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Sample records for compressive shock wave

  1. Rarefaction shock waves in shock-compressed diamond <110> crystal

    NASA Astrophysics Data System (ADS)

    Perriot, Romain; Lin, You; Zhakhovsky, Vasily; White, Carter; Oleynik, Ivan

    2013-03-01

    Piston-driven shock compression of diamond <110> crystal was simulated by molecular dynamics using the REBO potential. At piston velocities between 2 and 5 km/s and corresponding pressures 117 GPA < P < 278 GPa, diamond sample undergoes a polymorphic phase transition, characterized by the coexistence of two elastically compressed phases, low-pressure phase A and high-pressure phase B. This phase transition results in the splitting of the shock wave into two elastic shock waves, composed of pure phase A and a mixture of phases A and B. Upon removal of the piston, a release wave is observed at the rear of the sample, turning into a rarefaction shock wave where the material undergoes the reverse phase transition from coexisting phases to the original low-pressure phase. For strong plastic waves induced by larger piston velocities the release wave propagates as a rarefaction wave without any phase transition corresponding to the adiabatic expansion along the plastic branch of the Hugoniot.

  2. Shock-wave studies of anomalous compressibility of glassy carbon

    NASA Astrophysics Data System (ADS)

    Molodets, A. M.; Golyshev, A. A.; Savinykh, A. S.; Kim, V. V.

    2016-02-01

    The physico-mechanical properties of amorphous glassy carbon are investigated under shock compression up to 10 GPa. Experiments are carried out on the continuous recording of the mass velocity of compression pulses propagating in glassy carbon samples with initial densities of 1.502(5) g/cm3 and 1.55(2) g/cm3. It is shown that, in both cases, a compression wave in glassy carbon contains a leading precursor with amplitude of 0.135(5) GPa. It is established that, in the range of pressures up to 2 GPa, a shock discontinuity in glassy carbon is transformed into a broadened compression wave, and shock waves are formed in the release wave, which generally means the anomalous compressibility of the material in both the compression and release waves. It is shown that, at pressure higher than 3 GPa, anomalous behavior turns into normal behavior, accompanied by the formation of a shock compression wave. In the investigated area of pressure, possible structural changes in glassy carbon under shock compression have a reversible character. A physico-mechanical model of glassy carbon is proposed that involves the equation of state and a constitutive relation for Poisson's ratio and allows the numerical simulation of physico-mechanical and thermophysical properties of glassy carbon of different densities in the region of its anomalous compressibility.

  3. PVDF Shock Compression Sensors in Shock Wave Physics

    NASA Astrophysics Data System (ADS)

    Bauer, F.

    2004-07-01

    Early works have shown that highly reproducible piezoelectric film PVDF (Poly(vinylidene fluoride)) can be reliably used in a wide range of precise stress and stress-rate measurements. The direct stress-derivative or stress-rate PVDF signals have nanosecond resolution and higher operating stress limits than any other technique. PVDF stress gauges have been used in many fields of shock wave physics. The present paper summarizes some of original applications of the PVDF gauges. Blast and shock in air measurements will be presented. Pressure responses of inert materials and polymer-materials will be recalled. Furthermore, example of pressure and particle velocity histories using PVDF and laser interferometry (VISAR) will be presented. Simultaneous measurements using VISAR and PVDF gauge will be discussed. The question of the validity of shock pressure profiles obtained with "in situ" PVDF gauges in one High Explosive in a detonation regime will be discussed.

  4. Shock-Wave Compression and Joule-Thomson Expansion

    NASA Astrophysics Data System (ADS)

    Hoover, Wm. G.; Hoover, Carol G.; Travis, Karl P.

    2014-04-01

    Structurally stable atomistic one-dimensional shock waves have long been simulated by injecting fresh cool particles and extracting old hot particles at opposite ends of a simulation box. The resulting shock profiles demonstrate tensor temperature, Txx≠Tyy and Maxwell's delayed response, with stress lagging strain rate and heat flux lagging temperature gradient. Here this same geometry, supplemented by a short-ranged external "plug" field, is used to simulate steady Joule-Kelvin throttling flow of hot dense fluid through a porous plug, producing a dilute and cooler product fluid.

  5. Chemical preparation and shock wave compression of carbon nitride precursors

    SciTech Connect

    Wixon, M.R. )

    1990-07-01

    Two synthetic routes have been developed to produce high-molecular-weight organic precursors containing a high weight fraction of nitrogen. One of the precursors is a pyrolysis residue of melamine-formaldehyde resin. The second precursor is the byproduct of an unusual low-temperature combustion reaction of tetrazole and its sodium salt. These precursors have been shock compressed under typical conditions for diamond and wurtzite boron nitride synthesis in an attempt to recover a new ultrahard carbon nitride. The recovered material has been analyzed by X-ray diffraction, FTIR, and Raman microprobe analysis. Diamond is present in the recovered material. This diamond is well ordered relative to diamond shock synthesized from carbonaceous starting materials.

  6. Shock formation and the ideal shape of ramp compression waves

    SciTech Connect

    Swift, D C; Kraus, R G; Loomis, E; Hicks, D G; McNaney, J M; Johnson, R P

    2008-05-29

    We derive expressions for shock formation based on the local curvature of the flow characteristics during dynamic compression. Given a specific ramp adiabat, calculated for instance from the equation of state for a substance, the ideal nonlinear shape for an applied ramp loading history can be determined. We discuss the region affected by lateral release, which can be presented in compact form for the ideal loading history. Example calculations are given for representative metals and plastic ablators. Continuum dynamics (hydrocode) simulations were in good agreement with the algebraic forms. Example applications are presented for several classes of laser-loading experiment, identifying conditions where shocks are desired but not formed, and where long duration ramps are desired.

  7. Thermal transport in shock wave-compressed solids using pulsed laser heating.

    PubMed

    La Lone, B M; Capelle, G; Stevens, G D; Turley, W D; Veeser, L R

    2014-07-01

    A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ~25 GPa and ~1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

  8. Dynamic response of kovar to shock and ramp-wave compression.

    SciTech Connect

    Sanchez, Dolores M.; Hall, Clint Allen; Wise, Jack LeRoy; Jones, Scott Christopher; Asay, James Russell

    2007-08-01

    Complementary gas-gun and electro-magnetic pulse tests conducted in Sandia's Dynamic Integrated Compression Experimental (DICE) Facility have, respectively, probed the behavior of electronic-grade Kovar samples under controlled impact and intermediate-strain-rate ICE (Isentropic Compression Experiment) loading. In all tests, velocity interferometer (VISAR) diagnostics provided time-resolved measurements of sample response for conditions involving one-dimensional (i:e:, uniaxial strain) compression and release. Wave-profile data from the gas-gun impact experiments have been analyzed to assess the Hugoniot Elastic Limit (HEL), Hugoniot equation of state, spall strength, and high-pressure yield strength of shocked Kovar. The ICE wave-profile data have been interpreted to determine the locus of isentropic stress-strain states generated in Kovar for deformation rates substantially lower than those associated with a shock process. The impact and ICE results have been compared to examine the influence of loading rate on high-pressure strength.

  9. Time-resolved shock compression of porous rutile: Wave dispersion in porous solids

    SciTech Connect

    Anderson, M.U.; Graham, R.A.; Holman, G.T.

    1993-08-01

    Rutile (TiO{sub 2}) samples at 60% of solid density have been shock-loaded from 0.21 to 6.1 GPa with sample thickness of 4 mm and studied with the PVDF piezoelectric polymer stress-rate gauge. The technique uses a copper capsule to contain the sample which has PVDF gauge packages in direct contact with front and rear surfaces. A precise measure is made of the compressive stress wave velocity through the sample, as well as the input and propagated shock stress. Initial density is known from sample preparation, and the amount of shock-compression is calculated from the measurement of shock velocity and input stress. Shock states and re-shock states are measured. Observed data are consistent with previously published high pressure data. It is observed that rutile has a ``crush strength`` near 6 GPa. Propagated stress-pulse rise times vary from 234 to 916 nsec. Propagated stress-pulse rise times of shock-compressed HMX, 2Al + Fe{sub 2}O{sub 3}, 3Ni + Al, and 5Ti + 3Si are presented.

  10. Time-resolved shock compression of porous rutile: Wave dispersion in porous solids

    SciTech Connect

    Anderson, M.U.; Graham, R.A.; Holman, G.T. )

    1994-07-10

    Rutile (TiO[sub 2]) samples at 60% of solid density have been shock-loaded from 0.21 to 6.1 GPa with sample thickness of 4 mm and studied with the PVDF piezoelectric polymer stress-rate gauge. The technique uses a copper capsule to contain the sample which has PVDF gauge packages in direct contact with the front and rear surfaces. A precise measure is made of the compressive stress wave velocity through the sample, as well as the input and propagated shock stress. The initial density is known from the sample preparation process, and the amount of shock-compression is calculated from the measurement of shock velocity and input stress. Shock states and re-shock states are measured. The observed data are consistent with previously published high pressure data. It is observed that rutile has a crush strength'' near 6 GPa. Propagated stress-pulse rise times vary from 234 to 916 nsec. Propagated stress-pulse rise times of shock-compressed HMX, 2Al+Fe[sub 2]O[sub 3], 3Ni+Al, and 5Ti+3Si are presented. [copyright] 1994 American Institute of Physics

  11. Shock-wave compression of silica gel as a model material for comets

    NASA Astrophysics Data System (ADS)

    Arasuna, Akane; Okuno, Masayuki; Chen, Liliang; Mashimo, Tsutomu; Okudera, Hiroki; Mizukami, Tomoyuki; Arai, Shoji

    2016-07-01

    A shock-wave compression experiment using synthesized silica gel was investigated as a model for a comet impact event on the Earth's surface. The sample shocked at 20.7 GPa showed considerable structural changes, a release of water molecules, and the dehydration of silanol (Si-OH) that led to the formation of a new Si-O-Si network structure containing larger rings (e.g., six-membered ring of SiO4 tetrahedra). The high aftershock temperature at 20.7 GPa, which could be close to 800 °C, influenced the sample structure. However, some silanols, which were presumed to be the mutually hydrogen-bonded silanol group, remained at pressures >20.7 GPa. This type of silanol along with a small number of water molecules may remain even after shock compression at 30.9 GPa, although the intermediate structure of the sample recovered was similar to that of silica glass.

  12. Material strength and inelastic deformation of silicon carbide under shock wave compression

    SciTech Connect

    Feng, R.; Raiser, G.F.; Gupta, Y.M.

    1998-01-01

    In-material, lateral, manganin foil gauge measurements were obtained in dense polycrystalline silicon carbide (SiC) shocked to peak longitudinal stresses ranging from 10{endash}24 GPa. The lateral gauge data were analyzed to determine the lateral stresses in the shocked SiC and the results were checked for self-consistency through dynamic two-dimensional computations. Over the stress range examined, the shocked SiC has an extremely high strength: the maximum shear stress supported by the material in the shocked state increases from 4.5 GPa at the Hugoniot elastic limit (HEL) of the material (11.5 GPa) to 7.0 GPa at stresses approximately twice the HEL. The latter value is 3.7{percent} of the shear modulus of the material. The elastic{endash}inelastic transition in the shocked SiC is nearly indistinctive. At stresses beyond twice the HEL, the data suggest a gradual softening with increasing shock compression. The post-HEL material strength evolution resembles neither catastrophic failure due to massive cracking nor classical plasticity response. Stress confinement, inherent in plane shock wave compression, contributes significantly to the observed material response. The results obtained are interpreted qualitatively in terms of an inhomogeneous deformation mechanism involving both in-grain microplasticity and highly confined microfissures. {copyright} {ital 1998 American Institute of Physics.}

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  14. Evolution of shock compression waves in a SiC ceramic

    NASA Astrophysics Data System (ADS)

    Savinykh, Andrey; Kanel, Gennady; Razorenov, Sergey; Rumyantsev, Vladimir

    2013-06-01

    The objective of this study was to estimate possible contribution of stress relaxation into the response of hard ceramic materials to high-rate compression and tension. With this goal, the free surface velocity histories have been measured for plane SiC ceramic samples of 3.07 g/cm3 density subjected to impact by a flyer plate. The sample thickness was varied from 0.5 mm up to 8.3 mm. The peak shock stress was in a range of 17.9 - 21.9 GPa. The Hugoniot elastic limit (HEL) is in a range of 8.34 to 8.72 GPa for this material, the spall strength value is 0.5 to 0.62 GPa. Both the HEL and the spall strength are in reasonable agreement with literature data for SiC ceramics of corresponding density. Measurements have not revealed any decay of the elastic precursor wave. Moreover, it has been found the evolution of the compression wave is practically self-similar and is well described by the simple wave approach. It follows from these observations the stress relaxation does not provide significant contribution into the response of hard ceramic materials to shock-wave loading. The ramped transition from elastic to plastic wave is caused by strain hardening of the material and by successive involving of grains of various orientations into the inelastic deformation process.

  15. Shock compression of precompressed deuterium

    SciTech Connect

    Armstrong, M R; Crowhurst, J C; Zaug, J M; Bastea, S; Goncharov, A F; Militzer, B

    2011-07-31

    Here we report quasi-isentropic dynamic compression and thermodynamic characterization of solid, precompressed deuterium over an ultrafast time scale (< 100 ps) and a microscopic length scale (< 1 {micro}m). We further report a fast transition in shock wave compressed solid deuterium that is consistent with the ramp to shock transition, with a time scale of less than 10 ps. These results suggest that high-density dynamic compression of hydrogen may be possible on microscopic length scales.

  16. Evolutions of elastic-plastic shock compression waves in different materials

    NASA Astrophysics Data System (ADS)

    Kanel, G. I.; Zaretsky, E. B.; Razorenov, S. V.; Savinykh, A. S.; Garkushin, G. V.

    2015-06-01

    Measurements of decay of the elastic precursor wave are used to determine the initial plastic strain rate as a function of the stress. Last years we performed large series of such kind experiments with metals and alloys at various temperatures, ceramics and glasses. In course of these measurements we observed several unexpected effects which have not got exhaustive explanations yet. In the presentation, we'll discuss a departure from self-similar development of the wave process which is accompanied with apparent sub-sonic wave propagation, changes of shape of elastic precursor wave as a result of variations in the material structure and the temperature, unexpected peculiarities of reflection of elastic-plastic waves from free surface, effects of internal friction at shock compression of glasses and some other effects. It seems the experimental data contain more information about kinetics of the time-dependent phenomena than we are able to get from their analysis now. Financial support from the Russian Science Foundation via Grant No 14-12-01127 is gratefully acknowledged.

  17. Attosecond shock waves.

    PubMed

    Zhokhov, P A; Zheltikov, A M

    2013-05-01

    Shock-wave formation is a generic scenario of wave dynamics known in nonlinear acoustics, fluid dynamics, astrophysics, seismology, and detonation physics. Here, we show that, in nonlinear optics, remarkably short, attosecond shock transients can be generated through a strongly coupled spatial and temporal dynamics of ultrashort light pulses, suggesting a pulse self-compression scenario whereby multigigawatt attosecond optical waveforms can be synthesized. PMID:23683197

  18. Simulation of systems for shock wave/compression waves damping in technological plants

    NASA Astrophysics Data System (ADS)

    Sumskoi, S. I.; Sverchkov, A. M.; Lisanov, M. V.; Egorov, A. F.

    2016-09-01

    At work of pipeline systems, flow velocity decrease can take place in the pipeline as a result of the pumps stop, the valves shutdown. As a result, compression waves appear in the pipeline systems. These waves can propagate in the pipeline system, leading to its destruction. This phenomenon is called water hammer (water hammer flow). The most dangerous situations occur when the flow is stopped quickly. Such urgent flow cutoff often takes place in an emergency situation when liquid hydrocarbons are being loaded into sea tankers. To prevent environment pollution it is necessary to stop the hydrocarbon loading urgently. The flow in this case is cut off within few seconds. To prevent an increase in pressure in a pipeline system during water hammer flow, special protective systems (pressure relief systems) are installed. The approaches to systems of protection against water hammer (pressure relief systems) modeling are described in this paper. A model of certain pressure relief system is considered. It is shown that in case of an increase in the intensity of hydrocarbons loading at a sea tanker, presence of the pressure relief system allows to organize safe mode of loading.

  19. Diffraction of a shock wave by a compression corner; regular and single Mach reflection

    NASA Technical Reports Server (NTRS)

    Vijayashankar, V. S.; Kutler, P.; Anderson, D.

    1976-01-01

    The two dimensional, time dependent Euler equations which govern the flow field resulting from the injection of a planar shock with a compression corner are solved with initial conditions that result in either regular reflection or single Mach reflection of the incident planar shock. The Euler equations which are hyperbolic are transformed to include the self similarity of the problem. A normalization procedure is employed to align the reflected shock and the Mach stem as computational boundaries to implement the shock fitting procedure. A special floating fitting scheme is developed in conjunction with the method of characteristics to fit the slip surface. The reflected shock, the Mach stem, and the slip surface are all treated as harp discontinuities, thus, resulting in a more accurate description of the inviscid flow field. The resulting numerical solutions are compared with available experimental data and existing first-order, shock-capturing numerical solutions.

  20. Al 1s-2p Absorption Spectroscopy of Shock-Wave Heating and Compression in Laser-Driven Planar Foil

    SciTech Connect

    Sawada, H.; Regan, S.P.; Radha, P.B.; Epstein, R.; Li, D.; Goncharov, V.N.; Hu, S.X.; Meyerhofer, D.D.; Delettrez, J.A.; Jaanimagi, P.A.; Smalyuk, V.A.; Boehly, T.R.; Sangster, T.C.; Yaakobi, B.; Mancini, R.C.

    2009-05-19

    Time-resolved Al 1s-2p absorption spectroscopy is used to diagnose direct-drive, shock-wave heating and compression of planar targets having nearly Fermi-degenerate plasma conditions (Te ~ 10–40 eV, rho ~ 3–11 g/cm^3) on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. A planar plastic foil with a buried Al tracer layer was irradiated with peak intensities of 10^14–10^15 W/cm^2 and probed with the pseudocontinuum M-band emission from a point-source Sm backlighter in the range of 1.4–1.7 keV. The laser ablation process launches 10–70 Mbar shock waves into the CH/Al/CH target. The Al 1s-2p absorption spectra were analyzed using the atomic physic code PRISMSPECT to infer Te and rho in the Al layer, assuming uniform plasma conditions during shock-wave heating, and to determine when the heat front penetrated the Al layer. The drive foils were simulated with the one-dimensional hydrodynamics code LILAC using a flux-limited (f =0.06 and f =0.1) and nonlocal thermal-transport model [V. N. Goncharov et al., Phys. Plasmas 13, 012702 (2006)]. The predictions of simulated shock-wave heating and the timing of heat-front penetration are compared to the observations. The experimental results for a wide variety of laser-drive conditions and buried depths have shown that the LILAC predictions using f = 0.06 and the nonlocal model accurately model the shock-wave heating and timing of the heat-front penetration while the shock is transiting the target. The observed discrepancy between the measured and simulated shock-wave heating at late times of the drive can be explained by the reduced radiative heating due to lateral heat flow in the corona.

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

    PubMed Central

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

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

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

    PubMed

    Sundaramurthy, Aravind; Chandra, Namas

    2014-01-01

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

  3. Shock compression modeling of metallic single crystals: comparison of finite difference, steady wave, and analytical solutions

    DOE PAGES

    Lloyd, Jeffrey T.; Clayton, John D.; Austin, Ryan A.; McDowell, David L.

    2015-07-10

    Background: The shock response of metallic single crystals can be captured using a micro-mechanical description of the thermoelastic-viscoplastic material response; however, using a such a description within the context of traditional numerical methods may introduce a physical artifacts. Advantages and disadvantages of complex material descriptions, in particular the viscoplastic response, must be framed within approximations introduced by numerical methods. Methods: Three methods of modeling the shock response of metallic single crystals are summarized: finite difference simulations, steady wave simulations, and algebraic solutions of the Rankine-Hugoniot jump conditions. For the former two numerical techniques, a dislocation density based framework describes themore » rate- and temperature-dependent shear strength on each slip system. For the latter analytical technique, a simple (two-parameter) rate- and temperature-independent linear hardening description is necessarily invoked to enable simultaneous solution of the governing equations. For all models, the same nonlinear thermoelastic energy potential incorporating elastic constants of up to order 3 is applied. Results: Solutions are compared for plate impact of highly symmetric orientations (all three methods) and low symmetry orientations (numerical methods only) of aluminum single crystals shocked to 5 GPa (weak shock regime) and 25 GPa (overdriven regime). Conclusions: For weak shocks, results of the two numerical methods are very similar, regardless of crystallographic orientation. For strong shocks, artificial viscosity affects the finite difference solution, and effects of transverse waves for the lower symmetry orientations not captured by the steady wave method become important. The analytical solution, which can only be applied to highly symmetric orientations, provides reasonable accuracy with regards to prediction of most variables in the final shocked state but, by construction, does not provide

  4. Shock compression modeling of metallic single crystals: comparison of finite difference, steady wave, and analytical solutions

    SciTech Connect

    Lloyd, Jeffrey T.; Clayton, John D.; Austin, Ryan A.; McDowell, David L.

    2015-07-10

    Background: The shock response of metallic single crystals can be captured using a micro-mechanical description of the thermoelastic-viscoplastic material response; however, using a such a description within the context of traditional numerical methods may introduce a physical artifacts. Advantages and disadvantages of complex material descriptions, in particular the viscoplastic response, must be framed within approximations introduced by numerical methods. Methods: Three methods of modeling the shock response of metallic single crystals are summarized: finite difference simulations, steady wave simulations, and algebraic solutions of the Rankine-Hugoniot jump conditions. For the former two numerical techniques, a dislocation density based framework describes the rate- and temperature-dependent shear strength on each slip system. For the latter analytical technique, a simple (two-parameter) rate- and temperature-independent linear hardening description is necessarily invoked to enable simultaneous solution of the governing equations. For all models, the same nonlinear thermoelastic energy potential incorporating elastic constants of up to order 3 is applied. Results: Solutions are compared for plate impact of highly symmetric orientations (all three methods) and low symmetry orientations (numerical methods only) of aluminum single crystals shocked to 5 GPa (weak shock regime) and 25 GPa (overdriven regime). Conclusions: For weak shocks, results of the two numerical methods are very similar, regardless of crystallographic orientation. For strong shocks, artificial viscosity affects the finite difference solution, and effects of transverse waves for the lower symmetry orientations not captured by the steady wave method become important. The analytical solution, which can only be applied to highly symmetric orientations, provides reasonable accuracy with regards to prediction of most variables in the final shocked state but, by construction, does not provide insight

  5. Shock compression of liquid hydrazine

    SciTech Connect

    Garcia, B.O.; Chavez, D.J.

    1995-01-01

    Liquid hydrazine (N{sub 2}H{sub 4}) is a propellant used by the Air Force and NASA for aerospace propulsion and power systems. Because the propellant modules that contain the hydrazine can be subject to debris impacts during their use, the shock states that can occur in the hydrazine need to be characterized to safely predict its response. Several shock compression experiments have been conducted in an attempt to investigate the detonability of liquid hydrazine; however, the experiments results disagree. Therefore, in this study, we reproduced each experiment numerically to evaluate in detail the shock wave profiles generated in the liquid hydrazine. This paper presents the results of each numerical simulation and compares the results to those obtained in experiment. We also present the methodology of our approach, which includes chemical kinetic experiments, chemical equilibrium calculations, and characterization of the equation of state of liquid hydrazine.

  6. Al 1s-2p absorption spectroscopy of shock-wave heating and compression in laser-driven planar foil

    SciTech Connect

    Sawada, H.; Regan, S. P.; Radha, P. B.; Epstein, R.; Li, D.; Goncharov, V. N.; Hu, S. X.; Meyerhofer, D. D.; Delettrez, J. A.; Jaanimagi, P. A.; Smalyuk, V. A.; Boehly, T. R.; Sangster, T. C.; Yaakobi, B.; Mancini, R. C.

    2009-05-15

    Time-resolved Al 1s-2p absorption spectroscopy is used to diagnose direct-drive, shock-wave heating and compression of planar targets having nearly Fermi-degenerate plasma conditions (T{sub e}{approx}10-40 eV, {rho}{approx}3-11 g/cm{sup 3}) on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. A planar plastic foil with a buried Al tracer layer was irradiated with peak intensities of 10{sup 14}-10{sup 15} W/cm{sup 2} and probed with the pseudocontinuum M-band emission from a point-source Sm backlighter in the range of 1.4-1.7 keV. The laser ablation process launches 10-70 Mbar shock waves into the CH/Al/CH target. The Al 1s-2p absorption spectra were analyzed using the atomic physic code PRISMSPECT to infer T{sub e} and {rho} in the Al layer, assuming uniform plasma conditions during shock-wave heating, and to determine when the heat front penetrated the Al layer. The drive foils were simulated with the one-dimensional hydrodynamics code LILAC using a flux-limited (f=0.06 and f=0.1) and nonlocal thermal-transport model [V. N. Goncharov et al., Phys. Plasmas 13, 012702 (2006)]. The predictions of simulated shock-wave heating and the timing of heat-front penetration are compared to the observations. The experimental results for a wide variety of laser-drive conditions and buried depths have shown that the LILAC predictions using f=0.06 and the nonlocal model accurately model the shock-wave heating and timing of the heat-front penetration while the shock is transiting the target. The observed discrepancy between the measured and simulated shock-wave heating at late times of the drive can be explained by the reduced radiative heating due to lateral heat flow in the corona.

  7. Shock waves data for minerals

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.; Johnson, Mary L.

    1994-01-01

    Shock compression of the materials of planetary interiors yields data which upon comparison with density-pressure and density-sound velocity profiles constrain internal composition and temperature. Other important applications of shock wave data and related properties are found in the impact mechanics of terrestrial planets and solid satellites. Shock wave equation of state, shock-induced dynamic yielding and phase transitions, and shock temperature are discussed. In regions where a substantial phase change in the material does not occur, the relationship between the particle velocity, U(sub p), and the shock velocity, U(sub s), is given by U(sub s) = C(sub 0) + S U(sub p), where C(sub 0) is the shock velocity at infinitesimally small particle velocity, or the ambient pressure bulk sound velocity. Numerical values for the shock wave equation of state for minerals and related materials of the solar system are provided.

  8. Measurements of elastic and plastic waves in polycrystalline diamond under shock compression

    NASA Astrophysics Data System (ADS)

    MacDonald, Michael; Fletcher, Luke; Vorberger, Jan; Gauthier, Maxence; Gamboa, Eliseo; Ravasio, Alessandra; Lee, Hae Ja; Galtier, Eric; Chen, Zhijiang; Kraus, Dominik; Barbrel, Ben; Drake, R. Paul; Glenzer, Siegfried

    2015-11-01

    Direct measurements of the crystal structure of materials under dynamic compression can be obtained using angularly resolved x-ray scattering at the MEC end station of the LCLS facility. In this experiment the 40 fs LCLS x-ray beam enabled time resolved measurements of elastic and plastic waves in polycrystalline diamond, the behavior of which are important to understand for the early stages of compression in inertial confinement fusion targets and planetary interiors. In this experiment two 527 nm optical lasers focused to 4 ×1014 W/cm2 were used to compress 20 and 40 μm polycrystalline diamond foils. Compression and lattice deformation measurements were made directly from angularly resolved x-ray scattering and compared to DFT simulations. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. 2013155705, DOE Office of Science, Fusion Energy Science under FWP 100182, by DOE/NNSA under grant number DE-NA0001840, and was performed at the MEC instrument of LCLS under contract No. SF00515. The target work was supported by a Laboratory Directed Research and Development grant.

  9. Shock compression of condensed nonideal plasmas

    NASA Astrophysics Data System (ADS)

    Fortov, Vladimir

    2001-06-01

    The physical properties of hot dense plasmas at megabar pressures are of great interest for astro- and planetary physics, inertial confinement fusion, energetics, technology and many other applications. The lecture presents the modern results of experimental investigations of equations of state, compositions, thermodynamical and transport properties, electrical conductivity and opacity of strongly coupled plasmas generated by intense shock and rarefaction waves. The experimental methods for generation of high energy densities in matter, drivers for shock waves and fast diagnostic methods are discussed. The application of intense shock waves to solid and porous targets allows us to degenerate Fermi-like plasmas with maximum pressure up to 4Gbar and temperatures 10^7 K. Compression of plasma by a series of incident and reflected shock waves allows us to decrease irreversible heating effects. As a result, such a multiple compression process becomes close to the isentropic one which permits us to reach much higher densities and lower temperatures compared to single shock compression. On the other hand, to increase the irreversibility effects and to generate high temperature plasma states the experiments on shock compression of porous samples (fine metal powder, aerogels) were performed. The shock compression of saturated metal vapors and previously compressed noble gases by incident and reflected shocks allows us to reach nonideal plasmas on the Hugoniot. The adiabatic expansion of matter initially compressed by intense shocks up to megabars gives us the chance to investigate the intermediate region between the solid and vapor phase of nonideal plasmas, including the metal-insulator transition phase and the high temperature saturation curve with critical points of metals.

  10. COMPRESSION WAVES AND PHASE PLOTS: SIMULATIONS

    SciTech Connect

    Orlikowski, D; Minich, R

    2011-08-01

    Compression wave analysis started nearly 50 years ago with Fowles. Coperthwaite and Williams gave a method that helps identify simple and steady waves. We have been developing a method that gives describes the non-isentropic character of compression waves, in general. One result of that work is a simple analysis tool. Our method helps clearly identify when a compression wave is a simple wave, a steady wave (shock), and when the compression wave is in transition. This affects the analysis of compression wave experiments and the resulting extraction of the high-pressure equation of state.

  11. Selfsimilar Spherical Compression Waves in Gas Dynamics

    NASA Astrophysics Data System (ADS)

    Meyer-ter-Vehn, J.; Schalk, C.

    1982-08-01

    A synopsis of different selfsimilar spherical compression waves is given pointing out their fundamental importance for the gas dynamics of inertial confinement fusion. Strong blast waves, various forms of isentropic compression waves, imploding shock waves and the solution for non-isentropic collapsing hollow spheres are included. A classification is given in terms of six singular points which characterise the different solutions and the relations between them. The presentation closely follows Guderley's original work on imploding shock waves

  12. Spall strength and ejecta production of gold under explosively driven shock wave compression

    SciTech Connect

    La Lone, B. M.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.; Holtkamp, D. B.

    2013-12-16

    Explosively driven shock wave experiments were conducted to characterize the spall strength and ejecta production of high-purity cast gold samples. The samples were from 0.75 to 1.84 mm thick and 30 mm in diameter. Peak stresses up to 44 GPa in gold were generated using PBX-9501 high explosive. Sample free surface and ejecta velocities were recorded using photonic Doppler velocimetry techniques. Lithium niobate pins were used to quantify the time dependence of the ejecta density and the total ejected mass. An optical framing camera for time-resolved imaging and a single-image x-ray radiograph were used for additional characterization. Free surface velocities exhibited a range of spall strengths from 1.7 to 2.4 GPa (mean: 2.0 ±0.3 GPa). The pullback signals were faint, minimal ringing was observed in the velocity records, and the spall layer continued to decelerate after first pull back. These results suggest finite tensile strength was present for some time after the initial void formation. Ejecta were observed for every sample with a roughened free surface, and the ejecta density increased with increased surface roughness, which was different in every experiment. The total ejected mass is consistent with the missing mass model.

  13. Shock wave compression of hexagonal-close-packed metal single crystals: Time-dependent, anisotropic elastic-plastic response of beryllium

    SciTech Connect

    Winey, J. M.; Gupta, Y. M.

    2014-07-21

    Understanding and modeling the response of hcp metals to high stress impulsive loading is challenging because the lower crystal symmetry, compared to cubic metals, results in a significantly more complex material response. To gain insight into the inelastic deformation of hcp metals subjected to high dynamic stresses, shock wave compression of single crystals provides a useful approach because different inelastic deformation mechanisms can be examined selectively by shock compression along different crystal orientations. As a representative example, we report, here, on wave propagation simulations for beryllium (Be) single crystals shocked along the c-axis, a-axis, and several low-symmetry directions to peak stresses reaching 7 GPa. The simulations utilized a time-dependent, anisotropic material model that incorporated dislocation dynamics, deformation twinning, and shear cracking based descriptions of inelastic deformation. The simulation results showed good overall agreement with measured wave profiles for all the different crystal orientations examined [Pope and Johnson, J. Appl. Phys. 46, 720 (1975)], including features arising from wave mode coupling due to the highly anisotropic inelastic response of Be. This good agreement demonstrates that the measured profiles can be understood in terms of dislocation slip along basal, prismatic, and pyramidal planes, together with deformation twinning along (101{sup ¯}2) planes. Our results show that the response of shocked Be single crystals involves the simultaneous operation of multiple, distinct inelastic deformation mechanisms for all orientations except the c-axis. For shocked c-axis Be, the measured wave profiles do not provide good discrimination between pyramidal slip and other inelastic deformation mechanisms, such as shear cracking. The findings presented here provide insight into the complex inelastic deformation response of shocked Be single crystals and are expected to be useful for other hcp crystals

  14. Shock wave compression of hexagonal-close-packed metal single crystals: Time-dependent, anisotropic elastic-plastic response of beryllium

    NASA Astrophysics Data System (ADS)

    Winey, J. M.; Gupta, Y. M.

    2014-07-01

    Understanding and modeling the response of hcp metals to high stress impulsive loading is challenging because the lower crystal symmetry, compared to cubic metals, results in a significantly more complex material response. To gain insight into the inelastic deformation of hcp metals subjected to high dynamic stresses, shock wave compression of single crystals provides a useful approach because different inelastic deformation mechanisms can be examined selectively by shock compression along different crystal orientations. As a representative example, we report, here, on wave propagation simulations for beryllium (Be) single crystals shocked along the c-axis, a-axis, and several low-symmetry directions to peak stresses reaching 7 GPa. The simulations utilized a time-dependent, anisotropic material model that incorporated dislocation dynamics, deformation twinning, and shear cracking based descriptions of inelastic deformation. The simulation results showed good overall agreement with measured wave profiles for all the different crystal orientations examined [Pope and Johnson, J. Appl. Phys. 46, 720 (1975)], including features arising from wave mode coupling due to the highly anisotropic inelastic response of Be. This good agreement demonstrates that the measured profiles can be understood in terms of dislocation slip along basal, prismatic, and pyramidal planes, together with deformation twinning along { 10 1 ¯ 2 } planes. Our results show that the response of shocked Be single crystals involves the simultaneous operation of multiple, distinct inelastic deformation mechanisms for all orientations except the c-axis. For shocked c-axis Be, the measured wave profiles do not provide good discrimination between pyramidal slip and other inelastic deformation mechanisms, such as shear cracking. The findings presented here provide insight into the complex inelastic deformation response of shocked Be single crystals and are expected to be useful for other hcp crystals. More

  15. Shock compression profiles in ceramics

    SciTech Connect

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  16. Design and Testing of CO2 Compression Using Supersonic Shock Wave Technology

    SciTech Connect

    Koopman, Aaron

    2015-06-01

    This report summarizes work performed by Ramgen and subcontractors in pursuit of the design and construction of a 10 MW supersonic CO2 compressor and supporting facility. The compressor will demonstrate application of Ramgen’s supersonic compression technology at an industrial scale using CO2 in a closed-loop. The report includes details of early feasibility studies, CFD validation and comparison to experimental data, static test experimental results, compressor and facility design and analyses, and development of aerodynamic tools. A summary of Ramgen's ISC Engine program activity is also included. This program will demonstrate the adaptation of Ramgen's supersonic compression and advanced vortex combustion technology to result in a highly efficient and cost effective alternative to traditional gas turbine engines. The build out of a 1.5 MW test facility to support the engine and associated subcomponent test program is summarized.

  17. Imploding conical shock waves

    NASA Astrophysics Data System (ADS)

    Paton, R. T.; Skews, B. W.; Rubidge, S.; Snow, J.

    2013-07-01

    The behaviour of conical shock waves imploding axisymmetrically was first studied numerically by Hornung (J Fluid Mech 409:1-12, 2000) and this prompted a limited experimental investigation into these complex flow patterns by Skews et al. (Shock Waves 11:323-326, 2002). Modification of the simulation boundary conditions, resulting in the loss of self-similarity, was necessary to image the flow experimentally. The current tests examine the temporal evolution of these flows utilising a converging conical gap of fixed width fed by a shock wave impinging at its entrance, supported by CFD simulations. The effects of gap thickness, angle and incident shock strength were investigated. The wave initially diffracts around the outer lip of the gap shedding a vortex which, for strong incident shock cases, can contain embedded shocks. The converging shock at exit reflects on the axis of symmetry with the reflected wave propagating outwards resulting in a triple point developing on the incident wave together with the associated shear layer. This axisymmetric shear layer rolls up into a mushroom-shaped toroidal vortex ring and forward-facing jet. For strong shocks, this deforms the Mach disk to the extent of forming a second triple point with the primary shock exhibiting a double bulge. Separate features resembling the Richtmeyer-Meshkov and Kelvin-Helmholtz instabilities were noted in some tests. Aside from the incident wave curvature, the reflection patterns demonstrated correspond well with the V- and DV-types identified by Hornung although type S was not clearly seen, possibly due to the occlusion of the reflection region by the outer diffraction vortex at these early times. Some additional computational work explicitly exploring the limits of the parameter space for such systems has demonstrated the existence of a possible further reflection type, called vN-type, which is similar to the von Neumann reflection for plane waves. It is recommended that the parameter space be

  18. FLOW FIELD IN SUPERSONIC MIXED-COMPRESSION INLETS AT ANGLE OF ATTACK USING THE THREE DIMENSIONAL METHOD OF CHARACTERISTICS WITH DISCRETE SHOCK WAVE FITTING

    NASA Technical Reports Server (NTRS)

    Bishop, A. R.

    1994-01-01

    This computer program calculates the flow field in the supersonic portion of a mixed-compression aircraft inlet at non-zero angle of attack. This approach is based on the method of characteristics for steady three-dimensional flow. The results of this program agree with those produced by the two-dimensional method of characteristics when axisymmetric flow fields are calculated. Except in regions of high viscous interaction and boundary layer removal, the results agree well with experimental data obtained for threedimensional flow fields. The flow field in a variety of axisymmetric mixed compression inlets can be calculated using this program. The bow shock wave and the internal shock wave system are calculated using a discrete shock wave fitting procedure. The internal flow field can be calculated either with or without the discrete fitting of the internal shock wave system. The influence of molecular transport can be included in the calculation of the external flow about the forebody and in the calculation of the internal flow when internal shock waves are not discretely fitted. The viscous and thermal diffussion effects are included by treating them as correction terms in the method of characteristics procedure. Dynamic viscosity is represented by Sutherland's law and thermal conductivity is represented as a quadratic function of temperature. The thermodynamic model used is that of a thermally and calorically perfect gas. The program assumes that the cowl lip is contained in a constant plane and that the centerbody contour and cowl contour are smooth and have continuous first partial derivatives. This program cannot calculate subsonic flow, the external flow field if the bow shock wave does not exist entirely around the forebody, or the internal flow field if the bow flow field is injected into the annulus. Input to the program consists of parameters to control execution, to define the geometry, and the vehicle orientation. Output consists of a list of parameters

  19. Uncertainty Assessments of 2D and Axisymmetric Hypersonic Shock Wave - Turbulent Boundary Layer Interaction Simulations at Compression Corners

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Berry, Scott A.; VanNorman, John W.

    2011-01-01

    This paper is one of a series of five papers in a special session organized by the NASA Fundamental Aeronautics Program that addresses uncertainty assessments for CFD simulations in hypersonic flow. Simulations of a shock emanating from a compression corner and interacting with a fully developed turbulent boundary layer are evaluated herein. Mission relevant conditions at Mach 7 and Mach 14 are defined for a pre-compression ramp of a scramjet powered vehicle. Three compression angles are defined, the smallest to avoid separation losses and the largest to force a separated flow engaging more complicated flow physics. The Baldwin-Lomax and the Cebeci-Smith algebraic models, the one-equation Spalart-Allmaras model with the Catrix-Aupoix compressibility modification and two-equation models including Menter SST, Wilcox k-omega 98, and Wilcox k-omega 06 turbulence models are evaluated. Each model is fully defined herein to preclude any ambiguity regarding model implementation. Comparisons are made to existing experimental data and Van Driest theory to provide preliminary assessment of model form uncertainty. A set of coarse grained uncertainty metrics are defined to capture essential differences among turbulence models. Except for the inability of algebraic models to converge for some separated flows there is no clearly superior model as judged by these metrics. A preliminary metric for the numerical component of uncertainty in shock-turbulent-boundary-layer interactions at compression corners sufficiently steep to cause separation is defined as 55%. This value is a median of differences with experimental data averaged for peak pressure and heating and for extent of separation captured in new, grid-converged solutions presented here. This value is consistent with existing results in a literature review of hypersonic shock-turbulent-boundary-layer interactions by Roy and Blottner and with more recent computations of MacLean.

  20. When shock waves collide

    DOE PAGES

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

    2016-06-01

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

  1. When Shock Waves Collide

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Li, Xiaojie; Hokamoto, Kazuyuki

    2014-12-01

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

  3. Shock compression dynamics under a microscope.

    NASA Astrophysics Data System (ADS)

    Dlott, Dana

    2015-06-01

    We have developed a tabletop laser flyer launch system1 that solves many of the problems that plagued previous efforts. Using a novel mechanism where a spatially-uniform laser pulse creates a shock in a glass substrate just underneath a metal foil, we can launch tiny (0.7 mm diameter x 100 μm thick) flyers at speeds ranging from 0-5 km/s and the foils are flat, cold and intact. This tabletop launch system, where we often launch 100 flyers per day, provides a platform for a wide variety of time-resolved spectroscopies. The shocked material is viewed by a microscope objective that transmits near-infrared light from a photon Doppler velocimeter to monitor the flyer, and collects the light for spectroscopic and video images. Fluorescent probes, which have been highly developed for the biomedical sciences, have proven especially useful for these experiments. Using emission measurements, we have investigated the fundamental mechanisms of many shock wave effects including: viscoelastic compression of high molecular weight polymers, visualization of shocks in porous media such as sand, where we can observe the behavior of individual grains of sand, shock attenuation by passing the shock through reactive materials that undergo endothermic chemical reactions, and shock initiation of nanoenergetic materials.

  4. Shock and Static Compression of Nitrobenzene

    NASA Astrophysics Data System (ADS)

    Kozu, Naoshi; Arai, Mitsuru; Tamura, Masamitsu; Fujihisa, Hiroshi; Aoki, Katsutoshi; Yoshida, Masatake

    2000-08-01

    The Hugoniot and static compression curve (isotherm) were investigated using explosive plane wave generators and diamond anvil cells, respectively. The obtained Hugoniot from the shock experiments is represented by two linear lines: Us=2.52+1.23 up (0.8shock velocity and the particle velocity in km/s, respectively. A kink exists at around 15 GPa. The line for the higher particle velocities agrees well with the Hugoniot of detonation products calculated by the CHEETAH code. This suggests that nitrobenzene detonates in this range. Under static high pressure over 7 GPa, nitrobenzene undergoes a reaction that is expected to be polymerization. Considering the Hugoniot and the isotherm, it is plausible that shocked nitrobenzene (<15 GPa) is in the liquid state.

  5. Shock wave treatment in medicine.

    PubMed

    Shrivastava, S K; Kailash

    2005-03-01

    Extracorporeal shock wave therapy in orthopedics and traumatology is still a young therapy method. Since the last few years the development of shock wave therapy has progressed rapidly. Shock waves have changed the treatment of urolithiasis substantially. Today shock waves are the first choice to treat kidney and urethral stones. Urology has long been the only medical field for shock waves in medicine. Meanwhile shock waves have been used in orthopedics and traumatology to treat insertion tendinitis, avascular necrosis of the head of femur and other necrotic bone alterations. Another field of shock wave application is the treatment of tendons, ligaments and bones on horses in veterinary medicine. In the present paper we discuss the basic theory and application of shock waves and its history in medicine. The idea behind using shock wave therapy for orthopedic diseases is the stimulation of healing in tendons, surrounding tissue and bones. PMID:15933416

  6. TIMING OF SHOCK WAVES

    DOEpatents

    Tuck, J.L.

    1955-03-01

    This patent relates to means for ascertaining the instant of arrival of a shock wave in an exploslve charge and apparatus utilizing this means to coordinate the timing of two operations involving a short lnterval of time. A pair of spaced electrodes are inserted along the line of an explosive train with a voltage applied there-across which is insufficient to cause discharge. When it is desired to initiate operation of a device at the time the explosive shock wave reaches a particular point on the explosive line, the device having an inherent time delay, the electrodes are located ahead of the point such that the ionization of the area between the electrodes caused by the traveling explosive shock wave sends a signal to initiate operation of the device to cause it to operate at the proper time. The operated device may be photographic equipment consisting of an x-ray illuminating tube.

  7. Reliable estimation of shock position in shock-capturing compressible hydrodynamics codes

    SciTech Connect

    Nelson, Eric M

    2008-01-01

    The displacement method for estimating shock position in a shock-capturing compressible hydrodynamics code is introduced. Common estimates use simulation data within the captured shock, but the displacement method uses data behind the shock, making the estimate consistent with and as reliable as estimates of material parameters obtained from averages or fits behind the shock. The displacement method is described in the context of a steady shock in a one-dimensional lagrangian hydrodynamics code, and demonstrated on a piston problem and a spherical blast wave.The displacement method's estimates of shock position are much better than common estimates in such applications.

  8. Exhaust Nozzle Plume and Shock Wave Interaction

    NASA Technical Reports Server (NTRS)

    Castner, Raymond S.; Elmiligui, Alaa; Cliff, Susan

    2013-01-01

    Fundamental research for sonic boom reduction is needed to quantify the interaction of shock waves generated from the aircraft wing or tail surfaces with the exhaust plume. Both the nozzle exhaust plume shape and the tail shock shape may be affected by an interaction that may alter the vehicle sonic boom signature. The plume and shock interaction was studied using Computational Fluid Dynamics simulation on two types of convergent-divergent nozzles and a simple wedge shock generator. The nozzle plume effects on the lower wedge compression region are evaluated for two- and three-dimensional nozzle plumes. Results show that the compression from the wedge deflects the nozzle plume and shocks form on the deflected lower plume boundary. The sonic boom pressure signature of the wedge is modified by the presence of the plume, and the computational predictions show significant (8 to 15 percent) changes in shock amplitude.

  9. Whistler Waves Associated with Weak Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Velez, J. C. Ramirez; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Russell, C. T.; Kajdic, P.; Jian,, L. K.; Luhmann, J. G.

    2012-01-01

    We analyze the properties of 98 weak interplanetary shocks measured by the dual STEREO spacecraft over approximately 3 years during the past solar minimum. We study the occurrence of whistler waves associated with these shocks, which on average are high beta shocks (0.2 < Beta < 10). We have compared the waves properties upstream and downstream of the shocks. In the upstream region the waves are mainly circularly polarized, and in most of the cases (approx. 75%) they propagate almost parallel to the ambient magnetic field (<30 deg.). In contrast, the propagation angle with respect to the shock normal varies in a broad range of values (20 deg. to 90 deg.), suggesting that they are not phase standing. We find that the whistler waves can extend up to 100,000 km in the upstream region but in most cases (88%) are contained in a distance within 30,000 km from the shock. This corresponds to a larger region with upstream whistlers associated with IP shocks than previously reported in the literature. The maximum amplitudes of the waves are observed next to the shock interface, and they decrease as the distance to the shock increases. In most cases the wave propagation direction becomes more aligned with the magnetic field as the distance to the shock increases. These two facts suggest that most of the waves in the upstream region are Landau damping as they move away from the shock. From the analysis we also conclude that it is likely that the generation mechanism of the upstream whistler waves is taking place at the shock interface. In the downstream region, the waves are irregularly polarized, and the fluctuations are very compressive; that is, the compressive component of the wave clearly dominates over the transverse one. The majority of waves in the downstream region (95%) propagate at oblique angles with respect to the ambient magnetic field (>60 deg.). The wave propagation with respect to the shock-normal direction has no preferred direction and varies similarly to

  10. Selfsimilar spherical compression waves in gas dynamics

    NASA Astrophysics Data System (ADS)

    Meyer-Ter-Vehn, J.; Schalk, C.

    1982-05-01

    A synopsis of different selfsimilar spherical compression waves is given pointing out their fundamental importance for the gas dynamics of inertial confinement fusion. Strong blast waves, various forms of isentropic collapsing hollow spheres are included. A classification is given in terms of six singular points which characterize the different solutions and the relations between them. The presentation closely follows Guderley's original work on imploding shock waves.

  11. Shock waves: The Maxwell-Cattaneo case.

    PubMed

    Uribe, F J

    2016-03-01

    Several continuum theories for shock waves give rise to a set of differential equations in which the analysis of the underlying vector field can be done using the tools of the theory of dynamical systems. We illustrate the importance of the divergences associated with the vector field by considering the ideas by Maxwell and Cattaneo and apply them to study shock waves in dilute gases. By comparing the predictions of the Maxwell-Cattaneo equations with shock wave experiments we are lead to the following conclusions: (a) For low compressions (low Mach numbers: M) the results from the Maxwell-Cattaneo equations provide profiles that are in fair agreement with the experiments, (b) as the Mach number is increased we find a range of Mach numbers (1.27 ≈ M(1) < M < M(2) ≈ 1.90) such that numerical shock wave solutions to the Maxwell-Cattaneo equations cannot be found, and

  12. Shock waves: The Maxwell-Cattaneo case.

    PubMed

    Uribe, F J

    2016-03-01

    Several continuum theories for shock waves give rise to a set of differential equations in which the analysis of the underlying vector field can be done using the tools of the theory of dynamical systems. We illustrate the importance of the divergences associated with the vector field by considering the ideas by Maxwell and Cattaneo and apply them to study shock waves in dilute gases. By comparing the predictions of the Maxwell-Cattaneo equations with shock wave experiments we are lead to the following conclusions: (a) For low compressions (low Mach numbers: M) the results from the Maxwell-Cattaneo equations provide profiles that are in fair agreement with the experiments, (b) as the Mach number is increased we find a range of Mach numbers (1.27 ≈ M(1) < M < M(2) ≈ 1.90) such that numerical shock wave solutions to the Maxwell-Cattaneo equations cannot be found, and PMID:27078450

  13. Critical point anomalies include expansion shock waves

    SciTech Connect

    Nannan, N. R.; Guardone, A.; Colonna, P.

    2014-02-15

    From first-principle fluid dynamics, complemented by a rigorous state equation accounting for critical anomalies, we discovered that expansion shock waves may occur in the vicinity of the liquid-vapor critical point in the two-phase region. Due to universality of near-critical thermodynamics, the result is valid for any common pure fluid in which molecular interactions are only short-range, namely, for so-called 3-dimensional Ising-like systems, and under the assumption of thermodynamic equilibrium. In addition to rarefaction shock waves, diverse non-classical effects are admissible, including composite compressive shock-fan-shock waves, due to the change of sign of the fundamental derivative of gasdynamics.

  14. The Structure of Weak Shock Waves in Water

    NASA Astrophysics Data System (ADS)

    Baty, Roy; Tucker, Don; Hagelberg, Carl

    2010-11-01

    This talk presents solutions of the Navier-Stokes equations that model weak shock waves in water. One-dimensional jump functions are computed to describe the viscous microstructure of hydrodynamic shocks, which are approximately isentropic. The Tate and Grueneisen equations of state are applied separately with the conservation laws to derive the flow microstructure for shock compressions and pressures up to 1.3 and 20.0 kbars, respectively. The Navier-Stokes equations are integrated along characteristic lines to compute the shock wave thickness. On characteristic lines, the shock wave jump functions reduce to integral equations. The Tate and Grueneisen equations of state yield similar, strictly monotonically increasing, shock wave microstructures. Moreover, the non-dimensional shock wave thicknesses predicted by these equations of state as a function of compression are very similar.

  15. Radiative Shock Waves In Emerging Shocks

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  16. Unstable Mixing of Compressible Fluids Driven by Cylindrical Shocks

    NASA Astrophysics Data System (ADS)

    Graham, Mary Jane; Zhang, Qiang

    1996-11-01

    As an incident shock wave hits a material interface between two compressible fluids of different densities, the interface becomes unstable. Small disturbances at the interface start to grow forming spikes and bubbles. This interfacial instability is known as the Richtmyer-Meshkov (RM) instability. To date, the majority of the numerical and theoretical studies are for the RM instability in plane geometry. We present a systematic study of the RM instabiliy in cylindrical geometry with curved shocks for all four classes: shock exploding from light fluid to heavy fluid; (2) shock imploding from light fluid to heavy fluid; (3) shock exploding from heavy fluid to light fluid; and (4) shock imploding from heavy fluid to light fluid. A careful study and understanding of the effects of various physical parameters will be presented: including the curvature of the geometry, the incident shock strength, the amplitude of the perturbation as well as the number of fingers at the material interface, and the phenomenon of reshock.

  17. Shock Propagation and Instability Structures in Compressed Silica Aerogels

    SciTech Connect

    Howard, W M; Molitoris, J D; DeHaven, M R; Gash, A E; Satcher, J H

    2002-05-30

    We have performed a series of experiments examining shock propagation in low density aerogels. High-pressure ({approx}100 kbar) shock waves are produced by detonating high explosives. Radiography is used to obtain a time sequence imaging of the shocks as they enter and traverse the aerogel. We compress the aerogel by impinging shocks waves on either one or both sides of an aerogel slab. The shock wave initially transmitted to the aerogel is very narrow and flat, but disperses and curves as it propagates. Optical images of the shock front reveal the initial formation of a hot dense region that cools and evolves into a well-defined microstructure. Structures observed in the shock front are examined in the framework of hydrodynamic instabilities generated as the shock traverses the low-density aerogel. The primary features of shock propagation are compared to simulations, which also include modeling the detonation of the high explosive, with a 2-D Arbitrary Lagrange Eulerian hydrodynamics code The code includes a detailed thermochemical equation of state and rate law kinetics. We will present an analysis of the data from the time resolved imaging diagnostics and form a consistent picture of the shock transmission, propagation and instability structure.

  18. Electrical conductivity and compressibility of sulfur under shock loading

    SciTech Connect

    Postnov, V.I.; Anan'eva, L.A.; Dremin, A.N.; Nabatov, S.S.; Yakushev, V.V.

    1987-01-01

    The authors mathematically and experimentally assess the transition of orthorhombic elementary sulfur from a dielectric to a superconducting regime under the influence of pressure generated by shock wave loading. They also determine its compressibility over a range of 4-38 GPa.

  19. Shock Waves in Dispersive Eulerian Fluids

    NASA Astrophysics Data System (ADS)

    Hoefer, Mark

    2013-11-01

    Shock waves in dispersive media with negligible dissipation are studied in the context of the compressible Euler equations with weak dispersion. Example fluids of this type include superfluids, shallow water flows, and ion-acoustic plasma. A characterization of one-dimensional dispersive shock waves (DSWs) will be presented. DSWs are sharply distinct from classical, dissipatively regularized shock waves both in terms of physical significance and mathematical description. Drawing on terminology from classical gas dynamics, jump conditions (shock loci and speeds) and admissibility criteria for the long time evolution of step-like initial data will be presented utilizing a nonlinear wave averaging technique. While entropy conditions determine admissible, dissipatively regularized shock waves, conservative, dispersive systems are time reversible and can exhibit positive or negative dispersion. The universal structure of weak shocks will be shown to depend solely upon the dispersion sign and pressure law. Large amplitude DSWs can exhibit novel effects such as cavitation and ``implosion'' yielding internal, multi-phase dynamics. Support from NSF DMS-1008973.

  20. Imaging Supersonic Aircraft Shock Waves

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M.; Stacy, Kathryn; Vieira, Gerald J.; Haering, Edward A., Jr.; Bowers, Albion H.

    1997-01-01

    A schlieren imaging system that uses the sun as a light source was developed it) obtain direct flow-field images of shock waves of aircraft in flight. This system was used to study how shock waves evolve to form sonic booms. The image quality obtained was limited by several optical and mechanical factors. Converting the photographs to digital images and applying digital image-processing techniques greatly improved the final quality of the images and more clearly showed the shock structures.

  1. PARTICLE ENERGY SPECTRA AT TRAVELING INTERPLANETARY SHOCK WAVES

    SciTech Connect

    Reames, Donald V.

    2012-09-20

    We have searched for evidence of significant shock acceleration of He ions of {approx}1-10 MeV amu{sup -1} in situ at 258 interplanetary traveling shock waves observed by the Wind spacecraft. We find that the probability of observing significant acceleration, and the particle intensity observed, depends strongly upon the shock speed and less strongly upon the shock compression ratio. For most of the 39 fast shocks with significant acceleration, the observed spectral index agrees with either that calculated from the shock compression ratio or with the spectral index of the upstream background, when the latter spectrum is harder, as expected from diffusive shock theory. In many events the spectra are observed to roll downward at higher energies, as expected from Ellison-Ramaty and from Lee shock-acceleration theories. The dearth of acceleration at {approx}85% of the shocks is explained by (1) a low shock speed, (2) a low shock compression ratio, and (3) a low value of the shock-normal angle with the magnetic field, which may cause the energy spectra that roll downward at energies below our observational threshold. Quasi-parallel shock waves are rarely able to produce measurable acceleration at 1 AU. The dependence of intensity on shock speed, seen here at local shocks, mirrors the dependence found previously for the peak intensities in large solar energetic-particle events upon speeds of the associated coronal mass ejections which drive the shocks.

