Al2024, and Fe. Calculated U-s vs u(p) curves agree well with experiments provided V-00 is smaller than about two times the solid specific volume. The mo...

Measuring the flexoelectric coefficient of bulk barium titanate from a shock wave experiment

Science.gov (United States)

Hu, Taotao; Deng, Qian; Liang, Xu; Shen, Shengping

2017-08-01

In this paper, a phenomenon of polarization introduced by shock waves is experimentally studied. Although this phenomenon has been reported previously in the community of physics, this is the first time to link it to flexoelectricity, the coupling between electric polarization and strain gradients in dielectrics. As the shock waves propagate in a dielectric material, electric polarization is thought to be induced by the strain gradient at the shock front. First, we control the first-order hydrogen gas gun to impact and generate shock waves in unpolarized bulk barium titanate (BT) samples. Then, a high-precision oscilloscope is used to measure the voltage generated by the flexoelectric effect. Based on experimental results, strain elastic wave theory, and flexoelectric theory, a longitudinal flexoelectric coefficient of the bulk BT sample is calculated to be μ 11 = 17.33 × 10 - 6 C/m, which is in accord with the published transverse flexoelectric coefficient. This method effectively suppresses the majority of drawbacks in the quasi-static and low frequency dynamic techniques and provides more reliable results of flexoelectric behaviors.

Acculturative Experiences Among Indonesian Graduate Students in US Higher Education: Academic Shock, Adjustment, Crisis, and Resolution

Directory of Open Access Journals (Sweden)

Amirul Mukminin

2012-06-01

Full Text Available The purpose of this qualitative inquiry was to describe and understand the lived experiences of the acculturative process of Indonesian graduate students at an American public research university. The theoretical frameworks of Oberg’s (1960 Culture Shock Model and Berry and his colleagues’ (1987 and Berry’s (2006 Acculturation Stress Model were used to guide this study. Data for this study were collected through a demographic background survey, in-depth interviews, and focus group discussions with Indonesian graduate students. The demographic data were analyzed descriptively. The interviews and focus groups data were analyzed using within-case and cross-case displays and analyses (Miles and Huberman 1994. Five salient themes and sub-themes that emerged were: academic shock, adjustment, crisis, resolution, and what helps/does not help? Implications and strategies for professionals and scholars who work with international students in practice, education, and policy are discussed. In addition, strategies to promote Indonesian graduate students’ academic and social success in graduate programs are included. Suggestions for future research are also discussed.

LIGS measurements in the nozzle reservoir of a free-piston shock tunnel

Science.gov (United States)

Altenhöfer, P.; Sander, T.; Koroll, F.; Mundt, Ch.

2018-02-01

Free-piston shock tunnels are ground-based test facilities allowing the simulation of reentry flow conditions in a simple and cost-efficient way. For a better understanding of the processes occurring in a shock tunnel as well as for an optimal comparability of experimental data gained in shock tunnels to numerical simulations, it is highly desirable to have the best possible characterization of the generated test gas flows. This paper describes the final step of the development of a laser-induced grating spectroscopy (LIGS) system capable of measuring the temperature in the nozzle reservoir of a free-piston shock tunnel during tests: the successful adaptation of the measurement system to the shock tunnel. Preliminary measurements were taken with a high-speed camera and a LED lamp in order to investigate the optical transmissibility of the measurement volume during tests. The results helped to successfully measure LIGS signals in shock tube mode and shock tunnel mode in dry air seeded with NO. For the shock tube mode, six successful measurements for a shock Mach number of about 2.35 were taken in total, two of them behind the incoming shock (p ≈ 1 MPa, T ≈ 600 K) and four after the passing of the reflected shock (p ≈ 4 MPa, T ≈ 1000 K). For five of the six measurements, the derived temperatures were within a deviation range of 6% to a reference value calculated from measured shock speed. The uncertainty estimated was less than or equal to 3.5% for all six measurements. Two LIGS signals from measurements behind the reflected shock in shock tunnel mode were analyzed in detail. One of the signals allowed an unambiguous derivation of the temperature under the conditions of a shock with Mach 2.7 (p ≈ 5 MPa, T ≈ 1200 K, deviation 0.5% , uncertainty 4.9% ).

Spherical shock-ignition experiments with the 40 + 20-beam configuration on OMEGA

Energy Technology Data Exchange (ETDEWEB)

Theobald, W.; Anderson, K. S.; Delettrez, J. A.; Glebov, V. Yu.; Gotchev, O. V.; Hohenberger, M.; Hu, S. X.; Marshall, F. J.; Sangster, T. C.; Seka, W.; Stoeckl, C.; Yaakobi, B. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Nora, R.; Betti, R.; Meyerhofer, D. D. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Department of Mechanical Engineering and Physics at the University of Rochester, Rochester, New York 14623 (United States); Lafon, M. [Laboratory for Laser Energetics and Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); University of Bordeaux, CEA, CNRS, CELIA (Centre Lasers Intenses et Applications), F-33400 Talence (France); Casner, A. [CEA, DAM, DIF, F-91297 Arpajon (France); Ribeyre, X.; Schurtz, G. [University of Bordeaux, CEA, CNRS, CELIA (Centre Lasers Intenses et Applications), F-33400 Talence (France); Frenje, J. A. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); and others

2012-10-15

Spherical shock-ignition experiments on OMEGA used a novel beam configuration that separates low-intensity compression beams and high-intensity spike beams. Significant improvements in the performance of plastic-shell, D{sub 2} implosions were observed with repointed beams. The analysis of the coupling of the high-intensity spike beam energy into the imploding capsule indicates that absorbed hot-electron energy contributes to the coupling. The backscattering of laser energy was measured to reach up to 36% at single-beam intensities of {approx}8 Multiplication-Sign 10{sup 15} W/cm{sup 2}. Hard x-ray measurements revealed a relatively low hot-electron temperature of {approx}30 keV independent of intensity and timing. At the highest intensity, stimulated Brillouin scattering occurs near and above the quarter-critical density and the two-plasmon-decay instability is suppressed.

Shock interaction with a two-gas interface in a novel dual-driver shock tube

Science.gov (United States)

Labenski, John R.

Fluid instabilities exist at the interface between two fluids having different densities if the flow velocity and density gradient are anti-parallel or if a shock wave crosses the boundary. The former case is called the Rayleigh-Taylor (R-T) instability and the latter, the Richtmyer-Meshkov (R-M) instability. Small initial perturbations on the interface destabilize and grow into larger amplitude structures leading to turbulent mixing. Instabilities of this type are seen in inertial confinement fusion (ICF) experiments, laser produced plasmas, supernova explosions, and detonations. A novel dual-driver shock tube was used to investigate the growth rate of the R-M instability. One driver is used to create an argon-refrigerant interface, and the other at the opposite end of the driven section generates a shock to force the interface with compressible flows behind the shock. The refrigerant gas in the first driver is seeded with sub-micron oil droplets for visualization of the interface. The interface travels down the driven section past the test section for a fixed amount of time. A stronger shock of Mach 1.1 to 1.3 drives the interface back past the test section where flow diagnostics are positioned. Two schlieren systems record the density fluctuations while light scattering detectors record the density of the refrigerant as a function of position over the interface. A pair of digital cameras take stereo images of the interface, as mapped out by the tracer particles under illumination by a Q-switched ruby laser. The amount of time that the interface is allowed to travel up the driven section determines the interaction time as a control. Comparisons made between the schlieren signals, light scattering detector outputs, and the images quantify the fingered characteristics of the interface and its growth due to shock forcing. The results show that the interface has a distribution of thickness and that the interaction with a shock further broadens the interface. The

Molecular dynamics of shock waves in one-dimensional chains. II. Thermalization

International Nuclear Information System (INIS)

Straub, G.K.; Holian, B.L.; Petschek, R.G.

1979-01-01

The thermalization behavior behind a shock front in one-dimensional chains has been studied in a series of molecular-dynamics computer experiments. We have found that a shock wave generated in a chain initially at finite temperature has essentially the same characteristics as in a chain initially at zero temperature. We also find that the final velocity distribution function for particles behind the shock front is not the Maxwell-Boltzmann distribution for an equilibrium system of classical particles. For times long after the shock has passed, we propose a nonequilibrium velocity distribution which is based upon behavior in the harmonic and hard-rod limits and agrees with our numerical results. Temperature profiles for both harmonic and anharmonic chains are found to exhibit a long-time tail that decays inversely with time. Finally, we have run a computer experiment to generate what qualitatively resembles solitons in Toda chains by means of shock waves

Measuring the shock impedance mismatch between high-density carbon and deuterium at the National Ignition Facility

Science.gov (United States)

Millot, M.; Celliers, P. M.; Sterne, P. A.; Benedict, L. X.; Correa, A. A.; Hamel, S.; Ali, S. J.; Baker, K. L.; Berzak Hopkins, L. F.; Biener, J.; Collins, G. W.; Coppari, F.; Divol, L.; Fernandez-Panella, A.; Fratanduono, D. E.; Haan, S. W.; Le Pape, S.; Meezan, N. B.; Moore, A. S.; Moody, J. D.; Ralph, J. E.; Ross, J. S.; Rygg, J. R.; Thomas, C.; Turnbull, D. P.; Wild, C.; Eggert, J. H.

2018-04-01

Fine-grained diamond, or high-density carbon (HDC), is being used as an ablator for inertial confinement fusion (ICF) research at the National Ignition Facility (NIF). Accurate equation of state (EOS) knowledge over a wide range of phase space is critical in the design and analysis of integrated ICF experiments. Here, we report shock and release measurements of the shock impedance mismatch between HDC and liquid deuterium conducted during shock-timing experiments having a first shock in the ablator ranging between 8 and 14 Mbar. Using ultrafast Doppler imaging velocimetry to track the leading shock front, we characterize the shock velocity discontinuity upon the arrival of the shock at the HDC/liquid deuterium interface. Comparing the experimental data with tabular EOS models used to simulate integrated ICF experiments indicates the need for an improved multiphase EOS model for HDC in order to achieve a significant increase in neutron yield in indirect-driven ICF implosions with HDC ablators.

Defining Moments in MMWR History: Toxic-Shock Syndrome -- 1980

Centers for Disease Control (CDC) Podcasts

2017-11-03

In the late 1970s and early 1980s, an outbreak of a disease called Toxic Shock Syndrome made healthy women sick. CDC’s disease detectives helped unravel the link between Toxic Shock Syndrome and high-absorbency tampons. MMWR was the first scientific publication to break the news of these cases. In this podcast, Dr. Kathy Shands, former chief of CDC’s Toxic Shock Syndrome Task Force, recalls her experience working with state epidemiologists to identify the link between toxic shock syndrome and tampon use.  Created: 11/3/2017 by MMWR.   Date Released: 11/3/2017.

Shock compaction of molybdenum powder

Science.gov (United States)

Ahrens, T. J.; Kostka, D.; Vreeland, T., Jr.; Schwarz, R. B.; Kasiraj, P.

1983-01-01

Shock recovery experiments which were carried out in the 9 to 12 GPa range on 1.4 distension Mo and appear adequate to compact to full density ( 45 (SIGMA)m) powders were examined. The stress levels, however, are below those calculated to be from 100 to approx. 22 GPa which a frictional heating model predicts are required to consolidate approx. 10 to 50 (SIGMA)m particles. The model predicts that powders that have a distension of m=1.6 shock pressures of 14 to 72 GPa are required to consolidate Mo powders in the 50 to 10 (SIGMA)m range.

Jet formation in shock-heavy gas bubble interaction

Institute of Scientific and Technical Information of China (English)

Zhi-Gang Zhai; Ting Si; Li-Yong Zou; Xi-Sheng Luo

2013-01-01

The influences of the acoustic impedance and shock strength on the jet formation in shock-heavy gas bubble interaction are numerically studied in this work.The process of a shock interacting with a krypton or a SF6 bubble is studied by the numerical method VAS2D.As a validation,the experiments of a SF6 bubble accelerated by a planar shock were performed.The results indicate that,due to the mismatch of acoustic impedance,the way of jet formation in heavy gas bubble with different species is diversified under the same initial condition.With respect to the same bubble,the manner of jet formation is also distinctly different under different shock strengths.The disparities of the acoustic impedance result in different effects of shock focusing in the bubble,and different behaviors of shock wave inside and outside the bubble.The analyses of the wave pattern and the pressure variation indicate that the jet formation is closely associated with the pressure perturbation.Moreover,the analysis of the vorticity deposition,and comparisons of circulation and baroclinic torque show that the baroclinic vorticity also contributes to the jet formation.It is concluded that the pressure perturbation and baroclinic vorticity deposition are the two dominant factors for the jet formation in shock-heavy gas bubble interaction.

Unusual behaviour of usual materials in shock waves

International Nuclear Information System (INIS)

Kanel, G I

2014-01-01

Exotic results of investigations of inelastic deformation and fracture under shock wave loading are presented and briefly discussed. Temperature effects on the flow stress at high strain rate may differ even in sign from those we observe at low and moderate strain rates. Investigations of the temperature-rate dependence of the yield stress at shock compression demonstrate intense multiplication of dislocations. At the highest strain rates, so-called ideal (ultimate) shear and tensile strength is reached in experiments with picosecond durations of shock loading. Although grain boundaries, in general, reduce resistance to fracture as compared to single crystals, the spall strength of ultra-fine-grained metals usually slightly exceeds that of coarse-grain samples. Failure wave phenomena have been observed in shock-compressed glasses.

Revisiting the thermal effect on shock wave propagation in weakly ionized plasmas

International Nuclear Information System (INIS)

Zhou, Qianhong; Dong, Zhiwei; Yang, Wei

2016-01-01

Many researchers have investigated shock propagation in weakly ionized plasmas and observed the following anomalous effects: shock acceleration, shock recovery, shock weakening, shock spreading, and splitting. It was generally accepted that the thermal effect can explain most of the experimental results. However, little attention was paid to the shock recovery. In this paper, the shock wave propagation in weakly ionized plasmas is studied by fluid simulation. It is found that the shock acceleration, weakening, and splitting appear after it enters the plasma (thermal) region. The shock splits into two parts right after it leaves the thermal region. The distance between the splitted shocks keeps decreasing until they recover to one. This paper can explain a whole set of features of the shock wave propagation in weakly ionized plasmas. It is also found that both the shock curvature and the splitting present the same photoacoustic deflection (PAD) signals, so they cannot be distinguished by the PAD experiments.

Shock recovery experiments in the range of 10 to 45 GPa - comparison of results of synthetic magnetite and terrestrial diabase

Czech Academy of Sciences Publication Activity Database

Kohout, Tomáš; Pesonen, L.; Deutsch, A.; Honnermann, U.

89 /53/, Fall Meeting Supplement (2008), , GP21C-0790-GP21C-0790 ISSN 0096-3941. [American Geophysical Union Fall Meeting. 15.12.2008-19.12.2008, San Francisco] Institutional research plan: CEZ:AV0Z30130516 Keywords : shock experiments * magnetite * diabase Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=table&application=fm08&convert=&converthl=&refinequery=&formintern=&formextern=&transquery=kohout&_lines=&multiple=0&descriptor=%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c766%7c5433%7cShock%20recovery%20experiments%20in%20the%20range%20of%2010%20to%2045%20GPa%20-%20comparison%20of%20results%20of%20synthetic%20magnetite%20and%20terrestrial%20diabase%7cHTML%7clocalhost:0%7c%2fdata%2fepubs%2fwais%2findexes%2ffm08%2ffm08%7c19257669%2019263102%20%2fdata2%2fepubs%2fwais%2fdata%2ffm08%2ffm08.txt

The effects of salinity and temperature shock on Kappaphycus alvarezii seaweed spores release

Science.gov (United States)

Harwinda, F. K.; Satyantini, W. H.; Masithah, E. W.

2018-04-01

One of the reproductive aspects of development step that is considered as the solution of this issue is seaweed sporulation technique through which is induced through salinity and temperature shock. This study aims to determine the effect of combination and interaction of salinity and temperature shock on the release of K. alvarezii spores in order to produce superior seeds. This research was conducted using Complete Randomized Design Factorial which consists of nine combinations of treatments and three replications. The used treatment in this study is the combination of different environmental factors such as salinity shock and temperature shock. The data were analyzed using ANOVA (Analysis of Variance) followed by Duncan Multiple Range Test. The results showed that salinity (31 ppt, 33 ppt, and 35 ppt) and temperature (30°C, 32°C, and 34°C). shock affected the osmoregulation system and the release of K. alvarezii spores. The salinity shock and temperature shock had interaction with K. alvarezii spore release on the sixth and seventh day with the best treatment at 32°C temperature and 31 ppt salinity and released 5413 cells/ml spores on the seventh day.

Have shock waves been observed in nuclear collisions

International Nuclear Information System (INIS)

Gudima, K.K.; Toneev, V.D.

Experimental data on shock wave phenomena in nuclear reactions are analyzed within the kinetic theory rather than that of the hydrodynamic approach. Beginning with a presentation of the model, which is a generalization of the cascade--evaporation model to the case of the interaction of two nuclei, it is then ascertained to what degree the developed approach is valid. Next on the basis of this model the results of experiments performed are examined to find the effects of a shock wave. The results of this analysis and the related set-up of new experiments are discussed also. 34 references

Shock tubes: compressions in the low pressure chamber

International Nuclear Information System (INIS)

Schins, H.; Giuliani, S.

1986-01-01

The gas shock tube used in these experiments consists of a low pressure chamber and a high pressure chamber, divided by a metal-diaphragm-to-rupture. In contrast to the shock mode of operation, where incident and reflected shocks in the low pressure chamber are studied which occur within 3.5 ms, in this work the compression mode of operation was studied, whose maxima occur (in the low pressure chamber) about 9 ms after rupture. Theoretical analysis was done with the finite element computer code EURDYN-1M, where the computation was carried out to 30 ms

Phantom shocks in patients with implantable cardioverter defibrillator

DEFF Research Database (Denmark)

Berg, Selina Kikkenborg; Moons, Philip; Zwisler, Ann-Dorthe

2013-01-01

of phantom shocks.METHODS AND RESULTS: The design was secondary explorative analyses of data from a randomized controlled trial. One hundred and ninety-six patients with first-time ICD implantation (79% male, mean age 58 years) were randomized (1 : 1) to either combined rehabilitation or a control group...... questions regarding the experience of phantom shocks, date, time, and place. Twelve patients (9.4%) experienced a phantom shock, 7 in the intervention group and 5 in the control group (NS). Neither age, sex, quality of life nor perceived health at baseline was significantly related to the probability...

Shock characterization of an ultra-high strength concrete

International Nuclear Information System (INIS)

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

2016-01-01

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. (authors)

Shock wave synthesis of amino acids from solutions of ammonium formate and ammonium bicarbonate

Science.gov (United States)

Suzuki, Chizuka; Furukawa, Yoshihiro; Kobayashi, Takamichi; Sekine, Toshimori; Nakazawa, Hiromoto; Kakegawa, Takeshi

2015-07-01

The emergence of life's building blocks, such as amino acids and nucleobases, on the prebiotic Earth was a critical step for the beginning of life. Reduced species with low mass, such as ammonia, amines, or carboxylic acids, are potential precursors for these building blocks of life. These precursors may have been provided to the prebiotic ocean by carbonaceous chondrites and chemical reactions related to meteorite impacts on the early Earth. The impact of extraterrestrial objects on Earth occurred more frequently during this period than at present. Such impacts generated shock waves in the ocean, which have the potential to progress chemical reactions to form the building blocks of life from reduced species. To simulate shock-induced reactions in the prebiotic ocean, we conducted shock-recovery experiments on ammonium bicarbonate solution and ammonium formate solution at impact velocities ranging from 0.51 to 0.92 km/s. In the products from the ammonium formate solution, several amino acids (glycine, alanine, ß-alanine, and sarcosine) and aliphatic amines (methylamine, ethylamine, propylamine, and butylamine) were detected, although yields were less than 0.1 mol % of the formic acid reactant. From the ammonium bicarbonate solution, smaller amounts of glycine, methylamine, ethylamine, and propylamine were formed. The impact velocities used in this study represent minimum cases because natural meteorite impacts typically have higher velocities and longer durations. Our results therefore suggest that shock waves could have been involved in forming life's building blocks in the ocean of prebiotic Earth, and potentially in aquifers of other planets, satellites, and asteroids.

Fast-shock ignition: a new approach to inertial confinement fusion

Directory of Open Access Journals (Sweden)

AH Farahbod

2013-03-01

Full Text Available  A new concept for inertial confinement fusion called fast-shock ignition (FSI is introduced as a credible scheme in order to obtain high target gain. In the proposed model, the separation of fuel ignition into two successive steps, under the suitable conditions, reduces required ignitor energy for the fuel ignition. The main procedure in FSI concept is compressing the fuel up to stagnation. Then, two high intensity short pulse laser spikes with energy and power lower than those required for shock ignition (SI and fast ignition (FI with a proper delay time are launched at the fuel which increases the central hot-spot temperature and completes the ignition of the precompressed fuel. The introduced semi-analytical model indicates that with fast-shock ignition, the total required energy for compressing and igniting the fuel can be slightly reduced in comparison to pure shock ignition. Furthermore, for fuel mass greater than , the target energy gain increases up to 15 percent and the contribution of fast ignitor under the proper conditions could be decreased about 20 percent compared with pure fast ignition. The FSI scheme is beneficial from technological considerations for the construction of short pulse high power laser drivers. The general advantages of fast-shock ignition over pure shock ignition in terms of figure of merit can be more than 1.3.

Experience with extracorporeal shock wave therapy (ESWT) in the United States

Science.gov (United States)

Furia, John P.

2005-04-01

The purpose of this presentation is to summarize the literature and to report on single treatment, high-energy ESWT for the treatment of chronic plantar fasciitis and lateral epicondylitis. Fifty-three patients (60 heels) were treated with 3800 shock waves. Sixteen patients (19 heels) were active, 21 (22 heels), were moderately active, and 16 (19 heels) were sedentary. Twelve weeks post treatment, mean visual analog scores (VAS) for the entire group improved from 9.2 to 2.4 (plateral epicondylitis were treated with 3200 shock waves. There were 9 workers compensation and 27 non-workers compensation patients. Twelve weeks post treatment, the mean VAS for the entire group improved from 8.0 to 2.5 (plateral epicondylitis.

Economic Shocks and Subjective Well-Being

DEFF Research Database (Denmark)

Hariri, Jacob Gerner; Bjørnskov, Christian; Justesen, Mogens Kamp

This paper examines how economic shocks affect individual well-being in developing countries. Using the case of a sudden and unanticipated currency devaluation in Botswana as a quasi-experiment, we examine how this monetary shock affects individuals’ evaluations of well-being. We do so by using...... micro-level survey data, which – incidentally – was collected in the days surrounding the devaluation. The chance occurrence of the devaluation during the time of the survey enables us to use pre-treatment respondents, surveyed before the devaluation, as approximate counterfactuals for post......-treatment respondents, surveyed after the devaluation. Our estimates show that the devaluation had a large and significantly negative effect on individuals’ evaluations of subjective well-being. These results suggest that macroeconomic shocks, such as unanticipated currency devaluations, may have significant short...

Economic Shocks and Subjective Well-being

DEFF Research Database (Denmark)

Hariri, Jacob Gerner; Bjørnskov, Christian; Justesen, Mogens Kamp

This paper examines how economic shocks affect individual well-being in developing countries. Using the case of a sudden and unanticipated currency devaluation in Botswana as a quasi-experiment, we examine how this monetary shock affects individuals’ evaluations of well-being. We do so by using...... micro-level survey data, which – incidentally – was collected in the days surrounding the devaluation. The chance occurrence of the devaluation during the time of the survey enables us to use pre-treatment respondents, surveyed before the devaluation, as approximate counterfactuals for post......-treatment respondents, surveyed after the devaluation. Our estimates show that the devaluation had a large and significantly negative effect on individuals’ evaluations of subjective well-being. These results suggest that macroeconomic shocks, such as unanticipated currency devaluations, may have significant short...

Tolerance of Artemia to static and shock pressure loading

Science.gov (United States)

Fitzmaurice, B. C.; Appleby-Thomas, G. J.; Painter, J. D.; Ono, F.; McMillan, P. F.; Hazael, R.; Meersman, F.

2017-10-01

Hydrostatic and hydrodynamic pressure loading has been applied to unicellular organisms for a number of years due to interest from food technology and extremophile communities. There is also an emerging interest in the response of multicellular organisms to high pressure conditions. Artemia salina is one such organism. Previous experiments have shown a marked difference in the hatching rate of these organisms after exposure to different magnitudes of pressure, with hydrostatic tests showing hatching rates at pressures up to several GPa, compared to dynamic loading that resulted in comparatively low survival rates at lower pressure magnitudes. In order to begin to investigate the origin of this difference, the work presented here has focussed on the response of Artemia salina to (quasi) one-dimensional shock loading. Such experiments were carried out using the plate-impact technique in order to create a planar shock front. Artemia cysts were investigated in this manner along with freshly hatched larvae (nauplii). The nauplii and cysts were observed post-shock using optical microscopy to detect motility or hatching, respectively. Hatching rates of 18% were recorded at pressures reaching 1.5 GPa, as determined with the aid of numerical models. Subjecting Artemia to quasi-one-dimensional shock loading offers a way to more thoroughly explore the shock pressure ranges these organisms can survive.

Slow shocks and their transition to fast shocks in the inner solar wind

International Nuclear Information System (INIS)

Wang, Y.C.

