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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. Compression of High Porosity Aluminum by Strong Shock Waves

    SciTech Connect

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

    2006-08-03

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

  3. Shock wave compression of iron-silicate garnet.

    NASA Technical Reports Server (NTRS)

    Graham, E. K.; Ahrens, T. J.

    1973-01-01

    Shock wave compression data to over 650 kb are presented for single-crystal almandine garnet. The data indicate the initiation of a phase transformation near 200 kb. Total transition to the high-pressure polymorph occurs at approximately 300 kb. The elastic properties of the high-pressure phase are calculated from the metastable Hugoniot data by using the linear shock velocity-particle velocity relationships. The overall results obtained strongly suggest that upper mantle minerals are likely to occur in the ilmenite structure over a substantial part of the lower mantle.

  4. A study on compressive shock wave propagation in metallic foams

    NASA Astrophysics Data System (ADS)

    Wang, Zhihua; Zhang, Yifen; Ren, Huilan; Zhao, Longmao

    2010-02-01

    Metallic foam can dissipate a large amount of energy due to its relatively long stress plateau, which makes it widely applicable in the design of structural crashworthiness. However, in some experimental studies, stress enhancement has been observed when the specimens are subjected to intense impact loads, leading to severe damage to the objects being protected. This paper studies this phenomenon on a 2D mass-spring-bar model. With the model, a constitutive relationship of metal foam and corresponding loading and unloading criteria are presented; a nonlinear kinematics equilibrium equation is derived, where an explicit integration algorithm is used to calculate the characteristic of the compressive shock wave propagation within the metallic foam; the effect of heterogeneous distribution of foam microstructures on the shock wave features is also included. The results reveal that under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, which then reduces the crush of objects. When the pulse is sufficiently high, on the other hand, stress enhancement may take place, especially in the heterogeneous foams, where high peak stresses usually occur. The characteristics of compressive shock wave propagation in the foam and the magnitude and location of the peak stress produced are strongly dependent on the mechanical properties of the foam material, amplitude and period of the pulse, as well as the homogeneity of the microstructures. This research provides valuable insight into the reliability of the metallic foams used as a protective structure.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. 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.

  8. 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.

  9. Control of shock wave-boundary layer interactions by bleed in supersonic mixed compression inlets

    NASA Technical Reports Server (NTRS)

    Fukuda, M. K.; Hingst, W. G.; Reshotko, E.

    1975-01-01

    An experimental investigation was conducted to determine the effect of bleed on a shock wave-boundary layer interaction in an axisymmetric mixed-compression supersonic inlet. The inlet was designed for a free-stream Mach number of 2.50 with 60-percent supersonic internal area contraction. The experiment was conducted in the NASA Lewis Research Center 10-Foot Supersonic Wind Tunnel. The effects of bleed amount and bleed geometry on the boundary layer after a shock wave-boundary layer interaction were studied. The effect of bleed on the transformed form factor is such that the full realizable reduction is obtained by bleeding of a mass flow equal to about one-half of the incident boundary layer mass flow. More bleeding does not yield further reduction. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise.

  10. 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.

  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

    2016-03-01

    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. 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.

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

    SciTech Connect

    Roy S. Baty, F. Farassat, John A. Hargreaves

    2007-05-25

    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. 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.

  15. Response of Pt-based Bulk Metallic Glass to Shock Wave Compression

    NASA Astrophysics Data System (ADS)

    Lalone, B. M.; Gupta, Y. M.

    2009-06-01

    Plate impact experiments were performed on platinum based bulk metallic glass (BMG) samples having a nominal composition of Pt57.5Cu14.7Ni5.3P22.5, a material previously reported to support large plastic strains under quasi-static, uniaxial stress loading (J. Schroers, and W. L. Johnson, Phys. Rev. Lett. 93, 255506 (2004)). In the present shock wave experiments, peak longitudinal stresses ranged from 9-30 GPa. Piezoelectric pins and a velocity interferometer were used to measure shock velocities and particle velocity histories. A clear two-wave structure was observed in the particle velocity histories indicating an elastic-plastic response. The elastic wave amplitude was dependent on peak stress and sample thickness, with values ranging from 8.6 - 14.2 GPa. Measured wave profiles were converted to stress-density compression, and a nonlinear elastic model was fit to the measured elastic response. Unlike the quasi-static, uniaxial stress data on the same alloy, the shock wave, uniaxial strain results show a loss of strength above the elastic limit. Reasons for this strength loss are discussed. Work supported by the DOE.

  16. Shock-wave compression and release of aluminum/ceramic composites

    SciTech Connect

    Johnson, J.N.; Hixson, R.S.; Gray, G.T. III )

    1994-11-15

    Several composite materials consisting of ceramic particles embedded in a 6061-T6 aluminum matrix have been studied under conditions of shock-wave compression and release, including spallation. The 6061-T6 matrix represents a material for which high-rate shock-wave response has been extremely well characterized for thermoelastic-plastic deformation. The ceramic particles (alumina and mullite) are also well characterized, particularly in the elastic regime. Experimental tests consist of quasistatic, uniaxial-stress compression of both virgin and shock-recovered samples as well as time-resolved velocity interferometer measurements under conditions of flat-plate impact. The latter tests were performed with lithium fluoride windows for transmitted wave studies and free surfaces for spallation measurement. Theoretical analysis of the data is carried out with a pseudodissipation model originated by Barker [J. Composite Mat. [bold 5], 140 (1971)] for application to elastic deformation of layered composites and generalized here to include thermoelastic-plastic properties of the constituents. For a pseudodissipative model to apply to composite material response, significant geometrical randomization must be present in the composite structure; this is something that all commercially produced composites naturally possess. Randomization produces mechanical energy traps, which convert some fraction of regular, directed motion into random elastic vibrations behind the shock front. Within a few microseconds (depending on the pinned dislocation segment density) this macroscale, continuum vibrational energy is converted to heat by means of the anelastic properties of the metal matrix. The use of pseudodissipation as a means of representing dispersive composite material behavior is thus placed on a more secure physical foundation.

  17. 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.

  18. 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

  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. Shock wave compression and release of hexagonal-close-packed metal single crystals: Inelastic deformation of c-axis magnesium

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    To understand inelastic deformation mechanisms for shocked hexagonal-close-packed (hcp) metals, shock compression and release wave profiles, previously unavailable for hcp single crystals, were measured for c-axis magnesium crystals. The results show that the elastic-inelastic loading response is strongly time-dependent. Measured release wave profiles showed distinct peaked features, which are unusual for inelastic deformation during unloading of shocked metals. Numerical simulations show that pyramidal slip provides a reasonably good description of the inelastic loading response. However, { 10 1 ¯ 2 } twinning is needed to explain the unloading response. The results and analysis presented here provide insight into the relative roles of dislocation slip and deformation twinning in the response of shocked hcp metals.

  1. Breakdown and critical field evaluation for porous PZT 95/5 ferroelectric ceramics under shock wave compression

    NASA Astrophysics Data System (ADS)

    Jiang, Yixuan; Wang, Xingzhe; Zhang, Fuping; He, Hongliang

    2014-08-01

    Bounded charges of PZT 95/5 ferroelectric ceramics with polarization can be rapidly released by shock wave loadings to form a high-power electrical energy output, which motivates pulsed power applications of ferroelectric materials. In the present paper, we first investigated experimentally the depoling current and output electric field, as well as the critical electric fields of breakdown for porous PZT 95/5 ceramics in the normal shock-wave-loaded mode by means of a gas-gun facility. By combining the output electric-field profile by shock loading with the breakdown of the quasi-static electric field, we were able to theoretically evaluate the range of the breakdown field for porous ferroelectric ceramics with different porosities under shock wave compression. Although it is a rough bound-field evaluation on breakdown of shocked porous PZT 95/5 ferroelectric ceramics suggested in the present work, it sounds reasonable and the predictions of critical field-bounds on the breakdown show good agreement with the magnitude of the experimental results. The influences of load resistance, porosity and velocity of shock wave on the lower and upper bounds of critical electric field for poled porous PZT 95/5 ceramics during the discharge process were also discussed.

  2. 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.

  3. Excitation of dayside chorus waves due to magnetic field line compression in response to interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Li, Wen; Thorne, Richard M.; Bortnik, Jacob; Ma, Qianli; An, Xin; Zhang, Xiao-jia; Angelopoulos, Vassilis; Ni, Binbin; Gu, Xudong; Fu, Song; Zhao, Zhengyu

    2015-10-01

    The excitation of magnetospheric whistler-mode chorus in response to interplanetary (IP) shocks is investigated using wave data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. As an example, we show a typical chorus wave excitation following an IP shock event that was observed by THEMIS in the postnoon sector near the magnetopause on 3 August 2010. We then analyze characteristic changes during this event and perform a survey of similar events during the period 2008-2014 using the THEMIS and OMNI data set. Our statistical analysis demonstrates that the chorus wave excitation/intensification in response to IP shocks occurs only at high L shells (L > 8) on the dayside. We analyzed the variations of magnetic curvature following the arrival of the IP shock and found that IP shocks lead to more homogeneous background magnetic field configurations in the near-equatorial dayside magnetosphere; and therefore, the threshold of nonlinear chorus wave growth is likely to be reduced, favoring chorus wave generation. Our results provide the observational evidence to support the concept that the geomagnetic field line configuration plays a key role in the excitation of dayside chorus.

  4. 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

  5. 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

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

    DOE PAGESBeta

    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

  7. 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

  8. Shock compression of liquid hydrazine

    SciTech Connect

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

    1996-05-01

    Liquid hydrazine (N{sub 2}H{sub 4}) is a propellant used for aerospace propulsion and power systems. Because the propellant modules 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 to investigate the shock detonability of liquid hydrazine; however, the experiments{close_quote} 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. {copyright} {ital 1996 American Institute of Physics.}

  9. 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.

  10. 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.

  11. 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.

  12. Compression Shocks of Detached Flow

    NASA Technical Reports Server (NTRS)

    Eggink

    1947-01-01

    It is known that compression shocks which lead from supersonic to subsonic velocity cause the flow to separate on impact on a rigid wall. Such shocks appear at bodies with circular symmetry or wing profiles on locally exceeding sonic velocity, and in Laval nozzles with too high a back pressure. The form of the compression shocks observed therein is investigated.

  13. 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.

  14. Shock compression of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Neogi, Anupam; Mitra, Nilanjan

    2016-04-01

    This study presents shock compression simulation of atactic polyvinyl chloride (PVC) using ab-initio and classical molecular dynamics. The manuscript also identifies the limits of applicability of classical molecular dynamics based shock compression simulation for PVC. The mechanism of bond dissociation under shock loading and its progression is demonstrated in this manuscript using the density functional theory based molecular dynamics simulations. The rate of dissociation of different bonds at different shock velocities is also presented in this manuscript.

  15. Interstellar shock waves

    NASA Technical Reports Server (NTRS)

    Mckee, C. F.; Hollenbach, D. J.

    1980-01-01

    The structure of interstellar shocks driven by supernova remnants and by expanding H II regions around early-type stars is discussed. Jump conditions are examined, along with shock fronts, post-shock relaxation layers, collisional shocks, collisionless shocks, nonradiative shocks, radiative atomic shocks, and shock models of observed nebulae. Effects of shock waves on interstellar molecules are examined, with reference to the chemistry behind shock fronts, infrared and vibrational-rotational cooling by molecules, and observations of shocked molecules. Some current problems and applications of the study of interstellar shocks are summarized, including the initiation of star formation by radiative shock waves, interstellar masers, the stability of shocks, particle acceleration in shocks, and shocks in galactic nuclei.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. Dissipative processes under the shock compression of glass

    NASA Astrophysics Data System (ADS)

    Savinykh, A. S.; Kanel, G. I.; Cherepanov, I. A.; Razorenov, S. V.

    2016-03-01

    New experimental data on the behavior of the K8 and TF1 glasses under shock-wave loading conditions are obtained. It is found that the propagation of shock waves is close to the self-similar one in the maximum compression stress range 4-12 GPa. Deviations from a general deformation diagram, which are related to viscous dissipation, take place when the final state of compression is approached. The parameter region in which failure waves form in glass is found not to be limited to the elastic compression stress range, as was thought earlier. The failure front velocity increases with the shock compression stress. Outside the region covered by a failure wave, the glasses demonstrate a high tensile dynamic strength (6-7 GPa) in the case of elastic compression, and this strength is still very high after transition through the elastic limit in a compression wave.

  4. 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

  5. Rayleigh-Taylor Shock Waves

    SciTech Connect

    Olson, B J; Cook, A W

    2007-08-30

    Beginning from a state of hydrostatic equilibrium, in which a heavy gas rests atop a light gas in a constant gravitational field, Rayleigh-Taylor instability at the interface will launch a shock wave into the upper fluid. The rising bubbles of lighter fluid act like pistons, compressing the heavier fluid ahead of the fronts and generating shocklets. These shocklets coalesce in multidimensional fashion into a strong normal shock, which increases in strength as it propagates upwards. Large-eddy simulations demonstrate that the shock Mach number increases faster in three dimensions than it does in two dimensions. The generation of shocks via Rayleigh-Taylor instability could have profound implications for astrophysical flows.

  6. 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.

  7. When shock waves collide

    DOE PAGESBeta

    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

  8. 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.

  9. Effect of high-temperature shock-wave compression on few-layer MoS2, WS2 and MoSe2

    NASA Astrophysics Data System (ADS)

    Vasu, K.; Matte, H. S. S. R.; Shirodkar, Sharmila N.; Jayaram, V.; Reddy, K. P. J.; Waghmare, Umesh V.; Rao, C. N. R.

    2013-09-01

    Exposure of few-layer MoS2, WS2 and MoSe2 to high-temperature shock waves causes morphological changes and a significant decrease in the interlayer separation between the (0 0 2) planes, the decrease being greatest in MoSe2. Raman spectra show softening of both the A1g and the E2g1 modes initially, followed by a slightly stiffening. Using first-principles density functional theoretical analysis of the response of few-layer MoS2 to shock waves, we propose that a combination of shear and uniaxial compressive deformation leads to flattening of MoS2 sheets which is responsible for the changes in the vibrational spectra.

  10. 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.

  11. New Developments in the Physical Chemistry of Shock Compression

    NASA Astrophysics Data System (ADS)

    Dlott, Dana D.

    2011-05-01

    This review discusses new developments in shock compression science with a focus on molecular media. Some basic features of shock and detonation waves, nonlinear excitations that can produce extreme states of high temperature and high pressure, are described. Methods of generating and detecting shock waves are reviewed, especially those using tabletop lasers that can be interfaced with advanced molecular diagnostics. Newer compression methods such as shockless compression and precompression shock that generate states of cold dense molecular matter are discussed. Shock compression creates a metallic form of hydrogen, melts diamond, and makes water a superionic liquid with unique catalytic properties. Our understanding of detonations at the molecular level has improved a great deal as a result of advanced nonequilibrium molecular simulations. Experimental measurements of detailed molecular behavior behind a detonation front might be available soon using femtosecond lasers to produce nanoscale simulated detonation fronts.

  12. 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.

  13. 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.

  14. Shock Compression of Liquid Hydrazine.

    NASA Astrophysics Data System (ADS)

    Voskoboinikov, I. M.

    1999-06-01

    The possibility of calculation of the parameters of a shock compression of liquid hydrazine within the frameworks of the schemes is shown. When the mass velocities behind shock fronts do not exceed the value equals 3.1 km/s, it may be managed under assumption of the retention of the initial compound (hydrazine) behind a shock front. The detonation velocities of hydrazine solutions with nitromethane and hydrazinenitrate correspond to the destruction of hydrazine up to ammonia and nitrogen that is accompanied by a noticeable energy release. The estimates performed demonstrate a possibility of the detonation of a liquid hydrazine with the velocity equals 8 km/s, during which the heating up of the substance behind a shock front (equals approximately 2000 K) is comparable with those observed during detonation of liquid explosives. The large values of the critical diameter of detonation are expected because of activation energy of hydrazine decomposition equals 53.2 kcal/mol. They are decreased up on addition of a certain amount of liquid explosives. Their more rapid decomposition behind a shock front gives rise to the temperature increase that is sufficient for destruction of hydrazine.

  15. 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.

  16. Isentropic expansion of shock-compressed substances.

    NASA Astrophysics Data System (ADS)

    Zhernokletov, M. V.

    2001-06-01

    The below parts of the paper are devoted to experimental results = obtained by the barrier method when researching metals, explosion = products, and polymers. Metals. The method of isentropic expansion was used to research = trancritical states of copper, lead, bismuth, molybdenum, uranium, = tungsten, nickel, tin, chrome, and zinc. To increase entropy under shock = compression and realize trancritical states during expansion, porous = samples were used. The highest degrees of expansion are reached on = isentropes obtained with use of hemispherical generators of shock waves. = The performed tests showed absence of significant jumps of thermodynamic = function or any hydrodynamic anomalies which could be interpeted as = specific plasma phase transformations. The tests data testify to = continuous change of metals properties at expansion from the condensed = state up to the gas state. Isentropes of explosion products (EP). In tests the shock wave = parameters were determined in inert materials-obstacles directly = contacting HE under research. TNT and two TNT-RDX alloys (50/50 and = 25/75) were used as this HE. The experimental data were compared with = data obtained by calculations using various EOS, including the cubic EOS = (P=3DAρ^3). It is shown that the cubic EOS has significant = disagreement with test in the area below 1 GPa. Polymeric materials. Teflon, polystyrene, plexiglas, phenylone, and = stilbene are studied. Analysis of experimental data testifies that = polystyrene, phenylone, and stilbene undergo a series of = physical-chemical transformations with pressure growth in the front of = shock-waves.

  17. Unsteady interaction of shock and detonation waves in gases

    NASA Astrophysics Data System (ADS)

    Korobeinikov, Viktor P.

    Recent theoretical and experimental investigations of unsteady shock-wave interactions (SWIs) in gases are discussed in chapters contributed by leading Soviet experts. Topics addressed include the thermodynamic and electrophysical parameters of gas flow behind shock waves, the effect of nonequilibrium physicochemical processes on the flow parameters behind a shock wave, shock-tube investigations of unsteady SWI, SWI with a porous compressible medium, and the reflection of shock waves by a plane surface. Consideration is given to the diffraction of a shock wave at a convex corner, unsteady SWIs with curvilinear surfaces, numerical simulations of SWIs with bodies of various shapes, and the unsteady interaction of detonation waves. Diagrams, graphs, and photographs.

  18. 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.

  19. The behavior of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient. Ph.D. Thesis - Washington Univ., Seattle, Aug. 1972

    NASA Technical Reports Server (NTRS)

    Rose, W. C.

    1973-01-01

    The results of an experimental investigation of the mean- and fluctuating-flow properties of a compressible turbulent boundary layer in a shock-wave-induced adverse pressure gradient are presented. The turbulent boundary layer developed on the wall of an axially symmetric nozzle and test section whose nominal free-stream Mach number and boundary-layer thickness Reynolds number were 4 and 100,000, respectively. The adverse pressure gradient was induced by an externally generated conical shock wave. Mean and time-averaged fluctuating-flow data, including the complete experimental Reynolds stress tensor and experimental turbulent mass- and heat-transfer rates are presented for the boundary layer and external flow, upstream, within and downstream of the pressure gradient. The mean-flow data include distributions of total temperature throughout the region of interest. The turbulent mixing properties of the flow were determined experimentally with a hot-wire anemometer. The calibration of the wires and the interpretation of the data are discussed. From the results of the investigation, it is concluded that the shock-wave - boundary-layer interaction significantly alters the turbulent mixing characteristics of the boundary layer.

  20. Visualization of shock-wave formation processes during shock reflection at obstacles with multiple steps

    NASA Astrophysics Data System (ADS)

    Kobayashi, Susumu; Adachi, Takashi

    According to standard textbooks on compressible fluid dynamics, a shock wave is formed by an accumulation of compression waves. However, the process by which an accumulated compression wave grows into a shock wave has never been visualized. In the present paper, the authors tried to visualize this process using a model wedge with multiple steps. This model is useful for generating a series of compression waves and can simulate a compression process that occurs in a shock tube. By estimating the triple-point trajectory angle, we demonstrated visually that an accumulated compression wave grows into a shock wave. Further reflection experiments over a rough-surface wedge confirmed the tendency for the triple point trajectory angle χ to reach the asymptotic value χs in the end.

  1. 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.

  2. 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

  3. Turbulence measurements in a compressible boundary layer subjected to a shock-wave-induced adverse pressure gradient.

    NASA Technical Reports Server (NTRS)

    Rose, W. C.

    1973-01-01

    The rms intensities of fluctuating mass flux and total temperature and their correlation coefficients are given for the case of an adiabatic, Mach 4, axisymmetric shock-wave boundary-layer interaction. Data were obtained upstream, within, and downstream of the interaction by the use of constant temperature hot-wire anemometer. Turbulence spectra and quantitative behavior from oscilloscope traces are shown at selected locations. The measurements indicate that certain frequencies of the turbulence are increased as a result of the interaction and that the mass flux and total temperature fluctuations remain highly correlated over most of the boundary layer throughout the interaction. The present data are also transformed to rms intensities of fluctuating static temperature and velocity and compared with existing data obtained in adiabatic flows.

  4. 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.

  5. Shock Compression of Ammonium Perchlorate Single Crystals

    NASA Astrophysics Data System (ADS)

    Gupta, Y. M.; Yuan, Gang; Feng, Ruqiang

    1997-07-01

    The shock response of ammonium perchlorate (AP) single crystals has been examined for uniaxial strain compression along the [210] and [001] directions. Quartz gauge and VISAR measurements have provided the wave profiles at the impact surface and after propagation through thin samples (1-3 mm thickness) for peak stresses ranging between 10 and 65 kbar. A two wave structure due to elastic-plastic deformation was observed for both orientations. The measured HEL values for the [210] and [001] orientations were about 4.3 and 3.5 kbar, respectively. Data for the two orientations reveal small stress relaxation effects and small differences due to crystal orientation effects. We have chosen to fit both sets of results with a simple elastic-perfectly plastic model used for isotropic materials. Reasonable agreement between the calculations and experimental results was obtained. Over the stress range examined to date, no evidence of chemical decomposition was observed for the time durations in our experiments.