  2. Shock compression and equation of state of C60 fullerite

    NASA Astrophysics Data System (ADS)

    Milyavskiy, Vladimir; Khishchenko, Konstantin; Utkin, Alexander; Yakushev, Vladislav; Zhuk, Andrey; Fortov, Vladimir

    2007-06-01

    Recently, we have experimentally studied shock compressibility of C60 fullerite and sound velocity in shock-compressed fullerite [1]. The Hugoniot of C60 fullerite had a set of peculiarities. Appearance of a rather hard carbon phase was detected at shock pressure ˜ 9 GPa. We assume that it is a 2D-polymerized C60 phase. With increase of shock pressure, destruction of this phase and formation of a graphite-like carbon occurs. With further increase of shock pressure, the graphite- like carbon transforms to a diamond-like phase. If shock pressure is higher than ˜ 33 GPa, shock compressibility of C60 fullerite is determined by the thermodynamic properties of the diamond-like phase. The results of the shock-wave measurements were used for the description of thermodynamic properties of C60 fullerite and products of its transformations in a wide range of pressures and temperatures. A semiempirical equation of state for the simple cubic phase of C60 fullerite is proposed. The EOS we have developed for fullerite C60 provides a consistent representation of the available experimental data. The work was supported by RFBR. [1] Milyavskiy V.V., Utkin A.V., Zhuk A.Z., Yakushev V.V. and Fortov V.E. Diamond and Rel. Mat. 14 (2005) 1920.

  3. Models and Observations of Shock Wave Propagation in Volcanic Settings

    NASA Astrophysics Data System (ADS)

    Anderson, J.; Johnson, J. B.; Ruiz, M. C.; Steele, A.

    2013-12-01

    High-amplitude air waves (shock waves) propagate nonlinearly; although this strongly affects recorded signals, it is not commonly modeled in studies of volcanic explosions. Failure to account for the shock wave component of air waves can lead to underestimation of source power and inaccurate source times. Additionally, propagation effects can significantly alter waveforms from the original source signals. In order to permit more accurate studies of shock wave sources, we examine modeling techniques and observations of shock waves. Shock wave signals begin with strong, abrupt compressions that, compared to typical sound waves, propagate and decay more quickly. Because of the high-amplitude discontinuities, numerical methods that are commonly used to study linear sound waves become unstable and inaccurate when applied to shock waves. We discuss the use of other techniques that are capable of modeling shock wave propagation. Equations relating wave speed to the difference of various physical quantities across the shock (such as pressure, density, and particle velocity) are useful for modeling these waves. Addressing the shock explicitly as such, in conjunction with use of traditional numerical methods for the remainder of the signal, permits modeling of full shock waveforms. Additionally, we present examples of recorded volcanic signals that propagate nonlinearly and demonstrate propagation effects on amplitude, waveform, and spectrum.

  4. Shock-wave properties of soda-lime glass

    SciTech Connect

    Grady, D.E.; Chhabildas, L.C.

    1996-11-01

    Planar impact experiments and wave profile measurements provided single and double shock equation of state data to 30 GPa. Both compression wave wave profile structure and release wave data were used to infer time-dependent strength and equation of state properties for soda-lime glass.

  5. Shock Wave Structure in Particulate Composites

    NASA Astrophysics Data System (ADS)

    Rauls, Michael; Ravichandran, Guruswami

    2015-06-01

    Shock wave experiments are conducted on a particulate composite consisting of a polymethyl methacrylate (PMMA) matrix reinforced by glass beads. Such a composite with an impedance mismatch of 4.3 closely mimics heterogeneous solids of interest such as concrete and energetic materials. The composite samples are prepared using a compression molding process. The structure and particle velocity rise times of the shocks are examined using forward ballistic experiments. Reverse ballistic experiments are used to track how the interface density influences velocity overshoot above the steady state particle velocity. The effects of particle size (0.1 to 1 mm) and volume fraction of glass beads (30-40%) on the structure of the leading shock wave are investigated. It is observed that the rise time increases with increasing particle size and scales linearly for the range of particle sizes considered here. Results from numerical simulations using CTH are compared with experimental results to gain insights into wave propagation in heterogeneous particulate composites.

  6. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, Stephan; Ford, Jessica; Martinez, David; Plechaty, Christopher; Wright, Sandra; Presura, Radu

    2008-04-01

    The interaction of shock waves with inhomogeneous media is important in many astrophysical problems, e.g. the role of shock compression in star formation. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory, to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. Experiments with flyer-generated shock waves have been performed on the Z machine in Sandia. The Zebra accelerator at the Nevada Terawatt Facility (NTF) allows for complementary experiments with high repetition rate. First experiments on Zebra demonstrated flyer acceleration to sufficiently high velocities (around 2 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  7. Raman spectroscopies in shock-compressed materials

    SciTech Connect

    Schmidt, S.C.; Moore, D.S.; Shaner, J.W.

    1983-01-01

    Spontaneous Raman spectroscopy, stimulated Raman scattering and coherent anti-Stokes Raman scattering have been used to measure temperatures and changes in molecular vibrational frequencies for detonating and shocked materials. Inverse Raman and Raman induced Kerr effect spectroscopies have been suggested as diagnostic probes for determining and phenomenology of shock-induced chemical reactions. The practicality, advantages, and disadvantages of using Raman scattering techniques as diagnostic probes of microscopic phenomenology through and immediately behind the shock front of shock-compressed molecular systems are discussed.

  8. Density Shock Waves in Confined Microswimmers

    NASA Astrophysics Data System (ADS)

    Tsang, Alan Cheng Hou; Kanso, Eva

    2016-01-01

    Motile and driven particles confined in microfluidic channels exhibit interesting emergent behavior, from propagating density bands to density shock waves. A deeper understanding of the physical mechanisms responsible for these emergent structures is relevant to a number of physical and biomedical applications. Here, we study the formation of density shock waves in the context of an idealized model of microswimmers confined in a narrow channel and subject to a uniform external flow. Interestingly, these density shock waves exhibit a transition from "subsonic" with compression at the back to "supersonic" with compression at the front of the population as the intensity of the external flow increases. This behavior is the result of a nontrivial interplay between hydrodynamic interactions and geometric confinement, and it is confirmed by a novel quasilinear wave model that properly captures the dependence of the shock formation on the external flow. These findings can be used to guide the development of novel mechanisms for controlling the emergent density distribution and the average population speed, with potentially profound implications on various processes in industry and biotechnology, such as the transport and sorting of cells in flow channels.

  9. Isentropic compressive wave generator and method of making same

    DOEpatents

    Barker, L.M.

    An isentropic compressive wave generator and method of making same are disclosed. The wave generator comprises a disk or flat pillow member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

  10. Microbial Life and Shock Compression - Life or Death?

    NASA Astrophysics Data System (ADS)

    Burchell, Mark

    2005-07-01

    Extreme shock compressions represent a threat to organisms that inhabit planetary surfaces such as rocks. For example, a giant impact on a planetary surface can sterilise the surrounding region by passage of the resulting shock wave. Modelling of the limit of the zone of lethality depends on a knowledge of the response of micro-organisms to extreme shock. Similarly high speed ejecta can be launched into space from an impact site and may carry viable micro-organisms if they can survive the shock of the launch. Or potentially a rocky body arriving from space may introduce life to the Earth, provided the putative organisms can survive the shock of the impact (amongst other hazards). The results of a variety of laboratory experiments on shock compression of micro-organisms will be presented and discussed (with some data from the author and some from the literature). Some of the experiments involved firing spore and microbe laden projectiles at speeds of up to 6 or 7 km s-1 into a variety of targets. Other experiments used flying plate techniques to subject layers of spores to extreme shocks. The conclusion is that micro-organisms can survive extreme shock pressures (10's of GPa) in short duration events, albeit with a very small, but measurable, survival rate. These pressures cover the range likely to be found in giant impacts from space for example.

  11. Magnetically accelerated foils for shock wave experiments

    NASA Astrophysics Data System (ADS)

    Neff, S.; Ford, J.; Wright, S.; Martinez, D.; Plechaty, C.; Presura, R.

    2009-08-01

    Many astrophysical phenomena involve the interaction of a shock wave with an inhomogeneous background medium. Using scaled experiments with inhomogeneous foam targets makes it possible to study relevant physics in the laboratory to better understand the mechanisms of shock compression and to benchmark astrophysical simulation codes. First experiments on Zebra at the Nevada Terawatt Facility (NTF) have demonstrated flyer acceleration to sufficiently high velocities (up to 5 km/s) and that laser shadowgraphy can image sound fronts in transparent targets. Based on this, we designed an optimized setup to improve the flyer parameters (higher speed and mass) to create shock waves in transparent media. Once x-ray backlighting with the Leopard laser at NTF is operational, we will switch to foam targets with parameters relevant for laboratory astrophysics.

  12. Shock Compression of Simulated Adobe

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  13. Stress relaxation in vanadium under shock and shockless dynamic compression

    SciTech Connect

    Kanel, G. I.; Razorenov, S. V.; Garkushin, G. V.; Savinykh, A. S.; Zaretsky, E. B.

    2015-07-28

    Evolutions of elastic-plastic waves have been recorded in three series of plate impact experiments with annealed vanadium samples under conditions of shockless and combined ramp and shock dynamic compression. The shaping of incident wave profiles was realized using intermediate base plates made of different silicate glasses through which the compression waves were entered into the samples. Measurements of the free surface velocity histories revealed an apparent growth of the Hugoniot elastic limit with decreasing average rate of compression. The growth was explained by “freezing” of the elastic precursor decay in the area of interaction of the incident and reflected waves. A set of obtained data show that the current value of the Hugoniot elastic limit and plastic strain rate is rather associated with the rate of the elastic precursor decay than with the local rate of compression. The study has revealed the contributions of dislocation multiplications in elastic waves. It has been shown that independently of the compression history the material arrives at the minimum point between the elastic and plastic waves with the same density of mobile dislocations.

  14. A collisionless shock wave experiment

    SciTech Connect

    Winske, D.; Jones, M.E.; Sgro, A.G.; Thomas, V.A.

    1995-04-01

    Collisionless shock waves are a very important heating mechanism for plasmas and are commonly found in space and astrophysical environments. Collisionless shocks were studied in the laboratory more than 20 years ago, and more recently in space via in situ satellite measurements. The authors propose a new laboratory shock wave experiment to address unresolved issues related to the differences in the partition of plasma heating between electrons and ions in space and laboratory plasmas, which can have important implications for a number of physical systems.

  15. Historical Background of Ultrahigh Pressure Shock Compression Experiments at LLNL: 1973 to 2000

    SciTech Connect

    Nellis, W.J.

    2000-10-09

    My purpose is to recount the historical development of ultrahigh pressure shock compression experiments at LLNL, which I experienced in the period 1973 to 2000. I used several experimental techniques: shock-impedance-match experiments using planar shock waves driven by nuclear explosives (NIMs), the Janus Laser, a railgun, and a two-stage light-gas gun.

  16. Shock wave formation in the collapse of a vapor nanobubble.

    PubMed

    Magaletti, F; Marino, L; Casciola, C M

    2015-02-13

    In this Letter, the dynamics of a collapsing vapor bubble is addressed by means of a diffuse-interface formulation. The model cleanly captures, through a unified approach, all the critical features of the process, such as phase change, transition to supercritical conditions, thermal conduction, compressibility effects, and shock wave formation and propagation. Rather unexpectedly for pure vapor bubbles, the numerical experiments show that the process consists in the oscillation of the bubble associated with the emission of shock waves in the liquid, and with the periodic disappearance and reappearance of the liquid-vapor interface due to transition to super- or subcritical conditions. The results identify the mechanism of shock wave formation as strongly related to the transition of the vapor to the supercritical state, with a progressive steepening of a focused compression wave evolving into a shock which is eventually reflected as an outward propagating wave in the liquid. PMID:25723223

  17. The Interaction of Turbulence with Shock Waves

    SciTech Connect

    Zank, G. P.; Kryukov, I. A.; Pogorelov, N. V.; Shaikh, D.

    2010-03-25

    The heliosheath was expected to be turbulent, the result of upstream turbulence and disturbances (shock waves, pressure and density enhancements, structures, etc.) being transmitted across and interacting with the heliospheric termination shock (HTS). A turbulent heliosheath has indeed been observed downstream of the HTS, but the character of the turbulence is significantly different from that of the solar wind. Here, we discuss the transmission of waves and turbulence across the HTS, both analytically and numerically, in the large plasma beta approximation, and we investigate both small amplitude and large-amplitude cases. We find that the linear theory is a reasonable approximation for small amplitude waves incident on the shock. In the case of large amplitude entropy fluctuations incident on the shock, the downstream state is initially one of coherent wave forms, but this rapidly devolves to a highly disturbed state that evolves eventually to a state dominated by vortical structures. Of particular importance, we find that the HTS generates significant levels of downstream compressible turbulence, even in their absence upstream.

  18. Compressive passive millimeter wave imager

    SciTech Connect

    Gopalsami, Nachappa; Liao, Shaolin; Elmer, Thomas W; Koehl, Eugene R; Heifetz, Alexander; Raptis, Apostolos C

    2015-01-27

    A compressive scanning approach for millimeter wave imaging and sensing. A Hadamard mask is positioned to receive millimeter waves from an object to be imaged. A subset of the full set of Hadamard acquisitions is sampled. The subset is used to reconstruct an image representing the object.

  19. International Shock-Wave Database: Current Status

    NASA Astrophysics Data System (ADS)

    Levashov, Pavel

    2013-06-01

    Shock-wave and related dynamic material response data serve for calibrating, validating, and improving material models over very broad regions of the pressure-temperature-density phase space. Since the middle of the 20th century vast amount of shock-wave experimental information has been obtained. To systemize it a number of compendiums of shock-wave data has been issued by LLNL, LANL (USA), CEA (France), IPCP and VNIIEF (Russia). In mid-90th the drawbacks of the paper handbooks became obvious, so the first version of the online shock-wave database appeared in 1997 (http://www.ficp.ac.ru/rusbank). It includes approximately 20000 experimental points on shock compression, adiabatic expansion, measurements of sound velocity behind the shock front and free-surface-velocity for more than 650 substances. This is still a useful tool for the shock-wave community, but it has a number of serious disadvantages which can't be easily eliminated: (i) very simple data format for points and references; (ii) minimalistic user interface for data addition; (iii) absence of history of changes; (iv) bad feedback from users. The new International Shock-Wave database (ISWdb) is intended to solve these and some other problems. The ISWdb project objectives are: (i) to develop a database on thermodynamic and mechanical properties of materials under conditions of shock-wave and other dynamic loadings, selected related quantities of interest, and the meta-data that describes the provenance of the measurements and material models; and (ii) to make this database available internationally through the Internet, in an interactive form. The development and operation of the ISWdb is guided by an advisory committee. The database will be installed on two mirrored web-servers, one in Russia and the other in USA (currently only one server is available). The database provides access to original experimental data on shock compression, non-shock dynamic loadings, isentropic expansion, measurements of sound

  20. Uniform shock waves in disordered granular matter

    NASA Astrophysics Data System (ADS)

    Gómez, Leopoldo R.; Turner, Ari M.; Vitelli, Vincenzo

    2012-10-01

    The confining pressure P is perhaps the most important parameter controlling the properties of granular matter. Strongly compressed granular media are, in many respects, simple solids in which elastic perturbations travel as ordinary phonons. However, the speed of sound in granular aggregates continuously decreases as the confining pressure decreases, completely vanishing at the jamming-unjamming transition. This anomalous behavior suggests that the transport of energy at low pressures should not be dominated by phonons. In this work we use simulations and theory to show how the response of granular systems becomes increasingly nonlinear as pressure decreases. In the low-pressure regime the elastic energy is found to be mainly transported through nonlinear waves and shocks. We numerically characterize the propagation speed, shape, and stability of these shocks and model the dependence of the shock speed on pressure and impact intensity by a simple analytical approach.

  1. Properties of Fluid Deuterium under Double-Shock Compression to Several Mbar

    SciTech Connect

    Vianello, E; Celliers, P M; Hicks, D G; Boehly, T R; Collins, T B; Moon, S J; Eggert, J H; Collins, G W; Meyerhofer, D D

    2004-02-03

    The compressibility of fluid deuterium up to several Mbar has been probed using laser-driven shock waves reflected from a quartz anvil. Combining high-precision ({approx} 1 %) shock velocity measurements with the double-shock technique, where differences in equation of state (EOS) models are magnified, has allowed us to accurately discriminate between various theoretical predictions. Our data are consistent with EOS models that show approximately fourfold compression on the principal Hugoniot from 0.7 to 1 Mbar; however, our results indicate that deuterium has a higher compressibility than predicted by these models for single shock pressures between 1 and 2.5 Mbar.

  2. Shock compression and initiation behavior of FEFO

    SciTech Connect

    Simpson, R.L.; Helm, F.H.; von Holtz, E.H.

    1988-11-11

    A series of experiments were carried out on FEFO to determine the non-reactive equation of state and initiation sensitivity to one- dimensional shock loading. The material was found to be extremely insensitive requiring approximately 13.0 GPa to initiate it. Pressure records indicate that the build-up to detonation may occur within the FEFO and not at the impactor-sample interface as is often assumed. In addition, it was found that the compression vs. detonation induction time behavior between FEFO and three nitroalkanes are approximately the same although the shock pressure thresholds are quite different. 9 refs., 5 figs., 1 tab.

  3. Planar shock wave sliding over a water layer

    NASA Astrophysics Data System (ADS)

    Rodriguez, V.; Jourdan, G.; Marty, A.; Allou, A.; Parisse, J.-D.

    2016-08-01

    In this work, we conduct experiments to study the interaction between a horizontal free water layer and a planar shock wave that is sliding over it. Experiments are performed at atmospheric pressure in a shock tube with a square cross section (200× 200 mm^2) for depths of 10, 20, and 30 mm; a 1500-mm-long water layer; and two incident planar shock waves having Mach numbers of 1.11 and 1.43. We record the pressure histories and high-speed visualizations to study the flow patterns, surface waves, and spray layers behind the shock wave. We observe two different flow patterns with ripples formed at the air-water interface for the weaker shock wave and the dispersion of a droplet mist for the stronger shock wave. From the pressure signals, we extract the delay time between the arrival of the compression wave into water and the shock wave in air at the same location. We show that the delay time evolves with the distance traveled over the water layer, the depth of the water layer, and the Mach number of the shock wave.

  4. Shock wave interaction with turbulence: Pseudospectral simulations

    SciTech Connect

    Buckingham, A.C.

    1986-12-30

    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.

  5. Shock-compression properties of ceramics

    SciTech Connect

    Grady, D.

    1991-01-01

    High-resolution, time-resolved shock compression measurements have been performed on high-strength monolithic ceramics to assess equation-of-state, phase transformation and flow properties. A substantial base of data has been obtained on a range of ceramics including aluminium nitride, aluminum oxide, boron carbide, silicon carbide, titanium diboride and zirconium dioxide. These data provide material response properties for nonlinear elastic compliance, pressure-induced phase transformation, shear strength and tensile fracture strength. 14 refs., 8 figs.

  6. Shock compression experiments on Lithium Deuteride single crystals.

    SciTech Connect

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

    2014-10-01

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

  7. Shock compression of low-density foams

    SciTech Connect

    Holmes, N.C.

    1993-07-01

    Shock compression of very low density micro-cellular materials allows entirely new regimes of hot fluid states to be investigated experimentally. Using a two-stage light-gas gun to generate strong shocks, temperatures of several eV are readily achieved at densities of roughly 0.5--1 g/cm{sup 3} in large, uniform volumes. The conditions in these hot, expanded fluids are readily found using the Hugoniot jump conditions. We will briefly describe the basic methodology for sample preparation and experimental measurement of shock velocities. We present data for several materials over a range of initial densities. This paper will explore the applications of these methods for investigations of equations of state and phase diagrams, spectroscopy, and plasma physics. Finally, we discus the need for future work on these and related low-density materials.

  8. Belt-snap and towel-snap shock waves

    NASA Astrophysics Data System (ADS)

    Settles, Gary; Hargather, Michael; Lawson, Michael; Bigger, Rory

    2007-11-01

    Traditional simple means of generating shock waves are examined by high-speed imaging. A leather belt is folded upon itself at mid-length and the ends are grasped firmly in each hand. When pushed together a loop forms, and when quickly pulled apart the loop closes rapidly, producing a sharp ``crack'' similar to the cracking of a whip (Shock Waves 8(1), 1998). The towel-snap mimics whip cracking by causing the towel end to rotate supersonically. We investigated these phenomena using a high-speed digital camera (10k and 30k frames/sec, 4 microsec exposure) and a sensitive schlieren optical system of 1m aperture. Results show that compression of the air between the two rapidly-approaching leather belt bands first causes a spherical shock wave to form near one hand. The compression then runs along the belt length toward the other hand at supersonic speed, producing an oblique shock wave that is responsible for the audible crack. In the towel-snap, shock waves are visible from tip motion in open air as well as from the compression due to snapping the towel against a surface. There are no known useful applications of these simple phenomena, but they do address how weak shock waves can be generated by muscle power alone. Several other related examples are also mentioned.

  9. Shock compression of [001] single crystal silicon

    DOE PAGES

    Zhao, S.; Remington, B.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2016-03-14

    Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent withmore » dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Furthermore, application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.« less

  10. Shock compression of [001] single crystal silicon

    NASA Astrophysics Data System (ADS)

    Zhao, S.; Hahn, E. N.; Kad, B.; Remington, B. A.; Bringa, E. M.; Meyers, M. A.

    2016-05-01

    Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent with dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression.

  11. Optical distortion in the field of a lithotripter shock wave

    NASA Astrophysics Data System (ADS)

    Carnell, M. T.; Emmony, D. C.

    1995-10-01

    The schlieren observation of cavitation phenomena produced in the tail of a lithotripter shock wave has indicated the presence of some interesting features. The images produced appear to indicate that cavitation transients in the field of a shock wave propagate nonsymmetrically; this is not the case. The apparent lack of symmetry exhibited by the primary cavitation transients is due to a complex optical lensing effect, which is brought about by the change in refractive index associated with the pressure profile of the shock wave. Objects seen through or immersed in the shock-wave field of an electromagnetic acoustic transducer, such as cavitation, appear highly distorted because of the strong positive and negative lensing effects of the compression and rarefaction cycles of the shock wave. A modification of the schlieren technique called the scale method has been used to model the distortion introduced by the shock wave and consequently explain the cavitation distortion. The technique has also been used to quantitatively analyze and partially reconstruct the lithotripter shock wave. The combination of schlieren and scale imaging gives more information about the refractive index field and therefore the shock-wave structure itself.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    Shock-wave data are presented for liquid helium which has been compressed to densities up to five times greater than the normal liquid. The helium was heated to temperatures up to 21,000 K, while the maximum pressure attained was 56 GPa. The properties of helium and hydrogen are important for modeling the giant planets Saturn and Jupiter where these elements are the major constituents. Conditions on Saturn are of particular interest because studies have suggested that this planet has an internal energy source which is associated with unmixing and gravitational separation of the hydrogen-helium fluid at pressures below 1 TPa. The existence of this phase transition depends very sensitively on the hydrogen and helium equation of state. In the experiments, strong shock waves were generated by the impact of planar projectiles into cryogenic specimen holders.

  13. Shock Compression of Liquid Helium to 56 GPa (560) Kbar

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    Shock-wave data are presented for liquid helium which has been compressed to densities up to five times greater than the normal liquid. The helium was heated to temperatures up to 21,000 K, while the maximum pressure attained was 56 GPa. The properties of helium and hydrogen are important for modeling the giant planets Saturn and Jupiter where these elements are the major constituents. Conditions on Saturn are of particular interest because studies have suggested that this planet has an internal energy source which is associated with unmixing and gravitational separation the hydrogen-helium fluid at pressures below 1 TPa. The existence of this phase transition depends very sensitively on the hydrogen and helium equation of state. In the experiments, strong shock waves were generated by the impact of planar projectiles into cryogenic specimen holders.

  14. Model for shock wave chaos.

    PubMed

    Kasimov, Aslan R; Faria, Luiz M; Rosales, Rodolfo R

    2013-03-01

    We propose the following model equation, u(t) + 1/2(u(2)-uu(s))x = f(x,u(s)) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x = 0 for any t ≥ 0. Here, u(s)(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations. PMID:23521260

  15. Model for shock wave chaos.

    PubMed

    Kasimov, Aslan R; Faria, Luiz M; Rosales, Rodolfo R

    2013-03-01

    We propose the following model equation, u(t) + 1/2(u(2)-uu(s))x = f(x,u(s)) that predicts chaotic shock waves, similar to those in detonations in chemically reacting mixtures. The equation is given on the half line, x<0, and the shock is located at x = 0 for any t ≥ 0. Here, u(s)(t) is the shock state and the source term f is taken to mimic the chemical energy release in detonations. This equation retains the essential physics needed to reproduce many properties of detonations in gaseous reactive mixtures: steady traveling wave solutions, instability of such solutions, and the onset of chaos. Our model is the first (to our knowledge) to describe chaos in shock waves by a scalar first-order partial differential equation. The chaos arises in the equation thanks to an interplay between the nonlinearity of the inviscid Burgers equation and a novel forcing term that is nonlocal in nature and has deep physical roots in reactive Euler equations.

  16. A new shock wave assisted sandalwood oil extraction technique

    NASA Astrophysics Data System (ADS)

    Arunkumar, A. N.; Srinivasa, Y. B.; Ravikumar, G.; Shankaranarayana, K. H.; Rao, K. S.; Jagadeesh, G.

    A new shock wave assisted oil extraction technique from sandalwood has been developed in the Shock Waves Lab, IISc, Bangalore. The fragrant oil extracted from sandalwood finds variety of applications in medicine and perfumery industries. In the present method sandal wood specimens (2.5mm diameter and 25mm in length)are subjected to shock wave loading (over pressure 15 bar)in a constant area shock tube, before extracting the sandal oil using non-destructive oil extraction technique. The results from the study indicates that both the rate of extraction as well as the quantity of oil obtained from sandal wood samples exposed to shock waves are higher (15-40 percent) compared to non-destructive oil extraction technique. The compressive squeezing of the interior oil pockets in the sandalwood specimen due to shock wave loading appears to be the main reason for enhancement in the oil extraction rate. This is confirmed by the presence of warty structures in the cross-section and micro-fissures in the radial direction of the wood samples exposed to shock waves in the scanning electron microscopic investigation. In addition the gas chromatographic studies do not show any change in the q uality of sandal oil extracted from samples exposed to shock waves.

  17. What is a Shock Wave to an Explosive Molecule?

    SciTech Connect

    Tarver, C M

    2001-06-12

    An explosive molecule is a metastable chemical species that reacts exothermically given the correct stimulus. Impacting an explosive with a shock wave is a ''wake-up call'' or ''trigger'' which compresses and heats the molecule. The energy deposited by the shock wave must be distributed to the vibrational modes of the explosive molecule before chemical reaction can occur. If the shock pressure and temperature are high enough and last long enough, exothermic chemical decomposition can lead to the formation of a detonation wave. For gaseous, liquid, and perfect single crystal solid explosives, after an induction time, chemical reaction begins at or near the rear boundary of the charge. This induction time can be calculated by high pressure, high temperature transition state theory. A ''superdetonation'' wave travels through the preshocked explosive until it overtakes the initial shock wave and then slows to the steady state Chapman-Jouguet (C-J) velocity. In heterogeneous solid explosives, initiation of reaction occurs at ''hot spots'' created by shock compression. If there is a sufficient number of large and hot enough ''hot spots,'' these ignition sites grow creating a pressure pulse that overtakes the leading shock front causing detonation. Since the chemical energy is released well behind the leading shock front of a detonation wave, a mechanism is required for this energy to reinforce the leading shock front and maintain its overall constant velocity. This mechanism is the amplification of pressure wavelets in the reaction zone by the process of de-excitation of the initially highly vibrationally excited reaction product molecules. This process leads to the development of the three-dimensional structure of detonation waves observed for all explosives. In a detonation wave, the leading shock wave front becomes a ''burden'' for the explosive molecule to sustain by its chemical energy release.

  18. Shock wave absorber having apertured plate

    DOEpatents

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

    1983-08-26

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  19. Shock wave absorber having apertured plate

    DOEpatents

    Shin, Yong W.; Wiedermann, Arne H.; Ockert, Carl E.

    1985-01-01

    The shock or energy absorber disclosed herein utilizes an apertured plate maintained under the normal level of liquid flowing in a piping system and disposed between the normal liquid flow path and a cavity pressurized with a compressible gas. The degree of openness (or porosity) of the plate is between 0.01 and 0.60. The energy level of a shock wave travelling down the piping system thus is dissipated by some of the liquid being jetted through the apertured plate toward the cavity. The cavity is large compared to the quantity of liquid jetted through the apertured plate, so there is little change in its volume. The porosity of the apertured plate influences the percentage of energy absorbed.

  20. Bow shock and magnetosheath waves at Mercury

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.; Behannon, K. W.

    1975-01-01

    Mariner 10 measurements at the Mercury bow shock provide examples where the magnetic field is approximately parallel or perpendicular to the bow shock normal. Upstream of a broad irregular parallel shock, left hand circularly polarized waves are observed which cut off very sharply at approximately 4 Hz. Upstream of a perpendicular shock, right hand circularly polarized waves are observed which persist up to the Nyquist frequency of 12 Ha. Determination of the wave propagation vector as a function of frequency helps conclusively identify the waves as whistler mode waves propagating from the shock. The magnetosheath downstream of the parallel shock is disturbed more than that downstream of the perpendicular shock particularly below 1 Hz. In the latter case regular left hand polarized waves observed slightly above the proton gyrofrequency are identified as ion cyclotron waves with wavelength approximately 300 km which are Doppler shifted up to their observed frequency.

  1. Corrugation of Relativistic Magnetized Shock Waves

    NASA Astrophysics Data System (ADS)

    Lemoine, Martin; Ramos, Oscar; Gremillet, Laurent

    2016-08-01

    As a shock front interacts with turbulence it develops corrugation, which induces outgoing wave modes in the downstream plasma. For a fast shock wave, the incoming wave modes can either be fast magnetosonic waves originating downstream, outrunning the shock, or eigenmodes of the upstream plasma drifting through the shock. Using linear perturbation theory in relativistic MHD, this paper provides a general analysis of the corrugation of relativistic magnetized fast shock waves resulting from their interaction with small amplitude disturbances. Transfer functions characterizing the linear response for each of the outgoing modes are calculated as a function of the magnetization of the upstream medium and as a function of the nature of the incoming wave. Interestingly, if the latter is an eigenmode of the upstream plasma, we find that there exists a resonance at which the (linear) response of the shock becomes large or even diverges. This result may have profound consequences on the phenomenology of astrophysical relativistic magnetized shock waves.

  2. In-situ probing of lattice response in shock compressed materials using x-ray diffraction

    SciTech Connect

    Hawreliak, J; Butterfield, M; Davies, H; El-Dasher, B; Higginbotham, A; Kalantar, D; Kimminau, G; McNaney, J; Milathianaki, D; Murphy, W; Nagler, B; Lorenzana, H; Park, N; Remington, B; Thorton, L; Whitcher, T; Wark, J; Lorenzana, H

    2007-07-17

    Lattice level measurements of material response under extreme conditions are required to build a phenomenological understanding of the shock response of solids. We have successfully used laser produced plasma x-ray sources coincident with laser driven shock waves to make in-situ measurements of the lattice response during shock compression for both single crystal and polycrystalline materials. Using a detailed analysis of shocked single crystal iron which has undergone the {alpha} - {var_epsilon} phase transition we can constrain the transition mechanism to be consistent with a compression and shuffle of alternate lattice planes.

  3. IN-SITU PROBING OF LATTICE RESPONSE IN SHOCK COMPRESSED MATERIALS USING X-RAY DIFFRACTION

    SciTech Connect

    Hawreliak, James; Butterfield, Martin; El-Dasher, Bassem; Kalantar, Daniel; McNaney, James; Remington, Bruce; Lorenzana, Hector; Davies, Huw; Park, Nigel; Thorton, Lee; Higginbotham, Andrew; Kimminau, Giles; Murphy, William; Nagler, Bob; Whitcher, Thomas; Wark, Justin; Milathianaki, Despina

    2007-12-12

    Lattice level measurements of material response under extreme conditions are required to build a phenomenological understanding of the shock response of solids. We have successfully used laser produced plasma x-ray sources coincident with laser driven shock waves to make in-situ measurements of the lattice response during shock compression for both single crystal and polycrystalline materials. Using a detailed analysis of shocked single crystal iron which has undergone the {alpha}-{epsilon} phase transition we can constrain the transition mechanism to be consistent with a compression and shuffle of alternate lattice planes.

  4. Low Frequency Waves at and Upstream of Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Wilson, L. B.

    2016-02-01

    This chapter focuses on the range of low frequency electromagnetic modes observed at and upstream of collisionless shocks in the heliosphere. It discusses a specific class of whistler mode wave observed immediately upstream of collisionless shock ramps, called a whistler precursor. Though these modes have been (and are often) observed upstream of quasi-parallel shocks, the authors limit their discussion to those observed upstream of quasi-perpendicular shocks. The chapter discusses the various ion velocity distributions observed at and upstream of collisionless shocks. It also introduces some terminology and relevant instabilities for ion foreshock waves. The chapter discusses the most common ultra-low frequency (ULF) wave types, their properties, and their free energy sources. It discusses modes that are mostly Alfvénic (i.e., mostly transverse but can be compressive) in nature.

  5. Nonstandard Analysis and Jump Conditions for Converging Shock Waves

    NASA Technical Reports Server (NTRS)

    Baty, Roy S.; Farassat, Fereidoun; Tucker, Don H.

    2008-01-01

    Nonstandard analysis is an area of modern mathematics which studies abstract number systems containing both infinitesimal and infinite numbers. This article applies nonstandard analysis to derive jump conditions for one-dimensional, converging shock waves in a compressible, inviscid, perfect gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are introduced to model the flow parameters across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters.

  6. Computation of Thermally Perfect Properties of Oblique Shock Waves

    NASA Technical Reports Server (NTRS)

    Tatum, Kenneth E.

    1996-01-01

    A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon a value of cp expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135, and with a state-of-the-art computational fluid dynamics code. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use, and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).

  7. Computation of Thermally Perfect Oblique Shock Wave Properties

    NASA Technical Reports Server (NTRS)

    Tatum, Kenneth E.

    1997-01-01

    A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon the specific heat expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).

  8. Effects of shock structure on temperature field in compressible turbulence

    NASA Astrophysics Data System (ADS)

    Ni, Qionglin; Chen, Shiyi

    2014-11-01

    Effects of shock structure on temperature in compressible turbulence were investigated. The small-scale shocklets and large-scale shock waves were appeared in the flows driven by solenoidal and compressive forcings, i.e. SFT & CFT, respectively. In SFT the temperature had Kolmogorov spectrum and ramp-cliff structures, while in CFT it obeyed Burgers spectrum and was dominated by large-scale rarefaction and compression. The power-law exponents for the p.d.f. of large negative dilatation were -2.5 in SFT and -3.5 in CFT, approximately corresponded to model results. The isentropic approximation of thermodynamic variables showed that in SFT, the isentropic derivation was reinforced when turbulent Mach number increased. At similar turbulent Mach number, the variables in CFT exhibited more anisentropic. It showed that the transport of temperature was increased by the small-scale viscous dissipation and the large-scale pressure-dilatation. The distribution of positive and negative components of pressure-dilatation confirmed the mechanism of negligible pressure-dilatation at small scales. Further, the positive skewness of p.d.f.s of pressure-dilatation implied that the conversion from kinetic to internal energy by compression was more intense than the opposite process by rarefaction.

  9. Inelastic response of silicon to shock compression.

    PubMed

    Higginbotham, A; Stubley, P G; Comley, A J; Eggert, J H; Foster, J M; Kalantar, D H; McGonegle, D; Patel, S; Peacock, L J; Rothman, S D; Smith, R F; Suggit, M J; Wark, J S

    2016-01-01

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature. PMID:27071341

  10. Inelastic response of silicon to shock compression

    DOE PAGES

    Higginbotham, Andrew; Stubley, P. G.; Comley, A. J.; Eggert, J. H.; Foster, J. M.; Kalantar, D. H.; McGonegle, D.; Patel, S.; Peacock, L. J.; Rothman, S. D.; et al

    2016-04-13

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported ‘anomalous’ elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. Lastly, this modelmore » is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.« less

  11. Inelastic response of silicon to shock compression

    PubMed Central

    Higginbotham, A.; Stubley, P. G.; Comley, A. J.; Eggert, J. H.; Foster, J. M.; Kalantar, D. H.; McGonegle, D.; Patel, S.; Peacock, L. J.; Rothman, S. D.; Smith, R. F.; Suggit, M. J.; Wark, J. S.

    2016-01-01

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported ‘anomalous’ elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature. PMID:27071341

  12. Inelastic response of silicon to shock compression.

    PubMed

    Higginbotham, A; Stubley, P G; Comley, A J; Eggert, J H; Foster, J M; Kalantar, D H; McGonegle, D; Patel, S; Peacock, L J; Rothman, S D; Smith, R F; Suggit, M J; Wark, J S

    2016-01-01

    The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.

  13. Calculating Flows With Interfering Shock Waves

    NASA Technical Reports Server (NTRS)

    Glass, Christopher E.

    1993-01-01

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

  14. (BARS) -- Bibliographic Retrieval System, Sandia Shock Compression (SSC) database Shock Physics Index (SPHINX). PC/DOS version 4.0

    SciTech Connect

    Herrmann, W.; Parker, T.J.; Mulholland, K.

    1993-09-01

    The Bibliographic Retrieval System (BARS) is a database management system specially designed to retrieve bibliographic references. Two databases are available, (i) the Sandia Shock Compression (SSC) database which contains over 5600 references to the literature related to stress waves in solids and their applications, and (ii) the Shock Physics Index (SPHINX) which includes over 6200 further references to stress waves in solids, material properties at intermediate and low rates, ballistic and hypervelocity impact, and explosive or shock fabrication methods. There is some overlap in the information in the two data bases.

  15. Tracking the density evolution in counter-propagating shock waves using imaging X-ray scattering

    NASA Astrophysics Data System (ADS)

    Zastrau, U.; Gamboa, E. J.; Kraus, D.; Benage, J. F.; Drake, R. P.; Efthimion, P.; Falk, K.; Falcone, R. W.; Fletcher, L. B.; Galtier, E.; Gauthier, M.; Granados, E.; Hastings, J. B.; Heimann, P.; Hill, K.; Keiter, P. A.; Lu, J.; MacDonald, M. J.; Montgomery, D. S.; Nagler, B.; Pablant, N.; Schropp, A.; Tobias, B.; Gericke, D. O.; Glenzer, S. H.; Lee, H. J.

    2016-07-01

    We present results from time-resolved X-ray imaging and inelastic scattering on collective excitations. These data are then employed to infer the mass density evolution within laser-driven shock waves. In our experiments, thin carbon foils are first strongly compressed and then driven into a dense state by counter-propagating shock waves. The different measurements agree that the graphite sample is about twofold compressed when the shock waves collide, and a sharp increase in forward scattering indicates disassembly of the sample 1 ns thereafter. We can benchmark hydrodynamics simulations of colliding shock waves by the X-ray scattering methods employed.

  16. The History of the APS Shock Compression of Condensed Matter Topical Group

    SciTech Connect

    Forbes, J W

    2001-05-02

    In order to provide broader scientific recognition and to advance the science of shock compressed condensed matter, a group of American Physical Society (APS) members worked within the Society to make this field an active part of the APS. Individual papers were presented at APS meetings starting in the 1940's and shock wave sessions were organized starting with the 1967 Pasadena meeting. Shock wave topical conferences began in 1979 in Pullman, WA. Signatures were obtained on a petition in 1984 from a balanced cross-section of the shock wave community to form an APS Topical Group (TG). The APS Council officially accepted the formation of the Shock Compression of Condensed Matter (SCCM) TG at its October 1984 meeting. This action firmly aligned the shock wave field with a major physical science organization. Most early topical conferences were sanctioned by the APS while those held after 1992 were official APS meetings. The topical group organizes a shock wave topical conference in odd numbered years while participating in shock wave/high pressure sessions at APS general meetings in even numbered years.

  17. Stationary one-dimensional dispersive shock waves.

    PubMed

    Kartashov, Yaroslav V; Kamchatnov, Anatoly M

    2012-02-01

    We address shock waves generated upon the interaction of tilted plane waves with negative refractive index defects in defocusing media with linear gain and two-photon absorption. We found that, in contrast to conservative media where one-dimensional dispersive shock waves usually exist only as nonstationary objects expanding away from a defect or generating beam, the competition between gain and two-photon absorption in a dissipative medium results in the formation of localized stationary dispersive shock waves, whose transverse extent may considerably exceed that of the refractive index defect. One-dimensional dispersive shock waves are stable if the defect strength does not exceed a certain critical value.

  18. Phenomenological description of depoling current in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression: Relaxation model

    NASA Astrophysics Data System (ADS)

    Jiang, Dongdong; Du, Jinmei; Gu, Yan; Feng, Yujun

    2012-05-01

    By assuming a relaxation process for depolarization associated with the ferroelectric (FE) to antiferroelectric (AFE) phase transition in Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3 ferroelectric ceramics under shock wave compression, we build a new model for the depoling current, which is different from both the traditional constant current source (CCS) model and the phase transition kinetics (PTK) model. The characteristic relaxation time and new-equilibrated polarization are dependent on both the shock pressure and electric field. After incorporating a Maxwell s equation, the relaxation model developed applies to all the depoling currents under short-circuit condition and high-impedance condition. Influences of shock pressure, load resistance, dielectric property, and electrical conductivity on the depoling current are also discussed. The relaxation model gives a good description about the suppressing effect of the self-generated electric field on the FE-to-AFE phase transition at low shock pressures, which cannot be described by the traditional models. After incorporating a time- and electric-field-dependent repolarization, this model predicts that the high-impedance current eventually becomes higher than the short-circuit current, which is consistent with the experimental results in the literature. Finally, we make the comparison between our relaxation model and the traditional CCS model and PTK model.

  19. Vorticity and Wave Motion in a Compressible Protoplanetary Disk

    NASA Technical Reports Server (NTRS)

    Davis, Sanford S.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    The impact of an isolated vortex in a compressible Keplerian disk is examined using higher order numerical solutions of the Euler and entropy-conserving Energy equations. The vortex is stretched by the background shear flow with longer lasting anticyclonic vortices persisting for about 10 vortex revolutions. Simultaneously, the vortex emits transient radial waves consisting mainly of axisymmetrical weak shock waves and a slower, nonaxisymmetric Rossby wave. These waves may contribute to certain transient events in protoplanetary disks. The vortex stretching and waves were found to have little long-term feedback on the baseline 'standard solar nebula' disk structure and confirm the extremely stable structure of non self-gravitating disks.

  20. Electron physics in shock waves

    NASA Astrophysics Data System (ADS)

    Kilian, Patrick

    2014-05-01

    The non-relativistic shocks that we find in the solar wind (no matter if driven by CMEs or encounters with planets) are dominated by ion dynamics. Therefore a detailed treatment of electrons is often neglegted to gain significant reductions in computational effort. With recent super computers and massively parallel codes it is possible to perform self-consistent kinetic simulations using particle in cell code. This allows to study the heating of the electrons as well as the acceleration to superthermal energies. These energetic electrons are interesting for couple of reasons. e.g. as an influence on plasma instabilities or for the generation of plasma waves.

  1. Interplanetary shock waves associated with solar flares

    NASA Technical Reports Server (NTRS)

    Chao, J. K.; Sakurai, K.

    1974-01-01

    The interaction of the earth's magnetic field with the solar wind is discussed with emphasis on the influence of solar flares. The geomagnetic storms are considerered to be the result of the arrival of shock wave generated by solar flares in interplanetary space. Basic processes in the solar atmosphere and interplanetary space, and hydromagnetic disturbances associated with the solar flares are discussed along with observational and theoretical problems of interplanetary shock waves. The origin of interplanetary shock waves is also discussed.

  2. On the generation of dispersive shock waves

    NASA Astrophysics Data System (ADS)

    Miller, Peter D.

    2016-10-01

    We review various methods for the analysis of initial-value problems for integrable dispersive equations in the weak-dispersion or semiclassical regime. Some methods are sufficiently powerful to rigorously explain the generation of modulated wavetrains, so-called dispersive shock waves, as the result of shock formation in a limiting dispersionless system. They also provide a detailed description of the solution near caustic curves that delimit dispersive shock waves, revealing fascinating universal wave patterns.

  3. History of the APS Topical Group on Shock Compression of Condensed Matter

    SciTech Connect

    Forbes, J W

    2001-10-19

    In order to provide broader scientific recognition and to advance the science of shock compressed condensed matter, a group of American Physical Society (APS) members worked within the Society to make this field an active part of the APS. Individual papers were presented at APS meetings starting in the 1940's and shock wave sessions were organized starting with the 1967 Pasadena meeting. Shock wave topical conferences began in 1979 in Pullman, WA. Signatures were obtained on a petition in 1984 from a balanced cross-section of the shock wave community to form an APS Topical Group (TG). The APS Council officially accepted the formation of the Shock Compression of Condensed Matter (SCCM) TG at its October 1984 meeting. This action firmly aligned the shock wave field with a major physical science organization. Most early topical conferences were sanctioned by the APS while those held after 1992 were official APS meetings. The topical group organizes a shock wave topical conference in odd numbered years while participating in shock wavehigh pressure sessions at APS general meetings in even numbered years.

  4. IN SITU ELLIPSOMETRY FOR SHOCK COMPRESSION MEASUREMENTS

    SciTech Connect

    Bakshi, L.; Eliezer, S.; Appelbaum, G.; Nissim, N.; Perelmutter, L.; Mond, M.

    2009-12-28

    Knowledge about the optical properties of materials at high pressure and high temperature is needed for EOS research. Ellipsometry measures the change in the polarization of a probe beam reflected from a surface. From the change in polarization, the real and imaginary parts of the time dependent complex index of refraction can be extracted. From the measured optical properties, fundamental physical properties of the material, such as emissivity, phase transitions, and electrical conductivity can be extracted. A dynamic ellipsometry measurement system with nanosecond resolution was built in order to measure all four stocks parameters. Gas gun was used to accelerate the impact flyer. Our experiments concentrated on the optical properties of 1020 steel targets with impact pressure range of 40-250 kbar. Although there are intrinsic difficulties with dynamic ellipsometric measurements, distinct changes were observed for 1020 steel under shock compression larger than 130 kbar, the alpha->epsilon phase transition.

  5. Vibrational spectroscopy in shock-compressed liquids

    SciTech Connect

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

    1992-01-01

    Coherent anti-Stokes Raman spectroscopy is being used to study the structure and energy transfer in simple molecular liquids at the high pressures and temperatures characteristic of explosive detonation. Dense fluids to several thousand degrees temperature and several hundred kilobars pressure are obtained using the shock-compression technique. Vibrational frequencies, third-order susceptibility ratios, and linewidths have been measured for N{sub 2}, O{sub 2}, CO, mixtures of N{sub 2}, O{sub 2}, and CO, and N{sub 2}O. Frequencies are found to increase with pressure. The transition intensity and line-width data suggest that thermal equilibrium of the vibrational levels is attained in less than a few nanoseconds at these high pressures and temperatures. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations.

  6. Vibrational spectroscopy in shock-compressed liquids

    SciTech Connect

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

    1992-03-01

    Coherent anti-Stokes Raman spectroscopy is being used to study the structure and energy transfer in simple molecular liquids at the high pressures and temperatures characteristic of explosive detonation. Dense fluids to several thousand degrees temperature and several hundred kilobars pressure are obtained using the shock-compression technique. Vibrational frequencies, third-order susceptibility ratios, and linewidths have been measured for N{sub 2}, O{sub 2}, CO, mixtures of N{sub 2}, O{sub 2}, and CO, and N{sub 2}O. Frequencies are found to increase with pressure. The transition intensity and line-width data suggest that thermal equilibrium of the vibrational levels is attained in less than a few nanoseconds at these high pressures and temperatures. Vibrational temperatures obtained are compared to those derived from equation-of-state calculations.

  7. Shock compression response of forsterite above 250 GPa.

    PubMed

    Sekine, Toshimori; Ozaki, Norimasa; Miyanishi, Kohei; Asaumi, Yuto; Kimura, Tomoaki; Albertazzi, Bruno; Sato, Yuya; Sakawa, Youichi; Sano, Takayoshi; Sugita, Seiji; Matsui, Takafumi; Kodama, Ryosuke

    2016-08-01

    Forsterite (Mg2SiO4) is one of the major planetary materials, and its behavior under extreme conditions is important to understand the interior structure of large planets, such as super-Earths, and large-scale planetary impact events. Previous shock compression measurements of forsterite indicate that it may melt below 200 GPa, but these measurements did not go beyond 200 GPa. We report the shock response of forsterite above ~250 GPa, obtained using the laser shock wave technique. We simultaneously measured the Hugoniot and temperature of shocked forsterite and interpreted the results to suggest the following: (i) incongruent crystallization of MgO at 271 to 285 GPa, (ii) phase transition of MgO at 285 to 344 GPa, and (iii) remelting above ~470 to 500 GPa. These exothermic and endothermic reactions are seen to occur under extreme conditions of pressure and temperature. They indicate complex structural and chemical changes in the system MgO-SiO2 at extreme pressures and temperatures and will affect the way we understand the interior processes of large rocky planets as well as material transformation by impacts in the formation of planetary systems. PMID:27493993

  8. Shock compression response of forsterite above 250 GPa

    PubMed Central

    Sekine, Toshimori; Ozaki, Norimasa; Miyanishi, Kohei; Asaumi, Yuto; Kimura, Tomoaki; Albertazzi, Bruno; Sato, Yuya; Sakawa, Youichi; Sano, Takayoshi; Sugita, Seiji; Matsui, Takafumi; Kodama, Ryosuke

    2016-01-01

    Forsterite (Mg2SiO4) is one of the major planetary materials, and its behavior under extreme conditions is important to understand the interior structure of large planets, such as super-Earths, and large-scale planetary impact events. Previous shock compression measurements of forsterite indicate that it may melt below 200 GPa, but these measurements did not go beyond 200 GPa. We report the shock response of forsterite above ~250 GPa, obtained using the laser shock wave technique. We simultaneously measured the Hugoniot and temperature of shocked forsterite and interpreted the results to suggest the following: (i) incongruent crystallization of MgO at 271 to 285 GPa, (ii) phase transition of MgO at 285 to 344 GPa, and (iii) remelting above ~470 to 500 GPa. These exothermic and endothermic reactions are seen to occur under extreme conditions of pressure and temperature. They indicate complex structural and chemical changes in the system MgO-SiO2 at extreme pressures and temperatures and will affect the way we understand the interior processes of large rocky planets as well as material transformation by impacts in the formation of planetary systems. PMID:27493993

  9. Shock compression response of forsterite above 250 GPa.

    PubMed

    Sekine, Toshimori; Ozaki, Norimasa; Miyanishi, Kohei; Asaumi, Yuto; Kimura, Tomoaki; Albertazzi, Bruno; Sato, Yuya; Sakawa, Youichi; Sano, Takayoshi; Sugita, Seiji; Matsui, Takafumi; Kodama, Ryosuke

    2016-08-01

    Forsterite (Mg2SiO4) is one of the major planetary materials, and its behavior under extreme conditions is important to understand the interior structure of large planets, such as super-Earths, and large-scale planetary impact events. Previous shock compression measurements of forsterite indicate that it may melt below 200 GPa, but these measurements did not go beyond 200 GPa. We report the shock response of forsterite above ~250 GPa, obtained using the laser shock wave technique. We simultaneously measured the Hugoniot and temperature of shocked forsterite and interpreted the results to suggest the following: (i) incongruent crystallization of MgO at 271 to 285 GPa, (ii) phase transition of MgO at 285 to 344 GPa, and (iii) remelting above ~470 to 500 GPa. These exothermic and endothermic reactions are seen to occur under extreme conditions of pressure and temperature. They indicate complex structural and chemical changes in the system MgO-SiO2 at extreme pressures and temperatures and will affect the way we understand the interior processes of large rocky planets as well as material transformation by impacts in the formation of planetary systems.

  10. Mechanical and optical response of diamond crystals shock compressed along different orientations

    NASA Astrophysics Data System (ADS)

    Lang, John Michael, Jr.

    To determine the mechanical and optical response of diamond crystals at high stresses and to evaluate anisotropy effects, single crystals (Type IIa) were shock compressed along the [100], [110], and [111] orientations to ~120 GPa peak elastic stresses. Particle velocity histories and shock velocities, measured using laser interferometry, were used to examine nonlinear elasticity, refractive indices, and Hugoniot elastic limits of shocked diamond. Time-resolved Raman spectroscopy was used to measure the shock compression induced frequency shifts of the triply degenerate 1332.5 cm-1 Raman line. Longitudinal stress-density states for elastic compression along different orientations were determined from the measured particle velocity histories and elastic shock wave velocities. The complete set of third-order elastic constants was determined from the stress-density states and published acoustic data. Several of these constants differed significantly from those calculated using theoretical models. The refractive index of diamond shocked along [100] and [111] was determined from changes in the optical path length along the direction of uniaxial strain. Linear photoelasticity theory predicted the measured refractive index along [111]. In contrast, the refractive index along [100] was nonlinear. The refractive indices for [110] compression were not determined, but the data showed evidence of birefringence. The splitting and frequency shifts of the diamond Raman line were measured for shock compression along [111] and were in good agreement with predictions from prior shock work. Frequency shifts were also measured along [100] and [110] up to ~60 GPa, extending previous measurements. The anharmonic force constants determined from all shock compression measurements agree with the previous shock compression determinations. Hugoniot elastic limits for diamond shock compressed along different orientations were determined from the measured wave profiles. The elastic limits for

  11. Studies of Shock Wave Interactions with Homogeneous and Isotropic Turbulence

    NASA Technical Reports Server (NTRS)

    Briassulis, G.; Agui, J.; Watkins, C. B.; Andreopoulos, Y.

    1998-01-01

    A nearly homogeneous nearly isotropic compressible turbulent flow interacting with a normal shock wave has been studied experimentally in a large shock tube facility. Spatial resolution of the order of 8 Kolmogorov viscous length scales was achieved in the measurements of turbulence. A variety of turbulence generating grids provide a wide range of turbulence scales. Integral length scales were found to substantially decrease through the interaction with the shock wave in all investigated cases with flow Mach numbers ranging from 0.3 to 0.7 and shock Mach numbers from 1.2 to 1.6. The outcome of the interaction depends strongly on the state of compressibility of the incoming turbulence. The length scales in the lateral direction are amplified at small Mach numbers and attenuated at large Mach numbers. Even at large Mach numbers amplification of lateral length scales has been observed in the case of fine grids. In addition to the interaction with the shock the present work has documented substantial compressibility effects in the incoming homogeneous and isotropic turbulent flow. The decay of Mach number fluctuations was found to follow a power law similar to that describing the decay of incompressible isotropic turbulence. It was found that the decay coefficient and the decay exponent decrease with increasing Mach number while the virtual origin increases with increasing Mach number. A mechanism possibly responsible for these effects appears to be the inherently low growth rate of compressible shear layers emanating from the cylindrical rods of the grid.

  12. SIMULATION OF SHOCK WAVE PROPAGATION AND DAMAGE IN GEOLOGIC MATERIALS

    SciTech Connect

    Lomov, I; Vorobiev, O; Antoun, T H

    2004-09-17

    A new thermodynamically consistent material model for large deformation has been developed. It describes quasistatic loading of limestone as well as high-rate phenomena. This constitutive model has been implemented into an Eulerian shock wave code with adaptive mesh refinement. This approach was successfully used to reproduce static triaxial compression tests and to simulate experiments of blast loading and damage of limestone. Results compare favorably with experimentally available wave profiles from spherically-symmetric explosion in rock samples.

  13. Converging shock wave focusing and interaction with a target

    NASA Astrophysics Data System (ADS)

    Nitishinskiy, M.; Efimov, S.; Antonov, O.; Yanuka, D.; Gurovich, V. Tz.; Bernshtam, V.; Fisher, V.; Krasik, Ya. E.

    2016-04-01

    Converging shock waves in liquids can be used efficiently in the research of the extreme state of matter and in various applications. In this paper, the recent results related to the interaction of a shock wave with plasma preliminarily formed in the vicinity of the shock wave convergence are presented. The shock wave is produced by the underwater electrical explosion of a spherical wire array. The plasma is generated prior to the shock wave's arrival by a low-pressure gas discharge inside a quartz capillary placed at the equatorial plane of the array. Analysis of the Stark broadening of Hα and Hβ spectral lines and line-to-continuum ratio, combined with the ratio of the relative intensities of carbon C III/C II and silicon Si III/Si II lines, were used to determine the plasma density and temperature evolution. It was found that during the first ˜200 ns with respect to the beginning of the plasma compression by the shock wave and when the spectral lines are resolved, the plasma density increases from 2 × 1017 cm-3 to 5 × 1017 cm-3, while the temperature remains at the same value of 3-4 eV. Further, following the model of an adiabatically imploding capillary, the plasma density increases >1019 cm-3, leading to the continuum spectra obtained experimentally, and the plasma temperature >30 eV at radii of compression of ≤20 μm. The data obtained indicate that the shock wave generated by the underwater electrical explosion of a spherical wire array retains its uniformity during the main part of its convergence.

  14. Interaction between a composite compression wave and a vortex in a thermodynamically nonideal medium

    NASA Astrophysics Data System (ADS)

    Konyukhov, A. V.; Likhachev, A. P.; Fortov, V. E.; Oparin, A. M.; Anisimov, S. I.

    2007-04-01

    A numerical analysis is presented of two-dimensional interaction between a transverse vortex and a composite compression wave that can exist in a thermodynamically nonideal medium. It is shown that the interaction of a composite wave involving a “neutrally stable” shock with a vortex generates weakly damped outgoing acoustic waves; i.e., the shock is a source of sound. This phenomenon increases the post-shock acoustic noise level in an initially turbulent flow.

  15. Gigabar shock wave in a laboratory experiment

    NASA Astrophysics Data System (ADS)

    Gus'kov, S. Yu.

    2016-03-01

    The current status of research on generating a powerful shock wave with a pressure of up to several gigabars in a laboratory experiment is reviewed. The focus is on results which give a possibility of shock-wave experiments to study an equation of state of matter (EOS) at the level of gigabar pressure. The proposals are discussed to achieve a plane record-pressure shock wave driven by laser-accelerated fast electrons with respect to EOS-experiment as well as to prospective method of inertial fusion target (ICF) ignition as shock ignition.