1987-01-01

The jump conditions of MHD shocks may be directly calculated as functions of three upstream conditions: the shock Alfven number based on the normal component of the relative shock speed, the shock angle, and the plasma β value. The shock Alfven number is less than 1 for a slow shock and greater than 1 for a fast shock. A traveling, forward shock can be a slow shock in coronal space, where the Alfven speed is of the order of 1000 km/s. The surface of a forward slow shock has a bow-shaped geometry with its nose facing toward the sun. The decrease in the Alfven speed at increasing heliocentric distance causes the shock Alfven number of a forward slow shock to become greater than 1, and the shock eventually evolves from a slow shock into a fast shock. During the transition the shock system consists of a slow shock, a fast shock, and a rotational discontinuity. They intersect along a closed transition line. As the system moves outward from the sun, the area enclosed by the transition line expands, the fast shock grows stronger, and the slow shock becomes weaker. Eventually, the slow shock diminishes, and the entire shock system evolves into a forward fast shock. copyrightAmerican Geophysical Union 1987

Effects of prior aversive experience upon retrograde amnesia induced by hypothermia.

Science.gov (United States)

Jensen, R A; Riccio, D C; Gehres, L

1975-08-01

Two experiments examined the extent to which retrograde amnesia (RA) is attenuated by prior learning experiences. In Experiment 1, rats initially received either passive avoidance training in a step-through apparatus, exposure to the apparatus, or noncontingent footshock. When training on a second but different passive avoidance task was followed by hypothermia treatment, RA was obtained only in the latter two groups. In Experiment 2, one-way active avoidance training, yoked noncontingent shocks, or apparatus exposure constituted the initial experience. Subsequent step-down passive avoidance training and amnestic treatment resulted in memory loss for the prior apparatus exposure group, but not for either of the preshocked conditions. These experiments demonstrate that certain types of prior aversive experience can substantially modify the magnitude of RA, and, in conjunction with other familiarization studies, emphasize a paradox for interpretations of RA based solely upon CNS disruption. The possibility that hypothermia treatment serves as an important contextual or encoding cue necessary for memory retrieval was considered. It was suggested that prior experience may block RA by enabling rats to differentiate training and treatment conditions.

Shock wave overtake measurements on cesium iodide

International Nuclear Information System (INIS)

Swenson, C.A.

1986-01-01

The luminosity of the shock front for CsI makes it an ideal material for which to measure directly sound velocities along the Hugoniot using shock wave overtake methods. In these measurements, the occurrence of melting along the Hugoniot is marked by a discontinuous decrease in the measured sound velocity. In addition, CsI is isoelectronic with xenon and is expected to begin to show metallic behavior along the Hugoniot near 0.9 Mbar. The directly-determined sound velocities and corresponding elastic moduli would be expected to be more sensitive to this transition than either Hugoniot equations of state or optical pyrometry experiments. This paper presents a brief description of the present experiments and results

Nonrelativistic grey Sn-transport radiative-shock solutions

International Nuclear Information System (INIS)

Ferguson, J. M.; Morel, J. E.; Lowrie, R. B.

2017-01-01

We present semi-analytic radiative-shock solutions in which grey Sn-transport is used to model the radiation, and we include both constant cross sections and cross sections that depend on temperature and density. These new solutions solve for a variable Eddington factor (VEF) across the shock domain, which allows for interesting physics not seen before in radiative-shock solutions. Comparisons are made with the grey nonequilibrium-diffusion radiative-shock solutions of Lowrie and Edwards [1], which assumed that the Eddington factor is constant across the shock domain. It is our experience that the local Mach number is monotonic when producing nonequilibrium-diffusion solutions, but that this monotonicity may disappear while integrating the precursor region to produce Sn-transport solutions. For temperature- and density-dependent cross sections we show evidence of a spike in the VEF in the far upstream portion of the radiative-shock precursor. We show evidence of an adaptation zone in the precursor region, adjacent to the embedded hydrodynamic shock, as conjectured by Drake [2, 3], and also confirm his expectation that the precursor temperatures adjacent to the Zel’dovich spike take values that are greater than the downstream post-shock equilibrium temperature. We also show evidence that the radiation energy density can be nonmonotonic under the Zel’dovich spike, which is indicative of anti-diffusive radiation flow as predicted by McClarren and Drake [4]. We compare the angle dependence of the radiation flow for the Sn-transport and nonequilibriumdiffusion radiation solutions, and show that there are considerable differences in the radiation flow between these models across the shock structure. Lastly, we analyze the radiation flow to understand the cause of the adaptation zone, as well as the structure of the Sn-transport radiation-intensity solutions across the shock structure.

Thermal shock considerations for the TFCX limiter and first wall

International Nuclear Information System (INIS)

Haines, J.R.; Fuller, G.M.

1983-01-01

Resistance to thermal shock fracture of limiter and first wall surface material candidates during plasma disruption heating conditions is evaluated. A simple, figure-of-merit type thermal shock parameter which provides a mechanism to rank material candidates is derived. Combining this figure-of-merit parameter with the parameters defining specific heating conditions yields a non-dimensional thermal shock parameter. For values of this parameter below a critical value, a given material is expected to undergo thermal shock damage. Prediction of thermal shock damage with this parameter is shown to exhibit good agreement with test data. Applying this critical parameter value approach, all materials examined in this study are expected to experience thermal shock damage for nominal TFCX plasma disruption conditions. Since the extent of this damage is not clear, tests which explore the range of expected conditions for TFCX are recommended

Analytical criterion for shock ignition of fusion reaction in hot spot

International Nuclear Information System (INIS)

Ribeyre, X.; Tikhonchuk, V. T.; Breil, J.; Lafon, M.; Vallet, A.; Bel, E. L.

2013-01-01

Shock ignition of DT capsules involves two major steps. First, the fuel is assembled by means of a low velocity conventional implosion. At stagnation, the central core has a temperature lower than the one needed for ignition. Then a second, strong spherical converging shock, launched from a high intensity laser spike, arrives to the core. This shock crosses the core, rebounds at the target center and increases the central pressure to the ignition conditions. In this work we consider this latter phase by using the Guderley self-similar solution for converging flows. Our model accounts for the fusion reaction energy deposition, thermal and radiation losses thus describing the basic physics of hot spot ignition. The ignition criterion derived from the analytical model is successfully compared with full scale hydrodynamic simulations. (authors)

Quantitative understanding of Forbush decrease drivers based on shock-only and CME-only models using global signature of February 14, 1978 event

Energy Technology Data Exchange (ETDEWEB)

Raghav, Anil; Lotekar, Ajay [University Department of Physics, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai-400098 (India); Bhaskar, Ankush; Vichare, Geeta; Yadav, Virendra, E-mail: raghavanil1984@gmail.com, E-mail: ankushbhaskar@gmail.com, E-mail: ablotekar@gmail.com, E-mail: vicharegeeta@gmail.com, E-mail: virendray.iig@gmail.com [Indian Institute of Geomagnetism, Plot 5, Sector 18, New Panvel, Navi Mumbai-410218 (India)

2014-10-01

We have studied the Forbush decrease (FD) event that occurred on February 14, 1978 using 43 neutron monitor observatories to understand the global signature of FD. We have studied rigidity dependence of shock amplitude and total FD amplitude. We have found almost the same power law index for both shock phase amplitude and total FD amplitude. Local time variation of shock phase amplitude and maximum depression time of FD have been investigated which indicate possible effect of shock/CME orientation. We have analyzed rigidity dependence of time constants of two phase recovery. Time constants of slow component of recovery phase show rigidity dependence and imply possible effect of diffusion. Solar wind speed was observed to be well correlated with slow component of FD recovery phase. This indicates solar wind speed as possible driver of recovery phase. To investigate the contribution of interplanetary drivers, shock and CME in FD, we have used shock-only and CME-only models. We have applied these models separately to shock phase and main phase amplitudes respectively. This confirms presently accepted physical scenario that the first step of FD is due to propagating shock barrier and second step is due to flux rope of CME/magnetic cloud.

Quantitative understanding of Forbush decrease drivers based on shock-only and CME-only models using global signature of February 14, 1978 event

International Nuclear Information System (INIS)

Raghav, Anil; Lotekar, Ajay; Bhaskar, Ankush; Vichare, Geeta; Yadav, Virendra

2014-01-01

We have studied the Forbush decrease (FD) event that occurred on February 14, 1978 using 43 neutron monitor observatories to understand the global signature of FD. We have studied rigidity dependence of shock amplitude and total FD amplitude. We have found almost the same power law index for both shock phase amplitude and total FD amplitude. Local time variation of shock phase amplitude and maximum depression time of FD have been investigated which indicate possible effect of shock/CME orientation. We have analyzed rigidity dependence of time constants of two phase recovery. Time constants of slow component of recovery phase show rigidity dependence and imply possible effect of diffusion. Solar wind speed was observed to be well correlated with slow component of FD recovery phase. This indicates solar wind speed as possible driver of recovery phase. To investigate the contribution of interplanetary drivers, shock and CME in FD, we have used shock-only and CME-only models. We have applied these models separately to shock phase and main phase amplitudes respectively. This confirms presently accepted physical scenario that the first step of FD is due to propagating shock barrier and second step is due to flux rope of CME/magnetic cloud

Astrophysically relevant radiatively cooled hypersonic bow shocks in nested wire arrays

Science.gov (United States)

Ampleford, David

2009-11-01

We have performed laboratory experiments which introduce obstructions into hypersonic plasma flows to study the formation of shocks. Astrophysical observations have demonstrated many examples of equivalent radiatively cooled bow shocks, for example the head of protostellar jets or supernova remnants passing through the interstellar medium or between discrete clumps in jets. Wire array z-pinches allow us to study quasi-planar radiatively cooled flows in the laboratory. The early stage of a wire array z-pinch implosion consists of a steady flow of the wire material towards the axis. Given a high rate of radiative cooling, these flows reach high sonic- Mach numbers, typically up to 5. The 2D nature of this configuration allows the insertion of obstacles into the flow, such as a concentric ``inner'' wire array, as has previously been studied for ICF research. Here we study the application of such a nested array to laboratory astrophysics where the inner wires act as obstructions perpendicular to the flow, and induce bow shocks. By varying the wire array material (W/Al), the significance of radiative cooling on these shocks can be controlled, and is shown to change the shock opening angle. As multiple obstructions are present, the experiments show the interaction of multiple bow shocks. It is also possible to introduce a magnetic field around the static object, increasing the opening angle of the shocks. Further experiments can be designed to control the flow density, magnetic field structure and obstruction locations. In collaboration with: S.V. Lebedev, M.E. Cuneo, C.A. Jennings, S.N. Bland, J.P. Chittenden, A. Ciardi, G.N. Hall, S.C. Bott, M. Sherlock, A. Frank, E. Blackman

MEASUREMENTS OF SHOCK WAVE FORCE IN SHOCK TUBE WITH INDIRECT METHODS

Directory of Open Access Journals (Sweden)

Mario Dobrilović

2005-12-01

Full Text Available Tests have been conducted at the “Laboratory for testing of civil explosives, detonators, electrical detonators and pyrotechnical materials”, Department for mining and geotechnics of the Faculty of mining, geology and petroleum engineering, University of Zagreb with the purpose of designing a detonator that would unite advantages of a non-electric system and the precision in regulation of time delay in electronic initiation system. Sum of energy released by the wave force in shock tube is a pre-condition for operation of the new detonator, and measurement of wave force is the first step in determining the sum of energy. The sum of energy is measured indirectly, based on two principles: movement sensors and strain.

Kidney damage in extracorporeal shock wave lithotripsy: a numerical approach for different shock profiles.

Science.gov (United States)

Weinberg, Kerstin; Ortiz, Michael

2009-08-01

In shock-wave lithotripsy--a medical procedure to fragment kidney stones--the patient is subjected to hypersonic waves focused at the kidney stone. Although this procedure is widely applied, the physics behind this medical treatment, in particular the question of how the injuries to the surrounding kidney tissue arise, is still under investigation. To contribute to the solution of this problem, two- and three-dimensional numerical simulations of a human kidney under shock-wave loading are presented. For this purpose a constitutive model of the bio-mechanical system kidney is introduced, which is able to map large visco-elastic deformations and, in particular, material damage. The specific phenomena of cavitation induced oscillating bubbles is modeled here as an evolution of spherical pores within the soft kidney tissue. By means of large scale finite element simulations, we study the shock-wave propagation into the kidney tissue, adapt unknown material parameters and analyze the resulting stress states. The simulations predict localized damage in the human kidney in the same regions as observed in animal experiments. Furthermore, the numerical results suggest that in first instance the pressure amplitude of the shock wave impulse (and not so much its exact time-pressure profile) is responsible for damaging the kidney tissue.

Laser-plasma interaction physics for shock ignition

Directory of Open Access Journals (Sweden)

Goyon C.

2013-11-01

Full Text Available In the shock ignition scheme, the ICF target is first compressed with a long (nanosecond pulse before creating a convergent shock with a short (∼100 ps pulse to ignite thermonuclear reactions. This short pulse is typically (∼2.1015–1016 W/cm2 above LPI (Laser Plasma Instabilities thresholds. The plasma is in a regime where the electron temperature is expected to be very high (2–4 keV and the laser coupling to the plasma is not well understood. Emulating LPI in the corona requires large and hot plasmas produced by high-energy lasers. We conducted experiments on the LIL (Ligne d'Integration Laser, 10 kJ at 3ω and the LULI2000 (0.4 kJ at 2ω facilities, to approach these conditions and study absorption and LPI produced by a high intensity beam in preformed plasmas. After introducing the main risks associated with the short pulse propagation, we present the latest experiment we conducted on LPI in relevant conditions for shock ignition.

High-order shock-fitted detonation propagation in high explosives

Science.gov (United States)

Romick, Christopher M.; Aslam, Tariq D.

2017-03-01

A highly accurate numerical shock and material interface fitting scheme composed of fifth-order spatial and third- or fifth-order temporal discretizations is applied to the two-dimensional reactive Euler equations in both slab and axisymmetric geometries. High rates of convergence are not typically possible with shock-capturing methods as the Taylor series analysis breaks down in the vicinity of discontinuities. Furthermore, for typical high explosive (HE) simulations, the effects of material interfaces at the charge boundary can also cause significant computational errors. Fitting a computational boundary to both the shock front and material interface (i.e. streamline) alleviates the computational errors associated with captured shocks and thus opens up the possibility of high rates of convergence for multi-dimensional shock and detonation flows. Several verification tests, including a Sedov blast wave, a Zel'dovich-von Neumann-Döring (ZND) detonation wave, and Taylor-Maccoll supersonic flow over a cone, are utilized to demonstrate high rates of convergence to nontrivial shock and reaction flows. Comparisons to previously published shock-capturing multi-dimensional detonations in a polytropic fluid with a constant adiabatic exponent (PF-CAE) are made, demonstrating significantly lower computational error for the present shock and material interface fitting method. For an error on the order of 10 m /s, which is similar to that observed in experiments, shock-fitting offers a computational savings on the order of 1000. In addition, the behavior of the detonation phase speed is examined for several slab widths to evaluate the detonation performance of PBX 9501 while utilizing the Wescott-Stewart-Davis (WSD) model, which is commonly used in HE modeling. It is found that the thickness effect curve resulting from this equation of state and reaction model using published values is dramatically more steep than observed in recent experiments. Utilizing the present fitting

Microsoft Office Word 2007 step by step

CERN Document Server

Cox, Joyce

2007-01-01

Experience learning made easy-and quickly teach yourself how to create impressive documents with Word 2007. With Step By Step, you set the pace-building and practicing the skills you need, just when you need them!Apply styles and themes to your document for a polished lookAdd graphics and text effects-and see a live previewOrganize information with new SmartArt diagrams and chartsInsert references, footnotes, indexes, a table of contentsSend documents for review and manage revisionsTurn your ideas into blogs, Web pages, and moreYour all-in-one learning experience includes:Files for building sk

Laminar-turbulent transition tripped by step on transonic compressor profile

Science.gov (United States)

Flaszynski, Pawel; Doerffer, Piotr; Szwaba, Ryszard; Piotrowicz, Michal; Kaczynski, Piotr

2018-02-01

The shock wave boundary layer interaction on the suction side of transonic compressor blade is one of the main objectives of TFAST project (Transition Location Effect on Shock Wave Boundary Layer Interaction). The experimental and numerical results for the flow structure investigations are shown for the flow conditions as the existing ones on the suction side of the compressor profile. The two cases are investigated: without and with boundary layer tripping device. In the first case, boundary layer is laminar up to the shock wave, while in the second case the boundary layer is tripped by the step. Numerical results carried out by means of Fine/Turbo Numeca with Explicit Algebraic Reynolds Stress Model including transition modeling are compared with schlieren, Temperature Sensitive Paint and wake measurements. Boundary layer transition location is detected by Temperature Sensitive Paint.

Shock Initiation of Damaged Explosives

Energy Technology Data Exchange (ETDEWEB)

Chidester, S K; Vandersall, K S; Tarver, C M

2009-10-22

Explosive and propellant charges are subjected to various mechanical and thermal insults that can increase their sensitivity over the course of their lifetimes. To quantify this effect, shock initiation experiments were performed on mechanically and thermally damaged LX-04 (85% HMX, 15% Viton by weight) and PBX 9502 (95% TATB, 5% Kel-F by weight) to obtain in-situ manganin pressure gauge data and run distances to detonation at various shock pressures. We report the behavior of the HMX-based explosive LX-04 that was damaged mechanically by applying a compressive load of 600 psi for 20,000 cycles, thus creating many small narrow cracks, or by cutting wedge shaped parts that were then loosely reassembled, thus creating a few large cracks. The thermally damaged LX-04 charges were heated to 190 C for long enough for the beta to delta solid - solid phase transition to occur, and then cooled to ambient temperature. Mechanically damaged LX-04 exhibited only slightly increased shock sensitivity, while thermally damaged LX-04 was much more shock sensitive. Similarly, the insensitive explosive PBX 9502 was mechanically damaged using the same two techniques. Since PBX 9502 does not undergo a solid - solid phase transition but does undergo irreversible or 'rachet' growth when thermally cycled, thermal damage to PBX 9502 was induced by this procedure. As for LX-04, the thermally damaged PBX 9502 demonstrated a greater shock sensitivity than mechanically damaged PBX 9502. The Ignition and Growth reactive flow model calculated the increased sensitivities by igniting more damaged LX-04 and PBX 9502 near the shock front based on the measured densities (porosities) of the damaged charges.

Shock compression and quasielastic release in tantalum

International Nuclear Information System (INIS)

Johnson, J.N.; Hixson, R.S.; Tonks, D.L.; Gray, G.T. III

1994-01-01

Previous studies of quasielastic release in shock-loaded FCC metals have shown a strong influence of the defect state on the leading edge, or first observable arrival, of the release wave. This is due to the large density of pinned dislocation segments behind the shock front, their relatively large pinning separation, and a very short response time as determined by the drag coefficient in the shock-compressed state. This effect is entirely equivalent to problems associated with elastic moduli determination using ultrasonic methods. This is particularly true for FCC metals, which have an especially low Peierls stress, or inherent lattice resistance, that has little influence in pinning dislocation segments and inhibiting anelastic deformation. BCC metals, on the other hand, have a large Peierls stress that essentially holds dislocation segments in place at low net applied shear stresses and thus allows fully elastic deformation to occur in the complete absence of anelastic behavior. Shock-compression and release experiments have been performed on tantalum (BCC), with the observation that the leading release disturbance is indeed elastic. This conclusion is established by examination of experimental VISAR records taken at the tantalum/sapphire (window) interface in a symmetric-impact experiment which subjects the sample to a peak longitudinal stress of approximately 7.3 GPa, in comparison with characteristic code calculations. copyright 1994 American Institute of Physics

Evolution of elastic precursor and plastic shock wave in copper via molecular dynamics simulations

International Nuclear Information System (INIS)

Perriot, Romain; Zhakhovsky, Vasily V; Oleynik, Ivan I; Inogamov, Nail A

2014-01-01

Large-scale molecular dynamics (MD) simulations are performed to investigate shock propagation in single crystal copper. It is shown that the P-V plastic Hugoniot is unique regardless of the sample's orientation, its microstructure, or its length. However, the P-V pathway to the final state is not, and depends on many factors. Specifically, it is shown that the pressure in the elastic precursor (the Hugoniot elastic limit (HEL)) decreases as the shock wave propagates in a micron-sized sample. The attenuation of the HEL in sufficiently-long samples is the main source of disagreement between previous MD simulations and experiment: while single crystal experiments showed that the plastic shock speed is orientation-independent, the simulated plastic shock speed was observed to be orientation-dependent in relatively short single-crystal samples. Such orientation dependence gradually disappears for relatively long, micrometer-sized, samples for all three low-index crystallographic directions (100), (110), and (111), and the plastic shock velocities for all three directions approach the one measured in experiment. The MD simulations also demonstrate the existence of subsonic plastic shock waves generated by relatively weak supporting pressures.

Toxic shock syndrome

Science.gov (United States)

Staphylococcal toxic shock syndrome; Toxic shock-like syndrome; TSLS ... Toxic shock syndrome is caused by a toxin produced by some types of staphylococcus bacteria. A similar problem, called toxic shock- ...

Analysis of compaction shock interactions during DDT of low density HMX

Science.gov (United States)

Rao, Pratap T.; Gonthier, Keith A.

2017-01-01

Deflagration-to-Detonation Transition (DDT) in confined, low density granular HMX occurs by a complex mechanism that involves compaction shock interactions within the material. Piston driven DDT experiments indicate that detonation is abruptly triggered by the interaction of a strong combustion-supported secondary shock and a piston-supported primary (input) shock, where the nature of the interaction depends on initial packing density and primary shock strength. These interactions influence transition by affecting dissipative heating within the microstructure during pore collapse. Inert meso-scale simulations of successive shock loading of low density HMX are performed to examine how dissipation and hot-spot formation are affected by the initial density, and the primary and secondary shock strengths. This information is used to formulate an ignition and burn model for low density HMX that accounts for the effect of shock densensitization on burn. Preliminary DDT predictions are presented that illustrate how primary shock strength affects the transition mechanism.

DESTRUCTION OF INTERSTELLAR DUST IN EVOLVING SUPERNOVA REMNANT SHOCK WAVES

International Nuclear Information System (INIS)

Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.

2015-01-01

Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however, that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al., we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities ≳200 km s −1 for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of ∼2 compared to those of Jones et al., who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of ∼3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of ∼2–3 Gyr. These increases, while not able to resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step toward understanding the origin and evolution of dust in the ISM

ION ACCELERATION AT THE QUASI-PARALLEL BOW SHOCK: DECODING THE SIGNATURE OF INJECTION

Energy Technology Data Exchange (ETDEWEB)

Sundberg, Torbjörn; Haynes, Christopher T.; Burgess, D. [School of Physics and Astronomy, Queen Mary University of London, London, E1 4NS (United Kingdom); Mazelle, Christian X. [IRAP, Université Paul Sabatier Toulouse III-CNRS, 31028 Toulouse Cedex 4 (France)

2016-03-20

Collisionless shocks are efficient particle accelerators. At Earth, ions with energies exceeding 100 keV are seen upstream of the bow shock when the magnetic geometry is quasi-parallel, and large-scale supernova remnant shocks can accelerate ions into cosmic-ray energies. This energization is attributed to diffusive shock acceleration; however, for this process to become active, the ions must first be sufficiently energized. How and where this initial acceleration takes place has been one of the key unresolved issues in shock acceleration theory. Using Cluster spacecraft observations, we study the signatures of ion reflection events in the turbulent transition layer upstream of the terrestrial bow shock, and with the support of a hybrid simulation of the shock, we show that these reflection signatures are characteristic of the first step in the ion injection process. These reflection events develop in particular in the region where the trailing edge of large-amplitude upstream waves intercept the local shock ramp and the upstream magnetic field changes from quasi-perpendicular to quasi-parallel. The dispersed ion velocity signature observed can be attributed to a rapid succession of ion reflections at this wave boundary. After the ions’ initial interaction with the shock, they flow upstream along the quasi-parallel magnetic field. Each subsequent wavefront in the upstream region will sweep the ions back toward the shock, where they gain energy with each transition between the upstream and the shock wave frames. Within three to five gyroperiods, some ions have gained enough parallel velocity to escape upstream, thus completing the injection process.

Short pulse duration shock initiation experiments plus ignition and growth modeling on Composition B

International Nuclear Information System (INIS)

May, Chadd M; Tarver, Craig M

2014-01-01

Composition B (63% RDX, 36% TNT, 1% wax) is still a widely used energetic material whose shock initiation characteristics are necessary to understand. It is now possible to shock initiate Composition B and other secondary explosives at diameters well below their characteristic failure diameters for unconfined self-sustaining detonation. This is done using very high velocity, very thin, small diameter flyer plates accelerated by electric or laser power sources. Recently experimental detonation versus failure to detonate threshold flyer velocity curves for Composition B using several Kapton TM flyer thicknesses and diameters were measured. Flyer plates with diameters of 2 mm successfully detonated Composition B, which has a nominal failure diameter of 4.3 mm. The shock pressures required for these initiations are greater than the Chapman-Jouguet (C-J) pressure in self-sustaining Composition B detonation waves. The initiation process is two-dimensional, because both rear and side rarefactions can affect the shocked Composition B reaction rates. The Ignition and Growth reactive flow model for Composition B is extended to yield accurate simulations of this new threshold velocity data for various flyer thicknesses.

Bifurcation parameters of a reflected shock wave in cylindrical channels of different roughnesses

Science.gov (United States)

Penyazkov, O.; Skilandz, A.