  6. 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}shock wave solutions to the Maxwell-Cattaneo equations cannot be found, and PMID:27078450

  7. Fast Electron Deposition in Laser Shock Compressed Plastic Targets

    NASA Astrophysics Data System (ADS)

    Hall, T. A.; Ellwi, S.; Batani, D.; Bernardinello, A.; Masella, V.; Koenig, M.; Benuzzi, A.; Krishnan, J.; Pisani, F.; Djaoui, A.; Norreys, P.; Neely, D.; Rose, S.; Key, M. H.; Fews, P.

    1998-08-01

    We present the first results of fast electron deposition in a laser shock compressed plasma. The interaction of a 3 ps, 15 J laser pulse with solid polyethylene targets is used to produce fast electrons on one side of foil targets and a 2 ns duration laser pulse is used to drive a shock wave into the target from the opposite side. Kα emission from chlorine fluor buried layers is used to measure the electron transport. The hot electron range in the shock compressed plastic is found to be approximately twice as large as the range in the solid density plastic.

  8. NONEQUILIBRIUM FLUCTUATIONS IN SHOCK COMPRESSION OF POLYCRYSTALLINE ALPHA-IRON

    SciTech Connect

    Y. HORIE; K. YANO

    2001-06-01

    We report a numerical study of heterogeneous and nonequilibrium fluctuations in shock compression of {alpha}-iron at the grain level. A quasi-molecular code called DM2 is used to model the interactions of a plane shock wave with grain boundaries and crystal anisotropy over the pressure range of 5-45 GPa. Highly transient eddies that were reported earlier are again observed. We show new features through an elementary statistical analysis. They are (1) a characteristic decay constant for the non-equilibrium fluctuation on the order of 20ns, (2) a resonance phenomenon at an intermediate shock pressure, and (3) a more uniform shock structure for very high pressures.

  9. 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.

  10. Shock-wave surfing

    SciTech Connect

    Laurence, Stuart J; Deiterding, Ralf

    2011-01-01

    A phenomenon referred to as shock-wave surfing , in which a body moves in such a way as to follow the shock wave generated by another upstream body, is investigated numerically and theoretically. This process can lead to the downstream body accumulating a significantly higher lateral velocity than would otherwise be possible, and thus is of importance in situations such as meteoroid fragmentation, in which the fragment separation behaviour following disruption is determined to a large extent by aerodynamic effects. The surfing effect is first investigated in the context of interactions between a sphere and a planar oblique shock. Numerical simulations are performed and a simple theoretical model is developed to determine the forces acting on the sphere. A phase-plane description is employed to elucidate features of the system dynamics. The theoretical model is then generalised to the more complex situation of aerodynamic interactions between two spheres, and, through comparisons with further computations, is shown to adequately predict, in particular, the final separation velocity of the surfing sphere in initially touching configurations. Both numerical simulations and theory indicate a strong influence of the body radius ratio on the separation process and predict a critical radius ratio for initially touching fragments that delineates entrainment of the smaller fragment within the larger fragment s shock from expulsion; this critical ratio also results in the most extended surfing. Further, these results show that an earlier prediction for the separation velocity to scale with the square root of the radius ratio does not accurately describe the separation behaviour. The theoretical model is then employed to investigate initial configurations with varying relative sphere positions and initial velocities. A phase-space description is also shown to be useful in elucidating the dynamics of the sphere-sphere system. With regard to meteoroid fragmentation, it is shown

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Ray Tracing to Predict Optical Behaviour of Shock Compressed Dielectrics

    NASA Astrophysics Data System (ADS)

    Tear, Gareth R.; Proud, William G.

    2015-06-01

    In order to investigate the optical response of dielectric materials under shock compression, a characteristics model has been combined with a three dimensional optical ray tracing model. A general biaxial optical model is used along with a first order photoelastic model which couples the characteristics component to the optical component. This optical model is three dimensional and as such can be used to investigate small deviations from the perfect one dimensional shock wave which is typically assumed in plate impact experiments. A detailed description of the model will be presented, and comparison to available literature as well as recent experiments on the optical behaviour of shock compressed a-cut calcite and a-cut sapphire. The authors would like to thank Dr D E Eakins and Dr D J Chapman for fruitful discussions. The Institute of Shock Physics acknowledges the continued support of AWE and Imperial College London.

  16. 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.

  17. 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.

  18. Modification of the edge wave in shock wave lithotripsy

    NASA Astrophysics Data System (ADS)

    Zhou, Yufeng

    2012-10-01

    To reduce the bubble cavitation and the consequent vascular injury of shock wave lithotripsy (SWL), a new method was devised to modify the diffraction wave generated at the aperture of a Dornier HM-3 lithotripter. Subsequently, the duration of the tensile wave was shortened significantly (3.2±0.54 μs vs. 5.83±0.56 μs). However, the amplitude and duration of the compressive wave of LSW between these two groups as well as the -6 dB beam width and the amplitude of the tensile wave are almost unchanged. The suppression on bubble cavitation was confirmed using the passive cavitation technique. At the lithotripter focus, while 30 shocks can cause rupture of blood vessel phantom using the HM-3 lithotripter at 20 kV; no rupture could be found after 300 shocks with the edge extender. On the other hand, after 200 shocks the HM-3 lithotripter at 20 kV can achieve a stone fragmentation of 50.4±2.0% on plaster-of-Paris stone phantom, which is comparable to that of using the edge extender (46.8±4.1%, p=0.005). Altogether, the modification on the diffraction wave at the lithotripter aperture can significantly reduce the bubble cavitation activities. As a result, potential for vessel rupture in shock wave lithotripsy is expected.

  19. Shock compression and release in high-strength ceramics

    SciTech Connect

    Kipp, M E; Grady, D E

    1989-08-01

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

  20. Shock compression response of Ti+B reactive powder mixtures

    NASA Astrophysics Data System (ADS)

    Gonzales, M.; Gurumurthy, A.; Kennedy, G. B.; Gokhale, A. M.; Thadhani, N. N.

    2014-05-01

    The shock compression response of Ti+2B (1:2 Ti:B stoichiometric ratio) reactive powder mixtures at ~50% theoretical material density (TMD) is investigated for shock pressures up to 5 GPa to investigate the possible shock-induced chemical reactivity of this highly exothermic mixture. The shock adiabat is produced from instrumented parallel-plate gas-gun impact experiments on encapsulated powders using poly-vinylidene fluoride (PVDF) stress gauges to measure the input and propagated stresses and wave speed in the powder. The shock compression regime is probed from crush-up to full density and onward to assess the potential onset of a shock-induced chemical reaction event in the powder mixture. A series of two-dimensional continuum meso-scale simulations on validated simulated microstructures are performed to predict the shock compression response and identify the meso-scale mechanics that are essential for reaction. The suitability of the synthetic microstructural representations is evaluated by comparing the experimental and predicted pressure traces.

  1. Shock compression response of Ti+B reactive powder mixtures

    NASA Astrophysics Data System (ADS)

    Gonzales, Manny; Gurumurthy, Ashok; Kennedy, Gregory; Gokhale, Arun; Thadhani, Naresh

    2013-06-01

    The shock compression response of Ti+2B (1:2 Ti:B stoichiometric ratio) reactive powder mixtures at ~50% theoretical material density (TMD) is investigated for shock pressures up to 5 GPa to investigate the possible shock-induced chemical reactivity of this highly exothermic mixture. The shock adiabat is produced from instrumented parallel-plate gas-gun impact experiments on encapsulated powders using poly-vinylidene fluoride (PVDF) stress gauges to measure the input and propagated stress and wave speed in the powder. The shock compression regime is probed from crush-up to full density and onward to assess the potential onset of a shock-induced chemical reaction event in the powder mixture. A series of two-dimensional continuum meso-scale simulations on real and simulated microstructures are performed to predict the shock compression response and identify the meso-scale mechanics that is essential for the so-called ``ballotechnic'' reaction. These meso-scale mechanics are investigated through stereological evolution metrics that track particle interface evolution and their respective field variables. The suitability of the synthetic microstructural representations is evaluated by comparing the experimental and predicted pressure traces. We gratefully acknowledge support and funding from DTRA through Grant No. HDTRA1-10-1-0038 and the National Defense Science and Engineering Graduate (NDSEG) Fellowship through the High Performance Computing and Modernization Office (HPCMO).

  2. Shock waves: The Maxwell-Cattaneo case

    NASA Astrophysics Data System (ADS)

    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 ≈M1shock wave solutions to the Maxwell-Cattaneo equations cannot be found, and (c) for greater Mach numbers (M >M2) shock wave solutions can be found though they differ significantly from experiments.

  3. 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.

  4. Density Shock Waves in Confined Microswimmers.

    PubMed

    Tsang, Alan Cheng Hou; Kanso, Eva

    2016-01-29

    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. PMID:26871357

  5. Shock-wave properties of brittle solids

    SciTech Connect

    Grady, D.E.

    1995-10-01

    Extensive experimental investigation in the form of large-amplitude, nonlinear wave-profile measurements which manifest the shock strength and equation-of-state properties of brittle solids has been performed. Brittle materials for which a base of dynamic property data is available include Al{sub 2}O{sub 3}, AlN, B{sub 4}C, CaCO{sub 3}, SiC, Si{sub 3}N{sub 4}, SiO{sub 2} (quartz and glass), TiB{sub 2}, WC and ZrO{sub 2}. Planar impact methods and velocity interferometry diagnostics have been used exclusively to provide the high-resolution shock-profile data. These wave-profile data are providing engineering dynamic strength and equation-of-state properties as well as controlled, shock-induced motion histories for the validation of theoretical and Computational models. Of equal importance, such data are providing a window into the physics of a newly emerging understanding of the compression and deformation behavior of high-strength brittle solids. When considered along with a rich assortment of strength and deformation data in the literature, a systematic assessment of this shock-wave data lends strong support for failure waves and concomitant high-confinement dilatancy as a general mechanism of inelastic deformation in the shock compression of ceramics. Phase transformation in selected brittle solids appears to be a critical state phenomenon strongly controlled by kinetics. The risetime and structure of deformation shock waves in brittle solids are controlled by viscous effects which at present are still poorly understood. The shockwave data also suggest that both crystalline plasticity and brittle fracture may play important and interconnected roles in the dynamic failure process.

  6. 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.

  7. 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.

  8. 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.

  9. Fluorescent probes for shock compression spectroscopy

    NASA Astrophysics Data System (ADS)

    Banishev, Alexandr; Christensen, James; Dlott, Dana

    We have demonstrated the capability of using Rhodamine 6G dye as an ultrafast emission probe in high-speed shock compression of condensed matter. The ultimate time response of the probe, which functions as a high-speed pressure sensor, is limited by fundamental photophysical processes such as radiative rates, internal conversion rates and intersystem crossing rates. The time response has been greatly improved by encapsulating the dye in silica nano or microparticles. This probe was used to observed nanosecond viscoelastic shock compression of a polymer (PMMA), and has been used to monitor the response of individual grains of sand to high-speed impact.

  10. 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.

  11. Compression in radiative shocks: switch and intermediate properties

    NASA Astrophysics Data System (ADS)

    Smith, M. D.

    1993-05-01

    The degree of compression in radiative shocks (discontinuous jump followed by strong cooling) is crucial to the distribution of the phases of interstellar gas. The influence of the magnetic field, especially its direction, is studied here. In fact plane-parallel radiative shocks are switch type for a wide range of conditions. In such shocks, the magnetic field is turned through a large angle from being quasi-parallel. It is shown here that plane-parallel isothermal shocks are switch type for magnetic fields within an angle 1/A of the shock normal where A is the Alfvén number, with the stringent condition that the Alfvén speed exceeds the sound speed. The switch is usually located within the dense cooling layer rather than the shock front. Super-cooling, in which the downstream temperature drops below the pre-shock value, is often encountered. A super-cooling layer can be switch type even if the Alfvén speed is much less than the sound speed. The degree of compression is then still limited by the magnetic pressure rather than thermal pressure. Applications and predictions pertaining mainly to the interstellar medium are presented. Switch off and intermediate shocks are also studied. Supernova and super-bubble shell structures may then provide evidence for interstellar gas properties. The switch-off shock can be recognised by synchrotron radiation signatures. Also the switch-off temperature jump is shown to be closely related to the value of the ratio of Alfvén to sound speeds. Super-cooled intermediate shocks, existing when the plane-parallel assumption is relaxed, can also occur under an extended range of pre-shock states. Hence the "dimple" shell structures of some remnants do not provide evidence for high Alfvén speeds. Finally, torsional switches are presented as an alternative to intermediate waves in interpreting shell structures.

  12. 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.

  13. Some aspects of shock-wave research

    NASA Astrophysics Data System (ADS)

    Glass, I. I.

    1986-01-01

    The major portion of the paper is devoted to a specific shock-wave research problem, namely, pseudostationary oblique shock-wave reflections in perfect and imperfect gases. Consideration is given to what has been achieved to date by using two- and three-shock theory to predict what type of reflection results when a planar shock wave M(S), in a shock tube, collides with a sharp compressive wedge of angle, theta(W). Expermental (interferometric and other optical) data are presented in (M(S), theta(W))-plots for argon, nitrogen, oxygen, air, carbon-dioxide, Freon-12 and sulfurhexafluoride, in order to check the validity of the analytically predicted regions and transition lines of the four types of reflection. Some disagreements are noted and discussed. The present interferometric isopycnic data are also compared with state-of-the-art computational results from a solution of the inviscid Euler equations using a CRAY I computer. Good agreement was obtained; it would be important, however, to obtain new data by solving the Navier-Stokes equations, as well as the rate equations for imperfect-gas excitations, in order to judge the improvement obtained with real-flow interferograms.

  14. Interaction of a converging spherical shock wave with isotropic turbulence

    NASA Astrophysics Data System (ADS)

    Bhagatwala, Ankit; Lele, Sanjiva K.

    2012-08-01

    Simulations of converging spherical shock waves propagating through a region of compressible isotropic turbulence are carried out. Both converging and reflected phases of the shock are studied. Effect of the reflected phase of the shock is found to be quite different from the expanding shock in the Taylor blast wave-turbulence interaction problem. Vorticity and turbulent kinetic energy are amplified due to passage of the shock. Similar to the latter problem, the vorticity-dilatation term is primarily responsible for the observed behavior. This is confirmed through Eulerian and Lagrangian statistics. Transverse vorticity amplification is compared with linear planar shock-turbulence theory. The smallest eddies, represented by the Kolmogorov scale, decrease in size after passing through the converging shock and this is shown to be related to a decrease in kinematic viscosity and increase in dissipation behind the converging shock. Distortion of the shock due to turbulence is also investigated and quantified. Turbulence also affects maximum compression achieved at the point of shock reflection, when the shock radius is at a minimum. This decrease in compression is quantified by comparing with pure shock simulations.

  15. Quartz structure transformation under a shock wave

    NASA Astrophysics Data System (ADS)

    Vettegren', V. I.; Kuksenko, V. S.; Shcherbakov, I. P.; Mamalimov, R. I.

    2015-12-01

    The structure of a fragment formed after quartz single-crystal fracture under a shock wave has been studied using the Fourier transform infrared spectroscopy (FTIR) method. The wave is initiated by electrical breakdown of air in a hole within the single crystal. It has been found that a layer ~0.15 μm thick consisting of "diaplectic glass," i.e., quartz with a strongly distorted lattice, is formed on the fragment surface. A layer 2 μm thick with a compressed quartz lattice is located under it.

  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. Shock Wave Formation in the Collapse of a Vapor Nanobubble

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  18. Numerical calculations of shock-wave/boundary-layer flow interactions

    NASA Astrophysics Data System (ADS)

    Huang, P. G.; Liou, W. W.

    1994-08-01

    The paper presents results of calculations for 2-D supersonic turbulent compression corner flows. The results seem to indicate that the newer, improved kappa-epsilon models offer limited advantages over the standard kappa-epsilon model in predicting the shock-wave/boundary-layer flows in the 2-D compression corner over a wide range of corner angles and flow conditions.

  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. Rupture-disk-less shock-tube with compression tube driven by free piston

    NASA Astrophysics Data System (ADS)

    Abe, T.; Ogura, E.; Sato, S.; Funabiki, K.

    A new technique is proposed for a shock tube driven by a freely moving piston. In a conventional free-piston-driven shock tube, a rupture disk is employed between the compression tube and the shock generation tube. In the present method, however, the conventional rupture disk is replaced by a newly developed fast action valve which is activated by the compressed gas generated in the compression tube. The present method enables us to generate high Mach number shock waves of arbitrary strength with good reproducibility. The performance of the new method is demonstrated experimentally. This also enables us to be carefree to scattering of fragments of the rupture disk.

  1. Shock compressed solids on the Nova laser

    SciTech Connect

    Colvin, J D; Gold, D M; Kalantar, D H; Mikaelian, K O; Remington, B A; Weber, S V; Wiley, G

    1999-08-03

    Experiments are being developed to shock compress metal foils in the solid state to study the material strength under high compression. The x-ray drive has been characterized and hydrodynamics experiments performed to study growth of the Rayleigh-Taylor (RT) instability in Al foils at a peak pressure of about 1.8 Mbar. Pre-imposed modulations with an initial wavelength of lo-50 pm, and amplitude of 0.5 pm show growth. Variation in the growth factors may be a result of shot-shot variation in preheating of the Al sample due to emission from the plasma in the hohlraum target

  2. 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.

  3. Mercury's bow shock and foreshock waves observed by Messenger

    NASA Astrophysics Data System (ADS)

    Blanco-Cano, X.; Le, G.; Boardsen, S.; Chi, P.; Slavin, J. A.; Anderson, B. J.; Korth, H.

    2013-09-01

    The region upstream from a planetary bow shock is a natural plasma laboratory containing a variety of wave particle phenomena. The study of foreshocks other than the Earth's is important for extending our understanding of collisionless shocks and foreshock physics since the bow shock strength varies with heliocentric distance from the Sun, and the sizes of the bow shocks are different at different planets. Mercury's bow shock is unique in our solar system as it is produced by moderate Mach number and low plasma beta solar wind blowing over a small magnetized body with a predominately radial interplanetary magnetic field. We use Messenger high resolution (20 samples per second) magnetic field data to study Mercury's bow shock structure, and the characteristics of ultra low frequency waves observed at the foreshock. Bow shock profiles depend on the upstream Mach number, on shock geometry with respect to the upstream magnetic field, and on the plasma beta. Mercury's bow shock is weaker than Earth's with a Mach number MA ˜ 3, and is 10 times smaller. Thus, a more laminar shock is expected and a less complex foreshock may develop. A preliminary study has shown the existence of at least three types of waves: 1) whistler waves at frequencies near 2 Hz; 2) waves with frequencies ~ 0.1 Hz; 3) fluctuations with broad spectral peaks centered at ~ 0.6 Hz. Whistler waves propagate at angles up to 30 degrees, and lower frequency waves are more parallel propagating. We investigate wave properties such as polarization, ellipticity and compressibility. We also discuss wave origin and evolution. While whistler waves may be generated at the bow shock, the origin of lower frequency waves can be attributed to local generation by kinetic ion-ion instabilities. Due to the small scale size of Mercury's foreshock it is possible that waves suffer less steepening than at Earth.

  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 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.

  6. 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.

  7. Shock compression of [001] single crystal silicon

    DOE PAGESBeta

    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

  8. 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.

  9. 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.

  10. Analyzing Ramp Compression Wave Experiments

    NASA Astrophysics Data System (ADS)

    Hayes, D. B.

    2007-12-01

    Isentropic compression of a solid to 100's of GPa by a ramped, planar compression wave allows measurement of material properties at high strain and at modest temperature. Introduction of a measurement plane disturbs the flow, requiring special analysis techniques. If the measurement interface is windowed, the unsteady nature of the wave in the window requires special treatment. When the flow is hyperbolic the equations of motion can be integrated backward in space in the sample to a region undisturbed by the interface interactions, fully accounting for the untoward interactions. For more complex materials like hysteretic elastic/plastic solids or phase changing material, hybrid analysis techniques are required.

  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. Compression ignition of hydrogen-containing mixtures in shock tubes

    NASA Astrophysics Data System (ADS)

    Medvedev, S. P.; Gelfand, B. E.; Khomik, S. V.; Agafonov, G. L.

    2010-12-01

    The state of the art of the problem of discrepancy between the values measured in shock tubes and calculated for the delay of ignition of hydrogen-containing systems has been analyzed. It is shown that in the low-temperature region the off-design appearance of reaction sites leads to the propagation of a flame in a mixture heated by a reflected shock wave. The parameter of the time of mixture combustion in a deflagration regime has been introduced and the use of it together with the calculated delay in self-ignition for delimitation and classification of thermal and gas-dynamic phenomena on compression ignition of hydrogen-containing mixtures in shock tubes has been suggested.

  13. Kinematical Compatibility Conditions for Vorticity Across Shock Waves

    NASA Astrophysics Data System (ADS)

    Baty, Roy

    2015-11-01

    This work develops the general kinematical compatibility conditions for vorticity across arbitrary shock waves in compressible, inviscid fluids. The vorticity compatibility conditions are derived from the curl of the momentum equation using singular distributions defined on two-dimensional shock wave surfaces embedded in three-dimensional flow fields. The singular distributions are represented as generalized differential operators concentrated on moving shock wave surfaces. The derivation of the compatibility conditions for vorticity requires the application of second-order generalized derivatives and elementary tensor algebra. The well-known vorticity jump conditions across a shock wave are then shown to follow from the general kinematical compatibility conditions for vorticity by expressing the flow field velocity in vectorial components normal and tangential to a shock surface.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  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. 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.

  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. 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.

  3. 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.

  4. 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.

  5. Computation of Thermally Perfect Oblique Shock Wave Properties

    NASA Technical Reports Server (NTRS)

    Tatum, Kenneth E.

    1997-01-01

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

  6. 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. 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.

  8. Inelastic response of silicon to shock compression

    NASA Astrophysics Data System (ADS)

    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.

    2016-04-01

    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.