  16. Biological Effects of Shock Waves on Infection

    NASA Astrophysics Data System (ADS)

    Gnanadhas, Divya Prakash; Janardhanraj, S.; Chakravortty, Dipshikha; Gopalan, Jagadeesh

    Shock waves have been successfully used for disintegrating kidney stones[1], noninvasive angiogenic approach[2] and for the treatment of osteoporosis[3]. Recently shock waves have been used to treat different medical conditions including intestinal anastomosis[4], wound healing[5], Kienböck's disease[6] and articular cartilage defects[7].

  17. Raman spectroscopy of hypersonic shock waves

    PubMed

    Ramos; Mate; Tejeda; Fernandez; Montero

    2000-10-01

    Raman spectroscopy is shown to be an efficient diagnostic methodology for the study of hypersonic shock waves. As a test, absolute density and rotational population profiles have been measured across five representative normal shock waves of N2 generated in a free jet, spanning the Mach number range 7.7shock waves shows a largely bimodal rotational distribution function with additional contribution of scattered molecules, in close analogy with the velocity distribution function known from helium shock waves [G. Pham-Van-Diep et al., Science 245, 624 (1989)]. Quantitative data on invariance trends of density profiles and properties of the wake beyond the shock waves are reported.

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

    PubMed

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

    2014-02-21

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

  19. Thermophysical properties of multi-shock compressed dense argon

    SciTech Connect

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

    2014-02-21

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

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

    PubMed

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

    2014-02-21

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

  1. Shock waves in the solar system.

    NASA Technical Reports Server (NTRS)

    Spreiter, J. R.

    1972-01-01

    Review of the role of gasdynamic processes involving shock waves in the transfer of solar material and energy to the earth and elsewhere in the solar system. The role of shock waves in maintaining the high temperature of the solar corona and in establishing the steady-state solar wind is discussed. An approximate hydromagnetic theory is developed to explain the flow of a supersonic solar wind past planets and the moon. Data concerning the passage of interplanetary shock waves and the ability of a solar flare to produce such a wave are reviewed, and some terrestrial consequences of solar activity are cited.

  2. Computing unsteady shock waves for aeroacoustic applications

    NASA Technical Reports Server (NTRS)

    Meadows, Kristine R.; Caughey, David A.; Casper, Jay

    1994-01-01

    The computation of unsteady shock waves, which contribute significantly to noise generation in supersonic jet flows, is investigated. The paper focuses on the difficulties of computing slowly moving shock waves. Numerical error is found to manifest itself principally as a spurious entropy wave. Calculations presented are performed using a third-order essentially nonoscillatory scheme. The effect of stencil biasing parameters and of two versions of numerical flux formulas on the magnitude of spurious entropy are investigated. The level of numerical error introduced in the calculation is quantified as a function of shock pressure ratio, shock speed, Courant number, and mesh density. The spurious entropy relative to the entropy jump across a static shock decreases with increasing shock strength and shock velocity relative to the grid, but is insensitive to Courant number. The structure of the spurious entropy wave is affected by the choice of flux formulas and algorithm biasing parameters. The effect of the spurious numerical waves on the calculation of sound amplification by a shock wave is investigated. For this class of problem, the acoustic pressure waves are relatively unaffected by the spurious numerical phenomena.

  3. Computing unsteady shock waves for aeroacoustic applications

    NASA Technical Reports Server (NTRS)

    Meadows,, Kristine r.; Caughey, David A.; Casper, Jay

    1994-01-01

    The computation of unsteady shock waves, which contribute significantly to noise generation in supersonic jet flows, is investigated. This paper focuses on the difficulties of computing slowly moving shock waves. Numerical error is found to manifest itself principally as a spurious entropy wave. Calculations presented are performed using a third order essentially nonoscillatory scheme. The effect of stencil biasing parameters and of two versions of numerical flux formulas on the magnitude of spurious entropy are investigated. The level of numerical error introduced in the calculation in quantified as a function of shock pressure ratio, shock speed, Courant number, and mesh density. The spurious entropy relative to the entropy jump across a static shock decreases with increasing shock strength and shock velocity relative to the grid, but is insensitive to Courant number. The structure of the spurious entropy wave is affected by the choice of flux formulas and algorithm biasing parameters. The effect of the spurious numerical waves on the calculation of sound amplification by a shock wave is investigated. For this class of problem, the acoustic pressure waves are relatively unaffected by the spurious numerical phenomena.

  4. Multiple spherically converging shock waves in liquid deuterium

    SciTech Connect

    Boehly, T. R.; Goncharov, V. N.; Seka, W.; Hu, S. X.; Marozas, J. A.; Meyerhofer, D. D.; Celliers, P. M.; Hicks, D. G.; Barrios, M. A.; Fratanduono, D.; Collins, G. W.

    2011-09-15

    To achieve ignition, inertial confinement fusion target designs use a sequence of shocks to compress the target before it implodes. To minimize the entropy acquired by the fuel, the strength and timing of these shocks will be precisely set during a series of tuning experiments that adjust the laser pulse to achieve optimal conditions. We report measurements of the velocity and timing of multiple, converging shock waves inside spherical targets filled with liquid (cryogenic) deuterium. These experiments produced the highest reported shock velocity observed in liquid deuterium (U{sub s} = 135 km/s at {approx}25 Mb) and observed an increase in shock velocity due to spherical convergence. These direct-drive experiments are best simulated when hydrodynamic codes use a nonlocal model for the transport of absorbed laser energy from the coronal plasma to the ablation surface.

  5. Shock Wave Dynamics in Weakly Ionized Plasmas

    NASA Technical Reports Server (NTRS)

    Johnson, Joseph A., III

    1999-01-01

    An investigation of the dynamics of shock waves in weakly ionized argon plasmas has been performed using a pressure ruptured shock tube. The velocity of the shock is observed to increase when the shock traverses the plasma. The observed increases cannot be accounted for by thermal effects alone. Possible mechanisms that could explain the anomalous behavior include a vibrational/translational relaxation in the nonequilibrium plasma, electron diffusion across the shock front resulting from high electron mobility, and the propagation of ion-acoustic waves generated at the shock front. Using a turbulence model based on reduced kinetic theory, analysis of the observed results suggest a role for turbulence in anomalous shock dynamics in weakly ionized media and plasma-induced hypersonic drag reduction.

  6. International Shock-Wave Database: Systematization of Experimental Data

    NASA Astrophysics Data System (ADS)

    Levashov, Pavel R.; Khishchenko, Konstantin V.; Lomonosov, Igor V.; Minakov, Dmitry V.; Zakharenkov, Alexey S.

    2011-06-01

    In this work, we announce the creation of the International Shock-Wave Database (ISWDB). Shock-wave and related dynamic material response data serve for calibrating, validating, and improving material models over very broad regions of the pressure-temperature-density phase space. Our objectives are (i) to develop a database on thermodynamic and mechanical properties of materials under conditions of shock wave and other dynamic loadings, selected related quantities of interest, and the meta-data that describes the provenance of the measurements and material models, and (ii) to make this database available internationally thru the Internet, in an interactive form. The development and operation of the ISWDB will be guided by input from a steering committee. The database will be installed on two mirrored web-servers, one in Russia and the other in USA. The database will provide access to original experimental data on shock compression, non-shock dynamic loadings, isentropic expansion, measurements of sound speed in the Hugoniot state, and time-dependent free-surface or window-interface velocity profiles. We believe that the ISWDB will be a useful tool for the shock-wave community.

  7. Instability of spherically imploding shock waves

    SciTech Connect

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

    1995-12-31

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

  8. Stability of imploding spherical shock waves

    NASA Astrophysics Data System (ADS)

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

    1995-12-01

    The stability of spherically imploding shock waves is systematically investigated in this letter. The basic state is Guderley and Landau's unsteady self-similar solution of the implosion of a spherical shock wave. The stability analysis is conducted by combining Chandrasekhar's approach to the stability of a viscous liquid drop with Zel'dovich's approach to the stability of spherical flames. The time-dependent amplitudes of the perturbations are obtained analytically by using perturbation method. The relative amplification and decay of the amplitudes of perturbations decides the stability/instability of the spherical imploding shock waves. It is found that the growth rate of perturbations is not in exponential form and near the collapse phase of the shocks, the spherically imploding shock waves are relatively stable.

  9. Stability of imploding spherical shock waves

    SciTech Connect

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

    1995-12-01

    The stability of spherically imploding shock waves is systematically investigated in this letter. The basic state is Guderley and Landau`s unsteady self-similar solution of the implosion of a spherical shock wave. The stability analysis is conducted by combining Chandrasekhar`s approach to the stability of a viscous liquid drop with Zel`dovich`s approach to the stability of spherical flames. The time-dependent amplitudes of the perturbations are obtained analytically by using perturbation method. The relative amplification and decay of the amplitudes of perturbations are obtained analytically by using perturbation method. The relative amplification and decay of the amplitudes of perturbations decides the stability/instability of the spherical imploding shock waves. It is found that the growth rate of perturbations is not in exponential form and near the collapse phase of the shocks, the spherically imploding shock waves are relatively stable. 14 refs., 1 fig.

  10. Possible Implications of Anomalous Shock Wave Behavior for Laser Fusion

    NASA Astrophysics Data System (ADS)

    Bates, Jason W.; Montgomery, David C.

    1997-11-01

    In ``normal'' materials, shocks are compressive because of the inequality (partial^2p / partial V^2)_s> 0, which is, however, not dictated by thermodynamics.(e.g.), Ya. B. Zel'dovich and Yu. P. Raizer, ``Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena,'' (N.Y., Academic Press, 1967), Vol I, pp. 67-69; Vol II, pp. 750-762. In ``anomalous'' materials, the inequality may go the other way, and exotic phenomena result: rarefactive shocks, spreading compressive pulses, and shock wave ``splitting'' or instability.^2,(N. M. Kuznetsov, Sov. Phys. JETP 61), 275 (1985). Materials tend to behave ``anomalously'' in the vicinities of phase transitions. Shock-imploded DT fusion fuels will experience a variety of phase transitions, including melting, vaporization, molecular dissociation, and ionization. Imperfectly explored gas-dynamic problems may require attention to each case. For example, in the shock Hugoniot measurements of Da Silva et al. [Phys. Rev. Lett. 78, 483 (1997)], the high-pressure part of Fig. 4b suggests the possibility of ``anomalous'' behavior.

  11. Shock Wave Application to Cell Cultures

    PubMed Central

    Holfeld, Johannes; Tepeköylü, Can; Kozaryn, Radoslaw; Mathes, Wolfgang; Grimm, Michael; Paulus, Patrick

    2014-01-01

    Shock waves nowadays are well known for their regenerative effects. Basic research findings showed that shock waves do cause a biological stimulus to target cells or tissue without any subsequent damage. Therefore, in vitro experiments are of increasing interest. Various methods of applying shock waves onto cell cultures have been described. In general, all existing models focus on how to best apply shock waves onto cells. However, this question remains: What happens to the waves after passing the cell culture? The difference of the acoustic impedance of the cell culture medium and the ambient air is that high, that more than 99% of shock waves get reflected! We therefore developed a model that mainly consists of a Plexiglas built container that allows the waves to propagate in water after passing the cell culture. This avoids cavitation effects as well as reflection of the waves that would otherwise disturb upcoming ones. With this model we are able to mimic in vivo conditions and thereby gain more and more knowledge about how the physical stimulus of shock waves gets translated into a biological cell signal (“mechanotransduction"). PMID:24747842

  12. Dynamics of polymer response to nanosecond shock compression

    NASA Astrophysics Data System (ADS)

    Banishev, Alexandr A.; Shaw, William L.; Curtis, Alexander D.; Dlott, Dana D.

    2014-03-01

    The high strain rate mechanical dynamics of a polymer under shock compression, poly-methyl methacrylate (PMMA, MW = 996 000), were probed in experiments that combined two measurement techniques. The km s-1 impacts with laser-launched flyer plates were characterized by a fast interferometer, and the polymer dynamics were characterized by the nanosecond emission redshifting of Rhodamine 6G dye in PMMA. The thicknesses and velocities of the flyer plates were varied to create shock durations in the 5-22 ns range and pressures in the 2.6-9.2 GPa range. The strain rates were on the order of 107 s-1. With shock durations greater than 10 ns, a two-part rise of the redshift transients was observed, which was interpreted with reference to the well-known viscoelastic shock compression paradigm. However, the initial compression stage, lasting ˜10 ns, was found to be only partially elastic. With an elastic compression, after a shock the density should promptly return to its initial value. But even with the shortest-duration 5 ns shocks, the density relaxation after the shock ended was quite small. The critical shear stress where PMMA loses strength and the viscous compression process begins, appeared to be considerably larger with nanosecond shocks than with microsecond shocks. The loss of strength always took ˜10 ns, and could not be accelerated by increasing the shock pressure, suggesting the rate of strength loss was limited by the need for collective motions of the 30-40 nm polymer chains. The rates and amplitudes of the viscous density relaxation process increased with shock duration and shock pressure.

  13. Measurement of density, temperature, and electrical conductivity of a shock-compressed nonideal nitrogen plasma in the megabar pressure range

    SciTech Connect

    Mochalov, M. A.; Zhernokletov, M. V.; Il'kaev, R. I.; Mikhailov, A. L.; Fortov, V. E.; Gryaznov, V. K.; Iosilevskiy, I. L.; Mezhevov, A. B.; Kovalev, A. E.; Kirshanov, S. I.; Grigor'eva, Yu. A.; Novikov, M. G.; Shuikin, A. N.

    2010-01-15

    Kinematic and thermodynamic parameters of shock-compressed liquid nitrogen are measured behind the front of a plane shock wave using plane wave and hemispherical shock wave generators. In these experiments, high values of compression parameters (shock-compressed hydrogen density {approx} 3.25 g/cm{sup 3} and temperature T{approx} 56000 K at a pressure of P {approx} 265 GPa) are attained. The density, pressure, temperature, and electrical conductivity of the nonideal plasma of shock-compressed liquid nitrogen are measured. A nearly isochoric behavior of the nitrogen shock adiabat is observed in the pressure range P = 100-300 GPa. The thermodynamics of shock-compressed nitrogen is an alyzed using the model of the equation of state in the quasi-chemical representation (SAHA code) as well as the semiempirical wide-range equation of state developed at the Institute of Experimental Physics. Experimental results are interpreted on the basis of calculations as the fixation of the boundary of transition of shock-compressed nitrogen from the polymer phase to the state of a strongly nonideal plasma at P {approx} 100 GPa, {approx} 3.4 g/cm{sup 3}.

  14. Application of shock waves in medicine.

    PubMed

    Thiel, M

    2001-06-01

    Extracorporeal-generated shock waves were introduced approximately 20 years ago to disintegrate kidney stones. This treatment method substantially changed the treatment of urolithiasis. Shock waves have become the treatment of choice for kidney and ureteral stones. Urology, however, is not the only medical field for the potential use of shock waves for problems. Shock waves subsequently have been used in orthopaedics and traumatology to treat various insertional tendinopathies (enthesiopathies) and delayed unions and nonunions of fracture. Shock wave application also has been used in the treatment of tendinopathies in veterinary conditions (race horses). The concept of orthopaedic disorders is that shock waves stimulate or reactivate healing processes in tendons, surrounding tissue and bones, probably through microdisruption of avascular or minimally vascular tissues to encourage revascularization, release of local growth factors, and the recruitment of appropriate stem cells conducive to more normal tissue healing. The current author will give an overview of history and basic research of the application of shock waves in medicine. PMID:11400881

  15. Overview of shock waves in medicine

    NASA Astrophysics Data System (ADS)

    Cleveland, Robin O.

    2003-10-01

    A brief overview of three applications of shock waves is presented. Shock wave lithotripsy (SWL) has been in clinical use for more than 20 years. In the United States it is used to treat more than 80% of kidney stone cases and has wide acceptance with patients because it is a noninvasive procedure. Despite SWLs enormous success there is no agreement on how shock waves comminute stones. There is also a general acceptance that shock waves lead to trauma to the soft tissue of the kidney. Yet there has been little forward progress in developing lithotripters which provide comminution with less side-effects, indeed the original machine is still considered the gold standard. The last decade has seen the advent of new shock wave devices for treating principally musculoskeletal indications, such as plantar fasciitis, tennis elbow, and bone fractures that do not heal. This is referred to as shock wave therapy (SWT). The mechanisms by which SWT works are even less well understood than SWL and the consequences of bioeffects have also not been studied in detail. Shock waves have also been shown to be effective at enhancing drug delivery into cells and assisting with gene transfection. [Work partially supported by NIH.

  16. Evolution Of Nonlinear Waves in Compressing Plasma

    SciTech Connect

    P.F. Schmit, I.Y. Dodin, and N.J. Fisch

    2011-05-27

    Through particle-in-cell simulations, the evolution of nonlinear plasma waves is examined in one-dimensional collisionless plasma undergoing mechanical compression. Unlike linear waves, whose wavelength decreases proportionally to the system length L(t), nonlinear waves, such as solitary electron holes, conserve their characteristic size {Delta} during slow compression. This leads to a substantially stronger adiabatic amplification as well as rapid collisionless damping when L approaches {Delta}. On the other hand, cessation of compression halts the wave evolution, yielding a stable mode.

  17. Refraction index of shock compressed water in the megabar pressure range

    NASA Astrophysics Data System (ADS)

    Batani, D.; Jakubowska, K.; Benuzzi-Mounaix, A.; Cavazzoni, C.; Danson, C.; Hall, T.; Kimpel, M.; Neely, D.; Pasley, J.; Rabec Le Gloahec, M.; Telaro, B.

    2015-11-01

    We compressed water to megabar pressures by laser-driven shock waves and evidenced transparent, opaque and reflecting phases as pressure increases. The refraction index of water in the first two states was measured using a VISAR system. At high compression a sharp increase of the real and imaginary part of the refraction index is observed. Experiments were performed at the LULI and RAL laboratories.

  18. Shock waves in strongly coupled plasmas

    SciTech Connect

    Khlebnikov, Sergei; Kruczenski, Martin; Michalogiorgakis, Georgios

    2010-12-15

    Shock waves are supersonic disturbances propagating in a fluid and giving rise to dissipation and drag. Weak shocks, i.e., those of small amplitude, can be well described within the hydrodynamic approximation. On the other hand, strong shocks are discontinuous within hydrodynamics and therefore probe the microscopics of the theory. In this paper, we consider the case of the strongly coupled N=4 plasma whose microscopic description, applicable for scales smaller than the inverse temperature, is given in terms of gravity in an asymptotically AdS{sub 5} space. In the gravity approximation, weak and strong shocks should be described by smooth metrics with no discontinuities. For weak shocks, we find the dual metric in a derivative expansion, and for strong shocks we use linearized gravity to find the exponential tail that determines the width of the shock. In particular, we find that, when the velocity of the fluid relative to the shock approaches the speed of light v{yields}1 the penetration depth l scales as l{approx}(1-v{sup 2}){sup 1/4}. We compare the results with second-order hydrodynamics and the Israel-Stewart approximation. Although they all agree in the hydrodynamic regime of weak shocks, we show that there is not even qualitative agreement for strong shocks. For the gravity side, the existence of shock waves implies that there are disturbances of constant shape propagating on the horizon of the dual black holes.

  19. Shock wave control using liquid curtains

    NASA Astrophysics Data System (ADS)

    Colvert, Brendan; Tao, Xingtian; Eliasson, Veronica

    2014-11-01

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

  20. Limiting Temperatures of Spherical Shock Wave Implosion.

    PubMed

    Liverts, Michael; Apazidis, Nicholas

    2016-01-01

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

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

    SciTech Connect

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

    1984-09-24

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

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

    NASA Technical Reports Server (NTRS)

    Roberts, W. W., Jr.

    1977-01-01

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

  3. Shock waves on complex networks

    PubMed Central

    Mones, Enys; Araújo, Nuno A. M.; Vicsek, Tamás; Herrmann, Hans J.

    2014-01-01

    Power grids, road maps, and river streams are examples of infrastructural networks which are highly vulnerable to external perturbations. An abrupt local change of load (voltage, traffic density, or water level) might propagate in a cascading way and affect a significant fraction of the network. Almost discontinuous perturbations can be modeled by shock waves which can eventually interfere constructively and endanger the normal functionality of the infrastructure. We study their dynamics by solving the Burgers equation under random perturbations on several real and artificial directed graphs. Even for graphs with a narrow distribution of node properties (e.g., degree or betweenness), a steady state is reached exhibiting a heterogeneous load distribution, having a difference of one order of magnitude between the highest and average loads. Unexpectedly we find for the European power grid and for finite Watts-Strogatz networks a broad pronounced bimodal distribution for the loads. To identify the most vulnerable nodes, we introduce the concept of node-basin size, a purely topological property which we show to be strongly correlated to the average load of a node. PMID:24821422

  4. The microphysics of collisionless shock waves

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  5. The microphysics of collisionless shock waves.

    PubMed

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

    2016-04-01

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

  6. Stability of shock waves in high temperature plasmas

    SciTech Connect

    Das, Madhusmita; Bhattacharya, Chandrani; Menon, S. V. G.

    2011-10-15

    The Dyakov-Kontorovich criteria for spontaneous emission of acoustic waves behind shock fronts are investigated for high temperature aluminum and beryllium plasmas. To this end, the Dyakov and critical stability parameters are calculated from Rankine-Hugoniot curves using a more realistic equation of state (EOS). The cold and ionic contributions to the EOS are obtained via scaled binding energy and mean field theory, respectively. A screened hydrogenic model, including l-splitting, is used to calculate the bound electron contribution to the electronic EOS. The free electron EOS is obtained from Fermi-Dirac statistics. Predictions of the model for ionization curves and shock Hugoniot are found to be in excellent agreement with available experimental and theoretical data. It is observed that the electronic EOS has significant effect on the stability of the planar shock front. While the shock is stable for low temperatures and pressures, instability sets in as temperature rises. The basic reason is ionization of electronic shells and consequent increase in electronic specific heat. The temperatures and densities of the unstable region correspond to those where electronic shells get ionized. With the correct modeling of bound electrons, we find that shock instability for Al occurs at a compression ratio {approx}5.4, contrary to the value {approx}3 reported in the literature. Free electrons generated in the ionization process carry energy from the shock front, thereby giving rise to spontaneously emitted waves, which decay the shock front.

  7. Dispersive shock waves with nonlocal nonlinearity.

    PubMed

    Barsi, Christopher; Wan, Wenjie; Sun, Can; Fleischer, Jason W

    2007-10-15

    We consider dispersive optical shock waves in nonlocal nonlinear media. Experiments are performed using spatial beams in a thermal liquid cell, and results agree with a hydrodynamic theory of propagation.

  8. Shock waves in a dilute granular gas

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  9. Existence Regions of Shock Wave Triple Configurations

    ERIC Educational Resources Information Center

    Bulat, Pavel V.; Chernyshev, Mikhail V.

    2016-01-01

    The aim of the research is to create the classification for shock wave triple configurations and their existence regions of various types: type 1, type 2, type 3. Analytical solutions for limit Mach numbers and passing shock intensity that define existence region of every type of triple configuration have been acquired. The ratios that conjugate…

  10. Compression algorithm for multideterminant wave functions.

    PubMed

    Weerasinghe, Gihan L; Ríos, Pablo López; Needs, Richard J

    2014-02-01

    A compression algorithm is introduced for multideterminant wave functions which can greatly reduce the number of determinants that need to be evaluated in quantum Monte Carlo calculations. We have devised an algorithm with three levels of compression, the least costly of which yields excellent results in polynomial time. We demonstrate the usefulness of the compression algorithm for evaluating multideterminant wave functions in quantum Monte Carlo calculations, whose computational cost is reduced by factors of between about 2 and over 25 for the examples studied. We have found evidence of sublinear scaling of quantum Monte Carlo calculations with the number of determinants when the compression algorithm is used.

  11. Solitary and shock waves in discrete double power law materials

    NASA Astrophysics Data System (ADS)

    Herbold, Eric; Nesterenko, Vitali

    2007-06-01

    A novel strongly nonlinear metamaterial is composed using a periodic arrangement of toroidal rings between plates. The toroids are considered massless strongly nonlinear springs where the force versus displacement relationship is described by two additive power-law relationships. In these systems the nonlinearity is due to the dramatic change of the contact plane, which starts as an arbitrarily thin circle then increases in thickness with increasing compression. Solitary and shock waves are examined numerically and experimentally using three different types of polymer or rubber o-rings allowing mitigation of higher amplitude shock impulses in comparison with granular systems. In these systems a train of pulses can consist of two separate groups related to two strongly nonlinear regimes with different values of exponents, depending on the amplitude. In experiments two types of shock waves (monotonic or oscillatory) were observed depending on the type of o-rings.

  12. Dynamic Shock Compression of Copper to Multi-Megabar Pressure

    NASA Astrophysics Data System (ADS)

    Haill, T. A.; Furnish, M. D.; Twyeffort, L. L.; Arrington, C. L.; Lemke, R. W.; Knudson, M. D.; Davis, J.-P.

    2015-11-01

    Copper is an important material for a variety of shock and high energy density applications and experiments. Copper is used as a standard reference material to determine the EOS properties of other materials. The high conductivity of copper makes it useful as an MHD driver layer in high current dynamic materials experiments on Sandia National Laboratories Z machine. Composite aluminum/copper flyer plates increase the dwell time in plate impact experiments by taking advantage of the slower wave speeds in copper. This presentation reports on recent efforts to reinstate a composite Al/Cu flyer capability on Z and to extend the range of equation-of-state shock compression data through the use of hyper-velocity composite flyers and symmetric planar impact with copper targets. We will present results from multi-dimensional ALEGRA MHD simulations, as well as experimental designs and methods of composite flyer fabrication. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. DOE's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  13. Thermal transport in shock wave–compressed solids using pulsed laser heating

    SciTech Connect

    La Lone, B. M. Capelle, G.; Stevens, G. D.; Turley, W. D.; Veeser, L. R.

    2014-07-15

    A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ∼25 GPa and ∼1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

  14. Finite Mach number spherical shock wave, application to shock ignition

    NASA Astrophysics Data System (ADS)

    Vallet, A.; Ribeyre, X.; Tikhonchuk, V.

    2013-08-01

    A converging and diverging spherical shock wave with a finite initial Mach number Ms0 is described by using a perturbative approach over a small parameter Ms-2. The zeroth order solution is the Guderley's self-similar solution. The first order correction to this solution accounts for the effects of the shock strength. Whereas it was constant in the Guderley's asymptotic solution, the amplification factor of the finite amplitude shock Λ(t)∝dUs/dRs now varies in time. The coefficients present in its series form are iteratively calculated so that the solution does not undergo any singular behavior apart from the position of the shock. The analytical form of the corrected solution in the vicinity of singular points provides a better physical understanding of the finite shock Mach number effects. The correction affects mainly the flow density and the pressure after the shock rebound. In application to the shock ignition scheme, it is shown that the ignition criterion is modified by more than 20% if the fuel pressure prior to the final shock is taken into account. A good agreement is obtained with hydrodynamic simulations using a Lagrangian code.

  15. Finite Mach number spherical shock wave, application to shock ignition

    SciTech Connect

    Vallet, A.; Ribeyre, X.; Tikhonchuk, V.

    2013-08-15

    A converging and diverging spherical shock wave with a finite initial Mach number M{sub s0} is described by using a perturbative approach over a small parameter M{sub s}{sup −2}. The zeroth order solution is the Guderley's self-similar solution. The first order correction to this solution accounts for the effects of the shock strength. Whereas it was constant in the Guderley's asymptotic solution, the amplification factor of the finite amplitude shock Λ(t)∝dU{sub s}/dR{sub s} now varies in time. The coefficients present in its series form are iteratively calculated so that the solution does not undergo any singular behavior apart from the position of the shock. The analytical form of the corrected solution in the vicinity of singular points provides a better physical understanding of the finite shock Mach number effects. The correction affects mainly the flow density and the pressure after the shock rebound. In application to the shock ignition scheme, it is shown that the ignition criterion is modified by more than 20% if the fuel pressure prior to the final shock is taken into account. A good agreement is obtained with hydrodynamic simulations using a Lagrangian code.

  16. Origin of compression-induced failure in brittle solids under shock loading

    NASA Astrophysics Data System (ADS)

    Huang, J. Y.; Li, Y.; Liu, Q. C.; Zhou, X. M.; Liu, L. W.; Liu, C. L.; Zhu, M. H.; Luo, S. N.

    2015-10-01

    The origin of compression-induced failure in brittle solids has been a subject of debate. Using in situ, high-speed, strain field mapping of a representative material, polymethylmethacrylate, we reveal that shock loading leads to heterogeneity in a compressive strain field, which in turn gives rise to localized lateral tension and shear through Poisson's effects, and, subsequently, localized microdamage. A failure wave nucleates from the impact surface and its propagation into the microdamage zone is self-sustained, triggering interior failure. Its velocity increases with increasing shock strength and eventually approaches the shock velocity. The seemingly puzzling phenomena observed in previous experiments, including incubation time, failure wave velocity variations, and surface roughness effects, can all be explained consistently with the nucleation and growth of the microdamage, and the effects of loading strength and preexisting defects.

  17. Shock compression of condensed matter using Eulerian multimaterial method: Applications to multidimensional shocks, deflagration, detonation, and laser ablation

    SciTech Connect

    Yoh, Jack J.; Kim, Ki-hong

    2008-06-01

    The reactive flow analysis of high energy material is performed using hydro shock compression of condensed matter (SCCM) tool that is being developed for handling complex multimaterial dynamics involving energetic and inert matters. Typically, the reacting flows of high energy materials such as fires and explosions give rise to strong nonlinear shock waves and high strain rate deformation of metallic confinements at unusually high pressure and temperature. In order to address difficulties associated with analyzing such complex systems, we have developed a suite of modeling capabilities for elegantly handling large gradients and high strain rates in solids as well as reactive shock waves present in gaseous phase. Mathematical formulation of explosive dynamics involving condensed matter is explained with an emphasis on validating and application of hydro-SCCM to a series of problems of high-speed multimaterial dynamics in nature. A detailed numerical description of a level-set based reactive ghost fluid approach is reported in a separate paper.

  18. Shock-wave dynamics during oil-filled transformer explosions

    NASA Astrophysics Data System (ADS)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Utkin, A. V.

    2016-08-01

    This paper presents a numerical and experimental study of the shock-wave processes evolving inside a closed vessel filled with mineral oil. Obtained experimental Hugoniot data for oil are compared with the corresponding data for water. It is found that compression of mineral oil and water can be described by approximately the same Hugoniot over a wide pressure range. Such similarity allows the use of water instead of mineral oil in the transformer explosion experiments and to describe the compression processes in both liquids using similar equations of state. The Kuznetsov equation of state for water is adopted for a numerical study of mineral oil compression. The features of the evolution of shock waves within mineral oil are analyzed using two-dimensional numerical simulations. Numerical results show that different energy sources may cause different scenarios of loading on the shell. The principal point is the phase transition taking place at relatively high temperatures for the case of high-power energy sources. In this case, a vapor-gaseous bubble emerges that qualitatively changes the dynamics of compression waves and the pattern of loads induced on the shell. Taking into account the features of the process together with the concept of water-oil similarity, the present work presents a new approach for experimental modeling of transformer shell destruction using an explosion with given characteristics in a water-filled shell.

  19. Weak shock wave reflection from concave surfaces

    NASA Astrophysics Data System (ADS)

    Gruber, Sebastien; Skews, Beric

    2013-07-01

    The reflection of very weak shock waves from concave curved surfaces has not been well documented in the past, and recent studies have shown the possible existence of a variation in the accepted reflection configuration evolution as a shock wave encounters an increasing gradient on the reflecting surface. The current study set out to investigate this anomaly using high-resolution photography. Shock tube tests were done on various concave circular and parabolic geometries, all with zero initial ramp angle. Although the results have limitations due to the achievable image resolution, the results indicate that for very weak Mach numbers, M S < 1.1, there may be a region in which the reflection configuration resembles that of a regular reflection, unlike for the stronger shock wave case. This region exists after the triple point of the Mach reflection meets the reflecting surface and prior to the formation of the additional shock structures that represent a transitioned regular reflection. The Mach and transitioned regular reflections at 1.03 < M s < 1.05 also exhibit no signs of a visible shear layer, or a clear discontinuity at the triple point, and are thus also apparently different in the weak shock regime than what has been described for stronger shocks, similar to what has been shown for weak shocks reflecting off a plane wedge.

  20. Turbulence in argon shock waves

    NASA Technical Reports Server (NTRS)

    Johnson, J. A., III; Santiago, J. P.; I, L.

    1981-01-01

    Irregular density fluctuations with turbulent-like behaviors are found in ionizing shock fronts produced by an arc-driven shock tube. Electric probes are used as the primary diagnostic. Spectral analyses show statistical patterns which seem frozen-in and characterizable by a dominant mode and its harmonics.

  1. Whistler waves observed upstream from collisionless shocks

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.

    1973-01-01

    Waves in the frequency range 0.5 - 4 Hz were studied in the region upstream of the earth's bow shock using data from the fluxgate magnetic field experiment on IMP-6. Analysis of 150 examples of these waves during a three month interval indicates that amplitudes are generally less than 1 or 2 gammas and propagation directions generally make angles of between 20 and 40 degrees with the field direction. The waves as measured in the spacecraft frame of reference are either left or right hand polarized with respect to the average field direction. It is concluded that the observed waves are right handed waves in the plasma frame of reference with wavelengths of approximately 100 km propagating upstream in the whistler mode. Doppler shifting reduces the observed frequencies in the spacecraft frame and reverses the observed polarization for those waves propagating more directly upstream. Similar waves are seen ahead of most interplanetary shocks.

  2. Thermodynamics, compressibility, and phase diagram: shock compression of supercritical fluid xenon.

    PubMed

    Zheng, J; Chen, Q F; Gu, Y J; Chen, Z Y; Li, C J

    2014-09-28

    Supercritical fluids have intriguing behaviors at extreme pressure and temperature conditions, prompting the need for thermodynamic properties of supercritical fluid xenon (SCF) under shock compression. Double-shock experimental data on SCF xenon in the 140 GPa pressure range were directly measured by means of a multi-channel pyrometer and a Doppler-pins-system. It entered the so-called warm dense region. We found that the shock compressed SCF Xe had higher dynamic compression and higher number density than that of liquid Xe at same shock pressure. The larger compressibility of SCF Xe in our experiments could be explained that the increase of electronic excitations and ionizations leaded to a large drop of thermal pressure and a softening of Hugoniot. The high pressure phase diagram of xenon was depicted with the aid of the degeneracy, coupling parameter, and current available experiments on the pressure-temperature plane. PMID:25273430

  3. Stishovite: Synthesis by shock wave

    USGS Publications Warehouse

    De Carli, P. S.; Milton, D.J.

    1965-01-01

    Small amounts of stishovite were separated from specimens of explosively shocked sandstones, novaculite, and single-crystal quartz. Estimated peak pressures for the syntheses ranged from 150 to 280 kilobars, and shock temperatures were from 150?? to 900??C. No coesite was detected in any sample. It is suggested that quartz can invert during shock to a short-range-order phase, with sixfold coordination. A small portion of this phase may develop the long-range order of stishovite, and, during the more protracted decrease of the pressure pulse through the stability field of coesite accompanying meteorite crater formation, a portion may invert to coesite.

  4. Transmission of light waves through normal shocks.

    PubMed

    Hariharan, S I; Johnson, D K

    1995-11-20

    We seek to characterize light waves transmitted through normal shock waves. The investigation is motivated by the need for a theory to support a shadowgraph experiment for flow in a convergent-divergent nozzle. In this experiment light beams are passed through the nozzle transverse to the direction of the flow in which a shock has formed in the vicinity of the throat. We present a formulation and an approximation that yield calculations of the intensity of transmitted waves. We also present experimental results to support the theory. The patterns predicted by the theory compare well with the patterns observed in experiments.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Isentropic compressive wave generator impact pillow and method of making same

    DOEpatents

    Barker, Lynn M.

    1985-01-01

    An isentropic compressive wave generator and method of making same. The w generator comprises a disk or flat "pillow" member having component materials of different shock impedances formed in a configuration resulting in a smooth shock impedance gradient over the thickness thereof for interpositioning between an impactor member and a target specimen for producing a shock wave of a smooth predictable rise time. The method of making the pillow member comprises the reduction of the component materials to a powder form and forming the pillow member by sedimentation and compressive techniques.

  7. Turbulent water coupling in shock wave lithotripsy.

    PubMed

    Lautz, Jaclyn; Sankin, Georgy; Zhong, Pei

    2013-02-01

    Previous studies have demonstrated that stone comminution decreases with increased pulse repetition frequency as a result of bubble proliferation in the cavitation field of a shock wave lithotripter (Pishchalnikov et al 2011 J. Acoust. Soc. Am. 130 EL87-93). If cavitation nuclei remain in the propagation path of successive lithotripter pulses, especially in the acoustic coupling cushion of the shock wave source, they will consume part of the incident wave energy, leading to reduced tensile pressure in the focal region and thus lower stone comminution efficiency. We introduce a method to remove cavitation nuclei from the coupling cushion between successive shock exposures using a jet of degassed water. As a result, pre-focal bubble nuclei lifetime quantified by B-mode ultrasound imaging was reduced from 7 to 0.3 s by a jet with an exit velocity of 62 cm s(-1). Stone fragmentation (percent mass <2 mm) after 250 shocks delivered at 1 Hz was enhanced from 22 ± 6% to 33 ± 5% (p = 0.007) in water without interposing tissue mimicking materials. Stone fragmentation after 500 shocks delivered at 2 Hz was increased from 18 ± 6% to 28 ± 8% (p = 0.04) with an interposing tissue phantom of 8 cm thick. These results demonstrate the critical influence of cavitation bubbles in the coupling cushion on stone comminution and suggest a potential strategy to improve the efficacy of contemporary shock wave lithotripters.

  8. Application of Underwater Shock Wave Focusing to the Development of Extracorporeal Shock Wave Lithotripsy

    NASA Astrophysics Data System (ADS)

    Takayama, Kazuyoshi

    1993-05-01

    This paper describes a summary of a research project for the development of extracorporeal shock wave lithotripsy (ESWL), which has been carried out, under close collaboration between the Shock Wave Research Center of Tohoku University and the School of Medicine, Tohoku University. The ESWL is a noninvasive clinical treatment of disintegrating human calculi and one of the most peaceful applications of shock waves. Underwater spherical shock waves were generated by explosion of microexplosives. Characteristics of the underwater shock waves and of ultrasound focusing were studied by means of holographic interferometric flow visualization and polyvinyliden-difluoride (PVDF) pressure transducers. These focused pressures, when applied to clinical treatments, could effectively and noninvasively disintegrate urinary tract stones or gallbladder stones. However, despite clincal success, tissue damage occurs during ESWL treatments, and the possible mechanism of tissue damage is briefly described.

  9. Damage mechanisms in shock wave lithotripsy (SWL)

    NASA Astrophysics Data System (ADS)

    Lokhandwalla, Murtuza

    Shock wave lithotripsy is a 'non-invasive' therapy for treating kidney stones. Focused shock waves fragment stones to a size that can be passed naturally. There is, however, considerable tissue injury, and the mechanisms of stone fragmentation and tissue injury are not well understood. This work investigates potential tissue damage mechanisms, with an aim towards enhancing stone fragmentation and minimizing tissue damage. Lysis of red blood cells (RBC's) due to in vitro exposure to shock waves was investigated. Fluid flow-fields induced by a non-uniform shock wave, as well as radial expansion/implosion of a bubble was hypothesized to cause cell lysis. Both the above flow-fields constitute an unsteady extensional flow, exerting inertial as well as viscous forces on the RBC membrane. The resultant membrane tension and the membrane areal strain due to the above flow-fields were estimated. Both were found to exert a significantly higher inertial force (50--100 mN/m) than the critical membrane tension (10 mN/m). Bubble-induced flow-field was estimated to last for a longer duration (˜1 microsec) compared to the shock-induced flow (˜1 ns) and hence, was predicted to be lytically more effective, in typical in vitro experimental conditions. However, in vivo conditions severely constrain bubble growth, and cell lysis due to shock-induced shear could be dominant. Hemolysis due to shock-induced shear, in absence of cavitation, was experimentally investigated. The lithotripter-generated shock wave was refocused by a parabolic reflector. This refocused wave-field had a tighter focus (smaller beam-width and a higher amplitude) than the lithotripter wave-field. Cavitation was eliminated by applying overpressure to the fluid. Acoustic emissions due to bubble activity were monitored by a novel passive cavitation detector (HP-PCD). Aluminum foils were also used to differentiate cavitational from non-cavitational mode of damage. RBC's were exposed to the reflected wave-field from

  10. Equation of state for shock compression of distended solids

    NASA Astrophysics Data System (ADS)

    Grady, Dennis; Fenton, Gregg; Vogler, Tracy

    2014-05-01

    Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additive measures of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence reveals enhancement of shock-induced phase transformation on the Hugoniot with increasing levels of initial distension for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed feature of the shock compression are incorporated into the EOS model.

  11. Equation of State for Shock Compression of High Distension Solids

    NASA Astrophysics Data System (ADS)

    Grady, Dennis

    2013-06-01

    Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additivity of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence supports acceleration of shock-induced phase transformation on the Hugoniot with increasing levels of initial distention for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed facet of the shock compression are introduced into the EOS model.

  12. Nonplanar Shock Waves in Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Mamun, A. A.; Shukla, P. K.

    2011-11-01

    Nonplanar (viz. cylindrical and spherical) electro-acoustic [dust-ion-acoustic (DIA) and dust-acoustic (DA)] shock waves have been investigated by employing the reductive perturbation method. The dust charge fluctuation (strong correlation among highly charged dust) is the source of dissipation, and is responsible for the formation of the DIA (DA) shock structures. The effects of cylindrical and spherical geometries on the time evolution of DIA and DA shock structures are examined and identified. The combined effects of vortex-like electron distribution and dust charge fluctuation (dust-correlation and effective dust-temperature) on the basic features of nonplanar DIA (DA) shock waves are pinpointed. The implications of our results in laboratory dusty plasma experiments are briefly discussed.

  13. Fluorescence anisotropy measurements under shock compression

    NASA Astrophysics Data System (ADS)

    Wang, Jue; Bassett, Will; Banishev, Alexandr; Dlott, Dana

    2015-06-01

    Fluorescence anisotropy measurements, where the parallel and perpendicular polarized emissions from probe molecules are acquired simultaneously, provide direct measurement of molecular rotational dynamics. In our experiments, the fluorescence from rhodamine 6G dye in various materials under GPa shocks produced by laser-driven flyer plates is collected, separated into two orthogonally-polarized beams using a Wollaston prism and detected with a streak camera. In liquids, the molecular rotations result from rotational diffusion and in solids from shear flow. The rotation rates can be used to determine the viscosity of the shocked medium.

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

    SciTech Connect

    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.

  15. Magnetoacoustic shock waves in dissipative degenerate plasmas

    SciTech Connect

    Hussain, S.; Mahmood, S.

    2011-11-15

    Quantum magnetoacoustic shock waves are studied in homogenous, magnetized, dissipative dense electron-ion plasma by using two fluid quantum magneto-hydrodynamic (QMHD) model. The weak dissipation effects in the system are taken into account through kinematic viscosity of the ions. The reductive perturbation method is employed to derive Korteweg-de Vries Burgers (KdVB) equation for magnetoacoustic wave propagating in the perpendicular direction to the external magnetic field in dense plasmas. The strength of magnetoacoustic shock is investigated with the variations in plasma density, magnetic field intensity, and ion kinematic viscosity of dense plasma system. The necessary condition for the existence of monotonic and oscillatory shock waves is also discussed. The numerical results are presented for illustration by using the data of astrophysical dense plasma situations such as neutron stars exist in the literature.

  16. Laser Light Scattering by Shock Waves

    NASA Technical Reports Server (NTRS)

    Panda, J.; Adamovsky, G.

    1995-01-01

    Scattering of coherent light as it propagates parallel to a shock wave, formed in front of a bluff cylindrical body placed in a supersonic stream, is studied experimentally and numerically. Two incident optical fields are considered. First, a large diameter collimated beam is allowed to pass through the shock containing flow. The light intensity distribution in the resultant shadowgraph image, measured by a low light CCD camera, shows well-defined fringes upstream and downstream of the shadow cast by the shock. In the second situation, a narrow laser beam is brought to a grazing incidence on the shock and the scattered light, which appears as a diverging sheet from the point of interaction, is visualized and measured on a screen placed normal to the laser path. Experiments are conducted on shocks formed at various free-stream Mach numbers, M, and total pressures, P(sub 0). It is found that the widths of the shock shadows in a shadowgraph image become independent of M and P(sub 0) when plotted against the jump in the refractive index, (Delta)n, created across the shock. The total scattered light measured from the narrow laser beam and shock interaction also follows the same trend. In the numerical part of the study, the shock is assumed to be a 'phase object', which introduces phase difference between the upstream and downstream propagating parts of the light disturbances. For a given shape and (Delta)n of the bow shock the phase and amplitude modulations are first calculated by ray tracing. The wave front is then propagated to the screen using the Fresnet diffraction equation. The calculated intensity distribution, for both of the incident optical fields, shows good agreement with the experimental data.

  17. Calculation of the flow field in supersonic mixed-compression inlets at angle of attack using the three-dimensional method of characteristics with discrete shock wave fitting

    NASA Technical Reports Server (NTRS)

    Vadyak, J.; Hoffman, J. D.

    1978-01-01

    The influence of molecular transport is included in the computation by treating viscous and thermal diffusion terms in the governing partial differential equations as correction terms in the method of characteristics scheme. The development of a production type computer program is reported which is capable of calculating the flow field in a variety of axisymmetric mixed-compression aircraft inlets. The results agreed well with those produced by the two-dimensional method characteristics when axisymmetric flow fields are computed. For three-dimensional flow fields, the results agree well with experimental data except in regions of high viscous interaction and boundary layer removal.

  18. Ultrafast pressure-sensitive paint for shock compression spectroscopy

    NASA Astrophysics Data System (ADS)

    Banishev, Alexandr A.; Dlott, Dana D.

    2014-05-01

    A pressure-sensitive paint (PSP) consisting of rhodamine 6G (R6G) dye in poly-methylacryate (PMMA) polymer is studied during nanosecond GPa shock compression created by km s-1 laser-launched layer plates. In contrast with conventional PSP, whose response time is limited to microseconds by diffusion of O2 in porous materials, the response time of this PSP is limited to ˜10 ns by fundamental photophysical processes. The mechanism of shock-induced PSP intensity loss is shown to be shock-enhanced intersystem crossing, which transfers some R6G population from the emissive S1 state to the dark T1 state. Simulations of dye photophysics and comparisons to experiment show that the PSP is sensitive to the complicated time-dependent density profiles produced in PMMA by different duration shocks. The risetime of the PSP response is limited by the S1 lifetime under shock compression. The fall time is limited by the T1 lifetime, which can be decreased by adding triplet quenchers. The PSP can function in two modes. When dissolved O2 (a triplet quencher) was eliminated, the fall time became relatively slow (microseconds), and the PSP sampled the peak shock pressure and held that value for a long time. When dissolved O2 was present, the intensity loss recovery became faster, so the PSP could function as a transient recorder of the shock-induced time-dependent density profile.

  19. (BARS) -- Bibliographic Retrieval System Sandia Shock Compression (SSC) database Shock Physics Index (SPHINX) database. Volume 1: UNIX version query guide customized application for INGRES

    SciTech Connect

    Herrmann, W.; von Laven, G.M.; Parker, T.

    1993-09-01

    The Bibliographic Retrieval System (BARS) is a data base management system specially designed to retrieve bibliographic references. Two databases are available, (i) the Sandia Shock Compression (SSC) database which contains over 5700 references to the literature related to stress waves in solids and their applications, and (ii) the Shock Physics Index (SPHINX) which includes over 8000 further references to stress waves in solids, material properties at intermediate and low rates, ballistic and hypervelocity impact, and explosive or shock fabrication methods. There is some overlap in the information in the two data bases.

  20. [Extracorporeal shock-wave lithotripsy for children].

    PubMed

    Wakabayashi, A; Matsuda, H; Uemura, T; Kohri, K; Kurita, T; Kanbara, N; Tamura, M

    1988-06-01

    We performed extracorporeal shock wave lithotripsy (ESWL) on a 5-year-old and 8-year-old. Ureteral calculi in both patients were disintegrated, and all fragments were passable spontaneously. The 5-year-old girl was the youngest of the cases of ESWL reported in Japan. As this patient was 107 cm in height, we put a styrofoam layer on the back of this patient. This protected her lung from the shock wave, and the height limit was released from the ESWL treatment. These cases and the peculiarities and devices for ESWL in the pediatric field are discussed. PMID:3223460

  1. Emission Lifetimes of a Fluorescent Dye under Shock Compression.

    PubMed

    Liu, Wei-long; Bassett, Will P; Christensen, James M; Dlott, Dana D

    2015-11-01

    The emission lifetimes of rhodamine 6G (R6G) were measured under shock compression to 9.1 GPa, with the dual intents of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly(methyl methacrylate) (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and the emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0 to 9 GPa, with a slope of -0.22 ns·GPa(-1). The linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, because lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure.

  2. Emission Lifetimes of a Fluorescent Dye under Shock Compression.

    PubMed

    Liu, Wei-long; Bassett, Will P; Christensen, James M; Dlott, Dana D

    2015-11-01

    The emission lifetimes of rhodamine 6G (R6G) were measured under shock compression to 9.1 GPa, with the dual intents of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly(methyl methacrylate) (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and the emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0 to 9 GPa, with a slope of -0.22 ns·GPa(-1). The linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, because lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure. PMID:26469397

  3. Molecular Dynamics of Shock Wave Interaction with Nanoscale Structured Materials

    NASA Astrophysics Data System (ADS)

    Al-Qananwah, Ahmad K.

    Typical theoretical treatments of shock wave interactions are based on a continuum approach, which cannot resolve the spatial variations in solids with nano-scale porous structure. Nano-structured materials have the potential to attenuate the strength of traveling shock waves because of their high surface-to-volume ratio. To investigate such interactions we have developed a molecular dynamics simulation model, based on Short Range Attractive interactions. A piston, modeled as a uni-directional repulsive force field translating at a prescribed velocity, impinges on a region of gas which is compressed to form a shock, which in turn is driven against an atomistic solid wall. Periodic boundary conditions are used in the directions orthogonal to the piston motion, and we have considered solids based on either embedded atom potentials (target structure) or tethered potential (rigid piston, holding wall). Velocity, temperature and stress fields are computed locally in both gas and solid regions, and displacements within the solid are interpreted in terms of its elastic constants. In this work we present results of the elastic behavior of solid structures subjected to shock wave impact and analysis of energy transport and absorption in porous materials. The results indicated that the presence of nano-porous material layers in front of a target wall reduced the stress magnitude detected inside and the energy deposited there by about 30 percent while, at the same time, its loading rate was decreased substantially.

  4. High-energy synchrotron X-ray radiography of shock-compressed materials

    NASA Astrophysics Data System (ADS)

    Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

    2015-06-01

    This presentation will discuss the development and application of a high-energy (50 to 250 keV) synchrotron X-ray imaging method to study shock-compressed, high-Z samples at Beamline I12 at the Diamond Light Source synchrotron (Rutherford-Appleton Laboratory, UK). Shock waves are driven into materials using a portable, single-stage gas gun designed by the Institute of Shock Physics. Following plate impact, material deformation is probed in-situ by white-beam X-ray radiography and complimentary velocimetry diagnostics. The high energies, large beam size (13 x 13 mm), and appreciable sample volumes (~ 1 cm3) viable for study at Beamline I12 compliment existing in-house pulsed X-ray capabilities and studies at the Dynamic Compression Sector. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

  5. Multiwavelength optical pyrometer for shock compression experiments.

    PubMed

    Lyzenga, G A; Ahrens, T J

    1979-11-01

    A system for measurement of the spectral radiance of materials shocked to high pressures ( approximately 100 GPa) by impact using a light gas gun is described. Thermal radiation from the sample is sampled at six wavelength bands in the visible spectrum, and each signal is separately detected by solid-state photodiodes, and recorded with a time resolution of approximately 10 ns. Interpretation of the records in terms of temperature of transparent sample materials is discussed. Results of a series of exploratory experiments with metals are also given. Shock temperatures in the range 4000-8000 K have been reliably measured. Spectral radiance and temperatures have been determined with uncertainties of 2%. PMID:18699402

  6. Weakly nonlinear dust ion-acoustic shock waves in a dusty plasma with nonthermal electrons

    SciTech Connect

    Berbri, Abderrezak; Tribeche, Mouloud

    2009-05-15

    Weakly nonlinear dust ion-acoustic (DIA) shock waves are investigated in a dusty plasma with nonthermal electrons. A modified Korteweg-de Vries equation with a cubic nonlinearity is derived. Due to the net negative dust charge {mu}Z{sub d} and electron nonthermality, the present plasma model can admit compressive and rarefactive weak DIA shock waves. The effect of increasing {mu}Z{sub d} is to lower the critical nonthermal parameter {beta}{sub c} above which only rarefactive DIA shock waves are admitted. Our investigation may help to understand the nonlinear structures observed in the auroral acceleration regions.

  7. Plasma waves downstream of weak collisionless shocks

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.; Greenstadt, E. W.; Moses, S. L.; Smith, E. J.; Tsurutani, B. T.

    1993-01-01

    In September 1983 the International Sun Earth Explorer 3 (ISEE 3) International Cometary Explorer (ICE) spacecraft made a long traversal of the distant dawnside flank region of the Earth's magnetosphere and had many encounters with the low Mach number bow shock. These weak shocks excite plasma wave electric field turbulence with amplitudes comparable to those detected in the much stronger bow shock near the nose region. Downstream of quasi-perpendicular (quasi-parallel) shocks, the E field spectra exhibit a strong peak (plateau) at midfrequencies (1 - 3 kHz); the plateau shape is produced by a low-frequency (100 - 300 Hz) emission which is more intense behind downstream of two quasi-perpendicular shocks show that the low frequency signals are polarized parallel to the magnetic field, whereas the midfrequency emissions are unpolarized or only weakly polarized. A new high frequency (10 - 30 kHz) emission which is above the maximum Doppler shift exhibit a distinct peak at high frequencies; this peak is often blurred by the large amplitude fluctuations of the midfrequency waves. The high-frequency component is strongly polarized along the magnetic field and varies independently of the lower-frequency waves.

  8. Amorphization and nanocrystallization of silcon under shock compression

    SciTech Connect

    Remington, B. A.; Wehrenberg, C. E.; Zhao, S.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2015-11-06

    High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energy changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. As a result, the nucleation of amorphization is analyzed qualitatively by classical nucleation theory.

  9. Frequency shift measurement in shock-compressed materials

    DOEpatents

    Moore, David S.; Schmidt, Stephen C.

    1985-01-01

    A method for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the shock front advancing through the sample, thereby minimizing adverse effects of refraction.

  10. Determination of dynamic shear strength of 2024 aluminum alloy under shock compression

    NASA Astrophysics Data System (ADS)

    Zhang, H. S.; Yan, M.; Wang, H. Y.; Shen, L. T.; Dai, L. H.

    2016-04-01

    A series of plate impact shock-reshock and shock-release experiments were conducted by using an one-stage light gas gun to determine the critical shear strength of the 2024 aluminum alloy under shock compression levels ranging from 0.66 to 3.05 GPa in the present study. In the experiments, a dual flyer plate assembly, i.e., the 2024 aluminum alloy flyer backed either by a brass plate or a PMMA plate, was utilized to produce reshock or release wave. The stress profiles of uniaxial plane strain wave propagation in the 2024 aluminum alloy sample under different pre-compressed states were measured by the embedded stress gauges. The stress-strain data at corresponding states were then calculated by a Lagrangian analysis method named as path line method. The critical shear strengths at different stress levels were finally obtained by self-consistent method. The results show that, at the low shock compression level (0.66 to 3.05 GPa), the critical shear strength of the 2024 aluminum alloy cannot be ignored and increases with the increasing longitudinal stress, which may be attributed to rate-dependence and/or pressure dependent yield behavior of the 2024 aluminum alloy.

  11. Chromospheric heating by acoustic shock waves

    NASA Technical Reports Server (NTRS)

    Jordan, Stuart D.

    1993-01-01

    Work by Anderson & Athay (1989) suggests that the mechanical energy required to heat the quiet solar chromosphere might be due to the dissipation of weak acoustic shocks. The calculations reported here demonstrate that a simple picture of chromospheric shock heating by acoustic waves propagating upward through a model solar atmosphere, free of both magnetic fields and local inhomogeneities, cannot reproduce their chromospheric model. The primary reason is the tendency for vertically propagating acoustic waves in the range of allowed periods to dissipate too low in the atmosphere, providing insufficient residual energy for the middle chromosphere. The effect of diverging magnetic fields and the corresponding expanding acoustic wavefronts on the mechanical dissipation length is then discussed as a means of preserving a quasi-acoustic heating hypothesis. It is argued that this effect, in a canopy that overlies the low chromosphere, might preserve the acoustic shock hypothesis consistent with the chromospheric radiation losses computed by Anderson & Athay.

  12. Stimulated Raman scattering from ice-VIII by shock-induced compression in liquid water

    NASA Astrophysics Data System (ADS)

    Men, Zhiwei; Li, Zuowei; Zhou, Mi; Lu, Guohui; Zou, Bo; Li, Zhanlong; Sun, Chenglin

    2012-03-01

    Stimulated Raman scattering (SRS) from ice-VIII was investigated using shock-induced compression (SIC) generated by laser-induced breakdown in liquid water. Three backward SRS peaks of OH stretching vibrations and one backward SRS characteristic peak of lattice translation were observed. The SRS spectra indicated that the ice-VIII structure is formed by SIC, as the trajectory of the SIC passes through the stable pressure-temperature range of ice-VIII. The static electric field generated by electron jets protects proton-ordered structure. The laser-induced shock wave mechanism is also discussed.