2018-03-01

To investigate the effect of bifurcation on the induction time in cylindrical shock tubes used for chemical kinetic experiments, one should know the parameters of the bifurcation structure of a reflected shock wave. The dynamics and parameters of the shock wave bifurcation, which are caused by reflected shock wave-boundary layer interactions, are studied experimentally in argon, in air, and in a hydrogen-nitrogen mixture for Mach numbers M = 1.3-3.5 in a 76-mm-diameter shock tube without any ramp. Measurements were taken at a constant gas density behind the reflected shock wave. Over a wide range of experimental conditions, we studied the axial projection of the oblique shock wave and the pressure distribution in the vicinity of the triple Mach configuration at 50, 150, and 250 mm from the endwall, using side-wall schlieren and pressure measurements. Experiments on a polished shock tube and a shock tube with a surface roughness of 20 {μ }m Ra were carried out. The surface roughness was used for initiating small-scale turbulence in the boundary layer behind the incident shock wave. The effect of small-scale turbulence on the homogenization of the transition zone from the laminar to turbulent boundary layer along the shock tube perimeter was assessed, assuming its influence on a subsequent stabilization of the bifurcation structure size versus incident shock wave Mach number, as well as local flow parameters behind the reflected shock wave. The influence of surface roughness on the bifurcation development and pressure fluctuations near the wall, as well as on the Mach number, at which the bifurcation first develops, was analyzed. It was found that even small additional surface roughness can lead to an overshoot in pressure growth by a factor of two, but it can stabilize the bifurcation structure along the shock tube perimeter.

Experimental Study on Peak Pressure of Shock Waves in Quasi-Shallow Water

Directory of Open Access Journals (Sweden)

Zhenxiong Wang

2015-01-01

Full Text Available Based on the similarity laws of the explosion, this research develops similarity requirements of the small-scale experiments of underwater explosions and establishes a regression model for peak pressure of underwater shock waves under experimental condition. Small-scale experiments are carried out with two types of media at the bottom of the water and for different water depths. The peak pressure of underwater shock waves at different measuring points is acquired. A formula consistent with the similarity law of explosions is obtained and an analysis of the regression precision of the formula confirms its accuracy. Significance experiment indicates that the influence of distance between measuring points and charge on peak pressure of underwater shock wave is the greatest and that of water depth is the least within the range of geometric parameters. An analysis of data from experiments with different media at the bottom of the water reveals an influence on the peak pressure, as the peak pressure of a shock wave in a body of water with a bottom soft mud and rocks is about 1.33 times that of the case where the bottom material is only soft mud.

Coronal mass ejection shock fronts containing the two types of intermediate shocks

International Nuclear Information System (INIS)

Steinolfson, R.S.; Hundhausen, A.J.

1990-01-01

Numerical solutions of the time-dependent, magnetohydrodynamic (MHD) equations in two dimensions are used to demonstrate the formation of both types of intermediate shocks in a single shock front for physical conditions that are an idealization of those expected to occur in some observed coronal mass ejections. The key to producing such a shock configuration in the simulations is the use of an initial atmosphere containing a magnetic field representative of that in a coronal streamer with open field lines overlying a region of closed field lines. Previous attempts using just open field lines (perpendicular to the surface) produced shock configurations containing just one of the two intermediate shock types. A schematic of such a shock front containing both intermediate shock types has been constructed previously based solely on the known properties of MHD shocks from the Rankine-Hugoniot equations and specific requirements placed on the shock solution at points along the front where the shock normal and upstream magnetic field are aligned. The shock front also contains, at various locations along the front, a hydrodynamic (nonmagnetic) shock, a switch-on shock, and a fast shock in addition to the intermediate shocks. This particular configuration occurs when the shock front speed exceeds the upstream (preshock) intermediate wave speed but is less than a critical speed defined in the paper (equation 1) along at least some portion of the shock front. A distinctive feature of the front is that it is concave upward (away from the surface) near the region where the field in the preshock plasma is normal to the front of near the central portion of the shock front

Shock-induced luminescence from Z-cut lithium niobate

International Nuclear Information System (INIS)

Brannon, P.J.; Morris, R.W.; Asay, J.R.

1985-01-01

Shock-induced luminescence from lithium niobate has been studied in the stress range 1.6--21.0 GPa. Both fast-framing photography and five-channel optical pyrometry were used to observe the luminescence. The framing photography showed that the emission pattern is heterogeneous for stresses just above the dynamic yield point. A further increase of the stress resulted in a pattern which was essentially homogeneous to within the experimental spatial resolution of about 30 μm. Narrowband filters and photomultiplier tubes were used in the optical pyrometry experiments. A broadband spectrum with a peak near 700 nm was observed. A plot of the energy dissipated by the shock versus shock stress correlates very well with a plot of the 700-nm intensity versus shock stress. The mechanism for light emission in lithium niobate appears to be closely related to the dynamic yielding process

Microsoft® Office Access™ 2007 Step by Step

CERN Document Server

Lambert, Steve; Lambert, Joan

2009-01-01

Experience learning made easy-and quickly teach yourself how to build database solutions with Access 2007. With Step By Step, you set the pace-building and practicing the skills you need, just when you need them! Build databases from scratch or from templatesExchange data with other databases and Office documentsCreate forms to simplify data entryUse filters and queries to find and analyze informationDesign rich reports that help make your data meaningfulHelp prevent data corruption and unauthorized access Your all-in-one learning experience includes: Files for building skills and practic

Oxygen radicals in experimental shock: effects of spin-trapping nitrones in ameliorating shock pathophysiology (see comments)

Energy Technology Data Exchange (ETDEWEB)

Novelli, G.P. (Institute of Anesthesiology and Intensive Care, University of Florence, Careggi Hospital, (Italy))

1992-04-01

Circulatory shock is accepted as a consequence of an acute oxygen radical overgeneration. Spin-trapping nitrones inactivate free radicals by forming relatively stable adducts. Three spin-trapping nitrones (N-tert-phenyl-butyl-nitrone; alpha-4-pyridyl-oxide-N-tert-butyl-nitrone; 5-5,dimethyl,1,pyrroline-N-oxide) were tested regarding their role in the pathophysiology and evolution of circulatory shock in rats. A prospective, randomized, controlled trial of spin-trapping nitrones in rats experiencing three different models of circulatory shock was designed. In the first group, endotoxic, traumatic, and mesenteric artery occlusion shock (all 100% lethal in control experiments) was prevented by the ip administration of N-tert-phenyl-butyl-nitrone (150 mg/kg); alpha-4-pyridyl-oxide-N-tert-butyl-nitrone (100 mg/kg); or 5-5,dimethyl,1,pyrroline-N-oxide (100 mg/kg). However, the evolution of shock was unaffected by the same compounds when all three nitrones had been previously inactivated by exposure to light and air. In the second group, microcirculatory derangements that were provoked by endotoxin and were observed in the mesocecum of rats were completely prevented by pretreatment with either peritoneal administration of each of the three nitrones or by their topical application to the microscopic field. While the rats survived after systemic treatment, those rats receiving topical nitrones died from endotoxic shock. In the third group, cell-membrane stiffness (a sign of peroxidative damage) was measured by spin-probes and electron-spin resonance in mitochondrial and microsomal membranes. Cell membranes obtained from shocked rats were more rigid than those membranes of controls. However, the membranes obtained from rats that were submitted to trauma or endotoxin after pretreatment with N-tert-phenyl-butyl-nitrone had normal stiffness.

Shock formation within sonoluminescence bubbles

International Nuclear Information System (INIS)

Vuong, V.Q.; Szeri, A.J.; Young, D.A.

1999-01-01

A strong case has been made by several authors that sharp, spherically symmetric shocks converging on the center of a spherical bubble driven by a strong acoustic field give rise to rapid compression and heating that produces the brief flash of light known as sonoluminescence. The formation of such shocks is considered. It is found that, although at the main collapse the bubble wall does indeed launch an inwardly-traveling compression wave, and although the subsequent reflection of the wave at the bubble center produces a very rapid temperature peak, the wave is prevented from steepening into a sharp shock by an adverse gradient in the sound speed caused by heat transfer. It is shown that the mathematical characteristics of the flow can be prevented from accumulating into a shock front by this adverse sound speed gradient. A range of results is presented for a variety of bubble ambient radii and sound field amplitudes suggested by experiments. The time scale of the peak temperature in the bubble is set by the dynamics of the compression wave: this is typically in the range 100 - 300 ps (FWHM) in concert with recent measurements of the sonoluminescence pulse width. copyright 1999 American Institute of Physics

Physics of IED blast shock tube simulations for mTBI research

NARCIS (Netherlands)

Mediavilla Varas, J.; Philippens, M.M.G.M.; Meijer, S.R.; Berg, A.C. van den; Sibma, P.C.; Bree, J.L.M.J. van; Vries, D.V.W.M. de

2011-01-01

Shock tube experiments and simulations are conducted with a spherical gelatin filled skull- brain surrogate, in order to study the mechanisms leading to blast induced mild traumatic brain injury. A shock tube including sensor system is optimized to simulate realistic impro-vised explosive device

Do dividend shocks affect excess returns? An experimental study

Directory of Open Access Journals (Sweden)

Draganac Dragana

2017-01-01

Full Text Available The dividend announcement of a company is an informational event that can cause underreaction, momentum, overreaction, post-dividend announcement drift, and mean reversion. It is the uncertainty surrounding dividend announcements that leads to such behavioural phenomena. Most authors consider that underreaction occurs after dividend shocks because new information about the dividend is being slowly and gradually built into the stock price. The effect of dividend shocks is often reflected in excess returns, which can last up to one year after the shock. The experiment described in this paper tests whether statistically significant excess returns are realized after a shock dividend announcement. Participants trade with the stocks of two companies, which only differ by dividend-generating stochastic process. The dividend process of Company 2 is a Merton-style jump-diffusion process (consisting of two parts: Brownian motion and Poisson jump, while the dividend process of Company 1 contains only the Brownian motion component. Statistically significant excess returns are expected when trading with Company 2 stocks. An autoregressive model is applied in order to test this hypothesis. The conclusion is that a dividend shock is followed by statistically significant excess returns in 20 of the 22 experiments, which implies that markets are inefficient after sudden and large changes in dividends. Underreaction and discount rate effects are identified.

demystifying the shock of shocking

African Journals Online (AJOL)

(with a pulse), atrial fibrillation and atrial flutter. The energy dose in cardioversion is less (0.5. - 2 J/kg) than in defibrillation (2 - 4 J/kg). In cardioversion the shock is discharged synchronously with the native R wave of the patient. Without synchronisation,. VF can be induced if a shock is delivered during the refractory period ...

Shock absorbing structure

International Nuclear Information System (INIS)

Kojima, Naoki; Matsushita, Kazuo.

1992-01-01

Small pieces of shock absorbers are filled in a space of a shock absorbing vessel which is divided into a plurality of sections by partitioning members. These sections function to prevent excess deformation or replacement of the fillers upon occurrence of falling accident. Since the shock absorbing small pieces in the shock absorbing vessel are filled irregularly, shock absorbing characteristics such as compression strength is not varied depending on the direction, but they exhibit excellent shock absorbing performance. They surely absorb shocks exerted on a transportation vessel upon falling or the like. If existing artificial fillers such as pole rings made of metal or ceramic and cut pieces such as alumium extrusion molding products are used as the shock absorbing pieces, they have excellent fire-proofness and cold resistance since the small pieces are inflammable and do not contain water. (T.M.)

Laser driven single shock compression of fluid deuterium from 45 to 220 GPa

Energy Technology Data Exchange (ETDEWEB)

Hicks, D; Boehly, T; Celliers, P; Eggert, J; Moon, S; Meyerhofer, D; Collins, G

2008-03-23

The compression {eta} of liquid deuterium between 45 and 220 GPa under laser-driven shock loading has been measured using impedance matching to an aluminum (Al) standard. An Al impedance match model derived from a best fit to absolute Hugoniot data has been used to quantify and minimize the systematic errors caused by uncertainties in the high-pressure Al equation of state. In deuterium below 100 GPa results show that {eta} {approx_equal} 4.2, in agreement with previous impedance match data from magnetically-driven flyer and convergent-explosive shock wave experiments; between 100 and 220 GPa {eta} reaches a maximum of {approx}5.0, less than the 6-fold compression observed on the earliest laser-shock experiments but greater than expected from simple extrapolations of lower pressure data. Previous laser-driven double-shock results are found to be in good agreement with these single-shock measurements over the entire range under study. Both sets of laser-shock data indicate that deuterium undergoes an abrupt increase in compression at around 110 GPa.

Ionization relaxation in shock-heated krypton-argon mixtures

International Nuclear Information System (INIS)

Ezumi, Hiromichi; Kawamura, Masahiko; Yokota, Toshiaki.

1977-01-01

The ionization relaxation processes behind shock waves in pure krypton and krypton-argon mixtures have been investigated using a Mach-Zehnder interferometer technique. The incident shock velocity was fixed in the neighborhood of Us=2800 m/sec, and the initial pressure was fixed at 0.95 Torr. The experimental results were compared with theoretical values based on the two-step collisional ionization model taking into account of the wall boundary-layer effect. The slope constants of excitation cross section against relative kinetic energy between krypton atom-atom collisions, krypton atom-electron collisions, and krypton-argon atom-atom collisions were determined to be 4.2 x 10 -19 cm 2 /eV, 1.2 x 10 -17 cm 2 /eV, and 4.2 x 10 -19 cm 2 /eV, respectively. (auth.)

Shock-induced nanobubble collapse and its applications

Science.gov (United States)

Vedadi, Mohammad Hossein

The shock-induced collapse of nanobubbles in water is investigated using molecular dynamics simulations based on a reactive force field. Monitoring the collapse of a cavitation nanobubble, we observe a focused nanojet at the onset of bubble shrinkage and a water hammer shock wave upon bubble collapse. The nanojet length scales linearly with the nanobubble radius, as observed in experiments on micron-to-millimeter size bubbles. The shock induces dramatic structural changes, including an ice-VII-like structural motif at a particle velocity of approximately 1 km/s. The incipient ice VII formation and the calculated Hugoniot curve are in good agreement with experimental results. Moreover, a substantial number of positive and negative ions appear when the nanojet hits the distal side of the nanobubble and the water hammer shock forms. Furthermore, two promising applications of shock-induced nanobubble collapse have been explored. Our simulations of poration in lipid bilayers due to shock-induced collapse of nanobubbles reveal penetration of nanojets into lipid bilayers. The nanojet impact generates shear flow of water on bilayer leaflets and pressure gradients across them, which transiently enhance the bilayer permeability by creating nanopores through which water molecules translocate across the bilayer. The effects of nanobubble size and temperature on the porosity of lipid bilayers are examined. Finally, the shock-induced collapse of CO2-filled nanobubbles in water is investigated. The energetic nanojet and high-pressure water hammer shock formed during and after collapse of the nanobubble trigger mechano-chemical H2O-CO2 reactions, some of which lead to splitting of water molecules. The dominant pathways through which splitting of water molecules occur are identified.

Thermal shock behaviour of different tungsten grades under varying conditions

Energy Technology Data Exchange (ETDEWEB)

Wirtz, Oliver Marius

2012-07-19

Thermonuclear fusion power plants are a promising option to ensure the energy supply for future generations, but in many fields of research enormous challenges have to be faced. A major step on the way to the prototype fusion reactor DEMO will be ITER which is build in Cadarache, southern France. One of the most critical issues is the field of in-vessel materials and components, in particular the plasma facing materials (PFM). PFMs that will be used in a device like ITER have to withstand severe environmental conditions in terms of steady state and transient thermal loads as well as high particle fluxes such as hydrogen, helium and neutrons. Candidate wall materials are beryllium, tungsten and carbon based materials like CFC (carbon fibre composite). Tungsten is the most promising material for an application in the divertor region with very severe loading conditions and it will most probably also be used as PFM for DEMO. Hence, this work focuses on the investigation of the thermal shock response of different tungsten grades in order to understand the damage mechanisms and to identify material parameters which influence this behaviour under ITER and DEMO relevant operation conditions. Therefore the microstructure and the mechanical and thermal properties of five industrially manufactured tungsten grades were characterised. All five tungsten grades were exposed to transient thermal events with very high power densities of up to 1.27 GWm{sup -2} at varying base temperatures between RT and 600 C in the electron beam device JUDITH 1. The pulse numbers were limited to a maximum of 1000 in order to avoid immoderate workload on the test facility and to have enough time to cover a wide range of loading conditions. The results of this damage mapping enable to define different damage and cracking thresholds for the investigated tungsten grades and to identify certain material parameters which influence the location of these thresholds and the distinction of the induced

Thermal shock behaviour of different tungsten grades under varying conditions

International Nuclear Information System (INIS)

Wirtz, Oliver Marius

2012-01-01

Thermonuclear fusion power plants are a promising option to ensure the energy supply for future generations, but in many fields of research enormous challenges have to be faced. A major step on the way to the prototype fusion reactor DEMO will be ITER which is build in Cadarache, southern France. One of the most critical issues is the field of in-vessel materials and components, in particular the plasma facing materials (PFM). PFMs that will be used in a device like ITER have to withstand severe environmental conditions in terms of steady state and transient thermal loads as well as high particle fluxes such as hydrogen, helium and neutrons. Candidate wall materials are beryllium, tungsten and carbon based materials like CFC (carbon fibre composite). Tungsten is the most promising material for an application in the divertor region with very severe loading conditions and it will most probably also be used as PFM for DEMO. Hence, this work focuses on the investigation of the thermal shock response of different tungsten grades in order to understand the damage mechanisms and to identify material parameters which influence this behaviour under ITER and DEMO relevant operation conditions. Therefore the microstructure and the mechanical and thermal properties of five industrially manufactured tungsten grades were characterised. All five tungsten grades were exposed to transient thermal events with very high power densities of up to 1.27 GWm -2 at varying base temperatures between RT and 600 C in the electron beam device JUDITH 1. The pulse numbers were limited to a maximum of 1000 in order to avoid immoderate workload on the test facility and to have enough time to cover a wide range of loading conditions. The results of this damage mapping enable to define different damage and cracking thresholds for the investigated tungsten grades and to identify certain material parameters which influence the location of these thresholds and the distinction of the induced damages

Constrained reaction volume approach for studying chemical kinetics behind reflected shock waves

KAUST Repository

Hanson, Ronald K.

2013-09-01

We report a constrained-reaction-volume strategy for conducting kinetics experiments behind reflected shock waves, achieved in the present work by staged filling in a shock tube. Using hydrogen-oxygen ignition experiments as an example, we demonstrate that this strategy eliminates the possibility of non-localized (remote) ignition in shock tubes. Furthermore, we show that this same strategy can also effectively eliminate or minimize pressure changes due to combustion heat release, thereby enabling quantitative modeling of the kinetics throughout the combustion event using a simple assumption of specified pressure and enthalpy. We measure temperature and OH radical time-histories during ethylene-oxygen combustion behind reflected shock waves in a constrained reaction volume and verify that the results can be accurately modeled using a detailed mechanism and a specified pressure and enthalpy constraint. © 2013 The Combustion Institute.

Bacterial survival following shock compression in the GigaPascal range

Science.gov (United States)

Hazael, Rachael; Fitzmaurice, Brianna C.; Foglia, Fabrizia; Appleby-Thomas, Gareth J.; McMillan, Paul F.

2017-09-01

The possibility that life can exist within previously unconsidered habitats is causing us to expand our understanding of potential planetary biospheres. Significant populations of living organisms have been identified at depths extending up to several km below the Earth's surface; whereas laboratory experiments have shown that microbial species can survive following exposure to GigaPascal (GPa) pressures. Understanding the degree to which simple organisms such as microbes survive such extreme pressurization under static compression conditions is being actively investigated. The survival of bacteria under dynamic shock compression is also of interest. Such studies are being partly driven to test the hypothesis of potential transport of biological organisms between planetary systems. Shock compression is also of interest for the potential modification and sterilization of foodstuffs and agricultural products. Here we report the survival of Shewanella oneidensis bacteria exposed to dynamic (shock) compression. The samples examined included: (a) a "wild type" (WT) strain and (b) a "pressure adapted" (PA) population obtained by culturing survivors from static compression experiments to 750 MPa. Following exposure to peak shock pressures of 1.5 and 2.5 GPa the proportion of survivors was established as the number of colony forming units (CFU) present after recovery to ambient conditions. The data were compared with previous results in which the same bacterial samples were exposed to static pressurization to the same pressures, for 15 minutes each. The results indicate that shock compression leads to survival of a significantly greater proportion of both WT and PA organisms. The significantly shorter duration of the pressure pulse during the shock experiments (2-3 μs) likely contributes to the increased survival of the microbial species. One reason for this can involve the crossover from deformable to rigid solid-like mechanical relaxational behavior that occurs for

Study on Reflected Shock Wave/Boundary Layer Interaction in a Shock Tube

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Wook; Kim, Tae Ho; Kim, Heuy Dong [Andong Nat’l Univ., Andong (Korea, Republic of)

2017-07-15

The interaction between a shock wave and a boundary layer causes boundary layer separation, shock train, and in some cases, strong unsteadiness in the flow field. Such a situation is also observed in a shock tube, where the reflected shock wave interacts with the unsteady boundary layer. However, only a few studies have been conducted to investigate the shock train phenomenon in a shock tube. In the present study, numerical studies were conducted using the two-dimensional axisymmetric domain of a shock tube, and compressible Navier-Stokes equations were solved to clarify the flow characteristics of shock train phenomenon inside a shock tube. A detailed wave diagram was developed based on the present computational results, which were validated with existing experimental data.

The elevated temperature and thermal shock fracture toughnesses of nuclear pressure vessel steel

International Nuclear Information System (INIS)

Hirano, Kazumi; Kobayashi, Hideo; Nakazawa, Hajime; Nara, Atsushi.

1979-01-01

Thermal shock experiments were conducted on nuclear pressure vessel steel A533 Grade B Class 1. Elastic-plastic fracture toughness tests were carried out within the same high temperature range of the thermal shock experiment and the relation between stretched zone width, SZW and J-integral was clarified. An elastic-plastic thermal shock fracture toughness value. J sub(tsc) was evaluated from a critical value of stretched zone width, SZW sub(tsc) at the initiation of thermal shock fracture by using the relation between SZW and J. The J sub(tsc) value was compared with elastic-plastic fracture toughness values, J sub( ic), and the difference between the J sub(tsc) and J sub( ic) values was discussed. The results obtained are summarized as follows; (1) The relation between SZW and J before the initiation of stable crack growth in fracture toughness test at a high temperature can be expressed by the following equation regardless of test temperature, SZW = 95(J/E), where E is Young's modulus. (2) Elevated temperature fracture toughness values ranging from room temperature to 400 0 C are nearly constant regardless of test temperature. It is confirmed that upper shelf fracture toughness exists. (3) Thermal shock fracture toughness is smaller than elevated temperature fracture toughness within the same high temperature range of thermal shock experiment. (author)

Analogy between soap film and gas dynamics. II. Experiments on one-dimensional motion of shock waves in soap films

Energy Technology Data Exchange (ETDEWEB)

Wen, C.Y.; Chang-Jian, S.K.; Chuang, M.C. [Department of Mechanical Engineering, Da-Yeh University, Chang-Hwa (Taiwan)

2003-02-01

This paper presents an experimental investigation of one-dimensional moving shock waves in vertical soap films. The shock waves were generated by bursting the films with a perforating spark. Images of propagating shock waves and small disturbances were recorded using a fast line scan CCD camera. An aureole and a shock wave preceding the rim of the expanding hole were clearly observed. These images are similar to the x-t diagrams in gas dynamics and give the velocities of shock and sound waves. The moving shock waves cause jumps in thickness. The variations of the induced Mach number, M{sub 2} and the ratio of film thickness across the shock wave, {delta}{sub 2}/{delta}{sub 1}, are plotted versus the shock Mach number, M{sub s}. Both results suggest that soap films are analogous to compressible gases with a specific heat ratio of {gamma}{approx_equal}1.0. (orig.)

[Our experience in Fournier's gangrene with severe septic shock].

Science.gov (United States)

Lukász, Péter; Ecsedy, Gábor; Lovay, Zoltán; Nagy, István; Kári, Dániel; Vörös, Attila; Ender, Ferenc

2014-06-01

Fournier's gangrene is a rare, rapidly progressing necrotizing fasciitis, which involves the genital area and perineum, progresses towards the thighs and abdominal wall through fascial plains. In our surgical department we treated seven patients with Fournier's gangrene between 2007 and 2011. Early diagnosis, immediate radical surgical debridement, necrosectomy, appropriate antibiotics and intensive care are all required and necessary for the successful treatment. Despite appropriate therapy, two patients were lost in septic shock.

Highly Resolved Measurements of a Developing Strong Collisional Plasma Shock

Science.gov (United States)

Rinderknecht, Hans G.; Park, H.-S.; Ross, J. S.; Amendt, P. A.; Higginson, D. P.; Wilks, S. C.; Haberberger, D.; Katz, J.; Froula, D. H.; Hoffman, N. M.; Kagan, G.; Keenan, B. D.; Vold, E. L.

2018-03-01

The structure of a strong collisional shock front forming in a plasma is directly probed for the first time in laser-driven gas-jet experiments. Thomson scattering of a 526.5 nm probe beam was used to diagnose temperature and ion velocity distribution in a strong shock (M ˜11 ) propagating through a low-density (ρ ˜0.01 mg /cc ) plasma composed of hydrogen. A forward-streaming population of ions traveling in excess of the shock velocity was observed to heat and slow down on an unmoving, unshocked population of cold protons, until ultimately the populations merge and begin to thermalize. Instabilities are observed during the merging, indicating a uniquely plasma-phase process in shock front formation.