  9. 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

  10. 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

  11. Inelastic response of silicon to shock compression

    DOE PAGESBeta

    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

  12. (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.

  13. Fundamental structure of steady plastic shock waves in metals

    NASA Astrophysics Data System (ADS)

    Molinari, A.; Ravichandran, G.

    2004-02-01

    The propagation of steady plane shock waves in metallic materials is considered. Following the constitutive framework adopted by R. J. Clifton [Shock Waves and the Mechanical Properties of Solids, edited by J. J. Burke and V. Weiss (Syracuse University Press, Syracuse, N.Y., 1971), p. 73] for analyzing elastic-plastic transient waves, an analytical solution of the steady state propagation of plastic shocks is proposed. The problem is formulated in a Lagrangian setting appropriate for large deformations. The material response is characterized by a quasistatic tensile (compression) test (providing the isothermal strain hardening law). In addition the elastic response is determined up to second order elastic constants by ultrasonic measurements. Based on this simple information, it is shown that the shock kinetics can be quite well described for moderate shocks in aluminum with stress amplitude up to 10 GPa. Under the later assumption, the elastic response is assumed to be isentropic, and thermomechanical coupling is neglected. The model material considered here is aluminum, but the analysis is general and can be applied to any viscoplastic material subjected to moderate amplitude shocks. Comparisons with experimental data are made for the shock velocity, the particle velocity and the shock structure. The shock structure is obtained by quadrature of a first order differential equation, which provides analytical results under certain simplifying assumptions. The effects of material parameters and loading conditions on the shock kinetics and shock structure are discussed. The shock width is characterized by assuming an overstress formulation for the viscoplastic response. The effects on the shock structure of strain rate sensitivity are analyzed and the rationale for the J. W. Swegle and D. E. Grady [J. Appl. Phys. 58, 692 (1985)] universal scaling law for homogeneous materials is explored. Finally, the ability to deduce information on the viscoplastic response of

  14. 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.

  15. Propagation of shock waves through petroleum suspensions

    NASA Astrophysics Data System (ADS)

    Mukuk, K. V.; Makhkamov, S. M.; Azizov, K. K.

    1986-01-01

    Anomalous shock wave propagation through petroleum with a high paraffin content was studied in an attempt to confirm the theoretically predicted breakdown of a forward shock wave into oscillating waves and wave packets as well as individual solitons. Tests were performed in a shock tube at 10, 20, and 50 to 60 C, with pure kerosene as reference and with kerosene + 5, 10, 15, and 20% paraffin. The addition of paraffin was found to radically alter the rheodynamic characteristics of the medium and, along with it, the pattern of shock wave propagation. The integro-differential equation describing a one dimensional hydraulic shock process in viscoelastic fluids is reduced to the Burgers-Korteweg-deVries equation, which is solved numerically for given values of the system parameters. The results indicate that the theory of shock wave propagation through such an anomalous suspension must be modified.

  16. 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.

  17. 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.

  18. 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.

  19. Oblique interaction of waves with shocks

    NASA Astrophysics Data System (ADS)

    Morro, A.

    The oblique interaction between plane waves and shocks in materials described by a system of conservation equations is investigated. Two results are found. First, a straightforward geometric-kinematic analysis of the interaction yields a relation for each emergent mode (i.e., the outgoing wave) which determines the relation of propagation once the incident wave is given. Second, the shock may undergo an angular velocity which is ultimately related to the shock acceleration

  20. 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.

  1. 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.

  2. 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.

  3. In Situ Ellipsometry for Shock Compression Measurements

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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 α→ɛ phase transition.

  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. Shock compression of condensed matter using multimaterial reactive ghost fluid method

    NASA Astrophysics Data System (ADS)

    Kim, Ki-hong; Yoh, Jack J.

    2008-04-01

    For the flow analysis of reactive compressible media involving energetic materials and deforming metallic boundaries, a HYDRO-SCCM (shock compression of condensed matter) tool is developed for handling multiphysics shock analysis of energetic and inert matters. The highly energetic flows give rise to the strong nonlinear shock waves and the high strain rate deformation of solid boundaries at high pressure and temperature. For handling the large gradients associated with these complex flows in the condensed phase as well as in the reactive gaseous phase, a new Eulerian multifluid method is formulated. The numerical methodology is described in this paper, while the extended applications and the capacity of the tool are discussed in a separate paper [J. J. Yoh and K. H. Kim, "Shock Compression of Condensed Matter using Eulerian Multimaterial Method: Applications to multi-dimensional shocks, deflagration, detonation, and laser ablation," J. Appl. Phys. (accepted)].

  6. Substorm aurora and magnetic tail dynamics during interplanetary shock compression: THEMIS observations

    NASA Astrophysics Data System (ADS)

    Angelopoulos, Vassilis; Zhou, Xiaoyan

    2012-07-01

    Fast and forward interplanetary shocks compress and squeeze the Earth magnetosphere and cause a series of magnetospheric and ionospheric reactions. In addition to the enhancement of chorus, electromagnetic ion cyclotron (EMIC) waves and magnetospheric hiss, the ionospheric convection is enhanced as well. Shock aurora is generated, which is a phenomenon first an auroral brightness onset near local noon right after the shock impingement then followed by a fast anti-sunward auroral propagation along the oval. It has been found that substorm auroral activity can be significantly intensified by the shock compression when the shock upstream magnetic field was in southward in a certain period of time. This paper will present recent results based on the THEMIS spacecraft and ground-based observations. With multiple spacecraft in the magnetotail, the complex dynamics of the compressed tail is identified and analyzed. Correlations between the tail dynamics and substorm auroral variations will be discussed. *On-leave from Jet Propulsion Laboratory

  7. The role of divergences for shock waves

    NASA Astrophysics Data System (ADS)

    Uribe, Francisco

    2013-11-01

    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 applied them to study shock waves in dilute gases. Different theoretical descriptions for shock waves are mentioned and some of them are compared with experimental data and computer simulations. Our goal is to derive conditions under which the shock wave problem has a solution by analyzing the singularities of the vector field.

  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. PMID:27493993

  10. Implications of pressure diffusion for shock waves

    NASA Technical Reports Server (NTRS)

    Ram, Ram Bachan

    1989-01-01

    The report deals with the possible implications of pressure diffusion for shocks in one dimensional traveling waves in an ideal gas. From this new hypothesis all aspects of such shocks can be calculated except shock thickness. Unlike conventional shock theory, the concept of entropy is not needed or used. Our analysis shows that temperature rises near a shock, which is of course an experimental fact; however, it also predicts that very close to a shock, density increases faster than pressure. In other words, a shock itself is cold.

  11. A computer program for the 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.; Bishop, A. R.

    1978-01-01

    The calculation procedure is based on the method of characteristics for steady three-dimensional flow. The bow shock wave and the internal shock wave system were computed using a discrete shock wave fitting procedure. The general structure of the computer program is discussed, and a brief description of each subroutine is given. All program input parameters are defined, and a brief discussion on interpretation of the output is provided. A number of sample cases, complete with data deck listings, are presented.

  12. 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.

  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. 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.

  15. Shock Wave Technology and Application: An Update☆

    PubMed Central

    Rassweiler, Jens J.; Knoll, Thomas; Köhrmann, Kai-Uwe; McAteer, James A.; Lingeman, James E.; Cleveland, Robin O.; Bailey, Michael R.; Chaussy, Christian

    2012-01-01

    Context The introduction of new lithotripters has increased problems associated with shock wave application. Recent studies concerning mechanisms of stone disintegration, shock wave focusing, coupling, and application have appeared that may address some of these problems. Objective To present a consensus with respect to the physics and techniques used by urologists, physicists, and representatives of European lithotripter companies. Evidence acquisition We reviewed recent literature (PubMed, Embase, Medline) that focused on the physics of shock waves, theories of stone disintegration, and studies on optimising shock wave application. In addition, we used relevant information from a consensus meeting of the German Society of Shock Wave Lithotripsy. Evidence synthesis Besides established mechanisms describing initial fragmentation (tear and shear forces, spallation, cavitation, quasi-static squeezing), the model of dynamic squeezing offers new insight in stone comminution. Manufacturers have modified sources to either enlarge the focal zone or offer different focal sizes. The efficacy of extracorporeal shock wave lithotripsy (ESWL) can be increased by lowering the pulse rate to 60–80 shock waves/min and by ramping the shock wave energy. With the water cushion, the quality of coupling has become a critical factor that depends on the amount, viscosity, and temperature of the gel. Fluoroscopy time can be reduced by automated localisation or the use of optical and acoustic tracking systems. There is a trend towards larger focal zones and lower shock wave pressures. Conclusions New theories for stone disintegration favour the use of shock wave sources with larger focal zones. Use of slower pulse rates, ramping strategies, and adequate coupling of the shock wave head can significantly increase the efficacy and safety of ESWL. PMID:21354696

  16. Shock wave interaction with laser-generated single bubbles.

    PubMed

    Sankin, G N; Simmons, W N; Zhu, S L; Zhong, P

    2005-07-15

    The interaction of a lithotripter shock wave (LSW) with laser-generated single vapor bubbles in water is investigated using high-speed photography and pressure measurement via a fiber-optic probe hydrophone. The interaction leads to nonspherical collapse of the bubble with secondary shock wave emission and microjet formation along the LSW propagation direction. The maximum pressure amplification is produced during the collapse phase of the bubble oscillation when the compressive pulse duration of the LSW matches with the forced collapse time of the bubble. PMID:16090745

  17. Shock Wave Interaction with Laser-Generated Single Bubbles

    NASA Astrophysics Data System (ADS)

    Sankin, G. N.; Simmons, W. N.; Zhu, S. L.; Zhong, P.

    2005-07-01

    The interaction of a lithotripter shock wave (LSW) with laser-generated single vapor bubbles in water is investigated using high-speed photography and pressure measurement via a fiber-optic probe hydrophone. The interaction leads to nonspherical collapse of the bubble with secondary shock wave emission and microjet formation along the LSW propagation direction. The maximum pressure amplification is produced during the collapse phase of the bubble oscillation when the compressive pulse duration of the LSW matches with the forced collapse time of the bubble.

  18. Experimental and computational studies of two-dimensional compressible vortex-shock interaction

    NASA Astrophysics Data System (ADS)

    Kao, Chun-Teh

    The problem of two-dimensional compressible vortex-shock interaction is studied both experimentally and numerically. On the experimental side, a strong compressible vortex and a shock wave are produced in the open test section of a shock tube. The shock wave of strength M ≈ 1.2 then collides with the vortex that possesses a density drop at the vortex center exceeding 60% of the free stream value. Shadowgraphs and schlieren pictures of the event are taken in a sequence of experiments with progressive time delays. The pictures show that the shock profile is significantly modified by the interaction, with substantial distortion, disconnection, and a local nonlinear focusing structure. In the computational work, both the Euler equations and the Navier-Stokes equations are solved to simulate the problem. Two flux-splitting techniques are employed: (1) first-order-accurate Modified Steger-Warming method and (2) second-order-accurate variable-extrapolation method satisfying the total-variation-diminishing (TVD) condition. Based on the numerical data, the respective behaviors of the vortex, the shock wave, and the secondary wave generated during the interaction are analyzed. The simulation also reveals that the focal region of the distorted shock structure is bounded by a Mach stem and two slipstreams, in which local intensified pressure, density, and temperature peaks occur. It is found that the local intensification of fluid properties and the secondary wave possess essentially nonlinear characteristics at their early stages. The computational results agree well, qualitatively, with the experimental observations.

  19. 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.

  20. Noise transmission along shock-waves

    NASA Astrophysics Data System (ADS)

    Amur Varadarajan, Prasanna

    Shocks at the inlet of scramjet engines are subject to perturbations from their interaction with turbulent boundary layer. DNS results for this interaction indicate the presence of discrete vortices that interact with the shock at its foot. These studies reveal that the vortices cause oscillations of the shock. In this work we examine the propagation of disturbances along a stationary oblique shock following interaction with a two-dimensional vortex. We study the decay of disturbances along a normal shock as measured from Euler computations and compare these with the predictions of Geometrical Shock Dynamics (GSD) for long range propagation. We have incorporated two improvements into the GSD model to tackle the shock-vortex interaction problem. The wave structure of the disturbance resembles N waves, the decay of which follows a power law profile. An extension of the GSD model to predict shock surface propagation in 3-D flows is presented along with the numerical implementation.

  1. 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].

  2. Clinical application of extracorporeal shock wave therapy in orthopedics: focused versus unfocused shock waves.

    PubMed

    Foldager, Casper Bindzus; Kearney, Cathal; Spector, Myron

    2012-10-01

    For the past decade extracorporeal shock wave therapy has been applied to a wide range of musculoskeletal disorders. The many promising results and the introduction of shock wave generators that are less expensive and easier to handle has added to the growing interest. Based on their nature of propagation, shock waves can be divided into two types: focused and unfocused. Although several physical differences between these different types of shock waves have been described, very little is known about the clinical outcome using these different modalities. The aim of the present review is to investigate differences in outcome in select orthopaedic applications using focused and unfocused shock waves. PMID:22920552

  3. A midsummer-night's shock wave

    NASA Astrophysics Data System (ADS)

    Hargather, Michael; Liebner, Thomas; Settles, Gary

    2007-11-01

    The aerial pyrotechnic shells used in professional display fireworks explode a bursting charge at altitude in order to disperse the ``stars'' of the display. The shock wave from the bursting charge is heard on the ground as a loud report, though it has by then typically decayed to a mere sound wave. However, viewers seated near the standard safety borders can still be subjected to weak shock waves. These have been visualized using a large, portable, retro-reflective ``Edgerton'' shadowgraph technique and a high-speed digital video camera. Images recorded at 10,000 frames per second show essentially-planar shock waves from 10- and 15-cm firework shells impinging on viewers during the 2007 Central Pennsylvania July 4th Festival. The shock speed is not measurably above Mach 1, but we nonetheless conclude that, if one can sense a shock-like overpressure, then the wave motion is strong enough to be observed by density-sensitive optics.

  4. Spherical shock waves in general relativity

    SciTech Connect

    Nutku, Y. )

    1991-11-15

    We present the metric appropriate to a spherical shock wave in the framework of general relativity. This is a Petrov type-{ital N} vacuum solution of the Einstein field equations where the metric is continuous across the shock and the Riemann tensor suffers a step-function discontinuity. Spherical gravitational waves are described by type-{ital N} Robinson-Trautman metrics. However, for shock waves the Robinson-Trautman solutions are unacceptable because the metric becomes discontinuous in the Robinson-Trautman coordinate system. Other coordinate systems that have so far been introduced for describing Robinson-Trautman solutions also suffer from the same defect. We shall present the {ital C}{sup 0}-form of the metric appropriate to spherical shock waves using Penrose's approach of identification with warp. Further extensions of Penrose's method yield accelerating, as well as coupled electromagnetic-gravitational shock-wave solutions.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Shock Compression of Beryllium Single Crystals: Time-Dependent, Anisotropic Elastic-Plastic Response

    NASA Astrophysics Data System (ADS)

    Winey, J.; Gupta, Y.

    2013-06-01

    To gain insight into inelastic deformation mechanisms in shocked Be single crystals, wave propagation simulations were performed for crystals shocked along the c-axis, a-axis, and other crystal directions to peak stresses reaching 7 GPa. The simulations utilized a time-dependent, anisotropic material model that incorporated dislocation dynamics and deformation twinning based descriptions of inelastic deformation. The simulation results showed good qualitative agreement with the measured wave profiles, including features arising from wave mode coupling due to the highly anisotropic inelastic response of Be. The measured wave profiles can be understood in terms of dislocation slip along basal, prismatic, and pyramidal planes, together with deformation twinning. Our results provide insight into the complex nature of inelastic deformation in shocked Be, and are also expected to be valuable for understanding the anisotropic inelastic response of analogous hcp metals subjected to shock compression. Work supported by ARL and DOE/NNSA.

  10. Unsteady Phenomena in Shock Wave/Boundary Layer Interaction

    NASA Technical Reports Server (NTRS)

    Dolling, D. S.

    1993-01-01

    A brief review is given of the unsteadiness of shock wave/turbulent boundary layer interaction. The focus is on interactions generated by swept and unswept compression ramps, by flares, steps and incident shock waves, by cylinders and blunt fins, and by glancing shock waves. The effects of Mach number, Reynolds number, and separated flow scale are discussed as are the physical causes of the unsteadiness. The implications that the unsteadiness has for interpreting time-average surface and flowfield data, and for comparisons of such experimental data with computation, is also briefly discussed. Finally, some suggestions for future work are given. It is clear that there are large gaps in the data base and that many aspects of such phenomena are poorly understood. Much work remains to be done.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Synthesis of submicron metastable phase of silicon using femtosecond laser-driven shock wave

    SciTech Connect

    Tsujino, Masashi; Sano, Tomokazu; Sakata, Osami; Ozaki, Norimasa; Kodama, Ryosuke; Kimura, Shigeru; Takeda, Shingo; Kobayashi, Kojiro F.; Hirose, Akio

    2011-12-15

    We measured the grain size of metastable phase of Si synthesized by shock compression. We analyzed the crystalline structures of the femtosecond laser-driven shock compressed silicon with x-ray diffraction measurements. We found that submicron grains of metastable Si-VIII exist in the silicon. We suggest that the pressure loading time is too short for the nucleated high-pressure phases to grow in case of the femtosecond laser-driven shock compression, therefore Si-VIII grains of submicron size are obtained. We are expecting to discover other unique crystalline structures induced by the femtosecond laser-driven shock wave.

  19. Magnetohydrodynamic shock waves in molecular clouds

    SciTech Connect

    Draine, B.T.; Roberge, W.G.; Dalgarno, A.

    1983-01-15

    The structure of shock waves in molecular clouds is calculated, including the effects of ion-neutral streaming driven by the magnetic field. It is found that shock waves in molecular clouds will usually be C-type shock waves, mediated entirely by the dissipation accompanying ion-neutral streaming, and in which all of the hydrodynamic variables are continuous. Detailed results are presented for magnetohydrodynamic shock waves propagating at speeds in the range of 5--50 km s/sup -1/ in molecular clouds with preshock densities n/sub H/ = 10/sup 2/, 10/sup 4/, and 10/sup 6/ cm/sup -3/. Graphs are constructed of the effective ''excitation temperatures'' of the rotational and vibrational levels of H/sub 2/ in the shocked gas. The effects of chemical changes in the composition of oxygen-bearing molecules are investigated, and the contributions to the cooling of the shocked gas by emission from H/sub 2/, CO, OH, and H/sub 2/O are evaluated. Predictions are made of the intensities of the rotation-vibration lines of H/sub 2/ and of the fine-structure lines of O I and C I. Magnetic fields may lead to a substantial increase in the limiting shock velocity above which dissociation of H/sub 2/ takes place: for a cloud of density eta/sub H/ = 10/sup 6/ cm/sup -3/, the limiting shock speed is approx.45 km s/sup -1/. The fractional ionization is a critical parameter affecting the shock structure, and the processes acting to change the ionization in the shock are examined. Magnetic field effects enhance the sputtering of grain mantles in dense gas: H/sub 2/O ice mantles can be substantially eroded in v/sub s/> or =25 km s/sup -1/ shock waves. Grain erosion may contribute to the enhancement of some molecular species in the shocked gas.

  20. 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.

  1. Ion acoustic shock waves in degenerate plasmas

    SciTech Connect

    Akhtar, N.; Hussain, S.

    2011-07-15

    Korteweg de Vries Burgers equation for negative ion degenerate dissipative plasma has been derived using reductive perturbation technique. The quantum hydrodynamic model is used to study the quantum ion acoustic shock waves. The effects of different parameters on quantum ion acoustic shock waves are studied. It is found that quantum parameter, electrons Fermi temperature, temperature of positive and negative ions, mass ratio of positive to negative ions, viscosity, and density ratio have significant impact on the shock wave structure in negative ion degenerate plasma.

  2. 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.

  3. 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.

  4. Shock wave dispersion in weakly ionized gas

    NASA Astrophysics Data System (ADS)

    Kessaratikoon, Prasong

    2003-10-01

    Electrodeless microwave (MW) discharge in two straight, circular cylindrical resonant cavities in TE1,1,1 and TM0,1,2 modes were introduced to perform additional experimental studies on shock wave modification in non-equilibrium weakly ionized gases and to clarify the physical mechanisms of the shock wave modification process. The discharge was generated in 99.99% Ar at a gas pressure between 20 and 100 Torr and at a discharge power density less than 10.0 Watts/cm3. Power density used for operating the discharge was rather low in the present work, which was determined by evaluating the power loss inside the resonant cavity. It was found that the shock wave deflection signal amplitude was decreased while the shock wave local velocity was increased in the presence of the discharge. However, there was no apparent evidence of the multiple shock structure or the widening of the shock wave deflection signal, as observed in the d.c. glow discharge [3,5]. The shock wave always retained a more compact structure even in the case of strong dispersion in both the TE and the TM mode. The shock wave propagated faster through the discharge in the TE mode than in the TM mode. Discharge characteristics and local parameters such as gas temperature T g, electron density Ne, local electric field E, and average power density, were determined by using the MW discharge generated from an Argon gas mixture that contains 95% Ar, 5% H2, and traces of N2. The gas temperature was evaluated by using the amplitude reduction technique and the emission spectroscopy of Nitrogen. The gas temperature distribution was flat in the central region of the cavity. By comparing the gas temperature calculated from the shock wave local velocity and from the amplitude reduction technique, the present work was sufficiently accurate to indicate that the thermal effect is dominant. The electron density was obtained from measured line shapes of hydrogen Balmer lines by using the gas temperature and the well

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. Shock waves on complex networks.

    PubMed

    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

  10. The physics of interstellar shock waves

    NASA Technical Reports Server (NTRS)

    Shull, J. Michael; Draine, Bruce T.

    1987-01-01

    This review discusses the observations and theoretical models of interstellar shock waves, in both diffuse cloud and molecular cloud environments. It summarizes the relevant gas dynamics, atomic, molecular and grain processes, radiative transfer, and physics of radiative and magnetic precursors in shock models. It then describes the importance of shocks for observations, diagnostics, and global interstellar dynamics. It concludes with current research problems and data needs for atomic, molecular and grain physics.