  13. Shock Wave Dynamics in Weakly Ionized Gases

    NASA Technical Reports Server (NTRS)

    Johnson, Joseph A., III

    1998-01-01

    We have begun a comprehensive series of analyses and experiments to study the basic problem of shock wave dynamics in ionized media. Our objective is to isolate the mechanisms that are responsible for the decrease in the shock amplitude and also to determine the relevant plasma parameters that will be required for a drag reduction scheme in an actual high altitude hypersonic flight. Specifically, we have initiated a program of analyses and measurements with the objective of (i) fully characterizing the propagation dynamics in plasmas formed in gases of aerodynamic interest, (ii) isolating the mechanisms responsible for the decreased shock strength and increased shock velocity, (iii) extrapolating the laboratory observations to the technology of supersonic flight.

  14. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney... Notifications (510(k)'s) for Extracorporeal Shock Wave Lithotripters Indicated for the Fragmentation of...

  15. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney... Notifications (510(k)'s) for Extracorporeal Shock Wave Lithotripters Indicated for the Fragmentation of...

  16. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... focuses ultrasonic shock waves into the body to noninvasively fragment urinary calculi within the kidney... Notifications (510(k)'s) for Extracorporeal Shock Wave Lithotripters Indicated for the Fragmentation of...

  17. Shock wave absorber having a deformable liner

    DOEpatents

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

    1983-08-26

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

  18. Reactive, anomalous compression in shocked polyurethane foams

    NASA Astrophysics Data System (ADS)

    Dattelbaum, Dana M.; Coe, Joshua D.; Kiyanda, Charles B.; Gustavsen, Richard L.; Patterson, Brian M.

    2014-05-01

    We present the results of plate impact experiments performed on 30%-75% porous, polymeric methylene diphenyl diisocyanate polyurethane foams. The combination of new data with those previously obtained on full-density material was used to calibrate complete equations-of-state under both inert and chemically reactive frameworks. Description of unreacted polyurethane was based on a combination of Hayes and P-α models, whereas its decomposition products were predicted via free energy minimization under the assumption of chemical and thermodynamic equilibrium. Correspondence of experiment and theory suggests that polyurethane at all densities decomposes when shocked above some threshold pressure, and that this threshold falls dramatically as a function of initial porosity. The shock locus of foams at 50% or less of theoretical maximum density was found "anomalous" in the sense that final volumes increased with pressure. We attribute this anomaly to chemical decomposition of the initial matrix to a mixture of small-molecule fluids and bulk carbon (graphite or diamond, depending on the initial density).

  19. Reactive, anomalous compression in shocked polyurethane foams

    SciTech Connect

    Dattelbaum, Dana M. Gustavsen, Richard L.; Coe, Joshua D. Kiyanda, Charles B.; Patterson, Brian M.

    2014-05-07

    We present the results of plate impact experiments performed on 30%–75% porous, polymeric methylene diphenyl diisocyanate polyurethane foams. The combination of new data with those previously obtained on full-density material was used to calibrate complete equations-of-state under both inert and chemically reactive frameworks. Description of unreacted polyurethane was based on a combination of Hayes and P-α models, whereas its decomposition products were predicted via free energy minimization under the assumption of chemical and thermodynamic equilibrium. Correspondence of experiment and theory suggests that polyurethane at all densities decomposes when shocked above some threshold pressure, and that this threshold falls dramatically as a function of initial porosity. The shock locus of foams at 50% or less of theoretical maximum density was found “anomalous” in the sense that final volumes increased with pressure. We attribute this anomaly to chemical decomposition of the initial matrix to a mixture of small-molecule fluids and bulk carbon (graphite or diamond, depending on the initial density)

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

    NASA Technical Reports Server (NTRS)

    Kazeminezhad, F.; Anghai, S.

    2008-01-01

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

  1. Interferometric data for a shock-wave/boundary-layer interaction

    NASA Technical Reports Server (NTRS)

    Dunagan, Stephen E.; Brown, James L.; Miles, John B.

    1986-01-01

    An experimental study of the axisymmetric shock-wave / boundary-layer strong interaction flow generated in the vicinity of a cylinder-cone intersection was conducted. The study data are useful in the documentation and understanding of compressible turbulent strong interaction flows, and are part of a more general effort to improve turbulence modeling for compressible two- and three-dimensional strong viscous/inviscid interactions. The nominal free stream Mach number was 2.85. Tunnel total pressures of 1.7 and 3.4 atm provided Reynolds number values of 18 x 10(6) and 36 x 10(6) based on model length. Three cone angles were studied giving negligible, incipient, and large scale flow separation. The initial cylinder boundary layer upstream of the interaction had a thickness of 1.0 cm. The subsonic layer of the cylinder boundary layer was quite thin, and in all cases, the shock wave penetrated a significant portion of the boundary layer. Owing to the thickness of the cylinder boundary layer, considerable structural detail was resolved for the three shock-wave / boundary-layer interaction cases considered. The primary emphasis was on the application of the holographic interferometry technique. The density field was deduced from an interferometric analysis based on the Able transform. Supporting data were obtained using a 2-D laser velocimeter, as well as mean wall pressure and oil flow measurements. The attached flow case was observed to be steady, while the separated cases exhibited shock unsteadiness. Comparisons with Navier-Stokes computations using a two-equation turbulence model are presented.

  2. Finite element modelling of radial shock wave therapy for chronic plantar fasciitis.

    PubMed

    Alkhamaali, Zaied K; Crocombe, Andrew D; Solan, Matthew C; Cirovic, Srdjan

    2016-01-01

    Therapeutic use of high-amplitude pressure waves, or shock wave therapy (SWT), is emerging as a popular method for treating musculoskeletal disorders. However, the mechanism(s) through which this technique promotes healing are unclear. Finite element models of a shock wave source and the foot were constructed to gain a better understanding of the mechanical stimuli that SWT produces in the context of plantar fasciitis treatment. The model of the shock wave source was based on the geometry of an actual radial shock wave device, in which pressure waves are generated through the collision of two metallic objects: a projectile and an applicator. The foot model was based on the geometry reconstructed from magnetic resonance images of a volunteer and it comprised bones, cartilage, soft tissue, plantar fascia, and Achilles tendon. Dynamic simulations were conducted of a single and of two successive shock wave pulses administered to the foot. The collision between the projectile and the applicator resulted in a stress wave in the applicator. This wave was transmitted into the soft tissue in the form of compression-rarefaction pressure waves with an amplitude of the order of several MPa. The negative pressure at the plantar fascia reached values of over 1.5 MPa, which could be sufficient to generate cavitation in the tissue. The results also show that multiple shock wave pulses may have a cumulative effect in terms of strain energy accumulation in the foot. PMID:26465270

  3. Finite element modelling of radial shock wave therapy for chronic plantar fasciitis.

    PubMed

    Alkhamaali, Zaied K; Crocombe, Andrew D; Solan, Matthew C; Cirovic, Srdjan

    2016-01-01

    Therapeutic use of high-amplitude pressure waves, or shock wave therapy (SWT), is emerging as a popular method for treating musculoskeletal disorders. However, the mechanism(s) through which this technique promotes healing are unclear. Finite element models of a shock wave source and the foot were constructed to gain a better understanding of the mechanical stimuli that SWT produces in the context of plantar fasciitis treatment. The model of the shock wave source was based on the geometry of an actual radial shock wave device, in which pressure waves are generated through the collision of two metallic objects: a projectile and an applicator. The foot model was based on the geometry reconstructed from magnetic resonance images of a volunteer and it comprised bones, cartilage, soft tissue, plantar fascia, and Achilles tendon. Dynamic simulations were conducted of a single and of two successive shock wave pulses administered to the foot. The collision between the projectile and the applicator resulted in a stress wave in the applicator. This wave was transmitted into the soft tissue in the form of compression-rarefaction pressure waves with an amplitude of the order of several MPa. The negative pressure at the plantar fascia reached values of over 1.5 MPa, which could be sufficient to generate cavitation in the tissue. The results also show that multiple shock wave pulses may have a cumulative effect in terms of strain energy accumulation in the foot.

  4. Shock wave structure in heterogeneous reactive media

    SciTech Connect

    Baer, M.R.

    1997-06-01

    Continuum mixture theory and mesoscale modeling are applied to describe the behavior of shock-loaded heterogeneous media. One-dimensional simulations of gas-gun experiments demonstrate that the wave features are well described by mixture theory, including reflected wave behavior and conditions where significant reaction is initiated. Detailed wave fields are resolved in numerical simulations of impact on a lattice of discrete explosive {open_quotes}crystals{close_quotes}. It is shown that rapid distortion first occurs at material contact points; the nature of the dispersive fields includes large amplitude fluctuations of stress over several particle pathlengths. Localization of energy causes {open_quotes}hot-spots{close_quotes} due to shock focusing and plastic work as material flows into interstitial regions.

  5. Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL.

    PubMed

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G; Beckwith, Martha A; Collins, Gilbert W; Higginbotham, Andrew; Wark, Justin S; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B; Schroer, Christian G

    2015-01-01

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

  6. Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL

    NASA Astrophysics Data System (ADS)

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-06-01

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

  7. Imaging Shock Waves in Diamond with Both High Temporal and Spatial Resolution at an XFEL

    PubMed Central

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-01-01

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions. PMID:26086176

  8. Imaging shock waves in diamond with both high temporal and spatial resolution at an XFEL

    SciTech Connect

    Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; Wark, Justin S.; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Schroer, Christian G.

    2015-06-18

    The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic compression wave in diamond. The elastic wave was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnified x-ray phase-contrast imaging. The temporal evolution of the shock wave can be monitored, yielding detailed information on shock dynamics, such as the shock velocity, the shock front width, and the local compression of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.

  9. Application Of Holographic Interferometry To Shock Wave Research

    NASA Astrophysics Data System (ADS)

    Takayama, K.

    1983-10-01

    Paper reports a successful application of holographic interferometry to the shock wave research. Four topics are discussed; i) transonic flow over an aerofoil, ii) shock wave propagation and diffraction past a circular cross-sectional 90° bend and two-dimensional straight or curved wedges, iii) stability of converging cylindrical shock waves and iv) propagation and focusing of underwater shock waves. Experiments were conducted on shock tubes equipped with a double exposure holographic interferometer. In each case isopycnics around shock waves were determined and three-dimensional shock wave interactions were also observed. Results are not only bringing forth new interesting findings to the shock wave research but also showing a further potentiality of holographic interferometry to the high speed gasdynamic study.

  10. Shock-driven chemistry and reactive wave dynamics in benzene

    NASA Astrophysics Data System (ADS)

    Sheffield, Stephen; Dattelbaum, Dana; Coe, Joshua; Los Alamos National Laboratory Team

    2015-06-01

    Benzene is a stable organic chemistry molecule because of its electronic structure - aromatic stability is derived from its delocalized, π-bonded, 6-membered planar ring structure. Benzene principal shock Hugoniot states have been reported previously by several groups, at both high and low pressures. Cusps (or discontinuities) in the shock Hugoniot provide evidence that chemical reactions take place under shockwave compression of benzene at input pressure conditions above 12 GPa. In other shock-driven experiments, spectral changes have been observed near this cusp condition, indicating that the cusp is associated with shock-driven chemical reaction(s). In this work, a series of gas-gun-driven plate impact experiments were performed to measure and quantify the details associated with shock-driven reactive flow in benzene. Using embedded electromagnetic gauges (with up to 10 Lagrangian gauge positions in-material in a single experiment) multiple, evolving wave structures have been measured in benzene when the inputs were above 12 GPa, with the details changing as the input pressure was increased. Detailed insights into the volume changes associated with the chemical reaction(s), reaction rates, and estimates of the bulk moduli of reaction intermediates and products were obtained. Using this new experimental data (along with the older experimental data from others), the benzene reactant and product Hugoniot loci have been modeled by thermodynamically complete equations of state.

  11. A note on weak shock wave reflection

    NASA Astrophysics Data System (ADS)

    Viero, D. P.; Susin, F. M.; Defina, A.

    2013-09-01

    This work discusses the possibility of reconstructing, both numerically and experimentally, the steady state flow field and shock reflection pattern close to the triple point of von Neumann, Guderley and Vasilev reflections. First, a criterion for the orientation of shock wave fronts, even in the case of subcritical/subsonic flow downstream the front, is introduced and formalized. Then, a technique for obtaining a close view of the above reflection patterns centered about the triple point is described and a numerical example, within the framework of shallow water flow, is presented and discussed.

  12. Shock wave interactions between slender bodies - Some aspects of three-dimensional shock wave diffraction

    NASA Astrophysics Data System (ADS)

    Hooseria, S. J.; Skews, B. W.

    2016-04-01

    A complex interference flowfield consisting of multiple shocks and expansion waves is produced when high-speed slender bodies are placed in close proximity. The disturbances originating from a generator body impinge onto the adjacent receiver body, modifying the local flow conditions over the receiver. This paper aims to uncover the basic gas dynamics produced by two closely spaced slender bodies in a supersonic freestream. Experiments and numerical simulations were used to interpret the flowfield, where good agreement between the predictions and measurements was observed. The numerical data were then used to characterise the attenuation associated with shock wave diffraction, which was found to be interdependent with the bow shock contact perimeter over the receiver bodies. Shock-induced boundary layer separation was observed over the conical and hemispherical receiver bodies. These strong viscous-shock interactions result in double-reflected, as well as double-diffracted shock wave geometries in the interference region, and the diffracting waves progress over the conical and hemispherical receivers' surfaces in "lambda" type configurations. This gives evidence that viscous effects can have a substantial influence on the local bow shock structure surrounding high-speed slender bodies in close proximity.

  13. Solitary and shock waves in discrete strongly nonlinear double power-law materials

    NASA Astrophysics Data System (ADS)

    Herbold, E. B.; Nesterenko, V. F.

    2007-06-01

    A laminar metamaterial supporting strongly nonlinear solitary and shock waves with impact energy mitigating capabilities is presented. It consists of steel plates with intermittent polymer toroidal rings acting as strongly nonlinear springs with large allowable strain. The force-displacement relationship of a compressed o-ring is described by the addition of two power-law relationships resulting in a solitary wave speed and width depending on the amplitude. This double nonlinearity allows splitting of an initial impulse into three separate strongly nonlinear solitary wave trains. Solitary and shock waves are observed experimentally and analyzed numerically in an assembly with Teflon o-rings.

  14. Plasmons in strongly coupled shock-compressed matter

    SciTech Connect

    Neumayer, P; Fortmann, C; Doppner, T; Davis, P; Falcone, R W; Kritcher, A L; Landen, O L; Lee, H J; Lee, R W; Niemann, C; Pape, S L; Glenzer, S H

    2010-04-15

    We present the first measurements of the plasmon dispersion and damping in laser shock-compressed solid matter. Petawatt laser produced K-{alpha} radiation scatters on boron targets compressed by a 10 ns-long 400 J laser pulse. In the vicinity of the Fermi momentum, the scattering spectra show dispersionless, collisionally damped plasmons, indicating a strongly coupled electron liquid. These observations agree with x-ray scattering calculations that include both the Born-Mermin approximation to account for electron-ion collisional damping and local field corrections reflecting electron-electron correlations.

  15. Application of sound-absorbent plastic to weak-shock-wave attenuators

    NASA Astrophysics Data System (ADS)

    Ootsuta, Katsuhisa; Matsuoka, Kei; Sasoh, Akihiro; Takayama, Kazuyoshi

    1998-04-01

    A device for attenuating weak shock waves propagating in a duct has been developed utilizing sound-absorbent plastic which is usually used for attenuating sound waves. The device has a tube made of the sound-absorbent plastic installed coaxially to a surrounding metal tube with a clearance between them. The clearance acts as an air layer to enhance the performance of the shock wave attenuation. When a weak shock wave propagates through this device, the pressure gradient of the shock wave is gradually smeared and hence its overpressure is decreased. The performance of the device was examined using a 1/250-scaled train tunnel simulator which simulated the discharge of weak shock waves created by high-speed entry of trains to tunnels. The overpressure of the shock waves ranged up to 5 kPa. The shock wave overpressure was decreased by 90% with the present attenuator attached. This device can be applied to various industrial noise suppressions which are associated with unsteady compressible flows.

  16. Experimental Investigation of Passive Shock Wave Mitigation using Obstacle Arrangements

    NASA Astrophysics Data System (ADS)

    Nguyen, Monica; Wan, Qian; Eliasson, Veronica

    2014-11-01

    With its vast range in applications, especially in the defense industry, shock wave mitigation is an ongoing research area of interest to the shock dynamics community. Passive shock wave mitigation methods range from forcing the shock wave to abruptly change its direction to introducing barriers or obstacles of various shapes and materials in the path of the shock wave. Obstacles provide attenuation through complicated shock wave interactions and reflections. In this work, we have performed shock tube experiments to investigate shock wave mitigation due to solid obstacles placed along the curve of a logarithmic spiral. Different shapes (cylindrical and square) of obstacles with different materials (solid and foam) have been used. High-speed schlieren optics and background-oriented schlieren techniques have been used together with pressure measurements to quantify the effects of mitigation. Results have also been compared to numerical simulations and show good agreement.

  17. Frequency shift measurement in shock-compressed materials

    DOEpatents

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

    1984-02-21

    A method is disclosed for determining molecular vibrational frequencies in shock-compressed transparent materials. A single laser beam pulse is directed into a sample material while the material is shock-compressed from a direction opposite that of the incident laser beam. A Stokes beam produced by stimulated Raman scattering is emitted back along the path of the incident laser beam, that is, in the opposite direction to that of the incident laser beam. The Stokes beam is separated from the incident beam and its frequency measured. The difference in frequency between the Stokes beam and the incident beam is representative of the characteristic frequency of the Raman active mode of the sample. Both the incident beam and the Stokes beam pass perpendicularly through the stock front advancing through the sample, thereby minimizing adverse effects of refraction.

  18. Enhanced densification under shock compression in porous silicon

    SciTech Connect

    Lane, J. Matthew; Thompson, Aidan Patrick; Vogler, Tracy

    2014-10-27

    Under shock compression, most porous materials exhibit lower densities for a given pressure than that of a full-dense sample of the same material. However, some porous materials exhibit an anomalous, or enhanced, densification under shock compression. The mechanism driving this behavior was not completely determined. We present evidence from atomistic simulation that pure silicon belongs to this anomalous class of materials and demonstrate the associated mechanisms responsible for the effect in porous silicon. Atomistic response indicates that local shear strain in the neighborhood of collapsing pores catalyzes a local solid-solid phase transformation even when bulk pressures are below the thermodynamic phase transformation pressure. This metastable, local, and partial, solid-solid phase transformation, which accounts for the enhanced densification in silicon, is driven by the local stress state near the void, not equilibrium thermodynamics. This mechanism may also explain the phenomenon in other covalently bonded materials.

  19. Enhanced densification under shock compression in porous silicon

    DOE PAGES

    Lane, J. Matthew; Thompson, Aidan Patrick; Vogler, Tracy

    2014-10-27

    Under shock compression, most porous materials exhibit lower densities for a given pressure than that of a full-dense sample of the same material. However, some porous materials exhibit an anomalous, or enhanced, densification under shock compression. The mechanism driving this behavior was not completely determined. We present evidence from atomistic simulation that pure silicon belongs to this anomalous class of materials and demonstrate the associated mechanisms responsible for the effect in porous silicon. Atomistic response indicates that local shear strain in the neighborhood of collapsing pores catalyzes a local solid-solid phase transformation even when bulk pressures are below the thermodynamicmore » phase transformation pressure. This metastable, local, and partial, solid-solid phase transformation, which accounts for the enhanced densification in silicon, is driven by the local stress state near the void, not equilibrium thermodynamics. This mechanism may also explain the phenomenon in other covalently bonded materials.« less

  20. Shock Experiments on Pre-Compressed Fluid Helium

    SciTech Connect

    Eggert, J. H.; Celliers, P. M.; Hicks, D. G.; Rygg, J. R.; Collins, G. W.; Brygoo, S.; Loubeyre, P.; McWilliams, R. S.; Spaulding, D.; Jeanloz, R.; Boehly, T. R.

    2009-09-10

    We summarize current methods and results for coupling laser-induced shocks into pre-compressed Helium contained in a diamond anvil cell (DAC). We are able to load helium, hydrogen, deuterium, and helium-hydrogen mixtures into a DAC and propagate a laser-generated shock into the pre-compressed sample. This technique has allowed us to measure the Hugoniot for helium at initial densities ranging from 1 to 3.5 times liquid density. We have developed and used a methodology whereby all of our measurements are referenced to crystalline quartz, which allows us to update our results as the properties of quartz are refined in the future. We also report the identification and elimination of severe electro-magnetic pulses (EMP) associated with plasma stagnation associated with ablation in a DAC.

  1. Kinetic Alfvén Waves in the Inner Magnetosphere Triggered by an Interplanetary Shock

    NASA Astrophysics Data System (ADS)

    Malaspina, D.; Claudepierre, S. G.; Takahashi, K.; Jaynes, A. N.; Elkington, S. R.; Ergun, R.; Wygant, J. R.; Reeves, G. D.; Kletzing, C.

    2015-12-01

    An interplanetary shock impacted Earth's magnetic field on October 2, 2013, compressing the magnetosphere and triggering a global 3.5 mHz oscillation. This large-amplitude ULF (ultra low frequency) wave was observed in-situ, using both magnetic and electric field data, by the Van Allen Probe B spacecraft. At the same time, Van Allen Probe B observed higher frequency broadband wave power in conjunction with, and modulated by, this ULF wave. A detailed analysis reveals that these broadband waves are kinetic Alfvén waves, possibly generated by large-scale Alfvénic fluctuations coupling to smaller scales. This event suggests that magnetospheric compression by interplanetary shocks can induce abrupt generation of kinetic Alfvén waves over large portions of the inner magnetosphere, potentially resulting in prompt ion heating throughout the inner magnetosphere.

  2. X-ray scattering measurements of laser-driven shock compressed plastic and deuterated plastic targets

    NASA Astrophysics Data System (ADS)

    Gauthier, Maxence; Fletcher, Luke; Ravasio, Alessandra; Döppner, Tilo; Glenzer, Siegfried; HED science Collaboration

    2015-03-01

    The study of materials under extreme conditions, i.e., high energy density, has gathered enormous scientific interest in various domains from inertial confinement fusion to planetary physics. The material response of plastic to shock and its behavior is important because of its common use as an ablator in inertial confinement fusion experiments. In this study, simultaneous measurements of spectrally and wavenumber resolved x-ray scattering emission from laser-shock compressed plastic foils allow us to study the structural transition from a polymer to a liquid-like state. The 527 nm, 2 GW laser system available at the MEC station of the LCLS facility has been used to compress CH and CD foils using laser-driven shocks. 40 to 57 μm thick CH and CD targets were compressed using 3 ns square pulses with total laser energy of 6 J per beam. A drive intensity of 3x1013 W/cm2 on each irradiated surface was used to generate high-pressure shock waves into the sample, while 8 keV x-rays from LCLS was used to probe the target.

  3. Development of a broadband reflectivity diagnostic for laser driven shock compression experiments.

    PubMed

    Ali, S J; Bolme, C A; Collins, G W; Jeanloz, R

    2015-04-01

    A normal-incidence visible and near-infrared shock wave optical reflectivity diagnostic was constructed to investigate changes in the optical properties of materials under dynamic laser compression. Documenting wavelength- and time-dependent changes in the optical properties of laser-shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved, but we succeeded in doing so by broadening a series of time delayed 800-nm pulses from an ultrafast Ti:sapphire laser to generate high-intensity broadband light at nanosecond time scales. This diagnostic was demonstrated over the wavelength range 450-1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off-normal incidence velocity interferometry (velocity interferometer system for any reflector) characterized the sample under laser-compression and also provided an independent reflectivity measurement at 532 nm wavelength. The shock-driven semiconductor-to-metallic transition in germanium was documented by the way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm.

  4. The equation of state of dense xenon plasma under double-shock compression to 172 GPA

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Gu, Yunjun; Chen, Qifeng; Chen, Zhiyun

    2012-03-01

    Warm dense plasmas having uniform, constant density, and temperature were generated by passage of planar shock wave through gas. The pressure of the Xe plasma was accurately measured by optical radiation method in the range of 172 GPa. The shock was produced using the flyer plate impact by accelerated up to ~6 km/s with a two-stage light gas gun. The time-resolved optical radiation histories were acquired by using a multi-wavelength channel optical transience radiance pyrometer. Shock velocity was measured and particle velocity was determined by the impedance-matching methods. Experimental data available of the Xe specimen in this region were compared with the calculations by the self-consistent fluid variational theory (SFVT). The observed shock compression ratios range from ρ/ρ0 = 3.7 for the initial density of 2.2 g/cm3 to ρ/ρ0 = 8.5 for the initial density of 0.04 g/cm3. The comparison of the Hugoniot in the Pressure-compression plane clearly shows how higher initial densities result in lower final compression.

  5. Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

    DOEpatents

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

    1983-12-16

    A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

  6. Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

    DOEpatents

    Moore, David S.; Schmidt, Stephen C.

    1985-01-01

    A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

  7. Development of a broadband reflectivity diagnostic for laser driven shock compression experiments

    SciTech Connect

    Ali, S. J.; Bolme, C. A.; Collins, G. W.; Jeanloz, R.

    2015-04-01

    A normal - incidence visible and near - infrared Shock Wave Optical Reflectivity Diagnostic (SWORD) was constructed to investigate changes in the optical properties of materials under dynamic laser compression . Documenting wavelength - and time - dependent changes in the optical properties of laser - shock compressed samples has been difficult, primarily due to the small sample sizes and short time scales involved , but we succeeded in doing so by broadening a series of time delayed 800 - nm pulses from an ultra fast Ti: sapphire laser to generate high - intensity broadband light at nanosecond time scales . This diagnostic was demonstrated over the wavelength range 450 to 1150 nm with up to 16 time displaced spectra during a single shock experiment. Simultaneous off - normal incidence velocity interferometry (VISAR) characterize d the sample under laser - compression , and also provide d a n independent reflectivity measurement at 532 nm wavelength . Lastly, the shock - driven semiconductor - to - metallic transition in germanium was documented by way of reflectivity measurements with 0.5 ns time resolution and a wavelength resolution of 10 nm .

  8. Holographic flow visualization of time-varying shock waves

    NASA Technical Reports Server (NTRS)

    Decker, A. J.

    1981-01-01

    Rapid-double-exposure, diffuse-illumination holography is evaluated analytically and experimentally as a flow visualization method for time-varying shock waves. Conditions are determined that minimize the distance (localization error) between the surface or curve of interference-fringe localization and the shock surface. Treated specifically are the cases of shock waves in a transonic compressor rotor for which there is laser anemometer data for comparison and shock waves in a flutter cascade.

  9. Stability of spherical converging shock wave

    NASA Astrophysics Data System (ADS)

    Murakami, M.; Sanz, J.; Iwamoto, Y.

    2015-07-01

    Based on Guderley's self-similar solution, stability of spherical converging shock wave is studied. A rigorous linear perturbation theory is developed, in which the growth rate of perturbation is given as a function of the spherical harmonic number ℓ and the specific heats ratio γ. Numerical calculation reveals the existence of a γ-dependent cut-off mode number ℓc, such that all the eigenmode perturbations for ℓ > ℓc are smeared out as the shock wave converges at the center. The analysis is applied to partially spherical geometries to give significant implication for different ignition schemes of inertial confinement fusion. Two-dimensional hydrodynamic simulations are performed to verify the theory.

  10. Stability of spherical converging shock wave

    SciTech Connect

    Murakami, M.; Sanz, J.; Iwamoto, Y.

    2015-07-15

    Based on Guderley's self-similar solution, stability of spherical converging shock wave is studied. A rigorous linear perturbation theory is developed, in which the growth rate of perturbation is given as a function of the spherical harmonic number ℓ and the specific heats ratio γ. Numerical calculation reveals the existence of a γ-dependent cut-off mode number ℓ{sub c}, such that all the eigenmode perturbations for ℓ > ℓ{sub c} are smeared out as the shock wave converges at the center. The analysis is applied to partially spherical geometries to give significant implication for different ignition schemes of inertial confinement fusion. Two-dimensional hydrodynamic simulations are performed to verify the theory.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    SciTech Connect

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

    2006-08-15

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

  13. Extra-corporeal shock wave lithotripsy.

    PubMed Central

    Pemberton, J.

    1987-01-01

    Extra-corporeal shock wave lithotripsy (ESWL) has proved to be a revolutionary advance in the treatment of renal stone disease. It, itself, is non-invasive but may necessitate or be used as an adjunct to more invasive auxiliary procedures. The basic principles of lithotripsy, the clinical experience thus far and probable future applications are discussed. Images Figure 2 Figure 4 Figure 5 Figure 7 Figure 8 PMID:3330235

  14. Advances in ferroelectric polymers for shock compression sensors

    SciTech Connect

    Bauer, F.; Moulard, H.; Samara, G.

    1998-07-01

    Our studies of the shock compression response of PVDF polymer are continuing in order to understand the physical properties under shock loading and to develop high fidelity, reproducible, time-resolved dynamic stress gauges. New PVDF technology, new electrode configurations and piezoelectric analysis have resulted in enhanced precision gauges. Our new standard gauges have a precision of better than 1{percent} in electrical charge release under shock up to 15 GPa. The piezoelectric response of shock compressed PVDF gauges 1 mm{sup 2} in active area has been studied and yielded well-behaved reproducible data up to 20 GPa. Analysis of the response of these gauges in the {open_quotes}thin mode regime{close_quotes} using a Lagrangian hydrocode will be presented. P(VDF-TrFE) copolymers exhibit unique piezoelectric properties over a wide range of temperature depending on the composition. Their properties and phase transitions are being investigated. Emphasis of the presentation will be on key results and implications. {copyright} {ital 1998 American Institute of Physics.}

  15. Ionospheric shock waves triggered by rockets

    NASA Astrophysics Data System (ADS)

    Lin, C. H.; Lin, J. T.; Chen, C. H.; Liu, J. Y.; Sun, Y. Y.; Kakinami, Y.; Matsumura, M.; Chen, W. H.; Liu, H.; Rau, R. J.

    2014-09-01

    This paper presents a two-dimensional structure of the shock wave signatures in ionospheric electron density resulting from a rocket transit using the rate of change of the total electron content (TEC) derived from ground-based GPS receivers around Japan and Taiwan for the first time. From the TEC maps constructed for the 2009 North Korea (NK) Taepodong-2 and 2013 South Korea (SK) Korea Space Launch Vehicle-II (KSLV-II) rocket launches, features of the V-shaped shock wave fronts in TEC perturbations are prominently seen. These fronts, with periods of 100-600 s, produced by the propulsive blasts of the rockets appear immediately and then propagate perpendicularly outward from the rocket trajectory with supersonic velocities between 800-1200 m s-1 for both events. Additionally, clear rocket exhaust depletions of TECs are seen along the trajectory and are deflected by the background thermospheric neutral wind. Twenty minutes after the rocket transits, delayed electron density perturbation waves propagating along the bow wave direction appear with phase velocities of 800-1200 m s-1. According to their propagation character, these delayed waves may be generated by rocket exhaust plumes at earlier rocket locations at lower altitudes.

  16. Shock Waves and Commutation Speed of Memristors

    NASA Astrophysics Data System (ADS)

    Tang, Shao; Tesler, Federico; Marlasca, Fernando Gomez; Levy, Pablo; Dobrosavljević, V.; Rozenberg, Marcelo

    2016-01-01

    Progress of silicon-based technology is nearing its physical limit, as the minimum feature size of components is reaching a mere 10 nm. The resistive switching behavior of transition metal oxides and the associated memristor device is emerging as a competitive technology for next-generation electronics. Significant progress has already been made in the past decade, and devices are beginning to hit the market; however, this progress has mainly been the result of empirical trial and error. Hence, gaining theoretical insight is of the essence. In the present work, we report the striking result of a connection between the resistive switching and shock-wave formation, a classic topic of nonlinear dynamics. We argue that the profile of oxygen vacancies that migrate during the commutation forms a shock wave that propagates through a highly resistive region of the device. We validate the scenario by means of model simulations and experiments in a manganese-oxide-based memristor device, and we extend our theory to the case of binary oxides. The shock-wave scenario brings unprecedented physical insight and enables us to rationalize the process of oxygen-vacancy-driven resistive change with direct implications for a key technological aspect—the commutation speed.

  17. Shock wave reflections in a liquid filled thin tube

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shota; Tagawa, Yoshiyuki; Kameda, Masaharu

    2013-11-01

    We investigate a behavior of an underwater shock wave in a thin glass tube using an ultra high-speed camera up to 107 frames per second. We here focus on the pressure of the reflected shock wave at interfaces (water-glass wall / water-air). A shock wave is visualized using the Background Oriented Schlieren (BOS) technique. We measure the time evolution of the shock front position and estimate the shock velocity, pressure, and internal energy as a function of the distance from the shock center. At the water-wall interface the reflected shock pressure is lower than the incident shock pressure, which agrees well with the theoretical estimation for an acoustic pressure wave. The reflected pressure at the air-water interface is much lower than the incident shock, indicating that the shape of the air-water interface may affect this reduction of the reflected pressure.

  18. Gas turbine power plant with supersonic shock compression ramps

    SciTech Connect

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

    2008-10-14

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

  19. On Reflection of Shock Waves from Boundary Layers

    NASA Technical Reports Server (NTRS)

    Liepmann, H W; Roshko, A; Dhawan, S

    1952-01-01

    Measurements are presented at Mach numbers from about 1.3 to 1.5 of reflection characteristics and the relative upstream influence of shock waves impinging on a flat surface with both laminar and turbulent boundary layers. The difference between impulse and step waves is discussed and their interaction with the boundary layer is compared. General considerations on the experimental production of shock waves from wedges and cones and examples of reflection of shock waves from supersonic shear layers are also presented.

  20. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects.

    PubMed

    Courtney, Amy C; Andrusiv, Lubov P; Courtney, Michael W

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile. PMID:22559580

  1. Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects

    NASA Astrophysics Data System (ADS)

    Courtney, Amy C.; Andrusiv, Lubov P.; Courtney, Michael W.

    2012-04-01

    This paper describes the development and characterization of modular, oxy-acetylene driven laboratory scale shock tubes. Such tools are needed to produce realistic blast waves in a laboratory setting. The pressure-time profiles measured at 1 MHz using high-speed piezoelectric pressure sensors have relevant durations and show a true shock front and exponential decay characteristic of free-field blast waves. Descriptions are included for shock tube diameters of 27-79 mm. A range of peak pressures from 204 kPa to 1187 kPa (with 0.5-5.6% standard error of the mean) were produced by selection of the driver section diameter and distance from the shock tube opening. The peak pressures varied predictably with distance from the shock tube opening while maintaining both a true blast wave profile and relevant pulse duration for distances up to about one diameter from the shock tube opening. This shock tube design provides a more realistic blast profile than current compression-driven shock tubes, and it does not have a large jet effect. In addition, operation does not require specialized personnel or facilities like most blast-driven shock tubes, which reduces operating costs and effort and permits greater throughput and accessibility. It is expected to be useful in assessing the response of various sensors to shock wave loading; assessing the reflection, transmission, and absorption properties of candidate armor materials; assessing material properties at high rates of loading; assessing the response of biological materials to shock wave exposure; and providing a means to validate numerical models of the interaction of shock waves with structures. All of these activities have been difficult to pursue in a laboratory setting due in part to lack of appropriate means to produce a realistic blast loading profile.

  2. Measurements of the equations of state and spectrum of nonideal xenon plasma under shock compression.

    PubMed

    Zheng, J; Gu, Y J; Chen, Z Y; Chen, Q F

    2010-08-01

    Experimental equations of state on generation of nonideal xenon plasma by intense shock wave compression was presented in the ranges of pressure of 2-16 GPa and temperature of 31-50 kK, and the xenon plasma with the nonideal coupling parameter Γ range from 0.6-2.1 was generated. The shock wave was produced using the flyer plate impact and accelerated up to ∼6 km/s with a two-stage light gas gun. Gaseous specimens were shocked from two initial pressures of 0.80 and 4.72 MPa at room temperature. Time-resolved spectral radiation histories were recorded by using a multiwavelength channel pyrometer. The transient spectra with the wavelength range of 460-700 nm were recorded by using a spectrometer to evaluate the shock temperature. Shock velocity was measured and particle velocity was determined by the impedance matching methods. The equations of state of xenon plasma and ionization degree have been discussed in terms of the self-consistent fluid variational theory.

  3. Measurements of the equations of state and spectrum of nonideal xenon plasma under shock compression

    SciTech Connect

    Zheng, J.; Gu, Y. J.; Chen, Z. Y.; Chen, Q. F.

    2010-08-15

    Experimental equations of state on generation of nonideal xenon plasma by intense shock wave compression was presented in the ranges of pressure of 2-16 GPa and temperature of 31-50 kK, and the xenon plasma with the nonideal coupling parameter {Gamma} range from 0.6-2.1 was generated. The shock wave was produced using the flyer plate impact and accelerated up to {approx}6 km/s with a two-stage light gas gun. Gaseous specimens were shocked from two initial pressures of 0.80 and 4.72 MPa at room temperature. Time-resolved spectral radiation histories were recorded by using a multiwavelength channel pyrometer. The transient spectra with the wavelength range of 460-700 nm were recorded by using a spectrometer to evaluate the shock temperature. Shock velocity was measured and particle velocity was determined by the impedance matching methods. The equations of state of xenon plasma and ionization degree have been discussed in terms of the self-consistent fluid variational theory.

  4. Measurements of the equations of state and spectrum of nonideal xenon plasma under shock compression.

    PubMed

    Zheng, J; Gu, Y J; Chen, Z Y; Chen, Q F

    2010-08-01

    Experimental equations of state on generation of nonideal xenon plasma by intense shock wave compression was presented in the ranges of pressure of 2-16 GPa and temperature of 31-50 kK, and the xenon plasma with the nonideal coupling parameter Γ range from 0.6-2.1 was generated. The shock wave was produced using the flyer plate impact and accelerated up to ∼6 km/s with a two-stage light gas gun. Gaseous specimens were shocked from two initial pressures of 0.80 and 4.72 MPa at room temperature. Time-resolved spectral radiation histories were recorded by using a multiwavelength channel pyrometer. The transient spectra with the wavelength range of 460-700 nm were recorded by using a spectrometer to evaluate the shock temperature. Shock velocity was measured and particle velocity was determined by the impedance matching methods. The equations of state of xenon plasma and ionization degree have been discussed in terms of the self-consistent fluid variational theory. PMID:20866920

  5. Addressing the problem of uniform converging spherical shock wave in water

    NASA Astrophysics Data System (ADS)

    Nitishinskiy, M.; Efimov, S.; Yanuka, D.; Gurovich, V. Tz.; Krasik, Ya. E.

    2016-10-01

    Time-resolved parameters of plasma compressed by a shock wave generated by the underwater electrical explosion of a spherical wire array are presented. The plasma was preliminarily formed inside a capillary placed at the equatorial plane along the axis of the array. Temporal evolution analysis of Hα and C II spectral lines showed that the plasma density increases from its initial value of ˜3 × 1017 cm-3 up to ˜5.5 × 1017 cm-3 within 300 ± 25 ns. These results were found to be in agreement with those of the model that considers the adiabatic compression of the plasma by the converging capillary walls caused by interaction with the incident shock wave with a pressure of ˜3 × 109 Pa at a radius of 1.5 mm. The latter results coincide well with those of the 1D hydrodynamic modeling, which assumes uniformity of the converging shock wave.

  6. Mechanochemistry for Shock Wave Energy Dissipation

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  7. Modeling Propagation of Shock Waves in Metals

    SciTech Connect

    Howard, W M; Molitoris, J D

    2005-08-19

    We present modeling results for the propagation of strong shock waves in metals. In particular, we use an arbitrary Lagrange Eulerian (ALE3D) code to model the propagation of strong pressure waves (P {approx} 300 to 400 kbars) generated with high explosives in contact with aluminum cylinders. The aluminum cylinders are assumed to be both flat-topped and have large-amplitude curved surfaces. We use 3D Lagrange mechanics. For the aluminum we use a rate-independent Steinberg-Guinan model, where the yield strength and shear modulus depend on pressure, density and temperature. The calculation of the melt temperature is based on the Lindermann law. At melt the yield strength and shear modulus is set to zero. The pressure is represented as a seven-term polynomial as a function of density. For the HMX-based high explosive, we use a JWL, with a program burn model that give the correct detonation velocity and C-J pressure (P {approx} 390 kbars). For the case of the large-amplitude curved surface, we discuss the evolving shock structure in terms of the early shock propagation experiments by Sakharov.

  8. Direct Visualization of Shock Waves in Supersonic Space Shuttle Flight

    NASA Technical Reports Server (NTRS)

    OFarrell, J. M.; Rieckhoff, T. J.

    2011-01-01

    Direct observation of shock boundaries is rare. This Technical Memorandum describes direct observation of shock waves produced by the space shuttle vehicle during STS-114 and STS-110 in imagery provided by NASA s tracking cameras.

  9. EXPERIMENTAL STUDY OF SHOCK WAVE DYNAMICS IN MAGNETIZED PLASMAS

    SciTech Connect

    Nirmol K. Podder

    2009-03-17

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

  10. Amorphization and nanocrystallization of silcon under shock compression

    DOE PAGES

    Remington, B. A.; Wehrenberg, C. E.; Zhao, S.; Hahn, E. N.; Kad, B.; Bringa, E. M.; Meyers, M. A.

    2015-11-06

    High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct amorphous regions were identified: (a) a bulk amorphous layer close to the surface and (b) amorphous bands initially aligned with {111} slip planes. Further increase of the laser energy leads to the re-crystallization of amorphous silicon into nanocrystals with high concentration of nano-twins. This amorphization is produced by the combined effect of high magnitude hydrostatic and shear stresses under dynamic shock compression. Shock-induced defects play a very important role in the onset of amorphization. Calculations of the free energymore » changes with pressure and shear, using the Patel-Cohen methodology, are in agreement with the experimental results. Molecular dynamics simulation corroborates the amorphization, showing that it is initiated by the nucleation and propagation of partial dislocations. As a result, the nucleation of amorphization is analyzed qualitatively by classical nucleation theory.« less

  11. Underwater Shock Wave Research Applied to Therapeutic Device Developments

    NASA Astrophysics Data System (ADS)

    Takayama, K.; Yamamoto, H.; Shimokawa, H.

    2013-07-01

    The chronological development of underwater shock wave research performed at the Shock Wave Research Center of the Institute of Fluid Science at the Tohoku University is presented. Firstly, the generation of planar underwater shock waves in shock tubes and their visualization by using the conventional shadowgraph and schlieren methods are described. Secondly, the generation of spherical underwater shock waves by exploding lead azide pellets weighing from several tens of micrograms to 100 mg, that were ignited by irradiating with a Q-switched laser beam, and their visualization by using double exposure holographic interferometry are presented. The initiation, propagation, reflection, focusing of underwater shock waves, and their interaction with various interfaces, in particular, with air bubbles, are visualized quantitatively. Based on such a fundamental underwater shock wave research, collaboration with the School of Medicine at the Tohoku University was started for developing a shock wave assisted therapeutic device, which was named an extracorporeal shock wave lithotripter (ESWL). Miniature shock waves created by irradiation with Q-switched HO:YAG laser beams are studied, as applied to damaged dysfunctional nerve cells in the myocardium in a precisely controlled manner, and are effectively used to design a catheter for treating arrhythmia.

  12. Nonequilibrium ionization phenomena behind shock waves

    SciTech Connect

    Panesi, Marco; Magin, Thierry; Huo, Winifred

    2011-05-20

    An accurate investigation of the behavior of electronically excited states of atoms and molecules in the post shock relaxation zone of a trajectory point of the FIRE II flight experiment is carried out by means of a one-dimensional flow solver coupled to a collisional-radiative model. In the rapidly ionizing regime behind a strong shock wave, the high lying bound electronic states of atoms are depleted. This leads the electronic energy level populations of atoms to depart from Boltzmann distributions which strongly affects the non-equilibrium ionization process as well as the radiative signature. The importance of correct modeling of the interaction of radiation and matter is discussed showing a strong influence on the physico-chemical properties of the gas. The paper clearly puts forward the shortcomings of the simplified approach often used in literature which strongly relies on the escape factors to characterize the optical thickness of the gas.

  13. Control and reduction of unsteady pressure loads in separated shock wave turbulent boundary layer interaction

    NASA Technical Reports Server (NTRS)

    Dolling, David S.; Barter, John W.

    1995-01-01

    The focus was on developing means of controlling and reducing unsteady pressure loads in separated shock wave turbulent boundary layer interactions. Section 1 describes how vortex generators can be used to effectively reduce loads in compression ramp interaction, while Section 2 focuses on the effects of 'boundary-layer separators' on the same interaction.

  14. Wave and particle evolution downstream of quasi-perpendicular shocks

    NASA Technical Reports Server (NTRS)

    Mckean, M. E.; Omidi, N.; Krauss-Varban, D.; Karimabadi, H.

    1995-01-01

    Distributions of ions heated in quasi-perpendicular bow shocks have large perpendicular temperature anisotropies that provide free energy for the growth of Alfven ion cyclotron (AIC) and mirror waves. These modes are often obsreved in the Earth's magnetosheath. Using two-dimensional hybrid simulations, we show that these waves are produced near the shock front and convected downstream rather than being produced locally downstream. The wave activity reduces the proton anisotropy to magnetosheath levels within a few tens of gyroradii of the shock but takes significantly longer to reduce the anisotropy of He(++) ions. The waves are primarily driven by proton anisotropy and the dynamics of the helium ions is controlled by the proton waves. Downstream of high Mach number shocks, mirror waves compete effectively with AIC waves. Downstream of low Mach number shocks, AIC waves dominate.

  15. Doppler effect for an optical discharge source of shock waves

    SciTech Connect

    Tishchenko, V N

    2005-11-30

    The Doppler effect for a moving pulsating optical discharge producing periodic shock waves is considered. The manifestations of the effect are limited by the wave merging mechanism. The validity conditions were found for the effect in the case of a pulsating source of shock waves. (interaction of laser radiation with matter. laser plasma)

  16. Turbulence generation by a shock wave interacting with a random density inhomogeneity field

    NASA Astrophysics Data System (ADS)

    Huete Ruiz de Lira, C.

    2010-12-01

    When a planar shock wave interacts with a random pattern of pre-shock density non-uniformities, it generates an anisotropic turbulent velocity/vorticity field. This turbulence plays an important role in the early stages of the mixing process in a compressed fluid. This situation emerges naturally in a shock interaction with weakly inhomogeneous deuterium-wicked foam targets in inertial confinement fusion and with density clumps/clouds in astrophysics. We present an exact small-amplitude linear theory describing such an interaction. It is based on the exact theory of time and space evolution of the perturbed quantities behind a corrugated shock front for a single-mode pre-shock non-uniformity. Appropriate mode averaging in two dimensions results in closed analytical expressions for the turbulent kinetic energy, degree of anisotropy of velocity and vorticity fields in the shocked fluid, shock amplification of the density non-uniformity and sonic energy flux radiated downstream. These explicit formulae are further simplified in the important asymptotic limits of weak/strong shocks and highly compressible fluids. A comparison with the related problem of a shock interacting with a pre-shock isotropic vorticity field is also presented.

  17. Deformation twinning activated α --> ω transformation in titanium under shock compression

    NASA Astrophysics Data System (ADS)

    Zong, Hongxiang; Lookman, Turab

    Materials dynamics, especially the behavior of solids under extreme compression, is a topic of broad scientific and technological interest. However, less is known of the role of grain boundary structures on the shock response of hexagonal-close-packed metals. We use molecular dynamics simulations to study deformation mechanisms in shock compressed Ti bicrystals containing three types of grain boundary (GB) microstructures, i.e., coherent twin boundaries (CTBs), symmetric incoherent twin boundaries (ITB) and {1-210}asymmetric tilt grain boundaries. Our results show that both dislocation activity and the α -> ω phase transformation in Ti are sensitive to the GB characteristics. In particular, we find that the elastic shock wave can readily trigger the α -> ω transformation at CTBs but not at the other two GBs, and the activation of the α -> ω transformation at CTBs leads to considerable wave attenuation (i.e., the elastic precursor decay). Combined with first principle calculations, we find that CTBs can facilitate the overcoming of the energy barrier for the α -> ω transformation. Our findings have potential implications for interface engineering and materials design under extreme conditions.

  18. Supersonic shock wave/vortex interaction

    NASA Technical Reports Server (NTRS)

    Settles, G. S.; Cattafesta, L.

    1993-01-01

    Although shock wave/vortex interaction is a basic and important fluid dynamics problem, very little research has been conducted on this topic. Therefore, a detailed experimental study of the interaction between a supersonic streamwise turbulent vortex and a shock wave was carried out at the Penn State Gas Dynamics Laboratory. A vortex is produced by replaceable swirl vanes located upstream of the throat of various converging-diverging nozzles. The supersonic vortex is then injected into either a coflowing supersonic stream or ambient air. The structure of the isolated vortex is investigated in a supersonic wind tunnel using miniature, fast-response, five-hole and total temperature probes and in a free jet using laser Doppler velocimetry. The cases tested have unit Reynolds numbers in excess of 25 million per meter, axial Mach numbers ranging from 2.5 to 4.0, and peak tangential Mach numbers from 0 (i.e., a pure jet) to about 0.7. The results show that the typical supersonic wake-like vortex consists of a non-isentropic, rotational core, where the reduced circulation distribution is self similar, and an outer isentropic, irrotational region. The vortex core is also a region of significant turbulent fluctuations. Radial profiles of turbulent kinetic energy and axial-tangential Reynolds stress are presented. The interactions between the vortex and both oblique and normal shock waves are investigated using nonintrusive optical diagnostics (i.e. schlieren, planar laser scattering, and laser Doppler velocimetry). Of the various types, two Mach 2.5 overexpanded-nozzle Mach disc interactions are examined in detail. Below a certain vortex strength, a 'weak' interaction exists in which the normal shock is perturbed locally into an unsteady 'bubble' shock near the vortex axis, but vortex breakdown (i.e., a stagnation point) does not occur. For stronger vortices, a random unsteady 'strong' interaction results that causes vortex breakdown. The vortex core reforms downstream of

  19. A numerical study of shock wave diffraction by a circular cylinder

    NASA Technical Reports Server (NTRS)

    Yang, J.-Y.; Liu, Y.; Lomax, H.

    1986-01-01

    The nonstationary shock wave diffraction patterns generated by a blast wave impinging on a circular cylinder are numerically simulated using a second-order hybrid upwind method for solving the two-dimensional inviscid compressible Euler equations of gasdynamics. The complete diffraction patterns, including the transition from regular to Mach reflection, trajectory of the Mach triple point and the complex shock-on-shock interaction at the wake region resulting from the Mach shocks collision behind the cylinder are reported in detail. Pressure-time history and various contour plots are also included. Comparison between the work of Bryson and Gross (1961) which included both experimental schlieren pictures and theoretical calculations using Whitham's ray-shock theory and results of the present finite difference computation indicate good agreement in every aspect except for some nonideal gas and viscous effects which are not accounted for by the Euler equations.

  20. Electrostatic waves in the bow shock at Uranus

    NASA Technical Reports Server (NTRS)

    Moses, S. L.; Coroniti, F. V.; Kennel, C. F.; Bagenal, F.; Lepping, R. P.

    1989-01-01

    Electrostatic emissions measured by the Voyager 2 plasma wave detector (PWS) during the inbound crossing of the Uranian bow shock are shown to differ in some aspects from the waves measured during bow shock crossings at Jupiter and Saturn. The wave amplitudes in the foot of the bow shock at Uranus are in general much lower than those detected at the other outer planets due to the unusually enhanced solar wind ion temperature during the crossing. This reduces the effectiveness of wave-particle interactions in heating the incoming electrons. Strong wave emissions are observed in the shock ramp that possibly arise from currents producing a Buneman mode instability. Plasma instrument (PLS) and magnetometer (MAG) measurements reveal a complicated shock structure reminiscent of computer simulations of high-Mach number shocks when the effects of anomalous resistivity are reduced, and are consistent with high ion temperatures restricting the growth of electrostatic waves.

  1. Electrostatic waves in the bow shock at Uranus

    SciTech Connect

    Moses, S.L.; Coroniti, F.V.; Kennel, C.F.; Scarf, F.L. ); Bagenal, F. ); Lepping, R.P. ); Quest, K.B. ); Kurth, W.S. )

    1989-10-01

    Electrostatic emissions measured by the Voyager 2 plasma wave detector (PWS) during the inbound crossing of the Uranian bow shock are shown to differ in some aspects from the waves measured during bow shock crossings at Jupiter and Saturn. The wave amplitudes in the foot of the bow shock at Uranus are in general much lower than those detected at the other out planets due to the unusually enhanced solar wind ion temperature during the crossing. This reduces the effectiveness of wave-particle interactions in heating the incoming electrons. Strong wave emissions are observed in the shock ramp that possibly arise from currents producing a Buneman mode instability. Plasma instrument (PLS) and magnetometer (MAG) measurements reveal a complicated shock structure reminiscent of computer simulations of high-Mach number shocks when the effects of anomalous resistivity are reduced, and are consistent with high ion temperatures restricting the growth of electrostatic waves.

  2. Local stability analysis for a planar shock wave

    NASA Technical Reports Server (NTRS)

    Salas, M. D.

    1984-01-01

    A procedure to study the local stability of planar shock waves is presented. The procedure is applied to a Rankine-Hugoniot shock in a divergent/convergent nozzle, to an isentropic shock in a divergent/convergent nozzle, and to Rankine-Hugoniot shocks attached to wedges and cones. It is shown that for each case, the equation governing the shock motion is equivalent to the damped harmonic oscillator equation.

  3. Propagation of compression waves in bubbly liquid with hydrate formation

    NASA Astrophysics Data System (ADS)

    Shagapov, V. Sh.; Lepikhin, S. A.; Chiglintsev, I. A.

    2010-06-01

    The dynamics of planar one-dimensional shock waves applied to the available experimental data for the water-Freon system is studied on the basis of the theoretical model of the bubbly liquid refined with regard for a possible hydrate formation. A scheme is proposed for considering the fragmentation of bubbles in the shock wave, which is one of the main factors of the intensification of the hydrate formation process with the growth of the shock wave amplitude.

  4. Internal energy relaxation in shock wave structure

    SciTech Connect

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

    2013-12-15

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

  5. Laser-driven flyer plates for shock compression spectroscopy

    NASA Astrophysics Data System (ADS)

    Dlott, Dana; Shaw, William; Curtis, Alexander; Banishev, Alexandr

    2013-06-01

    A laser-driven mini flyer plate system was developed for shock compression spectroscopy. A commercial one-box 2J YAG laser produces a homogeneous top hat beam with a diffractive optic. An 8 GHz PDV characterizes flyer velocity profiles up to 5 km/s. Flyers are routinely launched with velocities reproducible to + ∖ -1%, and the 1 mm diameter flyers have enough energy to initiate energetic materials. High-speed spectroscopic diagnostics have been synchronized. Design elements such as diameter, thickness, laser pulse duration, substrate size, and so on will be discussed. Illustrations will be presented, including monitoring shock front structures with embedded optical gauges, and understanding mechanisms of reactive nanomaterial impact initiation. Supported by ARO W911NF-10-1-0072, AFOSR FA9550-09-1-0163, DTRA HDTRA1-12-1-0011 and NNSA Carnegie-DOE Alliance Center DOE CIW 4-3253-13.

  6. [Physical parameters of extracorporeal shock waves].

    PubMed

    Maier, M; Ueberle, F; Rupprecht, G

    1998-10-01

    Prerequisites for the successful investigation of the mechanism of action of ESWT (extracorporeal shockwave therapy) and the establishment of treatment standards, are the ability to measure, and a knowledge of, the physical parameters involved. The most accurate measurements are obtained with laser hydrophones. Various parameters (amplitude, rise time, pulse width, pressure pulse decay, rarification phase) of a typical shock wave can thus be determined. These can then be used to calculate energy flux density, focal extent, focal volume and as well as focal energy, effective energy in a defined area, and effective biological energy. These parameters can be utilized to work out a theoretical treatment protocol.

  7. Nonequilibrium processes in a shock wave profile

    NASA Astrophysics Data System (ADS)

    Bashlykov, A. M.; Velikodnyi, V. Iu.

    1989-03-01

    A modified Tamm-Mott-Smith approach is used to study the distribution of heat fluxes in a shock wave profile and their relationship with the distribution of partial temperature in gas mixtures. Results are presented on changes of partial and mean temperature, and heat fluxes in an He-Xe mixture at a Mach number of 4.4 and in an He-Ar mixture at a Mach number of 1.58. Conditions are established under which the heat flux of the heavy component of the mixture has the same sign as the gradient of its partial temperature.

  8. Current topics in shock waves; Proceedings of the International Symposium on Shock Waves and Shock Tubes, 17th, Lehigh University, Bethlehem, PA, July 17-21, 1989

    SciTech Connect

    Kim, Y.W.

    1990-01-01

    Various papers on shock waves are presented. The general topics addressed include: shock formation, focusing, and implosion; shock reflection and diffraction; turbulence; laser-produced plasmas and waves; ionization and shock-plasma interaction; chemical kinetics, pyrolysis, and soot formation; experimental facilities, techniques, and applications; ignition of detonation and combustion; particle entrainment and shock propagation through particle suspension; boundary layers and blast simulation; computational methods and numerical simulation.

  9. Electrohydraulic shock wave generation as a means to increase intrinsic permeability of mortar

    SciTech Connect

    Maurel, O.; Reess, T.; Matallah, M.; De Ferron, A.; Chen, W.; La Borderie, C.; Pijaudier-Cabot, G.; Jacques, A.; Rey-Bethbeder, F.

    2010-12-15

    This article discusses the influence of compressive shock waves on the permeability of cementitious materials. Shock waves are generated in water by Pulsed Arc Electrohydraulic Discharges (PAED). The practical aim is to increase the intrinsic permeability of the specimens. The maximum pressure amplitude of the shock wave is 250 MPa. It generates damage in the specimens and the evolution of damage is correlated with the intrinsic permeability of the mortar. A threshold of pressure is observed. From this threshold, the increase of permeability is linear in a semi-log plot. The influence of repeated shocks on permeability is also discussed. Qualitative X Ray Tomography illustrates the evolution of the microstructure of the material leading to the increase of permeability. Comparative results from mercury intrusion porosimetry (MIP) show that the micro-structural damage process starts at the sub-micrometric level and that the characteristic size of pores of growing volume increases.