On ion injection at quasiparallel shocks

International Nuclear Information System (INIS)

Scholer, M.; Kucharek, H.; Kato, C.

2002-01-01

A large number of numerical experiments has been performed in order to study the interaction of interstellar pickup protons and helium ions with quasiparallel collisionless shocks. The shocks are modeled by a one-dimensional hybrid simulation method which treats the ions as macroparticles and the electrons as a massless fluid. Solar wind alpha particles and pickup protons are included self-consistently. In addition, the particle splitting method is used for the solar wind ions so that the distribution function can be followed over more than 10 orders of magnitude. A large part of the pickup ion distribution is reflected; the reflection efficiency is very high, and can reach in cases where the pickup ion density is low as much as 50%-60%. The reflection efficiency is almost independent of magnetic field-shock normal angle. This indicates that magnetic mirroring is unimportant and does not lead to larger reflection efficiencies. The reflection efficiency of pickup protons rapidly decreases when the pickup ion density exceeds a few percent of the solar wind density. An addition of 25% pickup protons decreases the reflection coefficient for these ions to ∼10%. This represents the fact that a quasiparallel shock cannot be considered as being uncoupled from the upstream region: at high additions of pickup ions the shock structure is changed in such a way as to reflect less pickup ions. The intensity of diffuse ions upstream of a quasiparallel shock does not depend on the temperature of the core distribution. Within the framework of the present model even solar wind distributions with a hard power law tail do not produce higher intensities of diffuse ions. It is argued that this can be understood by the fact that the intrinsic self-consistency between the processes in the upstream region and at the shock transition determines the injection and reflection properties of the core solar wind distribution

Characteristics of shock propagation in high-strength cement mortar

Science.gov (United States)

Wang, Zhanjiang; Li, Xiaolan; Zhang, Ruoqi

2001-06-01

Planar impact experiments have been performed on high-strength cement mortar to determine characteristics of shock propagation.The experiments were conducted on a light-gas gun,and permanent-magnet particle velocity gages were used to obtain the sand of 0.5 3.5mm size.A bulk density of 2.31g/cm^3,and a compressive and tensile strength of 82MPa and 7.8MPa,respectively,were determined.Three kinds of experimental techniques were used,including the reverse ballistic configuration.These techniques effectively averaged the measured dynamic compression state over a sensibly large volume of the test sample.The impact velocities were controlled over a range of approximately 80m/s to 0.83km/s.Hugoniot equation of state data were obtained for the material over a pressure range of approximately 0.2 2.0GPa,and its nonlinear constitutive relation were analyzed.The experiment results show that,in higher pressure range provided in the experiment,the shock wave in the material splits into two components of an elastic and a plastic,with the Hugoniot elastic limit 0.4 0.5GPa and the precursor velocity about 4.7km/s,and the material presents a very strong nonlinear dynamic response,and its shock amplitude will greatly decrease in propagation.

Dynamics of Laser-Driven Shock Waves in Solid Targets

Science.gov (United States)

Aglitskiy, Y.; Karasik, M.; Velikovich, A. L.; Serlin, V.; Weaver, J.; Schmitt, A. J.; Obenschain, S. P.; Grun, J.; Metzler, N.; Zalesak, S. T.; Gardner, J. H.; Oh, J.; Harding, E. C.

2009-11-01

Accurate shock timing is a key issue of both indirect- and direct-drive laser fusions. The experiments on the Nike laser at NRL presented here were made possible by improvements in the imaging capability of our monochromatic x-ray diagnostics based on Bragg reflection from spherically curved crystals. Side-on imaging implemented on Nike makes it possible to observe dynamics of the shock wave and ablation front in laser-driven solid targets. We can choose to observe a sequence of 2D images or a continuous time evolution of an image resolved in one spatial dimension. A sequence of 300 ps snapshots taken using vanadium backlighter at 5.2 keV reveals propagation of a shock wave in a solid plastic target. The shape of the shock wave reflects the intensity distribution in the Nike beam. The streak records with continuous time resolution show the x-t trajectory of a laser-driven shock wave in a 10% solid density DVB foam.

Collisionless electrostatic shocks

DEFF Research Database (Denmark)

Andersen, H.K.; Andersen, S.A.; Jensen, Vagn Orla

1970-01-01

An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth......An attempt was made in the laboratory to observe the standing collisionless electrostatic shocks in connection with the bow shock of the earth...

Dynamic fragmentation of laser shock-melted tin: experiment and modelling

Energy Technology Data Exchange (ETDEWEB)

De Resseguier, T. [CNRS ENSMA, Lab Combust and Deton, F-86961 Futuroscope (France); Signor, L.; Dragon, A. [CNRS ENSMA, Mecan and Phys Mat Lab, F-86961 Futuroscope (France); Signor, L.; Roy, G. [CEA Valduc, 21 - Is-sur-Tille (France)

2010-07-01

Dynamic fragmentation of shock-loaded metals is an issue of considerable importance for both basic science and a variety of technological applications, such as pyrotechnics or inertial confinement fusion, the latter involving high energy laser irradiation of thin metallic shells. Whereas spall fracture in solid materials has been extensively studied for many years, little data can be found yet about the evolution of this phenomenon after partial or full melting on compression or on release. Here, we present an investigation of dynamic fragmentation in laser shock-melted tin, from the 'micro-spall' process (ejection of a cloud of fine droplets) occurring upon reflection of the compressive pulse from the target free surface, to the late rupture observed in the un-spalled melted layer (leading to the formation of larger spherical fragments). Experimental results consist of time-resolved velocity measurements and post-shock observations of recovered targets and fragments. They provide original information regarding the loss of tensile strength associated with melting, the cavitation mechanism likely to occur in the melted metal, the sizes of the subsequent fragments and their ejection velocities. A theoretical description based on an energetic approach adapted to the case of a liquid metal is implemented as a failure criterion in a one-dimensional hydro-code including a multi-phase equation of state for tin. The resulting predictions of the micro-spall process are compared with experimental data. In particular, the use of a new experimental technique to quantify the fragment size distributions leads to a much better agreement with theory than previously reported. Finally, a complementary approach focused on cavitation is proposed to evaluate the role of this phenomenon in the fragmentation of the melted metal. (authors)

Experiment Study on Elastic Indicator of Thermal Shock Ceramic Materials——Implementation of Students’ Innovative Research Project of Shandong University of Science and Technology

Directory of Open Access Journals (Sweden)

Wang Yanxia

2017-01-01

Full Text Available In order to improve the quality of undergraduate education and combine theory and practice, Shandong University of science and technology organized innovative research activities project for undergraduates. Combined with the characteristics of engineering mechanics course, teachers of engineering mechanics teaching and research section guided students to take an active part in scientific research and innovation practice teaching, which has obtained a good teaching effect. This paper introduces the concrete implement process of the college students’ innovative scientific research project “Experiment Study on Elastic Indicator of Thermal Shock Ceramic Materials”, which measures elastic indicator of ceramics using the ultrasonic method. This paper studies elastic indicator change rule of the mullite ceramic samples under different factors such as temperature difference, thermal shock times and so on. Studies have shown that in the condition of air-cooling, with the increase of thermal shock temperature difference and thermal shock times, the elastic modulus value, shear modulus and Poisson’s ratio are in a falling trend. The project implementation have proved that implement undergraduate innovation research projects could effectively arouse students’ learning enthusiasm, cultivate students’ scientific research innovation and analytical abilities to solve practical scientific research problems.

X-ray diffraction measurements in KCl shocked along [100

International Nuclear Information System (INIS)

D'Almeida, T.; Gupta, Y.M.

2000-01-01

Real time x-ray diffraction measurements were used to examine the polymorphic phase transformation in KCl shocked along the [100] direction. Shock wave continuum data, obtained previously by Hayes, were used to design the experiments and to predict diffraction from KCl shocked to different peak stresses. Here, we present the results obtained below the transition stress: between 1.4 and 2 GPa. Diffraction data obtained were quantitatively related to macroscopic compression. Interplanar spacing measurements revealed isotropic compression of the unit cell in contrast to previously reported results. Above the transition stress, descriptions of the atomic arrangement with respect to shock propagation (not available in the literature) are required for setting up the detection system. Hence, continuum results in combination with various crystallographic considerations were utilized to obtain data above the transition stress

Microjetting from a grooved Al surface under supported and unsupported shocks

Science.gov (United States)

Shao, Jian-Li; Wang, Pei; He, An-Min

2014-08-01

Using molecular dynamics methods, we simulate and compare the microjetting from a grooved Al surface induced by supported and unsupported shocks at different breakout pressures. Via the analysis on the microjetting morphologies and mass distributions, we find that the threshold of shock breakout pressure for the microjetting formation is almost same, but the variation of microjet mass with shock pressure shows a great difference for the two loading patterns. Under supported shock loading, the microjet mass keeps a continuous increase with increasing shock pressure, and release melting can enhance it markedly. By contrast, the microjet mass under unsupported shocks is smaller and seems no remarkable increase with shock pressure in our simulations (at extremely short pulses), implying the shock decaying can weaken the microjetting. Of course, a large area of fragments near the surface may form in this case. The microjet source distributions corresponding to supported and unsupported shocks are presented. It is found that the former becomes apparently broader than the latter with increasing shock pressure. Besides, the microjet tip velocity under supported shocks may appear a reduction because of the material strength effect below release melting. While under unsupported shocks, all the microjets in solid and melted states will experience the reduction of tip velocity. These decrements of tip velocity can be fitted by an exponential function.

Direct measurement technique for shock wave velocity with irradiation drive

International Nuclear Information System (INIS)

Wang Feng; Peng Xiaoshi; Liu Shenye; Jiang Xiaohua; Ding Yongkun

2011-01-01

According to the ionization mechanism of transparent material under super high pressure, the direct diagnosis method of shock wave has been analyzed. With the Drude free electron model, the reflectivity difference of shock wave front under different pressures was analyzed. The blank effect in the detector was studied, which is caused by the X-ray ionization of transparent material, after analyzing the reflectivity data in space-time scale. The experiment shows that the beginning point and duration of blank effect are consistent with the start point and duration of laser pulse, respectively. And the reflectivity of shock wave front is about 35% when the shock velocity is 32 km/s. The reason and solution for blank effect was presented. The formula to calculate the shock wave velocity in transparent material was also deduced and verified. (authors)

Ablative stabilization of Rayleigh-Taylor instabilities resulting from a laser-driven radiative shock

Science.gov (United States)

Huntington, C. M.; Shimony, A.; Trantham, M.; Kuranz, C. C.; Shvarts, D.; Di Stefano, C. A.; Doss, F. W.; Drake, R. P.; Flippo, K. A.; Kalantar, D. H.; Klein, S. R.; Kline, J. L.; MacLaren, S. A.; Malamud, G.; Miles, A. R.; Prisbrey, S. T.; Raman, K. S.; Remington, B. A.; Robey, H. F.; Wan, W. C.; Park, H.-S.

2018-05-01

The Rayleigh-Taylor (RT) instability is a common occurrence in nature, notably in astrophysical systems like supernovae, where it serves to mix the dense layers of the interior of an exploding star with the low-density stellar wind surrounding it, and in inertial confinement fusion experiments, where it mixes cooler materials with the central hot spot in an imploding capsule and stifles the desired nuclear reactions. In both of these examples, the radiative flux generated by strong shocks in the system may play a role in partially stabilizing RT instabilities. Here, we present experiments performed on the National Ignition Facility, designed to isolate and study the role of radiation and heat conduction from a shock front in the stabilization of hydrodynamic instabilities. By varying the laser power delivered to a shock-tube target with an embedded, unstable interface, the radiative fluxes generated at the shock front could be controlled. We observe decreased RT growth when the shock significantly heats the medium around it, in contrast to a system where the shock did not produce significant heating. Both systems are modeled with a modified set of buoyancy-drag equations accounting for ablative stabilization, and the experimental results are consistent with ablative stabilization when the shock is radiative. This result has important implications for our understanding of astrophysical radiative shocks and supernova radiative hydrodynamics [Kuranz et al., Nature Communications 9(1), 1564 (2018)].

Directly acting spring loaded safety valves as shock reducing measure

International Nuclear Information System (INIS)

Ismaier, A.; Schluecker, E.

2010-01-01

Hydraulic shocks as induced by fast closure of armatures or by sudden pump failures are massive impacts in piping systems and require extensive measures to absorb the generated load. Basically the avoidance of water hammers are preferable but in case of emergency shutdowns unavoidable hydraulic shocks have to be reduced by appropriate measures. The authors describe experiments with spring loaded safety valves as shock reducing measures. It was shown that the vale dimensions is essential for the efficacy. A realistic modeling is possible using the one-dimensional fluid mechanics code ROLAST.

The interaction of laser driven shock waves with a spherical density perturbation

International Nuclear Information System (INIS)

Bach, D.R; Budil, K.S.; Klein, R.I.; Perry, T.S.

1999-01-01

Strong shock waves produced by illumination of a CH target by laser produced x-rays were driven through a copper sphere. The motion and deformation of the sphere were measured using radiographs generated by backlighting the sphere with a large area backlighter. The sphere became non-spherical after the passage of the shock, having a complicated down-stream structure. This was an instability-induced structure that was predicted by calculations. The experiment is a convenient laboratory model of the complicated interactions occurring in much larger systems such as in astrophysics in the interaction of shocks formed in the interstellar medium with various types of clouds. In particular, the experiment is a useful tool for checking the computational ability of the new generation ASCI computers, as it requires three-dimensional modeling. This experiment has shown that three dimensional calculations seem to be necessary to describe major features observed in the experiment. Any attempt to explain hydrodynamic behavior with similar instabilities must take into account these three dimensional effects

Intense laser driven collision-less shock and ion acceleration in magnetized plasmas

Science.gov (United States)

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.

Shock tube experiments on nitromethane and Promotion of chemical reactions by non-thermal plasma

Energy Technology Data Exchange (ETDEWEB)

Seljeskog, Morten

2002-06-01

This dissertation was undertaken to study two different subjects both related to molecular decomposition by applying a shock tube and non-thermal plasma to decompose selected hydrocarbons. The first approach to molecular decomposition concerned thermal decomposition and oxidation of highly diluted nitromethane (NM) in a shock tube. Reflected shock tube experiments on NM decomposition, using mixtures of 0.2 to 1.5 vol% NM in nitrogen or argon were performed over the temperature range 850-1550 K and pressure range 190-900 kPa, with 46 experiments diluted in nitrogen and 44 diluted in argon. By residual error analysis of the measured decomposition profiles it was found that NM decomposition (CH{sub 3}NO{sub 2} + M {yields} CH{sub 3} + NO{sub 2} + M, where M = N{sub 2} /Ar) corresponds well to a law of first order. Arrhenius expressions corresponding to NM diluted either in N{sub 2} or in Ar were found as k{sub N2} = 10{sup 17.011} * exp(- 182.6 kJ/mole / R*T) and k{sub Ar} = 10{sup 17.574}*exp(-207 kJ/mole / R*T ) , respectively. A new reaction mechanism was then proposed, based on new experimental data for NM decomposition both in Ar and N{sub 2} and on three previously developed mechanisms. The new mechanism predicts well the decomposition of NM diluted in both N{sub 2} and Ar within the pressure and temperature range covered by the experiments. In parallel to, and following the decomposition experiments, oxidative experiments on the ignition delay times of NM/O{sub 2}/Ar mixtures were investigated over high temperature and low to high pressure ranges. These experiments were carried out with eight different mixtures of gaseous NM and oxygen diluted in argon, with pressures ranging between 44.3-600 kPa, and temperatures ranging between 842-1378 K. The oxidation experiments were divided into different categories according to the type of decomposition signals achieved. For signals with and without emission, the apparent quasi

Evaluation of XHVRB for Capturing Explosive Shock Desensitization

Science.gov (United States)

Tuttle, Leah; Schmitt, Robert; Kittell, Dave; Harstad, Eric

2017-06-01

Explosive shock desensitization phenomena have been recognized for some time. It has been demonstrated that pressure-based reactive flow models do not adequately capture the basic nature of the explosive behavior. Historically, replacing the local pressure with a shock captured pressure has dramatically improved the numerical modeling approaches. Models based upon shock pressure or functions of entropy have recently been developed. A pseudo-entropy based formulation using the History Variable Reactive Burn model, as proposed by Starkenberg, was implemented into the Eulerian shock physics code CTH. Improvements in the shock capturing algorithm were made. The model is demonstrated to reproduce single shock behavior consistent with published pop plot data. It is also demonstrated to capture a desensitization effect based on available literature data, and to qualitatively capture dead zones from desensitization in 2D corner turning experiments. This models shows promise for use in modeling and simulation problems that are relevant to the desensitization phenomena. Issues are identified with the current implementation and future work is proposed for improving and expanding model capabilities. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Coping with anxiety and rebuilding identity: A psychosynthesis approach to culture shock

NARCIS (Netherlands)

Lombard, Catherine Ann

2014-01-01

As the number of international students continues to increase worldwide, their experience of culture shock has been well-researched. Missing, however, from the culture shock literature is the perspective of psychosynthesis psychology and its methodology to deal with the affective, behavioral, and

Formation and damping of a shock wave induced by laser in a metallic target

International Nuclear Information System (INIS)

Cottet, F.

1981-01-01

In the first part of this work, a numerical simulation of the formation and of the damping of the shock wave induced in a solid target by a laser impulse is developed. It allows to interpret the experimental obtained in the second part of the study. Two series of experiments have been realized. An iron target metallographic study is intended to verify if laser shocks produce effects comparable with conventional shocks, particularly a deformation by albite twinning the existence of which is related to the shock amplitude and its evolution during the propagation in the target. Macles observation become a possible mean to estimate the value of the induced pressures. Another experiment series has been realized to determine more directly the shock parameters. Piezoelectric cermets have been used to detect a shock-wave passage and to measure the time taken to go through targets of variable thickness. The numerical solution allows, afterwards, to deduce the maximum pressure of the induced shock. The most part of the tests have been done on copper targets, the behaviour of which is well known in a large pressure domain. Some tests have been realized on aluminium and iron targets [fr

Fundamental structure of steady plastic shock waves in metals

Science.gov (United States)

Molinari, A.; Ravichandran, G.

2004-02-01

materials subjected to very high strain rates from shock wave experiments is discussed.

Fundamental structure of steady plastic shock waves in metals

International Nuclear Information System (INIS)

Molinari, A.; Ravichandran, G.

2004-01-01

materials subjected to very high strain rates from shock wave experiments is discussed

MANAGEMENT OF RENEWABLE ENERGY AND REGIONAL DEVELOPMENT: EUROPEAN EXPERIENCES AND STEPS FORWARD

OpenAIRE

Andreea Ileana Zamfir

2011-01-01

The issues of the renewable energy and regional development have become major priorities for public policymakers across the globe. Therefore, this study explores some European experiences and steps forward in the field of the management of renewable energy and regional development. Firstly, an overview of renewable energy issues in European regions is revealed, and secondly, some measures and actions for managing regional development of renewable energy in Romania taking into account the fina...

Experimental and Theoretical Investigation of Shock-Induced Reactions in Energetic Materials

Energy Technology Data Exchange (ETDEWEB)

Kay, Jeffrey J. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Park, Samuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kohl, Ian Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knepper, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Farrow, Darcie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tappan, Alexander S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

In this work, shock-induced reactions in high explosives and their chemical mechanisms were investigated using state-of-the-art experimental and theoretical techniques. Experimentally, ultrafast shock interrogation (USI, an ultrafast interferometry technique) and ultrafast absorption spectroscopy were used to interrogate shock compression and initiation of reaction on the picosecond timescale. The experiments yielded important new data that appear to indicate reaction of high explosives on the timescale of tens of picoseconds in response to shock compression, potentially setting new upper limits on the timescale of reaction. Theoretically, chemical mechanisms of shock-induced reactions were investigated using density functional theory. The calculations generated important insights regarding the ability of several hypothesized mechanisms to account for shock-induced reactions in explosive materials. The results of this work constitute significant advances in our understanding of the fundamental chemical reaction mechanisms that control explosive sensitivity and initiation of detonation.

Microsoft® Office Visio® 2007 Step by Step

CERN Document Server

Lemke, Judy

2009-01-01

Experience learning made easy-and quickly teach yourself how to create professional-looking business and technical diagrams with Visio 2007. With Step By Step, you set the pace-building and practicing the skills you need, just when you need them! Build organization charts, floor plans, and other diagramsAdd color, text, and other effectsConnect shapes and create effective flowchartsVisualize and analyze data with new PivotDiagramsInsert and modify diagrams in other Microsoft Office documentsCreate your own shapes and templates and build custom diagrams Your all-in-one learning experience in

Report of 22nd International Symposium on Shock Waves; Dai 22 kai kokusai shogekiha symposium shusseki hokoku

Energy Technology Data Exchange (ETDEWEB)

Takayama, K. [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science

1999-11-05

Outlined herein are the topics at the 22nd. International Symposium on Shock Waves, held in July 1999 in London. Prof. Takayama of Tohoku University gave an invited lecture on application of shock waves to medical area, stressing significance of shock waves on a human body. A total of 81 papers were presented from Japan. Number of Japanese papers and number of Japanese attendees both accounted for approximately 25%. The themes of these papers are centered by behavior of shock waves (e.g., propagation, reflection, and diffraction), extreme supersonic flows, interference between shock wave and boundary layer, aerodynamics (e.g., interference between vortex and shock wave), numerical simulation of shock wave phenomena, development of a new shock wave tube and measurement method, researches on elementary steps in chemical reactions, shock wave phenomena in condensed media and multi-phase media, shock wave noise produced while a high-speed train is running in a tunnel, and application of shock waves to industrial and medical areas. Japan contributes much to the application to medical area, and a method dispensing with injection is reported. Japan's aerospace-related researches include interference between shock wave and boundary layer, in which the real gas effect is taken into consideration, designs for protection from heat during the re-entry into the atmosphere, and construction of the world largest free-piston type wind tunnel. (NEDO)

Measurements of ion velocity separation and ionization in multi-species plasma shocks

Science.gov (United States)

Rinderknecht, Hans G.; Park, H.-S.; Ross, J. S.; Amendt, P. A.; Wilks, S. C.; Katz, J.; Hoffman, N. M.; Kagan, G.; Vold, E. L.; Keenan, B. D.; Simakov, A. N.; Chacón, L.

2018-05-01

The ion velocity structure of a strong collisional shock front in a plasma with multiple ion species is directly probed in laser-driven shock-tube experiments. Thomson scattering of a 263.25 nm probe beam is used to diagnose ion composition, temperature, and flow velocity in strong shocks ( M ˜6 ) propagating through low-density ( ρ˜0.1 mg/cc) plasmas composed of mixtures of hydrogen (98%) and neon (2%). Within the preheat region of the shock front, two velocity populations of ions are observed, a characteristic feature of strong plasma shocks. The ionization state of the Ne is observed to change within the shock front, demonstrating an ionization-timescale effect on the shock front structure. The forward-streaming proton feature is shown to be unexpectedly cool compared to predictions from ion Fokker-Planck simulations; the neon ionization gradient is evaluated as a possible cause.

Nonlinear Weibel Instability and Turbulence in Strong Collisionless Shocks

International Nuclear Information System (INIS)

Medvedev, Mikhail M.

2008-01-01

This research project was devoted to studies of collisionless shocks, their properties, microphysics and plasma physics of underlying phenomena, such as Weibel instability and generation of small-scale fields at shocks, particle acceleration and transport in the generated random fields, radiation mechanisms from these fields in application to astrophysical phenomena and laboratory experiments (e.g., laser-plasma and beam-plasma interactions, the fast ignition and inertial confinement, etc.). Thus, this study is highly relevant to astrophysical sciences, the inertial confinement program and, in particular, the Fast Ignition concept, etc. It makes valuable contributions to the shock physics, nonlinear plasma theory, as well as to the basic plasma science, in general

Shock parameter calculations at weak interplanetary shock waves

Directory of Open Access Journals (Sweden)

J. M. Gloag

2005-02-01

Full Text Available A large set of interplanetary shock waves observed using the Ulysses spacecraft is analysed in order to determine their local parameters. For the first time a detailed analysis is extended to the thermodynamic properties of a large number of events. The intention is to relate the shock parameters to the requirements set by MHD shock theory. A uniform approach is adopted in the selection of up and downstream regions for this analysis and applied to all the shock waves. Initially, the general case of a 3 component adiabatic plasma is considered. However, the calculation of magnetosonic and Alfvénic Mach numbers and the ratio of downstream to upstream entropy produce some unexpected results. In some cases there is no clear increase in entropy across the shock and also the magnetosonic Mach number can be less than 1. It is found that a more discerning use of data along with an empirical value for the polytropic index can raise the distribution of downstream to upstream entropy ratios to a more acceptable level. However, it is also realised that many of these shocks are at the very weakest end of the spectrum and associated phenomena may also contribute to the explanation of these results.

Use of Z pinch radiation sources for high pressure shock wave studies

International Nuclear Information System (INIS)

Asay, J.R.; Konrad, C.H.; Hall, C.A.; Trott, W.M.; Chandler, G.A.; Holland, K.G.; Fleming, K.J.; Trucano, T.G.