  11. Shock compaction of magnet powder using underwater shock wave

    SciTech Connect

    Kubota, Shiro; Fujita, Masahiro; Itoh, Shigeru

    1996-12-31

    In order to get a high plug density (over 90%), the authors tried a direct consolidation of the magnet powder using the converging underwater shock wave created by the underwater explosion of explosives. The processes of the consolidation of the magnet powder were investigated by numerical calculation. They obtained the parameters of the EOS (Petrie-Page model) for Magnet powder using quasi-static loading experiments. Moreover, the characteristics of the shock compaction assembly were also verified.

  12. 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.

  13. Beamwidth measurement of individual lithotripter shock waves

    PubMed Central

    Kreider, Wayne; Bailey, Michael R.; Ketterling, Jeffrey A.

    2009-01-01

    New lithotripters with narrower foci and higher peak pressures than the original Dornier HM3 electrohydraulic lithotripter have proven to be less effective and less safe. Hence, accurate measurements of the focal characteristics of lithotripter shock waves are important. The current technique for measuring beamwidth requires a collection of single-point measurements over multiple shock waves, thereby introducing error as a result of any shock-to-shock variability. This work reports on the construction of a hydrophone array sensor and on array measurements of individual lithotripter shock waves. Beamwidths for an electrohydraulic lithotripter with a broad-focus HM3-style reflector and a narrow-focus modified reflector were measured using both new and worn electrodes as well as two different electrical charging potentials. The array measured the waveform, beamwidth, and focal location of individual shock waves. The HM3-style reflector produced repeatable focal waveforms and beam profiles at an 18 kV charging potential with new and worn electrodes. Corresponding measurements suggest a narrower beamwidth than reported previously from averaged point measurements acquired under the same conditions. In addition, a lack of consistency in the measured beam profiles at 23 kV underscores the value of measuring individual shock waves. PMID:19206897

  14. Shock wave diagnostics using fluorescent dye probes

    NASA Astrophysics Data System (ADS)

    Banishev, Alexandr; Christensen, James; Dlott, Dana

    2015-06-01

    Fluorescent probes are highly developed, and have found increasing use in a wide variety of applications. We have studied shock compression of various materials with embedded dye probes used as high speed probes of pressure and temperature. Under the right conditions, dye emission can be used to make a map of the pressure distribution in shocked microstructured materials with high time (1 ns) and space (1 micrometer) resolution. In order to accomplish this goal, we started by studying shock compression of PMMA polymer with rhodamine 6G dye (R6G), as a function of shock pressure and shock duration. We observed the shock-induced spectral redshift and the shock-induced intensity loss. We investigated the fundamental mechanisms of R6G response to pressure. We showed that the time response of a dye probe is limited by its photophysical behavior under shock. We developed superemissive ultrafast dye probes by embedding R6G in a silica nanoparticle. More recently, we have searched for dye probes that have better responses. For instance, we have found that the dye Nile Red embedded in the right polymer matrix has 1.7 times larger pressure-induced redshift than R6G.

  15. 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.

  16. Emission lines and shock waves in RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Gillet, D.; Fokin, A. B.

    2014-05-01

    Context. Emission lines observed in radially pulsating stars are thought to be produced by atoms de-exciting after being excited by a shock wave that is traveling into and then compressing, heating, and accelerating the atmospheric gas. Aims: With the help of recent observations, we examine the origin of all the different types of emission lines of hydrogen and helium that appear during a pulsation cycle. Methods: To analyze the physical origin of emission lines, we used the different models of atmospheric dynamics of RR Lyrae stars that have been calculated so far. Results: In contrast to a recent explanation, we propose that the redshifted emission component of Hα, which occurs near the pulsation phase 0.3, is produced by the main shock. In this case, the emission is the natural consequence of the large extension of the expanding atmosphere. Therefore, this (weak) emission should only be observed in RR Lyrae stars for which the main shock will propagate far enough from the photosphere. It appears as a P-Cygni type profile. We estimate the shock front velocity during the shock propagation in the atmosphere and show that it decreases by 40% when the Hα emitting-shock passes from the photospheric level to the upper atmosphere. The Hα P-Cygni profile observed in long-period Cepheids also seems to be caused by the main shock wave. Although to date He II has only been detected in some Blazhko stars, a comprehensive survey of RR Lyrae stars is necessary to confirm this trend, so we can say that the most intense shocks will only be observed in Blazhko stars. Conclusions: The development of a model of atmospheric pulsation that takes the effects of 2D and 3D convection into account, seems to be a necessary step to fully quantify the effects of shock waves on the atmospheric dynamics of radially pulsating stars.

  17. Shock wave sensors: I. Requirements and design.

    PubMed

    Lewin, P A; Schafer, M E

    1991-01-01

    In the last 9 years, extracorporeal shock wave lithotripsy has become one of the preferred procedures for the treatment of urinary and gallbladder calculi. While there is still uncertainty as to the mechanisms of stone fragmentation, current hypotheses suggest that acoustical shock wave parameters such as rise time, peak compressional and rarefactional pressure, and frequency content may all influence the treatment's efficiency. Thus, optimization of lithotripsy treatment needs pressure sensors that can adequately characterize the shock wave field. This article presents and discusses the design of reliable, wideband, quantitative shock wave sensors made of piezoelectric material. The development, design, and performance characteristics of the sensors are presented. Sensor construction details are described, as are the methods used to characterize the sensor's acoustical performance. The key acoustical parameters of the sensor, its frequency response, and directivity pattern are presented; theory indicates that the probes feature uniform sensitivity over the frequency range up to 100 MHz. Preliminary experimental results indicate that piezoelectric polymer sensors made of polyvinylidene fluoride (PVDF) with a low acoustical impedance backing are suitable for lithotripter field measurements. The applicability of sensors based on fiber optics to shock wave measurements is also briefly discussed. In a companion article, shock wave measurement techniques are outlined and selected lithotripter test data are presented. PMID:10149140

  18. 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.

  19. Jump in the electrical conductivity of shock-compressed glassy carbon

    NASA Astrophysics Data System (ADS)

    Molodets, A. M.; Golyshev, A. A.; Emel'yanov, A. N.; Shul'ga, Yu. M.; Fortov, V. E.

    2014-04-01

    The effect of high dynamic pressures on the electrical conductivity of the amorphous conducting carbon phase (glassy carbon) has been studied. The electrical conductivity of glassy carbon samples has been measured under the condition of shock compression and subsequent release wave. The history of the shock loading of glassy carbon has been calculated with the developed semiempirical equations of state. It has been shown the electrical conductivity of glassy carbon samples in the compression phase at a pressure of 45(5) GPa decreases abruptly by two orders of magnitude. In the relief phase, partially reversible change in the electrical conductivity of an amorphous carbon sample occurs. The recorded effect has been treated as a result of a partially reversible physicochemical transformation of shock-compressed amorphous carbon.

  20. 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.

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Attenuation and distortion of compression waves propagating in very long tube

    NASA Astrophysics Data System (ADS)

    Nakamura, Shinya; Sasa, Daisuke; Aoki, Toshiyuki

    2011-03-01

    A lot of phenomena related to propagating various waves are seen when the high-speed train goes through the tunnel, the gas pipeline is broken due to an accident or the air brake of the wagon operates. For instance, a compression wave generated ahead of a high-speed train entering a tunnel propagates to the tunnel exit and spouts as a micro pressure wave, which causes an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a compression wave propagating along a very long tunnel must be understood and the experimental information on these phenomena is required. An experimental investigation is carried out to clarify the attenuation and distortion of the propagating compression wave in a very long tube. Experimental results show that the strength of a compression wave decreases with distance. The attenuation and distortion of compression waves are affected by the initial waveform of the compression wave and by the unsteady boundary layer induced by the propagating wave. The shape of a compression wave becomes different with the propagating distance; that is, a shock wave appears just head of a wavefront and an overshoot on pressure distribution is observed behind a shock wave due to the transition of the unsteady boundary layer.

  5. 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.

  6. 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.

  7. A New Acoustic Lens Design for Electromagnetic Shock Wave Lithotripters

    NASA Astrophysics Data System (ADS)

    Zhong, Pei; Smith, Nathan; Simmons, Neal W.; Sankin, Georgy

    2011-09-01

    The 3rd-generation electromagnetic (EM) shock wave lithotripters often have narrow focal width and high peak pressure compared to the original Dornier HM-3. In addition, the pressure waveform produced by a typical EM lithotripter has a secondary compressive wave following the tensile component that suppresses lithotripter pulse induced cavitation, which may impact negatively on stone comminution. These characteristic changes in the modern EM lithotripters may contribute in part to their reduced effectiveness observed clinically. To overcome these two drawbacks, we have designed a new acoustic lens for the Siemens Modularis EM lithotripter that produces an idealized pressure waveform similar to that of the HM-3 with broad focal width and low peak pressure. At acoustic pulse energy of 53 mJ, the new lens design enlarges the -6 dB focal width of the Modularis by 47% while significantly reducing the second compressive wave in the lithotripter pulse throughout its focal plane. After 2000 shocks, in vitro comminution produced by the original and new lens designs are 100% and 99% at the lithotripter focus, and 52±16% and 77±8% (p<0.001) at 10 mm off axis, respectively. Corresponding values for stones that are translated to mimic respiratory motion during shock wave lithotripsy are 83±4% and 91±1% (p<0.01), demonstrating the significant performance improvement provided by the new lens design.

  8. Elastic properties of metals and minerals under shock compression

    SciTech Connect

    Duffy, T.S.

    1992-01-01

    Comparison of laboratory elasticity data with seismic measurements of the Earth provides a means to understand the deep interior. In this work, elastic wave velocities have been measured under shock compression to 80 GPa in an Fe-Cr-Ni alloy, to 27 GPa in polycrystalline MgO, and to 81 GPa in molybdenum preheated to 1400[degrees]C. These measurements were made by recording particle velocity histories at a sample surface using the method of velocity interferometry. Compressional and bulk wave velocities in Fe-Cr-Ni alloy are consistent with third-order finite strain theory and ultrasonic data. The measured wave profiles can be successfully reproduced by numerical simulations utilizing elastic-plastic theory modified by a Bauschinger effect and stress relaxation. Material strength was found to increase by a factor of at least 5 up to 80 GPa and to be 2-3% of the total stress. Compressional and bulk velocities in Fe-Cr-Ni define linear velocity-density trends and can be modeled by averaging properties of Fe, Cr, and Ni. The effect of alloying [approximately]4 wt.% Ni with Fe would change both V[sub P] and V[sub B] by less than 1% under Earth's core conditions. Compressional and shear velocities in Fe-Ni are compatible with inner core values when corrected for thermal effects. Wave profile and EOS measurements in polycrystalline MgO define its EOS: U[sub S] = 6.77(0.08) + 1.27(0.04)[mu][sub p]. Compressional sound velocities to 27 GPa yield a longitudinal modulus and its pressure derivative which are in good agreement with ultrasonic determinations. The unloading wave profiles can be modeled using a modified elastic-plastic constitutive response originally developed for metals. Thermal expansivities in MgO have been determined to be 12 [+-] 14 [times] 10[sup [minus]6] K[sup [minus]1] at P = 174-200 GPa and T = 3100-3600 K from shock temperature and EOS data. These results imply that the Earth's lower mantle is enriched in Si and/or Fe relative to the upper mantle.

  9. 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

  10. 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.

  11. Turbulent Water Coupling in Shock Wave Lithotripsy

    PubMed Central

    Lautz, Jaclyn; Sankin, Georgy; Zhong, Pei

    2013-01-01

    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). 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 s to 0.3 s by a jet with an exit velocity of 62 cm/s. 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. PMID:23322027

  12. 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.

  13. 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

  14. 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.

  15. Shock wave loading of a magnetic guide

    NASA Astrophysics Data System (ADS)

    Kindt, L.

    2011-10-01

    velocities and a shock wave is created between the two velocity regions. In order to conserve number of particle, momentum and enthalpy the density of the atomic beam passing through the shock wave must increase. We have build such a shock wave in an atomic beam and observed the density increase due to this. As an extra feature having a subsonic beam on a downward slope adds an extra density increase due to gravitational compression. Loading ultra cold atoms into a 3D trap from the dense subsonic beam overcomes the problem with 2D cooling and thermal conductivity. This was done and evaporative cooling was applied creating an unprecedented large number rubidium BEC.

  16. 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.

  17. Nonplanar Shock Waves in Dusty Plasmas

    SciTech Connect

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

    2011-11-29

    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.

  18. 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.

  19. 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.

  20. Hypersonic flow separation in shock wave boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Hamed, A.; Kumar, Ajay

    1992-01-01

    An assessment is presented for the experimental data on separated flow in shock wave turbulent boundary layer interactions at hypersonic and supersonic speeds. The data base consists mainly of two dimensional and axisymmetric interactions in compression corners or cylinder-flares, and externally generated oblique shock 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 shock interaction are also presented and discussed.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Characterizing the Thermal History of Shock-Compressed Phyllosilicates

    NASA Astrophysics Data System (ADS)

    Spaulding, D.; Stewart, S. T.; Hankin, M.; Wizda, L.

    2013-12-01

    Phyllosilicates are known to be abundant on the surface of Mars and as matrix material in carbonaceous chondrites. It is important to understand the influence of shock processing on such materials because they are expected to play an important role in the preservation and transport of volatile chemical species. Shock effects may thus influence how volatiles are preferentially incorporated or lost during planetary accretion as well as spectral observations and interpretations of the aqueous history of planetary surfaces. Previous experiments have studied devolatilization of phyllosilicates under shock compression, though the role of temperature and the details of thermal alteration are poorly constrained. Here we measure the shock response (Hugoniot) and post-shock temperatures of Montmorillonite up to 23 GPa (shock velocities of 5.5 km/sec). We examine the relative importance of temperature and pressure for shock devolatilization and revisit the implications for the interpretation of previously published experiments. In addition, progress towards increasingly controlled shock recovery experiments is presented using the above equation of state, post-shock temperature data, and computational modeling of recovery capsule geometries.

  6. 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

  7. (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.

  8. Vorticity Transfer in Shock Wave Interactions with Turbulence and Vortices

    NASA Astrophysics Data System (ADS)

    Agui, J. H.; Andreopoulos, J.

    1998-11-01

    Time-dependent, three-dimensional vorticity measurements of shock waves interacting with grid generated turbulence and concentrated tip vortices were conducted in a large diameter shock tube facility. Two different mesh size grids and a NACA-0012 semi-span wing acting as a tip vortex generator were used to carry out different relative Mach number interactions. The turbulence interactions produced a clear amplification of the lateral and spanwise vorticity rms, while the longitudinal component remained mostly unaffected. By comparison, the tip vortex/shock wave interactions produced a two fold increase in the rms of longitudinal vorticity. Considerable attention was given to the vorticity source terms. The mean and rms of the vorticity stretching terms dominated by 5 to 7 orders of magnitude over the dilitational compression terms in all the interactions. All three signals of the stretching terms manifested very intermittent, large amplitude peak events which indicated the bursting character of the stretching process. Distributions of these signals were characterized by extremely large levels of flatness with varying degrees of skewness. These distribution patterns were found to change only slightly through the turbulence interactions. However, the tip vortex/shock wave interactions brought about significant changes in these distributions which were associated with the abrupt structural changes of the vortex after the interaction.

  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. 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.

  11. 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.

  12. Shock Compressing Diamond to a Conducting Fluid

    SciTech Connect

    Bradley, D K; Eggert, J H; Hicks, D G; Celliers, P M; Moon, S J; Cauble, R C; Collins, G W

    2004-07-29

    Laser generated shock reflectance data show that diamond undergoes a continuous transition from optically absorbing to reflecting between Hugoniot pressures 600

  13. Optical shock waves in silica aerogel.

    PubMed

    Gentilini, S; Ghajeri, F; Ghofraniha, N; Di Falco, A; Conti, C

    2014-01-27

    Silica aerogels are materials well suited for high power nonlinear optical applications. In such regime, the non-trivial thermal properties may give rise to the generation of optical shock waves, which are also affected by the structural disorder due to the porous solid-state gel. Here we report on an experimental investigation in terms of beam waist and input power, and identify various regimes of the generation of wave-breaking phenomena in silica aerogels. PMID:24515173

  14. 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.

  15. 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.

  16. Compression Shocks in Two-Dimensional Gas Flows

    NASA Technical Reports Server (NTRS)

    Busemann, A.

    1949-01-01

    The following are arguments on the compression shocks in gas flow start with a simplified representation of the results of the study made by Th. Meyer as published in the Forschungsheft 62 of the VDI, supplemented by several amplifications for the application.In the treatment of compression shocks, the equation of energy, the equation of continuity, the momentum equation, the equation of state of the particular gas, as well as the condition Of the second law of thermodynamics that no decrease of entropy is possible in an isolated system, must be taken into consideration. The result is that, in those cases where the sudden change of state according to the second law of thermodynamics is possible, there always occurs a compression of the gas which is uniquely determined by the other conditions.

  17. 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)

  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. 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.

  20. 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.

  1. Colliding electromagnetic shock waves in general relativity

    SciTech Connect

    Halilsoy, M.

    1988-04-15

    We derive a new, exact solution for the Einstein-Maxwell equations that describes the collision (interaction) of two arbitrarily polarized electromagnetic shock waves. In the limit that the polarization angle vanishes, our solution reduces to the Bell-Szekeres solution.

  2. Uncovering the Secret of Shock Wave Lithotripsy

    NASA Astrophysics Data System (ADS)

    Zhong, P.

    Shock wave lithotripsy (SWL) is an engineering innovation that has revolutionized the treatment of kidney stone disease since the early 1980s [1] - [3]. Today, SWL is the first-line therapy for millions of patients worldwide with renal and upper urinary stones [3, 4].

  3. 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.

  4. 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...

  5. 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...

  6. 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...

  7. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 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...

  8. 21 CFR 876.5990 - Extracorporeal shock wave lithotripter.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 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...

  9. Shock wave propagation in glow discharges

    NASA Astrophysics Data System (ADS)

    Ganguly, B. N.

    1998-10-01

    The modification of acoustic shock wave propagation characteristics in a 25 cm long positive column low pressure (10 to 50 Torr), low current density (2 to 10 mA/cm^2) argon and N2 dc discharges have been measured by laser beam deflection technique. The simultaneous multi point shock velocity, dispersion and damping have been measured both inside and outside the glow discharge region. The local shock velocity is found to increase with the increased propagation path length through the discharge; for Mach number greater than 1.7 the upstream velocity exceeded the downstream velocity in contrast to the opposite behavior in neutral gas. The damping and dispersion are also dependent on the propagation distance. The recovery of the shock dispersion and damping in the post discharge region, for a given discharge condition, are functions of the initial Mach number. The optical measurement of the wall and the gas (rotational) temperatures suggest the observed shock features can not be solely explained by the gas heating in a self sustained discharge. The results are similar for both Ar and N2 discharges showing that vibrational excitation and relaxation are not essential^1. The explanation of the observed weak shock propagation properties in a glow discharge appears to require long range cooperative interactions that enhance heavy particle collisional energy transfer rates for the measured discharge conditions. Unlike collisional shock wave propagation in highly ionized plasmas^2,3, the exact energy coupling mechanism between the nonequilibrium weakly ionized plasma and shock is not understood. 1. A.I. Osipov and A.V. Uvarov, Sov. Phys. Usp. 35, 903 (1992) and other references there in. 2. M. Casanova, O. Larroche and J-P Matte, Phys. Rev. Lett. 67, 2143 (1991). 3. M.C.M. van de Sanden, R. van den Bercken and D.C. Schram, Plasma Sources Sci.Technol. 3, 511 (1994).

  10. 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).

  11. Analysis of gas flow evolution and shock wave decay in detonation thermal spraying systems

    NASA Astrophysics Data System (ADS)

    Ramadan, K.; Butler, P. Barry

    2004-06-01

    The reactive Euler equations with variable gas properties are solved in both axisymmetric and plane two-dimensional flows to analyze the gas flow evolution, shock wave decay, and shock reflections in pulsed detonation thermal spraying (PDTS) systems. The gas phase governing equations are numerically solved using a high-resolution shock capturing numerical method. Expansion-compression waves are formed upon external gas expansion and persist for a long time (on the time scale of a PDTS cycle) with wide fluctuations in the gas velocity and temperature. The results show that the reflected shock wave from the substrate dies out extremely fast that micron-sized particles used in PDTS do not encounter these transients. The external shock wave decay is also analyzed for different reactive mixtures and flow geometries and is related to the truncation of the computational domain and the implementation of numerical boundary conditions at the open end boundaries.

  12. 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.

  13. Influence of the reversible α-ɛ phase transition and preliminary shock compression on the spall strength of armco iron

    NASA Astrophysics Data System (ADS)

    Garkushin, G. V.; Naumova, N. S.; Atroshenko, S. A.; Razorenov, S. V.

    2016-01-01

    Full wave profiles are used to determine the Hugoniot elastic limit and the spall strength of armco iron samples with an as-received structure and the samples recovered after preliminary loading by plane shock waves with an amplitude of 8, 17, and 35 GPa. The measurements are performed at a shock compression pressure below and above the polymorphic a-e transition pressure. Metallographic analysis of the structure of armco iron shows that a developed twinned structure forms inside grains in the samples subjected to preliminary compression and recovered and that the twin concentration and size increase with the shock compression pressure. The spall strength of armco iron under shock loading below the phase transition pressure increases by approximately 10% due to its preliminary deformation twinning at the maximum shock compression pressure. The spallation of samples with various structures at a shock compression pressure above the phase transition proceeds at almost the same tensile stresses. The polymorphic transition in armco iron weakly affects its strength characteristics.

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

    NASA Astrophysics Data System (ADS)

    Liu, Qingming; Zhang, Yunming

    2014-10-01

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

  15. Temperature kinetics during shock-wave consolidation of metallic powders

    SciTech Connect

    Schwarz, R.B.; Kasiraj, P.; Vreeland, T. Jr.