  10. Planar and nonplanar ion acoustic shock waves in relativistic degenerate astrophysical electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Ata-ur-Rahman, Ali, S.; Mirza, Arshad M.; Qamar, A.

    2013-04-01

    We have studied the propagation of ion acoustic shock waves involving planar and non-planar geometries in an unmagnetized plasma, whose constituents are non-degenerate ultra-cold ions, relativistically degenerate electrons, and positrons. By using the reductive perturbation technique, Korteweg-deVries Burger and modified Korteweg-deVries Burger equations are derived. It is shown that only compressive shock waves can propagate in such a plasma system. The effects of geometry, the ion kinematic viscosity, and the positron concentration are examined on the ion acoustic shock potential and electric field profiles. It is found that the properties of ion acoustic shock waves in a non-planar geometry significantly differ from those in planar geometry. The present study has relevance to the dense plasmas, produced in laboratory (e.g., super-intense laser-dense matter experiments) and in dense astrophysical objects.

  11. Planar and nonplanar ion acoustic shock waves in relativistic degenerate astrophysical electron-positron-ion plasmas

    SciTech Connect

    Ata-ur-Rahman,; Qamar, A.; Ali, S.; Mirza, Arshad M.

    2013-04-15

    We have studied the propagation of ion acoustic shock waves involving planar and non-planar geometries in an unmagnetized plasma, whose constituents are non-degenerate ultra-cold ions, relativistically degenerate electrons, and positrons. By using the reductive perturbation technique, Korteweg-deVries Burger and modified Korteweg-deVries Burger equations are derived. It is shown that only compressive shock waves can propagate in such a plasma system. The effects of geometry, the ion kinematic viscosity, and the positron concentration are examined on the ion acoustic shock potential and electric field profiles. It is found that the properties of ion acoustic shock waves in a non-planar geometry significantly differ from those in planar geometry. The present study has relevance to the dense plasmas, produced in laboratory (e.g., super-intense laser-dense matter experiments) and in dense astrophysical objects.

  12. Solitary versus shock wave acceleration in laser-plasma interactions.

    PubMed

    Macchi, Andrea; Nindrayog, Amritpal Singh; Pegoraro, Francesco

    2012-04-01

    The excitation of nonlinear electrostatic waves, such as shock and solitons, by ultraintense laser interaction with overdense plasmas and related ion acceleration are investigated by numerical simulations. Stability of solitons and formation of shock waves is strongly dependent on the velocity distribution of ions. Monoenergetic components in ion spectra are produced by "pulsed" reflection from solitary waves. Possible relevance to recent experiments on "shock acceleration" is discussed. PMID:22680581

  13. Shock waves and nucleosynthesis in type II supernovae

    NASA Technical Reports Server (NTRS)

    Aufderheide, M. B.; Baron, E.; Thielemann, F.-K.

    1991-01-01

    In the study of nucleosynthesis in type II SN, shock waves are initiated artificially, since collapse calculations do not, as yet, give self-consistent shock waves strong enough to produce the SN explosion. The two initiation methods currently used by light-curve modelers are studied, with a focus on the peak temperatures and the nucleosynthetic yields in each method. The various parameters involved in artificially initiating a shock wave and the effects of varying these parameters are discussed.

  14. Modeling of strongly-nonlinear wave propagation using the extended Rankine-Hugoniot shock relations

    NASA Astrophysics Data System (ADS)

    Lee, J.-W.; Ohm, W.-S.; Shim, W.

    2015-10-01

    This paper presents a computational scheme solely based on the Rankine-Hugoniot shock relations to describe the propagation of strongly-nonlinear waves in fluids, the amplitude of which is so great that second-order approximations such as the weak shock theory and the Burgers equation do not apply. The Rankine-Hugoniot relations are three algebraic equations connecting the flow variables (pressure, density, particle velocity, and energy) across a shock. What is not well known is that the Rankine-Hugoniot relations can be used to compute the nonlinear evolution of the continuous segment of a wave, if the continuous segment can be approximated by a succession of infinitesimal compression shocks [Ya. B. Zel'dovich and Yu. P. Raizer, Physics of Shock Waves and High-Temperature Hydrodynamic Phenomena (Dover, New York, 2002), pp. 85-86]. We further extend this idea to the other continuous segment that can be discretized into a series of infinitesimal rarefaction shocks. The discretization of a waveform and the subsequent application of the Rankine-Hugoniot relations lead to a Riemann problem that conveniently treats continuous segments and real shocks in the same manner. Our computational scheme distinguishes itself from the conventional Riemann problem in that shocks are treated as particles, which facilitates an enormous saving in computation time. The scheme is verified against the 1-D Riemann solver for the case of strong blast waves.

  15. Vibrational spectroscopy of shock-compressed liquid CO

    SciTech Connect

    Moore, D.S.; Schmidt, S.C.; Shaw, M.S.; Johnson, J.D.

    1991-01-01

    Single-pulse, multiplex, coherent anti-Stokes Raman spectroscopy (CARS) was used to observe the vibrational spectra of liquid CO shock compressed to several pressures and temperatures up to 9.9 GPa and 2010 K. The experimental spectra were compared to synthetic spectra calculated using a semiclassical model for CARS intensities and estimated vibrational frequencies, peak Raman susceptibilities and Raman line widths. A comparison of these data with result in the isoelectronic and materially very similar N{sub 2} show a significant difference in vibrational frequency shift with pressure. 21 refs., 2 figs.

  16. Modeling compressive reaction and estimating model uncertainty in shock loaded porous samples of Hexanitrostilbene (HNS)

    NASA Astrophysics Data System (ADS)

    Brundage, Aaron; Gump, Jared

    2011-06-01

    Neat pressings of HNS powders have been used in many explosive applications for over 50 years. However, characterization of its crystalline properties has lagged that of other explosives, and the solid stress has been inferred from impact experiments or estimated from mercury porosimetry. This lack of knowledge of the precise crystalline isotherm can contribute to large model uncertainty in the reacted response of pellets to shock impact. At high impact stresses, deflagration-to-detonation transition (DDT) processes initiated by compressive reaction have been interpreted from velocity interferometry at the surface of distended HNS-FP pellets. In particular, the Baer-Nunziato multiphase model in CTH, Sandia's Eulerian, finite volume shock propagation code, was used to predict compressive waves in pellets having approximately a 60% theoretical maximum density (TMD). These calculations were repeated with newly acquired isothermal compression measurements of fine-particle HNS using diamond anvil cells to compress the sample and powder x-ray diffraction to obtain the sample volume at each pressure point. Hence, estimating the model uncertainty provides a simple method for conveying the impact of future model improvements based upon new experimental data.

  17. Modeling compressive reaction and estimating model uncertainty in shock loaded porous samples of hexanitrostilbene (HNS)

    NASA Astrophysics Data System (ADS)

    Brundage, Aaron L.; Gump, Jared C.

    2012-03-01

    Neat pressings of HNS powders have been used in many explosive applications for over 50 years. However, characterization of its crystalline properties has lagged that of other explosives, and the solid stress has been inferred from impact experiments or estimated from mercury porosimetry. This lack of knowledge of the precise crystalline isotherm can contribute to large model uncertainty in the reacted response of pellets to shock impact. At high impact stresses, deflagration-to-detonation transition (DDT) processes initiated by compressive reaction have been interpreted from velocity interferometry at the surface of distended HNS-FP pellets. In particular, the Baer-Nunziato multiphase model in CTH, Sandia's Eulerian, finite volume shock propagation code, was used to predict compressive waves in pellets having approximately a 60% theoretical maximum density (TMD). These calculations were repeated with newly acquired isothermal compression measurements of fineparticle HNS using diamond anvil cells to compress the sample and powder x-ray diffraction to obtain the sample volume at each pressure point. Hence, estimating the model uncertainty provides a simple method for conveying the impact of future model improvements based upon new experimental data.

  18. Biodamage via shock waves initiated by irradiation with ions.

    PubMed

    Surdutovich, Eugene; Yakubovich, Alexander V; Solov'yov, Andrey V

    2013-01-01

    Radiation damage following the ionising radiation of tissue has different scenarios and mechanisms depending on the projectiles or radiation modality. We investigate the radiation damage effects due to shock waves produced by ions. We analyse the strength of the shock wave capable of directly producing DNA strand breaks and, depending on the ion's linear energy transfer, estimate the radius from the ion's path, within which DNA damage by the shock wave mechanism is dominant. At much smaller values of linear energy transfer, the shock waves turn out to be instrumental in propagating reactive species formed close to the ion's path to large distances, successfully competing with diffusion.

  19. Shock wave processes in collisional gas particle mixtures

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  20. Magnetosonic shock wave in collisional pair-ion plasma

    NASA Astrophysics Data System (ADS)

    Adak, Ashish; Sikdar, Arnab; Ghosh, Samiran; Khan, Manoranjan

    2016-06-01

    Nonlinear propagation of magnetosonic shock wave has been studied in collisional magnetized pair-ion plasma. The masses of both ions are same but the temperatures are slightly different. Two fluid model has been taken to describe the model. Two different modes of the magnetosonic wave have been obtained. The dynamics of the nonlinear magnetosonic wave is governed by the Korteweg-de Vries Burgers' equation. It has been shown that the ion-ion collision is the source of dissipation that causes the Burgers' term which is responsible for the shock structures in equal mass pair-ion plasma. The numerical investigations reveal that the magnetosonic wave exhibits both oscillatory and monotonic shock structures depending on the strength of the dissipation. The nonlinear wave exhibited the oscillatory shock wave for strong magnetic field (weak dissipation) and monotonic shock wave for weak magnetic field (strong dissipation). The results have been discussed in the context of the fullerene pair-ion plasma experiments.

  1. Augmented Shock Wave Severance of Materials

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.; Schimmel, Morry L.

    1995-01-01

    This paper describes a new approach for severing or weakening a variety of materials. The technique employs embedding explosive cords into parallel grooves that are cut into a surface of a material. The cords are initiated simultaneously to produce shock waves that progress toward the centerline between the cords and the lower surface of the material. Intersecting incident and reflected waves augment at the centerline to fail or weaken the material in tension. No harmful debris is produced on the opposite side of the material from the explosive cords. The primary focus of the effort described in this paper was to fracture the F-16 aircraft trilaminate canopy. Also, complete severance was achieved in 2024-T4 aluminum plate stock. Possible applications are through canopy egress and crew module severance from military aircraft and separation of rocket vehicle stages and payloads. This approach offers important advantages over explosive methods currently in use.

  2. Brane-induced-gravity shock waves.

    PubMed

    Kaloper, Nemanja

    2005-05-13

    We construct exact gravitational field solutions for a relativistic particle localized on a tensional brane in brane-induced gravity. They are a generalization of gravitational shock waves in 4D de Sitter space. We provide the metrics for both the normal branch and the self-inflating branch Dvali-Gabadadze-Porrati brane worlds, and compare them to the 4D Einstein gravity solution and to the case when gravity resides only in the 5D bulk, without any brane-localized curvature terms. At short distances the wave profile looks the same as in four dimensions. The corrections appear only far from the source, where they differ from the long distance corrections in 4D de Sitter space. We also discover a new nonperturbative channel for energy emission into the bulk from the self-inflating [corrected] branch, when gravity is modified at the de Sitter radius.

  3. Developments in strong shock wave position tracking

    NASA Astrophysics Data System (ADS)

    Rae, Philip; Glover, Brain; Perry, Lee; WX-6; WX-7 Team

    2011-06-01

    This poster will highlight several modified techniques to allow the position vs. time to be tracked in strong shock situations (such as detonation). Each is a modification or improvement of existing ideas either making use of advances in specialist materials availability or recent advances in electronics.) Shorting embedded mini-coaxial cable with a standing microwave pattern. This technique is a modified version of an old LANL method of shock position tracking making use of a traveling short imposed in an embedded coaxial cable. A high frequency standing wave (3-8GHz) is present in the cable and the moving short position can be tracked by monitoring the output voltage envelope as a function of time. A diode detector is used to allow the envelope voltage to be monitored on a regular low frequency digitizer significantly reducing the cost. The small and cheap high frequency voltage generators now available allow much greater spatial resolution than possible previously. 2) Very thin shorting resistance track gauges. Parallel tracks of constantan resistance material are etched on a thin dielectric substrate. The gauges are less than 0.2 mm thick. The ionized gas present in a detonation front sweeps up the tracks lowering the measured resistance. A potential divider circuit allows the shock position vs. time to be monitored on a regular digitizer after easy calibration. The novel feature is the thin section of the gauge producing minimal perturbation in the detonation front.

  4. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

    Sonneborn, George (Technical Monitor); Raymond, John C.

    2004-01-01

    The FUSE data have been reduced, and a paper on the results is in progress. The main results have been presented in a poster at the January 2004 AAS meeting and an ApJ paper in press. The primary result is that the widths of the 0 VI lines in the NW filament are a bit less than the width expected if the oxygen kinetic temperature is 16 times the proton temperature (mass proportional heating). This is at variance with measurements of shocks in the heliosphere, where preferential heating of oxygen and other heavy species is observed. The paper discusses the theoretical implications for collisionless shock wave physics. A secondary result is that no O VI emission was observed from the NE filament. While the very different particle distribution in that region can partially account for the weakness of the O VI lines, the simplest interpretation is that the pre-shock density in the NE is less than 0.22 times the density in the NW.

  5. Radial Shock Wave Devices Generate Cavitation

    PubMed Central

    Császár, Nikolaus B. M.; Angstman, Nicholas B.; Milz, Stefan; Sprecher, Christoph M.; Kobel, Philippe; Farhat, Mohamed; Furia, John P.; Schmitz, Christoph

    2015-01-01

    Background Conflicting reports in the literature have raised the question whether radial extracorporeal shock wave therapy (rESWT) devices and vibrating massage devices have similar energy signatures and, hence, cause similar bioeffects in treated tissues. Methods and Findings We used laser fiber optic probe hydrophone (FOPH) measurements, high-speed imaging and x-ray film analysis to compare fundamental elements of the energy signatures of two rESWT devices (Swiss DolorClast; Electro Medical Systems, Nyon, Switzerland; D-Actor 200; Storz Medical, Tägerwillen, Switzerland) and a vibrating massage device (Vibracare; G5/General Physiotherapy, Inc., Earth City, MO, USA). To assert potential bioeffects of these treatment modalities we investigated the influence of rESWT and vibrating massage devices on locomotion ability of Caenorhabditis elegans (C. elegans) worms. Results FOPH measurements demonstrated that both rESWT devices generated acoustic waves with comparable pressure and energy flux density. Furthermore, both rESWT devices generated cavitation as evidenced by high-speed imaging and caused mechanical damage on the surface of x-ray film. The vibrating massage device did not show any of these characteristics. Moreover, locomotion ability of C. elegans was statistically significantly impaired after exposure to radial extracorporeal shock waves but was unaffected after exposure of worms to the vibrating massage device. Conclusions The results of the present study indicate that both energy signature and bioeffects of rESWT devices are fundamentally different from those of vibrating massage devices. Clinical Relevance Prior ESWT studies have shown that tissues treated with sufficient quantities of acoustic sound waves undergo cavitation build-up, mechanotransduction, and ultimately, a biological alteration that “kick-starts” the healing response. Due to their different treatment indications and contra-indications rESWT devices cannot be equated to vibrating

  6. DDT modeling and shock compression experiments of porous or damaged energetic materials

    SciTech Connect

    Baer, M.R.; Anderson, M.U.; Graham, R.A.

    1994-05-01

    In this presentation, we present modeling of DDT in porous energetic materials and experimental studies of a time-resolved, shock compression of highly porous inert and reactive materials. This combined theoretical and experimental studies explore the nature of the microscale processes of consolidation, deformation and reaction which are key features of the shock response of porous or damaged energetic materials. The theoretical modeling is based on the theory of mixtures in which multiphase mixtures are treated in complete nonequilibrium allowing for internal boundary effects associated mass/momentum and energy exchange between phases, relative flow, rate-dependent compaction behavior, multistage chemistry and interphase boundary effects. Numerous studies of low-velocity impacts using a high resolution adaptive finite element method are presented which replicate experimental observations. The incorporation of this model into multi-material hydrocode analysis will be discussed to address the effects of confinement and its influence on accelerated combustion behavior. The experimental studies will focus on the use of PVDF piezoelectric polymer stress-rate gauge to precisely measure the input and propagating shock stress response of porous materials. In addition to single constituent porous materials, such as granular HMX, we have resolved shock waves in porous composite intermetallic powders that confirm a dispersive wave nature which is highly morphologically and material dependent. This document consists of viewgraphs from the poster session.

  7. Confinement effects of shock waves on laser-induced plasma from a graphite target

    SciTech Connect

    Huang, Feiling; Liang, Peipei; Yang, Xu; Cai, Hua; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian

    2015-06-15

    The spatial confinement effects of shock waves on the laser-induced plasma (LIP) from a graphite target in air were studied by probe beam deflection (PBD) measurements and optical emission spectroscopy (OES). A clear relationship between the confinement of the LIP by the shock wave and the effects on the LIP emission was observed, and the underlying mechanisms are discussed. PBD monitoring revealed that the laser-ablation induced shock wave could be well analogized to the shock wave generated by a point explosion and would be reflected by a block. OES measurements indicated that the optical emission of the LIP exhibited significant variations with the block placement. A first enhancement and then a fast decay of CN molecular emission as well as a suppression of carbon atomic emission were observed in the presence of the block. The results revealed that the reflected shock wave spatially confined the expansion of the LIP and compressed the LIP after encountering it, pushing back the species of the LIP and changing the density of the LIP species including luminous carbon atoms and CN molecules. It is suggested that the change of the LIP emission is attributed to the density variation of the LIP species due to the compression of the LIP and the reactions occurring in the plasma.

  8. Experimental particle acceleration by water evaporation induced by shock waves

    NASA Astrophysics Data System (ADS)

    Scolamacchia, T.; Alatorre Ibarguengoitia, M.; Scheu, B.; Dingwell, D. B.; Cimarelli, C.

    2010-12-01

    condensation front exhibited large accelerations, with velocity varying from few tens of m/s up to 479 (±0.5) m/s, at distances of 1.5 (±0.3) cm and in times of 0.1 ms. This process preceded the appearance of the Ar front. Our first results suggest that the evaporation of moisture induced by compression waves associated with the air shock is able to accelerate particles (ca.100s microns in size) efficiently, at short distances. This process could have broader implications in active volcanic areas where shock waves are generated, for the damage that may follow.

  9. Detonation wave compression in gas turbines

    NASA Technical Reports Server (NTRS)

    Wortman, A.

    1986-01-01

    A study was made of the concept of augmenting the performance of low pressure ratio gas turbines by detonation wave compression of part of the flow. The concept exploits the constant volume heat release of detonation waves to increase the efficiency of the Brayton cycle. In the models studied, a fraction of the compressor output was channeled into detonation ducts where it was processed by transient transverse detonation waves. Gas dynamic studies determined the maximum cycling frequency of detonation ducts, proved that upstream propagation of pressure pulses represented no problems and determined the variations of detonation duct output with time. Mixing and wave compression were used to recombine the combustor and detonation duct flows and a concept for a spiral collector to further smooth the pressure and temperature pulses was presented as an optional component. The best performance was obtained with a single firing of the ducts so that the flow could be re-established before the next detonation was initiated. At the optimum conditions of maximum frequency of the detonation ducts, the gas turbine efficiency was found to be 45 percent while that of a corresponding pressure ratio 5 conventional gas turbine was only 26%. Comparable improvements in specific fuel consumption data were found for gas turbines operating as jet engines, turbofans, and shaft output machines. Direct use of the detonation duct output for jet propulsion proved unsatisfactory. Careful analysis of the models of the fluid flow phenomena led to the conclusion that even more elaborate calculations would not diminish the uncertainties in the analysis of the system. Feasibility of the concept to work as an engine now requires validation in an engineering laboratory experiment.

  10. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, R.F.

    1983-10-18

    An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

  11. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, R.F.

    1987-03-10

    An apparatus is disclosed for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously. 3 figs.

  12. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, Robert F.

    1987-01-01

    An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

  13. Irregular Reflection of Acoustical Shock Waves and von Neumann Paradox

    NASA Astrophysics Data System (ADS)

    Baskar, S.; Coulouvrat, F.; Marchiano, R.

    2006-05-01

    We investigate the reflection of weak acoustical shock waves grazing over a rigid surface. We define a critical parameter and examine the different types of reflection structure depending on this parameter. The study of the step shock is then extended to both N-waves and periodic saw-tooth waves, which are more realistic from an acoustical point of view. The numerical simulations reveal new reflection structures for these two waves which are not observed for step shocks. The results of the model are finally compared for periodic saw-tooth waves to ultrasonic experiments.

  14. Short- and medium-range orders in Cu46Zr54 metallic glasses under shock compression

    NASA Astrophysics Data System (ADS)

    Jian, W. R.; Yao, X. H.; Wang, L.; Tang, X. C.; Luo, S. N.

    2015-07-01

    We investigate short- and medium-range orders in Cu46Zr54 metallic glasses, as represented by icosahedra and icosahedron networks, respectively, under shock compression with molecular dynamics simulations. Complementary isothermal compression and isobaric heating simulations reveal that compression below 60 GPa gives rise to increased coordination and thus high-coordination-number Voronoi polyhedra, such as icosahedra; however, pressure-induced collapse or thermal disintegration of icosahedra (and subsequently, icosahedron networks) occurs at pressures above 60 GPa or at melting, accompanied by free volume increase. The evolutions of the short- and medium-range orders upon shock loading are the effects of compression combined with shock-induced melting. The structural changes are partially reversible for weak shocks without melting (below 60 GPa) and irreversible for strong shocks. Crystallization does not occur under isothermal or shock compression at molecular dynamics scales.

  15. Interplanetary shock waves and the structure of solar wind disturbances

    NASA Technical Reports Server (NTRS)

    Hundhausen, A. J.

    1972-01-01

    Observations and theoretical models of interplanetary shock waves are reviewed, with emphasis on the large-scale characteristics of the associated solar wind disturbances and on the relationship of these disturbances to solar activity. The sum of observational knowledge indicates that shock waves propagate through the solar wind along a broad, roughly spherical front, ahead of plasma and magnetic field ejected from solar flares. Typically, the shock front reaches 1 AU about two days after its flare origin, and is of intermediate strength. Not all large flares produce observable interplanetary shock waves; the best indicator of shock production appears to be the generation of both type 2 and type 4 radio bursts by a flare. Theoretical models of shock propagation in the solar wind can account for the typically observed shock strength, transit time, and shape.

  16. Response of magnesium single crystals to shock-wave loading at normal and elevated temperatures

    NASA Astrophysics Data System (ADS)

    Garkushin, G.; Kanel, G.; Savinykh, A.; Razorenov, S.; Jones, D.; Proud, W.

    2013-06-01

    Magnesium single crystals, 0.2 mm to 3 mm thick, were shock loaded along the two axes, a, c and the direction at 45 degrees to the c-axis. At the room temperature the response is very similar to that observed by Pope and Johnson for beryllium single crystals (1974). Shock compression along the c-axis causes inelastic deformation by means of pyramidal slip and twinning and is associated with the largest HEL. The easiest basal slip was activated by shock loading along the inclined, off-axis direction and is associated with smallest HEL value. For all orientations, we observed elastic precursor decay and growth of the HEL values with increasing temperature. However, for the c-orientation the growth is caused by decrease of elastic constants and not with an increase of resolved shear stress along the pyramidal slip planes. In the other orientations the resolved shear stresses in slip planes at the HEL increased with temperature. At inclined shock compression we found two plastic shock waves for which the stress behind the first depends on the peak stress associated with the second plastic wave. The crystals demonstrate the largest spall strength at shock loading along the a-axis and smallest one at shock loading in off-axis direction.

  17. A numerical scheme for ionizing shock waves

    SciTech Connect

    Aslan, Necdet . E-mail: naslan@yeditepe.edu.tr; Mond, Michael

    2005-12-10

    A two-dimensional (2D) visual computer code to solve the steady state (SS) or transient shock problems including partially ionizing plasma is presented. Since the flows considered are hypersonic and the resulting temperatures are high, the plasma is partially ionized. Hence the plasma constituents are electrons, ions and neutral atoms. It is assumed that all the above species are in thermal equilibrium, namely, that they all have the same temperature. The ionization degree is calculated from Saha equation as a function of electron density and pressure by means of a nonlinear Newton type root finding algorithms. The code utilizes a wave model and numerical fluctuation distribution (FD) scheme that runs on structured or unstructured triangular meshes. This scheme is based on evaluating the mesh averaged fluctuations arising from a number of waves and distributing them to the nodes of these meshes in an upwind manner. The physical properties (directions, strengths, etc.) of these wave patterns are obtained by a new wave model: ION-A developed from the eigen-system of the flux Jacobian matrices. Since the equation of state (EOS) which is used to close up the conservation laws includes electronic effects, it is a nonlinear function and it must be inverted by iterations to determine the ionization degree as a function of density and temperature. For the time advancement, the scheme utilizes a multi-stage Runge-Kutta (RK) algorithm with time steps carefully evaluated from the maximum possible propagation speed in the solution domain. The code runs interactively with the user and allows to create different meshes to use different initial and boundary conditions and to see changes of desired physical quantities in the form of color and vector graphics. The details of the visual properties of the code has been published before (see [N. Aslan, A visual fluctuation splitting scheme for magneto-hydrodynamics with a new sonic fix and Euler limit, J. Comput. Phys. 197 (2004) 1

  18. IPShocks: Database of Interplanetary Shock Waves

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. Data compression for the Cassini radio and plasma wave instrument

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Gurnett, D. A.; Kirchner, D. L.; Kurth, W. S.; Woolliscroft, L. J. C.

    1993-01-01

    The Cassini Radio and Plasma Wave Science experiment will employ data compression to make effective use of the available data telemetry bandwidth. Some compression will be achieved by use of a lossless data compression chip and some by software in a dedicated 80C85 processor. A description of the instrument and data compression system are included in this report. Also, the selection of data compression systems and acceptability of data degradation is addressed.

  20. One-Dimensional Shock Wave Formation by an Accelerating Piston. Ph.D. Thesis - Ohio State Univ.

    NASA Technical Reports Server (NTRS)

    Mann, M. J.

    1970-01-01

    The formation of a shock wave by a solid accelerating piston was studied. A theoretical solution using the method of characteristics for a perfect gas showed that a complex wave system exists, and that the compressed gas can have large gradients in temperature, density and entropy. Experiments were performed with a piston tube where piston speed, shock speed and pressure were measured. The comparison of theory and experiment was good.

  1. The mechanism of shock wave treatment in bone healing

    NASA Astrophysics Data System (ADS)

    Wang, Ching-Jen

    2005-04-01

    The purpose of this study was to investigate the biological mechanism of shock wave treatment in bone healing in rabbits. A closed fracture of the right femur was created with a three-point bend method and the fracture was stabilized with an intra-medullary pin. Shock waves were applied one week after the fracture. Twenty-four New Zealand white rabbits were randomly divided into 3 groups. Group 1 (the control) received no shock waves; group 2 received low-energy and group 3 high-energy shock waves. The animals were sacrificed at 24 weeks, and a 5-cm segment of the femur bone including the callus was harvested. The specimens were studied with histomorphological examination, biomechanical analysis and immunohistochemical stains. The results showed that high-energy shock waves improved bone healing with significant increases in cortical bone formation and the number neovascularization in histomorphology, better bone strength and bone mass in biomechanics, and increased expressions of angiogenic growth markers including BMP-2, eNOS, VEGF and PCNA than the control and low-energy shock wave groups. The effect of shock wave treatment appears to be dose-dependent. In conclusion, high-energy shock waves promote bone healing associated with ingrowth of neovascularization and increased expressions of angiogenic growth factors.

  2. Shock Waves for Possible Application in Regenerative Medicine

    NASA Astrophysics Data System (ADS)

    Hosseini, S. H. R.; Nejad, S. Moosavi; Akiyama, H.

    The paper reports experimental study of underwater shock waves effects in modification and possible control of embryonic stem cell differentiation and proliferation. The study is motivated by its application in regenerativemedicine. Underwater shock waves have been of interest for various scientific, industrial, and medical applications.

  3. Dispersive shock waves in nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Smyth, Noel F.

    2016-10-01

    The propagation of coherent light with an initial step intensity profile in a nematic liquid crystal is studied using modulation theory. The propagation of light in a nematic liquid crystal is governed by a coupled system consisting of a nonlinear Schrödinger equation for the light beam and an elliptic equation for the medium response. In general, the intensity step breaks up into a dispersive shock wave, or undular bore, and an expansion fan. In the experimental parameter regime for which the nematic response is highly nonlocal, this nematic bore is found to differ substantially from the standard defocusing nonlinear Schrödinger equation structure due to the effect of the nonlocality of the nematic medium. It is found that the undular bore is of Korteweg-de Vries equation-type, consisting of bright waves, rather than of nonlinear Schrödinger equation-type, consisting of dark waves. In addition, ahead of this Korteweg-de Vries bore there can be a uniform wavetrain with a short front which brings the solution down to the initial level ahead. It is found that this uniform wavetrain does not exist if the initial jump is below a critical value. Analytical solutions for the various parts of the nematic bore are found, with emphasis on the role of the nonlocality of the nematic medium in shaping this structure. Excellent agreement between full numerical solutions of the governing nematicon equations and these analytical solutions is found.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

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

    SciTech Connect

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

    2009-07-01

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

  6. On cylindrically converging shock waves shaped by obstacles

    SciTech Connect

    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.

  7. Optical beam distortions induced by a shock wave.

    PubMed

    Banakh, V A; Sukharev, A A; Falits, A V

    2015-03-10

    The mean intensity and the displacement from the initially given propagation direction of the optical beam passed through the shock wave have been calculated. It has been shown that the spatial inhomogeneity of the refractive index of air caused by the shock wave arising in supersonic flow flowing a conical body can cause the focusing of the beam and strong anisotropic distortions of the intensity distribution in its cross section. The angular displacement of the optical beam from the initially given propagation direction owing to the shock wave depends only on the height above the Earth's surface at which the shock wave is formed. As the height increases, the influence of the shock wave on the optical beam propagating through it decreases.

  8. Shock wave convergence in water with parabolic wall boundaries

    SciTech Connect

    Yanuka, D.; Shafer, D.; Krasik, Ya.

    2015-04-28

    The convergence of shock waves in water, where the cross section of the boundaries between which the shock wave propagates is either straight or parabolic, was studied. The shock wave was generated by underwater electrical explosions of planar Cu wire arrays using a high-current generator with a peak output current of ∼45 kA and rise time of ∼80 ns. The boundaries of the walls between which the shock wave propagates were symmetric along the z axis, which is defined by the direction of the exploding wires. It was shown that with walls having a parabolic cross section, the shock waves converge faster and the pressure in the vicinity of the line of convergence, calculated by two-dimensional hydrodynamic simulations coupled with the equations of state of water and copper, is also larger.

  9. SHOCK-WAVE THERAPY APPLICATION IN CLINICAL PRACTICE (REVIEW).

    PubMed

    Sheveleva, N; Minbayeva, L; Belyayeva, Y

    2016-03-01

    The article presents literature review on the use of extracorporeal shock-wave therapy in physiotherapeutic practice. The basic mechanisms of shock waves influence on the organism are spotlighted. Studies proving high efficacy of the method in treatment of wide variety of inflammatory diseases and traumatic genesis are presented. The data on comparative assessment of shock-wave therapy efficacy, and results of researches on possibility of extracorporeal shock-wave therapy effect potentiating in combination with other therapeutic methods are reflected. Recent years, the range of indications for shock-wave therapy application had been significantly widened. However, further study of the method is still relevant because mechanisms of action of the factor are studied insufficiently; methods of therapy parameters selection (energy flux density, number of pulses per treatment, duration of a course) are either advisory or empirical.

  10. Shock wave relations in lunar ash flow

    NASA Technical Reports Server (NTRS)

    Pai, S. I.; Hsieh, T.

    1975-01-01

    A detailed analysis of steady normal shock waves in a layer of lunar ash by the theory of two phase flow of a mixture of a gas and small solid particles is presented. New terms of pressure gradient and virtual mass forces in the particle momentum equation and the particle kinetic energy and work done in the particle energy equation are included in the fundamental equations and their influences are investigated. The flow variables as functions of the free stream Mach number, initial particle volume fraction and the density ratio G are presented. The thickness of the relaxation zone is found to increase with decreasing initial particle volume fraction and almost independent of G for any given values of free stream Mach number. A new empirical relation of the drag coefficient for the spherical particles in the mixture is proposed to fit experimental data.

  11. Dispersive shock wave interactions and asymptotics.

    PubMed

    Ablowitz, Mark J; Baldwin, Douglas E

    2013-02-01

    Dispersive shock waves (DSWs) are physically important phenomena that occur in systems dominated by weak dispersion and weak nonlinearity. The Korteweg-de Vries (KdV) equation is the universal model for systems with weak dispersion and weak, quadratic nonlinearity. Here we show that the long-time-asymptotic solution of the KdV equation for general, steplike data is a single-phase DSW; this DSW is the "largest" possible DSW based on the boundary data. We find this asymptotic solution using the inverse scattering transform and matched-asymptotic expansions. So while multistep data evolve to have multiphase dynamics at intermediate times, these interacting DSWs eventually merge to form a single-phase DSW at large time. PMID:23496590

  12. Shock wave compacted, melt infiltrated ceramics

    SciTech Connect

    Stuivinga, M.; Carton, E. P.

    1998-07-10

    Using shock wave compaction followed by melt infiltration with aluminum, B{sub 4}C-Al and TiB{sub 2}-Al composites have been fabricated. The composites are fully dense and crack-free. They have a high (80-85 vol.%) ceramic content, which gives them good mechanical properties. Due to the infiltration with aluminum, they also have rather good conductive properties. This makes it possible to machine them using spark erosion, in order to obtain complex articles such as nozzles and dies. They are lightweight, an advantage for application in armor and fast turning spindles. In the present article, scanning electron micrographs of the fracture surfaces will be shown and some material properties will be presented.

  13. Shock compression experiment of forsterite: pulverization and frictional melting in a shear regime

    NASA Astrophysics Data System (ADS)

    Obata, M.; Mashimo, T.; Ando, J. I.; Chen, L.; Yamamoto, T.

    2015-12-01

    Seismic waves may be generated by a rapid slip accompanied by a rapid stress drop at or near the running rapture tip. To study the detailed processes and the material change occurring at the fracture tip, we performed a series of shock compression experiments using a keyed powder gun and a single crystal of forsterite Fo 94. A olivine disket (diameter 12 mm, thickness 3 mm, perpendicular to the c-axis) is mounted in a steel capsule of diameter 2 cm and length 4 cm. Flyer speed was 1.5 km/s; applied pressure was ca. 31 GPa; and shock wave velocity and particle velocity were ca. 7 km/s and ca. 1 km/s, respectively. After the shock experiment the sample was recovered and examined by optical microscopy, SEM and TEM. Although the olivine largely remained to be a single crystal, it shows wavy extinctions and many parallel shear planes diagonal to the compression axis. Shear planes (i.e., fault) are macroscopically sharp and show displacement of up to 0.5 mm. The TEM observation of the fault wall revealed that the wall has a zonal structure. Well inside the wall are developed densely spaced and tangles [001] screw dislocations. Outer 2-5 micron zone is polycrystalline olivine of grain size 200-300 nm. The outermost zone is an aggregate of semi-rounded small olivine particles (ca. 200 nanometers) mounted in a matrix of glass of olivine composition. It is inferred from these microstructures that polygonization and pulverization predated the melting. Such pulverization is possible at a running fracture tip, where stress and strain rate are the highest. Moreover, very thin injection veins (ca. 50-350 nanometer thick) filled with olivine glasses locally occurred in the fault wall, suggesting fracturing and crack opening had occurred while olivine melt was present. The fracturing was probably propelled by the rapid sweep of shock waves running through the crystal. Melting probably took place by a rapid collision and frictions among the olivine nanoparticles. It is suggested

  14. Schlieren imaging of loud sounds and weak shock waves in air near the limit of visibility

    NASA Astrophysics Data System (ADS)

    Hargather, Michael John; Settles, Gary S.; Madalis, Matthew J.

    2010-02-01

    A large schlieren system with exceptional sensitivity and a high-speed digital camera are used to visualize loud sounds and a variety of common phenomena that produce weak shock waves in the atmosphere. Frame rates varied from 10,000 to 30,000 frames/s with microsecond frame exposures. Sound waves become visible to this instrumentation at frequencies above 10 kHz and sound pressure levels in the 110 dB (6.3 Pa) range and above. The density gradient produced by a weak shock wave is examined and found to depend upon the profile and thickness of the shock as well as the density difference across it. Schlieren visualizations of weak shock waves from common phenomena include loud trumpet notes, various impact phenomena that compress a bubble of air, bursting a toy balloon, popping a champagne cork, snapping a wooden stick, and snapping a wet towel. The balloon burst, snapping a ruler on a table, and snapping the towel and a leather belt all produced readily visible shock-wave phenomena. In contrast, clapping the hands, snapping the stick, and the champagne cork all produced wave trains that were near the weak limit of visibility. Overall, with sensitive optics and a modern high-speed camera, many nonlinear acoustic phenomena in the air can be observed and studied.

  15. Augmented shock wave fracture/severance of materials

    NASA Technical Reports Server (NTRS)

    Schimmel, Morry L. (Inventor); Bement, Laurence J. (Inventor)

    1995-01-01

    The present invention related generally to severing materials, and more particularly to severing or weakening materials through explosively induced, augmented shock waves. Explosive cords are placed in grooves on the upper surface of the material to be severed or weakened. The explosive cords are initiated simultaneously to introduce explosive shock waves into the material. These shock waves progress toward the centerline between the explosive cords and the lower surface of the material. Intersecting and reflected waves produce a rarefaction zone on the centerline to fail the material in tension. A groove may also be cut in the lower surface of the material to aid in severing or weakening the material.

  16. Laser-induced shock waves effects in materials

    SciTech Connect

    Dingus, R.S.; Shafer, B.P.

    1990-01-01

    A review of the effects of pressure pulses on materials is presented with an orientation toward laser-induced shock wave effects in biological tissue. The behavior is first discussed for small amplitudes, namely sound waves, since many important features in this region are also applicable at large amplitudes. The generation of pressure pulses by lasers is discussed along with amplitudes. The origin and characteristic properties of shock waves are discussed along with the different types of effects they can produce. The hydrodynamic code techniques required for shock wave calculations are discussed along with the necessary empirical data base and methods for generating that data base. 7 refs., 15 figs.

  17. Photoacoustic shock wave emission and cavitation from structured optical fiber tips

    NASA Astrophysics Data System (ADS)

    Mohammadzadeh, Milad; Gonzalez Avila, Silvestre Roberto; Wan, Yin Chi; Wang, Xincai; Zheng, Hongyu; Ohl, Claus-Dieter

    2015-11-01

    Fiber optics are used in medicine to deliver laser pulses for microsurgery. Upon absorption of a high-power laser pulse, a thermoelastic wave is emitted from the fiber tip. If a flat cleaved fiber is used, the photoacoustic field comprises a planar compressive shock wave and a tensile diffraction wave from the tip edge. Here we demonstrate that by modifying the geometry of a fiber tip, multiple shock waves can be generated from a single laser pulse. Flat cleaved fibers generate tension only along the fiber axis and with one compression-tension cycle from a laser pulse; however, structured fiber tips cause significant tension both along and off-axis, and generate multiple pressure cycles from a single laser pulse. Fast flash photography reveals that diffraction waves from the edges of the tip structures overlap and generate enough tension to form cavitation clouds. We numerically solve the linear wave equation to model the acoustic transients of structured fiber tips and achieve good agreement with pressure measurements from a fiber optic hydrophone. Multiple shock wave emission from a single laser pulse introduces structured fiber tips as a candidate to deliver histotripsy effects via a surgical catheter for micro-scale ablation of soft tissue.

  18. The influence of incident shock Mach number on radial incident shock wave focusing

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Tan, Sheng; He, Liming; Rong, Kang; Zhang, Qiang; Zhu, Xiaobin

    2016-04-01

    Experiments and numerical simulations were carried out to investigate radial incident shock focusing on a test section where the planar incident shock wave was divided into two identical ones. A conventional shock tube was used to generate the planar shock. Incident shock Mach number of 1.51, 1.84 and 2.18 were tested. CCD camera was used to obtain the schlieren photos of the flow field. Third-order, three step strong-stability-preserving (SSP) Runge-Kutta method, third-order weighed essential non-oscillation (WENO) scheme and adaptive mesh refinement (AMR) algorithm were adopted to simulate the complicated flow fields characterized by shock wave interaction. Good agreement between experimental and numerical results was observed. Complex shock wave configurations and interactions (such as shock reflection, shock-vortex interaction and shock focusing) were observed in both the experiments and numerical results. Some new features were observed and discussed. The differences of structure of flow field and the variation trends of pressure were compared and analyzed under the condition of different Mach numbers while shock wave focusing.

  19. Cytoplasmic molecular delivery with shock waves: importance of impulse.

    PubMed Central

    Kodama, T; Hamblin, M R; Doukas, A G

    2000-01-01

    Cell permeabilization using shock waves may be a way of introducing macromolecules and small polar molecules into the cytoplasm, and may have applications in gene therapy and anticancer drug delivery. The pressure profile of a shock wave indicates its energy content, and shock-wave propagation in tissue is associated with cellular displacement, leading to the development of cell deformation. In the present study, three different shock-wave sources were investigated; argon fluoride excimer laser, ruby laser, and shock tube. The duration of the pressure pulse of the shock tube was 100 times longer than the lasers. The uptake of two fluorophores, calcein (molecular weight: 622) and fluorescein isothiocyanate-dextran (molecular weight: 71,600), into HL-60 human promyelocytic leukemia cells was investigated. The intracellular fluorescence was measured by a spectrofluorometer, and the cells were examined by confocal fluorescence microscopy. A single shock wave generated by the shock tube delivered both fluorophores into approximately 50% of the cells (p < 0.01), whereas shock waves from the lasers did not. The cell survival fraction was >0.95. Confocal microscopy showed that, in the case of calcein, there was a uniform fluorescence throughout the cell, whereas, in the case of FITC-dextran, the fluorescence was sometimes in the nucleus and at other times not. We conclude that the impulse of the shock wave (i.e., the pressure integrated over time), rather than the peak pressure, was a dominant factor for causing fluorophore uptake into living cells, and that shock waves might have changed the permeability of the nuclear membrane and transferred molecules directly into the nucleus. PMID:11023888

  20. Shock Wave-Induced Damage of a Protein by Void Collapse.

    PubMed

    Lau, Edmond Y; Berkowitz, Max L; Schwegler, Eric

    2016-01-01

    In this study, we report on a series of molecular dynamics simulations that were used to examine the effects of shock waves on a membrane-bound ion channel. A planar shock wave was found to compress the ion channel upon impact, but the protein geometry resembles the crystal structure as soon as the solvent density begins to dissipate. When a void was placed in close proximity to the membrane, the shock wave proved to be more destructive to the protein due to formation of a nanojet that results from the asymmetric collapse of the void. The nanojet was able to cause significant structural changes to the protein even at low piston velocities that are not able to directly cause poration of the membrane.

  1. Review of methods to attenuate shock/blast waves

    NASA Astrophysics Data System (ADS)

    Igra, O.; Falcovitz, J.; Houas, L.; Jourdan, G.

    2013-04-01

    Quick and reliable shock wave attenuation is the goal of every protection facility and therefore it is not surprising that achieving this has drawn much attention during the past hundred years. Different options have been suggested; their usefulness varying from a reasonable protection to the opposite, a shock enhancement. An example for a suggestion for shock mitigation that turned out to be an enhancement of the impinging shock wave was the idea to cover a protected object with a foam layer. While the pressure behind the reflected shock wave from the foam frontal surface was smaller than that recorded in a similar reflection from a rigid wall [25], the pressure on the “protected” surface, attached to the foam's rear-surface, was significantly higher than that recorded in a similar reflection from a bare, rigid wall [11]. In protecting humans and installations from destructive shock and/or blast waves the prime goal is to reduce the wave amplitude and the rate of pressure increase across the wave front. Both measures result in reducing the wave harmful effects. During the past six decades several approaches for achieving the desired protection have been offered in the open literature. We point out in this review that while some of the suggestions offered are practical, others are impractical. In our discussion we focus on recent schemes for shock/blast wave attenuation, characterized by the availability of reliable measurements (notably pressure and optical diagnostics) as well as high-resolution numerical simulations.

  2. August Toepler — The first who visualized shock waves

    NASA Astrophysics Data System (ADS)

    Krehl, P.; Engemann, S.

    1995-06-01

    The scientific investigation of the nature of shock waves started 130 years ago with the advent of the schlieren method which was developed in the period 1859 1864 by August Toepler. At the very beginning applied to the visualization of heat and flow phenomena, he immediately turned to air shock waves generated by electric sparks, and subjectively studied the propagation, reflection and refraction of shock waves. His new delay circuit in the microsecond time regime for the first time made it possible to vary electrically the delay time between a spark generating a shock wave and a second spark acting as a flash light source in his chlieren setup. In 1870 Toepler, together with Boltzmann, applied Jamin's interferometric refractometer and extended the visualization to very weak sound waves at the threshold of hearing. Toepler's pioneering schlieren method stimulated Ernst Mach and his team to objectively investigate the nature of shock waves: they improved Toepler's time delay circuit; continued the study on the reflection of shock waves; introduced shadowgraphy as a modification of the schlieren method; photographed the propagation of shock waves generated by an electric spark and by supersonic projectiles, and improved interferometry. Based on a large number of original documents the paper illuminates the concomitant circumstances of the invention of the schlieren method and its first applications by others.

  3. Optical Radiation from Shock-Compressed Materials. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Svendsen, Robert F., Jr.

    1987-01-01

    Recent observations of shock-induced radiation from oxides, silicates, and metals of geophysical interest constrain the shock-compressed temperature of these materials. The relationships between the temperature inferred from the observed radiation and the temperature of the shock-compressed film or foil and/or window were investigated. Changes of the temperature field in each target component away from that of their respective shock-compressed states occur because of: shock-impedance mismatch between target components; thermal mismatch between target components; surface roughness at target interfaces; and conduction within and between target components. In particular, conduction may affect the temperature of the film/foil window interface on the time scale of the experiments, and so control the intensity and history of the dominant thermal radiation sources in the target. This type of model was used to interpret the radiation emitted by a variety of shock-compressed materials and interfaces.

  4. Electrical Properties of PZT 52/48 under Ramp Wave Compression

    NASA Astrophysics Data System (ADS)

    Jackson, D. P.; Montgomery, S. T.; Wise, J. L.; Clark, G. E.; Duckett, E. B.

    2011-06-01

    Measurements of electrical responses from ferroelectric ceramic disks under shock wave compression where the directions of wave propagation and remanent polarization are aligned have been conducted on a variety of lead zirconate titanate compositions. Analysis of the electrical responses is complicated by the electric conditions in the disk, tilt in the planar shock, and the variety of material compositions examined. A review of previous measurements on PZT 65/35 ceramic, at stress levels not expected to drive the material into the paraelectric phase and where charge is restricted from flowing from the disk, indicates that above a certain stress threshold the available charge release is complete and the inverse permittivity in the shock compressed ceramic increases linearly with compressive stress. An electrical response model, based on the these observations, is used to explain the electric output from experiments on PZT 52/48 disks under ramp wave compression when the disk faces are connected through a small, or very large, resistive load. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  5. Theoretical study of plasma effect on a conical shock wave

    SciTech Connect

    Kuo, S.P.; Kuo, Steven S.

    2006-03-15

    Experiments conducted previously in a Mach 2.5 wind tunnel showed that localized plasma generated by an on-board 60 Hz electric discharge in front of a 60 deg. cone-shaped model considerably increases the shock angle of the attached shock generated by the cone model. Based on the measured power and cycle energy of the electric discharge, the estimated peak and average temperature enhancements were too low to justify the heating effect as a possible cause of the observed shock wave modification. In this work, a theory also using a cone model as the shock wave generator is presented to explain the observed plasma effect on the shock wave. Through electron-neutral elastic collisions and ion-neutral charge transfer collisions, plasma generated in front of the baseline shock front can deflect the incoming flow before it reaches the cone model; such a flow deflection modifies the structure of the shock wave generated by the cone model from a conic shape to a slightly curved one. The shock remains to be attached to the tip of the cone; however, the shock front moves upstream to increase the shock angle, consistent with the experimental results.

  6. Interaction of Ion-Concentration Shock Waves in Microfluidics

    NASA Astrophysics Data System (ADS)

    Bahga, Supreet S.; Chambers, Robert D.; Santiago, Juan G.

    2011-11-01

    Electrophoresis based separation techniques, such as capillary electrophoresis and isotachophoresis (ITP), are routinely used in microfluidics to separate ionic species from complex mixtures. Nonlinearities in these electrophoretic processes can result in formation of shock and rarefaction waves. We here focus on shock waves which form in ITP between regions of high and low mobility ions. Depending on the charge of ions, these shocks can propagate either towards anode or cathode, and may interact with each other. We here demonstrate simultaneous anionic and cationic ITP process, in which shock waves approach each other and then interact. Using simulations and experimental visualizations, we show that the interaction of these shock waves can modify the electrophoretic conditions and result in formation of new shock and rarefaction waves. We show two applications where we use shock interaction to couple different electrophoretic processes: (i) where we first preconcentrate DNA fragments in anionic ITP and then use shock interaction to initiate DNA separation, and (ii) where we use shock interaction to elongate ITP zones for higher sensitivity.

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

    NASA Astrophysics Data System (ADS)

    Ryu, Dongsu

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

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

    NASA Astrophysics Data System (ADS)

    Ryu, Dongsu

    2008-04-01

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

  9. Weak-wave analysis of shock interaction with a slipstream

    NASA Technical Reports Server (NTRS)

    Barger, Raymond L.

    1988-01-01

    A weak wave analysis of shock interaction with a slipstream is presented. The theory is compared to that for the acoustic case and to the exact nonlinear analysis. Sample calculations indicate that the weak wave theory yields a good approximation to the exact solution when the shock waves are sufficiently weak that the associated entropy increase is negligible. A qualitative discussion of the case of counterflowing streams is also included.

  10. Simplified laser-driven flyer plates for shock compression science

    NASA Astrophysics Data System (ADS)

    Brown, Kathryn E.; Shaw, William L.; Zheng, Xianxu; Dlott, Dana D.

    2012-10-01

    We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s-1 and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.

  11. Simplified laser-driven flyer plates for shock compression science.

    PubMed

    Brown, Kathryn E; Shaw, William L; Zheng, Xianxu; Dlott, Dana D

    2012-10-01

    We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s(-1) and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.

  12. Simplified laser-driven flyer plates for shock compression science

    SciTech Connect

    Brown, Kathryn E.; Shaw, William L.; Zheng Xianxu; Dlott, Dana D.

    2012-10-15

    We describe a simplified system of laser-driven flyer plates for shock compression science and shock spectroscopy. We used commercially available one-box Nd:YAG lasers and beam homogenization solutions to create two launch systems, one based on a smaller (400 mJ) YAG laser and an inexpensive diffusive optic, and one based on a larger (2500 mJ) laser and a diffractive beam homogenizer. The flyer launch, flight, and impact processes were characterized by an 8 GHz fiberoptic photon Doppler velocimeter. We investigated effects of different substrates, adhesives, absorbers, ablative layers, and punching out disks from continuous foils versus fabricating individual foil disks, and found that a simple metal foil epoxied to a glass window was satisfactory in almost all cases. Our simplified system launched flyer plates with velocities up to 4.5 km s{sup -1} and kinetic energies up to 250 mJ that can drive sustained steady shocks for up to 25 ns. The factor that limits these velocities and energies is the laser fluence that can be transmitted through the glass substrate to the flyer surface without optical damage. Methods to increase this transmission are discussed. Reproducible flyer launches were demonstrated with velocity variations of 0.06% and impact time variations of 1 ns. The usefulness of this flyer plate system is demonstrated by Hugoniot equation of state measurements of a polymer film, emission spectroscopy of a dye embedded in the polymer, and impact initiation and emission spectroscopy of a reactive material consisting of nanoscopic fuel and oxidizer particles.

  13. Medical applications and bioeffects of extracorporeal shock waves

    NASA Astrophysics Data System (ADS)

    Delius, M.

    1994-09-01

    Lithotripter shock waves are pressure pulses of microsecond duration with peak pressures of 35 120 MPa followed by a tensile wave. They are an established treatment modality for kidney and gallstone disease. Further applications are pancreatic and salivary stones, as well as delayed fracture healing. The latter are either on their way to become established treatments or are currently under investigation. Shock waves generate tissue damage as a side effect which has been extensively investigated in the kidney, the liver, and the gallbladder. The primary adverse effects are local destruction of blood vessels, bleedings, and formation of blood clots in vessels. Investigations on the mechanism of shock wave action revealed that lithotripters generate cavitation both in vitro and in vivo. An increase in tissue damage at higher pulse administration rates, and also at shock wave application with concomitant gas bubble injection suggested that cavitation is a major mechanism of tissue damage. Disturbances of the heart rhythm and excitation of nerves are further biological effects of shock waves; both are probably also mediated by cavitation. On the cellular level, shock waves induce damage to cell organelles; its extent is related to their energy density. They also cause a transient increase in membrane permeability which does not lead to cell death. Administered either alone or in combination with drugs, shock waves have been shown to delay the growth of small animal tumors and even induce tumor remissions. While the role of cavitation in biological effects is widely accepted, the mechanism of stone fragmentation by shock waves is still controversial. Cavitation is detected around the stone and hyperbaric pressure suppresses fragmentation; yet major cracks are formed early before cavitation bubble collapse is observed. The latter has been regarded as evidence for a direct shock wave effect.

  14. Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed

    NASA Technical Reports Server (NTRS)

    Ackeret, J.; Feldmann, F.; Rott, N.

    1947-01-01

    The mutual influences of compression shocks and friction boundary layers were investigated by means of high speed wind tunnels.Schlieren optics provided a clear picture of the flow phenomena and were used for determining the location of the compression shocks, measurement of shock angles, and also for Mach angles. Pressure measurement and humidity measurements were also taken into consideration.Results along with a mathematical model are described.

  15. Microstructure and Mechanical Properties After Shock Wave Loading of Cast CrMnNi TRIP Steel

    NASA Astrophysics Data System (ADS)

    Eckner, Ralf; Krüger, L.; Ullrich, C.; Rafaja, D.; Schlothauer, T.; Heide, G.

    2016-10-01

    The mechanical response of shock wave-prestrained high-alloy Cr16-Mn7-Ni6 TRIP steel was investigated under compressive and tensile loading at room temperature. Previous shock wave loading was carried out using a flyer-plate assembly with different amounts of explosives in order to achieve shock pressures of 0.3, 0.6, 0.9, and 1.2 Mbar. A significant increase in hardness and strength was observed as compared with the initial as-cast condition. In contrast, a slight decrease in strain hardening rates was measured together with a decrease in fracture elongation in the tensile test. Microstructural analyses of the shock-loaded samples were performed by light optical and scanning electron microscopy. The microstructure revealed a high density of deformation bands consisting of separated stacking faults, ɛ-martensite, or twins. Significant amounts of deformation-induced α'-martensite were only present at the highest shock pressure of 1.2 Mbar. The thickness of the deformation bands and the number of martensite nuclei at their intersections increased with increasing shock pressure. In all shock-loaded specimens, pronounced phase transformation occurred during subsequent mechanical testing. Consequently, the amount of the deformation-induced α'-martensite in the shock-loaded specimens was higher than in the unshocked as-cast samples.

  16. Molecular dynamics simulations of shock waves in hydroxyl-terminated polybutadiene melts: mechanical and structural responses.

    PubMed

    Fröhlich, Markus G; Sewell, Thomas D; Thompson, Donald L

    2014-01-14

    The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s(-1), yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structural properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ∼0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude. PMID:24437906

  17. Molecular dynamics simulations of shock waves in hydroxyl-terminated polybutadiene melts: Mechanical and structural responses

    NASA Astrophysics Data System (ADS)

    Fröhlich, Markus G.; Sewell, Thomas D.; Thompson, Donald L.

    2014-01-01

    The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s-1, yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structural properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ˜0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude.

  18. Molecular dynamics simulations of shock waves in hydroxyl-terminated polybutadiene melts: Mechanical and structural responses

    SciTech Connect

    Fröhlich, Markus G. E-mail: ThompsonDon@missouri.edu; Sewell, Thomas D. Thompson, Donald L. E-mail: ThompsonDon@missouri.edu

    2014-01-14

    The mechanical and structural responses of hydroxyl-terminated cis-1,4-polybutadiene melts to shock waves were investigated by means of all-atom non-reactive molecular dynamics simulations. The simulations were performed using the OPLS-AA force field but with the standard 12-6 Lennard-Jones potential replaced by the Buckingham exponential-6 potential to better represent the interactions at high compression. Monodisperse systems containing 64, 128, and 256 backbone carbon atoms were studied. Supported shock waves were generated by impacting the samples onto stationary pistons at impact velocities of 1.0, 1.5, 2.0, and 2.5 km s{sup −1}, yielding shock pressures between approximately 2.8 GPa and 12.5 GPa. Single-molecule structural properties (squared radii of gyration, asphericity parameters, and orientational order parameters) and mechanical properties (density, shock pressure, shock temperature, and shear stress) were analyzed using a geometric binning scheme to obtain spatio-temporal resolution in the reference frame centered on the shock front. Our results indicate that while shear stress behind the shock front is relieved on a ∼0.5 ps time scale, a shock-induced transition to a glass-like state occurs with a concomitant increase of structural relaxation times by several orders of magnitude.