1998-01-01

Recent developments in pulsed power technology demonstrate use of intense radiation sources (Z pinches) for driving planar shock waves in samples with spatial dimensions larger than possible with other radiation sources. Initial indications are that the use of Z pinch sources can be used to produce planar shock waves in samples with diameters of a few millimeters and thicknesses approaching one half millimeter. These dimensions allow increased accuracy of both shock velocity and particle velocity measurements. The Z pinch radiation source uses imploding metal plasma induced by self-magnetic fields applied to wire arrays to produce high temperature x-ray environments in vacuum hohlraum enclosures. Previous experiments have demonstrated that planar shock waves can be produced with this approach. A photograph of a wire array located inside the vacuum hohlraum is shown here. Typically, a few hundred individual wires are used to produce the Z pinch source. For the shock wave experiments being designed, arrays of 120 to 240 tungsten wires with a diameter of 40 mm and with individual diameters of about 10 microm are used. Preliminary experiments have been performed on the Z pulsed radiation source to demonstrate the ability to obtain VISAR measurements in the Z accelerator environment. Analysis of these results indicate that another effect, not initially anticipated, is an apparent change in refractive index that occurs in the various optical components used in the system. This effect results in an apparent shift in the frequency of reflected laser light, and causes an error in the measured particle velocity. Experiments are in progress to understand and minimize this effect

Shock fabrics in fine-grained micrometeorites

Science.gov (United States)

Suttle, M. D.; Genge, M. J.; Russell, S. S.

2017-10-01

The orientations of dehydration cracks and fracture networks in fine-grained, unmelted micrometeorites were analyzed using rose diagrams and entropy calculations. As cracks exploit pre-existing anisotropies, analysis of their orientation provides a mechanism with which to study the subtle petrofabrics preserved within fine-grained and amorphous materials. Both uniaxial and biaxial fabrics are discovered, often with a relatively wide spread in orientations (40°-60°). Brittle deformation cataclasis and rotated olivine grains are reported from a single micrometeorite. This paper provides the first evidence for impact-induced shock deformation in fine-grained micrometeorites. The presence of pervasive, low-grade shock features in CM chondrites and CM-like dust, anomalously low-density measurements for C-type asteroids, and impact experiments which suggest CM chondrites are highly prone to disruption all imply that CM parent bodies are unlikely to have remained intact and instead exist as a collection of loosely aggregated rubble-pile asteroids, composed of primitive shocked clasts.

Interplanetary fast shock diagnosis with the radio receiver on Ulysses

Science.gov (United States)

Hoang, S.; Pantellini, F.; Harvey, C. C.; Lacombe, C.; Mangeney, A.; Meuer-Vernet, N.; Perche, C.; Steinberg, J.-L.; Lengyel-Frey, D.; Macdowall, R. J.

1992-01-01

The radio receiver on Ulysses records the quasi-thermal noise which allows a determination of the density and temperature of the cold (core) electrons of the solar wind. Seven interplanetary fast forward or reverse shocks are identified from the density and temperature profiles, together with the magnetic field profile from the Magnetometer experiment. Upstream of the three strongest shocks, bursts of nonthermal waves are observed at the electron plasma frequency f(peu). The more perpendicular the shock, the longer the time interval during which these upstream bursts are observed. For one of the strongest shocks we also observe two kinds of upstream electromagnetic radiation: radiation at 2 f(peu), and radiation at the downstream electron plasma frequency, which propagates into the less dense upstream regions.

Formation of large-amplitude dust ion-acoustic shocks in dusty plasmas

International Nuclear Information System (INIS)

Eliasson, B.; Shukla, P.K.

2005-01-01

Theoretical and numerical studies of self-steepening and shock formation of large-amplitude dust ion-acoustic waves in dusty plasmas are presented. A comparison is made between the nondispersive two fluid model, which predicts the formation of large-amplitude compressive and rarefactive dust ion-acoustic shocks, Vlasov simulations, and recent laboratory experiments

High-energy air shock study in steel and grout pipes

International Nuclear Information System (INIS)

Glenn, H.D.; Kratz, H.R.; Keough, D.D.; Duganne, D.A.; Ruffner, D.J.; Swift, R.P.; Baum, D.

1979-01-01

Voitenko compressors are used to generate 43 mm/μs air shocks in both a steel and a grout outlet pipe containing ambient atmospheric air. Fiber-optic ports provide diaphragm burst times, time-of-arrival (TOA) data, and velocities for the shock front along the 20-mm-ID exit pipes. Pressure profiles are obtained at higher enthalpy shock propagation than ever before and at many locations along the exit pipes. Numerous other electronic sensors and postshot observations are described, as well as experimental results. The primary objectives of the experiments are as follows: (1) provide a data base for normalization/improvement of existing finite-difference codes that describe high-energy air shocks and gas propagation; (2) obtain quantitative results on the relative attenuation effects of two very different wall materials for high-energy air shocks and gas flows. The extensive experimental results satisfy both objectives

Ultrafast dynamic ellipsometry and spectroscopy of laser shocked materials

Energy Technology Data Exchange (ETDEWEB)

Mcgrane, Shawn David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bolme, Cindy B [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Whitley, Von H [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Moore, David S [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2010-01-01

Shock waves create extreme states of matter with very high pressures, temperatures, and volumetric compressions, at an exceedingly rapid rate of change. We review how to use a beamsplitter and a note card to turn a typical chirp pulse amplified femtosecond laser system into an ultrafast shock dynamics machine. Open scientific questions that can be addressed with such an apparatus are described. We report on the development of several single shot time resolved diagnostics needed to answer these questions. These single shot diagnostics are expected to be broadly applicable to other types of laser ablation experiments. Experimental results measured from shocked material dynamics of several systems are detailed. Finally, we report on progress towards using transient absorption as a measure of electronic excitation and coherent Raman as a picosecond probe of temperature in shock compressed condensed matter.

Scaling Laws for Unstable Interfaces Driven by Strong Shocks in Cylindrical Geometry

International Nuclear Information System (INIS)

Zhang, Q.; Graham, M.J.; Graham, M.J.

1997-01-01

The Richtmyer-Meshkov (RM) instability is an interfacial interface between two fluids of different densities driven by shock waves and plays an important role in the studies of inertial confinement fusion and of supernovas. So far, most of the studies are for RM unstable interfaces driven by weak or intermediate shocks in planar geometry. For experiments conducted at the Nova laser, the unstable material interface is accelerated by very strong shocks. In this Letter, we present scaling laws for the RM unstable interface driven by strong imploding and exploding shocks. copyright 1997 The American Physical Society

Shock Mechanism Analysis and Simulation of High-Power Hydraulic Shock Wave Simulator

Directory of Open Access Journals (Sweden)

Xiaoqiu Xu

2017-01-01

Full Text Available The simulation of regular shock wave (e.g., half-sine can be achieved by the traditional rubber shock simulator, but the practical high-power shock wave characterized by steep prepeak and gentle postpeak is hard to be realized by the same. To tackle this disadvantage, a novel high-power hydraulic shock wave simulator based on the live firing muzzle shock principle was proposed in the current work. The influence of the typical shock characteristic parameters on the shock force wave was investigated via both theoretical deduction and software simulation. According to the obtained data compared with the results, in fact, it can be concluded that the developed hydraulic shock wave simulator can be applied to simulate the real condition of the shocking system. Further, the similarity evaluation of shock wave simulation was achieved based on the curvature distance, and the results stated that the simulation method was reasonable and the structural optimization based on software simulation is also beneficial to the increase of efficiency. Finally, the combination of theoretical analysis and simulation for the development of artillery recoil tester is a comprehensive approach in the design and structure optimization of the recoil system.

Iteratively improving Hi-C experiments one step at a time.

Science.gov (United States)

Golloshi, Rosela; Sanders, Jacob T; McCord, Rachel Patton

2018-04-30

The 3D organization of eukaryotic chromosomes affects key processes such as gene expression, DNA replication, cell division, and response to DNA damage. The genome-wide chromosome conformation capture (Hi-C) approach can characterize the landscape of 3D genome organization by measuring interaction frequencies between all genomic regions. Hi-C protocol improvements and rapid advances in DNA sequencing power have made Hi-C useful to study diverse biological systems, not only to elucidate the role of 3D genome structure in proper cellular function, but also to characterize genomic rearrangements, assemble new genomes, and consider chromatin interactions as potential biomarkers for diseases. Yet, the Hi-C protocol is still complex and subject to variations at numerous steps that can affect the resulting data. Thus, there is still a need for better understanding and control of factors that contribute to Hi-C experiment success and data quality. Here, we evaluate recently proposed Hi-C protocol modifications as well as often overlooked variables in sample preparation and examine their effects on Hi-C data quality. We examine artifacts that can occur during Hi-C library preparation, including microhomology-based artificial template copying and chimera formation that can add noise to the downstream data. Exploring the mechanisms underlying Hi-C artifacts pinpoints steps that should be further optimized in the future. To improve the utility of Hi-C in characterizing the 3D genome of specialized populations of cells or small samples of primary tissue, we identify steps prone to DNA loss which should be considered to adapt Hi-C to lower cell numbers. Copyright © 2018 Elsevier Inc. All rights reserved.

Alfven shock trains

International Nuclear Information System (INIS)

Malkov, M.A.; Kennel, C.F.; Wu, C.C.; Pellat, R.; Shapiro, V.D.

1991-01-01

The Cohen--Kulsrud--Burgers equation (CKB) is used to consider the nonlinear evolution of resistive, quasiparallel Alfven waves subject to a long-wavelength, plane-polarized, monochromatic instability. The instability saturates by nonlinear steepening, which proceeds until the periodic waveform develops an interior scale length comparable to the dissipation length; a fast or an intermediate shock then forms. The result is a periodic train of Alfven shocks of one or the other type. For propagation strictly parallel to the magnetic field, there will be two shocks per instability wavelength. Numerical integration of the time-dependent CKB equation shows that an initial, small-amplitude growing wave asymptotes to a stable, periodic stationary wave whose analytic solution specifies how the type of shock embedded in the shock train, and the amplitude and speed of the shock train, depend on the strength and phase of the instability. Waveforms observed upstream of the Earth's bowshock and cometary shocks resemble those calculated here

Optical Spectroscopy Measurements of Shock Waves Driven by Intense Z-Pinch Radiation

International Nuclear Information System (INIS)

Asay, J.; Bernard, M.; Bailey, J.E.; Carlson, A.L.; Chandler, G.A.; Hall, C.A.; Hanson, D.; Johnston, R.; Lake, P.; Lawrence, J.

1999-01-01

Z-pinches created using the Z accelerator generate approximately220 TW, 1.7 MJ radiation pulses that heat large (approximately10 cm 3 ) hohlraums to 100-150 eV temperatures for times of order 10 nsec. We are performing experiments exploiting this intense radiation to drive shock waves for equation of state studies. The shock pressures are typically 1-10 Mbar with 10 nsec duration in 6-mm-diameter samples. In this paper we demonstrate the ability to perform optical spectroscopy measurements on shocked samples located in close proximity to the z-pinch. These experiments are particularly well suited to optical spectroscopy measurements because of the relatively large sample size and long duration. The optical emission is collected using fiber optics and recorded with a streaked spectrograph. Other diagnostics include VISAR and active shock breakout measurements of the shocked sample and a suite of diagnostics that characterize the radiation drive. Our near term goal is to use the spectral emission to obtain the temperature of the shocked material. Longer term objectives include the examination of deviations of the spectrum from blackbody, line emission from lower density regions, determination of kinetic processes in molecular systems, evaluation of phase transitions such as the onset of metalization in transparent materials, and characterization of the plasma formed when the shock exits the rear surface. An initial set of data illustrating both the potential and the challenge of these measurements is described

Nonequilibrium radiation behind a strong shock wave in CO 2-N 2

Science.gov (United States)

Rond, C.; Boubert, P.; Félio, J.-M.; Chikhaoui, A.

2007-11-01

This work presents experiments reproducing plasma re-entry for one trajectory point of a Martian mission. The typical facility to investigate such hypersonic flow is shock tube; here we used the free-piston shock tube TCM2. Measurements of radiative flux behind the shock wave are realized thanks to time-resolved emission spectroscopy which is calibrated in intensity. As CN violet system is the main radiator in near UV-visible range, we have focused our study on its spectrum. Moreover a physical model, based on a multi-temperature kinetic code and a radiative code, for calculation of non equilibrium radiation behind a shock wave is developed for CO 2-N 2-Ar mixtures. Comparisons between experiments and calculations show that standard kinetic models (Park, McKenzie) are inefficient to reproduce our experimental results. Therefore we propose new rate coefficients in particular for the dissociation of CO 2, showing the way towards a better description of the chemistry of the mixture.

Is shock index associated with outcome in children with sepsis/septic shock?*.

Science.gov (United States)

Yasaka, Yuki; Khemani, Robinder G; Markovitz, Barry P

2013-10-01

To investigate the association between PICU shock index (the ratio of heart rate to systolic blood pressure) and PICU mortality in children with sepsis/septic shock. To explore cutoff values for shock index for ICU mortality, how change in shock index over the first 6 hours of ICU admission is associated with outcome, and how the use of vasoactive therapy may affect shock index and its association with outcome. Retrospective cohort. Single-center tertiary PICU. Five hundred forty-four children with the diagnosis of sepsis/septic shock. None. From January 2003 to December 2009, 544 children met International Pediatric Sepsis Consensus Conference of 2005 criteria for sepsis/septic shock. Overall mortality was 23.7%. Among all patients, hourly shock index was associated with mortality: odds ratio of ICU mortality at 0 hour, 1.08, 95% CI (1.04-1.12); odds ratio at 1 hour, 1.09 (1.04-1.13); odds ratio at 2 hours, 1.09 (1.05-1.13); and odds ratio at 6 hours, 1.11 (1.06-1.15). When stratified by age, early shock index was associated with mortality only in children 1-3 and more than or equal to 12 years old. Area under the receiver operating characteristic curve in age 1-3 and more than or equal to 12 years old for shock index at admission was 0.69 (95% CI, 0.58-0.80) and 0.62 (95% CI, 0.52-0.72) respectively, indicating a fair predictive marker. Although higher shock index was associated with increased risk of mortality, there was no particular cutoff value with adequate positive or negative likelihood ratios to identify mortality in any age group of children. The improvement of shock index in the first 6 hours of ICU admission was not associated with outcome when analyzed in all patients. However, among patients whose shock index were above the 50th percentile at ICU admission for each age group, improvement of shock index was associated with lower ICU mortality in children between 1-3 and more than or equal to 12 years old (p = 0.02 and p = 0.03, respectively). When

Laser-excited optical emission response of CdTe quantum dot/polymer nanocomposite under shock compression

Energy Technology Data Exchange (ETDEWEB)

Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Kang, Zhitao; Summers, Christopher J. [Phosphor Technology Center of Excellence, Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); Bansihev, Alexandr A.; Christensen, James M.; Dlott, Dana D. [School of Chemical Sciences and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Breidenich, Jennifer; Scripka, David A.; Thadhani, Naresh N. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Zhou, Min, E-mail: min.zhou@gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States)

2016-01-04

Laser-driven shock compression experiments and corresponding finite element method simulations are carried out to investigate the blueshift in the optical emission spectra under continuous laser excitation of a dilute composite consisting of 0.15% CdTe quantum dots by weight embedded in polyvinyl alcohol polymer. This material is a potential candidate for use as internal stress sensors. The analyses focus on the time histories of the wavelength blue-shift for shock loading with pressures up to 7.3 GPa. The combined measurements and calculations allow a relation between the wavelength blueshift and pressure for the loading conditions to be extracted. It is found that the blueshift first increases with pressure to a maximum and subsequently decreases with pressure. This trend is different from the monotonic increase of blueshift with pressure observed under conditions of quasistatic hydrostatic compression. Additionally, the blueshift in the shock experiments is much smaller than that in hydrostatic experiments at the same pressure levels. The differences in responses are attributed to the different stress states achieved in the shock and hydrostatic experiments and the time dependence of the mechanical response of the polymer in the composite. The findings offer a potential guide for the design and development of materials for internal stress sensors for shock conditions.

A composite model for a class of electric-discharge shock tubes

Science.gov (United States)

Elkins, R. T.; Baganoff, D.

1973-01-01

A gasdynamic model is presented and analyzed for a class of shock tubes that utilize both Joule heating and electromagnetic forces to produce high-speed shock waves. The model consists of several stages of acceleration in which acceleration to sonic conditions is achieved principally through heating, and further acceleration of the supersonic flow is obtained principally through use of electromagnetic forces. The utility of the model results from the fact that it predicts a quasi-steady flow process, mathematical analysis is straightforward, and it is even possible to remove one or more component stages and still have the model related to a possible shock-tube flow. Initial experiments have been performed where the electrical discharge configuration and current level were such that Joule heating was the dominant form of energy addition present. These experiments indicate that the predictions of the model dealing with heat addition correspond quite closely to reality. The experimental data together with the theory show that heat addition to the flowing driver gas after diaphragm rupture (approach used in the model) is much more effective in producing high-speed shock waves than heating the gas in the driver before diaphragm rupture, as in the case of the arc-driven shock tube.

Experimental and numerical investigations of shock wave propagation through a bifurcation

Science.gov (United States)

Marty, A.; Daniel, E.; Massoni, J.; Biamino, L.; Houas, L.; Leriche, D.; Jourdan, G.

2018-02-01

The propagation of a planar shock wave through a split channel is both experimentally and numerically studied. Experiments were conducted in a square cross-sectional shock tube having a main channel which splits into two symmetric secondary channels, for three different shock wave Mach numbers ranging from about 1.1 to 1.7. High-speed schlieren visualizations were used along with pressure measurements to analyze the main physical mechanisms that govern shock wave diffraction. It is shown that the flow behind the transmitted shock wave through the bifurcation resulted in a highly two-dimensional unsteady and non-uniform flow accompanied with significant pressure loss. In parallel, numerical simulations based on the solution of the Euler equations with a second-order Godunov scheme confirmed the experimental results with good agreement. Finally, a parametric study was carried out using numerical analysis where the angular displacement of the two channels that define the bifurcation was changed from 90° , 45° , 20° , and 0° . We found that the angular displacement does not significantly affect the overpressure experience in either of the two channels and that the area of the expansion region is the important variable affecting overpressure, the effect being, in the present case, a decrease of almost one half.

Extended Lagrangian Born-Oppenheimer molecular dynamics simulations of the shock-induced chemistry of phenylacetylene

Energy Technology Data Exchange (ETDEWEB)

Cawkwell, M. J., E-mail: cawkwell@lanl.gov; Niklasson, Anders M. N. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Dattelbaum, Dana M. [Weapons Experiments Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2015-02-14

The initial chemical events that occur during the shock compression of liquid phenylacetylene have been investigated using self-consistent tight binding molecular dynamics simulations. The extended Lagrangian Born-Oppenheimer molecular dynamics formalism enabled us to compute microcanonical trajectories with precise conservation of the total energy. Our simulations revealed that the first density-increasing step under shock compression arises from the polymerization of phenylacetylene molecules at the acetylene moiety. The application of electronic structure-based molecular dynamics with long-term conservation of the total energy enabled us to identify electronic signatures of reactivity via monitoring changes in the HOMO-LUMO gap, and to capture directly adiabatic shock heating, transient non-equilibrium states, and changes in temperature arising from exothermic chemistry in classical molecular dynamics trajectories.

Extended Lagrangian Born-Oppenheimer molecular dynamics simulations of the shock-induced chemistry of phenylacetylene.

Science.gov (United States)

Cawkwell, M J; Niklasson, Anders M N; Dattelbaum, Dana M

2015-02-14

The initial chemical events that occur during the shock compression of liquid phenylacetylene have been investigated using self-consistent tight binding molecular dynamics simulations. The extended Lagrangian Born-Oppenheimer molecular dynamics formalism enabled us to compute microcanonical trajectories with precise conservation of the total energy. Our simulations revealed that the first density-increasing step under shock compression arises from the polymerization of phenylacetylene molecules at the acetylene moiety. The application of electronic structure-based molecular dynamics with long-term conservation of the total energy enabled us to identify electronic signatures of reactivity via monitoring changes in the HOMO-LUMO gap, and to capture directly adiabatic shock heating, transient non-equilibrium states, and changes in temperature arising from exothermic chemistry in classical molecular dynamics trajectories.

Biomass shock pretreatment

Science.gov (United States)

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

2014-07-01

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

Shock physics with the nova laser for ICF applications. Revision 1

International Nuclear Information System (INIS)

Hammel, B.A.; Cauble, R.; Celliers, P.

1995-01-01

The physics of high pressure shocks plays a central role in Inertial Confinement Fusion (ICF). In indirect drive ICF, x-rays from a gold cavity (hohlraum) are used to ablatively drive a series of high pressure shocks into a spherical target (capsule). These shocks converge at the center, compressing the fuel and forming a hot dense core. The target performance, such as peak fuel density and temperature and neutron yield, depends critically on hock timing, and material compressibility. Accurate predictions of NIF target performance depends critically on shock timing and material compressibility. Current measurement techniques enable us to accurately determine shock timing in planar samples of abator material as a function of laser drive. Although this technique does not separately address uncertainties in material EOS and opacity, it does allow us to tune the laser drive until the desired shock timing is achieved. Experiments to directly address the EOS of D 2 ice are planned to further increase the margin for ignition in current target designs

Radial shock wave treatment alone is less efficient than radial shock wave treatment combined with tissue-specific plantar fascia-stretching in patients with chronic plantar heel pain.

Science.gov (United States)

Rompe, Jan D; Furia, John; Cacchio, Angelo; Schmitz, Christoph; Maffulli, Nicola

2015-12-01

Whether shock wave therapy or shock wave therapy combined with plantar fascia-specific stretching is more efficient in treating chronic plantar heel pain remains unclear. The aim of the study was to test the null hypothesis of no difference of these two forms of management for patients who had unilateral plantar fasciopathy for a minimum duration of twelve months and which had failed at least three other forms of treatment. One hundred and fifty-two patients with chronic plantar fasciopathy were assigned to receive repetitive low-energy radial shock-wave therapy without local anesthesia, administered weekly for three weeks (Group 1, n = 73) or to receive the identical shock wave treatment and to perform an eight-week plantar fascia-specific stretching program (Group 2, n = 79). All patients completed the nine-item pain subscale of the validated Foot Function Index and a subject-relevant outcome questionnaire. Patients were evaluated at baseline, and at two, four, and twenty-four months after baseline. The primary outcome measures were a mean change in the Foot Function Index sum score at two months after baseline, a mean change in item 2 (pain during the first steps of walking in the morning) on this Index, and satisfaction with treatment. No difference in mean age, sex, weight or duration of symptoms was found between the groups at baseline. At two months after baseline, the Foot Function Index sum score showed significantly greater changes for the patients managed with shock-wave therapy plus plantar fascia-specific stretching than those managed with shock-wave therapy alone (p plantar fascia in combination with repetitive low-energy radial shock-wave therapy is more efficient than repetitive low-energy radial shock-wave therapy alone for the treatment of chronic symptoms of proximal plantar fasciopathy. Copyright © 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

Decay of a laser generated shock wave in an aluminium target

International Nuclear Information System (INIS)

Werdiger, M.

1993-09-01

When a shock wave arrives at the near surface of a solid material, a radical and fast change occurs in the reflection properties of the material. The phenomenon is used in the present work in order to develop a new way to measure the transit time of a shock wave in a target. A 10 milliwatt He:Ne laser is directed toward the rear surface of the target. The reflected beam arrives at a photo-diode with a fast rise time of 150 psec which detects the instant of the change in the reflection. This technique, called 'continuous back lightning', is used in experiments with aluminium foil thickness in the range of 40μm ≤x≥ 1000μm. The shock wave is induced by a laser pulse of an intensity of 3*10 13 W/cm 2 . The results show two main physical regimes: in the first one 40μ ≤x≥ 210μm, there is a constant shock wave velocity which in our experiments was measured to be (12.81±0.67)km/s. In the second range of the thickness where 300μm there is a decay of the shock velocity. For x ≥ 210μm the geometry is one dimensional for our experimental conditions, while for x ≥ 300μm the 1-D geometry changes to 2 dimensional (2-D) geometry. The 2-D shock wave decay asymptotically (x→∞ to an acoustic wave. shock wave is described by a pressure scaling as x -n (n is a positive constant). The phenomenological equation of the state is taken to be P=A**u s + B*u s 2 +Bu s , where P is the pressure, u s - the shock velocity, A and B are constants. Applying our experimental results to the solution of the differential equation in this model A*x 2 ± B*x=C*x -n yields a value of n in the range 3.16 ≤n≥ 3.51. This pressure scaling law agrees with the self-similar solution of a concentrated impact on a surface between two media. This situation is well simulated by the laser deposition energy on a metal surface. In the experiment a 5% accuracy is achieved. Such a good accuracy has not been achieved so far in a laser induced shock-wave measurements in solids. (author). 52 refs

Shock loading and reactive flow modeling studies of void induced AP/AL/HTPB propellant

Science.gov (United States)

Miller, P. J.; Lindfors, A. J.

1998-07-01

The unreactive Hugoniot of a class 1.3 propellant has been investigated by shock compression experiments. The results are analyzed in terms of an ignition and growth reactive flow model using the DYNA2D hydrocode. The calculated shock ignition parameters of the model show a linear dependence on measured void volume which appears to reproduce the observed gauge records well. Shock waves were generated by impact in a 75 mm single stage powder gun. Manganin and PVDF pressure gauges provided pressure-time histories to 140 kbar. The propellants were of similar formulation differing only in AP particle size and the addition of a burn rate modifer (Fe2O3) from that of previous investigations. Results show neglible effect of AP particle size on shock response in contrast to the addition of Fe2O3 which appears to `stiffen' the unreactive Hugoniot and enhances significantly the reactive rates under shock. The unreactive Hugoniot, within experimental error, compares favorably to the solid AP Hugoniot. Shock experiments were performed on propellant samples strained to induce insitu voids. The material state was quantified by uniaxial tension dialatometry. The experimental records show a direct correlation between void volume (0 to 1.7%) and chemical reactivity behind the shock front. These results are discussed in terms of `hot spot' ignition resulting from the shock collapse of the voids.