    1985-01-01

    Powders (60 ..mu..m diam) of constantan and pure copper were compressed statically into cylindrical greens (20.3 mm diam, 5.3 mm long) with a flat interface separating the two powders. A 20-mm propellant gun was used to accelerate a flyer of Lexan, copper, or aluminum, and generate in the green a shock wave with front parallel to the Cu/constantan interface. The voltages between opposite ends of the greens were measured as a function of time and for shock pressures between 1.3 and 9.4 GPa. When the shock wave arrives at the Cu/constantan interface, the voltage signal shows an abrupt increase, which lasts between 45 and 81 ns and leads to a peak temperature T/sub p/. After this, the hotter and cooler parts of the compact equilibrate and the temperature decreases to a value T/sub h/. With increasing shock pressure, T/sub h/ increases from 425 to 1215 K. The measurements of T/sub h/ are in excellent agreement with the temperatures calculated from the measured flyer velocity, the Hugoniot for copper powder, and thermodynamic data for the flyer and powders.

  16. Strength of titanium diboride under shock wave loading

    NASA Astrophysics Data System (ADS)

    Dandekar, Dattatraya P.; Benfanti, Daniel C.

    1993-01-01

    Strength of TiB2 under plane shock wave loading is assessed in terms of its spall threshold and the shear stress sustained by it under shock compression to 60 GPa. The results of experiments support the thesis that the observed cusp in TiB2 at 4.5-7.0 GPa is of mechanical nature and its effect is to decrease the spall threshold values at stresses above the cusp but below the accepted Hugoniot elastic limit (HEL) value of 13-17 GPa. A comparison of shock Hugoniot data on two different TiB2 obtained from Grady [Dynamic Material Properties of Armor Ceramics, Sandia Laboratories, SAND 91-0147. UC-704 (1991)] and the adiabats constructed from high pressure ultrasonic wave velocity measurements show that these materials sustain increasing shear stresses with increasing values of shock stress. For example, results of data analysis on the denser TiB2 show that it sustains around three times the shear stress at 60 GPa than at its HEL, i.e., 17 GPa.

  17. 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.

  18. 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

  19. Reflectivities of Four Shock-Compressed Alkali Halides

    NASA Astrophysics Data System (ADS)

    Diamond, M. R.; McWilliams, R. S.; Eggert, J.; Jeanloz, R.; Ali, S. J.; Collins, G. W.

    2015-12-01

    Laser-shock compression on four alkali halides has been used to probe the transition from insulating to metallic states, a high-pressure transition in chemical bonding that has fundamental implications for planetary formation and structure. Collectively, pressures up to 450 GPa and densities up to three-fold compression were explored across a total of fourteen single-crystal samples of CsI, CsBr, KBr and NaCl. Velocity interferometry was used to record shock velocities and reflectivities at 532 nm during decaying shock compression. The data show up to 40% (or higher) reflectivity, corresponding to notable electrical conductivities, in response to high pressures and temperatures. Furthermore, band-gap closure, dependent on density, can be examined from the reflectivity data. Ionic salts are simple model systems amenable to first-principles theory and serve as analog materials for predicting whether specific chemical constituents can reside in the rocky mantles or metallic cores of planets. A key objective is to disentangle the complementary roles of temperature and compression in transforming ionic into metallic bonding. Furthermore, at high pressures CsI becomes analogous to Xe: they are isoelectronic and follow matching equations of state. Therefore, studies on CsI could inform understanding of noble-gas geochemistry at conditions deep inside planets.

  20. 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.

  1. 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

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry

    2015-06-01

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

  5. Non-contact ultrasonic acquisition of femtosecond laser-driven ablative Mbar-level shock waves on Ti alloy surface

    NASA Astrophysics Data System (ADS)

    Ageev, E. I.; Kudryashov, S. I.; Nikonorov, N. V.; Nuryev, R. K.; Petrov, A. A.; Samokhvalov, A. A.; Veiko, V. P.

    2016-02-01

    Mbar-level ablative plume pressures, produced by single-shot femtosecond laser ablation of a dry Ti alloy surface and driving shock waves in air and in the solid target, were characterized using non-contact broad-band ultrasonic measurements. X-ray diffraction measurements reveal the resulting shock-wave induced sub-GPa residual compressive stresses over multi-micrometer depths inside the target, indicating GPa-level residual compressive stresses on its surface.

  6. 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.

  7. 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.

  8. Weak compressibility of surface wave turbulence

    NASA Astrophysics Data System (ADS)

    Vucelja, Marija; Fouxon, Itzhak; Falkovich, Gregory

    2010-11-01

    Clustering of matter on the surface of lakes and pools and of oil slicks and seaweed on the sea surface is well-known empirically but there is no theory that describes it. Since surface flows are always compressible, such a theory should be based on the description of the development of density of inhomogeneities in a compressible flow. We studied the growth of small-scale inhomogeneities in the density of particles floating in weakly nonlinear small-amplitude surface waves. Despite the small amplitude, the accumulated effect of the long-time evolution may produce a strongly inhomogeneous distribution of the floaters: density fluctuations grow exponentially with a small but finite exponent. We have shown that the exponent is of sixth or higher order in wave amplitude. As a result, the inhomogeneities do not form within typical time scales of the natural environment. Thus the turbulence of surface waves is weakly compressible and alone it cannot be a realistic mechanism of the clustering of matter on liquid surfaces. However if besides waves there are also currents, the interplay of waves with currents, might be in some cases responsible for the patchiness of the floaters.

  9. Whistler waves observed upstream from collisionless shocks

    NASA Technical Reports Server (NTRS)

    Fairfield, D. H.

    1974-01-01

    Waves in the frequency range 0.5-4. Hz have been studied in the region upstream of the earth's bow shock with data from the flux-gate magnetic field experiment on Imp 6. Such waves are invariably detected adjacent to the shock, persisting upstream for intervals often less than a minute but occasionally of the order of many hours. Analysis of 150 examples of these waves during a 3-month interval indicates that propagation directions generally make angles of between 20 and 40 deg 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. The left-handed waves generally have lower frequencies than the right-handed waves, and the left-handed frequencies never exceed 2.5 Hz. The measured sense of polarization is found to depend on the propagation direction (or alternatively, the field direction) relative to the solar wind direction.

  10. 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.

  11. Enhanced densification under shock compression in porous silicon

    DOE PAGESBeta

    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

  12. 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.

  13. 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.

  14. Enhanced densification under shock compression in porous silicon

    NASA Astrophysics Data System (ADS)

    Lane, J. Matthew D.; Thompson, Aidan P.; Vogler, Tracy J.

    2014-10-01

    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. We demonstrate a molecular mechanism that drives this behavior. We also present evidence from atomistic simulation that silicon belongs to this anomalous class of materials. Atomistic simulations indicate that local shear strain in the neighborhood of collapsing pores nucleates 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.

  15. A multi-scale approach to molecular dynamics simulations of shock waves

    SciTech Connect

    Reed, E J; Fried, L E; Manaa, M R; Joannopoulos, J D

    2004-09-03

    Study of the propagation of shock waves in condensed matter has led to new discoveries ranging from new metastable states of carbon [1] to the metallic conductivity of hydrogen in Jupiter, [2] but progress in understanding the microscopic details of shocked materials has been extremely difficult. Complications can include the unexpected formation of metastable states of matter that determine the structure, instabilities, and time-evolution of the shock wave. [1,3] The formation of these metastable states can depend on the time-dependent thermodynamic pathway that the material follows behind the shock front. Furthermore, the states of matter observed in the shock wave can depend on the timescale on which observation is made. [4,1] Significant progress in understanding these microscopic details has been made through molecular dynamics simulations using the popular non-equilibrium molecular dynamics (NEMD) approach to atomistic simulation of shock compression. [5] The NEMD method involves creating a shock at one edge of a large system by assigning some atoms at the edge a fixed velocity. The shock propagates across the computational cell to the opposite side. The computational work required by NEMD scales at least quadratically in the evolution time because larger systems are needed for longer simulations to prevent the shock wave from reflecting from the edge of the computational cell and propagating back into the cell. When quantum mechanical methods with poor scaling of computational effort with system size are employed, this approach to shock simulations rapidly becomes impossible.

  16. 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.

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

    DOE PAGESBeta

    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 scalesmore » . 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 .« less

  18. 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 .

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

    NASA Astrophysics Data System (ADS)

    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.

  20. 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.

  1. 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.

  2. Wave energy devices with compressible volumes

    PubMed Central

    Kurniawan, Adi; Greaves, Deborah; Chaplin, John

    2014-01-01

    We present an analysis of wave energy devices with air-filled compressible submerged volumes, where variability of volume is achieved by means of a horizontal surface free to move up and down relative to the body. An analysis of bodies without power take-off (PTO) systems is first presented to demonstrate the positive effects a compressible volume could have on the body response. Subsequently, two compressible device variations are analysed. In the first variation, the compressible volume is connected to a fixed volume via an air turbine for PTO. In the second variation, a water column separates the compressible volume from another volume, which is fitted with an air turbine open to the atmosphere. Both floating and bottom-fixed, axisymmetric, configurations are considered, and linear analysis is employed throughout. Advantages and disadvantages of each device are examined in detail. Some configurations with displaced volumes less than 2000 m3 and with constant turbine coefficients are shown to be capable of achieving 80% of the theoretical maximum absorbed power over a wave period range of about 4 s. PMID:25484609

  3. 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.

  4. 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.

  5. Investigating Metallization in Shock-Compressed Alkali Halides

    NASA Astrophysics Data System (ADS)

    Diamond, M. R.; Ali, S. J.; Eggert, J.; Jeanloz, R.; Collins, G. W.; McWilliams, R. S.

    2014-12-01

    Laser-shock compression on four alkali halides has been used to probe the transition from insulating to metallic states, a high-pressure transition in chemical bonding that has fundamental implications for planetary formation and structure. Collectively, pressures up to 450 GPa were explored across a total of fourteen single-crystal samples of CsI, CsBr, KBr and NaCl. Velocity interferometry (VISAR) was used to record shock velocities and reflectivities at 532 nm during decaying shock compression. The data show up to three-fold increases in density as well as significant increases in optical reflectivity in response to high pressures and temperatures. Using a Drude model to estimate conductivities from the measured reflectivities, we investigate the onset of metallic conductivities for each compound. Ionic salts are simple model systems amenable to first-principles theory and serve as analog materials for predicting whether specific chemical constituents can reside in the rocky mantles or metallic cores of planets. A key objective is to disentangle the complementary roles of temperature and compression in transforming ionic into metallic bonding. Furthermore, at high pressures CsI becomes analogous to Xe: they are isoelectronic and follow matching equations of state. Therefore, studies on CsI can inform understanding of noble-gas geochemistry at conditions deep inside planets (e.g., the likelihood of Xe solubility in planetary mantles or cores). Our experiments were conducted using the Janus laser of the Jupiter Laser Facility at Lawrence Livermore National Laboratory.

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

    PubMed

    Davie, C J; Evans, R G

    2013-05-01

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

  7. Advances in ferroelectric polymers for shock compression sensors

    SciTech Connect

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

    1997-10-01

    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% in electric 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.

  8. 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.}

  9. 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.

  10. Optimizing Shock Wave Lithotripsy: A Comprehensive Review

    PubMed Central

    McClain, Paul D; Lange, Jessica N; Assimos, Dean G

    2013-01-01

    Shock wave lithotripsy is a commonly used procedure for eradicating upper urinary tract stones in patients who require treatment. A number of methods have been proposed to improve the results of this procedure, including proper patient selection, modifications in technique, adjunctive therapy to facilitate elimination of fragments, and changes in lithotripter design. This article assesses the utility of these measures through an analysis of contemporary literature. PMID:24082843

  11. Scattering of shock waves in QCD

    SciTech Connect

    Ian Balitsky

    2004-09-01

    The cross section of heavy-ion collisions is represented as a double functional integral with the saddle point being the classical solution of the Yang-Mills equations with boundary conditions/sources in the form of two shock waves corresponding to the two colliding ions. I develop the expansion of this classical solution in powers of the commutator of the Wilson lines describing the colliding particles and calculate the first two terms of the expansion.

  12. 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.

  13. 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.

  14. Gas turbine power plant with supersonic shock compression ramps

    DOEpatents

    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.

  15. Three-dimensional shock-wave/boundary-layer interactions with bleed through a circular hole

    NASA Technical Reports Server (NTRS)

    Rimlinger, M. J.; Shih, T. I.-P.; Chyu, W. J.

    1992-01-01

    Computations were performed to study three-dimensional (3-D), shock-wave/boundary-layer interactions on a flat plate in which fluid in the boundary layer was bled through a circular hole into a plenum to control shock-wave induced separation. Results are presented which show the details of the 3-D flowfield about the bleed hole and how bleed-hole placement relative to shock-wave impingement affect upstream, spanwise, and downstream influence lengths. This study revealed an underlying mechanisms by which bleed holes can affect shock-wave/boundary-layer interactions. This investigation is based on the ensemble-averaged, "full-compressible" Navier-Stokes equations closed by the Baldwin-Lomax turbulence model. Solutions to these equations were obtained by an implicit finite-volume method based on the partially-split, two-factored algorithm of Steger.

  16. 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.

  17. Turbulent magnetized plasmas from ionizing shock waves

    NASA Astrophysics Data System (ADS)

    Liang, Zuohua

    Turbulent argon plasmas produced behind hypersonic shock waves (10 less than M less than 60) are studied in the presence of weak magnetic fields at various strengths between 0 and 600 gauss, parallel and antiparallel to the shock tube's axis. The experiment is performed in a cylindrical arc discharge shock tube of 5 cm diameter and 210 cm overall length. Laser induced fluorescence and an electric probe are used as diagnostics of the ion density. Turbulent fluctuations behind the shock front are observed which persist for a time in the order of 10 msec. Using standard turbulent and chaotic analytical procedures, the influence of the magnetic field on the characterizing parameters is determined under circumstances of changing Mach number and pressure. These parameters include spectral index, correlation time scales, turbulent intensity and chaotic dimensionality. The parameters of turbulence obtained from the two diagnostics are quite consistent. Fluctuation power spectra follow a P approx. f(sup -n) behavior with 1.3 less than n less than 2.8; this agrees with theoretical predictions as well as the results of other investigators. An increasing magnetic field increases the characterizing correlation time, the turbulent intensity, and the chaotic dimension but decreases the small correlation time. Therefore the magnetic field decreases the order (increases the dimensionality) in the turbulent plasma, independent of the direction of the field parallel or antiparallel to the direction of the shock wave. A turbulent velocity-field-coupling model is proposed. A dispersion relation shows that, in the presence of an external magnetic field, varieties of new modes in a turbulent plasma are generated. The model predicts an increasing complexity of the turbulent system with increasing strength of the field and is in very good qualitative agreement with our experiment results.

  18. Turbulent magnetized plasmas from ionizing shock waves

    SciTech Connect

    Liang, Zuohua.

    1992-01-01

    Turbulent argon plasmas produced behind hypersonic shock waves (10 less than M less than 60) are studied in the presence of weak magnetic fields at various strengths between 0 and 600 gauss, parallel and antiparallel to the shock tube's axis. The experiment is performed in a cylindrical arc discharge shock tube of 5 cm diameter and 210 cm overall length. Laser induced fluorescence and an electric probe are used as diagnostics of the ion density. Turbulent fluctuations behind the shock front are observed which persist for a time in the order of 10 msec. Using standard turbulent and chaotic analytical procedures, the influence of the magnetic field on the characterizing parameters is determined under circumstances of changing Mach number and pressure. These parameters include spectral index, correlation time scales, turbulent intensity and chaotic dimensionality. The parameters of turbulence obtained from the two diagnostics are quite consistent. Fluctuation power spectra follow a P approx. f(sup -n) behavior with 1.3 less than n less than 2.8; this agrees with theoretical predictions as well as the results of other investigators. An increasing magnetic field increases the characterizing correlation time, the turbulent intensity, and the chaotic dimension but decreases the small correlation time. Therefore the magnetic field decreases the order (increases the dimensionality) in the turbulent plasma, independent of the direction of the field parallel or antiparallel to the direction of the shock wave. A turbulent velocity-field-coupling model is proposed. A dispersion relation shows that, in the presence of an external magnetic field, varieties of new modes in a turbulent plasma are generated. The model predicts an increasing complexity of the turbulent system with increasing strength of the field and is in very good qualitative agreement with our experiment results.

  19. 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

  20. Tight-Binding Molecular Dynamics Simulations of Shock-Compressed Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Kress, J. D.; Bickham, S. R.; Holian, B. L.; Collins, L. A.

    1999-06-01

    We have used tight-binding molecular dynamics to simulate shock waves in liquid hydocarbons. The equations of motion in supercells containing as many as 1024 methane and 576 benzene molecules (8192 and 17,280 valence electrons, respectively) are integrated using an O(N) electronic structure algorithm(S. Goedecker and L. Columbo, Phys. Rev. Lett. 73), 122 (1994); A.F. Voter, J.D. Kress and R.N. Silver, Phys. Rev. B 53, 12733 (1996) implemented on a massively parallel computer. In the non-equilibrium shock compression simulation, uniaxial contracting periodic boundary conditions were employed, with both ends of an elongated supercell moving inward at a constant (piston) velocity. The velocities of the shock waves created in this manner are compared to gas gun experimentsfootnote W. J. Nellis et al., J. Chem. Phys. 75, 3055 (1981). Analysis of the medium between the piston and shock front indicates that methane is decomposed into molecular hydrogen and carbon residue, while shocked benzene forms a mixture of hydrocarbons and molecular hydrogen. The dynamics of these chemical transformations will be discussed.

  1. 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

  2. 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.

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

    SciTech Connect

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

    2012-12-15

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

  4. A relaxation-projection method for compressible flows. Part II: Artificial heat exchanges for multiphase shocks

    SciTech Connect

    Petitpas, Fabien; Franquet, Erwin; Saurel, Richard . E-mail: Richard.Saurel@polytech.univ-mrs.fr; Le Metayer, Olivier

    2007-08-10

    The relaxation-projection method developed in Saurel et al. [R. Saurel, E. Franquet, E. Daniel, O. Le Metayer, A relaxation-projection method for compressible flows. Part I: The numerical equation of state for the Euler equations, J. Comput. Phys. (2007) 822-845] is extended to the non-conservative hyperbolic multiphase flow model of Kapila et al. [A.K. Kapila, Menikoff, J.B. Bdzil, S.F. Son, D.S. Stewart, Two-phase modeling of deflagration to detonation transition in granular materials: reduced equations, Physics of Fluids 13(10) (2001) 3002-3024]. This model has the ability to treat multi-temperatures mixtures evolving with a single pressure and velocity and is particularly interesting for the computation of interface problems with compressible materials as well as wave propagation in heterogeneous mixtures. The non-conservative character of this model poses however computational challenges in the presence of shocks. The first issue is related to the Riemann problem resolution that necessitates shock jump conditions. Thanks to the Rankine-Hugoniot relations proposed and validated in Saurel et al. [R. Saurel, O. Le Metayer, J. Massoni, S. Gavrilyuk, Shock jump conditions for multiphase mixtures with stiff mechanical relaxation, Shock Waves 16 (3) (2007) 209-232] exact and approximate 2-shocks Riemann solvers are derived. However, the Riemann solver is only a part of a numerical scheme and non-conservative variables pose extra difficulties for the projection or cell average of the solution. It is shown that conventional Godunov schemes are unable to converge to the exact solution for strong multiphase shocks. This is due to the incorrect partition of the energies or entropies in the cell averaged mixture. To circumvent this difficulty a specific Lagrangian scheme is developed. The correct partition of the energies is achieved by using an artificial heat exchange in the shock layer. With the help of an asymptotic analysis this heat exchange takes a similar form as

  5. 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.

  6. 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.

  7. Fully dense Sm2Fe17Nx permanent magnets prepared by shock compression

    NASA Astrophysics Data System (ADS)

    Mashimo, Tsutomu; Tashiro, Suguru; Hirosawa, Satoshi; Makita, Ken

    1996-07-01

    Fully dense Sm2Fe17Nx bulk bodies with porosities less than 5% were prepared by shock compression in a certain low-pressure region, using the magnetically aligned powder pellets with an initial porosity of 46%-52% and without binder. Below a driving shock pressure (single shock wave using a copper standard capsule) of about 10 GPa, the recovered specimens did not consolidate well, and above about 20 GPa they began to decompose to α-Fe and Sm nitride. The consolidated state and porosity depended on the driving shock pressure, the thickness and porosity of the starting powder pellet, and the thickness of the impact plate. It was found that the shock consolidated bulk bodies had a Curie temperature of approximately 475 °C, and that the magnetic properties were sensitive to shock pressure, porosity, alignment, etc. The largest values of coercivity and maximum energy product of the recovered bulk specimens prepared in this study were 7.1 kOe and 16.8 MGOe, respectively.

  8. Amorphization and nanocrystallization of silcon under shock compression

    DOE PAGESBeta

    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

  9. 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.

  10. 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.

  11. Nonequilibrium ionization phenomena behind shock waves

    SciTech Connect

    Panesi, Marco; Magin, Thierry; Huo, Winifred

    2011-05-20

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

  12. Particle Acceleration in SN1006 Shock Waves

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    This grant is for the analysis of FUSE observations of particle acceleration in supernova remnant SN1006 shock waves. We have performed quick look analysis of the data, but because the source is faint and because the O VI emission lines on SN1006 are extremely broad, extreme care is needed for background subtraction and profile fitting. Moreover, the bulk of the analysis in will consist of model calculations. The Ly beta and O VI lines are clearly detected at the position in the NW filament of SN1006, but not in the NE position where non-thermal X-rays are strong. The lack of O VI emission in the NE places an upper limit on the pre-shock density there.

  13. Nonplanar electrostatic shock waves in dense plasmas

    SciTech Connect

    Masood, W.; Rizvi, H.

    2010-02-15

    Two-dimensional quantum ion acoustic shock waves (QIASWs) are studied in an unmagnetized plasma consisting of electrons and ions. In this regard, a nonplanar quantum Kadomtsev-Petviashvili-Burgers (QKPB) equation is derived using the small amplitude perturbation expansion method. Using the tangent hyperbolic method, an analytical solution of the planar QKPB equation is obtained and subsequently used as the initial profile to numerically solve the nonplanar QKPB equation. It is observed that the increasing number density (and correspondingly the quantum Bohm potential) and kinematic viscosity affect the propagation characteristics of the QIASW. The temporal evolution of the nonplanar QIASW is investigated both in Cartesian and polar planes and the results are discussed from the numerical stand point. The results of the present study may be applicable in the study of propagation of small amplitude localized electrostatic shock structures in dense astrophysical environments.