  19. Microstructure and Mechanical Properties After Shock Wave Loading of Cast CrMnNi TRIP Steel

    NASA Astrophysics Data System (ADS)

    Eckner, Ralf; Krüger, L.; Ullrich, C.; Rafaja, D.; Schlothauer, T.; Heide, G.

    2016-08-01

    The mechanical response of shock wave-prestrained high-alloy Cr16-Mn7-Ni6 TRIP steel was investigated under compressive and tensile loading at room temperature. Previous shock wave loading was carried out using a flyer-plate assembly with different amounts of explosives in order to achieve shock pressures of 0.3, 0.6, 0.9, and 1.2 Mbar. A significant increase in hardness and strength was observed as compared with the initial as-cast condition. In contrast, a slight decrease in strain hardening rates was measured together with a decrease in fracture elongation in the tensile test. Microstructural analyses of the shock-loaded samples were performed by light optical and scanning electron microscopy. The microstructure revealed a high density of deformation bands consisting of separated stacking faults, ɛ-martensite, or twins. Significant amounts of deformation-induced α'-martensite were only present at the highest shock pressure of 1.2 Mbar. The thickness of the deformation bands and the number of martensite nuclei at their intersections increased with increasing shock pressure. In all shock-loaded specimens, pronounced phase transformation occurred during subsequent mechanical testing. Consequently, the amount of the deformation-induced α'-martensite in the shock-loaded specimens was higher than in the unshocked as-cast samples.

  20. The physical nature of weak shock wave reflection

    NASA Astrophysics Data System (ADS)

    Skews, Beric W.; Ashworth, Jason T.

    2005-10-01

    For weak shock waves and small wedge angles the application of three-shock (von Neumann) theory gives no physically realistic solutions and yet experiments clearly show a pattern of reflection of three shocks meeting at a triple point. This disagreement is referred to as the von Neumann paradox, and the reflection pattern as von Neumann reflection (vNR). Some recent numerical computations have indicated the existence of an expansion wave immediately behind the reflected wave as originally suggested by Guderley over fifty years ago. Furthermore, a recent solution of the inviscid transonic equations has indicated the possible existence of a very small, multi-wave structure immediately behind the three-shock confluence. A special shock tube has been constructed which allows Mach stem lengths to be obtained which are more than an order of magnitude larger than those obtainable in conventional shock tubes. Schlieren photographs do indeed show a structure consisting of an expansion wave followed by a small shock situated behind the confluence point, with some indication of smaller scale structures in some tests. This indicates that some of the earlier models of vNR, in the parameter space tested, are incorrect. The size of the region influenced by this small wave system is about 2% of the Mach stem length and it is therefore not surprising that it has not been detected before in conventional shock tube facilities.

  1. The Observational Consequences of Proton-Generated Waves at Shocks

    NASA Technical Reports Server (NTRS)

    Reames, Donald V.

    2000-01-01

    In the largest solar energetic particle (SEP) events, acceleration takes place at shock waves driven out from the Sun by fast coronal mass ejections. Protons streaming away from strong shocks generate Alfven waves that trap particles in the acceleration region, limiting outflowing intensities but increasing the efficiency of acceleration to higher energies. Early in the events, with the shock still near the Sun, intensities at 1 AU are bounded and spectra are flattened at low energies. Elements with different charge-to-mass ratios, Q/A, differentially probe the wave spectra near shocks, producing abundance ratios that vary in space and time. An initial rise in He/H, while Fe/O declines, is a typical symptom of the non-Kolmogorov wave spectra in the largest events. Strong wave generation can cause cross-field scattering near the shock and unusually rapid reduction in anisotropies even far from the shock. At the highest energies, shock spectra steepen to form a "knee." For protons, this spectral knee can vary from approx. 10 MeV to approx. 1 GeV depending on shock conditions for wave growth. In one case, the location of the knee scales approximately as Q/A in the energy/nucleon spectra of other species.

  2. Dynamics of concerted bubble cluster collapse in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Pishchalnikov, Yuri A.; McAteer, James A.; Evan, Andrew P.; Sapozhnikov, Oleg A.; Cleveland, Robin O.; Colonius, Tim; Bailey, Michael R.; Crum, Lawrence A.

    2003-10-01

    Cavitation bubble cluster collapse at the surface of artificial kidney stones during shock wave lithotripsy was investigated in vitro by means of multiframe high-speed photography, passive cavitation detection (PCD), and pressure waveform measurements using a fiber-optic probe hydrophone (FOPH). It was observed that after the passage of the lithotripter shock pulse the stone was covered by numerous individual bubbles. During their growth phase the bubbles coalesced into bubble clusters, with the biggest cluster at the proximal face of the stone. High-speed camera images suggested that cluster collapse started at the periphery and ended with a violent collapse in a small region in the center of the surface of the stone. Shadowgraphy resolved numerous secondary shock waves emitted during this focused collapse. Shock wave emission during cluster collapse was confirmed by PCD. Measurement with the FOPH showed that these shock waves were typically of short duration (0.2 μs). The majority of the shock waves emanating from cluster collapse were low amplitude but some shock waves registered amplitudes on the order of the incident shock pulse (tens of MPa). [Work supported by NIH DK43881, DK55674.

  3. Fiber optic techniques for measuring various properties of shock waves

    NASA Astrophysics Data System (ADS)

    Prinse, Wim C.; van Esveld, Rene; Oostdam, Rene; van Rooijen, Murk; Bouma, Richard

    1999-06-01

    For the past years we have developed several optical techniques to measure properties of shock waves. The fiber optic probe (FOP) is developed to measure the shock-wave velocity and/or the detonation velocity inside an explosive. The space resolution can be as small as 0.5 mm. Single fibers are used as velocity pins, and as devices to measure the flatness of flyers. Arrays of fibers are used to measure the curvature of a shock or detonation front. Also a Fabry-Perot velocity Interferometer System is constructed to measure the velocity of the flyer of an electric gun and the particle velocity in a shock wave. It is possible to combine these two measurements to determine simultaneously the flyer velocity that induces a shock wave in sample and the particle velocity in a window material at the back in a single streak record.

  4. Nonlinear waves and shocks in relativistic two-fluid hydrodynamics

    NASA Astrophysics Data System (ADS)

    Haim, L.; Gedalin, M.; Spitkovsky, A.; Krasnoselskikh, V.; Balikhin, M.

    2012-06-01

    Relativistic shocks are present in a number of objects where violent processes are accompanied by relativistic outflows of plasma. The magnetization parameter σ = B2/4πnmc2 of the ambient medium varies in wide range. Shocks with low σ are expected to substantially enhance the magnetic fields in the shock front. In non-relativistic shocks the magnetic compression is limited by nonlinear effects related to the deceleration of flow. Two-fluid analysis of perpendicular relativistic shocks shows that the nonlinearities are suppressed for σ<<1 and the magnetic field reaches nearly equipartition values when the magnetic energy density is of the order of the ion energy density, Beq2 ~ 4πnmic2γ. A large cross-shock potential eφ/mic2γ0 ~ B2/Beq2 develops across the electron-ion shock front. This potential is responsible for electron energization.

  5. Dynamic Strength and Inelastic Deformation of Ceramics under Shock Wave Loading

    NASA Astrophysics Data System (ADS)

    Feng, R.

    1997-07-01

    Determining the material strength and understanding the inelastic deformation mechanisms of ceramics under plane shock wave compression is important for characterizing their response to rapid impulsive loading. While Hugoniot data and shock wave profiles have been obtained for various ceramics, these data by themselves are insufficient to uniquely determine the material strength and to distinguish between postulated deformation mechanisms. In recent work on a dense ceramic (silicon carbide), we used two independent methods to determine the material strength in the shocked state: longitudinal and lateral stress gauge measurements; and combined compression and shear wave experiments. These data and related 1-D and 2-D computations have provided a complete characterization of the stress state in the shocked SiC. The results show a significant increase in material strength for peak stresses ranging from the HEL to twice the HEL. To consistently interpret this result and the observation of diminishing tensile strength from typical spall experiments on shocked ceramics, we propose an inhomogeneous deformation process involving both micro-plasticity and confined micro-fissures. Recent results from in-situ unloading experiments support this hypothesis.

  6. Fast, non-linear optical-scattering spectroscopy in shock-compressed organic liquids

    SciTech Connect

    Schmidt, S.C.; Moore, D.S.; Schiferl, D.; Shaner, J.W.

    1983-01-01

    Nanosecond stimulated Raman and coherent anti-Stokes Raman scattering spectroscopy have been used to determine molecular vibrational frequency shifts and changes of phase in shock-compressed organic liquids. Results of dynamic experiments are compared to static Raman scattering measurements of samples, compressed and heated in a diamond-anvil cell. Objectives of the experiments are to determine the molecular structure and ultimately the energy transfer mechanisms in shock-compressed condensed phase materials.

  7. Nonideal Plasma Under Exreme Conditions Generated by Intense Shock Waves

    NASA Astrophysics Data System (ADS)

    Fortov, Vladimir

    2004-05-01

    Physical properties of hot dense matter at megabar pressures are the physical basis for astrophysics, planetary physics, energetics, ICF target design, beam-matter interaction, and for many other applications. The new experimental results of pressure ionization investigation of the hot dense matter generated by multiple shock compression of metals, H2, He, noble gases, S, I, fullerene C60, and H2O in the megabar pressure range are presented. High energy plasma states were generated by single and multiple shock compression and adiabatic expansion of initially warm and cryogenic solid, liquid, porous and low-density foams (aerogels) samples. These data in combination with exploding wire conductivity measurements demonstrate an ionization rate increase up to ten orders of magnitude as a result of compression of dense matter. Multiple shock compression of H2, Ar, He, Kr, Ne, Xe, and fullerene C60 in initially gaseous and cryogenic liquid state allows to measure the electrical conductivity, equation of state, and laser beam reflectivity. Thermal and pressure ionization of strongly coupled states of matter is the most prominent effects under the experimental conditions. It was shown that plasma compression strongly deforms the ionization potentials, emission spectra and scattering cross-sections of the neutrals and ions in the strongly coupled matter. Comparison of the data obtained with theoretical models (percolation, Mott transition, Zeeman and Lorenz approach etc.) is presented. In contrast to the plasma compression experiments the multiple shock compression of solid Li, Na, and Ca shows dielectrization of these elements.

  8. Melting and band gap-dynamics of shock-compressed graphite diagnosed by x-ray scattering at the LCLS

    NASA Astrophysics Data System (ADS)

    Zastrau, Ulf; Lee, Hae Ja

    2015-11-01

    The diversity of the electronic properties of carbon makes it of key interest to the material science community; By contrast, at the high pressures typical of planetary and stellar interiors, the behavior of carbon is poorly understood with large uncertainties in the conductivity and even the material phase. Tremendous efforts have been made to measure properties of warm dense matter (WDM) in extreme conditions, e.g. temperatures in excess of 1000 K of temperature and pressures in the Mbar regime. In laboratory experiments, practical issues with gradients in the temperature and density of shock compressed matter have hindered accurate measurement and further from distinguishing theoretical models. Here, we present measurements of melting of graphite upon coalescence of two counter-propagating shocks using combinations of spatially and spectrally resolved x-ray scattering methods at the LCLS free electron laser. The MEC nanosecond lasers launch counter-propagating shock waves into graphite. At shock coalescence, pressures in excess of 1 Mbar are reached. At given time delay, we measure scattering from the sample using 5070 eV x-ray pulses. We employed curved mosaic and perfect imaging crystals for spatially resolved x-ray scattering. Compared with hydrodynamics simulations, we present data on plasmon dispersion, axial compression gradients and finally carbon melting at shock coalescence. We have indication for a widening of the band gap during compression of the solid, while the band gab fully closes in the melt. UZ was supported by the German Volkswagen Foundation.

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

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.; Dryer, M.

    1978-01-01

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

  10. Shock Formation of Slow Magnetosonic Waves in Coronal Plumes

    NASA Technical Reports Server (NTRS)

    Cuntz, Manfred; Suess, Steven T.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    We investigate the height of shock formation in coroner plumes for slow magnetosonic waves. The models take into account plume geometric spreading, heat conduction and radiative damping. The wave parameters as well as the spreading functions of the plumes and the base magnetic field strengths are given by empirical constraints mostly from Solar and Heliospheric Observatory/Ultraviolet Coronagraph Spectrometer (SOHO/UVCS). Our models show that shock formation occurs at low coronal heights, i.e., within 1.3 solar radius, depending on the model parameters. The shock formation is calculated using the well-established wave breaking condition given by the intersection of C+ characteristics in the space-time plane. Our models show that shock heating by slow magnetosonic waves is expected to be relevant at most heights in solar coronal plumes, although slow magnetosonic waves are most likely not a solely operating energy supply mechanism.

  11. Shock Formation of Slow Magnetosonic Waves in Coronal Plumes

    NASA Technical Reports Server (NTRS)

    Cuntz, Manfred; Suess, Steve; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    We investigate the height of shock formation in coronal plumes for slow magnetosonic waves. The models take into account plume geometric spreading, heat conduction, and radiative damping. The wave parameters as well as the spreading functions of the plumes and the base magnetic field strengths are given by empirical constraints mostly from Solar and Heliospheric Observatory (SOHO)/ Ultraviolet Coronograph Spectrometer (UVCS), Extreme Ultraviolet Imaging Telescope (EIT), Michelson Doppler Imager (MDI), and Large Angle Spectrometric Coronagraph (LASCO). Our models show that shock formation occurs at relatively low coronal heights, typically within 1.2 RsuN, depending on the model parameters. The shock formation is calculated using the well-established wave breaking criterion given by the intersection of C+ characteristics in the space-time plane. Our models show that shock heating by slow magnetosonic waves is expected to be relevant at most heights in solar coronal plumes, although such waves are probably not the main energy supply mechanism.

  12. Shock Waves in a Bose-Einstein Condensate

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Zak, Michail

    2005-01-01

    A paper presents a theoretical study of shock waves in a trapped Bose-Einstein condensate (BEC). The mathematical model of the BEC in this study is a nonlinear Schroedinger equation (NLSE) in which (1) the role of the wave function of a single particle in the traditional Schroedinger equation is played by a space- and time-dependent complex order parameter (x,t) proportional to the square root of the density of atoms and (2) the atoms engage in a repulsive interaction characterized by a potential proportional to | (x,t)|2. Equations that describe macroscopic perturbations of the BEC at zero temperature are derived from the NLSE and simplifying assumptions are made, leading to equations for the propagation of sound waves and the transformation of sound waves into shock waves. Equations for the speeds of shock waves and the relationships between jumps of velocity and density across shock fronts are derived. Similarities and differences between this theory and the classical theory of sound waves and shocks in ordinary gases are noted. The present theory is illustrated by solving the equations for the example of a shock wave propagating in a cigar-shaped BEC.

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  14. Shock waves in water at low energy pulsed electric discharges

    NASA Astrophysics Data System (ADS)

    Pinchuk, M. E.; Kolikov, V. A.; Rutberg, Ph G.; Leks, A. G.; Dolinovskaya, R. V.; Snetov, V. N.; Stogov, A. Yu

    2012-12-01

    Experimental results of shock wave formation and propagation in water at low energy pulsed electric discharges are presented. To study the hydrodynamic structure of the shock waves, the direct shadow optical diagnostic device with time resolution of 5 ns and spatial resolution of 0.1 mm was designed and developed. Synchronization of the diagnostic and electrodischarge units by the fast optocouplers was carried out. The dependences of shock wave velocities after breakdown of interelectrode gap for various energy inputs (at range of <=1 J) into discharge were obtained. Based on the experimental results the recommendations for the adjustment parameters of the power supply and load were suggested.

  15. Constant Density Approximations for the Flow Behind Axisymmetric Shock Waves

    NASA Technical Reports Server (NTRS)

    Munson, Albert G.

    1961-01-01

    The incompressible rotational flow equations are used to obtain solutions for the flow behind axisymmetric shock waves with conic longitudinal sections. The nonlinear part of the term due to rotation is retained in the analysis. Numerical results for standoff distance and stagnation point velocity gradient are presented for the case in which the shock wave is a paraboloid, a sphere, or an oblate or prolate ellipsoid. A similarity parameter is proposed which correlates approximately the flow behind geometrically similar shock waves at different free-stream conditions.

  16. Entropy jump across an inviscid shock wave

    NASA Technical Reports Server (NTRS)

    Salas, Manuel D.; Iollo, Angelo

    1995-01-01

    The shock jump conditions for the Euler equations in their primitive form are derived by using generalized functions. The shock profiles for specific volume, speed, and pressure are shown to be the same, however density has a different shock profile. Careful study of the equations that govern the entropy shows that the inviscid entropy profile has a local maximum within the shock layer. We demonstrate that because of this phenomenon, the entropy, propagation equation cannot be used as a conservation law.

  17. Solitary shock waves and adiabatic phase transition in lipid interfaces and nerves

    NASA Astrophysics Data System (ADS)

    Shrivastava, Shamit; Kang, Kevin Heeyong; Schneider, Matthias F.

    2015-01-01

    This study shows that the stability of solitary waves excited in a lipid monolayer near a phase transition requires positive curvature of the adiabats, a known necessary condition in shock compression science. It is further shown that the condition results in a threshold for excitation, saturation of the wave's amplitude, and the splitting of the wave at the phase boundaries. Splitting in particular confirms that a hydrated lipid interface can undergo condensation on adiabatic heating, thus showing retrograde behavior. Finally, using the theoretical insights and state dependence of conduction velocity in nerves, the curvature of the adiabatic state diagram is shown to be closely tied to the thermodynamic blockage of nerve pulse propagation.

  18. Solitary shock waves and adiabatic phase transition in lipid interfaces and nerves.

    PubMed

    Shrivastava, Shamit; Kang, Kevin Heeyong; Schneider, Matthias F

    2015-01-01

    This study shows that the stability of solitary waves excited in a lipid monolayer near a phase transition requires positive curvature of the adiabats, a known necessary condition in shock compression science. It is further shown that the condition results in a threshold for excitation, saturation of the wave's amplitude, and the splitting of the wave at the phase boundaries. Splitting in particular confirms that a hydrated lipid interface can undergo condensation on adiabatic heating, thus showing retrograde behavior. Finally, using the theoretical insights and state dependence of conduction velocity in nerves, the curvature of the adiabatic state diagram is shown to be closely tied to the thermodynamic blockage of nerve pulse propagation.

  19. Electromagnetic shock wave in nonlinear vacuum: exact solution.

    PubMed

    Kovachev, Lubomir M; Georgieva, Daniela A; Kovachev, Kamen L

    2012-10-01

    An analytical approach to the theory of electromagnetic waves in nonlinear vacuum is developed. The evolution of the pulse is governed by a system of nonlinear wave vector equations. An exact solution with its own angular momentum in the form of a shock wave is obtained.

  20. Shock-wave behavior in explosive monocrystals

    SciTech Connect

    Dick, J.J.

    1994-09-09

    The shock response of explosive monocrystals is strongly anisotropic. Shock initiation sensitivity depends strongly on crystal orientation in PETN. This can be understood in terms of steric hindrance to shear during the shock-induced deformation of the molecular crystal. This initiation mechanism appears to be tribochemical rather than thermal.

  1. Bugbuster—survivability of living bacteria upon shock compression

    NASA Astrophysics Data System (ADS)

    Willis, M. J.; Ahrens, T. J.; Bertani, L. E.; Nash, C. Z.

    2006-07-01

    Shock recovery experiments were conducted on suspensions of 10 6/ml E. coli bacteria contained in a water-based medium that is emplaced within stainless steel containers. The water is shocked and recovered. These experiments simulate the environment of bacteria residing either in surface bodies of water or in subsurface water-filled cracks in rocks. Early Earth life is likely to have existed in such environments. However, the E. coli are not believed to be representative of early life and are merely used here for initial experiments. Some 10 - 2 to 10 - 4 of the bacteria population survived initial (800 ns duration) shock pressures in water of 220 and 260 MPa. TEM images of shock recovered bacteria indicate cell wall rupture and delamination. This appears to be the mortality mechanism. The TEM images indicate cell wall indentations may be occurring as would be consistent with Rayleigh-Taylor or Richtmyer-Meshkov fluid instabilities. In the present case, we consider the experiments as representing three layers of fluids: (1) The water-based medium, a stronger and possibly denser cell wall medium, and the interior of the cell cytoplasm. Variations of only 10-15% are expected in density. (2) A second mechanism that may cause cell wall failure is the multiple shock (nearly isentropic) compression freezing of liquid water medium into ice VI or ice VII high pressure phase that are 20% to 25% denser than the liquid. The decrease in volume associated with the transformation is expected to induce overpressures in the still liquid cell cytoplasm. Cell dynamic tensile wall strength thus appears to be a critical parameter from either of the above failure modes. Because the strain rate dependence of cell wall tensile strength is unstudied, we utilize the Grady and Lipkin [D.E. Grady, L. Lipkin, Criteria for impulsive rock fracture, Geophys. Res. Lett. 7 (1980) 255-258] model of tensile failure versus time scale (strain rate). Our single datum is fit to this law and we assume

  2. X-Ray Diffraction of Shock Compressed H2O

    NASA Astrophysics Data System (ADS)

    Gleason, A. E.

    2014-12-01

    H2O, critical for life and ubiquitous in biology, is one of the most abundant molecules in the solar system and is relevant to many fields, including fundamental physics and chemistry. Phase transformation information of H2O is also important to applied areas like planetary science where it is a constituent of giant planets Neptune and Uranus, icy satellites (e.g., Europa, Ganymede), and extrasolar planets (icy "super-Earths"). Using the MEC (Matter in Extreme Conditions) hutch at LCLS, we reach simultaneous high pressure (P) and temperature (T) with laser-driven shock waves and the capability of taking snapshots during a dynamic process with the X-ray Free Electron Laser (xFEL). We report the only shock-driven diffraction data on H2O ever collected to date, and examine time-resolved diffraction from ice Ih to high pressure ice VII. At 2 Mbar we find evidence of ice X - this has significant implications for planetary interiors and providing a bound for the onset of the superionic phase.

  3. Shock wave amplification by fabric materials

    NASA Astrophysics Data System (ADS)

    Thom, C. G.; Cronin, D. S.

    2009-04-01

    It has been shown that, when exposed to air shock waves, soft materials such as fabrics can lead to amplification of the peak pressure measured on a reflecting surface behind the fabric. This occurs for a wide range of fabric configurations, including those used in soft-ballistic protection. The goal of this study was to validate a numerical model to develop an improved understanding of this phenomenon and investigate different fabric parameters, including density, permeability and standoff, and their influence on blast amplification. The investigation of fabric parameters was carried out using numerical simulations in an explicit finite element code with coupled fluid-structure interaction. The benefit of this method was the ability to isolate individual parameters. The model predicted similar trends to existing experimental data, though the numerically predicted peak pressures were consistently higher than the experimental values. The parametric study showed that low permeability fabrics result in the highest pressure amplifications. At areal densities on the order 100 g/m2, typical of single layer fabrics, amplification also increased with areal density for low permeability materials.

  4. Shock wave perturbation decay in granular materials

    SciTech Connect

    Vogler, Tracy J.

    2015-11-05

    A technique in which the evolution of a perturbation in a shock wave front is monitored as it travels through a sample is applied to granular materials. Although the approach was originally conceived as a way to measure the viscosity of the sample, here it is utilized as a means to probe the deviatoric strength of the material. Initial results for a tungsten carbide powder are presented that demonstrate the approach is viable. Simulations of the experiments using continuum and mesoscale modeling approaches are used to better understand the experiments. The best agreement with the limited experimental data is obtained for the mesoscale model, which has previously been shown to give good agreement with planar impact results. The continuum simulations indicate that the decay of the perturbation is controlled by material strength but is insensitive to the compaction response. Other sensitivities are assessed using the two modeling approaches. The simulations indicate that the configuration used in the preliminary experiments suffers from certain artifacts and should be modified to remove them. As a result, the limitations of the current instrumentation are discussed, and possible approaches to improve it are suggested.

  5. Shock wave perturbation decay in granular materials

    DOE PAGES

    Vogler, Tracy J.

    2015-11-05

    A technique in which the evolution of a perturbation in a shock wave front is monitored as it travels through a sample is applied to granular materials. Although the approach was originally conceived as a way to measure the viscosity of the sample, here it is utilized as a means to probe the deviatoric strength of the material. Initial results for a tungsten carbide powder are presented that demonstrate the approach is viable. Simulations of the experiments using continuum and mesoscale modeling approaches are used to better understand the experiments. The best agreement with the limited experimental data is obtainedmore » for the mesoscale model, which has previously been shown to give good agreement with planar impact results. The continuum simulations indicate that the decay of the perturbation is controlled by material strength but is insensitive to the compaction response. Other sensitivities are assessed using the two modeling approaches. The simulations indicate that the configuration used in the preliminary experiments suffers from certain artifacts and should be modified to remove them. As a result, the limitations of the current instrumentation are discussed, and possible approaches to improve it are suggested.« less

  6. Observation of cavitation during shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Bailey, Michael R.; Crum, Lawrence A.; Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Evan, Andrew P.; Sapozhnikov, Oleg A.; Cleveland, Robin O.

    2005-04-01

    A system was built to detect cavitation in pig kidney during shock wave lithotripsy (SWL) with a Dornier HM3 lithotripter. Active detection, using echo on B-mode ultrasound, and passive cavitation detection (PCD), using coincident signals on confocal, orthogonal receivers, were equally sensitive and were used to interrogate the renal collecting system (urine) and the kidney parenchyma (tissue). Cavitation was detected in urine immediately upon SW administration in urine or urine plus X-ray contrast agent, but in tissue, cavitation required hundreds of SWs to initiate. Localization of cavitation was confirmed by fluoroscopy, sonography, and by thermally marking the kidney using the PCD receivers as high intensity focused ultrasound sources. Cavitation collapse times in tissue and native urine were about the same but less than in urine after injection of X-ray contrast agent. Cavitation, especially in the urine space, was observed to evolve from a sparse field to a dense field with strong acoustic collapse emissions to a very dense field that no longer produced detectable collapse. The finding that cavitation occurs in kidney tissue is a critical step toward determining the mechanisms of tissue injury in SWL. [Work sup ported by NIH (DK43881, DK55674, FIRCA), ONRIFO, CRDF and NSBRI SMS00203.

  7. Shock wave driven microparticles for pharmaceutical applications

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Takayama, K.; Gojani, A.; Hosseini, S. H. R.

    2008-10-01

    Ablation created by a Q-switched Nd:Yttrium Aluminum Garnet (Nd:YAG) laser beam focusing on a thin aluminum foil surface spontaneously generates a shock wave that propagates through the foil and deforms it at a high speed. This high-speed foil deformation can project dry micro- particles deposited on the anterior surface of the foil at high speeds such that the particles have sufficient momentum to penetrate soft targets. We used this method of particle acceleration to develop a drug delivery device to deliver DNA/drug coated microparticles into soft human-body targets for pharmaceutical applications. The device physics has been studied by observing the process of particle acceleration using a high-speed video camera in a shadowgraph system. Though the initial rate of foil deformation is over 5 km/s, the observed particle velocities are in the range of 900-400 m/s over a distance of 1.5-10 mm from the launch pad. The device has been tested by delivering microparticles into liver tissues of experimental rats and artificial soft human-body targets, modeled using gelatin. The penetration depths observed in the experimental targets are quite encouraging to develop a future clinical therapeutic device for treatments such as gene therapy, treatment of cancer and tumor cells, epidermal and mucosal immunizations etc.

  8. Dispersive shock waves and modulation theory

    NASA Astrophysics Data System (ADS)

    El, G. A.; Hoefer, M. A.

    2016-10-01

    There is growing physical and mathematical interest in the hydrodynamics of dissipationless/dispersive media. Since G.B. Whitham's seminal publication fifty years ago that ushered in the mathematical study of dispersive hydrodynamics, there has been a significant body of work in this area. However, there has been no comprehensive survey of the field of dispersive hydrodynamics. Utilizing Whitham's averaging theory as the primary mathematical tool, we review the rich mathematical developments over the past fifty years with an emphasis on physical applications. The fundamental, large scale, coherent excitation in dispersive hydrodynamic systems is an expanding, oscillatory dispersive shock wave or DSW. Both the macroscopic and microscopic properties of DSWs are analyzed in detail within the context of the universal, integrable, and foundational models for uni-directional (Korteweg-de Vries equation) and bi-directional (Nonlinear Schrödinger equation) dispersive hydrodynamics. A DSW fitting procedure that does not rely upon integrable structure yet reveals important macroscopic DSW properties is described. DSW theory is then applied to a number of physical applications: superfluids, nonlinear optics, geophysics, and fluid dynamics. Finally, we survey some of the more recent developments including non-classical DSWs, DSW interactions, DSWs in perturbed and inhomogeneous environments, and two-dimensional, oblique DSWs.

  9. Whistler wave bursts upstream of the Uranian bow shock

    NASA Technical Reports Server (NTRS)

    Smith, Charles W.; Goldstein, Melvyn L.; Wong, Hung K.

    1989-01-01

    Observations of magnetic field wave bursts upstream of the Uranian bow shock are reported which were recorded prior to the inbound shock crossing. Three wave types are identified. One exhibits a broad spectral enhancement from a few millihertz to about 50 mHz and is seen from 17 to 10 hr prior to the inbound shock crossing. It is argued that these waves are whistler waves that have propagated upstream from the shock. A second wave type has a spacecraft frame frequency between 20 and 40 mHz, is seen only within or immediately upstream of the shock pedestal, is right-hand polarized in the spacecraft frame, and has a typical burst duration of 90 s. The third wave type has a spacecraft frame frequency of about 0.15 Hz, is seen exclusively within the shock pedestal, is left-hand polarized in the spacecraft frame, and has a burst duration lasting up to 4 min. It is argued that the low-frequency bursts are whistler waves with phase speed comparable to, but in excess of, the solar wind speed.

  10. Propagation of impact-induced shock waves in porous sandstone using mesoscale modeling

    NASA Astrophysics Data System (ADS)