Numerical Study of Richtmyer-Meshkov Instability with Re-Shock

Science.gov (United States)

Wong, Man Long; Livescu, Daniel; Lele, Sanjiva

2017-11-01

The interaction of a Mach 1.45 shock wave with a perturbed planar interface between two gases with an Atwood number 0.68 is studied through 2D and 3D shock-capturing adaptive mesh refinement (AMR) simulations with physical diffusive and viscous terms. The simulations have initial conditions similar to those in the actual experiment conducted by Poggi et al. [1998]. The development of the flow and evolution of mixing due to the interactions with the first shock and the re-shock are studied together with the sensitivity of various global parameters to the properties of the initial perturbation. Grid resolutions needed for fully resolved and 2D and 3D simulations are also evaluated. Simulations are conducted with an in-house AMR solver HAMeRS built on the SAMRAI library. The code utilizes the high-order localized dissipation weighted compact nonlinear scheme [Wong and Lele, 2017] for shock-capturing and different sensors including the wavelet sensor [Wong and Lele, 2016] to identify regions for grid refinement. First and third authors acknowledge the project sponsor LANL.

Simulation Study of Shock Reaction on Porous Material

International Nuclear Information System (INIS)

Xu Aiguo; Zhang Guangcai; Pan Xiaofei; Zhu Jianshi

2009-01-01

Direct modeling of porous materials under shock is a complex issue. We investigate such a system via the newly developed material-point method. The effects of shock strength and porosity size are the main concerns. For the same porosity, the effects of mean-void-size are checked. It is found that local turbulence mixing and volume dissipation are two important mechanisms for transformation of kinetic energy to heat. When the porosity is very small, the shocked portion may arrive at a dynamical steady state; the voids in the downstream portion reflect back rarefactive waves and result in slight oscillations of mean density and pressure; for the same value of porosity, a larger mean-void-size makes a higher mean temperature. When the porosity becomes large, hydrodynamic quantities vary with time during the whole shock-loading procedure: after the initial stage, the mean density and pressure decrease, but the temperature increases with a higher rate. The distributions of local density, pressure, temperature and particle-velocity are generally non-Gaussian and vary with time. The changing rates depend on the porosity value, mean-void-size and shock strength. The stronger the loaded shock, the stronger the porosity effects. This work provides a supplement to experiments for the very quick procedures and reveals more fundamental mechanisms in energy and momentum transportation. (general)

Oil shock transmission to stock market returns: Wavelet-multivariate Markov switching GARCH approach

International Nuclear Information System (INIS)

Jammazi, Rania

2012-01-01

Since oil prices are typically governed by nonlinear and chaotic behavior, it’s become rather difficult to capture the dominant properties of their fluctuations. In recent years, unprecedented interest emerged on the decomposition methods in order to capture drifts or spikes relatively to this data. Together, our understanding of the nature of crude oil price shocks and their effects on the stock market returns has evolved noticeably. We accommodate these findings to investigate two issues that have been at the center of recent debates on the effect of crude oil shocks on the stock market returns of five developed countries (USA, UK, Japan, Germany and Canada). First, we analyze whether shocks and or volatility emanating from two major crude oil markets are transmitted to the equity markets. We do this by applying, the Haar A Trous Wavelet decomposition to monthly real crude oil series in a first step, and the trivariate BEKK Markov Switching GARCH model to analyze the effect of the smooth part on the degree of the stock market instability in a second step. The motivation behind the use of the former method is that noises and erratic behavior often appeared at the edge of the signal, can affect the quality of the shock and thus increase erroneous results of the shock transmission to the stock market. The proposed model is able to circumvent the path dependency problem that can influence the prediction’s robustness and can provide useful information for investors and government agencies that have largely based their views on the notion that crude oil markets affect negatively stock market returns. Second, under the hypothesis of common increased volatility, we investigate whether these states happen around the identified international crises. Indeed, the results show that the A Haar Trous Wavelet decomposition method appears to be an important step toward improving accuracy of the smooth signal in detecting key real crude oil volatility features. Additionally

Ultrafast growth of wadsleyite in shock-produced melts and its implications for early solar system impact processes

Energy Technology Data Exchange (ETDEWEB)

Tschauner, Oliver; Asimow, Paul; Kostandova, Natalia; Ahrens, Thomas; Ma, Chi; Sinogeikin, Stanislav; Liu, Zhenxian; Fakra, Sirine; Tamura, Nobumichi

2009-12-01

We observed micrometer-sized grains of wadsleyite, a high-pressure phase of (Mg,Fe)2SiO4, in the recovery products of a shock experiment. We infer these grains crystallized from shock-generated melt over a time interval of <1 fs, the maximum time over which our experiment reached and sustained pressure sufficient to stabilize this phase. This rapid crystal growth rate (=1 m/s) suggests that, contrary to the conclusions of previous studies of the occurrence of high-pressure phases in shock-melt veins in strongly shocked meteorites, the growth of high-pressure phases from the melt during shock events is not diffusion-controlled. Another process, such as microturbulent transport, must be active in the crystal growth process. This result implies that the times necessary to crystallize the high-pressure phases in shocked meteorites may correspond to shock pressure durations achieved on impacts between objects 1-5 m in diameter and not, as previously inferred, =1-5 km in diameter. These results may also provide another pathway for syntheses, via shock recovery, of some high-value, high-pressure phases.

Cosmic-ray shock acceleration in oblique MHD shocks

Science.gov (United States)

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

1986-01-01

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

Microsoft Windows Sharepoint Services 3.0 Step by Step

CERN Document Server

Londer, Olga; Bleeker, Todd; Coventry, Penelope

2007-01-01

Experience learning made easy-and quickly teach yourself how to use Windows SharePoint Services to enable effective team collaboration. With Step By Step, you set the pace-building and practicing the skills you need, just when you need them! Build your own SharePoint site with easy-to-use templatesCreate lists and libraries to store informationAdd discussion boards, wikis, and blogsSet up Document and Meeting Workspaces for easy collaborationShare calendars, contacts, and data from Microsoft Office programsCustomize your pages with Web Parts Your all-in-one learning experience includes: Fi

Shock-to-detonation transition of RDX, HMX and NTO based composite high explosives: experiments and modelling

International Nuclear Information System (INIS)

Baudin, G; Roudot, M; Genetier, M; Mateille, P; Lefrançois, A

2014-01-01

HMX, RDX and NTO based cast-cured plastic bounded explosive (PBX) are widely used in insensitive ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside PBX. Comparing to a pressed PBX, a cast-cured PBX is not porous and the hot-spots are mainly located at the grain-binder interface leading to a different burning behavior during shock-to-detonation transition. Here, we review the shock-to-detonation transition (SDT) and its modeling for cast-cured PBX containing HMX, RDX and NTO. Future direction is given in conclusion.

Shock-to-detonation transition of RDX, HMX and NTO based composite high explosives: experiments and modelling

Science.gov (United States)

Baudin, G.; Roudot, M.; Genetier, M.; Mateille, P.; Lefrançois, A.

2014-05-01

HMX, RDX and NTO based cast-cured plastic bounded explosive (PBX) are widely used in insensitive ammunitions. Designing modern warheads needs robust and reliable models to compute shock ignition and detonation propagation inside PBX. Comparing to a pressed PBX, a cast-cured PBX is not porous and the hot-spots are mainly located at the grain-binder interface leading to a different burning behavior during shock-to-detonation transition. Here, we review the shock-to-detonation transition (SDT) and its modeling for cast-cured PBX containing HMX, RDX and NTO. Future direction is given in conclusion.

Effective Shear Viscosity of Iron under Shock-Loading Condition

International Nuclear Information System (INIS)

Ma Xiao-Juan; Liu Fu-Sheng; Sun Yan-Yun; Zhang Ming-Jian; Peng Xiao-Juan; Li Yong-Hong

2011-01-01

We combine the flyer-impact experiment and improve the finite difference method to solve whether the shear viscosity coefficient of shock iron is more reliable. We find that the numerical simulated profile agrees well with the measured one, from which the determined effective shear viscosity coefficients of shocked iron are 3000 ± 100 Pa·s and 4000 ± 100 Pa·s, respectively, at 103 GPa and 159 GPa. These values are more than 2000 ± 300 Pa·s of Li Y L et al.[Chin. Phys. Lett. 26 (2009) 038301] Our values are more reasonable because they are obtained from a comprehensive simulation for the full-shocked perturbation evolving process. (fundamental areas of phenomenology(including applications))

Phase transition in a shock loaded 304 stainless steel

International Nuclear Information System (INIS)

Naulin, G.

1989-11-01

Systematic shock recovery experiments have been performed on a Z2 CN 18-10 stainless steel (304 AISI), shocked in a pressure range of 5-13 GPa. The pulse durations lay between 0.1 μs and 2 μs. The phases transformation γ (fcc) to α' (bcc) is studied. The evolution of microstructures, the nucleation and the coalescence of α' phase embryos have been observed by TEM examinations. Quantitative measurements of the α' phase allow to plot diagrams of transformed phase versus shock pressure and pulse duration. Manganin gages allow to know the pressure evolution during the impact. The Olson and Cohen model describes the development of the α' phase versus the plastic deformation. An adaptation of this model has been developed, which describes the development of the α' phase versus shock pressure and pulse duration. Theoretical laws give a good correlation with experimental results [fr

DSMC Computations for Regions of Shock/Shock and Shock/Boundary Layer Interaction

Science.gov (United States)

Moss, James N.

2001-01-01

This paper presents the results of a numerical study of hypersonic interacting flows at flow conditions that include those for which experiments have been conducted in the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel and the ONERA R5Ch low-density wind tunnel. The computations are made with the direct simulation Monte Carlo (DSMC) method of Bird. The focus is on Mach 9.3 to 11.4 flows about flared axisymmetric configurations, both hollow cylinder flares and double cones. The results presented highlight the sensitivity of the calculations to grid resolution, provide results concerning the conditions for incipient separation, and provide information concerning the flow structure and surface results for the extent of separation, heating, pressure, and skin friction.

Extracorporeal shock wave lithotripsy for gallbladder stones - an experimental and clinical study -

International Nuclear Information System (INIS)

Kim, Kun Sang; Park, Sil Moo; Lee, Jung Hyo; Kim, Young Goo; Song, Kounn Sik; Lee, Kwan Seh; Lee, Jong Beum; Kim, Sang Joon; Chang, Sun Taik

1988-01-01

Although many alternative treatment technics have been proposed recently for gallstone to substitute cholecystectomy, the extracorporeal shock wave lithotripsy (ESWL) for gallbladder stones has rarely been tried. We have carried out a series of experiments to evaluate how effective the ESWL for gallbladder stones in and how safe this procedure is. At first, in vitro shock were application was carried out to 10 gallbladder stones which were obtained from human gallbladder. Secondly, gallbladder stones were implanted to canine gallbladder and treated with shock wave. Lastly, a total of 41 volunteers with confirmed gallbladder stones were treated with shock wave and combined oral administration of ursodeoxycholic acid. In the in vitro experiment, all of the 10 gallstones were fragmented with variable firing rates and duration. In animal experiment, the implanted stones were successfully fragmented and the organs included in the pathway of shock wave were proved to be intact histologically. In human study, complete disappearance of gallstones was noted in 78.6% of patients with single radiolucent gallbladder stones, smaller than 2.5cm in the longest diameter. Two patients underwent cholecystectomy after ESWL due to sudden colic attack. One patient had experienced an episode of mild transient obstructive jaundice. It may be concluded that the ESWL for gallbladder stones is an effective and safe method of treatment of gallbladder stones in the selected cases, for example, small radiolucent stones, and the further study is needed to establish improved technology of the ESWL for gallbladder stones.

Extracorporeal shock wave lithotripsy for gallbladder stones - an experimental and clinical study -

Energy Technology Data Exchange (ETDEWEB)

Kim, Kun Sang; Park, Sil Moo; Lee, Jung Hyo; Kim, Young Goo; Song, Kounn Sik; Lee, Kwan Seh; Lee, Jong Beum; Kim, Sang Joon; Chang, Sun Taik [Chung-Ang University College of Medicine, Seoul (Korea, Republic of)

1988-08-15

Although many alternative treatment technics have been proposed recently for gallstone to substitute cholecystectomy, the extracorporeal shock wave lithotripsy (ESWL) for gallbladder stones has rarely been tried. We have carried out a series of experiments to evaluate how effective the ESWL for gallbladder stones in and how safe this procedure is. At first, in vitro shock were application was carried out to 10 gallbladder stones which were obtained from human gallbladder. Secondly, gallbladder stones were implanted to canine gallbladder and treated with shock wave. Lastly, a total of 41 volunteers with confirmed gallbladder stones were treated with shock wave and combined oral administration of ursodeoxycholic acid. In the in vitro experiment, all of the 10 gallstones were fragmented with variable firing rates and duration. In animal experiment, the implanted stones were successfully fragmented and the organs included in the pathway of shock wave were proved to be intact histologically. In human study, complete disappearance of gallstones was noted in 78.6% of patients with single radiolucent gallbladder stones, smaller than 2.5cm in the longest diameter. Two patients underwent cholecystectomy after ESWL due to sudden colic attack. One patient had experienced an episode of mild transient obstructive jaundice. It may be concluded that the ESWL for gallbladder stones is an effective and safe method of treatment of gallbladder stones in the selected cases, for example, small radiolucent stones, and the further study is needed to establish improved technology of the ESWL for gallbladder stones.

Iron Damage and Spalling Behavior below and above Shock Induced α ε Phase Transition

International Nuclear Information System (INIS)

Voltz, Christophe; Buy, Francois; Roy, Gilles

2006-01-01

The study of dynamic damage and fracture of iron has been undertaken below and above phase transition by series of time resolved experiments using both light gas launcher and powder gun. Shock wave tests were conducted by symmetrical impacts of high purity iron. To reveal the material behavior we have done shock experiments where the target is covered with a window in order to limit release amplitude and to avoid specimen fragmentation. Metallurgical analysis of soft recovered samples yields information about damage and fracture processes related to thermo-mechanical loading paths. Tests conducted without window allow studying effects of both phase change and release transition. Optical and SEM characterizations lead us to observe several modes of damage: brittle, ductile diffuse with void growth and heavily localized smooth one. These figures are related with: rarefaction shock waves or interfaces between transformed and not transformed iron. Simulations are performed with the 1D to compare experimental data with numerical results. We explain post-mortem observations by the complex shock wave structure interactions: P1 and P2 shock fronts associated with some corresponding shock release during unloading stages

Orientation dependence of shock-induced twinning and substructures in a copper bicrystal

International Nuclear Information System (INIS)

Cao Fang; Beyerlein, Irene J.; Addessio, Francis L.; Sencer, Bulent H.; Trujillo, Carl P.; Cerreta, Ellen K.; Gray, George T. III

2010-01-01

Shock recovery experiments have been conducted to assess the role of shock stress and orientation dependence on substructure evolution and deformation twinning of a [1 0 0]/[011-bar] copper bicrystal. Transmission electron microscopy of the post-shock specimens revealed that well-defined dislocation cell structures developed in both grains and the average cell size decreased with increasing shock pressure from 5 to 10 GPa. Twinning occurred in the [1 0 0] grain, but not the [011-bar] grain, at the 10 GPa shock pressure. The stress and orientation dependence of incipient twinning can be predicted by the stress and orientation conditions required to dissociate slip dislocations into glissile twinning dislocations. The dynamic widths between the two partials are calculated considering the three-dimensional deviatoric stress state induced by the shock as calculated using plane-strain plate impact simulations and the relativistic and drag effects on dislocations moving at high speeds.

Gas-gun facility for shock wave research at BARC

International Nuclear Information System (INIS)

Gupta, S.C.; Jyoti, G.; Suresh, N.; Sikka, S.K.; Chidambaram, R.; Agarwal, R.G.; Roy, S.; Kakodkar, A.

1995-01-01

For carrying out shock-wave experiments on materials, we have built a 63 mm diameter gas-gun facility at our laboratory. It is capable of accelerating projectiles (about half kg in weight) to velocities up to 1 km/s using N 2 and He gases. These on impacting a target generate shock pressures up to 40 GPa, depending upon the impedance of the impactor and the target. The barrel of the gun is slotted so that a keyed projectile can be fired for combined compression- shear studies. Large samples can be shocked (about 60 mm diameter and 5-10 mm thick), with pressures lasting for a few microseconds. The gun is similar in design to the one at Washington State University. A number of diagnostic techniques have also been developed. These include measurement of projectile velocity, tilt between the impactor and the target, shock velocity in the target, and time resolved in-material stress wave histories in the shock loaded samples. Recovery capsules have also been made to retrieve shocked samples on unloading, which are then analysed using microscopic techniques like x-ray diffraction, Raman and electron microscopy. The gun has been performing well and has already been used for a few phase transition studies. (author). 73 refs., 42 figs

Income Shocks and Adolescent Mental Health

Science.gov (United States)

Baird, Sarah; de Hoop, Jacobus; Ozler, Berk

2013-01-01

We investigate the effects of a positive income shock on mental health among adolescent girls using evidence from a cash transfer experiment in Malawi. Offers of cash transfers strongly reduced psychological distress among baseline schoolgirls. However, these large beneficial effects declined with increases in the transfer amount offered to the…

Violent flows in aqueous foams III: physical multi-phase model comparison with aqueous foam shock tube experiments

Science.gov (United States)

Redford, J. A.; Ghidaglia, J.-M.; Faure, S.

2018-06-01

Mitigation of blast waves in aqueous foams is a problem that has a strong dependence on multi-phase effects. Here, a simplified model is developed from the previous articles treating violent flows (D'Alesio et al. in Eur J Mech B Fluids 54:105-124, 2015; Faure and Ghidaglia in Eur J Mech B Fluids 30:341-359, 2011) to capture the essential phenomena. The key is to have two fluids with separate velocities to represent the liquid and gas phases. This allows for the interaction between the two phases, which may include terms for drag, heat transfer, mass transfer due to phase change, added mass effects, to be included explicitly in the model. A good test for the proposed model is provided by two experimental data sets that use a specially designed shock tube. The first experiment has a test section filled with spray droplets, and the second has a range of aqueous foams in the test section. A substantial attenuation of the shock wave is seen in both cases, but a large difference is observed in the sound speeds. The droplets cause no observable change from the air sound speed, while the foams have a reduced sound speed of approximately 50-75 m/s . In the model given here, an added mass term is introduced in the governing equations to capture the low sound speed. The match between simulation and experiment is found to be satisfactory for both droplets and the foam. This is especially good when considering the complexity of the physics and the effects that are unaccounted for, such as three-dimensionality and droplet atomisation. The resulting statistics illuminate the processes occurring in such flows.

Shock compression of nitrobenzene; Nitoro benzen no shogeki asshoku

Energy Technology Data Exchange (ETDEWEB)

Kozu, Naoshi; Arai, Mitsuru; Tamura, Masamitsu [The University of Tokyo, Tokyo (Japan). Department of Chemical System Engineering; Yoshida, Masatake [National Institute of Materials and Chemical Research, Tsukuba (Japan)

1999-08-31

The Hugoniot (4 - 30 x 10{sup 9}Pa) of nitrobenzene has been obtained by shock compression experiments. Explosive plane-wae generators were used for plane shock wave generation. The obtained Hugoniot consists of two linear lines (U{sub s} (x 10{sup 3}m/s) = 2.52 + 1.23U{sub p} (x 10{sup 3}m/s)(0.8experiments of shock compression of nitrobenzene. (author)

Shock Producers and Shock Absorbers in the Crisis

OpenAIRE

Sinn, Hans-Werner

2009-01-01

It is not surprising that the U.S. has been by far the world’s largest shock producer in this crisis. The big shock absorbers on the other hand were Japan, Russia and Germany, whose exports shrank more than their imports.

Theory of the corrugation instability of a piston-driven shock wave.

Science.gov (United States)

Bates, J W

2015-01-01

We analyze the two-dimensional stability of a shock wave driven by a steadily moving corrugated piston in an inviscid fluid with an arbitrary equation of state. For h≤-1 or h>h(c), where h is the D'yakov parameter and h(c) is the Kontorovich limit, we find that small perturbations on the shock front are unstable and grow--at first quadratically and later linearly--with time. Such instabilities are associated with nonequilibrium fluid states and imply a nonunique solution to the hydrodynamic equations. The above criteria are consistent with instability limits observed in shock-tube experiments involving ionizing and dissociating gases and may have important implications for driven shocks in laser-fusion, astrophysical, and/or detonation studies.

A polar-drive shock-ignition design for the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Anderson, K. S.; McKenty, P. W.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Marozas, J. A.; Skupsky, S.; Shvydky, A. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Betti, R. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States); Departments of Mechanical Engineering and Physics, University of Rochester, Rochester, New York 14627 (United States); Hohenberger, M.; Theobald, W.; Lafon, M.; Nora, R. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Fusion Science Center, University of Rochester, Rochester, New York 14623 (United States)

2013-05-15

Shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)] is being pursued as a viable option to achieve ignition on the National Ignition Facility (NIF). Shock-ignition target designs use a high-intensity laser spike at the end of a low-adiabat assembly pulse to launch a spherically convergent strong shock to ignite the hot spot of an imploding capsule. A shock-ignition target design for the NIF is presented. One-dimensional simulations indicate an ignition threshold factor of 4.1 with a gain of 58. A polar-drive beam-pointing configuration for shock-ignition experiments on the NIF at 750 kJ is proposed. The capsule design is shown to be robust to the various one- and two-dimensional effects and nonuniformities anticipated on the NIF. The target is predicted to ignite with a gain of 38 when including all anticipated levels of nonuniformity and system uncertainty.

Investigation of a Shock Absorber for Safeguard of Fuel Assemblies Failure

International Nuclear Information System (INIS)

Karalevicius, Renatas; Dundulis, Gintautas; Rimkevicius, Sigitas; Uspuras, Eugenijus

2006-01-01

The Ignalina NPP has two reactors. The Unit 1 was shut down, therefore the special equipment was designed for transportation of the fuel from Unit 1 to Unit 2. The fuel-loaded basket can drop during transportation. The special shock absorber was designed in order to avoid failure of fuel assemblies during transportation. In case of drop of fuel loaded basket, the failure of fuel assemblies can occur. This shock absorber was studied by scaled experiments at Lithuanian Energy Institute. Static and dynamic investigations of shock absorber are presented in this paper, including dependency of axial force versus axial compression. The finite element codes BRIGADE/Plus and ABAQUS/Explicit were used for analysis. Static simulation was used to optimize the dimensions of shock absorber. Dynamic analysis shows that shock absorber is capable to withstand the dynamic load for successful force suppression function in case of an accident. (authors)

Weibel instability mediated collisionless shocks using intense laser-driven plasmas

Science.gov (United States)

Palaniyappan, Sasikumar; Fiuza, Federico; Huang, Chengkun; Gautier, Donald; Ma, Wenjun; Schreiber, Jorg; Raymer, Abel; Fernandez, Juan; Shimada, Tom; Johnson, Randall

2017-10-01

The origin of cosmic rays remains a long-standing challenge in astrophysics and continues to fascinate physicists. It is believed that ``collisionless shocks'' - where the particle Coulomb mean free path is much larger that the shock transition - are a dominant source of energetic cosmic rays. These shocks are ubiquitous in astrophysical environments such as gamma-ray bursts, supernova remnants, pulsar wind nebula and coronal mass ejections from the sun. A particular type of electromagnetic plasma instability known as Weibel instability is believed to be the dominant mechanism behind the formation of these collisionless shocks in the cosmos. The understanding of the microphysics behind collisionless shocks and their particle acceleration is tightly related with nonlinear basic plasma processes and remains a grand challenge. In this poster, we will present results from recent experiments at the LANL Trident laser facility studying collisionless shocks using intense ps laser (80J, 650 fs - peak intensity of 1020 W/cm2) driven near-critical plasmas using carbon nanotube foam targets. A second short pulse laser driven protons from few microns thick gold foil is used to radiograph the main laser-driven plasma. Work supported by the LDRD program at LANL.

First results of transcritical magnetized collisionless shock studies on MSX

Science.gov (United States)

Weber, T. E.; Smith, R. J.; Hutchinson, T. M.; Taylor, S. F.; Hsu, S. C.

2014-10-01

Magnetized collisionless shocks exhibit transitional length and time scales much shorter than can be created through collisional processes. They are common throughout the cosmos, but have historically proven difficult to create in the laboratory. The Magnetized Shock Experiment (MSX) at LANL produces super-Alfvénic shocks through the acceleration and subsequent stagnation of Field Reversed Configuration (FRC) plasmoids against a strong magnetic mirror and flux-conserving vacuum boundary. Plasma flows have been produced with sonic and Alfvén Mach numbers up to ~10 over a wide range of plasma beta with embedded perpendicular, oblique, and parallel magnetic field. Macroscopic ion skin-depth and long ion-gyroperiod enable diagnostic access to relevant shock physics using common methods. Variable plasmoid velocity, density, temperature, and magnetic field provide access to a wide range of shock conditions, and a campaign to study the physics of transcritical and supercritical shocks within the FRC plasmoid is currently underway. An overview of the experimental design, diagnostics suite, physics objectives, and recent results will be presented. Supported by DOE Office of Fusion Energy Sciences under DOE Contract DE-AC52-06NA25369.