  14. 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.

  15. 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.

  16. X-ray Thomson scattering measurements from shock-compressed deuterium

    NASA Astrophysics Data System (ADS)

    Davis, P.; Doeppner, T.; Rygg, J. R.; Fortmann, C.; Unites, W.; Salmonson, J.; Collins, G. W.; Landen, O. L.; Falcone, R. W.; Glenzer, S. H.

    2012-05-01

    X-ray Thomson scattering has recently been shown to be an effective method of diagnosing a variety of high energy density plasma conditions. We apply this powerful technique to the widely studied problem of shock-compressed liquid deuterium. The behavior of deuterium under extreme conditions has received considerable attention due to its central role in models of giant planets and the importance of the high-pressure insulator-metal transition. We have used spectrally resolved x-ray scattering from electron-plasma waves to perform microscopic observations of ionization during compression. In these experiments, a single shock was launched in cryogenic deuterium reaching compressions of 3x. The 2 keV Ly-α line in silicon was used as an x-ray source in a forward scattering geometry. In addition to elastic scattering from tightly bound electrons, this low probe energy accessed the collective plasmon oscillations of delocalized electrons. Inelastic scattering from the plasmons allowed accurate measurements of the free electron density through the spectral position of the resonance and provided an estimate of the temperature through its ratio with the elastic feature. Combined with velocity interferometry from the reflective shock front, this lead to a direct determination of the ionization state. We compare the measured ionization conditions with computational models. Additionally, we discuss the possibility of using this technique to determine electrical conductivity and to directly observe pressure-induced molecular dissociation along the Hugoniot.

  17. X-ray Thomson scattering measurements from shock-compressed deuterium

    SciTech Connect

    Davis, P.; Doeppner, T.; Rygg, J. R.; Fortmann, C.; Unites, W.; Salmonson, J.; Collins, G. W.; Landen, O. L.; Falcone, R. W.; Glenzer, S. H.

    2012-05-25

    X-ray Thomson scattering has recently been shown to be an effective method of diagnosing a variety of high energy density plasma conditions. We apply this powerful technique to the widely studied problem of shock-compressed liquid deuterium. The behavior of deuterium under extreme conditions has received considerable attention due to its central role in models of giant planets and the importance of the high-pressure insulator-metal transition. We have used spectrally resolved x-ray scattering from electron-plasma waves to perform microscopic observations of ionization during compression. In these experiments, a single shock was launched in cryogenic deuterium reaching compressions of 3x. The 2 keV Ly-{alpha} line in silicon was used as an x-ray source in a forward scattering geometry. In addition to elastic scattering from tightly bound electrons, this low probe energy accessed the collective plasmon oscillations of delocalized electrons. Inelastic scattering from the plasmons allowed accurate measurements of the free electron density through the spectral position of the resonance and provided an estimate of the temperature through its ratio with the elastic feature. Combined with velocity interferometry from the reflective shock front, this lead to a direct determination of the ionization state. We compare the measured ionization conditions with computational models. Additionally, we discuss the possibility of using this technique to determine electrical conductivity and to directly observe pressure-induced molecular dissociation along the Hugoniot.

  18. X-ray Radiography and Scattering Diagnosis of Dense Shock-Compressed Matter

    NASA Astrophysics Data System (ADS)

    Lepape, Sebastien

    2009-11-01

    Spectrally resolved x-ray Thomson scattering is an established technique that allows characterizing Fermi degenerate dense plasmas accessible in laser shocked-compressed foil experiments. It has been used in a variety of experiments that, besides measuring plasma density and temperature, served as critical test for models that calculate important plasma parameters like structure factors, bound-free contributions, and ionization energy lowering in warm dense matter. Experiments realized at the TITAN facility at Lawrence Livermore National Laboratory apply ultra-short pulse laser produced K- x rays to characterize plasmas at pressures above 1.5 Mbar that are produced with an energetic nanosecond laser. High energy x-rays produced by the short pulse laser allow probing compressed matter with a high temporal resolution (about 10 ps). From collective and non-collective scattering spectra mass density of the compressed Boron is inferred. X-ray radiography has been used as an independent way to characterize the mass density of matter for identical drive conditions. Here, we use K- X rays in a point projection scheme to probe the shock wave. Densities ranging from 3 to 4 g/cc have been measured, in excellent agreement with the x-ray Thomson scattering data. These radiography data combined with accurate measurement of the Plasmon dispersion in shocked Boron help improving the accuracy of the collision model as well as structure factor calculation.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  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. Experimental Study of Shock-Induced Compression and Vortex Generation in the Shock-Bubble Interaction

    NASA Astrophysics Data System (ADS)

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

    2006-11-01

    Results are presented from experiments studying the interaction of a planar shock wave of strength 1.4 shock tube with a square internal cross-section, 0.254 m on a side, equipped with a pneumatically driven retracting bubble injector. The absence of a bubble holder during shock wave passage allows for a cleaner initial condition while avoiding complications associated with holder/shock interaction. As the planar shock passes over the bubble, the intense vortical and nonlinear acoustic phenomena characterized initially by Haas and Sturtevant (J. Fluid. Mech., 1987) are observed, including vortex ring formation, intense mixing, and growth of turbulence-like features. Flow visualizations are obtained using planar laser diagnostics rather than integral measures. The origin and growth of distinctive counter-rotating secondary vortical features are observed in high Mach number experiments. A number of features of the shock bubble interaction are investigated and parameterized with the incident M and the initial density difference. These include the axial and lateral extents of the bubble, the translational velocity of the bubble and associated vortex rings, and the circulation of the vortex rings.

  6. 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.

  7. 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.

  8. 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.

  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

    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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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. PMID:23411473

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Shock-wave boundary layer interactions

    NASA Technical Reports Server (NTRS)

    Delery, J.; Marvin, J. G.; Reshotko, E.

    1986-01-01

    Presented is a comprehensive, up-to-date review of the shock-wave boundary-layer interaction problem. A detailed physical description of the phenomena for transonic and supersonic speed regimes is given based on experimental observations, correlations, and theoretical concepts. Approaches for solving the problem are then reviewed in depth. Specifically, these include: global methods developed to predict sudden changes in boundary-layer properties; integral or finite-difference methods developed to predict the continuous evolution of a boundary-layer encountering a pressure field induced by a shock wave; coupling methods to predict entire flow fields; analytical methods such as multi-deck techniques; and finite-difference methods for solving the time-dependent Reynolds-averaged Navier-Stokes equations used to predict the development of entire flow fields. Examples are presented to illustrate the status of the various methods and some discussion is devoted to delineating their advantages and shortcomings. Reference citations for the wide variety of subject material are provided for readers interested in further study.

  3. 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.

  4. On the inception lengths of swept shock-wave/turbulent boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Settles, G. S.

    1986-01-01

    Experimental data are shown for the inception lengths of swept compression corner-generated and fin-generated shock/boundary layer interactions at Mach 2.95. These results are found to correlate on the basis of three different flow regimes. The inception lengths of these flows are dominated by a singularity at the cylindrical/conical boundary for swept corners and by an elongation due to shock wave sweepback for fin interactions. Similarity rules for both Re(delta)and shock generator geometry effects on inception lengths are demonstrated.

  5. Shock effects in quartz: Compression versus shear deformation — An example from the Rochechouart impact structure, France

    NASA Astrophysics Data System (ADS)

    Trepmann, C. A.

    2008-03-01

    Different quartz microstructures from Rochechouart impact breccias, indicative of shock-induced compression and shear deformation are compiled, to obtain information on the mean stress and the deviatoric components of the shock wave-associated stress. Annealed rhombohedral planar deformation features (PDFs) are widespread in quartz from Rochechouart impact breccias, as analysed by optical microscopy, scanning electron and transmission electron microscopy. Shocked quartz can show mosaicism with domains of < 200 nm in diameter that are misoriented to each other. This is interpreted as the result of post-shock annealing of a high density of rhombohedral PDFs crosscutting each other. Pockets of newly crystallised quartz aggregates, interpreted as annealed diaplectic glass, are surrounded by optically almost isotropic quartz and occur in intensely shocked quartz. These areas are proposed to represent gradually increasing shock intensities from the host quartz grain to the newly crystallised quartz aggregate due to local pressure and temperature variations on the mm-scale. These microstructures indicate compression at high shock pressures (20-35 GPa) and they show no evidence of shear deformation at high differential stress. Annealing of these microstructures probably took place shortly after shock when post-shock temperatures were still high. Quartz microstructures in the Rochechouart impact breccias that record shock-induced shear deformation are mechanical Brazil twins and planar fractures that are supposed to represent microfaults. These shock effects indicate high differential stress on the order of a few GPa. Quartz that contains Brazil twins and planar fractures shows no or few rhombohedral PDFs, indicating relatively low shock pressures (< 15 GPa). In general, shock effects indicating high differential stress do not occur together with those indicative of high shock pressure. These findings reveal that high shock pressures (> 20 GPa) are apparently not

  6. 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.

  7. Advances in CFD prediction of shock wave turbulent boundary layer interactions

    NASA Astrophysics Data System (ADS)

    Knight, Doyle; Yan, Hong; Panaras, Argyris G.; Zheltovodov, Alexander

    2003-04-01

    The paper presents a summary of recent computational fluid dynamics (CFD) simulations of shock wave turbulent boundary layer interactions. This survey was prepared as part of the activity of NATO RTO Working Group 10 which was established in December 1998, and considers results obtained subsequent to the previous survey paper on the same topic by Knight and Degrez (“Shock Wave Boundary Layer Interactions in High Mach Number Flows-A Critical Survey of Current CFD Prediction Capabilities”, AGARD Advisory Report AR-319, Volume II, December 1998). Five configurations are considered: 2-D compression corner, 2-D shock impingement, 2-D expansion-compression corner, 3-D single fin and 3-D double fin. Recent direct numerical simulations (DNS), large eddy simulations (LES) and Reynolds-averaged Navier-Stokes (RANS) simulations are compared with experiment. The capabilities and limitations are described, and future research needs identified.

  8. 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.

  9. 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.

  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. Waves in low-beta plasmas - Slow shocks

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    Results from wave theory and numerical simulation of the nonlinear MHD equations are used to study the response of a conducting fluid containing an embedded magnetic field with beta less than 1 to the sudden injection of material along the field lines. It is shown that the injection produces slow shocks with configurations which are concave toward the ejecta driver. Fast-mode waves which have not steepened into the shock precede the slow shock and alter the ambient medium. When beta equals 0.1, the fast mode becomes a transverse wave for parallel propagation, while the slow wave approaches a longitudinal, or sound, wave.

  12. 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.

  13. Shock wave propagation in semi-crystalline polyethylene: An atomic-scale investigation

    NASA Astrophysics Data System (ADS)

    Elder, Robert M.; O'Connor, Thomas C.; Yeh, In-Chul; Chantawansri, Tanya L.; Sirk, Timothy W.; Robbins, Mark O.; Andzelm, Jan W.

    Highly oriented polyethylene (PE) fibers are used in protection applications, therefore elucidation of their response under high strain-rate impact events is vital. Although PE fibers can have high crystallinity (>95%), they also contain defects such as amorphous domains. Using molecular dynamics simulations, we investigate shock propagation through crystalline, amorphous, and semi-crystalline PE. We generate compressive shock waves of varying strength, quantify their dynamics, and characterize their effect on material properties at the atomic scale. In the semi-crystalline PE model, the differing density and molecular order of amorphous PE and crystalline PE result in differing shock impedances, which causes reflection and refraction of shock waves at interfaces between the phases. We quantify the properties (e.g. pressure, velocity) of the reflected and refracted waves, which differ from those of the incident wave, and compare with results from impedance matching. We also examine the reflection, absorption, and transmission of energy at the crystalline-amorphous interface. Depending on shock strength, amorphous defects can dissipate shock energy, which attenuates the shock and leads to effects such as localized heating.

  14. Predicting the shock compression response of heterogeneous powder mixtures

    NASA Astrophysics Data System (ADS)

    Fredenburg, D. A.; Thadhani, N. N.

    2013-06-01

    A model framework for predicting the dynamic shock-compression response of heterogeneous powder mixtures using readily obtained measurements from quasi-static tests is presented. Low-strain-rate compression data are first analyzed to determine the region of the bulk response over which particle rearrangement does not contribute to compaction. This region is then fit to determine the densification modulus of the mixture, σD, an newly defined parameter describing the resistance of the mixture to yielding. The measured densification modulus, reflective of the diverse yielding phenomena that occur at the meso-scale, is implemented into a rate-independent formulation of the P-α model, which is combined with an isobaric equation of state to predict the low and high stress dynamic compression response of heterogeneous powder mixtures. The framework is applied to two metal + metal-oxide (thermite) powder mixtures, and good agreement between the model and experiment is obtained for all mixtures at stresses near and above those required to reach full density. At lower stresses, rate-dependencies of the constituents, and specifically those of the matrix constituent, determine the ability of the model to predict the measured response in the incomplete compaction regime.

  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. Steady state risetimes of shock waves in the atmosphere

    NASA Technical Reports Server (NTRS)

    Raspet, Richard; Bass, Henry; Yao, Lixin; Wu, Wenliang

    1992-01-01

    A square wave shape is used in the Pestorius algorithm to calculate the risetime of a step shock in the atmosphere. These results agree closely with steady shock calculations. The healing distance of perturbed shocks due to finite wave effects is then investigated for quasi-steady shocks. Perturbed 100 Pa shocks require on the order of 1.0 km travel distance to return to within 10 percent of their steady shock risetime. For 30 Pa shocks, the minimum recovery distance increases to 3.0 km. It is unlikely that finite wave effects can remove the longer risetimes and irregular features introduced into the sonic boom by turbulent scattering in the planetary boundary layer.

  17. Interaction between shock wave and single inertial bubbles near an elastic boundary

    NASA Astrophysics Data System (ADS)

    Sankin, G. N.; Zhong, P.

    2006-10-01

    The interaction of laser-generated single inertial bubbles (collapse time=121μs ) near a silicon rubber membrane with a shock wave ( 55MPa in peak pressure and 1.7μs in compressive pulse duration) is investigated. The interaction leads to directional, forced asymmetric collapse of the bubble with microjet formation toward the surface. Maximum jet penetration into the membrane is produced during the bubble collapse phase with optimal shock wave arrival time and stand-off distance. Such interaction may provide a unique acoustic means for in vivo microinjection, applicable to targeted delivery of macromolecules and gene vectors to biological tissues.

  18. Interaction between shock wave and single inertial bubbles near an elastic boundary.

    PubMed

    Sankin, G N; Zhong, P

    2006-10-01

    The interaction of laser-generated single inertial bubbles (collapse time = 121 mus) near a silicon rubber membrane with a shock wave (55 MPa in peak pressure and 1.7 mus in compressive pulse duration) is investigated. The interaction leads to directional, forced asymmetric collapse of the bubble with microjet formation toward the surface. Maximum jet penetration into the membrane is produced during the bubble collapse phase with optimal shock wave arrival time and stand-off distance. Such interaction may provide a unique acoustic means for in vivo microinjection, applicable to targeted delivery of macromolecules and gene vectors to biological tissues. PMID:17155170

  19. 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.

  20. Characteristic of ion acoustic shock waves in a dissipative quantum pair plasma with dust particulates

    NASA Astrophysics Data System (ADS)

    Rouhani, M. R.; Mohammadi, Z.; Akbarian, A.

    2014-01-01

    The behavior of quantum dust ion-acoustic (QDIA) shocks in a plasma including inertialess quantum electrons and positrons, classical cold ions and stationary negative dust grains are studied, using a quantum hydrodynamic model (QHD). The effect of dissipation due to the viscosity of ions is taken into account. The propagation of small but finite amplitude QDIA shocks is governed by the Kortoweg-de Vries-Burgers (KdVB) equation. The existence regions of oscillatory and monotonic shocks will depend on the quantum diffraction parameter ( H) and dust density ( d) as well as dissipation parameter ( η 0). The effect of plasma parameters ( d, H, η 0), on these structures is investigated. Results indicate that the thickness and height of monotonic shocks; oscillation amplitude of the oscillatory shock wave and it's wavelength effectively are affected by these parameters. Additionally, the possibility of propagation of both compressive and rarefactive shocks is investigated. It is found that depending on some critical value of dust density ( d c ), which is a function of H, compressive and rarefactive shock waves can't propagate in model plasma. The present theory is applicable to analyze the formation of nonlinear structures at quantum scales in dense astrophysical objects.

  1. 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.

  2. 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

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

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry W.

    2001-06-01

    To provide broader scientific recognition and to advance the science of shock-compressed condensed matter, a group of APS members worked within the Society to make this technical field an active part of APS. Individual papers were given at APS meetings starting in the 1950’s and then later whole sessions were organized starting at the 1967 Pasadena meeting. Topical conferences began in 1979 in Pullman, WA where George Duvall and Dennis Hayes were co-chairs. Most all early topical conferences were sanctioned by the APS while those held after 1985 were official APS meetings. In 1984, after consulting with a number of people in the shock wave field, Robert Graham circulated a petition to form an APS topical group. He obtained signatures from a balanced cross-section of the community. William Havens, the executive secretary of APS, informed Robert Graham by letter on November 28, 1984 that the APS Council had officially accepted the formation of this topical group at its October 28, 1984 meeting. The first election occurred July 23, 1985 where Robert Graham was elected chairman, William Nellis vice-chairman, and Jerry Forbes secretary/treasurer. The topical group remains viable today by holding a topical conference in odd numbered years and shock wave sessions at APS general meetings in even numbered years A major benefit of being an official unit of APS is the allotment of APS fellows every year. The APS shock compression award established in 1987, has also provided broad recognition of many major scientific accomplishments in this field.

  4. Transonic Shocks for the Full Compressible Euler System in a General Two-Dimensional De Laval Nozzle

    NASA Astrophysics Data System (ADS)

    Li, Jun; Xin, Zhouping; Yin, Huicheng

    2013-02-01

    In this paper, we study the transonic shock problem for the full compressible Euler system in a general two-dimensional de Laval nozzle as proposed in Courant and Friedrichs (Supersonic flow and shock waves, Interscience, New York, 1948): given the appropriately large exit pressure p e( x), if the upstream flow is still supersonic behind the throat of the nozzle, then at a certain place in the diverging part of the nozzle, a shock front intervenes and the gas is compressed and slowed down to subsonic speed so that the position and the strength of the shock front are automatically adjusted such that the end pressure at the exit becomes p e( x). We solve this problem completely for a general class of de Laval nozzles whose divergent parts are small and arbitrary perturbations of divergent angular domains for the full steady compressible Euler system. The problem can be reduced to solve a nonlinear free boundary value problem for a mixed hyperbolic-elliptic system. One of the key ingredients in the analysis is to solve a nonlinear free boundary value problem in a weighted Hölder space with low regularities for a second order quasilinear elliptic equation with a free parameter (the position of the shock curve at one wall of the nozzle) and non-local terms involving the trace on the shock of the first order derivatives of the unknown function.

  5. 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.

  6. Tandem shock wave cavitation enhancement for extracorporeal lithotripsy.

    PubMed

    Loske, Achim M; Prieto, Fernando E; Fernandez, Francisco; van Cauwelaert, Javier

    2002-11-21

    Extracorporeal shock wave lithotripsy (ESWL) has been successful for more than twenty years in treating patients with kidney stones. Hundreds of underwater shock waves are generated outside the patient's body and focused on the kidney stone. Stones fracture mainly due to spalling, cavitation and layer separation. Cavitation bubbles are produced in the vicinity of the stone by the tensile phase of each shock wave. Bubbles expand, stabilize and finally collapse violently, creating stone-damaging secondary shock waves and microjets. Bubble collapse can be intensified by sending a second shock wave a few hundred microseconds after the first. A novel method of generating two piezoelectrically generated shock waves with an adjustable time delay between 50 and 950 micros is described and tested. The objective is to enhance cavitation-induced damage to kidney stones during ESWL in order to reduce treatment time. In vitro kidney stone model fragmentation efficiency and pressure measurements were compared with those for a standard ESWL system. Results indicate that fragmentation efficiency was significantly enhanced at a shock wave delay of about 400 and 250 micros using rectangular and spherical stone phantoms, respectively. The system presented here could be installed in clinical devices at relatively low cost, without the need for a second shock wave generator. PMID:12476975

  7. 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.

  8. Plasma Shock Wave Modification Experiments in a Temperature Compensated Shock Tube

    NASA Technical Reports Server (NTRS)

    Vine, Frances J.; Mankowski, John J.; Saeks, Richard E.; Chow, Alan S.

    2003-01-01

    A number of researchers have observed that the intensity of a shock wave is reduced when it passes through a weakly ionized plasma. While there is little doubt that the intensity of a shock is reduced when it propagates through a weakly ionized plasma, the major question associated with the research is whether the reduction in shock wave intensity is due to the plasma or the concomitant heating of the flow by the plasma generator. The goal of this paper is to describe a temperature compensated experiment in a "large" diameter shock tube with an external heating source, used to control the temperature in the shock tube independently of the plasma density.

  9. 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.

  10. 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.

  11. Laser control of filament-induced shock wave in water

    NASA Astrophysics Data System (ADS)

    Potemkin, F. V.; Mareev, E. I.; Podshivalov, A. A.; Gordienko, V. M.

    2014-09-01

    We discovered that tight focusing of Cr:forsterite femtosecond laser radiation in water provides the unique opportunity of long filament generation. The filament becomes a source of numerous spherical shock waves whose radius tends to saturate with the increase of energy. These overlapping waves create a contrast cylindrical shock wave. The laser-induced shock wave parameters such as shape, amplitude and speed can be effectively controlled by varying energy and focusing geometry of the femtosecond pulse. Aberrations added to the optical scheme lead to multiple dotted plasma sources for shock wave formation, spaced along the optical axis. Increasing the laser energy launches filaments at each dot that enhance the length of the entire filament and as a result, the shock impact on the material.