    GÜLdemeister, Nicole; WÜNnemann, Kai; Durr, Nathanael; Hiermaier, Stefan

    2013-01-01

    Abstract-Generation and propagation of <span class="hlt">shock</span> <span class="hlt">waves</span> by meteorite impact is significantly affected by material properties such as porosity, water content, and strength. The objective of this work was to quantify processes related to the <span class="hlt">shock</span>-induced compaction of pore space by numerical modeling, and compare the results with data obtained in the framework of the Multidisciplinary Experimental and Modeling Impact Research Network (MEMIN) impact experiments. We use mesoscale models resolving the collapse of individual pores to validate macroscopic (homogenized) approaches describing the bulk behavior of porous and water-saturated materials in large-scale models of crater formation, and to quantify localized <span class="hlt">shock</span> amplification as a result of pore space crushing. We carried out a suite of numerical models of planar <span class="hlt">shock</span> <span class="hlt">wave</span> propagation through a well-defined area (the "sample") of porous and/or water-saturated material. The porous sample is either represented by a homogeneous unit where porosity is treated as a state variable (macroscale model) and water content by an equation of state for mixed material (ANEOS) or by a defined number of individually resolved pores (mesoscale model). We varied porosity and water content and measured thermodynamic parameters such as <span class="hlt">shock</span> <span class="hlt">wave</span> velocity and particle velocity on meso- and macroscales in separate simulations. The mesoscale models provide additional data on the heterogeneous distribution of peak <span class="hlt">shock</span> pressures as a consequence of the complex superposition of reflecting rarefaction <span class="hlt">waves</span> and <span class="hlt">shock</span> <span class="hlt">waves</span> originating from the crushing of pores. We quantify the bulk effect of porosity, the reduction in <span class="hlt">shock</span> pressure, in terms of Hugoniot data as a function of porosity, water content, and strength of a quartzite matrix. We find a good agreement between meso-, macroscale models and Hugoniot data from <span class="hlt">shock</span> experiments. We also propose a combination of a porosity compaction model (ɛ-α model) that was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1890466','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1890466"><span id="translatedtitle">Achieving high-density states through <span class="hlt">shock-wave</span> loading of precompressed samples</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jeanloz, Raymond; Celliers, Peter M.; Collins, Gilbert W.; Eggert, Jon H.; Lee, Kanani K. M.; McWilliams, R. Stewart; Brygoo, Stéphanie; Loubeyre, Paul</p> <p>2007-01-01</p> <p>Materials can be experimentally characterized to terapascal pressures by sending a laser-induced <span class="hlt">shock</span> <span class="hlt">wave</span> through a sample that is precompressed inside a diamond-anvil cell. This combination of static and dynamic <span class="hlt">compression</span> methods has been experimentally demonstrated and ultimately provides access to the 10- to 100-TPa (0.1–1 Gbar) pressure range that is relevant to planetary science, testing first-principles theories of condensed matter, and experimentally studying a new regime of chemical bonding. PMID:17494771</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17494771','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17494771"><span id="translatedtitle">Achieving high-density states through <span class="hlt">shock-wave</span> loading of precompressed samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jeanloz, Raymond; Celliers, Peter M; Collins, Gilbert W; Eggert, Jon H; Lee, Kanani K M; McWilliams, R Stewart; Brygoo, Stéphanie; Loubeyre, Paul</p> <p>2007-05-29</p> <p>Materials can be experimentally characterized to terapascal pressures by sending a laser-induced <span class="hlt">shock</span> <span class="hlt">wave</span> through a sample that is precompressed inside a diamond-anvil cell. This combination of static and dynamic <span class="hlt">compression</span> methods has been experimentally demonstrated and ultimately provides access to the 10- to 100-TPa (0.1-1 Gbar) pressure range that is relevant to planetary science, testing first-principles theories of condensed matter, and experimentally studying a new regime of chemical bonding. PMID:17494771</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/948551','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/948551"><span id="translatedtitle">Nonstandard jump functions for radially symmetric <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baty, Roy S.; Tucker, Don H.; Stanescu, Dan</p> <p>2008-10-01</p> <p>Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic <span class="hlt">shock</span> <span class="hlt">waves</span>. It is assumed that the <span class="hlt">shock</span> <span class="hlt">wave</span> jumps occur on infinitesimal intervals, and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a <span class="hlt">shock</span> <span class="hlt">wave</span>. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic <span class="hlt">shock</span> <span class="hlt">waves</span> coincide in a nonstandard sense for a specified density jump function</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/960917','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/960917"><span id="translatedtitle">Nonstandard jump functions for radically symmetric <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baty, Roy S; Tucker, Don H; Stanescu, Dan</p> <p>2008-01-01</p> <p>Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic <span class="hlt">shock</span> <span class="hlt">waves</span>. It is assumed that the <span class="hlt">shock</span> <span class="hlt">wave</span> jumps occur on infinitesimal intervals and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a <span class="hlt">shock</span> <span class="hlt">wave</span>. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic <span class="hlt">shock</span> <span class="hlt">waves</span> coincide in a nonstandard sense for a specified density jump function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21537841','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21537841"><span id="translatedtitle">Density inhomogeneity driven electrostatic <span class="hlt">shock</span> <span class="hlt">waves</span> in planetary rings</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Masood, W.; Siddiq, M.; Rizvi, H.; Haque, Q.; Hasnain, H.</p> <p>2011-05-15</p> <p>Dust inertia and background density driven dust drift <span class="hlt">shock</span> <span class="hlt">waves</span> are theoretically studied in a rotating planetary environment and are subsequently applied to the planetary rings where the collisional effects are pronounced. It has been found that the system under consideration admits significant <span class="hlt">shock</span> formation if the collision frequency is of the order of or less than the rotational frequency of the Saturn's rings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22341891','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22341891"><span id="translatedtitle">Grain destruction in a supernova remnant <span class="hlt">shock</span> <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Raymond, John C.; Gaetz, Terrance J.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Sankrit, Ravi</p> <p>2013-12-01</p> <p>Dust grains are sputtered away in the hot gas behind <span class="hlt">shock</span> fronts in supernova remnants (SNRs), gradually enriching the gas phase with refractory elements. We have measured emission in C IV λ1550 from C atoms sputtered from dust in the gas behind a non-radiative <span class="hlt">shock</span> <span class="hlt">wave</span> in the northern Cygnus Loop. Overall, the intensity observed behind the <span class="hlt">shock</span> agrees approximately with predictions from model calculations that match the Spitzer 24 μm and the X-ray intensity profiles. Thus, these observations confirm the overall picture of dust destruction in SNR <span class="hlt">shocks</span> and the sputtering rates used in models. However, there is a discrepancy in that the C IV intensity 10'' behind the <span class="hlt">shock</span> is too high compared with the intensities at the <span class="hlt">shock</span> and 25'' behind it. Variations in the density, hydrogen neutral fraction, and the dust properties over parsec scales in the pre-<span class="hlt">shock</span> medium limit our ability to test dust destruction models in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140013351','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140013351"><span id="translatedtitle">Grain Destruction in a Supernova Remnant <span class="hlt">Shock</span> <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raymond, John C.; Ghavamian, Parviz; Williams, Brian J.; Blair, William P.; Borkowski, Kazimierz J.; Gaetz, Terrance J.; Sankrit, Ravi</p> <p>2014-01-01</p> <p>Dust grains are sputtered away in the hot gas behind <span class="hlt">shock</span> fronts in supernova remnants, gradually enriching the gas phase with refractory elements. We have measured emission in C IV (lambda)1550 from C atoms sputtered from dust in the gas behind a non-radiative <span class="hlt">shock</span> <span class="hlt">wave</span> in the northern Cygnus Loop. Overall, the intensity observed behind the <span class="hlt">shock</span> agrees approximately with predictions from model calculations that match the Spitzer 24 micron and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR <span class="hlt">shocks</span> and the sputtering rates used in models. However, there is a discrepancy in that the CIV intensity 10'' behind the <span class="hlt">shock</span> is too high compared to the intensities at the <span class="hlt">shock</span> and 25'' behind it. Variations in the density, hydrogen neutral fraction and the dust properties over parsec scales in the pre- <span class="hlt">shock</span> medium limit our ability to test dust destruction models in detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5320531','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5320531"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span> in luminous early-type stars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Castor, J.I.</p> <p>1986-07-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> that occur in stellar atmospheres have their origin in some hydrodynamic instability of the atmosphere itself or of the stellar interior. In luminous early-type stars these two possibilities are represented by <span class="hlt">shocks</span> due to an unstable radiatively-accelerated wind, and to <span class="hlt">shocks</span> generated by the non-radial pulsations known to be present in many or most OB stars. This review is concerned with the structure and development of the <span class="hlt">shocks</span> in these two cases, and especially with the mass loss that may be due specifically to the <span class="hlt">shocks</span>. Pulsation-produced <span class="hlt">shocks</span> are found to be very unfavorable for causing mass loss, owing to the great radiation efficiency that allows them to remain isothermal. The situation regarding radiatively-driven <span class="hlt">shocks</span> remains unclear, awaiting detailed hydrodynamics calculations. 20 refs., 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000STIN...0314316N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000STIN...0314316N"><span id="translatedtitle">Historical Background of Ultrahigh Pressure <span class="hlt">Shock</span> <span class="hlt">Compression</span> Experiments at LLNL: 1973 to 2000</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nellis, W. J.</p> <p>2000-10-01</p> <p>My purpose is to recount the historical development of ultrahigh pressure <span class="hlt">shock</span> <span class="hlt">compression</span> experiments at LLNL, which I experienced in the period 1973 to 2000. I used several experimental techniques: <span class="hlt">shock</span>-impedance-match experiments using planar <span class="hlt">shock</span> <span class="hlt">waves</span> driven by nuclear explosives (NIMs), the Janus Laser, a railgun, and a two-stage light-gas gun. Two things have motivated me: (1) the interaction between programmatic needs and scientific understanding (i.e., there are lots of scientifically interesting things to do here which are important programmatically) and (2) accurate experimental data are required to develop accurate theoretical models (or as Feynman said, 'If it (theory) disagrees with experiment, it is wrong'). The iteration between experiment and theory is commonly known as the scientific method. I arrived at LLNL with a PhD in Condensed Matter Physics (thesis on measuring thermal and electrical conductivities of rare-earth single crystals), postdoctoral experience (measuring electrical and magnetic properties of Pu, Np, and U intermetallic compounds and alloys), three years experience teaching 7-8 different undergraduate physics courses while running the college's computer terminal, a belief in the scientific method, and an intense interest in understanding materials physics. I managed to get one of the few jobs available in physics in 1973.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6263278','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6263278"><span id="translatedtitle">Vibrational spectroscopy of <span class="hlt">shock-compressed</span> fluid N/sub 2/ and O/sub 2/</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schmidt, S.C.; Moore, D.S.; Shaw, M.S.; Johnson, J.D.</p> <p>1987-01-01</p> <p>Single-pulse, multiplex, coherent anti-Stokes Raman scattering (CARS) was used to observe the vibrational spectra of liquid N/sub 2/ <span class="hlt">shock-compressed</span> to several pressures and temperatures up to 41 GPa and 5200 K and liquid O/sub 2/ <span class="hlt">shock-compressed</span> to several pressures and temperatures up to 10 GPa and 1000 K. For N/sub 2/, the experimental spectra were compared to synthetic spectra calculated using a semiclassical model for CARS intensities and estimated vibrational frequencies, peak Raman susceptibilities and Raman line widths. The question of excited state populations in the <span class="hlt">shock-compressed</span> state is addressed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6195917','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6195917"><span id="translatedtitle">Vibrational spectroscopy of <span class="hlt">shock-compressed</span> fluid N/sub 2/ and O/sub 2/</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schmidt, S.C.; Moore, D.S.; Shaw, M.S.; Johnson, J.D.</p> <p>1987-01-01</p> <p>Single-pulse multiplex coherent anti-Stokes Raman scattering (CARS) was used to observe the vibrational spectra of liquid N/sub 2/ <span class="hlt">shock-compressed</span> to several pressures and temperatures up to 41 GPa and 5200 K and liquid O/sub 2/ <span class="hlt">shock-compressed</span> to several pressures and temperatures up to 10 GPa and 1000 K. For N/sub 2/, the experimental spectra were compared to synthetic spectra calculated using a semiclassical model for CARS intensities and estimated vibrational frequencies, peak Raman susceptibilities, and Raman line widths. The question of excited state populations in the <span class="hlt">shock-compressed</span> state is addressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhyD..310...19W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhyD..310...19W"><span id="translatedtitle">A geometric singular perturbation approach for planar stationary <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zhuopu; Zhang, Jiazhong; Ren, Junheng; Aslam, Muhammad Nauman</p> <p>2015-08-01</p> <p>The non-linear non-equilibrium nature of <span class="hlt">shock</span> <span class="hlt">waves</span> in gas dynamics is investigated for the planar case. Along each streamline, the Euler equations with non-equilibrium pressure are reduced to a set of ordinary differential equations defining a slow-fast system, and geometric singular perturbation theory is applied. The proposed theory shows that an orbit on the slow manifold corresponds to the smooth part of the solution to the Euler equation, where non-equilibrium effects are negligible; and a relaxation motion from the unsteady to the steady branch of the slow manifold corresponds to a <span class="hlt">shock</span> <span class="hlt">wave</span>, where the flow relaxes from non-equilibrium to equilibrium. Recognizing the <span class="hlt">shock</span> <span class="hlt">wave</span> as a fast motion is found to be especially useful for <span class="hlt">shock</span> <span class="hlt">wave</span> detection when post-processing experimental measured or numerical calculated flow fields. Various existing <span class="hlt">shock</span> detection methods can be derived from the proposed theory in a rigorous mathematical manner. The proposed theory provides a new <span class="hlt">shock</span> detection method based on its non-linear non-equilibrium nature, and may also serve as the theoretical foundation for many popular <span class="hlt">shock</span> <span class="hlt">wave</span> detection techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ShWav..17..225K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ShWav..17..225K"><span id="translatedtitle">Plasma mitigation of <span class="hlt">shock</span> <span class="hlt">wave</span>: experiments and theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuo, Spencer P.</p> <p>2007-12-01</p> <p>Two types of plasma spikes, generated by on-board 60 Hz periodic and pulsed dc electric discharges in front of two slightly different wind tunnel models, were used to demonstrate the non-thermal plasma techniques for <span class="hlt">shock</span> <span class="hlt">wave</span> mitigation. The experiments were conducted in a Mach 2.5 wind tunnel. (1) In the periodic discharge case, the results show a transformation of the <span class="hlt">shock</span> from a well-defined attached <span class="hlt">shock</span> into a highly curved <span class="hlt">shock</span> structure, which has increased <span class="hlt">shock</span> angle and also appears in diffused form. As shown in a sequence with increasing discharge intensity, the <span class="hlt">shock</span> in front of the model moves upstream to become detached with increasing standoff distance from the model and is eliminated near the peak of the discharge. The power measurements exclude the heating effect as a possible cause of the observed <span class="hlt">shock</span> <span class="hlt">wave</span> modification. A theory using a cone model as the <span class="hlt">shock</span> <span class="hlt">wave</span> generator is presented to explain the observed plasma effect on <span class="hlt">shock</span> <span class="hlt">wave</span>. The analysis shows that the plasma generated in front of the model can effectively deflect the incoming flow; such a flow deflection modifies the structure of the <span class="hlt">shock</span> <span class="hlt">wave</span> generated by the cone model, as shown by the numerical results, from a conic shape to a curved one. The <span class="hlt">shock</span> front moves upstream with a larger <span class="hlt">shock</span> angle, matching well with that observed in the experiment. (2) In the pulsed dc discharge case, hollow cone-shaped plasma that envelops the physical spike of a truncated cone model is produced in the discharge; consequently, the original bow <span class="hlt">shock</span> is modified to a conical <span class="hlt">shock</span>, equivalent to reinstating the model into a perfect cone and to increase the body aspect ratio by 70%. A significant <span class="hlt">wave</span> drag reduction in each discharge is inferred from the pressure measurements; at the discharge maximum, the pressure on the frontal surface of the body decreases by more than 30%, the pressure on the cone surface increases by about 5%, whereas the pressure on the cylinder surface remains</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8478458','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8478458"><span id="translatedtitle">Ultrasonography and biliary extracorporeal <span class="hlt">shock-wave</span> lithotripsy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jakobeit, C; Greiner, L</p> <p>1993-05-01</p> <p>The results of <span class="hlt">shock-wave</span> treatment of gallbladder stones depend to a very high degree on the quality and expertise of ultrasonography applied before, during, and after <span class="hlt">shock-wave</span> disintegration of the stones. Ultrasonography is decisive in evaluating the inclusion criteria; it is the method of choice for directing the shockwave energy at the stones and monitoring the disintegration process. It is the only diagnostic modality to really demonstrate the gallbladder being free from stones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.........6K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.........6K"><span id="translatedtitle">Tracking kidney stones with sound during <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kracht, Jonathan M.</p> <p></p> <p>The prevalence of kidney stones has increased significantly over the past decades. One of the primary treatments for kidney stones is <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy which focuses acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> onto the stone in order to fragment it into pieces that are small enough to pass naturally. This typically requires a few thousand <span class="hlt">shock</span> <span class="hlt">waves</span> delivered at a rate of about 2 Hz. Although lithotripsy is the only non-invasive treatment option for kidney stories, both acute and chronic complications have been identified which could be reduced if fewer <span class="hlt">shock</span> <span class="hlt">waves</span> were used. One factor that could be used to reduce the number of <span class="hlt">shock</span> <span class="hlt">waves</span> is accounting for the motion of the stone which causes a portion of the delivered <span class="hlt">shock</span> <span class="hlt">waves</span> to miss the stone, yielding no therapeutic benefit. Therefore identifying when the stone is not in focus would allow tissue to be spared without affecting fragmentation. The goal of this thesis is to investigate acoustic methods to track the stone in real-time during lithotripsy in order to minimize poorly-targeted <span class="hlt">shock</span> <span class="hlt">waves</span>. A relatively small number of low frequency ultrasound transducers were used in pulse-echo mode and a novel optimization routine based on time-of-flight triangulation is used to determine stone location. It was shown that the accuracy of the localization may be estimated without knowing the true stone location. This method performed well in preliminary experiments but the inclusion of tissue-like aberrating layers reduced the accuracy of the localization. Therefore a hybrid imaging technique employing DORT (Decomposition of the Time Reversal Operator) and the MUSIC (Multiple Signal Classification) algorithm was developed. This method was able to localize kidney stories to within a few millimeters even in the presence of an aberrating layer. This would be sufficient accuracy for targeting lithotripter <span class="hlt">shock</span> <span class="hlt">waves</span>. The conclusion of this work is that tracking kidney stones with low frequency ultrasound should be effective clinically.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/9443395','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9443395"><span id="translatedtitle">In vivo transfection of melanoma cells by lithotripter <span class="hlt">shock</span> <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bao, S; Thrall, B D; Gies, R A; Miller, D L</p> <p>1998-01-15</p> <p>The potential for gene transfection during <span class="hlt">shock</span> <span class="hlt">wave</span> tumor therapy was evaluated by searching for <span class="hlt">shock</span> <span class="hlt">wave</span>-induced DNA transfer in mouse tumor cells. B16 mouse melanoma cells were cultured by standard methods and implanted s.c. in female C57BL/6 mice 10-14 days before treatment. A luciferase reporter vector was used as the DNA plasmid for intratumoral injection at 0.2 mg/ml tumor. Air at 10% of tumor volume was injected after the DNA in some tumors to enhance acoustic cavitation activity. The <span class="hlt">shock</span> <span class="hlt">wave</span> generation system was similar to a Dornier HM-3 lithotripter with pressure amplitudes of 24.4 MPa peak positive and 5.2 MPa peak negative. Luciferase production in isolated tumor cells was measured with a luminometer 1 day after treatment to assess gene transfer and expression. Exposure to 800 <span class="hlt">shock</span> <span class="hlt">waves</span>, followed by immediate isolation and culture of tumor cells for 1 day, yielded 1.1 (0.43 SE) pg/10(6) cells for plasmid injection only and 7.5 (2.5 SE) pg/10(6) cells for plasmid plus air injection. Significantly increased luciferase production, relative to shams, occurred for 200-, 400-, 800-, and 1200-<span class="hlt">shock</span> <span class="hlt">wave</span> treatments with plasmid and air injection. Exposure with the isolation of tumor cells delayed for a day to allow gene expression within the growing tumors gave increased luciferase production for 100- and 400-<span class="hlt">shock</span> <span class="hlt">wave</span> exposures without and with air injection. Gene transfer therefore can be induced during lithotripter <span class="hlt">shock</span> <span class="hlt">wave</span> treatment in vivo, particularly with enhanced acoustic cavitation, which supports the concept that gene and <span class="hlt">shock</span> <span class="hlt">wave</span> therapy might be advantageously merged. PMID:9443395</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/450214','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/450214"><span id="translatedtitle">Interaction of turbulent plasma flow with a hypersonic <span class="hlt">shock</span> <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Belay, K.; Valentine, J.M.; Williams, R.L.; Johnson, J.A. III</p> <p>1997-02-01</p> <p>A transient increase is observed in both the spectral energy decay rate and the degree of chaotic complexity at the interface of a <span class="hlt">shock</span> <span class="hlt">wave</span> and a turbulent ionized gas. Even though the gas is apparently brought to rest by the <span class="hlt">shock</span> <span class="hlt">wave</span>, no evidence is found either of prompt relaminarization or of any systematic influence of end-wall material thermal conductivities on the turbulence parameters. {copyright} {ital 1997 American Institute of Physics.}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22047096','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22047096"><span id="translatedtitle">Dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in two temperatures charged dusty grains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>El-Shewy, E. K.; Abdelwahed, H. G.; Elmessary, M. A.</p> <p>2011-11-15</p> <p>The reductive perturbation method has been used to derive the Korteweg-de Vries-Burger equation and modified Korteweg-de Vries-Burger for dust acoustic <span class="hlt">shock</span> <span class="hlt">waves</span> in a homogeneous unmagnetized plasma having electrons, singly charged ions, hot and cold dust species with Boltzmann distributions for electrons and ions in the presence of the cold (hot) dust viscosity coefficients. The behavior of the <span class="hlt">shock</span> <span class="hlt">waves</span> in the dusty plasma has been investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/12401391','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/12401391"><span id="translatedtitle">In vitro sonoluminescence and sonochemistry studies with an electrohydraulic <span class="hlt">shock-wave</span> lithotripter.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matula, Thomas J; Hilmo, Paul R; Bailey, Michael R; Crum, Lawrence A</p> <p>2002-09-01</p> <p>Sonoluminescence and sonochemistry from a cavitation field generated by an electrohydraulic <span class="hlt">shock-wave</span> lithotripter were investigated as functions of spark discharge voltage (13 to 21 kV) and pulse-repetition frequency (PRF) (0.5 to 2.0 Hz). Sonochemical activity, measured with an iodide dosimeter, increased with both voltage and PRF. Sonoluminescence was measured in an acoustically matched light-tight box. The envelope of the light intensity was measured in a temporally gated region extending from the initial arrival of the <span class="hlt">shock</span> <span class="hlt">wave</span> (resulting in bubble <span class="hlt">compression</span>) to the final inertial collapse of the bubble cloud, which follows hundreds of micros after passage of the <span class="hlt">shock</span> <span class="hlt">wave</span>. The initial <span class="hlt">compression</span> resulted in greater sonoluminescence emissions, suggesting that the initial bubble <span class="hlt">compression</span> due to the leading positive pressure spike from the lithotripter generated higher temperatures than the inertial collapse of the bubble. These unexpected results are consistent with some recent calculations in which the vapor pressure of the liquid limits compressional heating. PMID:12401391</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910017826','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910017826"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> interaction with an abrupt area change</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Salas, Manuel D.</p> <p>1991-01-01</p> <p>The <span class="hlt">wave</span> patterns that occur when a <span class="hlt">shock</span> <span class="hlt">wave</span> interacts with an abrupt area changed are analyzed in terms of the incident <span class="hlt">shock</span> <span class="hlt">wave</span> Mach number and area-jump ratio. The solutions predicted by a semi-similar models are in good agreement with those obtained numerically from the quasi-one-dimensional time-dependent Euler equations. The entropy production for the <span class="hlt">wave</span> system is defined and the principle of minimum entropy production is used to resolve a nonuniqueness problem of the self-similar model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000021168','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000021168"><span id="translatedtitle">Particle Acceleration by Cme-driven <span class="hlt">Shock</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reames, Donald V.</p> <p>1999-01-01</p> <p>In the largest solar energetic particle (SEP) events, acceleration occurs at <span class="hlt">shock</span> <span class="hlt">waves</span> driven out from the Sun by coronal mass ejections (CMEs). Peak particle intensities are a strong function of CME speed, although the intensities, spectra, and angular distributions of particles escaping the <span class="hlt">shock</span> are highly modified by scattering on Alfven <span class="hlt">waves</span> produced by the streaming particles themselves. Element abundances vary in complex ways because ions with different values of Q/A resonate with different parts of the <span class="hlt">wave</span> spectrum, which varies with space and time. Just recently, we have begun to model these systematic variations theoretically and to explore other consequences of proton-generated <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24606251','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24606251"><span id="translatedtitle">Shear <span class="hlt">waves</span> in inhomogeneous, <span class="hlt">compressible</span> fluids in a gravity field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Godin, Oleg A</p> <p>2014-03-01</p> <p>While elastic solids support compressional and shear <span class="hlt">waves</span>, <span class="hlt">waves</span> in ideal <span class="hlt">compressible</span> fluids are usually thought of as compressional <span class="hlt">waves</span>. Here, a class of acoustic-gravity <span class="hlt">waves</span> is studied in which the dilatation is identically zero, and the pressure and density remain constant in each fluid particle. These shear <span class="hlt">waves</span> are described by an exact analytic solution of linearized hydrodynamics equations in inhomogeneous, quiescent, inviscid, <span class="hlt">compressible</span> fluids with piecewise continuous parameters in a uniform gravity field. It is demonstrated that the shear acoustic-gravity <span class="hlt">waves</span> also can be supported by moving fluids as well as quiescent, viscous fluids with and without thermal conductivity. Excitation of a shear-<span class="hlt">wave</span> normal mode by a point source and the normal mode distortion in realistic environmental models are considered. The shear acoustic-gravity <span class="hlt">waves</span> are likely to play a significant role in coupling <span class="hlt">wave</span> processes in the ocean and atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24606251','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24606251"><span id="translatedtitle">Shear <span class="hlt">waves</span> in inhomogeneous, <span class="hlt">compressible</span> fluids in a gravity field.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Godin, Oleg A</p> <p>2014-03-01</p> <p>While elastic solids support compressional and shear <span class="hlt">waves</span>, <span class="hlt">waves</span> in ideal <span class="hlt">compressible</span> fluids are usually thought of as compressional <span class="hlt">waves</span>. Here, a class of acoustic-gravity <span class="hlt">waves</span> is studied in which the dilatation is identically zero, and the pressure and density remain constant in each fluid particle. These shear <span class="hlt">waves</span> are described by an exact analytic solution of linearized hydrodynamics equations in inhomogeneous, quiescent, inviscid, <span class="hlt">compressible</span> fluids with piecewise continuous parameters in a uniform gravity field. It is demonstrated that the shear acoustic-gravity <span class="hlt">waves</span> also can be supported by moving fluids as well as quiescent, viscous fluids with and without thermal conductivity. Excitation of a shear-<span class="hlt">wave</span> normal mode by a point source and the normal mode distortion in realistic environmental models are considered. The shear acoustic-gravity <span class="hlt">waves</span> are likely to play a significant role in coupling <span class="hlt">wave</span> processes in the ocean and atmosphere. PMID:24606251</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1426..755C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1426..755C"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">compression</span> and unloading response of 1050 aluminum to 70 GPA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choudhuri, Deep; Gupta, Yogendra M.</p> <p>2012-03-01</p> <p>Using laser-interferometry, <span class="hlt">shock</span> <span class="hlt">compression</span> and unloading profiles were measured in 1050 aluminum <span class="hlt">shocked</span> to ~70 GPa. These results were compared to published data on relatively pure (99.99wt% ultra pure, 1050, 1060, and 1100) and precipitate - hardened (2024, 6061) aluminum. Within experimental scatter, Hugoniots and longitudinal sound speeds (in the <span class="hlt">shocked</span> state) of pure and precipitate-hardened aluminum are quite comparable to 70GPa. This agreement demonstrates that impurity content has minimal influence on the longitudinal stress-volume response and acoustic speeds under <span class="hlt">shock</span> <span class="hlt">compression</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998AIPC..429..483F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998AIPC..429..483F"><span id="translatedtitle">Dynamic strength and inelastic deformation of ceramics under <span class="hlt">shock</span> <span class="hlt">wave</span> loading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, R.; Gupta, Y. M.; Yuan, G.</p> <p>1998-07-01</p> <p>To gain insight into material strength and inelastic deformation of ceramics under plane <span class="hlt">shock</span> <span class="hlt">wave</span> loading, an in-depth study was carried out on polycrystalline silicon carbide (SiC). Two independent methods were used to determine experimentally the material strength in the <span class="hlt">shocked</span> state: 1) lateral piezoresistance gauge measurements, and 2) <span class="hlt">compression</span> and shear <span class="hlt">wave</span> experiments. The two sets of data were in good agreement. The results show that the Poisson's ratio of the SiC increases from 0.162 to 0.194 at the HEL (11.5 GPa). The elastic-inelastic transition is not distinctive. In the <span class="hlt">shocked</span> state, the material supports a maximum shear stress increasing from 4.5 GPa at the HEL to 7.0 GPa at twice the HEL. This post-HEL strength evolution resembles neither catastrophic failure due to massive cracking nor classical plasticity response. Confining stress, inherent in plane <span class="hlt">shock</span> <span class="hlt">wave</span> <span class="hlt">compression</span>, plays a dominant role in such a behavior. The observed inelastic deformation is interpreted qualitatively using an inhomogeneous mechanism involving both in-grain micro-plasticity and highly confined micro-fissures. Quantitatively, the data are summarized into an empirical pressure-dependent strength model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1208837-imaging-shock-waves-diamond-both-high-temporal-spatial-resolution-xfel','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1208837-imaging-shock-waves-diamond-both-high-temporal-spatial-resolution-xfel"><span id="translatedtitle">Imaging <span class="hlt">shock</span> <span class="hlt">waves</span> in diamond with both high temporal and spatial resolution at an XFEL</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Ping, Yuan; Hicks, Damien G.; Beckwith, Martha A.; Collins, Gilbert W.; Higginbotham, Andrew; et al</p> <p>2015-06-18</p> <p>The advent of hard x-ray free-electron lasers (XFELs) has opened up a variety of scientific opportunities in areas as diverse as atomic physics, plasma physics, nonlinear optics in the x-ray range, and protein crystallography. In this article, we access a new field of science by measuring quantitatively the local bulk properties and dynamics of matter under extreme conditions, in this case by using the short XFEL pulse to image an elastic <span class="hlt">compression</span> <span class="hlt">wave</span> in diamond. The elastic <span class="hlt">wave</span> was initiated by an intense optical laser pulse and was imaged at different delay times after the optical pump pulse using magnifiedmore » x-ray phase-contrast imaging. The temporal evolution of the <span class="hlt">shock</span> <span class="hlt">wave</span> can be monitored, yielding detailed information on <span class="hlt">shock</span> dynamics, such as the <span class="hlt">shock</span> velocity, the <span class="hlt">shock</span> front width, and the local <span class="hlt">compression</span> of the material. The method provides a quantitative perspective on the state of matter in extreme conditions.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...810...97S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...810...97S"><span id="translatedtitle">Particle Acceleration at Low Coronal <span class="hlt">Compression</span> Regions and <span class="hlt">Shocks</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schwadron, N. A.; Lee, M. A.; Gorby, M.; Lugaz, N.; Spence, H. E.; Desai, M.; Török, T.; Downs, C.; Linker, J.; Lionello, R.; Mikić, Z.; Riley, P.; Giacalone, J.; Jokipii, J. R.; Kota, J.; Kozarev, K.</p> <p>2015-09-01</p> <p>We present a study on particle acceleration in the low corona associated with the expansion and acceleration of coronal mass ejections (CMEs). Because CME expansion regions low in the corona are effective accelerators over a finite spatial region, we show that there is a rigidity regime where particles effectively diffuse away and escape from the acceleration sites using analytic solutions to the Parker transport equation. This leads to the formation of broken power-law distributions. Based on our analytic solutions, we find a natural ordering of the break energy and second power-law slope (above the break energy) as a function of the scattering characteristics. These relations provide testable predictions for the particle acceleration from low in the corona. Our initial analysis of solar energetic particle observations suggests a range of <span class="hlt">shock</span> <span class="hlt">compression</span> ratios and rigidity dependencies that give rise to the solar energetic particle (SEP) events studied. The wide range of characteristics inferred suggests competing mechanisms at work in SEP acceleration. Thus, CME expansion and acceleration in the low corona may naturally give rise to rapid particle acceleration and broken power-law distributions in large SEP events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22525461','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22525461"><span id="translatedtitle">PARTICLE ACCELERATION AT LOW CORONAL <span class="hlt">COMPRESSION</span> REGIONS AND <span class="hlt">SHOCKS</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schwadron, N. A.; Lee, M. A.; Gorby, M; Lugaz, N.; Spence, H. E.; Desai, M.; Török, T.; Downs, C.; Linker, J.; Lionello, R.; Mikić, Z.; Riley, P.; Giacalone, J.; Jokipii, J. R.; Kota, J.; Kozarev, K.</p> <p>2015-09-10</p> <p>We present a study on particle acceleration in the low corona associated with the expansion and acceleration of coronal mass ejections (CMEs). Because CME expansion regions low in the corona are effective accelerators over a finite spatial region, we show that there is a rigidity regime where particles effectively diffuse away and escape from the acceleration sites using analytic solutions to the Parker transport equation. This leads to the formation of broken power-law distributions. Based on our analytic solutions, we find a natural ordering of the break energy and second power-law slope (above the break energy) as a function of the scattering characteristics. These relations provide testable predictions for the particle acceleration from low in the corona. Our initial analysis of solar energetic particle observations suggests a range of <span class="hlt">shock</span> <span class="hlt">compression</span> ratios and rigidity dependencies that give rise to the solar energetic particle (SEP) events studied. The wide range of characteristics inferred suggests competing mechanisms at work in SEP acceleration. Thus, CME expansion and acceleration in the low corona may naturally give rise to rapid particle acceleration and broken power-law distributions in large SEP events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DPPCO4003B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DPPCO4003B&link_type=ABSTRACT"><span id="translatedtitle">Probing Hotspot Conditions in Spherically <span class="hlt">Shock</span> <span class="hlt">Compressed</span> Matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bachmann, Benjamin; Nilsen, J.; Kritcher, A. L.; Swift, D.; Rygg, J. R.; Collins, G. W.; Divol, L.; Falcone, R. W.; Gaffney, J.; Glenzer, S. H.; Hatarik, R.; Hawreliak, J.; Khan, S.; Kraus, D.; Landen, O. L.; Masters, N.; Nagel, S. R.; Pardini, T.; Zimmerman, G.; Doeppner, T.</p> <p>2015-11-01</p> <p>We present results of an approach to experimentally determine the conditions in the center of a CD2 sphere that has been <span class="hlt">compressed</span> to petapascal pressures by spherically converging <span class="hlt">shocks</span>. By measuring the hotspot size using penumbral imaging, hotspot temperature using two-color spectroscopy, the neutron yield from DD nuclear reactions and the x-ray burn width, we infer average hotspot densities of 43 g/cm3 at 1.6 keV temperature. These conditions correspond to pressures of 4.4 petapascal (44 Gbar) in an ideal gas and 3.5 petapascal from independently performed rad.-hydro. simulations. The experimentally determined neutron yield, temperature and density constrain the EOS in a regime that exceeds previously reported pressures obtained in carbon EOS measurements by three orders of magnitude. The results show a path for constraining the EOS of matter at conditions that have been inaccessible with state-of-the-art experimental EOS techniques. This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344 and LDRD Grant 13-ERD-073</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2923385','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2923385"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> lithotripsy: advances in technology and technique</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lingeman, James E.; McAteer, James A.; Gnessin, Ehud; Evan, Andrew P.</p> <p>2010-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">wave</span> lithotripsy (SWL) is the only noninvasive method for stone removal. Once considered as a primary option for the treatment of virtually all stones, SWL is now recognized to have important limitations that restrict its use. In particular, the effectiveness of SWL is severely limited by stone burden, and treatment with <span class="hlt">shock</span> <span class="hlt">waves</span> carries the risk of acute injury with the potential for long-term adverse effects. Research aiming to characterize the renal response to <span class="hlt">shock</span> <span class="hlt">waves</span> and to determine the mechanisms of <span class="hlt">shock</span> <span class="hlt">wave</span> action in stone breakage and renal injury has begun to suggest new treatment strategies to improve success rates and safety. Urologists can achieve better outcomes by treating at slower <span class="hlt">shock</span> <span class="hlt">wave</span> rate using a step-wise protocol. The aim is to achieve stone comminution using as few <span class="hlt">shock</span> <span class="hlt">waves</span> and at as low a power level as possible. Important challenges remain, including the need to improve acoustic coupling, enhance stone targeting, better determine when stone breakage is complete, and minimize the occurrence of residual stone fragments. New technologies have begun to address many of these issues, and hold considerable promise for the future. PMID:19956196</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020080810','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020080810"><span id="translatedtitle">Energetic Particle Abundances as Probes of an Interplanetary <span class="hlt">Shock</span> <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reames, D. V.; Tylka, A. J.; White, Nicholas E. (Technical Monitor)</p> <p>2002-01-01</p> <p>We examine the unique abundance variations of Fe/O and He/H in solar energetic particles from a W09 event of 2001 April 10, that have leaked through the flank of an interplanetary <span class="hlt">shock</span> launched from W04 on April 9. <span class="hlt">Shock</span> <span class="hlt">waves</span> from both events reach the Wind spacecraft on April 11. During the second event, both Fe/O and He/H begin at low values and rise to maxima near the time of passage of the <span class="hlt">shock</span> <span class="hlt">waves</span>, indicating greater scattering for the species with the highest rigidity at a given velocity. Strong modulation of Fe/O suggests preferential scattering and trapping of Fe by the <span class="hlt">wave</span> spectrum near and behind the intermediate <span class="hlt">shock</span>. A significant factor may be the residual proton-generated <span class="hlt">waves</span> from the very hard proton spectrum accelerated by the early <span class="hlt">shock</span> <span class="hlt">wave</span> prior to the onset of the second event. Thus, ion abundances from the later event probe the residual <span class="hlt">wave</span> spectrum at the earlier <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.2101K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.2101K"><span id="translatedtitle">Extended fusion yield integral using pathway idea in case of <span class="hlt">Shock-compressed</span> heated plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, Dilip; Haubold, Hans</p> <p></p> <p>The extended non-resonant thermonuclear reaction rate probability integral obtained in Haubold and Kumar [Haubold, H.J. and Kumar, D.: 2008, Extension of thermonuclear functions through the pathway model including Maxwell-Boltzmann and Tsallis distributions, Astroparticle Physics, 29, 70-76] is used to evaluate the fusion energy by itegrating it over temperature. The closed form representation of the extended reaction rate integral via Meijer's G-function is expressed as a solution of a homogeneous differential equation. A physical model of Guderley[Guderley G. :1942, Starke kugelige und zylindrische Verdichtungsstsse in der Nhe des Kugelmittelpunktes bzw. der Zylinderachse, Luftfahrtforschung, 19, 302] has been considered for the laser driven hydrodynamical process in a <span class="hlt">compressed</span> fusion plasma and heated strong spherical <span class="hlt">shock</span> <span class="hlt">wave</span>. The fusion yield integral obtained in the paper is compared with the standard fusion yield ob-tained by Haubold and John [Haubold, H.J. and John, R.W.:1981, Analytical representation of the thermonuclear reaction rate and fusion energy production in a spherical plasma <span class="hlt">shock</span> <span class="hlt">wave</span>, Plasma Physics, 5, 399-411]. The pathway parameter used in this paper is given an interpretation in terms of moments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhSS...58.1191K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhSS...58.1191K&link_type=ABSTRACT"><span id="translatedtitle">Change of the kinetics of <span class="hlt">shock-wave</span> deformation and fracture of VT1-0 titanium as a result of annealing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kanel, G. I.; Razorenov, S. V.; Garkushin, G. V.; Pavlenko, A. V.; Malyugina, S. N.</p> <p>2016-06-01</p> <p>The paper presents the results of measurements of <span class="hlt">shock-wave</span> <span class="hlt">compression</span> profiles of VT1-0 titanium samples after rolling and in the annealed state. In the experiments, the pressure of <span class="hlt">shock</span> <span class="hlt">compression</span> and distance passed by the <span class="hlt">wave</span> before emerging to the sample surface were varied. From measurements of the elastic precursor decay and <span class="hlt">compression</span> rate in a plastic <span class="hlt">shock</span> <span class="hlt">wave</span> of different amplitudes, the plastic strain and the corresponding shear stresses in the initial and subsequent stages of high-rate deformation in an elastoplastic <span class="hlt">shock</span> <span class="hlt">wave</span> are determined. It is found that the reduction in the dislocation density as a result of annealing reduces the hardness of the material but significantly increases its dynamic yield strengh, corresponding to the strain rate above 104 s-1. With a reduction in the strain rate, this anomalous difference in the flow stresses is leveled off.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012IAUS..279..335I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012IAUS..279..335I"><span id="translatedtitle">Turbulent Magnetic Field Amplification behind Strong <span class="hlt">Shock</span> <span class="hlt">Waves</span> in GRB and SNR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inoue, Tsuyoshi</p> <p>2012-09-01</p> <p>Using three-dimensional (special relativistic) magnetohydrodynamics simulations, the amplification of magnetic field behind strong <span class="hlt">shock</span> <span class="hlt">wave</span> is studied. In supernova remnants and gamma-ray bursts, strong <span class="hlt">shock</span> <span class="hlt">waves</span> propagate through an inhomogeneous density field. When the <span class="hlt">shock</span> <span class="hlt">wave</span> hit a density bump or density dent, the Richtmyer-Meshkov instability is induced that cause a deformation of the <span class="hlt">shock</span> front. The deformed <span class="hlt">shock</span> leaves vorticity behind the <span class="hlt">shock</span> <span class="hlt">wave</span> that amplifies the magnetic field due to the stretching of field lines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910060876&hterms=hertz&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dhertz','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910060876&hterms=hertz&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dhertz"><span id="translatedtitle">ULF <span class="hlt">waves</span> upstream of the Venus bow <span class="hlt">shock</span> - Properties of one-hertz <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Orlowski, D. S.; Russell, C. T.</p> <p>1991-01-01</p> <p>Pioneer Venus Orbiter data are used here to study the properties of a class of ULF upstream <span class="hlt">waves</span> with relatively high observed frequencies. These <span class="hlt">waves</span> show significant similarity to 'one-Hz' <span class="hlt">waves</span> identified at earth in the ISEE 1 and 2 observations and the whistler <span class="hlt">waves</span> identified earlier by IMP 6 observations. The <span class="hlt">waves</span> appear almost immediately after the spacecraft crosses the magnetic field tangent line to the bow <span class="hlt">shock</span> surface into the region of connected field lines. The <span class="hlt">wave</span> amplitude decreases with distance from the <span class="hlt">shock</span> measured along the magnetic field line. Group velocities calculated using the cold plasma dispersion relation indicate that the <span class="hlt">waves</span> have sufficient upstream velocities to propagate form the <span class="hlt">shock</span> into the solar wind. The totality of observations seem best explained by a source of right-handed whistler mode <span class="hlt">waves</span> at the bow <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDD20003C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDD20003C"><span id="translatedtitle"><span class="hlt">Shock</span>-resolving direct numerical simulations of strong turbulence interacting with a normal <span class="hlt">shock</span> <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Chang-Hsin; Donzis, Diego</p> <p>2015-11-01</p> <p>In many natural and engineering systems, turbulence is found to interact with <span class="hlt">shock</span> <span class="hlt">waves</span>. Thus, canonical interactions between isotropic turbulence and a normal <span class="hlt">shock</span> have been studied extensively, theoretically and numerically, though theories assume the <span class="hlt">shock</span> to be a discontinuity and most simulations have used <span class="hlt">shock</span>-capturing schemes which may miss details of the structure of the <span class="hlt">shock</span>, especially for weak <span class="hlt">shocks</span> in relatively strong turbulence. We present results on this regime from <span class="hlt">shock</span>-resolving direct numerical simulations at a range of Reynolds and Mach numbers. Our focus is on the <span class="hlt">shock</span> structure and the effect on turbulence downstream of the <span class="hlt">shock</span>. We study the distribution of velocity gradients, in particular dilatation across the <span class="hlt">shock</span> and compare with theory available. We characterize turbulent <span class="hlt">shock</span> jumps which are found to depart from the laminar theory as they depend not only on the mean Mach number but also on the Reynolds and turbulent Mach number. Changes experienced by thermodynamic variables across the <span class="hlt">shock</span> will also be discussed. The authors gratefully acknowledge the support of AFOSR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MNRAS.463.1026L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MNRAS.463.1026L"><span id="translatedtitle">SHOCKFIND - an algorithm to identify magnetohydrodynamic <span class="hlt">shock</span> <span class="hlt">waves</span> in turbulent clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lehmann, Andrew; Federrath, Christoph; Wardle, Mark</p> <p>2016-11-01</p> <p>The formation of stars occurs in the dense molecular cloud phase of the interstellar medium. Observations and numerical simulations of molecular clouds have shown that supersonic magnetized turbulence plays a key role for the formation of stars. Simulations have also shown that a large fraction of the turbulent energy dissipates in <span class="hlt">shock</span> <span class="hlt">waves</span>. The three families of MHD <span class="hlt">shocks</span> - fast, intermediate and slow - distinctly <span class="hlt">compress</span> and heat up the molecular gas, and so provide an important probe of the physical conditions within a turbulent cloud. Here, we introduce the publicly available algorithm, SHOCKFIND, to extract and characterize the mixture of <span class="hlt">shock</span> families in MHD turbulence. The algorithm is applied to a three-dimensional simulation of a magnetized turbulent molecular cloud, and we find that both fast and slow MHD <span class="hlt">shocks</span> are present in the simulation. We give the first prediction of the mixture of turbulence-driven MHD <span class="hlt">shock</span> families in this molecular cloud, and present their distinct distributions of sonic and Alfvénic Mach numbers. Using subgrid one-dimensional models of MHD <span class="hlt">shocks</span> we estimate that ˜0.03 per cent of the volume of a typical molecular cloud in the Milky Way will be <span class="hlt">shock</span> heated above 50 K, at any time during the lifetime of the cloud. We discuss the impact of this <span class="hlt">shock</span> heating on the dynamical evolution of molecular clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016MNRAS.tmp.1134L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016MNRAS.tmp.1134L&link_type=ABSTRACT"><span id="translatedtitle">SHOCKFIND - An algorithm to identify magnetohydrodynamic <span class="hlt">shock</span> <span class="hlt">waves</span> in turbulent clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lehmann, Andrew; Federrath, Christoph; Wardle, Mark</p> <p>2016-08-01</p> <p>The formation of stars occurs in the dense molecular cloud phase of the interstellar medium. Observations and numerical simulations of molecular clouds have shown that supersonic magnetised turbulence plays a key role for the formation of stars. Simulations have also shown that a large fraction of the turbulent energy dissipates in <span class="hlt">shock</span> <span class="hlt">waves</span>. The three families of MHD <span class="hlt">shocks</span> - fast, intermediate and slow - distinctly <span class="hlt">compress</span> and heat up the molecular gas, and so provide an important probe of the physical conditions within a turbulent cloud. Here we introduce the publicly available algorithm, SHOCKFIND, to extract and characterise the mixture of <span class="hlt">shock</span> families in MHD turbulence. The algorithm is applied to a 3-dimensional simulation of a magnetised turbulent molecular cloud, and we find that both fast and slow MHD <span class="hlt">shocks</span> are present in the simulation. We give the first prediction of the mixture of turbulence-driven MHD <span class="hlt">shock</span> families in this molecular cloud, and present their distinct distributions of sonic and Alfvénic Mach numbers. Using subgrid one-dimensional models of MHD <span class="hlt">shocks</span> we estimate that ˜0.03 % of the volume of a typical molecular cloud in the Milky Way will be <span class="hlt">shock</span> heated above 50 K, at any time during the lifetime of the cloud. We discuss the impact of this <span class="hlt">shock</span> heating on the dynamical evolution of molecular clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4530210','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4530210"><span id="translatedtitle">Fractionated Repetitive Extracorporeal <span class="hlt">Shock</span> <span class="hlt">Wave</span> Therapy: A New Standard in <span class="hlt">Shock</span> <span class="hlt">Wave</span> Therapy?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kisch, Tobias; Sorg, Heiko; Forstmeier, Vinzent; Mailaender, Peter; Kraemer, Robert</p> <p>2015-01-01</p> <p>Background. ESWT has proven clinical benefit in dermatology and plastic surgery. It promotes wound healing and improves tissue regeneration, connective tissue disorders, and inflammatory skin diseases. However, a single treatment session or long intervals between sessions may reduce the therapeutic effect. The present study investigated the effects of fractionated repetitive treatment in skin microcirculation. Methods. 32 rats were randomly assigned to two groups and received either fractionated repetitive high-energy ESWT every ten minutes or placebo <span class="hlt">shock</span> <span class="hlt">wave</span> treatment, applied to the dorsal lower leg. Microcirculatory effects were continuously assessed by combined laser Doppler imaging and photospectrometry. Results. In experimental group, cutaneous tissue oxygen saturation was increased 1 minute after the first application and until the end of the measuring period at 80 minutes after the second treatment (P < 0.05). The third ESWT application boosted the effect to its highest extent. Cutaneous capillary blood flow showed a significant increase after the second application which was sustained for 20 minutes after the third application (P < 0.05). Placebo group showed no statistically significant differences. Conclusions. Fractionated repetitive extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy (frESWT) boosts and prolongs the effects on cutaneous hemodynamics. The results indicate that frESWT may provide greater benefits in the treatment of distinct soft tissue disorders compared with single-session ESWT. PMID:26273619</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023251','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023251"><span id="translatedtitle">Turbulence Modeling for <span class="hlt">Shock</span> <span class="hlt">Wave</span>/Turbulent Boundary Layer Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lillard, Randolph P.</p> <p>2011-01-01</p> <p>Accurate aerodynamic computational predictions are essential for the safety of space vehicles, but these computations are of limited accuracy when large pressure gradients are present in the flow. The goal of the current project is to improve the state of <span class="hlt">compressible</span> turbulence modeling for high speed flows with <span class="hlt">shock</span> <span class="hlt">wave</span> / turbulent boundary layer interactions (SWTBLI). Emphasis will be placed on models that can accurately predict the separated region caused by the SWTBLI. These flows are classified as nonequilibrium boundary layers because of the very large and variable adverse pressure gradients caused by the <span class="hlt">shock</span> <span class="hlt">waves</span>. The lag model was designed to model these nonequilibrium flows by incorporating history effects. Standard one- and two-equation models (Spalart Allmaras and SST) and the lag model will be run and compared to a new lag model. This new model, the Reynolds stress tensor lag model (lagRST), will be assessed against multiple wind tunnel tests and correlations. The basis of the lag and lagRST models are to preserve the accuracy of the standard turbulence models in equilibrium turbulence, when the Reynolds stresses are linearly related to the mean strain rates, but create a lag between mean strain rate effects and turbulence when nonequilibrium effects become important, such as in large pressure gradients. The affect this lag has on the results for SWBLI and massively separated flows will be determined. These computations will be done with a modified version of the OVERFLOW code. This code solves the RANS equations on overset grids. It was used for this study for its ability to input very complex geometries into the flow solver, such as the Space Shuttle in the full stack configuration. The model was successfully implemented within two versions of the OVERFLOW code. Results show a substantial improvement over the baseline models for transonic separated flows. The results are mixed for the SWBLI assessed. Separation predictions are not as good as the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.......219L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......219L"><span id="translatedtitle">Turbulence modeling for <span class="hlt">shock</span> <span class="hlt">wave</span>/turbulent boundary layer interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lillard, Randolph Pascal</p> <p></p> <p>Accurate aerodynamic computational predictions are essential for the safety of space vehicles, but these computations are of limited accuracy when large pressure gradients are present in the flow. The goal of the current project is to improve the state of <span class="hlt">compressible</span> turbulence modeling for high speed flows with <span class="hlt">shock</span> <span class="hlt">wave</span> / turbulent boundary layer interactions (SWTBLI). Emphasis is placed on models that can accurately predict the separated region caused by SWTBLI. These flows are classified as nonequilibrium boundary layers because of the very large and variable adverse pressure gradients caused by the <span class="hlt">shock</span> <span class="hlt">waves</span>. The Lag model was designed to model these nonequilibrium flows by incorporating history effects. Standard one- and two-equation models (Spalart Allmaras and SST) and the Lag model are run and compared to the new model. The focus of this work is thus to introduce a new model that builds on the success of the Lag model, but uses the Reynolds Stress Tensor (RST) as the lagged variable. This new model, the Reynolds stress tensor lag model (lagRST), is assessed against multiple wind tunnel tests and correlations as well as other models. The basis of the Lag and lagRST models is to preserve the accuracy of the standard turbulence models in equilibrium turbulence, when the Reynolds stresses are linearly related to the mean strain rates, but create a lag between mean strain rate effects and turbulence when nonequilibrium effects become important, such as in large pressure gradients. The effect this lag has on the results for SWTBLI and massively separated flows is determined. These computations are done with a modified version of the OVERFLOW code. This code solves the Reynolds Averaged Navier Stokes (RANS) equations on overset grids. It was used for this study for its ability to input very complex geometries into the flow solver, such as the Space Shuttle in the full stack configuration. The model was successfully implemented within two versions of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990063478','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990063478"><span id="translatedtitle">Numerical Simulation of Low-Density <span class="hlt">Shock-Wave</span> Interactions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glass, Christopher E.</p> <p>1999-01-01</p> <p>Computational Fluid Dynamics (CFD) numerical simulations of low-density <span class="hlt">shock-wave</span> interactions for an incident <span class="hlt">shock</span> impinging on a cylinder have been performed. Flow-field density gradient and surface pressure and heating define the type of interference pattern and corresponding perturbations. The maximum pressure and heat transfer level and location for various interaction types (i.e., <span class="hlt">shock-wave</span> incidence with respect to the cylinder) are presented. A time-accurate solution of the Type IV interference is employed to demonstrate the establishment and the steadiness of the low-density flow interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AIPC..706.1203T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AIPC..706.1203T"><span id="translatedtitle">Development of an Explosively Driven Sustained <span class="hlt">Shock</span> Generator for <span class="hlt">Shock</span> <span class="hlt">Wave</span> Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taylor, P.; Cook, I. T.; Salisbury, D. A.</p> <p>2004-07-01</p> <p>Investigation of explosive initiation phenomena close to the initiation threshold with explosively driven <span class="hlt">shock</span> <span class="hlt">waves</span> is difficult due to the attenuative nature of the pressure input. The design and experimental testing of a sustained <span class="hlt">shock</span> <span class="hlt">wave</span> generator based on an explosive plane <span class="hlt">wave</span> lens and impedance mismatched low density foam and high impedance layers is described. Calibration experiments to develop a 1-D calculational model for the plane <span class="hlt">wave</span> lens and booster charge were performed. A calculational study was undertaken to determine the sensitivity of the output pulse to plate and foam thicknesses and foam density. A geometry which generates a 24kb almost flat topped <span class="hlt">shock</span> <span class="hlt">wave</span> with a duration of over 4μs into the HMX based plastic explosive EDC37 was defined and tested. Experimental <span class="hlt">shock</span> profile data is compared with pre-shot predictions from the PETRA Eulerian hydrocode incorporating a "snowplough" or simple locking model for the foam. A reasonable match to the observed magnitude and profile of the initial <span class="hlt">shock</span> is achieved, although the timing of subsequent <span class="hlt">shock</span> <span class="hlt">waves</span> is less well matched.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JOM....65b.185A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JOM....65b.185A"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Waves</span> Impacting Composite Material Plates: The Mutual Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andreopoulos, Yiannis</p> <p>2013-02-01</p> <p>High-performance, fiber-reinforced polymer composites have been extensively used in structural applications in the last 30 years because of their light weight combined with high specific stiffness and strength at a rather low cost. The automotive industry has adopted these materials in new designs of lightweight vehicles. The mechanical response and characterization of such materials under transient dynamic loading caused with <span class="hlt">shock</span> impact induced by blast is not well understood. Air blast is associated with a fast traveling <span class="hlt">shock</span> front with high pressure across followed by a decrease in pressure behind due to expansion <span class="hlt">waves</span>. The time scales associated with the <span class="hlt">shock</span> front are typically 103 faster than those involved in the expansion <span class="hlt">waves</span>. Impingement of blast <span class="hlt">waves</span> on structures can cause a reflection of the <span class="hlt">wave</span> off the surface of the structure followed by a substantial transient aerodynamic load, which can cause significant deformation and damage of the structure. These can alter the overpressure, which is built behind the reflected <span class="hlt">shock</span>. In addition, a complex aeroelastic interaction between the blast <span class="hlt">wave</span> and the structure develops that can induce reverberation within an enclosure, which can cause substantial overpressure through multiple reflections of the <span class="hlt">wave</span>. Numerical simulations of such interactions are quite challenging. They usually require coupled solvers for the flow and the structure. The present contribution provides a physics-based analysis of the phenomena involved, a critical review of existing computational techniques together with some recent results involving face-on impact of <span class="hlt">shock</span> <span class="hlt">waves</span> on thin composite plates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790041960&hterms=technologie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtechnologie','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790041960&hterms=technologie&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtechnologie"><span id="translatedtitle">Plasma <span class="hlt">wave</span> turbulence associated with an interplanetary <span class="hlt">shock</span>. [<span class="hlt">wave</span> in solar wind upstream of magnetosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gurnett, D. A.; Neubauer, F. M.; Schwenn, R.</p> <p>1979-01-01</p> <p>The present paper deals with interplanetary <span class="hlt">shocks</span>, detected and analyzed to date, from the Helios 1 and 2 spacecraft in eccentric solar orbits. The plasma <span class="hlt">wave</span> turbulence associated with the <span class="hlt">shock</span> observed on March 30, 1976 is studied in detail. This event is of particular interest because it represents a clearly defined burst of turbulence against a quiet solar wind background both upstream and downstream of the <span class="hlt">shock</span>. The <span class="hlt">shock</span> itself is an oblique <span class="hlt">shock</span> with upstream parameters characterized by a low Mach number, a low beta, and an abnormally large electron to ion temperature ratio. The types of plasma <span class="hlt">wave</span> detected are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015ShWav.tmp...58S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015ShWav.tmp...58S&link_type=ABSTRACT"><span id="translatedtitle">Growth and decay of weak <span class="hlt">shock</span> <span class="hlt">waves</span> in magnetogasdynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, L. P.; Singh, D. B.; Ram, S. D.</p> <p>2015-12-01</p> <p>The purpose of the present study is to investigate the problem of the propagation of weak <span class="hlt">shock</span> <span class="hlt">waves</span> in an inviscid, electrically conducting fluid under the influence of a magnetic field. The analysis assumes the following two cases: (1) a planar flow with a uniform transverse magnetic field and (2) cylindrically symmetric flow with a uniform axial or varying azimuthal magnetic field. A system of two coupled nonlinear transport equations, governing the strength of a <span class="hlt">shock</span> <span class="hlt">wave</span> and the first-order discontinuity induced behind it, are derived that admit a solution that agrees with the classical decay laws for a weak <span class="hlt">shock</span>. An analytic expression for the determination of the <span class="hlt">shock</span> formation distance is obtained. How the magnetic field strength, whether axial or azimuthal, influences the <span class="hlt">shock</span> formation is also assessed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19720035837&hterms=waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dp%2Bwaves','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19720035837&hterms=waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dp%2Bwaves"><span id="translatedtitle">Radiative transfer effects on reflected <span class="hlt">shock</span> <span class="hlt">waves</span>. II - Absorbing gas.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Su, F. Y.; Olfe, D. B.</p> <p>1972-01-01</p> <p>Radiative cooling effects behind a reflected <span class="hlt">shock</span> <span class="hlt">wave</span> are calculated for an absorbing-emitting gas by means of an expansion procedure in the small density ratio across the <span class="hlt">shock</span> front. For a gray gas <span class="hlt">shock</span> layer with an optical thickness of order unity or less the absorption integral is simplified by use of the local temperature approximation, whereas for larger optical thicknesses a Rosseland diffusion type of solution is matched with the local temperature approximation solution. The calculations show that the <span class="hlt">shock</span> <span class="hlt">wave</span> will attenuate at first and then accelerate to a constant velocity. Under appropriate conditions the gas enthalpy near the wall may increase at intermediate times before ultimately decreasing to zero. A two-band absorption model yields end-wall radiant-heat fluxes which agree well with available <span class="hlt">shock</span>-tube measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040065781&hterms=harvard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dharvard','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040065781&hterms=harvard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dharvard"><span id="translatedtitle">The <span class="hlt">Shock</span> <span class="hlt">Compression</span> Laboratory at Harvard: A New Facility for Planetary Impact Processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stewart, S. T.</p> <p>2004-01-01</p> <p>The <span class="hlt">Shock</span> <span class="hlt">Compression</span> Laboratory in the Department of Earth and Planetary Sciences at Harvard is a new facility for the study of impact and collisional phenomena. The following describes the experimental capabilities of the laboratory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhFl...28h6101Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhFl...28h6101Z"><span id="translatedtitle">Reflection of cylindrical converging <span class="hlt">shock</span> <span class="hlt">wave</span> over a plane wedge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Fu; Si, Ting; Zhai, Zhigang; Luo, Xisheng; Yang, Jiming; Lu, Xiyun</p> <p>2016-08-01</p> <p>The cylindrical converging <span class="hlt">shock</span> reflection over a plane wedge is investigated experimentally and numerically in a specially designed <span class="hlt">shock</span> tube which converts a planar <span class="hlt">shock</span> into a cylindrical one. When the converging <span class="hlt">shock</span> is moving along the wedge, both the <span class="hlt">shock</span> strength and the incident angle are changing, which provides the possibility for the <span class="hlt">wave</span> transition. The results show that both regular reflection (RR) and Mach reflection (MR) are found on the wedge with different initial incident angles. The <span class="hlt">wave</span> transitions from direct Mach reflection (DiMR) to inverse Mach reflection (InMR) and further to transitioned regular reflection (TRR) are observed with appropriate initial incident angles. The instability development in the shear layer and strong vortices formation near the wall are evident, which are ascribed not only to the interaction of two shear layers but also to the <span class="hlt">shock</span> impact and the <span class="hlt">shock</span> converging effect. Because of the flow unsteadiness after the converging <span class="hlt">shock</span>, the detachment criterion provides a good estimation for the RR → MR transition, but fails to predict the DiMR → InMR transition, and MR is found to persist slightly below the mechanical equilibrium condition. A hysteresis process is found in the MR → TRR transition and becomes more apparent as the increase of the initial incident angle due to the <span class="hlt">shock</span> converging effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDD20001R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDD20001R"><span id="translatedtitle">Schlieren imaging of <span class="hlt">shock</span> <span class="hlt">waves</span> radiated by a trumpet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rendon, Pablo L.; Velasco-Segura, Roberto; Echeverria, Carlos; Porta, David; Vazquez, Teo; Perez-Lopez, Antonio; Stern, Catalina</p> <p>2014-11-01</p> <p>The flaring bell section of modern trumpets is known to be critical in determining a wide variety of properties associated with the sound radiated by these instruments. We are particularly interested in the shape of the radiated wavefront, which clearly depends on the bell profile. A horn loudspeaker is used to drive high-intensity sound at different frequencies through a B-flat concert trumpet. The sound intensity is high enough to produce <span class="hlt">shock</span> <span class="hlt">waves</span> inside the instrument resonator, and the radiated <span class="hlt">shocks</span> are then visualised using Schlieren imaging. Through these images we are able to study the geometry of the <span class="hlt">shock</span> <span class="hlt">waves</span> radiated by the instrument bell, and also to calculate their propagation speed. The results show that propagation outside the bell is very nearly spherical, and that, as expected, the frequency of the driving signal affects the point at which the <span class="hlt">shock</span> <span class="hlt">waves</span> separate from the instrument. We acknowledge financial support from PAPIIT IN109214 and PAPIIT IN117712.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015shw2.conf..855Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015shw2.conf..855Y"><span id="translatedtitle">Development of a Novel <span class="hlt">Shock</span> <span class="hlt">Wave</span> Catheter Ablation System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yamamoto, H.; Hasebe, Yuhi; Kondo, Masateru; Fukuda, Koji; Takayama, Kazuyoshi; Shimokawa, Hiroaki</p> <p></p> <p>Although radio-frequency catheter ablation (RFCA) is quite effective for the treatment tachyarrhythmias, it possesses two fundamental limitations, including limited efficacy for the treatment of ventricular tachyarrhythmias of epicardial origin and the risk of thromboembolism. Consequently, new method is required, which can eradicate arrhythmia source in deep part of cardiac muscle without heating. On the other hand, for a medical application of <span class="hlt">shock</span> <span class="hlt">waves</span>, extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripter (ESWL) has been established [1]. It was demonstrated that the underwater <span class="hlt">shock</span> focusing is one of most efficient method to generate a controlled high pressure in a small region [2]. In order to overcome limitations of existing methods, we aimed to develop a new catheter ablation system with underwater <span class="hlt">shock</span> <span class="hlt">waves</span> that can treat myocardium at arbitrary depth without causing heat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AmJPh..74.1071O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AmJPh..74.1071O"><span id="translatedtitle">The role of <span class="hlt">shock</span> <span class="hlt">waves</span> in expansion tube accelerators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olson, G.; Peterson, Richard; Pulford, B.; Seaberg, M.; Stein, K.; Stelter, C.; Weber, R.</p> <p>2006-12-01</p> <p>Simulations are combined with laboratory measurements to show the important role of <span class="hlt">shock</span> <span class="hlt">waves</span> in a popular physics demonstration, the "ping pong cannon." The simulation and measurements confirm a developing <span class="hlt">shock</span> <span class="hlt">wave</span> that reflects from the end of the closed tube and approaching ball and the eventual formation of a transient localized pressure build-up near the exit tape barrier. This 2atm burst of pressure peaks within a few microseconds of the ball's arrival, resulting from the combination of near ambient gas density and <span class="hlt">shock</span> heating to about 1200K. Pulsed schlieren images beyond the exit confirm the sequence of internally reflected <span class="hlt">shock</span> <span class="hlt">waves</span> and the intense, hot air pressure pulse that explosively removes the exit tape just prior to the ball arrival.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5462554','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5462554"><span id="translatedtitle">Attenuation of <span class="hlt">shock</span> <span class="hlt">waves</span> in copper and stainless steel</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harvey, W.B.</p> <p>1986-06-01</p> <p>By using <span class="hlt">shock</span> pins, data were gathered on the trajectories of <span class="hlt">shock</span> <span class="hlt">waves</span> in stainless steel (SS-304L) and oxygen-free-high-conductivity copper (OFHC-Cu). <span class="hlt">Shock</span> 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 <span class="hlt">shock</span> pressures generated in the steel experiments were approximately 109, 130, and 147 GPa and in the copper experiments, the peak <span class="hlt">shock</span> pressures were approximately 111, 132, and 143 GPa. In each experiment, an attenuation of the <span class="hlt">shock</span> <span class="hlt">wave</span> by a following release <span class="hlt">wave</span> was clearly observed. An extensive effort using two characteristic codes (described in this work) to theoretically calculate the attenuation of the <span class="hlt">shock</span> <span class="hlt">waves</span> was made. The efficacy of several different constitutive equations to successfully model the experiments was studied by comparing the calculated <span class="hlt">shock</span> 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 <span class="hlt">shock</span> <span class="hlt">waves</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750050112&hterms=Anatomy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DAnatomy','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750050112&hterms=Anatomy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DAnatomy"><span id="translatedtitle">The anatomy of floating <span class="hlt">shock</span> fitting. [<span class="hlt">shock</span> <span class="hlt">waves</span> computation for flow field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Salas, M. D.</p> <p>1975-01-01</p> <p>The floating <span class="hlt">shock</span> fitting technique is examined. Second-order difference formulas are developed for the computation of discontinuities. A procedure is developed to compute mesh points that are crossed by discontinuities. The technique is applied to the calculation of internal two-dimensional flows with arbitrary number of <span class="hlt">shock</span> <span class="hlt">waves</span> and contact surfaces. A new procedure, based on the coalescence of characteristics, is developed to detect the formation of <span class="hlt">shock</span> <span class="hlt">waves</span>. Results are presented to validate and demonstrate the versatility of the technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22324692','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22324692"><span id="translatedtitle">Dispersive nature of high mach number collisionless plasma <span class="hlt">shocks</span>: Poynting flux of oblique whistler <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sundkvist, David; Krasnoselskikh, V; Bale, S D; Schwartz, S J; Soucek, J; Mozer, F</p> <p>2012-01-13</p> <p>Whistler <span class="hlt">wave</span> trains are observed in the foot region of high Mach number quasiperpendicular <span class="hlt">shocks</span>. The <span class="hlt">waves</span> are oblique with respect to the ambient magnetic field as well as the <span class="hlt">shock</span> normal. The Poynting flux of the <span class="hlt">waves</span> is directed upstream in the <span class="hlt">shock</span> normal frame starting from the ramp of the <span class="hlt">shock</span>. This suggests that the <span class="hlt">waves</span> are an integral part of the <span class="hlt">shock</span> structure with the dispersive <span class="hlt">shock</span> as the source of the <span class="hlt">waves</span>. These observations lead to the conclusion that the <span class="hlt">shock</span> ramp structure of supercritical high Mach number <span class="hlt">shocks</span> is formed as a balance of dispersion and nonlinearity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22252090','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22252090"><span id="translatedtitle">Traveling <span class="hlt">waves</span> in Hall-magnetohydrodynamics and the ion-acoustic <span class="hlt">shock</span> structure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hagstrom, George I.; Hameiri, Eliezer</p> <p>2014-02-15</p> <p>Hall-magnetohydrodynamics (HMHD) is a mixed hyperbolic-parabolic partial differential equation that describes the dynamics of an ideal two fluid plasma with massless electrons. We study the only <span class="hlt">shock</span> <span class="hlt">wave</span> family that exists in this system (the other discontinuities being contact discontinuities and not <span class="hlt">shocks</span>). We study planar traveling <span class="hlt">wave</span> solutions and we find solutions with discontinuities in the hydrodynamic variables, which arise due to the presence of real characteristics in Hall-MHD. We introduce a small viscosity into the equations and use the method of matched asymptotic expansions to show that solutions with a discontinuity satisfying the Rankine-Hugoniot conditions and also an entropy condition have continuous <span class="hlt">shock</span> structures. The lowest order inner equations reduce to the <span class="hlt">compressible</span> Navier-Stokes equations, plus an equation which implies the constancy of the magnetic field inside the <span class="hlt">shock</span> structure. We are able to show that the current is discontinuous across the <span class="hlt">shock</span>, even as the magnetic field is continuous, and that the lowest order outer equations, which are the equations for traveling <span class="hlt">waves</span> in inviscid Hall-MHD, are exactly integrable. We show that the inner and outer solutions match, which allows us to construct a family of uniformly valid continuous composite solutions that become discontinuous when the diffusivity vanishes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JPhB...48q5301W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JPhB...48q5301W&link_type=ABSTRACT"><span id="translatedtitle">Dynamics of <span class="hlt">shock</span> <span class="hlt">waves</span> in a superfluid unitary Fermi gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wen, Wen; Shui, Tiankun; Shan, Yafei; Zhu, Changping</p> <p>2015-09-01</p> <p>We study the formation and dynamics of <span class="hlt">shock</span> <span class="hlt">waves</span> initiated by a repulsive potential in a superfluid unitary Fermi gas by using the order-parameter equation. In the theoretical framework, the regularization process of <span class="hlt">shock</span> <span class="hlt">waves</span> mediated by the quantum pressure term is purely dispersive. Our results show good agreement with the experiment of Joseph et al (2011 Phys. Rev. Lett. 106 150401). We reveal that the boxlike-shaped density peak observed in the experiment consists of many vortex rings due to the transverse instability of the dispersive <span class="hlt">shock</span> <span class="hlt">wave</span>. In addition, we study the transition from a sound <span class="hlt">wave</span> to subsonic <span class="hlt">shock</span> <span class="hlt">waves</span> as the strength of the repulsive potential increases and show a strong qualitative change in the propagation speed of the wavefronts. For a relatively small strength of the repulsive potential, the propagation speed decreases below the sound speed with the increase of the strength as a scaling behavior. For a large strength where the <span class="hlt">shock</span> <span class="hlt">waves</span> are formed by colliding two spatially separated clouds, the speed is still smaller than the sound speed, but remains almost unchanged as the strength increases, which can be interpreted as the same expansion speed of the proliferation of the vortex rings originated from the transverse instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhFl...20a6104K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhFl...20a6104K"><span id="translatedtitle">Head-on collision of <span class="hlt">shock</span> <span class="hlt">wave</span> induced vortices with solid and perforated walls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kontis, K.; An, R.; Zare-Behtash, H.; Kounadis, D.