Shock Isolation Elements Testing for High Input Loadings. Volume II. Foam Shock Isolation Elements.

Science.gov (United States)

SHOCK ABSORBERS ), (*GUIDED MISSILE SILOS, SHOCK ABSORBERS ), (*EXPANDED PLASTICS, (*SHOCK(MECHANICS), REDUCTION), TEST METHODS, SHOCK WAVES, STRAIN(MECHANICS), LOADS(FORCES), MATHEMATICAL MODELS, NUCLEAR EXPLOSIONS, HARDENING.

Shock initiation of explosives: Temperature spikes and growth spurts

Science.gov (United States)

Bassett, Will P.; Dlott, Dana D.

2016-08-01

When energetic materials are subjected to high-velocity impacts, the first steps in the shock-to-detonation transition are the creation, ignition, and growth of hot spots. We used 1-3.2 km s-1 laser-launched flyer plates to impact powdered octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, a powerful explosive, and monitored hundreds of emission bursts with an apparatus that determined temperature and emissivity at all times. The time-dependent volume fraction of hot spots was determined by measuring the time-dependent emissivity. After the shock, most hot spots extinguished, but the survivors smoldered for hundreds of nanoseconds until their temperatures spiked, causing a hot spot growth spurt. Depending on the impact duration, the growth spurts could be as fast as 300 ns and as slow as 13 μs.

Laboratory studies of magnetized collisionless flows and shocks using accelerated plasmoids

Science.gov (United States)

Weber, T. E.; Smith, R. J.; Hsu, S. C.

2015-11-01

Magnetized collisionless shocks are thought to play a dominant role in the overall partition of energy throughout the universe, but have historically proven difficult to create in the laboratory. The Magnetized Shock Experiment (MSX) at LANL creates conditions similar to those found in both space and astrophysical shocks by accelerating hot (100s of eV during translation) dense (1022 - 1023 m-3) Field Reversed Configuration (FRC) plasmoids to high velocities (100s of km/s); resulting in β ~ 1, collisionless plasma flows with sonic and Alfvén Mach numbers of ~10. The FRC subsequently impacts a static target such as a strong parallel or anti-parallel (reconnection-wise) magnetic mirror, a solid obstacle, or neutral gas cloud to create shocks with characteristic length and time scales that are both large enough to observe yet small enough to fit within the experiment. This enables study of the complex interplay of kinetic and fluid processes that mediate cosmic shocks and can generate non-thermal distributions, produce density and magnetic field enhancements much greater than predicted by fluid theory, and accelerate particles. An overview of the experimental capabilities of MSX will be presented, including diagnostics, selected recent results, and future directions. Supported by the DOE Office of Fusion Energy Sciences under contract DE-AC52-06NA25369.

Reliability for systems of degrading components with distinct component shock sets

International Nuclear Information System (INIS)

Song, Sanling; Coit, David W.; Feng, Qianmei

2014-01-01

This paper studies reliability for multi-component systems subject to dependent competing risks of degradation wear and random shocks, with distinct shock sets. In practice, many systems are exposed to distinct and different types of shocks that can be categorized according to their sizes, function, affected components, etc. Previous research primarily focuses on simple systems with independent failure processes, systems with independent component time-to-failure, or components that share the same shock set or type of shocks. In our new model, we classify random shocks into different sets based on their sizes or function. Shocks with specific sizes or function can selectively affect one or more components in the system but not necessarily all components. Additionally the shocks from the different shock sets can arrive at different rates and have different relative magnitudes. Preventive maintenance (PM) optimization is conducted for the system with different component shock sets. Decision variables for two different maintenance scheduling problems, the PM replacement time interval, and the PM inspection time interval, are determined by minimizing a defined system cost rate. Sensitivity analysis is performed to provide insight into the behavior of the proposed maintenance policies. These models can be applied directly or customized for many complex systems that experience dependent competing failure processes with different component shock sets. A MEMS (Micro-electro mechanical systems) oscillator is a typical system subject to dependent and competing failure processes, and it is used as a numerical example to illustrate our new reliability and maintenance models

Dispersive shock waves in Bose-Einstein condensates and nonlinear nano-oscillators in ferromagnetic thin films

Science.gov (United States)

Hoefer, Mark A.

This thesis examines nonlinear wave phenomena, in two physical systems: a Bose-Einstein condensate (BEC) and thin film ferromagnets where the magnetization dynamics are excited by the spin momentum transfer (SMT) effect. In the first system, shock waves generated by steep gradients in the BEC wavefunction are shown to be of the disperse type. Asymptotic and averaging methods are used to determine shock speeds and structure in one spatial dimension. These results are compared with multidimensional numerical simulations and experiment showing good, qualitative agreement. In the second system, a model of magnetization dynamics due to SMT is presented. Using this model, nonlinear oscillating modes---nano-oscillators---are found numerically and analytically using perturbative methods. These results compare well with experiment. A Bose-Einstein condensate (BEC) is a quantum fluid that gives rise to interesting shock wave nonlinear dynamics. Experiments depict a BEC that exhibits behavior similar to that of a shock wave in a compressible gas, e.g. traveling fronts with steep gradients. However, the governing Gross-Pitaevskii (GP) equation that describes the mean field of a BEC admits no dissipation hence classical dissipative shock solutions do not explain the phenomena. Instead, wave dynamics with small dispersion is considered and it is shown that this provides a mechanism for the generation of a dispersive shock wave (DSW). Computations with the GP equation are compared to experiment with excellent agreement. A comparison between a canonical 1D dissipative and dispersive shock problem shows significant differences in shock structure and shock front speed. Numerical results associated with laboratory experiments show that three and two-dimensional approximations are in excellent agreement and one dimensional approximations are in qualitative agreement. The interaction of two DSWs is investigated analytically and numerically. Using one dimensional DSW theory it is argued

Gravitational shock waves and extreme magnetomaterial shock waves

International Nuclear Information System (INIS)

Lichnerowicz, Andre.

1975-01-01

Within an astrophysical context corresponding to high densities, a self-gravitating model is studied, which is the set of an extreme material medium of infinite conductivity and of a magnetic field. Corresponding shock waves generate necessarily, in general, gravitational shock waves [fr

Schedules of electric shock presentation in the behavioral control of imprinted ducklings.

Science.gov (United States)

Barrett, J E

1972-09-01

The behavioral effects of various schedules of electric shock presentation were investigated during and after the imprinting of Peking ducklings to moving stimuli. The behavior of following a moving imprinted stimulus was differentially controlled by a multiple schedule of punishment and avoidance that respectively suppressed and maintained following behavior. Pole-pecking, reinforced by presentations of the imprinted stimulus, was suppressed by response-produced shock (punishment); various schedules of response-independent shock and delayed punishment had an overall minimal effect. The delivery of response-independent shock in the presence of one of two stimuli, both during and after imprinting, resulted in a marked reduction in choice of the stimulus paired with shock. The experiments provide no support for a differentiation of imprinting from learning on the basis of the behavioral effects of aversive stimuli. Instead, as is the case with other organisms, the schedule under which shock is delivered to imprinted ducklings appears to be an important determinant of the temporal patterning of subsequent behavior.

Wound shock: a history of its study and treatment by military surgeons.

Science.gov (United States)

Hardaway, Robert M

2004-04-01

The treatment of wounds has received considerable attention from the time of the Trojan War. However, it was not until the American Civil War that shock was described as an entity distinct from the wounds themselves and that efforts were directed at more than just treatment of the wound. The need for fluid resuscitation in the treatment of hemorrhagic shock was first recognized in the Spanish American War, as was the association of sepsis with shock. World War I showed the need for blood in the treatment of "wound shock," a lesson that had to be relearned in World War II through bitter experience. Studies in the Korean War described the concept of disseminated intravascular coagulation and multiple organ failure, and the existence of disseminated intravascular coagulation was confirmed by studies in Vietnam. The treatment of hemorrhagic shock is now very effective, but the treatment of traumatic and septic shock remains unsatisfactory.

Yield strength measurement of shock-loaded metal by flyer-impact perturbation method

Science.gov (United States)

Ma, Xiaojuan; Shi, Zhan

2018-06-01

Yield strength is one of the most important physical properties of a solid material, especially far from its melting line. The flyer-impact perturbation method measures material yield strength on the basis of correlation between the yield strength under shock compression and the damping of oscillatory perturbations in the shape of a shock front passing through the material. We used flyer-impact experiments on targets with machined grooves on the impact surface of shock 6061-T6 aluminum to between 32 and 61 GPa and recorded the evolution of the shock front perturbation amplitude in the sample with electric pins. Simulations using the elastic-plastic model can be matched to the experiments, explaining well the form of the perturbation decay and constraining the yield strength of 6061-T6 aluminum to be 1.31-1.75 GPa. These results are in agreement with values obtained from reshock and release wave profiles. We conclude that the flyer-impact perturbation method is indeed a new means to measure material strength.

Selective release of D and 13C from insoluble organic matter of the Murchison meteorite by impact shock

Science.gov (United States)

Mimura, Koichi; Okamoto, Michioki; Sugitani, Kenichiro; Hashimoto, Shigemasa

2007-03-01

We performed shock-recovery experiments on insoluble organic matter (IOM) purified from the Murchison meteorite, and determined the abundances and isotope ratios of hydrogen and carbon in the shocked IOM sample. We also performed shock experiments on type III kerogen and compared the results of these experiments with the experimental results regarding IOM.The shock selectively released D and 13C from the IOM, while it preferably released H and 12C from the kerogen. The release of these elements from IOM cannot be explained in terms of the isotope effect, whereas their release from kerogen can be explained by this effect. The selective release of heavier isotopes from IOM would be due to its structure, in which D and 13C-enriched parts are present as an inhomogeneity and are weakly attached to the main network. Shock gave rise to a high release of D even at a lower degree of dehydrogenation compared with the stepwise heating of IOM. This effective release of D is probably an inherent result of shock, in which a dynamic high-pressure and high-temperature condition prevails. Thus, shock would effectively control the hydrogen isotope behavior of extraterrestrial organic matter during the evolution of the solar nebula.

A model for precursor structure in supercritical perpendicular, collisionless shock waves

International Nuclear Information System (INIS)

Sherwell, D.; Cairns, R.A.

1978-01-01

Magnetosonic solitons may be given smooth increasing profiles by assuming the presence within the wave of a current distribution Jsub(y)(x) of trapped ions perpendicular to Bsub(z)(x) and the wave velocity Vsub(x). Suitable ions are found immediately upstream of perpendicular collisionless shock waves and these are coincident with the often observed 'foot' in magnetic field profiles of moderately supercritical shocks. The theory is applied to previous experiments by modelling Jsub(y)(x), where Jsub(y)(x) is observed, the profiles in the foot are reproduced and explained. Insight into a number of features of fast shocks is obtained. (author)

Quasilinear simulations of interplanetary shocks and Earth's bow shock

Science.gov (United States)

Afanasiev, Alexandr; Battarbee, Markus; Ganse, Urs; Vainio, Rami; Palmroth, Minna; Pfau-Kempf, Yann; Hoilijoki, Sanni; von Alfthan, Sebastian

2016-04-01

We have developed a new self-consistent Monte Carlo simulation model for particle acceleration in shocks. The model includes a prescribed large-scale magnetic field and plasma density, temperature and velocity profiles and a self-consistently computed incompressible ULF foreshock under the quasilinear approximation. Unlike previous analytical treatments, our model is time dependent and takes full account of the anisotropic particle distributions and scattering in the wave-particle interaction process. We apply the model to the problem of particle acceleration at traveling interplanetary (IP) shocks and Earth's bow shock and compare the results with hybrid-Vlasov simulations and spacecraft observations. A qualitative agreement in terms of spectral shape of the magnetic fluctuations and the polarization of the unstable mode is found between the models and the observations. We will quantify the differences of the models and explore the region of validity of the quasilinear approach in terms of shock parameters. We will also compare the modeled IP shocks and the bow shock, identifying the similarities and differences in the spectrum of accelerated particles and waves in these scenarios. The work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA). The Academy of Finland is thanked for financial support. We acknowledge the computational resources provided by CSC - IT Centre for Science Ltd., Espoo.

Nanosecond (ns) laser transfer of silver nanoparticles from silver-exchanged soda-lime glass to transparent soda-lime glass and shock waves formation

International Nuclear Information System (INIS)

Sow, Mohamed Chérif; Blondeau, Jean-Philippe; Sagot, Nadine; Ollier, Nadège; Tite, Teddy

2015-01-01

Highlights: • Silver nanoparticles growth by nanosecond laser irradiation of silver exchanged soda-lime glasses. • Silver nanoparticles transfer. • Nanosecond laser induced shock waves formation on glass. - Abstract: In this contribution, we showed for the first time in our knowledge a single-step process for silver clusters and nanoparticles growth and transfer from silver-exchanged soda-lime glass to un-exchanged soda-lime glass (transparent glass in visible and NIR domain) by nanosecond (ns) laser irradiation. The transferred silver nanoparticles in transparent glass are strongly linked to the glass surface. In addition, we point out the formation of shock waves, with selective silver clustering on the top wave. This technique provides an alternative and simple way to obtain metallic nanoparticles in different media which can be traversed by laser wavelength used. Moreover, this experiment is made at room temperature and air environment. It is worth noting that our technique requires a glass previously doped with the corresponding silver ions

Multiple spacecraft observations of interplanetary shocks Four spacecraft determination of shock normals

Science.gov (United States)

Russell, C. T.; Mellott, M. M.; Smith, E. J.; King, J. H.

1983-01-01

ISEE 1, 2, 3, IMP 8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for future investigations these data allow the evaluation of the accuracy of several shock normal determination techniques. When the angle between upstream and downstream magnetic field is greater than 20 deg, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, the use of overdetermined shock normal solutions, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints, is recommended whenever possible.

Micro-Ramp Flow Control for Oblique Shock Interactions: Comparisons of Computational and Experimental Data

Science.gov (United States)

Hirt, Stephanie M.; Reich, David B.; O'Connor, Michael B.

2012-01-01

Computational fluid dynamics was used to study the effectiveness of micro-ramp vortex generators to control oblique shock boundary layer interactions. Simulations were based on experiments previously conducted in the 15- by 15-cm supersonic wind tunnel at the NASA Glenn Research Center. Four micro-ramp geometries were tested at Mach 2.0 varying the height, chord length, and spanwise spacing between micro-ramps. The overall flow field was examined. Additionally, key parameters such as boundary-layer displacement thickness, momentum thickness and incompressible shape factor were also examined. The computational results predicted the effects of the microramps well, including the trends for the impact that the devices had on the shock boundary layer interaction. However, computing the shock boundary layer interaction itself proved to be problematic since the calculations predicted more pronounced adverse effects on the boundary layer due to the shock than were seen in the experiment.

Success and failure of the defibrillation shock: insights from a simulation study.

Science.gov (United States)

Skouibine, K; Trayanova, N; Moore, P

2000-07-01

This simulation study presents a further inquiry into the mechanisms by which a strong electric shock fails to halt life-threatening cardiac arrhythmias. The research uses a model of the defibrillation process that represents a sheet of myocardium as a bidomain. The tissue consists of nonuniformly curved fibers in which spiral wave reentry is initiated. Monophasic defibrillation shocks are delivered via two line electrodes that occupy opposite tissue boundaries. In some simulation experiments, the polarity of the shock is reversed. Electrical activity in the sheet is compared for failed and successful shocks under controlled conditions. The maps of transmembrane potential and activation times calculated during and after the shock demonstrate that weak shocks fail to terminate the reentrant activity via two major mechanisms. As compared with strong shocks, weak shocks result in (1) smaller extension of refractoriness in the areas depolarized by the shock, and (2) slower or incomplete activation of the excitable gap created by deexcitation of the negatively polarized areas. In its turn, mechanism 2 is associated with one or more of the following events: (a) lack of some break excitations, (b) latency in the occurrence of the break excitations, and (c) slower propagation through deexcited areas. Reversal of shock polarity results in a change of the extent of the regions of deexcitation, and thus, in a change in defibrillation threshold. The results of this study indicate the paramount importance of shock-induced deexcitation in both defibrillation and postshock arrhythmogenesis.

Vorticity generation and evolution in shock-accelerated density-stratified interfaces

International Nuclear Information System (INIS)

Yang, X.; Chern, I.; Zabusky, N.J.; Samtaney, R.; Hawley, J.F.

1992-01-01

The results of direct numerical simulations of inviscid planar shock-accelerated density-stratified interfaces in two dimensions are presented and compared with shock tube experiments of Haas [(private communication, 1988)] and Sturtevant [in Shock Tubes and Waves, edited by H. Gronig (VCH, Berlin, 1987), p. 89] . Heavy-to-light (''slow/fast or s/f) and light-to-heavy (''fast/slow,'' or f/s) gas interfaces are examined and early-time impulsive vorticity deposition and the evolution of coherent vortex structures are emphasized and quantified. The present second-order Godunov scheme yields excellent agreement with shock-polar analyses at early time. A more physical vortex interpretation explains the commonly used (i.e., linear paradigm) designations of ''unstable'' and ''stable'' for the f/s and s/f interfaces, respectively. The later time events are Rayleigh--Taylor like and can be described in terms of the evolution of a vortex layer (large-scale translation and rotation): asymmetric tip vortex ''roll-up'' and ''binding;'' layer ''instability;'' convective mixing; and baroclinic vorticity generation from secondary shock--interface interactions

Are Credit Shocks Supply or Demand Shocks?

OpenAIRE

Bijapur, Mohan

2013-01-01

This paper provides new insights into the relationship between the supply of credit and the macroeconomy. We present evidence that credit shocks constitute shocks to aggregate supply in that they have a permanent effect on output and cause inflation to rise in the short term. Our results also suggest that the effects on aggregate supply have grown stronger in recent decades.

Miniature shock tube for laser driven shocks.

Science.gov (United States)

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

2010-02-01

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

Optimal Design and Model Validation for Combustion Experiments in a Shock Tube

KAUST Repository

Long, Quan; Kim, Daesang; Tempone, Raul; Bisetti, Fabrizio; Farooq, Aamir; Knio, Omar; Prudhomme, Serge

2014-01-01

in the reaction rate functions. The control parameters are the initial hydrogen concentration and the temperature. First, we build a polynomial based surrogate model for the observable related to the reactions in the shock tube. Second, we use a novel MAP based

A new apparatus to induce lysis of planktonic microbial cells by shock compression, cavitation and spray

Science.gov (United States)

Schiffer, A.; Gardner, M. N.; Lynn, R. H.; Tagarielli, V. L.

2017-03-01

Experiments were conducted on an aqueous growth medium containing cultures of Escherichia coli (E. coli) XL1-Blue, to investigate, in a single experiment, the effect of two types of dynamic mechanical loading on cellular integrity. A bespoke shock tube was used to subject separate portions of a planktonic bacterial culture to two different loading sequences: (i) shock compression followed by cavitation, and (ii) shock compression followed by spray. The apparatus allows the generation of an adjustable loading shock wave of magnitude up to 300 MPa in a sterile laboratory environment. Cultures of E. coli were tested with this apparatus and the spread-plate technique was used to measure the survivability after mechanical loading. The loading sequence (ii) gave higher mortality than (i), suggesting that the bacteria are more vulnerable to shear deformation and cavitation than to hydrostatic compression. We present the results of preliminary experiments and suggestions for further experimental work; we discuss the potential applications of this technique to sterilize large volumes of fluid samples.

Effect of target-fixture geometry on shock-wave compacted copper powders

Science.gov (United States)

Kim, Wooyeol; Ahn, Dong-Hyun; Yoon, Jae Ik; Park, Lee Ju; Kim, Hyoung Seop

2018-01-01

In shock compaction with a single gas gun system, a target fixture is used to safely recover a powder compact processed by shock-wave dynamic impact. However, no standard fixture geometry exists, and its effect on the processed compact is not well studied. In this study, two types of fixture are used for the dynamic compaction of hydrogen-reduced copper powders, and the mechanical properties and microstructures are investigated using the Vickers microhardness test and electron backscatter diffraction, respectively. With the assistance of finite element method simulations, we analyze several shock parameters that are experimentally hard to control. The results of the simulations indicate that the target geometry clearly affects the characteristics of incident and reflected shock waves. The hardness distribution and the microstructure of the compacts also show their dependence on the geometry. With the results of the simulations and the experiment, it is concluded that the target geometry affects the shock wave propagation and wave interaction in the specimen.

Hydrodynamic modelling of the shock ignition scheme for inertial confinement fusion

International Nuclear Information System (INIS)

Vallet, Alexandra

2014-01-01

The shock ignition concept in inertial confinement fusion uses an intense power spike at the end of an assembly laser pulse. The key features of shock ignition are the generation of a high ablation pressure, the shock pressure amplification by at least a factor of a hundred in the cold fuel shell and the shock coupling to the hot-spot. In this thesis, new semi-analytical hydrodynamic models are developed to describe the ignitor shock from its generation up to the moment of fuel ignition. A model is developed to describe a spherical converging shock wave in a pre-heated hot spot. The self-similar solution developed by Guderley is perturbed over the shock Mach number Ms ≥≥1. The first order correction accounts for the effects of the shock strength. An analytical ignition criterion is defined in terms of the shock strength and the hot-spot areal density. The ignition threshold is higher when the initial Mach number of the shock is lower. A minimal shock pressure of 20 Gbar is needed when it enters the hot-spot. The shock dynamics in the imploding shell is then analyzed. The shock is propagating into a non inertial medium with a high radial pressure gradient and an overall pressure increase with time. The collision with a returning shock coming from the assembly phase enhances further the ignitor shock pressure. The analytical theory allows to describe the shock pressure and strength evolution in a typical shock ignition implosion. It is demonstrated that, in the case of the HiPER target design, a generation shock pressure near the ablation zone on the order of 300-400 Mbar is needed. An analysis of experiments on the strong shock generation performed on the OMEGA laser facility is presented. It is shown that a shock pressure close to 300 Mbar near the ablation zone has been reached with an absorbed laser intensity up to 2 * 10 15 W:cm -2 and a laser wavelength of 351 nm. This value is two times higher than the one expected from collisional laser absorption only

Experimental study of fast electron transport and of the propagation of shock waves generated by laser in the framework of inertial fusion

International Nuclear Information System (INIS)

Sakaki, T.

2016-01-01

This document presents 3 experiments carried out within the framework of inertial fusion. The first experiment was devoted to the study of fast electron beam transport in a compressed target. The implosion of the target with a cylindrical geometry was carried out with the GEKKO XII laser facility (ILE Osaka, Japan). The fast electron beam was generated by the LFEX laser (∼10"1"9 W/cm"2) and its propagation through the compressed cylinder was observed with several X-ray diagnostics. This experiment showed the guiding effect of the electron beam resulting from self-generated magnetic fields. Furthermore, the results of this experiment were in good agreement with numerical simulations. Two other experiments were performed to study the propagation of strong shock waves created by lasers in a plasma. They were carried out with different laser systems. In the first experiment with the Gekko XII laser, we observed the creation and the propagation of two successive shock waves in an ablation plasma in CH and Be. The objective of characterizing the amplification of a transmitted shock by the collision of two counter-propagating shocks has been partially realized. The comparison of the experimental results with the hydrodynamic simulations enabled us to confirm an amplification of the shock by a factor 2 in pressure in the condition of this experiment. The shot with a Be target allowed the development and validation of the diagnostic method of X-ray radiography for shock wave propagation. The second experiment was performed with PHELIX GSI laser (Darmstadt, Germany). The purpose of this experiment was to study the generation of strong shocks. They were applied to study the equation of state of carbon in the WDM state. The condition of pressure and density for the carbon were obtained by deducing the pressure and the velocity of the shock wave chronometric diagnostics employed in this experiment. In this experiment, diamond was at the metallic liquid phase with a pressure

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

Energy Technology Data Exchange (ETDEWEB)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Hohenberger, M.; Boehly, T. R. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Nikroo, A. [General Atomics, San Diego, California 92196 (United States)

2014-02-15

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2014-02-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

International Nuclear Information System (INIS)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J.; Hohenberger, M.; Boehly, T. R.; Nikroo, A.

2014-01-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing

Radiation- and pair-loaded shocks

Science.gov (United States)

Lyutikov, Maxim

2018-06-01

We consider the structure of mildly relativistic shocks in dense media, taking into account the radiation and pair loading, and diffusive radiation energy transfer within the flow. For increasing shock velocity (increasing post-shock temperature), the first important effect is the efficient energy redistribution by radiation within the shock that leads to the appearance of an isothermal jump, whereby the flow reaches the final state through a discontinuous isothermal transition. The isothermal jump, on scales much smaller than the photon diffusion length, consists of a weak shock and a quick relaxation to the isothermal conditions. Highly radiation-dominated shocks do not form isothermal jump. Pair production can mildly increase the overall shock compression ratio to ≈10 (4 for matter-dominated shocks and 7 of the radiation-dominated shocks).

Thermal Shock Property of Al／Ni-ZrO2 Gradient Thermal Barrier Coatings

Institute of Scientific and Technical Information of China (English)

FANJin-juan; WANGQuan-sheng; ZHANGWei-fang

2004-01-01

Al/Ni-ZrO2 gradient thermal barrier coatings are made on aluminum substrate using plasma spraying method and one direction thermal shock properties of the coatings are studied in this paper. The results show that pores in coatings link to form cracks vertical to coating surface. They go through the whole ZrO2 coating once vertical cracks form. When thermal shock cycles increase, horizontal cracks that result in coatings failure forms in the coatings and interface. And vertical cracks delay appearance of horizontal cracks and enhance thermal shock property of coatings. Failure mechanisms of coating thermal shock are discussed using experiments and finite element method.