  12. 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.

  13. 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

  14. Spectroscopy During Laser Induced Shock Wave Lithotripsy

    NASA Astrophysics Data System (ADS)

    Engelhardt, R.; Meyer, W.; Hering, P.

    1988-06-01

    In the course of laser induced shock wave lithotripsy (LISL) by means of a flashlamp pumped dye laser a plasma is formed on the stone's surface. Spectral analysis of the plasma flash leads to chemical stone analysis during the procedure. A time resolved integral analysis of scattered and laser induced fluorescence light makes stone detection possible and avoids tissue damage. We used a 200 μm fiber to transmit a 2 μs, 50 mJ pulse to the stone's surface and a second 200 μ fiber for analysis. This transmission system is small and flexible enough for controlled endoscopic use in the treatment of human ureter or common bile duct stones. Under these conditions the stone selective effect of lasertripsy leads only to minor tissue injury.

  15. Modelling Shock Waves in Composite Materials

    NASA Astrophysics Data System (ADS)

    Vignjevic, Rade; Campbell, J. C.; Bourne, N.; Matic, Ognjen; Djordjevic, Nenad

    2007-12-01

    Composite materials have been of significant interest due to widespread application of anisotropic materials in aerospace and civil engineering problems. For example, composite materials are one of the important types of materials in the construction of modern aircraft due to their mechanical properties. The strain rate dependent mechanical behaviour of composite materials is important for applications involving impact and dynamic loading. Therefore, we are interested in understanding the composite material mechanical properties and behaviour for loading rates between quasistatic and 1×108 s-1. This paper investigates modelling of shock wave propagation in orthotropic materials in general and a specific type of CFC composite material. The determination of the equation of state and its coupling with the rest of the constitutive model for these materials is presented and discussed along with validation from three dimensional impact tests.

  16. 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

  17. Large amplitude compression and shear wave propagation in an elastomer

    NASA Astrophysics Data System (ADS)

    Gupta, Y. M.; Murri, W. J.; Henley, D.

    1982-04-01

    Experimental techniques have been developed to measure the high strain-rate compression and shear response of Solithane 113. Compression and shear wave profiles have been measured in specimens compressed to 20% (compressive stresses ˜1.2 GPa). The compressive profiles are nearly steady and the compressive stress-strain response is typical of a compliant material. The shear wave profiles are dispersive and show attenuation with propagation. Analyses of these wave profiles will be presented. Shear moduli vary from 0.35 GPa to 0.8 GPa for the compression range examined to date. These values are within a factor of two of the static shear moduli in the glassy state. The data described here have been used to calculate the high strain rate compressive and shear stress-strain curves for Solithane 113.

  18. 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.

  19. Pump probe based Raman spectroscopic studies of PTFE under laser driven shock compression

    NASA Astrophysics Data System (ADS)

    Rastogi, Vinay; Rao, Usha; Chaurasia, S.; Mishra, A. K.; Poswal, H. K.; Deo, M. N.; Sharma, S. M.

    2016-05-01

    High pressure spontaneous Raman spectroscopic studies of poly tetra fluro ethylene (PTFE) have been carried out under laser driven shock compression in confinement geometry target. The Raman modes under shock compression as a function of pressure were measured and compared with the corresponding Raman modes in static pressure experiments. Our results indicate that PTFE undergoes transition to phase III across this pressure.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Shock Compression of Cryogenic Noble Gas Mixtures: Xenon - Krypton

    NASA Astrophysics Data System (ADS)

    Root, Seth; Magyar, Rudolph; Lemke, Raymond; Mattsson, Thomas

    2013-06-01

    In past work, we have examined the multi-Mbar response of cryogenically cooled liquid xenon and liquid krypton measuring their Hugoniots to 8 Mbar. These results were utilized in the development of new EOS models for Xe and Kr to use in high energy density physics applications. The previous work demonstrated the usefulness of integrating high accuracy shock compression experiments with DFT to generate the basis for equation of state (EOS) models. In many physics applications, such as Z-pinch experiments, gas mixtures are used instead. However, we do not have reliable experimental data on these mixtures to provide informed decisions about the EOS models or mixture rules. To improve our understanding of mixtures at extreme conditions, we performed dynamic compression experiments using Sandia's Z - facility on a 70/30 molar ratio Kr/Xe cryogenically cooled liquid mixture. We measured the Hugoniot state and reshock state of the liquid mixture to several Mbar. The experimental data validated the DFT simulations for identical molar ratio mixtures. The combined experimental and DFT results are used to assess the EOS models and test the mixture rules. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

  9. Nonlinear electrostatic coherent structures: solitary and shock waves in a dissipative, nonplanar multi-component quantum plasma

    NASA Astrophysics Data System (ADS)

    Han, Jiu-Ning; Luo, Jun-Hua; Li, Jun-Xiu

    2014-01-01

    The nonlinear propagation of ion-acoustic solitary and shock waves in a dissipative, nonplanar quantum plasma comprised of electrons, positrons, and ions are studied. A modified Korteweg-de Vries Burgers equation is derived in the limit of low frequency and long wavelength by taking into account the kinematic viscosity among the plasma constituents. It is shown that this plasma system supports the propagation of both compressive and rarefactive nonlinear waves. The effects of variation of various plasma parameters on the time evolution of nonplanar solitary waves, the profile of shock waves, and the nonlinear structure induced by the collision of solitary waves are discussed. It is found that these parameters have significant effects on the properties of nonlinear waves in cylindrical and spherical geometries, and these effects for compressive and rarefactive nonlinear waves are obviously different.

  10. 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.

  11. Reduction of tissue injury in shock-wave lithotripsy by using an acoustic diode.

    PubMed

    Zhu, Songlin; Dreyer, Thomas; Liebler, Marko; Riedlinger, Rainer; Preminger, Glenn M; Zhong, Pei

    2004-05-01

    An acoustic diode (AD) was constructed of two acoustic transparent membranes with good initial contact to allow the transmission of the positive pressure of lithotripter shock wave at an almost unaltered level, yet attenuate significantly its negative pressure, was fabricated. It was evaluated systematically on a Dornier HM-3 lithotripter to assess its application potential to reduce vascular injury without compromising stone fragmentation efficiency during shock-wave lithotripsy. By inserting the AD, the maximum compressive pressure, maximum tensile pressure and tensile duration of the lithotripter shock wave were formed to drop from 49.7 to 47.8 MPa, -7.5 to -7.0 MPa and 6.0 to 5.1 micros, respectively. Damage of a 0.2-mm inner diameter vessel phantom (cellulose hollow fiber) was reduced from rupture after 31 +/- 11 shocks to no rupture after 100 shocks. Maximum bubble size in free-field, maximum dilation of the vessel phantom wall and bubble collapse time became smaller with the use of the AD. However, stone fragmentation showed similar results without a statistically significant difference between the case with and without the AD. All these evidences suggest that the use of an acoustic diode may be a feasible approach to reduce tissue injury without compromising stone comminution in shock-wave lithotripsy. PMID:15183234

  12. 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.

  13. 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.

  14. 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.

  15. Schlieren imaging of shock waves from a trumpet

    NASA Astrophysics Data System (ADS)

    Pandya, Brian H.; Settles, Gary S.; Miller, James D.

    2003-12-01

    A sensitive, large-aperture schlieren optical instrument is applied to observe gas-dynamic phenomena at the exit of a trumpet. Shock waves are seen, especially for loud, high-pitched trumpet notes, and several illustrations are given. Microphone waveforms are given for representative examples. These shock waves arise from the shock-tube-like effect of the performer's intermittent breath pressure driving the cylindrical duct of the trumpet, and are the result of cumulative nonlinear acoustic propagation inside the trumpet bore. They are, however, very weak, traveling only marginally above the acoustic speed. In the 118-124 peak dB(A) range, they are near the weak limit of shock wave visibility by schlieren optics. The schlieren evidence confirms that the frequency of the emitted shock waves corresponds to the frequency of the note being played. Ancillary laminar and turbulent jet phenomena associated with the performer's breath are also visible in the images.

  16. Schlieren imaging of shock waves from a trumpet.

    PubMed

    Pandya, Brian H; Settles, Gary S; Miller, James D

    2003-12-01

    A sensitive, large-aperture schlieren optical instrument is applied to observe gas-dynamic phenomena at the exit of a trumpet. Shock waves are seen, especially for loud, high-pitched trumpet notes, and several illustrations are given. Microphone waveforms are given for representative examples. These shock waves arise from the shock-tube-like effect of the performer's intermittent breath pressure driving the cylindrical duct of the trumpet, and are the result of cumulative nonlinear acoustic propagation inside the trumpet bore. They are, however, very weak, traveling only marginally above the acoustic speed. In the 118-124 peak dB(A) range, they are near the weak limit of shock wave visibility by schlieren optics. The schlieren evidence confirms that the frequency of the emitted shock waves corresponds to the frequency of the note being played. Ancillary laminar and turbulent jet phenomena associated with the performer's breath are also visible in the images. PMID:14714816

  17. Particles and waves Upstream of ICME Driven Interplanetary Shocks

    NASA Astrophysics Data System (ADS)

    Kajdic, P.; Blanco-Cano, X.; Aguilar-Rodriguez, E.; Russell, C. T.; Jian, L.; Opitz, A.; Luhmann, J. G.; Galvin, A. B.

    2011-12-01

    We use STEREO data to study interplanetary shocks driven by coronal mass ejections. We have found ultra-low frequency (ULF, f ~ 0.01 - 0.2 Hz) waves and high-frequency (HF, f ~ 1 Hz) fluctuations in regions upstream and downstream of these shocks. Some of the upstream HF fluctuations were classified as whistler waves. In the past whistler origin has been explained in terms of shock generation. The variety of waves found in the studied regions suggests that some of them may be generated by particle populations (electrons, ions) that can be unstable to different types of instabilities. In this work we study ions and electrons in regions immediately upstream of ten IP shocks of our sample. We use the STEREO SWEA data for electrons and STEREO PLASTIC data for ions. We study particle distributions in different points upstream of the shocks (anisotropies, temperatures, etc.) and investigate which of the observed waves can be generated by backstreaming particles.

  18. 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.

  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. 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.

  1. Response of magnesium single crystals to shock-wave loading at room and elevated temperatures

    NASA Astrophysics Data System (ADS)

    Garkushin, G. V.; Savinykh, A. S.; Kanel, G. I.; Razorenov, S. V.; Jones, D.; Proud, W. G.; Botvina, L. R.

    2014-05-01

    A series of magnesium single crystals, from 0.2 to 3 mm thick, were shock loaded along specific axes, a and c, of the hexagonal closed packed (hcp) structure. Other experiments involved loading at 45 degrees to these principal axes. Shock compression along the c-axis causes inelastic deformation by means of pyramidal slip and twinning and is associated with the largest Hugoniot elastic limit (HEL) for this material. The low-energy basal slip was activated by shock loading along the inclined direction and has he smallest HEL. In all cases, we observe the decay of the elastic precursor wave and growth of the HEL with increasing temperature. For the c-orientation this change is caused by a decrease of elastic constants, not an increase of shear stress along the pyramidal slip planes. For the other orientations the shear stress on the slip planes increased with temperature. For the inclined shock compression, after the HEL, two plastic waves were found: the stress level of the first plastic wave depends on the ultimate shock stress. Finally, the largest spall strength was along the a-axis and the smallest in the off-axis direction.

  2. Analysis of shock-wave propagation in aqueous foams using shock tube experiments

    NASA Astrophysics Data System (ADS)

    Jourdan, G.; Mariani, C.; Houas, L.; Chinnayya, A.; Hadjadj, A.; Del Prete, E.; Haas, J.-F.; Rambert, N.; Counilh, D.; Faure, S.

    2015-05-01

    This paper reports experimental results of planar shock waves interacting with aqueous foams in a horizontal conventional shock tube. Four incident shock wave Mach numbers are considered, ranging from 1.07 to 1.8, with two different foam columns of one meter thickness and expansion ratios of 30 and 80. High-speed flow visualizations are used along with pressure measurements to analyse the main physical mechanisms that govern shock wave mitigation in foams. During the shock/foam interaction, a precursor leading pressure jump was identified as the trace of the liquid film destruction stage in the foam fragmentation process. The corresponding pressure threshold is found to be invariant for a given foam. Regarding the mitigation effect, the results show that the speed of the shock is drastically reduced and that wetter is the foam, slower are the transmitted waves. The presence of the foam barrier attenuates the induced pressure impulse behind the transmitted shock, while the driest foam appears to be more effective, as it limits the pressure induced by the reflected shock off the foam front. Finally, it was found that the pressure histories in the two-phase gas-liquid mixture are different from those previously obtained within a cloud of droplets. The observed behavior is attributed to the process of foam fragmentation and to the modification of the flow topology past the shock. These physical phenomena occurring during the shock/foam interaction should be properly accounted for when elaborating new physical models.

  3. Fiber Bragg Grating sensor for shock wave diagnostics

    NASA Astrophysics Data System (ADS)

    Ravid, Avi; Shafir, Ehud; Zilberman, Shlomi; Berkovic, Garry; Glam, Benny; Appelbaum, Gabriel

    2013-06-01

    Fiber Bragg Grating (FBG) sensor response was studied in gas-gun shock wave experiments. The sensors were embedded in PMMA target subjected to planar shock waves under 1 GPa. Two orientations of the FBG sensor with respect to the shock plane were examined: parallel and perpendicular. The shift of the reflected wavelength was measured with a system based on commonly available communication grade add-drop filters that covered the maximal expected wavelength swing. The FBG sensors survived the shock and their strain-to-wavelength response was determined by comparison to the calculated strain based on the known PMMA EOS and VISAR measurements.

  4. 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.

  5. In vitro interaction of lithotripter shock waves and cytotoxic drugs.

    PubMed Central

    Gambihler, S.; Delius, M.

    1992-01-01

    The effect of a combination of lithotripter shock waves and cytotoxic drugs was examined in vitro. L1210 cells in suspension were exposed to shock waves during incubation with cislatin, doxorubicin, daunorubicin, THP-doxorubicin, or aclacinomycin. Proliferation was determined using the 3-4,5 dimethylthiazol-2,5 diphenyl tetrazolium bromide assay. Dose enhancement ratios were calculated for each drug in order to determine the effect of the additional exposure to shock waves. In addition, partition coefficients and IC50s of the drugs were determined. It was found, that the dose enhancement ratios increased for the drugs with decreasing cytotoxicity. The effect of all five drugs was enhanced by shock waves to a higher degree at 7 min incubation as compared to 50 min incubation. The effect of cisplatin was most significantly enhanced, with a dose enhancement ratio of 6.7 at 7 min incubation. The enhancement increased with the operating voltage used for generating the shock waves, and was only present when cells were exposed to shock waves during the incubation with the drug. An increase in cellular membrane permeability is proposed as the mechanism of interaction between shock waves and drugs. PMID:1637679

  6. 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.

  7. Numerical study of shock-wave/boundary-layer interactions with bleed

    NASA Technical Reports Server (NTRS)

    Hahn, T. O.; Shih, T. I.-P.; Chyu, W. J.

    1993-01-01

    A numerical study was conducted to investigate how bleed through a two-dimensional slot affects shock-wave induced, boundary-layer separation on a flat plate. This study is based on the ensemble-averaged, compressible, Navier-Stokes equations closed by the Baldwin-Lomax, algebraic turbulence model. The algorithm used to obtain solutions was the implicit, partially split, two-factored scheme of Steger. This study examined the effects of the following parameters in controlling shock-wave induced flow separation: location of slot in relation to where the incident shock wave impinged on the boundary layer, size of slot in relation to the boundary-layer thickness, number of slots, spacings between slots, and strength of the incident shock wave. This study also showed the nature of the very complex flowfield about the slot or slots and how the plenum affects the bleed process. The results of this study are relevant to problems where bleed is used to control shock-wave induced, boundary-layer separation (e.g., inside jet engine inlets and wind tunnels).

  8. 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.

  9. 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.

  10. Convection of a pattern of vorticity through a shock wave

    NASA Technical Reports Server (NTRS)

    Ribner, H S

    1954-01-01

    An arbitrary weak spatial distribution of vorticity can be represented in terms of plane sinusoidal shear waves of all orientations and wave lengths (Fourier integral). The analysis treats the passage of a single representative weak shear wave through a plane shock and shows refraction and modification of the shear wave with simultaneous generation of an acoustically intense sound wave. Applications to turbulence and to noise in supersonic wind tunnels are indicated.

  11. Ultra low frequency waves at the Earth's bow shock

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Farris, M. H.

    1995-01-01

    The Earth's bow shock is a bountiful generator of waves. Some of these waves have group velocities that exceed the solar wind velocity directed into the shock and can propagate upstream against the flow. Upstream whistlers observed close to one Hertz in the spacecraft frame have been seen many Earth radii upstream. A second whistler mode wave, called the precursor, propagates upstream along the shock normal but is phase standing in the solar wind flow. The damping of both whistler mode waves is consistent with Landau damping. At low Mach numbers the precursor is connected to the non-coplanarity component in the shock ramp. At higher Mach numbers the upstream waves cannot propagate upstream and ion reflection becomes more important in providing free energy for wave particle interactions. The non-coplanarity component is still present but it now initiates a downstream wave train. Generally the waves just downstream from the bow shock are left hand circularly polarized ion cyclotron waves propagating along the magnetic field at the Alfven velocity. When the upstream Mach number is high and the helium content of the plasma is high, mirror mode waves are observed.

  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. 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.

  15. Mechanism of fragmentation of urinary stones by underwater shock wave.

    PubMed

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

    1988-01-01

    The focusing of an underwater shock wave, generated by an underwater microexplosion, has been studied by several methods, such as holography, pressure measurement and pressure print. It has been shown that the shock wave could be focused within the range of a few millimeters and with an amplitude of 1 kbar. The acoustic impedances of various kinds of urinary stones were measured by the original graphical method using holographic interferrometry. The process of breaking a stone by a focused underwater shock wave was observed with high-speed cinematography. It was supposed that the main mechanism of breaking the stone is the tensile stress at the solid-water acoustic interface. PMID:3201639

  16. 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.

  17. 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

  18. Small scales formation via Alfven wave propagation in compressible nonuniform media

    NASA Technical Reports Server (NTRS)

    Malara, F.; Primavera, L.; Veltri, P.

    1995-01-01

    In weakly dissipative media governed by the magnetohydrodynamics (MHD) equations, any efficient mechanism of energy dissipation requires the formation of small scales. The possibility to produce small scales has been studied by Malara et al. in the case of MHD disturbances propagating in an incompressible and inhomogeneous medium, for a strictly 2D geometry. We extend the work of Malara et al. to include both compressibility and the third component for vector quantities. Using numerical simulations we show that, when an Alfven wave propagates in a compressible nonuniform medium, the two dynamical effects responsible for the small scales formation in the incompressible case are still at work: energy pinching and phase-mixing. Moreover, the interaction between the initial Alfven wave and the inhomogeneity gives rise to the formation of compressible perturbations (fast and slow waves or a static entropy wave). Some of these compressive fluctuations are subject to the steepening of the wave front and become shock waves, which are extremely efficient in dissipating their energy, their dissipation being independent of the Reynolds number. A rough estimate of the typical times which the various dynamical processes take to produce small scales and then to dissipate the energy show that these times are consistent with those required to dissipate inside the solar corona the energy of Alfven waves of photospheric origin.

  19. Isentropic "Shock Waves" in Numerical Simulations of Astrophysical Problems

    NASA Astrophysics Data System (ADS)

    Bisnovatyi-Kogan, G. S.; Moiseenko, S. G.

    2016-03-01

    Strong discontinuities in solutions of the gas dynamic equations under isentropic conditions, i.e., with continuity of entropy at the discontinuity, are examined. Solutions for a standard shock wave with continuity of energy at the discontinuity are compared with those for an isentropic "shock wave." It is shown that numerical simulation of astrophysical problems in which high-amplitude shock waves are encountered (supernova explosions, modelling of jets) with conservation of entropy, rather than of energy, leads to large errors in the shock calculations. The isentropic equations of gas dynamics can be used only when there are no strong discontinuities in the solution or when the intensity of the shocks is not high and they do not significantly affect the flow.

  20. Numerical simulation of the April 24, 1981 interplanetary shock wave

    NASA Astrophysics Data System (ADS)

    Odstrcil, Dusan

    1991-06-01

    The paper deals with the application of the 1D HD computer code to the simulation of the interplanetary shock wave generated on April 24, 1981. This event is simulated, in terms of density, velocity and temperature, by a pulse introduced at 18 Rs into a steady-state solar wind. The observed data were used to specify all significant parameters of the steady-state solar wind and the introduced shock wave. The short duration of the input pulse caused the shock wave to be initially highly decelerated. Special attention is given to the type II radio emission associated with this shock and measured by the Czechoslovak-Soviet experiment aboard the Prognoz-8 satellite. From the given analysis it follows that the emission is generated in front of the shock front at the blended fundamental and harmonic plasma frequency.

  1. Transparency of the strong shock-compressed diamond for 532 nm laser light

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiyu; Zhao, Yang; Yang, Jiamin

    2016-04-01

    An optical reflectivity and transmissivity model for the shock-compressed diamond is established and used to calculate the optical reflectivity and transmissivity of the diamond under different shock compressions. The simulated results indicate that the reflection occurs at the shock front and does not depend on the thickness of the compressed diamond, but the transmissivity decreases with the thickness. The simulated reflectivity is consistent with the experimental results in the literature, which validates the model. It is shown that the diamond keeps transparent when the shock pressure is lower than 2.00 Mbar, and becomes opaque but does not reflect the probe laser as the shock pressure increases from 2.00 Mbar to 4.60 Mbar and reflects the probe laser markedly when the shock pressure is higher than 4.60 Mbar.

  2. 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.

  3. Shock wave perturbation decay in granular materials

    DOE PAGESBeta

    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

  4. 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.

  5. 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.

  6. 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.