</p> <p>2008-01-01</p> <p>An experimental study has been conducted to examine the interaction of <span class="hlt">shock</span> <span class="hlt">wave</span> induced vortices with a flat plate and a perforated plate. The experiments were carried out using a 30mm internal diameter <span class="hlt">shock</span>-tube at Mach numbers 1.31, 1.49, and 1.61 under critical driver conditions. Air was used both in the driver and driven sections. High-speed schlieren photography was employed to study the flow development and the resulting interactions with the plates. Wall pressure measurements on both plates were also carried out in order to study the flow interactions quantitatively. The experimental results indicated that a region of strong flow development is generated near the wall surface, due to the flow interactions of reflected <span class="hlt">waves</span> and oncoming induced vortices. This flow behavior causes the generation of multiple pressure fluctuations on the wall. In the case of the perforated plate, a weaker initial reflected <span class="hlt">wave</span> is produced, which is followed by <span class="hlt">compression</span> <span class="hlt">waves</span>, due to the internal reflections within the plate. The transmitted <span class="hlt">wave</span> is reduced in strength, compared to the initial incident <span class="hlt">shock</span> <span class="hlt">wave</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MNRAS.428.1643P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MNRAS.428.1643P"><span id="translatedtitle">Cosmological <span class="hlt">shock</span> <span class="hlt">waves</span>: clues to the formation history of haloes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Planelles, Susana; Quilis, Vicent</p> <p>2013-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> developed during the formation and evolution of cosmic structures are key features encoding crucial information on the hierarchical formation of the Universe. We present the analysis of an Eulerian adaptive mesh refinement hydrodynamical and N-body simulation in a Λ cold dark matter cosmology especially focused on the study of cosmological <span class="hlt">shock</span> <span class="hlt">waves</span>. The combination of a <span class="hlt">shock</span>-capturing algorithm together with the use of a halo finder allows us to study the morphological structures of the <span class="hlt">shock</span> patterns, the statistical properties of <span class="hlt">shocked</span> cells and the correlations between the cosmological <span class="hlt">shock</span> <span class="hlt">waves</span> appearing at different scales and the properties of the haloes harbouring them. According to their localization with respect to the population of haloes in the simulation, <span class="hlt">shocks</span> can be split into two broad classes: internal weak <span class="hlt">shocks</span> related with evolutionary events within haloes and external strong <span class="hlt">shocks</span> associated with large-scale events. The <span class="hlt">shocks</span>' segregation according to their characteristic sizes is also visible in the <span class="hlt">shock</span> distribution function. This function contains information on the abundances and strength of the different <span class="hlt">shocks</span>, and it can be fitted by a double power law with a break in the slope around a Mach number of 20. We introduce a generalized scaling relation that correlates the average Mach numbers within the virial radius of haloes and their virial masses. In this plane, Mach number-virial mass, two well-differentiated regimes appear. Haloes occupy different areas of such plane according to their early evolutionary histories: those haloes with a relatively quiet evolution have an almost constant Mach number independently of their masses, whereas haloes undergoing significant merger events very early in their evolution show a linear dependence on their masses. At high redshift, the distribution of haloes in this plane forms an L-like pattern that evolves with time, bending the vertical branch towards the horizontal one. We</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010226','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010226"><span id="translatedtitle">Hybrid Simulation of the <span class="hlt">Shock</span> <span class="hlt">Wave</span> Trailing the Moon</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Israelevich, P.; Ofman, Leon</p> <p>2012-01-01</p> <p>A standing <span class="hlt">shock</span> <span class="hlt">wave</span> behind the Moon was predicted by Michel (1967) but never observed nor simulated. We use 1D hybrid code in order to simulate the collapse of the plasma-free cavity behind the Moon and for the first time to model the formation of this <span class="hlt">shock</span>. Starting immediately downstream of the obstacle we consider the evolution of plasma expansion into the cavity in the frame of reference moving along with the solar wind. Well-known effects as electric charging of the cavity affecting the plasma flow and counterstreaming ion beams in the wake are reproduced. Near the apex of the inner Mach cone where the plasma flows from the opposite sides of the obstacle meet, a <span class="hlt">shock</span> <span class="hlt">wave</span> arises. We expect the <span class="hlt">shock</span> to be produced at periods of high electron temperature solar wind streams (T(sub i) much less than T(sub e) approximately 100 eV). The <span class="hlt">shock</span> is produced by the interaction of oppositely directed proton beams in the plane containing solar wind velocity and interplanetary magnetic field vectors. In the direction across the magnetic field and the solar wind velocity, the <span class="hlt">shock</span> results from the interaction of the plasma flow with the region of the enhanced magnetic field inside the cavity that plays the role of the magnetic barrier. The appearance of the standing <span class="hlt">shock</span> <span class="hlt">wave</span> is expected at the distance of approximately 7R(sub M) downstream of the Moon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhFl...28e6102S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhFl...28e6102S"><span id="translatedtitle">Plane <span class="hlt">shock</span> <span class="hlt">wave</span> interaction with a cylindrical water column</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sembian, S.; Liverts, M.; Tillmark, N.; Apazidis, N.</p> <p>2016-05-01</p> <p>A complex system of <span class="hlt">waves</span> propagating inside a water column due to the impact of plane <span class="hlt">shock</span> <span class="hlt">wave</span> is investigated both experimentally and numerically. Flow features, such as, focusing of expansion <span class="hlt">waves</span> generating large negative pressure, nucleation of cavitation bubbles, and a re-circulation zone are observed and discussed qualitatively and quantitatively. Experiments are conducted on a 22 mm diametrical water column hit by <span class="hlt">shock</span> <span class="hlt">waves</span> with Mach numbers 1.75 and 2.4 in a newly constructed exploding wire facility. A new technique to create a properly shaped, repeatable, large diameter water column with straight walls is presented. Qualitative features of the flow are captured using the shadowgraph technique. With the aid of numerical simulations the <span class="hlt">wave</span> motions inside the column are analyzed; the spatial location of the expansion <span class="hlt">wave</span> focusing point and the corresponding negative peak pressures is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26382524','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26382524"><span id="translatedtitle">Passage of a <span class="hlt">shock</span> <span class="hlt">wave</span> through inhomogeneous media and its impact on gas-bubble deformation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nowakowski, A F; Ballil, A; Nicolleau, F C G A</p> <p>2015-08-01</p> <p>The paper investigates <span class="hlt">shock</span>-induced vortical flows within inhomogeneous media of nonuniform thermodynamic properties. Numerical simulations are performed using a Eulerian type mathematical model for <span class="hlt">compressible</span> multicomponent flow problems. The model, which accounts for pressure nonequilibrium and applies different equations of state for individual flow components, shows excellent capabilities for the resolution of interfaces separating <span class="hlt">compressible</span> fluids as well as for capturing the baroclinic source of vorticity generation. The developed finite volume Godunov type computational approach is equipped with an approximate Riemann solver for calculating fluxes and handles numerically diffused zones at flow component interfaces. The computations are performed for various initial conditions and are compared with available experimental data. The initial conditions promoting a <span class="hlt">shock</span>-bubble interaction process include weak to high planar <span class="hlt">shock</span> <span class="hlt">waves</span> with a Mach number ranging from 1.2 to 3 and isolated cylindrical bubble inhomogeneities of helium, argon, nitrogen, krypton, and sulphur hexafluoride. The numerical results reveal the characteristic features of the evolving flow topology. The impulsively generated flow perturbations are dominated by the reflection and refraction of the <span class="hlt">shock</span>, the <span class="hlt">compression</span>, and acceleration as well as the vorticity generation within the medium. The study is further extended to investigate the influence of the ratio of the heat capacities on the interface deformation. PMID:26382524</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6824056','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6824056"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span> as turbulent mix amplifiers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buckingham, A.C.</p> <p>1988-06-09</p> <p>In our initial studies of the shockwave-turbulence interaction process we emphasized the apparent enhancement a pre-existing turbulent field induced by <span class="hlt">shock</span> passage. The present investigations are concerned with the possibly significant changes induced in <span class="hlt">shock</span>-front structure during interactions with turbulence. The <span class="hlt">shock</span> front may be diffracted; its initially planar surface may deform into a wrinkled or corrugated pattern; or it may break up into a succession of wavelets. A crucial question is whether or not the shockwave remains a sharp discontinuity albeit randomly wrinkled or corrugated by interaction with random perturbations in density, velocity, and/or pressure associated with the downstream turbulence. An additional question concerns the time of influence exerted by the shockwave in redistribution of turbulence. At some point, the apparent enhancement ceases and the turbulence decays to pre-existing levels. Geometrical distortions at the front alter the mean flow strain pattern influencing the persistence of duration of this <span class="hlt">shock</span> interaction/turbulent enhancement process after passage of the <span class="hlt">shock</span> front well downstream of the interaction region. Examination and description of the influence of these alterations to shockwave structure during <span class="hlt">shock</span>-turbulence interaction are the basic themes of this work. 6 refs., 4 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22217874','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22217874"><span id="translatedtitle">A comparative study on <span class="hlt">shock</span> <span class="hlt">compression</span> of nanocrystalline Al and Cu: <span class="hlt">Shock</span> profiles and microscopic views of plasticity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ma, Wen; Hou, Yong; Zhu, Wenjun</p> <p>2013-10-28</p> <p><span class="hlt">Shock</span> <span class="hlt">compressions</span> of nanocrystalline (nc) metals Al and Cu with the same grain size and texture are studied by using molecular dynamics simulations. Results have revealed that the <span class="hlt">shock</span> front of both Al and Cu can be divided into three stages: elastic, grain-boundary-mediated, and dislocation-mediated plastic deformation. The transition planes among these three stages are proven to be non-planar by two-dimensional <span class="hlt">shock</span> response analysis, including local stress, shear, temperature, and atom configuration. The difference between <span class="hlt">shocked</span> Al and Cu is that the rise rate of the elastic stage of Cu is slightly higher than that of Al, and that the <span class="hlt">shock</span>-front width of Al is wider than Cu at the same loading conditions. For the plastic stage, the dislocation density of <span class="hlt">shocked</span> Al is lower than Cu, and the contribution of grain-boundary-mediated plasticity to <span class="hlt">shock</span> front and strain for nc Al is more pronounced than for nc Cu. These results are explained through intrinsic material properties and atomistic analysis of the plastic process. In the case of the <span class="hlt">shocked</span> Al sample, partial dislocations, perfect dislocations, and twins are observed, but few evidence of perfect dislocations and twins are observed in the <span class="hlt">shocked</span> Cu.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhPl...20h2303R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhPl...20h2303R"><span id="translatedtitle">Arbitrary amplitude solitary and <span class="hlt">shock</span> <span class="hlt">waves</span> in an unmagnetized quantum dusty electron-positron-ion plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rouhani, M. R.; Akbarian, A.; Mohammadi, Z.</p> <p>2013-08-01</p> <p>The behavior of quantum dust ion acoustic soliton and <span class="hlt">shocks</span> in a plasma including inertialess quantum electrons and positrons, classical cold ions, and stationary negative dust grains are studied, using arbitrary amplitude approach. The effect of dissipation due to viscosity of ions is taken into account. The numerical analysis of Sagdeev potential for small value of quantum diffraction parameter (H) shows that for chosen plasma, only <span class="hlt">compressive</span> solitons can exist and the existence domain of this type of solitons is decreased by increasing dust density (d). Additionally, the possibility of propagation of both subsonic and supersonic <span class="hlt">compressive</span> solitons is investigated. It is shown that there is a critical dust density above which only supersonic solitons are observed. Moreover, increasing d leads to a reduction in the existence domain of <span class="hlt">compressive</span> solitons and the possibility of propagation of rarefactive soliton is provided. So, rarefactive solitons are observed only due to the presence of dust particles in this model quantum plasma. Furthermore, numerical solution of governed equations for arbitrary amplitude <span class="hlt">shock</span> <span class="hlt">waves</span> has been investigated. It is shown that only <span class="hlt">compressive</span> large amplitude <span class="hlt">shocks</span> can propagate. Finally, the effects of plasma parameters on these structures are investigated. This research will be helpful in understanding the properties of dense astrophysical (i.e., white dwarfs and neutron stars) and laboratory dusty plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22227890','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22227890"><span id="translatedtitle">Arbitrary amplitude solitary and <span class="hlt">shock</span> <span class="hlt">waves</span> in an unmagnetized quantum dusty electron-positron-ion plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rouhani, M. R.; Akbarian, A.; Mohammadi, Z.</p> <p>2013-08-15</p> <p>The behavior of quantum dust ion acoustic soliton and <span class="hlt">shocks</span> in a plasma including inertialess quantum electrons and positrons, classical cold ions, and stationary negative dust grains are studied, using arbitrary amplitude approach. The effect of dissipation due to viscosity of ions is taken into account. The numerical analysis of Sagdeev potential for small value of quantum diffraction parameter (H) shows that for chosen plasma, only <span class="hlt">compressive</span> solitons can exist and the existence domain of this type of solitons is decreased by increasing dust density (d). Additionally, the possibility of propagation of both subsonic and supersonic <span class="hlt">compressive</span> solitons is investigated. It is shown that there is a critical dust density above which only supersonic solitons are observed. Moreover, increasing d leads to a reduction in the existence domain of <span class="hlt">compressive</span> solitons and the possibility of propagation of rarefactive soliton is provided. So, rarefactive solitons are observed only due to the presence of dust particles in this model quantum plasma. Furthermore, numerical solution of governed equations for arbitrary amplitude <span class="hlt">shock</span> <span class="hlt">waves</span> has been investigated. It is shown that only <span class="hlt">compressive</span> large amplitude <span class="hlt">shocks</span> can propagate. Finally, the effects of plasma parameters on these structures are investigated. This research will be helpful in understanding the properties of dense astrophysical (i.e., white dwarfs and neutron stars) and laboratory dusty plasmas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=208737','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=208737"><span id="translatedtitle"><span class="hlt">Shock-wave</span> cosmology inside a black hole</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Smoller, Joel; Temple, Blake</p> <p>2003-01-01</p> <p>We construct a class of global exact solutions of the Einstein equations that extend the Oppeheimer–Snyder model to the case of nonzero pressure, inside the black hole, by incorporating a <span class="hlt">shock</span> <span class="hlt">wave</span> at the leading edge of the expansion of the galaxies, arbitrarily far beyond the Hubble length in the Friedmann–Robertson–Walker (FRW) spacetime. Here the expanding FRW universe emerges be-hind a subluminous blast <span class="hlt">wave</span> that explodes outward from the FRW center at the instant of the big bang. The total mass behind the <span class="hlt">shock</span> decreases as the <span class="hlt">shock</span> <span class="hlt">wave</span> expands, and the entropy condition implies that the <span class="hlt">shock</span> <span class="hlt">wave</span> must weaken to the point where it settles down to an Oppenheimer–Snyder interface, (bounding a finite total mass), that eventually emerges from the white hole event horizon of an ambient Schwarzschild spacetime. The entropy condition breaks the time symmetry of the Einstein equations, selecting the explosion over the implosion. These <span class="hlt">shock-wave</span> solutions indicate a cosmological model in which the big bang arises from a localized explosion occurring inside the black hole of an asymptotically flat Schwarzschild spacetime. PMID:12972640</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Sound%2Bwaves%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860026497&hterms=Sound+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Sound%2Bwaves%2529"><span id="translatedtitle">Cylindrical sound <span class="hlt">wave</span> generated by <span class="hlt">shock</span>-vortex interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ribner, H. S.</p> <p>1985-01-01</p> <p>The passage of a columnar vortex broadside through a <span class="hlt">shock</span> is investigated. This has been suggested as a crude, but deterministic, model of the generation of '<span class="hlt">shock</span> noise' by the turbulence in supersonic jets. The vortex is decomposed by Fourier transform into plane sinusoidal shear <span class="hlt">waves</span> disposed with radial symmetry. The plane sound <span class="hlt">waves</span> produced by each shear <span class="hlt">wave/shock</span> interaction are recombined in the Fourier integral. The <span class="hlt">waves</span> possess an envelope that is essentially a growing cylindrical sound <span class="hlt">wave</span> centered at the transmitted vortex. The pressure jump across the nominal radius R = ct attenuates with time as 1/(square root of R) and varies around the arc in an antisymmetric fashion resembling a quadrupole field. Very good agreement, except near the <span class="hlt">shock</span>, is found with the antisymmetric component of reported interferometric measurements in a <span class="hlt">shock</span> tube. Beyond the front r approximately equals R is a precursor of opposite sign, that decays like 1/R, generated by the 1/r potential flow around the vortex core. The present work is essentially an extension and update of an early approximate study at M = 1.25. It covers the range (R/core radius) = 10, 100, 1000, and 10,000 for M = 1.25 and (in part) for M = 1.29 and, for fixed (R/core radius) = 1000, the range M = 1.01 to infinity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1503....2K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1503....2K"><span id="translatedtitle">Effects of low-dose extracorporeal <span class="hlt">shock</span> <span class="hlt">waves</span> on microcirculation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khaled, Walaa; Goertz, Ole; Lauer, Henrik; Lehnhardt, Marcus; Hauser, Jörg</p> <p>2012-11-01</p> <p>The extended wounds of burn patients remain a challenge due to wound infection and following septicemia. The aim of this study was to analyze microcirculation, angiogenesis and leukocyte endothelium interaction after burn injury with and without extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> application (ESWA). A novel shockwave system was developed based on a commercially available device for orthopedics (Dornier Aries®) that was equipped with a newly developed applicator. This system is based on the electromagnetic <span class="hlt">shock</span> <span class="hlt">wave</span> emitter (EMSE) technology and was introduced to accomplish a localized treatment for wound healing. The system includes a novel field of focus for new applications, with high precision and ease of use. In the animal study, full-thickness burns were inflicted on to the ears of hairless mice (n=51). Intravital fluorescent microscopy was used to assess microcirculatory parameters, angiogenesis and leukocyte behavior. ESWA was performed on day 1, 3 and 7. Values were obtained immediately after burn, as well as at days 1, 3, 7, and 12 post burn. All shockwave treated groups showed an accelerated angiogenesis with a less non-perfused area and an improved blood flow after burn injury compared to the placebo control group. After three treatments, the <span class="hlt">shock</span> <span class="hlt">waves</span> increased the number of rolling leukocytes significantly compared to the non-treated animals. <span class="hlt">Shock</span> <span class="hlt">waves</span> seem to have a positive effect on several parameters of wound healing after burn injury. However, further investigations are necessary to detect positive influence of <span class="hlt">shock</span> <span class="hlt">waves</span> on microcirculation after burn injuries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ASAJ..114.2463W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ASAJ..114.2463W"><span id="translatedtitle">Treatment of nonunions of long bone fractures with <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Ching-Jen</p> <p>2003-10-01</p> <p>A prospective clinical study investigated the effectiveness of <span class="hlt">shock</span> <span class="hlt">waves</span> in the treatment of 72 patients with 72 nonunions of long bone fractures (41 femurs, 19 tibias, 7 humeri, 1 radius, 3 ulnas and 1 metatarsal). The doses of <span class="hlt">shock</span> <span class="hlt">waves</span> were 6000 impulses at 28 kV for the femur and tibia, 3000 impulses at 28 kV for the humerus, 2000 impulses at 24 kV for the radius and ulna, and 1000 impulses at 20 kV for the metatarsal. The results of treatment were assessed clinically, and fracture healing was assessed with plain x-rays and tomography. The rate of bony union was 40% at 3 months, 60.9% at 6 months and 80% at 12 months followup. <span class="hlt">Shock</span> <span class="hlt">wave</span> treatment was most successful in hypertrophic nonunions and nonunions with a defect and was least effective in atrophic nonunions. There were no systemic complications or device-related problems. Local complications included petechiae and hematoma formation that resolved spontaneously. In the author's experience, the results of the <span class="hlt">shock</span> <span class="hlt">wave</span> treatment were similar to the results of surgical treatment for chronic nonunions with no surgical risks. <span class="hlt">Shock</span> <span class="hlt">wave</span> treatment is a safe and effective alternative method in the treatment of chronic nonunions of long bones.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.653a2045P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.653a2045P"><span id="translatedtitle">Numerical investigations of <span class="hlt">shock</span> <span class="hlt">wave</span> propagation in polymethylmethacrylate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Popova, T. V.; Mayer, A. E.; Khishchenko, K. V.</p> <p>2015-11-01</p> <p>Using the Maxwell model of viscoelastic medium, we numerically investigate the influence of the viscoelastic properties of polymethylmethacrylate on the variation of the <span class="hlt">shock</span> <span class="hlt">wave</span> amplitude with depth. Parameters of the Maxwell model are chosen by comparison with experimental data on the high-speed impact of plates in order to fit the modeling results with the experimentally measured profiles of the free-surface velocity. A caloric equation of state is used to calculate the pressure from density and internal energy. It is shown that at the limit of weak <span class="hlt">shock</span> <span class="hlt">waves</span>, the accounting of the viscoelastic properties allows one to achieve a better agreement between calculated and experimental data for the magnitude of the <span class="hlt">shock</span> <span class="hlt">wave</span> velocity in comparison with the case of hydrodynamic calculations. Using the viscoelastic and hydrodynamic approaches, we investigated the dynamics of <span class="hlt">shock</span> <span class="hlt">waves</span> in polymethylmethacrylate initiated by micro-, nano- and picosecond pulses of pressure on the sample surface. The calculation results show that the changes in the <span class="hlt">shock</span> <span class="hlt">wave</span> amplitude with depth are approximately identical in the hydrodynamic and viscoelastic cases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003ASAJ..114.2453S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003ASAJ..114.2453S"><span id="translatedtitle">Regulatory standards and calibration procedures for <span class="hlt">shock</span> <span class="hlt">wave</span> devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schafer, Mark E.</p> <p>2003-10-01</p> <p>In order to bring any <span class="hlt">shock</span> <span class="hlt">wave</span> device into commercial use, i.e., clinical practice, it must receive regulatory approval from either the U.S Food and Drug Administration (FDA) or the appropriate national agency. A key part of this process involves the complete temporal and spatial description of the <span class="hlt">shock</span> <span class="hlt">wave</span> field. This device characterization presents a number of formidable measurement challenges, principally due to the destructive effects of <span class="hlt">shock</span> <span class="hlt">waves</span> on the measurement sensor, and <span class="hlt">shock</span> <span class="hlt">wave</span> variability (especially for electrohydraulic systems). This presentation reviews the measurement and regulatory approaches used for characterizing <span class="hlt">shock</span> <span class="hlt">wave</span> devices, including FDA and international measurement standards. The current approach is a compromise between the desire for a complete characterization of all possible parameters, and the realities of making the measurements. The complete measurement process will be described, including equipment, procedures and pitfalls. Polyvinylidene Fluoride (PVDF) membrane hydrophones have been the key enabling technology, providing sufficient temporal bandwidth and minimal effective sensor area, all at reasonable cost. Other types of sensors, both good and bad, have been used for these measurements. The talk will also present case studies of measurements of several lithotripters measured over the last 15 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25655309','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25655309"><span id="translatedtitle">Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment harms developing chicken embryos.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kiessling, Maren C; Milz, Stefan; Frank, Hans-Georg; Korbel, Rüdiger; Schmitz, Christoph</p> <p>2015-02-06</p> <p>Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment (rESWT) has became one of the best investigated treatment modalities for cellulite, including the abdomen as a treatment site. Notably, pregnancy is considered a contraindication for rESWT, and concerns have been raised about possible harm to the embryo when a woman treated with rESWT for cellulite is not aware of her pregnancy. Here we tested the hypothesis that rESWT may cause serious physical harm to embryos. To this end, chicken embryos were exposed in ovo to various doses of radial <span class="hlt">shock</span> <span class="hlt">waves</span> on either day 3 or day 4 of development, resembling the developmental stage of four- to six-week-old human embryos. We found a dose-dependent increase in the number of embryos that died after radial <span class="hlt">shock</span> <span class="hlt">wave</span> exposure on either day 3 or day 4 of development. Among the embryos that survived the <span class="hlt">shock</span> <span class="hlt">wave</span> exposure a few showed severe congenital defects such as missing eyes. Evidently, our data cannot directly be used to draw conclusions about potential harm to the embryo of a pregnant woman treated for cellulite with rESWT. However, to avoid any risks we strongly recommend applying radial <span class="hlt">shock</span> <span class="hlt">waves</span> in the treatment of cellulite only if a pregnancy is ruled out.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ShWav..25..283G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ShWav..25..283G"><span id="translatedtitle">A study of slipstreams in triple <span class="hlt">shock</span> <span class="hlt">wave</span> configurations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gvozdeva, L.; Gavrenkov, S.; Nesterov, A.</p> <p>2015-05-01</p> <p>A <span class="hlt">shock</span> <span class="hlt">wave</span> appearing in supersonic gas flow reflects in different ways depending on flow conditions. It can take the form of regular or irregular reflection. For the irregular reflection configuration of three <span class="hlt">shock</span> <span class="hlt">waves</span> and a slipstream arises. Mathematical investigations of the development of parameters across slipstream in triple <span class="hlt">shock</span> configuration have been made with variation of the angle of incidence of the <span class="hlt">shock</span> <span class="hlt">wave</span>, the <span class="hlt">shock</span> <span class="hlt">wave</span> Mach number and the adiabatic index of the gas. It has been shown that the characteristic mixing parameters of the slipstream increase with the increase of Mach number of the flow and the decrease of the heat capacity ratio. This leads to an increase of vortex formation and an increase of the angular spread of the slipstream. It also has been shown that the angle between the reflected <span class="hlt">wave</span> and the slipstream diminishes with the decrease in heat capacity ratio so that the value may become of the same order as the spread angle. This may lead to quantitative changes in the whole reflection pattern near the triple point. The evident dependence of slipstream instability magnitude on the physical and chemical transformation intensity in the fluid was previously experimentally observed. The results of an analytical investigation appeared to be in good agreement with the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4319177','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4319177"><span id="translatedtitle">Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment harms developing chicken embryos</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kiessling, Maren C.; Milz, Stefan; Frank, Hans-Georg; Korbel, Rüdiger; Schmitz, Christoph</p> <p>2015-01-01</p> <p>Radial extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> treatment (rESWT) has became one of the best investigated treatment modalities for cellulite, including the abdomen as a treatment site. Notably, pregnancy is considered a contraindication for rESWT, and concerns have been raised about possible harm to the embryo when a woman treated with rESWT for cellulite is not aware of her pregnancy. Here we tested the hypothesis that rESWT may cause serious physical harm to embryos. To this end, chicken embryos were exposed in ovo to various doses of radial <span class="hlt">shock</span> <span class="hlt">waves</span> on either day 3 or day 4 of development, resembling the developmental stage of four- to six-week-old human embryos. We found a dose-dependent increase in the number of embryos that died after radial <span class="hlt">shock</span> <span class="hlt">wave</span> exposure on either day 3 or day 4 of development. Among the embryos that survived the <span class="hlt">shock</span> <span class="hlt">wave</span> exposure a few showed severe congenital defects such as missing eyes. Evidently, our data cannot directly be used to draw conclusions about potential harm to the embryo of a pregnant woman treated for cellulite with rESWT. However, to avoid any risks we strongly recommend applying radial <span class="hlt">shock</span> <span class="hlt">waves</span> in the treatment of cellulite only if a pregnancy is ruled out. PMID:25655309</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..SHK.B6005Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..SHK.B6005Z"><span id="translatedtitle">The effect of phase transition on the failure behaviors of PZT 95/5 under <span class="hlt">shock</span> <span class="hlt">compression</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Fuping; He, Hongliang; Liu, Gaomin; Liu, Yusheng</p> <p>2013-06-01</p> <p>PZT 95/5 ferroelectric ceramics has been utilized for the use in <span class="hlt">shock</span> driven pulsed power supplies for many years. In previous studying, the low impendence failure layer had been confirmed in PZT 95/5 when the <span class="hlt">shock</span> pressure is up to 2.4 GPa. But to the <span class="hlt">shock</span> <span class="hlt">compression</span> of the poled PZT 95/5, the failure behavior of this material is still unknown. In this paper, the failure behaviors of axially poled PZT 95/5 have been tested by measuring the particle velocity of the rear free surface at different pressures. Results show that the failure layer exists in poled PZT 95/5 when the <span class="hlt">shock</span> pressure reaches 2.4 GPa. Through analysis the velocity profile of free surface, which shows that the velocity of failure layer is the same as the <span class="hlt">shock-wave</span> speed and the delay time decreases with increasing the <span class="hlt">shock</span> stress. Comparing the failure behaviors of unpoled PZT 95/5, it finds that the threshold pressure and the velocity of failure layer are the same, but the delay time in poled PZT 95/5 is slight higher than that in unpoled PZT 95/5. The FE to AFE phase transition has been suggested to explain the increase of the delay time in poled PZT 95/5.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1195.1395H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1195.1395H"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Compression</span> and Recovery of Microorganism-Loaded Broths and AN Emulsion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hazell, P. J.; Beveridge, C.; Groves, K.; Stennett, C.</p> <p>2009-12-01</p> <p>The microorganisms Escherichia coli, Enterococcus faecalis and Zygosaccharomyces bailii and an oil-based emulsion, have been subjected to <span class="hlt">shock</span> <span class="hlt">compression</span> using the flyer-plate technique to initial pressures of 0.8 GPa (in the suspension). In each experiment, a stainless steel capsule was used to contain the broths and allow for recovery without contamination. Where cavitation was mostly suppressed by virtue of simultaneous <span class="hlt">shock</span> and dynamic <span class="hlt">compression</span>, no kill was observed. By introducing an air gap behind the suspension, limited kill was measured in the yeast. Results also suggest that stable emulsification occurs in coarse oil-based emulsions that are subjected to <span class="hlt">shock</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhyU...50..333F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhyU...50..333F"><span id="translatedtitle">ORAL ISSUE OF THE JOURNAL "USPEKHI FIZICHESKIKH NAUK": Intense <span class="hlt">shock</span> <span class="hlt">waves</span> and extreme states of matter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fortov, Vladimir E.</p> <p>2007-04-01</p> <p>The physical properties of hot dense matter over a broad domain of the phase diagram are of immediate interest in astrophysics, planetary physics, power engineering, controlled thermonuclear fusion, impulse technologies, enginery, and several special applications. The use of intense <span class="hlt">shock</span> <span class="hlt">waves</span> in dynamic physics and high-pressure chemistry has made the exotic high-energy-density states of matter a subject of laboratory experiments and enabled advancing by many orders of magnitude along the pressure scale to range into the megabars and even gigabars. The present report reviews the latest experimental research involving <span class="hlt">shock</span> <span class="hlt">waves</span> in nonideal plasmas under conditions of strong collective interparticle interaction. The results of investigations into the thermodynamic, transport, and optical properties of strongly <span class="hlt">compressed</span> hot matter, as well as into its composition and conductivity, are discussed. Experimental techniques for high energy density cumulation, the drivers of intense <span class="hlt">shock</span> <span class="hlt">waves</span>, and methods for the fast diagnostics of high-energy plasma are considered. Also discussed are <span class="hlt">compression</span>-stimulated physical effects: pressure-induced ionization, plasma phase transitions, the deformation of bound states, plasma blooming ('transparentization' of plasma), etc. Suggestions for future research are put forward.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6525673','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6525673"><span id="translatedtitle">Plane <span class="hlt">shock</span> <span class="hlt">wave</span> studies of Westerly granite and Nugget sandstone</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Larson, D.B.; Anderson, G.D.</p> <p>1980-12-01</p> <p>Plane <span class="hlt">shock</span> <span class="hlt">wave</span> experiments were performed by using a light-gas gun on dry and water-saturated Westerly granite and dry Nugget sandstone. Changes in the slopes of the <span class="hlt">shock</span> velocity versus particle velocity curves at 2 to 3 GPa and 1 to 2 GPa for dry granite and for dry sandstone, respectively, are attributed to the onset of pore collapse. However, there is little apparent loss of shear strength in either dry rock over the stress range of the experiments (i.e., 9.3 GPa in Westerly granite and 9.2 GPa in Nugget sandstone). Agreement between the <span class="hlt">shock</span> <span class="hlt">wave</span> data and quasistatic, uniaxial strain data for the dry rock implies the absence of rate-dependence in uniaxial strain. The <span class="hlt">shock</span> data on saturated granite agree well with those for dry granite, thus suggesting there was no loss in shear strength as a result of pore pressure buildup.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750033814&hterms=blast+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dblast%2Bwaves','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750033814&hterms=blast+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dblast%2Bwaves"><span id="translatedtitle">Hypersonic flows generated by parabolic and paraboloidal <span class="hlt">shock</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schwartz, L. W.</p> <p>1974-01-01</p> <p>A computer algorithm has been developed to determine the blunt-body flowfields supporting symmetric parabolic and paraboloidal <span class="hlt">shock</span> <span class="hlt">waves</span> at infinite free-stream Mach number. Solutions are expressed in an analytic form as high-order power series, in the coordinate normal to the <span class="hlt">shock</span>, whose coefficients can be determined exactly. Analytic continuation is provided by the use of Pade approximations. Test cases provide solutions of very high accuracy. In the axisymmetric case for gamma equals 715 the solution has been found far downstream, where it agrees with the modified blast-<span class="hlt">wave</span> results. For plane flow, on the other hand, a limit line appears within the <span class="hlt">shock</span> layer, a short distance past the sonic line, suggesting the presence of an imbedded <span class="hlt">shock</span>. Local solutions in the downstream limit are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvD..94b5004L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvD..94b5004L"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span>, rarefaction <span class="hlt">waves</span>, and nonequilibrium steady states in quantum critical systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lucas, Andrew; Schalm, Koenraad; Doyon, Benjamin; Bhaseen, M. J.</p> <p>2016-07-01</p> <p>We reexamine the emergence of a universal nonequilibrium steady state following a local quench between quantum critical heat baths in spatial dimensions greater than one. We show that energy transport proceeds by the formation of an instantaneous <span class="hlt">shock</span> <span class="hlt">wave</span> and a broadening rarefaction <span class="hlt">wave</span> on either side of the interface, and not by two <span class="hlt">shock</span> <span class="hlt">waves</span> as previously proposed. For small temperature differences the universal steady state energy currents of the two-<span class="hlt">shock</span> and rarefaction-<span class="hlt">shock</span> solutions coincide. Over a broad range of parameters, the difference in the energy flow across the interface between these two solutions is at the level of 2%. The properties of the energy flow remain fully universal and independent of the microscopic theory. We briefly discuss the width of the <span class="hlt">shock</span> <span class="hlt">wave</span> in a viscous fluid, the effects of momentum relaxation, and the generalization to charged fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5834827','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5834827"><span id="translatedtitle"><span class="hlt">Compressibility</span> and cyclotron damping in the oblique Alfven <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harmon, J.K. )</p> <p>1989-11-01</p> <p><span class="hlt">Compressibility</span>, magnetic <span class="hlt">compressibility</span>, and damping rate are calculated for the obliquely propagating Alfven shear <span class="hlt">wave</span> in high- and low-beta Vlasov plasmas. There is an overall increase in <span class="hlt">compressibility</span> as beta is reduced from {beta} = 1 to {beta}{much lt}1. For high obliquity {theta} and low frequency ({omega} {much lt} {Omega}{sub p}) the <span class="hlt">compressibility</span> C follows a k{sup 2} <span class="hlt">wave</span> number dependence; for high {theta} and low {beta} the approximation C(k) {approx} k{sub n}{sup 2} {identical to} (kV{sub A}/{Omega}{sub p}){sup 2} holds for <span class="hlt">wave</span> numbers up to the proton cyclotron resonance, where {Omega}{sub p} is the proton cyclotron frequency and V{sub A} is the Alfven velocity. Strong proton cyclotron damping sets in at k{sub n} of the order of unity; the precise k{sub n} position of the damping cutoff increases with decreasing {beta} and increasing {theta}. Hence <span class="hlt">compressibility</span> can exceed unity near the damping cutoff for high-{theta} <span class="hlt">waves</span> in a low-{beta} plasma. The magnetic <span class="hlt">compressibility</span> of the oblique Alfven <span class="hlt">wave</span> also has a k{sup 2} dependence and can reach a maximum value of the order of 10% at high <span class="hlt">wave</span> number. It is shown that Alfven <span class="hlt">compressibility</span> could be the dominant contributor to the near-Sun solar wind density fluctuation spectrum for k>10{sup {minus}2} km{sup {minus}1} and hence might cause some of the flattening at high <span class="hlt">wave</span> number seen in radio scintillation measurements. This would also be consistent with the notion that the observed density spectrum inner scale is a signature of cyclotron damping.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17837616','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17837616"><span id="translatedtitle">Nonequilibrium molecular motion in a hypersonic <span class="hlt">shock</span> <span class="hlt">wave</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pham-Van-Diep, G; Erwin, D; Muntz, E P</p> <p>1989-08-11</p> <p>Molecular velocities have been measured inside a hypersonic, normal <span class="hlt">shock</span> <span class="hlt">wave</span>, where the gas experiences rapid changes in its macroscopic properties. As first hypothesized by Mott-Smith, but never directly observed, the molecular velocity distribution exhibits a qualitatively bimodal character that is derived from the distribution functions on either side of the <span class="hlt">shock</span>. Quantitatively correct forms of the molecular velocity distribution function in highly nonequilibrium flows can be calculated, by means of the Direct Simulation Monte Carlo technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5648733','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5648733"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">waves</span>, increase of entropy and loss of information</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lax, P.D.</p> <p>1984-10-01</p> <p>We discuss, for the simplified model of a single conservation law, the concepts of genuine nonlinearity, breakdown of classical solutions, solutions in the distribution sense and their nonuniqueness, the viscosity method, finite difference methods, and the <span class="hlt">shock</span> condition. We then discuss, for the scalar model, the compactness of solutions constructed by the viscosity and difference methods, and derive the entropy inequality for such solutions. We derive Glimm's estimate for the total variation of solutions of scalar equations that satisfy the <span class="hlt">shock</span> condition, and show that a discontinuous solution that satisfies the <span class="hlt">shock</span> condition also satisfies the entropy condition. Scattered remarks are given about the equations of <span class="hlt">compressible</span> flow: the increase of entropy, some consequences of Carnot's theorem, and the equipartition of energy in the wake of strong <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007APS..SHK.C6002A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007APS..SHK.C6002A"><span id="translatedtitle">A study of reactant interfaces in Ni+Al particle systems during <span class="hlt">shock</span> <span class="hlt">wave</span> propagation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Austin, Ryan A.; McDowell, David L.; Horie, Yasuyuki; Benson, David J.</p> <p>2007-06-01</p> <p>Macro-scale responses of energetic materials during <span class="hlt">shock</span> <span class="hlt">compression</span> are influenced strongly by thermo-mechano-chemical processes occurring at the level of the microstructure. For example, it is believed that the propagation of chemical reactions in reactive particle systems is intimately linked to conditions at reactant interfaces such as surface temperature, phase changes, defect density, and mass mixing due to inelastic deformation. To provide explicit resolution of such interfacial conditions, numerical models are constructed. The finite element method is used to numerically solve the differential equations that govern the coupled thermomechanical response of micron-size particle mixtures of Ni and Al during <span class="hlt">shock</span> <span class="hlt">wave</span> propagation (interface chemistry is not yet modeled). The size and temperature distributions of contiguous reactant contact surfaces are quantified for a range of <span class="hlt">shock</span> strengths. A parametric study of mixture attributes is undertaken to assess the sensitivity of the aforementioned distributions to variations of the microstructure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900006569','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900006569"><span id="translatedtitle">Flow separation in <span class="hlt">shock</span> <span class="hlt">wave</span> boundary layer interactions at hypersonic speeds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hamed, A.</p> <p>1990-01-01</p> <p>An assessment is presented for the experimental data on separated flow in <span class="hlt">shock</span> <span class="hlt">wave</span> turbulent boundary layer interactions at hypersonic and supersonic speeds. The data base consists mainly of two dimensional and axisymmetric interactions in <span class="hlt">compression</span> corners or cylinder-flares, and externally generated oblique <span class="hlt">shock</span> interactions with boundary layers over flat plates or cylindrical surfaces. The conditions leading to flow separation and the subsequent changes in the flow empirical correlations for incipient separation are reviewed. The effects of the Mach number, Reynolds number, surface cooling and the methods of detecting separation are discussed. The pertinent experimental data for the separated flow characteristics in separated turbulent boundary layer <span class="hlt">shock</span> interaction are also presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820008935','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820008935"><span id="translatedtitle">A <span class="hlt">shock</span> <span class="hlt">wave</span> approach to the noise of supersonic propellers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dittmar, J. H.; Rice, E. J.</p> <p>1981-01-01</p> <p>To model propeller noise expected for a turboprop aircraft, the pressure ratio across the <span class="hlt">shock</span> at the propeller tip was calculated and compared with noise data from three propellers. At helical tip Mach numbers over 1.0, using only the tip <span class="hlt">shock</span> <span class="hlt">wave</span>, the model gave a fairly good prediction of the noise for a bladed propeller and for a propeller swept for aerodynamic purposes. However for another propeller, which was highly swept and designed to have noise cancellations from the inboard propeller sections, the <span class="hlt">shock</span> strength from the tip over predicted the noise. In general the good agreement indicates that <span class="hlt">shock</span> theory is a viable method for predicting the noise from these supersonic propellers but that the <span class="hlt">shock</span> strengths from all of the blade sections need to be properly included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730015974','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730015974"><span id="translatedtitle">Ion streaming instabilities with application to collisionless <span class="hlt">shock</span> <span class="hlt">wave</span> structure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Golden, K. I.; Linson, L. M.; Mani, S. A.</p> <p>1973-01-01</p> <p>The electromagnetic dispersion relation for two counterstreaming ion beams of arbitrary relative strength flowing parallel to a dc magnetic field is derived. The beams flow through a stationary electron background and the dispersion relation in the fluid approximation is unaffected by the electron thermal pressure. The dispersion relation is solved with a zero net current condition applied and the regions of instability in the k-U space (U is the relative velocity between the two ion beams) are presented. The parameters are then chosen to be applicable for parallel <span class="hlt">shocks</span>. It was found that unstable <span class="hlt">waves</span> with zero group velocity in the <span class="hlt">shock</span> frame can exist near the leading edge of the <span class="hlt">shock</span> for upstream Alfven Mach numbers greater than 5.5. It is suggested that this mechanism could generate sufficient turbulence within the <span class="hlt">shock</span> layer to scatter the incoming ions and create the required dissipation for intermediate strength <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982Natur.300..237M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982Natur.300..237M"><span id="translatedtitle">Measurements on a <span class="hlt">shock</span> <span class="hlt">wave</span> generated by a solar flare</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maxwell, A.; Dryer, M.</p> <p>1982-11-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by intense solar flares may be driven by a large amount of ejected mass, about 5 x 10 to the 16th g, and the total energy involved may be of the order of 10 to the 32nd erg. The <span class="hlt">shocks</span> may have initial velocities of the order of 2,000 km/s and, in their exodus through the corona, may be accompanied by fast-moving optical transients, the emission of highly characteristic radio signatures and the acceleration of particles to quasi-relativistic velocities. Here, a review is presented of data on a high-velocity <span class="hlt">shock</span> generated by a flare on 18 August 1979, 1400 UT, and comments are provided on some previously deduced velocities for the <span class="hlt">shock</span>. Attention is given to a model, based on current computer programs to account for the overall characteristics of the <span class="hlt">shock</span> as it propagated through the corona and the interplanetary plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830033736&hterms=Exodus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DExodus','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830033736&hterms=Exodus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DExodus"><span id="translatedtitle">Measurements on a <span class="hlt">shock</span> <span class="hlt">wave</span> generated by a solar flare</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Maxwell, A.; Dryer, M.</p> <p>1982-01-01</p> <p><span class="hlt">Shock</span> <span class="hlt">waves</span> generated by intense solar flares may be driven by a large amount of ejected mass, about 5 x 10 to the 16th g, and the total energy involved may be of the order of 10 to the 32nd erg. The <span class="hlt">shocks</span> may have initial velocities of the order of 2,000 km/s and, in their exodus through the corona, may be accompanied by fast-moving optical transients, the emission of highly characteristic radio signatures and the acceleration of particles to quasi-relativistic velocities. Here, a review is presented of data on a high-velocity <span class="hlt">shock</span> generated by a flare on 18 August 1979, 1400 UT, and comments are provided on some previously deduced velocities for the <span class="hlt">shock</span>. Attention is given to a model, based on current computer programs to account for the overall characteristics of the <span class="hlt">shock</span> as it propagated through the corona and the interplanetary plasma.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5969536','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5969536"><span id="translatedtitle">Single-pulse coherent Raman spectroscopy in <span class="hlt">shock-compressed</span> benzene</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moore, D.S.; Schmidt, S.C.; Schiferl, D.; Shaner, J.W.</p> <p>1983-01-01</p> <p>Single-pulse backwards stimulated Raman and reflected broadband coherent anti-Stokes Raman spectroscopy (BSRC and RBBCARS) have been used to measure the vibrational frequency shifts of the 992 cm/sup -1/ ring-stretching mode of liquid benzene <span class="hlt">shock-compressed</span> to pressures up to 1.2 GPa. The resulting shifts of approx. 7.5 cm/sup -1//GPa in the dynamic experiments are compared to spontaneous Raman-scattering measurements of heated samples <span class="hlt">compressed</span> in a diamond-anvil cell. RBBCARS was used to simultaneously measure the ring-stretching mode vibrational frequencies of liquid benzene/liquid perdeuterobenzene mixtures <span class="hlt">shock-compressed</span> to pressures up to 1.53 GPa. Additional experiments that demonstrate the difficulty of using polarization-sensitive coherent Raman techniques, such as Raman-induced Kerr effect spectroscopy (RIKES), in <span class="hlt">shock-compressed</span> samples are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1773k0017V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1773k0017V"><span id="translatedtitle">Hybrid numerical model of <span class="hlt">shock</span> <span class="hlt">waves</span> in collisionless plasma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vshivkova, L.; Dudnikova, G.; Vshivkov, K.</p> <p>2016-10-01</p> <p>We present a 2D hybrid numerical plasma model of generation and structure of collisionless <span class="hlt">shock</span> <span class="hlt">waves</span> in plasma and ion acceleration on their front considering physical processes in supernova remnant <span class="hlt">shock</span> precursor. In modeling a <span class="hlt">shock</span> <span class="hlt">wave</span> is generated by sending a supersonic flow against a reflecting wall. The consequent interaction between incoming and reflected plasma flows lead to formation of <span class="hlt">waves</span>, the structure of which depends on a flow velocity. The hybrid approach reduces the computational expenses relative to a fully kinetic one, and on the other hand, permits to model ions with a greater accuracy than the magnetohydrodynamics (MHD) allows. Also, another important advantage of the hybrid approach is the possibility to study the important instabilities on an ion time scale, neglecting the modes associated with electrons. In the current work a new computational scheme where stability condition allows carry out computations on more wide set of computational and physical parameters is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870035148&hterms=blast+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dblast%2Bwaves','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870035148&hterms=blast+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dblast%2Bwaves"><span id="translatedtitle">Numerical simulation of <span class="hlt">shock</span> <span class="hlt">wave</span> diffraction by TVD schemes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Young, Victor Y. C.; Yee, H. C.</p> <p>1987-01-01</p> <p>An upwind total variation diminishing (TVD) scheme and a predictor-corrector symmetric TVD scheme were used to numerically simulate the blast <span class="hlt">wave</span> diffraction on a stationary object. The objective is to help design an optimum configuration so that lateral motion is minimized and at the same time vortex shedding and flow separation are reduced during a blast <span class="hlt">wave</span> encounter. Results are presented for a generic configuration for both a coarse grid and a fine grid to illustrate the global and local diffraction flow fields. Numerical experiments for the <span class="hlt">shock</span> <span class="hlt">wave</span> reflection on a wedge are also included to validate the current approach. Numerical study indicated that these TVD schemes are more stable and produced higher <span class="hlt">shock</span> resolution than classical <span class="hlt">shock</span> capturing methods such as the explicit MacCormack scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990AIPC..208..831L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990AIPC..208..831L"><span id="translatedtitle">Air bubble-<span class="hlt">shock</span> <span class="hlt">wave</span> interaction adjacent to gelantine surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lush, P. A.; Tomita, Y.; Onodera, O.; Takayama, K.; Sanada, N.; Kuwahara, M.; Ioritani, N.; Kitayama, O.</p> <p>1990-07-01</p> <p>The interaction between a <span class="hlt">shock</span> <span class="hlt">wave</span> and an air bubble-adjacent to a gelatine surface is investigated in order to simulate human tissue damage resulting from extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> lithotripsy. Using high speed cine photography it is found that a <span class="hlt">shock</span> <span class="hlt">wave</span> of strength 11 MPa causes 1-3 mm diameter bubbles to produce high velocity microjets with penetration rates of approximately 110 m/s and penetration depths approximately equal to twice the initial bubble diameter. Theoretical considerations for liquid impact on soft solid of similar density indicate that microjet velocities will be twice the penetration rate, i.e. 220 m/s in the present case. Such events are the probable cause of observed renal tissue damage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980223576','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980223576"><span id="translatedtitle">Effect of Surface Roughness on Characteristics of Spherical <span class="hlt">Shock</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Huber, Paul W.; McFarland, Donald R.</p> <p>1959-01-01</p> <p>Measurements of peak overpressure and Mach stem height were made at four burst heights. Data were obtained with instrumentation capable of directly observing the variation of <span class="hlt">shock</span> <span class="hlt">wave</span> movement with time. Good similarity of free air <span class="hlt">shock</span> peak overpressure with larger scale data was found to exist. The net effect of surface roughness on <span class="hlt">shock</span> peak overpressures slightly. Surface roughness delayed the Mach stem formation at the greatest charge height and lowered the growth at all burst heights. A similarity parameter was found which approximately correlates the triple point path at different burst heights.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860041641&hterms=ohms+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dohms%2Blaw','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860041641&hterms=ohms+law&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dohms%2Blaw"><span id="translatedtitle">Hybrid simulation codes with application to <span class="hlt">shocks</span> and upstream <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Winske, D.</p> <p>1985-01-01</p> <p>Hybrid codes in which part of the plasma is represented as particles and the rest as a fluid are discussed. In the past few years such codes with particle ions and massless, fluid electrons have been applied to space plasmas, especially to collisionless <span class="hlt">shocks</span>. All of these simulation codes are one-dimensional and similar in structure, except for how the field equations are solved. The various approaches that are used (resistive Ohm's law, predictor-corrector, Hamiltonian) are described in detail and results from the various codes are compared with examples taken from collisionless <span class="hlt">shocks</span> and low frequency <span class="hlt">wave</span> phenomena upstream of <span class="hlt">shocks</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20662072','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20662072"><span id="translatedtitle">A physical mechanism of nonthermal plasma effect on <span class="hlt">shock</span> <span class="hlt">wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kuo, S.P.; Kuo, Steven S.</p> <p>2005-01-01</p> <p>An electric discharge is applied to generate a plasma spike in front of a wedge. Use of this plasma spike to modify the <span class="hlt">shock</span> <span class="hlt">wave</span> structure in a supersonic flow over the wedge is then studied. It is shown that the plasma spike can effectively deflect the incoming flow before the flow reaches the wedge; consequently, the <span class="hlt">shock</span> structure in the interaction region is modified from an oblique to a curved shape. Moreover, the <span class="hlt">shock</span> becomes detached as the strength of the plasma spike exceeds a critical level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=treated+water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtreated%2Bwater','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000086187&hterms=treated+water&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtreated%2Bwater"><span id="translatedtitle">Far-Infrared Water Emissions from Magnetohydrodynamic <span class="hlt">Shock</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaufman, Michael J.; Neufeld, David A.</p> <p>1996-01-01</p> <p>Nondissociative, magnetohydrodynamic, C-type <span class="hlt">shock</span> <span class="hlt">waves</span> are expected to be a prodigious source of far-infrared water emissions in dense interstellar regions. We have constructed a model to calculate the farinfrared H20 line spectra that emerge from such <span class="hlt">shocks</span>. Using the best estimates currently available for the radiative cooling rate and the degree of ion-neutral coupling within the <span class="hlt">shocked</span> gas, we modeled the temperature structure of MHD <span class="hlt">shocks</span> using standard methods in which the charged and neutral particles are treated separately as two weakly coupled, interpenetrating fluids. Then we solved the equations of statistical equilibrium to find the populations of the lowest 179 and 170 rotational states of ortho- and para-H2O We have completed an extensive parameter study to determine the emergent H2O line luminosities as a function of preshock density in the range n(H2) equals 10(exp 4) - 10(sup 6.5)/cc and <span class="hlt">shock</span> velocity in the range upsilon(sub s) = 5 - 40 km/ s. We find that numerous rotational transitions of water are potentially observable using the Infrared Space Observatory and the Submillimeter <span class="hlt">Wave</span> Astronomy Satellite and may be used as diagnostics of the <span class="hlt">shocked</span> gas. We have also computed the rotational and ro-vibrational emissions expected from H2, CO, and OH, and we discuss how complementary observations of such emissions may be used to further constrain the <span class="hlt">shock</span> conditions. In common with previous studies, we come close to matching the observed H2, and high-J CO emissions from the Orion-KL star-forming region on the basis of a single <span class="hlt">shock</span> model. We present our predictions for the strengths of H2O line emission from the Orion <span class="hlt">shock</span>, and we show how our results may be scaled to other regions where molecular <span class="hlt">shocks</span> are likely to be present.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFD.F1077T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFD.F1077T"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> mitigation using Newtonian and non-Newtonian fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tao, Xingtian; Colvert, Brendan; Eliasson, Veronica</p> <p>2014-11-01</p> <p>The effectiveness of a wall of liquid as a blast mitigation device is examined using a <span class="hlt">shock</span> tube and a custom-designed and -built <span class="hlt">shock</span> test chamber. High-speed schlieren photography and high-frequency pressure sensors allow measurement during the relevant <span class="hlt">shock</span> interaction time periods of the liquid-gas interface. The characteristic quantities that reflect these effects include reflected-to-incident <span class="hlt">shock</span> strength ratio, transmitted-to-incident <span class="hlt">shock</span> strength ratio, transmitted and reflected impulse, and peak pressure reduction. In particular, the effects of viscous properties of the fluid are considered when using non-Newtonian dilatant and pseudoplastic fluids. Experiments have been performed with both Newtonian and non-Newtonian fluids. The impact of a <span class="hlt">shock</span> <span class="hlt">waves</span> on Non-newtonian fluids is compared to that of Newtonian fluids. Experiments show that non-Newtonian fluids have very strong reflection properties, acting like solid walls under the impact of a <span class="hlt">shock</span> <span class="hlt">wave</span>. Further work is to be performed to compare quantitatively the properties of Newtonian vs. non-Newtonian fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993MsT..........7F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993MsT..........7F"><span id="translatedtitle">Mitigation of <span class="hlt">shock</span> <span class="hlt">waves</span> in a cylindrical tunnel by foam</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fondaw, Grant W.</p> <p>1993-03-01</p> <p>The effectiveness of foam linings in mitigating <span class="hlt">shock</span> <span class="hlt">waves</span> in tunnels is investigated. A polyurethane foam liner of varying density, crush strength, and thickness was modeled inside a 1 meter radius tunnel and an explosion of 1.25 kg of plastic explosive was simulated. Using CTH, an Eulerian-Lagrangian hydrodynamics code from Sandia National Laboratories, the overpressures were computed and compared graphically to determine the effect of varying each foam parameter. The walls of the tunnel consisted of a perfectly reflecting boundary, and in some cases, a foam liner. Low density foam provided the most <span class="hlt">shock</span> attenuation, with a 20 cm thick layer of 90% void 0.1265 g/cm(sup 3) foam reducing the <span class="hlt">shock</span> overpressure by 70% at 50 meters. The effects of foam thickness on the <span class="hlt">shock</span> pressure varied with the distance from the explosion. The thicker foams raised the initial pressure near the explosion due to constriction of the tunnel area. However, the thicker layers reduced the <span class="hlt">shock</span> faster. Varying the crush strength of the foam from 1 atm to 3 atm overpressure did not affect its ability to mitigate <span class="hlt">shock</span> propagation in the tunnel. The results strongly suggest that foam can mitigate <span class="hlt">shock</span> <span class="hlt">waves</span> significantly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JAP...115b4904S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JAP...115b4904S&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">compression</span> behavior of bi-material powder composites with disparate melting temperatures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sullivan, Kyle T.; Swift, Damian; Barham, Matthew; Stölken, James; Kuntz, Joshua; Kumar, Mukul</p> <p>2014-01-01</p> <p>Laser driven experiments were used to investigate the <span class="hlt">shock</span> <span class="hlt">compression</span> behavior of powder processed Bismuth/Tungsten (Bi/W) composite samples. The constituents provide different functionality to the composite behavior as Bi could be <span class="hlt">shock</span> melted at the pressures attained in this work, while the W could not. Samples were prepared by uniaxial pressing, and the relative density was measured as a function of particle size, applied pressure, and composition for both hot and cold pressing conditions. This resulted in sample densities between 73% and 99% of the theoretical maximum density, and also noticeable differences in microstructure in the hot and cold pressed samples. The <span class="hlt">compression</span> <span class="hlt">waves</span> were generated with a 1.3 × 1.3 mm square spot directly onto the surface of the sample, using irradiances between 1012 and 1013 W/cm2, which resulted in calculated peak pressures between 50 and 150 GPa within a few micrometers. Sample recovery and post-mortem analysis revealed the formation of a crater on the laser drive surface, and the depth of this crater corresponded to the depth to which the Bi had been melted. The melt depth was found to be primarily a function of residual porosity and composition, and ranged from 167 to 528 μm. In general, a higher porosity led to a larger melt depth. Direct numerical simulations were performed, and indicated that the observed increase in melt depth for low-porosity samples could be largely attributed to increased heating associated with work done for pore collapse. However, the relative scaling was sensitive to composition, with low volume fraction Bi samples exhibiting a much stronger dependence on porosity than high Bi content samples. Select samples were repeated using an Al foil ablator, but there were no noticeable differences ensuring that the observed melting was indeed pressure-driven and was not a result of direct laser heating. The resultant microstructures and damage near the spall surface were also investigated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10183615','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10183615"><span id="translatedtitle">Characteristics of <span class="hlt">shock-compressed</span> configuration of Ti and Si powder mixtures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Thadhani, N.N.; Dunbar, E.; Graham, R.A.</p> <p>1993-08-01</p> <p><span class="hlt">Shock-compression</span> recovery experiments were performed on mixtures of Ti and Si powders of fine, medium, and coarse morphology, and packed at different initial densities, using the Sandia Momma and Poppa Bear fixtures with Baratol explosive. The <span class="hlt">shock-compressed</span> configuration revealed characteristics typical of either chemically reacted material with fine equiaxed grains, or unreacted material with densely packed Ti and Si particles. The unreacted configuration showed that Ti particles were extensively deformed, irrespective of powder morphology and <span class="hlt">shock</span> conditions generated by either fixture. In contrast Si particles showed different characteristics depending on the powder morphology, packing density, and <span class="hlt">shock</span> conditions. The microstructural characteristics of unreacted configuration of Ti and Si powder mixtures were investigated. Mechanistic processes occurring prior to the inception of <span class="hlt">shock</span>-induced chemical reactions in this system are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MS%26E..146a2019H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MS%26E..146a2019H"><span id="translatedtitle">Multiple <span class="hlt">shock</span> <span class="hlt">compressions</span> in tri-amino-tri-nitro-benzene based energetic materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hussain, T.; Yan, L.; Huang, F.</p> <p>2016-08-01</p> <p>Various hazard and vulnerability scenarios for energetic materials involve multiple <span class="hlt">shock</span> <span class="hlt">compression</span>. Triaminotrinitrobenzene (TATB) based explosives are comparatively insensitive to <span class="hlt">shocks</span> of low impacts and therefore considered suitable materials for the devices vulnerable to low <span class="hlt">shock</span> impacts. Multiple <span class="hlt">shock</span> <span class="hlt">compression</span> may further desensitize these materials. Although the desensitization criterion for HMX based plastic bonded explosive PBX9404 has long been determined, no such criterion for TATB based explosives has yet been determined. In the present paper the desensitization criterion for TATB based explosive is proposed, based on recently performed experiments. By using a model which employs the proposed criterion to account for the desensitization effects in TATB based explosives, numerical simulations of the multiple <span class="hlt">shock</span> experiments have been performed. The calculated results agree closely with the experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ShWav..16..455A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ShWav..16..455A"><span id="translatedtitle">Moving <span class="hlt">shocks</span> through metallic grids: their interaction and potential for blast <span class="hlt">wave</span> mitigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andreopoulos, Y.; Xanthos, S.; Subramaniam, K.</p> <p>2007-07-01</p> <p>Numerical simulations and laboratory measurements have been used to illuminate the interaction of a moving <span class="hlt">shock</span> <span class="hlt">wave</span> impacting on metallic grids at various <span class="hlt">shock</span> strengths and grid solidities. The experimental work was carried out in a large scale <span class="hlt">shock</span> tube facility while computational work simulated the flow field with a time-dependent inviscid and a time-dependent viscous model. The pressure drop measured across the grids is a result of two phenomena which are associated with the impact of the <span class="hlt">shock</span> on the metallic grids. First are the reflection and refraction of the incoming <span class="hlt">shock</span> on the grid itself. This appears to be the main inviscid mechanism associated with the reduction of the strength of the transmitted <span class="hlt">shock</span>. Second, viscous phenomena are present during the reflection and refraction of the <span class="hlt">wave</span> as well as during the passage of the induced flow of the air through the grid. The experimental data of pressure drop across the grid obtained in the present investigation are compared with those obtained from computations. The numerical results slightly overpredict the experimental data of relative pressure drop which increases substantially with grid solidity at fixed flow Mach numbers. The processes of <span class="hlt">shock</span> reflection and refraction are continuous and they can be extended in duration by using thicker grids that will result in lower <span class="hlt">compression</span> rates of the structural loading and increase the viscous losses associated with these phenomena which will further attenuate the impacting <span class="hlt">shock</span>. Preliminary theoretical analysis suggests that the use of a graded porosity/solidity material will result in higher pressure drop than a constant porosity/solidity material and thus provide effective blast mitigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20821262','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20821262"><span id="translatedtitle">Potential of <span class="hlt">shock</span> <span class="hlt">waves</span> to remove calculus and biofilm.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Müller, Philipp; Guggenheim, Bernhard; Attin, Thomas; Marlinghaus, Ernst; Schmidlin, Patrick R</p> <p>2011-12-01</p> <p>Effective calculus and biofilm removal is essential to treat periodontitis. Sonic and ultrasonic technologies are used in several scaler applications. This was the first feasibility study to assess the potential of a <span class="hlt">shock</span> <span class="hlt">wave</span> device to remove calculus and biofilms and to kill bacteria. Ten extracted teeth with visible subgingival calculus were treated with either <span class="hlt">shock</span> <span class="hlt">waves</span> for 1 min at an energy output of 0.4 mJ/mm(2) at 3 Hz or a magnetostrictive ultrasonic scaler at medium power setting for 1 min, which served as a control. Calculus was determined before and after treatment planimetrically using a custom-made software using a grey scale threshold. In a second experiment, multispecies biofilms were formed on saliva-preconditioned bovine enamel discs during 64.5 h. They were subsequently treated with <span class="hlt">shock</span> <span class="hlt">waves</span> or the ultrasonic scaler (N = 6/group) using identical settings. Biofilm detachment and bactericidal effects were then assessed. Limited efficiency of the <span class="hlt">shock</span> <span class="hlt">wave</span> therapy in terms of calculus removal was observed: only 5% of the calculus was removed as compared to 100% when ultrasound was used (P ≤ 0.0001). However, <span class="hlt">shock</span> <span class="hlt">waves</span> were able to significantly reduce adherent bacteria by three orders of magnitude (P ≤ 0.0001). The extent of biofilm removal by the ultrasonic device was statistically similar. Only limited bactericidal effects were observed using both methods. Within the limitations of this preliminary study, the <span class="hlt">shock</span> <span class="hlt">wave</span> device was not able to reliably remove calculus but had the potential to remove biofilms by three log steps. To increase the efficacy, technical improvements are still required. This novel noninvasive intervention, however, merits further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JEPT...89..795K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JEPT...89..795K"><span id="translatedtitle">Dynamics of a "Two-Phase" Bubble in <span class="hlt">Compression</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khabeev, N. S.</p> <p>2016-07-01</p> <p>The behavior of a vapor envelope around a heated solid particle in a variable pressure field has been studied. Problems of this kind arise in propagation of <span class="hlt">shock</span> <span class="hlt">waves</span> in three-phase systems ″liquid-hot solid particles surrounded by vapor envelopes.″ The behavior of the system in the vicinity of the forward <span class="hlt">shock</span> <span class="hlt">wave</span> front on a linear rise in pressure in the system has been studied analytically. A simple formula describing the change in the radius of the vapor layer in time has been obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMMR13B1681L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMMR13B1681L"><span id="translatedtitle">The effects of vacancy on melting of Cu under hydrostatic and <span class="hlt">shock</span> <span class="hlt">wave</span> loading</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, H.; Ni, S.</p> <p>2009-12-01</p> <p>Defects, ubiquitous in real solids, are relevant to high pressure melting under static and <span class="hlt">shock</span> loading conditions as in the Earth’s interior and during planetary impact. A simplest type of defects is vacancy, and we investigate melt- ing of a representative metal (Cu) with pre-existing vacan- cies under hydrostatic and <span class="hlt">shock</span> <span class="hlt">wave</span> loading using molec- ular dynamics simulations. The equilibrium melting curve is established with the superheating-supercooling hysteresis method. During hydrostatic <span class="hlt">compression</span>, the vacancy con- centration is reduced from its initial value and the vacancy effect on melting is minimized at high pressures. <span class="hlt">Shock</span> <span class="hlt">wave</span> loading is conducted along h100i at different initial vacancy concentrations. Considerable superheating occurs for initial vacancy concentration<2%. Quasi-continuous and continu- ous melting are found for vacancy concentration>5%. Dur- ing <span class="hlt">shock</span> loading, preexistent vacancies facilitate plasticity and other defect formation, and thus reduce melting temper- ature. Our results indicate that vacancy effect on melting should be considered for <span class="hlt">shock</span> loading and for low hydro- static pressures. 1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990008041&hterms=Uranus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DUranus','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990008041&hterms=Uranus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DUranus"><span id="translatedtitle">A Study of Uranus' Bow <span class="hlt">Shock</span> Motions Using Langmuir <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Xue, S.; Cairns, I. H.; Smith, C. W.; Gurnett, D. A.</p> <p>1996-01-01</p> <p>During the Voyager 2 flyby of Uranus, strong electron plasma oscillations (Langmuir <span class="hlt">waves</span>) were detected by the plasma <span class="hlt">wave</span> instrument in the 1.78-kHz channel on January 23-24, 1986, prior to the inbound bow <span class="hlt">shock</span> crossing. Langmuir <span class="hlt">waves</span> are excited by energetic electrons streaming away from the bow <span class="hlt">shock</span>. The goal of this work is to estimate the location and motion of Uranus' bow <span class="hlt">shock</span> using Langmuir <span class="hlt">wave</span> data, together with the spacecraft positions and the measured interplanetary magnetic field. The following three remote sensing analyses were performed: the basic remote sensing method, the lag time method, and the trace-back method. Because the interplanetary magnetic field was highly variable, the first analysis encountered difficulties in obtaining a realistic estimation of Uranus' bow <span class="hlt">shock</span> motion. In the lag time method developed here, time lags due to the solar wind's finite convection speed are taken into account when calculating the <span class="hlt">shock</span>'s standoff distance. In the new trace-back method, limits on the standoff distance are obtained as a function of time by reconstructing electron paths. Most of the results produced by the latter two analyses are consistent with predictions based on the standard theoretical model and the measured solar wind plasma parameters. Differences between our calculations and the theoretical model are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950046290&hterms=whistler&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwhistler','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950046290&hterms=whistler&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwhistler"><span id="translatedtitle">An analysis of whistler <span class="hlt">waves</span> at interplanetary <span class="hlt">shocks</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lengyel-Frey, D.; Farrell, W. M.; Stone, R. G.; Balogh, A.; Forsyth, R.</p> <p>1994-01-01</p> <p>We present an analysis of whistler <span class="hlt">wave</span> magnetic and electric field amplitude ratios from which we compute <span class="hlt">wave</span> propagation angles and energies of electrons in resonance with the <span class="hlt">waves</span>. To do this analysis, we compute the theoretical dependence of ratios of <span class="hlt">wave</span> components on the whistler <span class="hlt">wave</span> propagation angle Theta for various combinations of orthogonal <span class="hlt">wave</span> components. Ratios of <span class="hlt">wave</span> components that would be observed by a spinning spacecraft are determined, and the effects of arbitrary inclinations of the spacecraft to the ambient magnetic field and to the whistler <span class="hlt">wave</span> vector are studied. This analysis clearly demonstrates that B/E, the ratio of magnetic to electric field amplitudes, cannot be assumed to be the <span class="hlt">wave</span> index of refraction, contrary to assumptions of some earlier studies. Therefore previous interpretations of whistler <span class="hlt">wave</span> observations based on this assumption must be reinvestigated. B/E ratios derived using three orthogonal <span class="hlt">wave</span> components can be used to unambiguously determine Theta. Using spin plane observations alone, a significant uncertainty occurs in the determination of Theta. Nevertheless, for whistler <span class="hlt">waves</span> observed downstream of several interplanetary <span class="hlt">shocks</span> by the Ulysses plasma <span class="hlt">wave</span> experiment we find that Theta is highly oblique. We suggest that the analysis of <span class="hlt">wave</span> amplitude ratios used in conjunction with traditional stability analyses provide a promising tool for determining which particle distributions and resonances are likely to be dominant contributors to <span class="hlt">wave</span> growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20854065','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20854065"><span id="translatedtitle">Inertial-Fusion-Related Hydrodynamic Instabilities in a Spherical Gas Bubble Accelerated by a Planar <span class="hlt">Shock</span> <span class="hlt">Wave</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Niederhaus, John; Ranjan, Devesh; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo; Greenough, Jeff</p> <p>2005-05-15</p> <p>Experiments studying the <span class="hlt">compression</span> and unstable growth of a dense spherical bubble in a gaseous medium subjected to a strong planar <span class="hlt">shock</span> <span class="hlt">wave</span> (2.8 < M < 3.4) are performed in a vertical <span class="hlt">shock</span> tube. The test gas is initially contained in a free-falling spherical soap-film bubble, and the <span class="hlt">shocked</span> bubble is imaged using planar laser diagnostics. Concurrently, simulations are carried out using a <span class="hlt">compressible</span> hydrodynamics code in r-z axisymmetric geometry.Experiments and computations indicate the formation of characteristic vortical structures in the post-<span class="hlt">shock</span> flow, due to Richtmyer-Meshkov and Kelvin-Helmholtz instabilities, and smaller-scale vortices due to secondary effects. Inconsistencies between experimental and computational results are examined, and the usefulness of the current axisymmetric approach is evaluated.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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