Crowdsourcing step-by-step information extraction to enhance existing how-to videos

OpenAIRE

Nguyen, Phu Tran; Weir, Sarah; Guo, Philip J.; Miller, Robert C.; Gajos, Krzysztof Z.; Kim, Ju Ho

2014-01-01

Millions of learners today use how-to videos to master new skills in a variety of domains. But browsing such videos is often tedious and inefficient because video player interfaces are not optimized for the unique step-by-step structure of such videos. This research aims to improve the learning experience of existing how-to videos with step-by-step annotations. We first performed a formative study to verify that annotations are actually useful to learners. We created ToolScape, an interac...

INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

Directory of Open Access Journals (Sweden)

P. V. Bulat

2015-05-01

Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

Shock/shock interactions between bodies and wings

Directory of Open Access Journals (Sweden)

Gaoxiang XIANG

2018-02-01

Full Text Available This paper examines the Shock/Shock Interactions (SSI between the body and wing of aircraft in supersonic flows. The body is simplified to a flat wedge and the wing is assumed to be a sharp wing. The theoretical spatial dimension reduction method, which transforms the 3D problem into a 2D one, is used to analyze the SSI between the body and wing. The temperature and pressure behind the Mach stem induced by the wing and body are obtained, and the wave configurations in the corner are determined. Numerical validations are conducted by solving the inviscid Euler equations in 3D with a Non-oscillatory and Non-free-parameters Dissipative (NND finite difference scheme. Good agreements between the theoretical and numerical results are obtained. Additionally, the effects of the wedge angle and sweep angle on wave configurations and flow field are considered numerically and theoretically. The influences of wedge angle are significant, whereas the effects of sweep angle on wave configurations are negligible. This paper provides useful information for the design and thermal protection of aircraft in supersonic and hypersonic flows. Keywords: Body and wing, Flow field, Hypersonic flow, Shock/shock interaction, Wave configurations

Dynamic strength behavior of a Zr-based bulk metallic glass under shock loading

International Nuclear Information System (INIS)

Yu Yu-Ying; Xi Feng; Dai Cheng-Da; Cai Ling-Cang; Tan Ye; Li Xue-Mei; Wu Qiang; Tan Hua

2015-01-01

Dynamic strength behavior of Zr 51 Ti 5 Ni 10 Cu 25 Al 9 bulk metallic glass (BMG) up to 66 GPa was investigated in a series of plate impact shock-release and shock-reload experiments. Particle velocity profiles measured at the sample/LiF window interface were used to estimate the shear stress, shear modulus, and yield stress in shocked BMG. Beyond confirming the previously reported strain-softening of shear stress during the shock loading process for BMGs, it is also shown that the softened Zr-BMG still has a high shear modulus and can support large yield stress when released or reloaded from the shocked state, and both the shear modulus and the yield stress appear as strain-hardening behaviors. The work provides a much clearer picture of the strength behavior of BMGs under shock loading, which is useful to comprehensively understand the plastic deformation mechanisms of BMGs. (paper)

Modification of embryonic resistance to heat shock in cattle by melatonin and genetic variation in HSPA1L.

Science.gov (United States)

Ortega, M Sofia; Rocha-Frigoni, Nathália A S; Mingoti, Gisele Zoccal; Roth, Zvi; Hansen, Peter J

2016-11-01

The objectives were to test whether (1) melatonin blocks inhibition of embryonic development caused by heat shock at the zygote stage, and (2) the frequency of a thermoprotective allele for HSPA1L is increased in blastocysts formed from heat-shocked zygotes as compared with blastocysts from control zygotes. It was hypothesized that melatonin prevents effects of heat shock on development by reducing accumulation of reactive oxygen species (ROS) and that embryos inheriting the thermoprotective allele of HSPA1L would be more likely to survive heat shock. Effects of 1 µM melatonin on ROS were determined in experiments 1 and 2. Zygotes were cultured at 38.5 or 40°C for 3 h in the presence of CellROX reagent (ThermoFisher Scientific, Waltham, MA). Culture was in a low [5% (vol/vol)] oxygen (experiment 1) or low or high [21% (vol/vol)] oxygen environment (experiment 2). Heat shock and high oxygen increased ROS; melatonin decreased ROS. Development was assessed in experiments 3 and 4. In experiment 3, zygotes were cultured in low oxygen ± 1 µM melatonin and exposed to 38.5 or 40°C for 12 h (experiment 1) beginning 8 h after fertilization. Melatonin did not protect the embryo from heat shock. Experiment 4 was performed similarly except that temperature treatments (38.5 or 40°C, 24 h) were performed in a low or high oxygen environment (2×2 × 2 factorial design with temperature, melatonin, and oxygen concentration as main effects), and blastocysts were genotyped for a deletion (D) mutation (C→D) in the promoter region of HSPA1L associated with thermotolerance. Heat shock decreased percent of zygotes developing to the blastocyst stage independent of melatonin or oxygen concentration. Frequency of genotypes for HSPA1L was affected by oxygen concentration and temperature, with an increase in the D allele for blastocysts that developed in high oxygen and following heat shock. It was concluded that (1) lack of effect of melatonin or oxygen concentration on embryonic

STEREO interplanetary shocks and foreshocks

Energy Technology Data Exchange (ETDEWEB)

Blanco-Cano, X. [Instituto de Geofisica, UNAM, CU, Coyoacan 04510 DF (Mexico); Kajdic, P. [IRAP-University of Toulouse, CNRS, Toulouse (France); Aguilar-Rodriguez, E. [Instituto de Geofisica, UNAM, Morelia (Mexico); Russell, C. T. [ESS and IGPP, University of California, Los Angeles, 603 Charles Young Drive, Los Angeles, CA 90095 (United States); Jian, L. K. [NASA Goddard Space Flight Center, Greenbelt, MD and University of Maryland, College Park, MD (United States); Luhmann, J. G. [SSL, University of California Berkeley (United States)

2013-06-13

We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and {theta}{sub Bn}{approx}20-86 Degree-Sign . We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr {<=}0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at {approx}1 AU and have been producing suprathermal particles for a shorter time.

STEREO interplanetary shocks and foreshocks

International Nuclear Information System (INIS)

Blanco-Cano, X.; Kajdič, P.; Aguilar-Rodríguez, E.; Russell, C. T.; Jian, L. K.; Luhmann, J. G.

2013-01-01

We use STEREO data to study shocks driven by stream interactions and the waves associated with them. During the years of the extended solar minimum 2007-2010, stream interaction shocks have Mach numbers between 1.1-3.8 and θ Bn ∼20-86°. We find a variety of waves, including whistlers and low frequency fluctuations. Upstream whistler waves may be generated at the shock and upstream ultra low frequency (ULF) waves can be driven locally by ion instabilities. The downstream wave spectra can be formed by both, locally generated perturbations, and shock transmitted waves. We find that many quasiperpendicular shocks can be accompanied by ULF wave and ion foreshocks, which is in contrast to Earth's bow shock. Fluctuations downstream of quasi-parallel shocks tend to have larger amplitudes than waves downstream of quasi-perpendicular shocks. Proton foreshocks of shocks driven by stream interactions have extensions dr ≤0.05 AU. This is smaller than foreshock extensions for ICME driven shocks. The difference in foreshock extensions is related to the fact that ICME driven shocks are formed closer to the Sun and therefore begin to accelerate particles very early in their existence, while stream interaction shocks form at ∼1 AU and have been producing suprathermal particles for a shorter time.

Collisionless shock waves

International Nuclear Information System (INIS)

Sagdeev, R.Z.; Kennel, C.F.

1991-01-01

Collisionless shocks cannot occur naturally on the earth, because nearly all matter here consists of electrically neutral atoms and molecules. In space, however, high temperatures and ultraviolet radiation from hot stars decompose atoms into their constituent nuclei and electrons, producing a soup of electrically charged particles known as a plasma. Plasma physicists proposed that the collective electrical and magnetic properties of plasmas could produce interactions that take the place of collisions and permit shocks to form. In 1964 the theoretical work found its first experimental confirmation. Norman F. Ness and his colleagues at the Goddard Space Flight Center, using data collected from the iMP-1 spacecraft, detected clear signs that a collisionless shock exists where the solar wind encounters the earth's magnetic field. More recent research has demonstrated that collisionless shocks appear in a dazzling array of astronomical settings. For example, shocks have been found in the solar wind upstream (sunward) of all the planet and comets that have been visited by spacecraft. Violent flares on the sun generate shocks that propagate to the far reaches of the solar system; tremendous galactic outbursts create disruptions in the intergalactic medium that are trillions of times larger. In addition, many astrophysicists think that shocks from supernova explosions in our galaxy accelerate cosmic rays, a class of extraordinarily energetic elementary particles and atomic nuclei that rain down on the earth from all directions

Experimental Insights into the Mechanisms of Particle Acceleration by Shock Waves

Science.gov (United States)

Scolamacchia, T.; Scheu, B.; Dingwell, D. B.

2011-12-01

The generation of shock waves is common during explosive volcanic eruptions. Particles acceleration following shock wave propagation has been experimentally observed suggesting the potential hazard related to this phenomenon. Experiments and numerical models focused on the dynamics of formation and propagation of different types of shock waves when overpressurized eruptive mixtures are suddenly released in the atmosphere, using a pseudo-gas approximation to model those mixtures. Nevertheless, the results of several studies indicated that the mechanism of coupling between a gas and solid particles is valid for a limited grain-size range, which at present is not well defined. We are investigating particle acceleration mechanisms using a vertical shock tube consisting of a high-pressure steel autoclave (450 mm long, 28 mm in diameter), pressurized with argon, and a low-pressure 140 mm long acrylic glass autoclave, with the same internal diameter of the HP reservoir. Shock waves are generated by Ar decompression at atmospheric pressures at Pres/Pamb 100:1 to 150:1, through the failure of a diaphragm. Experiments were performed either with empty autoclave or suspending solid analogue particles 150 μm in size inside the LP autoclave. Incident Mach number varied from 1.7 to 2.1. Absolute and relative pressure sensors monitored P histories during the entire process, and a high-speed camera recorded particles movement at 20,000 to 30,000 fps. Preliminary results indicate pressure multiplication at the contact between shock waves and the particles in a time lapse of 100s μs, suggesting a possible different mechanism with respect to gas-particle coupling for particle acceleration.

Experimental and theoretical investigations of shock-induced flow of reactive porous media

Energy Technology Data Exchange (ETDEWEB)

Baer, M.R.; Graham, R.A.; Anderson, M.U. [Sandia National Labs., Albuquerque, NM (United States); Sheffield, S.A.; Gustavsen, R.L. [Los Alamos National Lab., NM (United States)

1996-11-01

In this work, the microscale processes of consolidation, deformation and reaction features of shocked porous materials are studied. Time- resolve particle velocities and stress fields associated with dispersive compaction waves are measured in gas-gun experiments. In these tests, a thin porous layer of HMX is shock-loaded at varied levels. At high impact, significant reaction is triggered by the rapid material distortion during compaction. In parallel modeling studies, continuum mixture theory is applied to describe the behavior of averaged wave-fields in heterogeneous media. One-dimensional simulations of gas-gun experiments demonstrate that the wave features and interactions with viscoelastic materials in the gauge package are well described by mixture theory, including reflected wave behavior and conditions where significant reaction is initiated. Numerical simulations of impact on a collection of discrete HMX `crystals` are also presented using shock physics analysis. Three-dimensional simulations indicate that rapid distortion occurs at material contact points; the nature of the dispersive fields includes large amplitude fluctuations of stress with wavelengths of several particle diameters. Localization of energy causes `hot-spots` due to shock focusing and plastic work as material flows into interstitial regions. These numerical experiments demonstrate that `hot-spots` are strongly influenced by multiple crystal interactions. This mesoscale study provides new insights into micromechanical behavior of heterogeneous energetic materials.

Response of beryllium to severe thermal shocks -simulation of disruption and vertical displacement events in future thermonuclear devices

Energy Technology Data Exchange (ETDEWEB)

Linke, J.; Duwe, R.; Roedig, M.; Schuster, A. [Association Euratom-Forschungszentrum Juelich GmbH (Germany); Merola, M.; Qian, R.H.

1998-01-01

Beryllium will play an important role for plasma facing components in next step thermonuclear fusion devices such as ITER. In particular for the first wall beryllium will be used with an armor thickness of several millimeters. However, during plasma instabilities they will experience severe thermal shocks. Here plasma disruptions with deposited energy densities of several ten MJm{sup -2} are the most essential damaging mechanism. However, a signifant fraction of the incident energy will be absorbed by a dense cloud of ablation vapor, hence reducing the effective energy density at the beryllium surface to values in the order of 10 MJm{sup -2}. To investigate the material response to all these plasma instabilities thermal shock tests on small scale test coupons (disruption effects) and on actively cooled divertor modules (VDEs) have been performed in the electron beam test facility JUDITH at ITER relevant surface heat loads. These tests have been performed on different bulk beryllium grades and on plasma sprayed coatings; the influence of pulse duration, power density, and temperature effects has been investigated experimentally. Detailed in-situ diagnostics (for beam characterization, optical pyrometry etc.) and post mortem analyses (profilometry, metallography, optical and electron microscopy) have been applied to quantify the resulting material damage. 1D- and 2D models have developed to verify the experimental results obtained in the electron beam simulation experiments. (J.P.N.)

Simple, economical heat-shock devices for zebrafish housing racks.

Science.gov (United States)

Duszynski, Robert J; Topczewski, Jacek; LeClair, Elizabeth E

2011-12-01

One reason for the popularity of the zebrafish (Danio rerio) as a model vertebrate is the ability to manipulate gene expression in this organism. A common method is to induce gene expression transiently under control of a heat-shock promoter (e.g., hsp70l). By making simple mechanical adjustments to small aquarium heaters (25-50W), we were able to produce consistent and reliable heat-shock conditions within a conventional zebrafish housing system. Up to two heat-shock intervals per day (>37°C) could be maintained under conditions of continuous flow (5-25 mL/min). Temperature logging every 30 s indicated rapid warm up times, consistent heat-shock lengths, and accurate and precise peak water temperatures (mean±SD=38°C±0.2°C). The biological effects of these heat-shock treatments were confirmed by observing inducible expression of enhanced green fluorescent protein (EGFP) and inhibition of caudal fin regeneration in a transgenic fish line expressing a dominant negative fibroblast growth factor receptor (Tg(hsp70l:dnfgfr1-EGFP)(pd1)). These devices are inexpensive, easily modified, and can be calibrated to accommodate a variety of experimental designs. After setup on a programmable timer, the heaters require no intervention to produce consistent daily heat shocks, and all other standard care protocols can be followed in the fish facility. The simplicity and stability of these devices make them suitable for long-term heat shocks at any stage of the zebrafish lifecycle (>7 days postfertilization), and useful for both laboratory and classroom experiments on transgenic zebrafish.

Nonlinear reflection of shock shear waves in soft elastic media.

Science.gov (United States)

Pinton, Gianmarco; Coulouvrat, François; Gennisson, Jean-Luc; Tanter, Mickaël

2010-02-01

For fluids, the theoretical investigation of shock wave reflection has a good agreement with experiments when the incident shock Mach number is large. But when it is small, theory predicts that Mach reflections are physically unrealistic, which contradicts experimental evidence. This von Neumann paradox is investigated for shear shock waves in soft elastic solids with theory and simulations. The nonlinear elastic wave equation is approximated by a paraxial wave equation with a cubic nonlinear term. This equation is solved numerically with finite differences and the Godunov scheme. Three reflection regimes are observed. Theory is developed for shock propagation by applying the Rankine-Hugoniot relations and entropic constraints. A characteristic parameter relating diffraction and non-linearity is introduced and its theoretical values are shown to match numerical observations. The numerical solution is then applied to von Neumann reflection, where curved reflected and Mach shocks are observed. Finally, the case of weak von Neumann reflection, where there is no reflected shock, is examined. The smooth but non-monotonic transition between these three reflection regimes, from linear Snell-Descartes to perfect grazing case, provides a solution to the acoustical von Neumann paradox for the shear wave equation. This transition is similar to the quadratic non-linearity in fluids.

Research on shock wave characteristics in the isolator of central strut rocket-based combined cycle engine under Ma5.5

Science.gov (United States)

Wei, Xianggeng; Xue, Rui; Qin, Fei; Hu, Chunbo; He, Guoqiang

2017-11-01

A numerical calculation of shock wave characteristics in the isolator of central strut rocket-based combined cycle (RBCC) engine fueled by kerosene was carried out in this paper. A 3D numerical model was established by the DES method. The kerosene chemical kinetic model used the 9-component and 12-step simplified mechanism model. Effects of fuel equivalence ratio, inflow total temperature and central strut rocket on-off on shock wave characteristics were studied under Ma5.5. Results demonstrated that with the increase of equivalence ratio, the leading shock wave moves toward upstream, accompanied with higher possibility of the inlet unstart. However, the leading shock wave moves toward downstream as the inflow total temperature rises. After the central strut rocket is closed, the leading shock wave moves toward downstream, which can reduce risks of the inlet unstart. State of the shear layer formed by the strut rocket jet flow and inflow can influence the shock train structure significantly.

Multiscale modeling of beryllium: quantum mechanics and laser-driven shock experiments using novel diagnostics

International Nuclear Information System (INIS)

Swift, D.C.; Paisley, Dennis L.; Kyrala, George A.; Hauer, Allan

2002-01-01

Ab initio quantum mechanics was used to construct a thermodynamically complete and rigorous equation of state for beryllium in the hexagonal and body-centred cubic structures, and to predict elastic constants as a function of compression. The equation of state agreed well with Hugoniot data and previously-published equations of state, but the temperatures were significantly different. The hexagonal/bcc phase boundary agreed reasonably well with published data, suggesting that the temperatures in our new equation of state were accurate. Shock waves were induced in single crystals and polycrystalline foils of beryllium, by direct illumination using the TRIDENT laser at Los Alamos. The velocity history at the surface of the sample was measured using a line-imaging VISAR, and transient X-ray diffraction (TXD) records were obtained with a plasma backlighter and X-ray streak cameras. The VISAR records exhibited elastic precursors, plastic waves, phase changes and spall. Dual TXD records were taken, in Bragg and Laue orientations. The Bragg lines moved in response to compression in the uniaxial direction. Because direct laser drive was used, the results had to be interpreted with the aid of radiation hydrodynamics simulations to predict the loading history for each laser pulse. In the experiments where there was evidence of polymorphism in the VISAR record, additional lines appeared in the Bragg and Laue records. The corresponding pressures were consistent with the phase boundary predicted by the quantum mechanical equation of state for beryllium. A model of the response of a single crystal of beryllium to shock loading is being developed using these new theoretical and experimental results. This model will be used in meso-scale studies of the response of the microstructure, allowing us to develop a more accurate representation of the behaviour of polycrystalline beryllium.

Relativistic Shock Acceleration

International Nuclear Information System (INIS)

Duffy, P.; Downes, T.P.; Gallant, Y.A.; Kirk, J.G.

1999-01-01

In this paper we briefly review the basic theory of shock waves in relativistic hydrodynamics and magneto-hydrodynamics, emphasising some astrophysically interesting cases. We then present an overview of the theory of particle acceleration at such shocks describing the methods used to calculate the spectral indices of energetic particles. Recent results on acceleration at ultra-relativistic shocks are discussed. (author)

Shock-induced electrical activity in polymeric solids. A mechanically induced bond scission model

International Nuclear Information System (INIS)

Graham, R.A.

1979-01-01

When polymeric solids are subjected to high-pressure shock loading, two anomalous electrical phenomena, shock-induced conduction and shock-induced polarization, are observed. The present paper proposes a model of mechanically induced bond scission within the shock front to account for the effects. An experimental study of shock-induced polarization in poly(pyromellitimide) (Vespel SP-1) is reported for shock compressions from 17 to 23% (pressures from 2.5 to 5.4 GPa). Poly(pyromellitimide) is found to be a strong generator of such polarization and the polarization is found to reflect an irreversible or highly hysteretic process. The present measurements are combined with prior measurements to establish a correlation between monomer structure and strength of shock-induced polarization; feeble signals are observed in the simpler monomer repeat units of poly(tetrafluoroethylene) and polyethylene while the strongest signals are observed in more complex monomers of poly(methyl methacrylate) and poly(pyromellitimide). It is also noted that there is an apparent correlation between shock-induced conduction and shock-induced polarization. Such shock-induced electrical activity is also found to be well correlated with the propensity for mechanical bond scission observed in experiments carried out in conventional mechanochemical studies. The bond scission model can account for characteristics observed for electrical activity in shock-loaded polymers and their correlation to monomer structure. Localization of elastic energy within the monomer repeat unit or along the main chain leads to the different propensities for bond scission and resulting shock-induced electrical activity

Nonequilibrium radiation behind a strong shock wave in CO{sub 2}-N{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Rond, C. [Universite de Provence - IUSTI, 5 rue Enrico Fermi, Marseille 13013 (France)], E-mail: rond@coria.fr; Boubert, P.; Felio, J.-M.; Chikhaoui, A. [Universite de Provence - IUSTI, 5 rue Enrico Fermi, Marseille 13013 (France)

2007-11-09

This work presents experiments reproducing plasma re-entry for one trajectory point of a Martian mission. The typical facility to investigate such hypersonic flow is shock tube; here we used the free-piston shock tube TCM2. Measurements of radiative flux behind the shock wave are realized thanks to time-resolved emission spectroscopy which is calibrated in intensity. As CN violet system is the main radiator in near UV-visible range, we have focused our study on its spectrum. Moreover a physical model, based on a multi-temperature kinetic code and a radiative code, for calculation of non equilibrium radiation behind a shock wave is developed for CO{sub 2}-N{sub 2}-Ar mixtures. Comparisons between experiments and calculations show that standard kinetic models (Park, McKenzie) are inefficient to reproduce our experimental results. Therefore we propose new rate coefficients in particular for the dissociation of CO{sub 2}, showing the way towards a better description of the chemistry of the mixture.

On possible structures of normal ionizing shock waves in electromagnetic shock tubes

International Nuclear Information System (INIS)

Liberman, M.A.; Synakh, V.S.; Zakajdakhov, V.V.; Velikovich, A.L.

1982-01-01

The problem of possible structures of normal ionizing shock waves is studied. On the basis of the general theory of ionizing shock waves in magnetic fields, a similarity solution of the piston problem for an impenetrable piston and a magnetic piston is described and a numerical solution of the non-stationary piston problem is obtained. It is shown that precursor photo-ionization of the neutral gas by the radiation of the shock-heated gas is the dominant factor in shaping normal ionizing shock structures. In particular, it is shown that the strong overheating of atoms and ions in shock fronts is due to the tensor form of Ohm's law in the precursor region. (author)

Multiple spacecraft observations of interplanetary shocks: four spacecraft determination of shock normals

International Nuclear Information System (INIS)

Russell, C.T.; Mellott, M.M.; Smith, E.J.; King, J.H.

1983-01-01

ISEE 1,2,3 IMP8, and Prognoz 7 observations of interplanetary shocks in 1978 and 1979 provide five instances where a single shock is observed by four spacecraft. These observations are used to determine best-fit normals for these five shocks. In addition to providing well-documented shocks for furture techniques. When the angle between upstream and downstream magnetic field is greater than 20, magnetic coplanarity can be an accurate single spacecraft method. However, no technique based solely on the magnetic measurements at one or multiple sites was universally accurate. Thus, we recommend using overdetermined shock normal solutions whenever possible, utilizing plasma measurements, separation vectors, and time delays together with magnetic constraints

Shock absorber

International Nuclear Information System (INIS)

Nemeth, J.D.

1981-01-01

A shock absorber for the support of piping and components in a nuclear power plant is described. It combines a high degree of stiffness under sudden shocks, e.g. seismic disturbances, with the ability to allow for thermal expansion without resistance when so required. (JIW)

DSMC simulations of shock interactions about sharp double cones

Science.gov (United States)

Moss, James N.

2001-08-01

This paper presents the results of a numerical study of shock interactions resulting from Mach 10 flow about sharp double cones. Computations are made by using the direct simulation Monte Carlo (DSMC) method of Bird. The sensitivity and characteristics of the interactions are examined by varying flow conditions, model size, and configuration. The range of conditions investigated includes those for which experiments have been or will be performed in the ONERA R5Ch low-density wind tunnel and the Calspan-University of Buffalo Research Center (CUBRC) Large Energy National Shock (LENS) tunnel.

Progress in the shock-ignition inertial confinement fusion concept

International Nuclear Information System (INIS)

Theobald, W.; Casner, A.; Nora, R.; Ribeyre, X.; Lafon, M.; Anderson, K. S.; Betti, R.; Craxton, R. S.; Delettrez, J. A.; Frenje, J. A.; Glebov, V. Yu; Gotchev, O. V.; Hohenberger, M.; Hu, S. X.; Marshall, F. J.; McCrory, R. L.; Meyerhofer, D. D.; Perkins, L. J.; Sangster, T. C.; Schurtz, G.; Seka, W.; Smalyuk, V. A.; Stoeckl, C.; Yaakobi, B.

2013-01-01

Shock-ignition experiments with peak laser intensities of ∼8 x 10 15 W/cm 2 were performed. D 2 -filled plastic shells were compressed on a low adiabat by 40 of the 60 OMEGA beams. The remaining 20 beams were delayed and tightly focused onto the imploding shell to generate a strong shock. Up to 35% backscattering of laser energy was measured at the highest intensity. Hard x-ray measurements reveal a relatively low hot-electron temperature of ∼40 keV, independent of intensity and spike onset time. (authors)