  7. 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('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://hdl.handle.net/2060/19710000142','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19710000142"><span id="translatedtitle">Electrical instrument measures position and velocity of <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>Dannenberg, R. E.; Humphry, D. E.</p> <p>1971-01-01</p> <p>Instrument employs a sensor consisting of twin-electrode probe mounted in <span class="hlt">shock</span> tube wall, with small dc voltage impressed across electrodes. Power supply, amplifier, and gate pulse generator complete the system. Instrument provides data for construction of <span class="hlt">wave</span> diagrams, as well as measurement of <span class="hlt">shock</span> velocity.</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://ntrs.nasa.gov/search.jsp?R=19900037939&hterms=roberge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Droberge','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900037939&hterms=roberge&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Droberge"><span id="translatedtitle">A new class of solutions for interstellar 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>Roberge, W. G.; Draine, B. T.</p> <p>1990-01-01</p> <p>An analysis is presented of the equations of motion for steady MHD <span class="hlt">shock</span> <span class="hlt">waves</span> proopagating in interstellar clouds, for boundary conditions that preclude C <span class="hlt">shocks</span>. In addition to J <span class="hlt">shocks</span>, in which the neutral fluid component becomes subsonic at an adiabatic jump front, the equations admit a new class of solutions, called C-asterisk <span class="hlt">shocks</span>, in which the transition to subsonic flow occurs continuously at a sonic point. Numerical methods are developed for computing the structure of J and C-asterisk <span class="hlt">shocks</span> propagating in diffuse interstellar clouds. The effects of chemical, ionization, and recombination processes are included in this treatment. An alternative numerical method, which uses artificial viscosity to facilitate integration through sonic points, is analyzed and shown to be invalid. A set of exemplary solutions, computed for realistic <span class="hlt">shock</span> parameters, shows that C-asterisk <span class="hlt">shocks</span> occur for a broad range of conditions relevant to diffuse interstellar clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7135209','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7135209"><span id="translatedtitle">A new class of solutions for interstellar magnetohydrodynamic <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>Roberge, W.G.; Draine, B.T. Princeton Univ. Observatory, NJ )</p> <p>1990-02-01</p> <p>An analysis is presented of the equations of motion for steady MHD <span class="hlt">shock</span> <span class="hlt">waves</span> propagating in interstellar clouds, for boundary conditions that preclude C <span class="hlt">shocks</span>. In addition to J <span class="hlt">shocks</span>, in which the neutral fluid component becomes subsonic at an adiabatic jump front, the equations admit a new class of solutions, called C-asterisk <span class="hlt">shocks</span>, in which the transition to subsonic flow occurs continuously at a sonic point. Numerical methods are developed for computing the structure of J and C-asterisk <span class="hlt">shocks</span> propagating in diffuse interstellar clouds. The effects of chemical, ionization, and recombination processes are included in this treatment. An alternative numerical method, which uses artificial viscosity to facilitate integration through sonic points, is analyzed and shown to be invalid. A set of exemplary solutions, computed for realistic <span class="hlt">shock</span> parameters, shows that C-asterisk <span class="hlt">shocks</span> occur for a broad range of conditions relevant to diffuse interstellar clouds. 27 refs.</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/2015AIPA....5k7148L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AIPA....5k7148L"><span id="translatedtitle">Traveling <span class="hlt">wave</span> solutions of <span class="hlt">compressible</span> fluid equations and orbital stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Xiang; Zhang, Weiguo; Li, Zhengming</p> <p>2015-11-01</p> <p>In this paper, we discuss the existence of traveling <span class="hlt">wave</span> solutions for <span class="hlt">compressible</span> fluid equations by applying the theory and method of planar dynamical system, and obtain explicit expressions for all bounded traveling <span class="hlt">wave</span> solutions by undetermined coefficient method, including kink and bell profile traveling <span class="hlt">wave</span> solutions, as well as periodic <span class="hlt">wave</span> solutions. We prove the kink profile solitary <span class="hlt">wave</span> solution, both sides of which asymptotic values are not zero, is orbitally stable by the theory of Grillakis-Shatah-Strauss orbital stability.</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> <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/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> </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://www.osti.gov/scitech/servlets/purl/548730','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/548730"><span id="translatedtitle">Spall <span class="hlt">wave</span>-profile and <span class="hlt">shock</span>-recovery experiments on depleted uranium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hixson, R.S.; Vorthman, J.E.; Gustavsen, R.L.; Zurek, A.K.; Thissell, W.R.; Tonks, D.L.</p> <p>1997-11-01</p> <p>Depleted Uranium of two different purity levels has been studied to determine spall strength under <span class="hlt">shock</span> <span class="hlt">wave</span> loading. A high purity material with approximately 30 ppm of carbon impurities was <span class="hlt">shock</span> <span class="hlt">compressed</span> to two different stress levels, 37 and 53 kbar. The second material studied was uranium with about 300 ppm of carbon impurities. This material was <span class="hlt">shock</span> loaded to three different final stress level, 37, 53, and 81 kbar. Two experimental techniques were used in this work. First, time-resolved free surface particle velocity measurements were done using a VISAR velocity interferometer. The second experimental technique used was soft recovery of samples after <span class="hlt">shock</span> loading. These two experimental techniques will be briefly described here and VISAR results will be shown. Results of the spall recovery experiments and subsequent metallurgical analyses are described in another paper in these proceedings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AIPC.1426..755C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012AIPC.1426..755C&link_type=ABSTRACT"><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/2001AIPC..593...99L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AIPC..593...99L"><span id="translatedtitle">More efficient focusing for extracorporeal <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>Loske, Achim M.; Prieto, Fernando E.</p> <p>2001-10-01</p> <p>The purpose of this study was to generate alternative pressure waveforms in order to increase efficiency during non-invasive treatments of nephrolithiasis. Two new systems for electrohydraulic <span class="hlt">shock</span> <span class="hlt">wave</span> generators were tested. These devices generate two pressure pulses, instead of only one positive peak, followed by a trough, as in conventional systems. Pressure measurements and stone fragmentation efficiency were compared to that of conventional <span class="hlt">shock</span> <span class="hlt">wave</span> generators, using needle hydrophones and kidney-stone models.</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="http://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/526961','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/526961"><span id="translatedtitle">Temperature maxima in stable two-dimensional <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>Kum, O.; Hoover, W.G.; Hoover, C.G.</p> <p>1997-07-01</p> <p>We use molecular dynamics to study the structure of moderately strong <span class="hlt">shock</span> <span class="hlt">waves</span> in dense two-dimensional fluids, using Lucy{close_quote}s pair potential. The stationary profiles show relatively broad temperature maxima, for both the longitudinal and the average kinetic temperatures, just as does Mott-Smith{close_quote}s model for strong <span class="hlt">shock</span> <span class="hlt">waves</span> in dilute three-dimensional gases. {copyright} {ital 1997} {ital The American Physical Society}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16297828','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16297828"><span id="translatedtitle">The role of extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> on plantar fasciitis.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Roehrig, Gregory J; Baumhauer, Judith; DiGiovanni, Benedict F; Flemister, Adolph S</p> <p>2005-12-01</p> <p>Extracorporeal <span class="hlt">shock</span> <span class="hlt">wave</span> therapy for chronic plantar fasciitis has been under investigation since its advent in the early 1990s. Its use has been approved by the U.S. Food and Drug Administration; however, much controversy exists surrounding its mechanism of action, treatment protocols, and clinical efficacy. This article reviews some of the existing theories, opinions, and data in an attempt to summarize the current role that <span class="hlt">shock</span> <span class="hlt">wave</span> therapy plays in the treatment of plantar fasciitis. PMID:16297828</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993PMTF....1...34F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993PMTF....1...34F"><span id="translatedtitle">Efficiency of <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation in ducts by various methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frolov, S. M.</p> <p>1993-02-01</p> <p>Different methods of <span class="hlt">shock</span> <span class="hlt">wave</span> attenuation in ducts are compared in terms of efficiency. The methods investigated include expansion of the duct cross section, the use of perforated side walls, and the use of porous screens and screen cascades. The attentuation of air <span class="hlt">shock</span> <span class="hlt">waves</span> is estimated by using a unified approach which provides satisfactory agreement with experimental data. Based on the results of the study, a nomogram is plotted which can be used for practical calculations.</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.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://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('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://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('http://ntrs.nasa.gov/search.jsp?R=19930062098&hterms=dynamics+electromagnetics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Ddynamics%2Belectromagnetics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930062098&hterms=dynamics+electromagnetics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Ddynamics%2Belectromagnetics"><span id="translatedtitle">Electromagnetic ion cyclotron <span class="hlt">waves</span> stimulated by modest magnetospheric <span class="hlt">compressions</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, B. J.; Hamilton, D. C.</p> <p>1993-01-01</p> <p>AMPTE/CCE magnetic field and particle data are used to test the suggestion that increased hot proton temperature anisotropy resulting from convection during magnetospheric <span class="hlt">compression</span> is responsible for the enhancement in Pc 1 emission via generation of electromagnetic ion cyclotron (EMIC) <span class="hlt">waves</span> in the dayside outer equatorial magnetosphere. The relative increase in magnetic field is used to gauge the strength of the <span class="hlt">compression</span>, and an image dipole model is used to estimate the motion of the plasma during <span class="hlt">compression</span>. Proton data are used to analyze the evolution of the proton distribution and the corresponding changes in EMIC <span class="hlt">wave</span> activity expected during the <span class="hlt">compression</span>. It is suggested that enhancements in dynamic pressure pump the energetic proton distributions in the outer magnetosphere, driving EMIC <span class="hlt">waves</span>. <span class="hlt">Waves</span> are expected to be generated most readily close to the magnetopause, and transient pressure pulses may be associated with bursts of EMIC <span class="hlt">waves</span>, which would be observed on the ground in association with ionospheric transient signatures.</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="http://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/2060/20020080810','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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2923385','PMC'); return false;" href="http://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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003Ap%26SS.287..111H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003Ap%26SS.287..111H"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">Waves</span> in Outflows from Young Stars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartigan, Patrick</p> <p></p> <p>This review focuses on physics of the cooling zones behind radiative <span class="hlt">shocks</span> and the emission line diagnostics that can be used to infer physical conditions and mass loss rates in jets from young stars. Spatial separations of the cooling zones from the <span class="hlt">shock</span> fronts, now resolvable with HST, and recent evidence for C-<span class="hlt">shocks</span> have greatly increased our understanding of how <span class="hlt">shocks</span> in outflows interact with the surrounding medium and with other material within the flow. By combining multiple epoch HST images, one can create `movies' of flows like those produced from numerical codes, and learn what kinds of instabilities develop within these systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21185651','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21185651"><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://www.osti.gov/scitech">SciTech Connect</a></p> <p>Feng, R.; Gupta, Y. M.; Yuan, G.</p> <p>1998-07-10</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> </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://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 PAGESBeta</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/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://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="http://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/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://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('http://ntrs.nasa.gov/search.jsp?R=19910060876&hterms=upstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D80%26Ntt%3Dupstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910060876&hterms=upstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DTitle%26N%3D0%26No%3D80%26Ntt%3Dupstream"><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/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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4530210','PMC'); return false;" href="http://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://www.ncbi.nlm.nih.gov/pubmed/22554068','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22554068"><span id="translatedtitle">Ultrafast <span class="hlt">shock</span> <span class="hlt">compression</span> and <span class="hlt">shock</span>-induced decomposition of 1,3,5-triamino-2,4,6-trinitrobenzene subjected to a subnanosecond-duration <span class="hlt">shock</span>: an analysis of decomposition products.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carter, Jeffrey A; Zaug, Joseph M; Nelson, A J; Armstrong, Michael R; Manaa, M Riad</p> <p>2012-05-24</p> <p><span class="hlt">Shock</span> <span class="hlt">compression</span> studies of pressed and confined ultrafine 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) powder were conducted using ultrashort ~300 ps, ~50 GPa <span class="hlt">shock</span> <span class="hlt">waves</span>. The recovered decomposition products were characterized using X-ray photoelectron spectroscopy, infrared spectroscopy, and Raman spectroscopy. A substantial amount of <span class="hlt">shock</span>-related chemistry was observed. Approximately 75% of the nitrogen atoms were liberated as gas-phase species, along with ~33% of the oxygen atoms, as a result of the applied <span class="hlt">shock</span>. Furthermore, we observe C 1s binding energies suggesting the formation of sp(3) hybridized amorphous carbon. For comparison, a carbon nitride material was also prepared and characterized by thermally pyrolizing TATB. The <span class="hlt">shock-compressed</span> TATB and the thermally pyrolized TATB are qualitatively different, suggesting that, carbon nitrides, a possible indicator of nitrogen-rich heterocycles precursors, are not a major product class for strongly overdriven <span class="hlt">shock</span> conditions. These experimental conditions were, however, not detonation conditions, and the possible formation of nitrogen-rich heterocycles in actual detonations still exists. PMID:22554068</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/2016EGUGA..18.3009G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.3009G"><span id="translatedtitle"><span class="hlt">Waves</span> associated with interplanetary <span class="hlt">shocks</span>: Types and properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goncharov, Oleksandr; Nemecek, Zdenek; Safrankova, Jana; Prech, Lubomir; Koval, Andriy; Wilson, Lynn B., III; Zastenker, Georgy N.</p> <p>2016-04-01</p> <p>Interplanetary (IP) <span class="hlt">shocks</span> are often associated with high-frequency (several Hz) <span class="hlt">wave</span> packets in both upstream and downstream regions. These <span class="hlt">waves</span> could be resolved in Wind fast magnetic field data but the time resolution of plasma instruments is insufficient for their detection. The BMSW instrument onboard the Spektr-R spacecraft measures solar wind parameters with a resolution of 32 ms and it allows a detailed analysis of these <span class="hlt">waves</span>. Our previous analysis of subcritical low-Mach-number fast forward <span class="hlt">shocks</span> has shown that the both upstream and downstream <span class="hlt">waves</span> conserve over the spacecraft separation of the order of 200 Re and their wavelengths are directly proportional to the <span class="hlt">shock</span> ramp thickness that is controlled by the ion thermal gyroradius. Comparing observations of both Wind and Spektr-R spacecraft, we discuss a nature of these <span class="hlt">waves</span> in both regions and their properties and their dependence on upstream solar wind and magnetic field parameters.</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/2015EUCAS...7..437G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EUCAS...7..437G"><span id="translatedtitle">A new configuration of irregular reflection of <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>Gvozdeva, L. G.; Gavrenkov, S. A.</p> <p>2015-06-01</p> <p>A new configuration of <span class="hlt">shock</span> <span class="hlt">waves</span> has been found in the reflection of <span class="hlt">shock</span> <span class="hlt">waves</span> in a stationary supersonic gas flow in addition to the wellknown regular and Mach reflections. This new three-<span class="hlt">shock</span> configuration occurs with a negative angle of reflection and Mach numbers greater than 3 and an adiabatic index smaller than 1.4. It has been shown that this new configuration is unstable and leads to a radical change of the total flow pattern. The emergence of this new kind of instability can negatively affect operation of aircraft and rocket engines due to the failure of the flow to be as conventionally predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JAP....88.2371Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JAP....88.2371Y"><span id="translatedtitle"><span class="hlt">Shock</span> <span class="hlt">wave</span> response of ammonium perchlorate single crystals to 6 GPa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yuan, G.; Feng, R.; Gupta, Y. M.; Zimmerman, K.</p> <p>2000-09-01</p> <p>Plane <span class="hlt">shock</span> <span class="hlt">wave</span> experiments were carried out on ammonium perchlorate single crystals <span class="hlt">compressed</span> along [210] and [001] orientations to peak stresses ranging from 1.2 to 6.2 GPa. Quartz gauge and velocity interferometer techniques were used to measure the elastic and plastic <span class="hlt">shock</span> <span class="hlt">wave</span> velocities, and stress and particle velocity histories in the <span class="hlt">shocked</span> samples. The measured Hugoniot elastic limit (HEL) was 0.48±0.09 GPa. Above the HEL and up to about 6 GPa, the data show a clear two-<span class="hlt">wave</span> structure, indicating an elastic-plastic response. Time-dependent elastic precursor decay and plastic <span class="hlt">wave</span> ramping are discernable and orientation dependent in the low stress data. However, the orientation dependence of the peak state response is small. Hence, data for both orientations were summarized into a single isotropic, elastic-plastic-stress relaxation model. Reasonable agreement was obtained between the numerical simulations using this model and the measured <span class="hlt">wave</span> profiles. At a <span class="hlt">shock</span> stress of about 6 GPa and for the time duration and crystal orientations examined, we did not observe any features that may be identified as a sustained chemical reaction or a phase transformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.Z4003S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.Z4003S"><span id="translatedtitle">Observations on the nucleation of ice VII in <span class="hlt">shock</span> <span class="hlt">compressed</span> water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stafford, Samuel J. P.; Chapman, David J.; Eakins, Daniel E.; Bland, Simon N.</p> <p>2015-06-01</p> <p>The ability of water to freeze into the ice VII phase under dynamic <span class="hlt">compression</span> is a good example of a liquid to solid phase change. The ice VII is thought to nucleate and grow from the window surfaces in a relatively slow process (on the order of 100ns) that can be seen in <span class="hlt">wave</span> profiles and a visible darkening of the sample. On silica windows the process is evident but from sapphire surfaces the heterogeneous nucleation appears to be entirely absent and the water remains metastable. To investigate the influence of silica, and under what conditions sapphire might heterogeneously nucleate ice VII, we present an experimental technique incorporating multiple liquid targets diagnosed with PDV and high speed imaging of the nucleation process from a variety of surfaces and additives. The Institute of <span class="hlt">Shock</span> Physics acknowledges the continued support of AWE and Imperial College London.</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/2012pbdm.book..403L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012pbdm.book..403L"><span id="translatedtitle">Generation of Focused <span class="hlt">Shock</span> <span class="hlt">Waves</span> in Water for Biomedical Applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lukeš, Petr; Šunka, Pavel; Hoffer, Petr; Stelmashuk, Vitaliy; Beneš, Jiří; Poučková, Pavla; Zadinová, Marie; Zeman, Jan</p> <p></p> <p>The physical characteristics of focused two-successive (tandem) <span class="hlt">shock</span> <span class="hlt">waves</span> (FTSW) in water and their biological effects are presented. FTSW were ­generated by underwater multichannel electrical discharges in a highly conductive saline solution using two porous ceramic-coated cylindrical electrodes of different diameter and surface area. The primary cylindrical pressure <span class="hlt">wave</span> generated at each composite electrode was focused by a metallic parabolic reflector to a common focal point to form two strong <span class="hlt">shock</span> <span class="hlt">waves</span> with a variable time delay between the <span class="hlt">waves</span>. The pressure field and interaction between the first and the second <span class="hlt">shock</span> <span class="hlt">waves</span> at the focus were investigated using schlieren photography and polyvinylidene fluoride (PVDF) <span class="hlt">shock</span> gauge sensors. The largest interaction was obtained for a time delay of 8-15 μs between the <span class="hlt">waves</span>, producing an amplitude of the negative pressure phase of the second <span class="hlt">shock</span> <span class="hlt">wave</span> down to -80 MPa and a large number of cavitations at the focus. The biological effects of FTSW were demonstrated in vitro on damage to B16 melanoma cells, in vivo on targeted lesions in the thigh muscles of rabbits and on the growth delay of sarcoma tumors in Lewis rats treated in vivo by FTSW, compared to untreated controls.</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://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=heat+absorbing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dheat%2Babsorbing','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19720035837&hterms=heat+absorbing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dheat%2Babsorbing"><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> </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://adsabs.harvard.edu/abs/2016PhPl...23c2704P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23c2704P"><span id="translatedtitle">Hydrodynamic growth and decay of planar <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>Piriz, A. R.; Sun, Y. B.; Tahir, N. A.</p> <p>2016-03-01</p> <p>A model for the hydrodynamic attenuation (growth and decay) of planar <span class="hlt">shocks</span> is presented. The model is based on the approximate integration of the fluid conservation equations, and it does not require the heuristic assumptions used in some previous works. A key issue of the model is that the boundary condition on the piston surface is given by the retarded pressure, which takes into account the transit time of the sound <span class="hlt">waves</span> between the piston and any position at the bulk of the <span class="hlt">shocked</span> fluid. The model yields the <span class="hlt">shock</span> pressure evolution for any given pressure pulse on the piston, as well as the evolution of the trajectories, velocities, and accelerations on the <span class="hlt">shock</span> and piston surfaces. An asymptotic analytical solution is also found for the decay of the <span class="hlt">shock</span> <span class="hlt">wave</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790041960&hterms=upstream+downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dupstream%2Bdownstream','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790041960&hterms=upstream+downstream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dupstream%2Bdownstream"><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/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/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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940007618','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940007618"><span id="translatedtitle">Initiating solar system formation through stellar <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>Boss, A. P.; Myhill, E. A.</p> <p>1993-01-01</p> <p>Isotopic anomalies in presolar grains and other meteoritical components require nucleosynthesis in stellar interiors, condensation into dust grains in stellar envelopes, transport of the grains through the interstellar medium by stellar outflows, and finally injection of the grains into the presolar nebula. The proximity of the presolar cloud to these energetic stellar events suggests that a <span class="hlt">shock</span> <span class="hlt">wave</span> from a stellar outflow might have initiated the collapse of an otherwise stable presolar cloud. We have begun to study the interactions of stellar <span class="hlt">shock</span> <span class="hlt">waves</span> with thermally supported, dense molecular cloud cores, using a three spatial dimension (3D) radiative hydrodynamics code. Supernova <span class="hlt">shock</span> <span class="hlt">waves</span> have been shown by others to destroy quiescent clouds, so we are trying to determine if the much smaller <span class="hlt">shock</span> speeds found in, e.g., asymptotic giant branch (AGB) star winds, are strong enough to initiate collapse in an otherwise stable, rotating, solar-mass cloud core, without leading to destruction of the cloud.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ShWav.tmp...14G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ShWav.tmp...14G"><span id="translatedtitle">Explosive-driven <span class="hlt">shock</span> <span class="hlt">wave</span> and vortex ring interaction with a propane flame</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giannuzzi, P. M.; Hargather, M. J.; Doig, G. C.</p> <p>2016-02-01</p> <p>Experiments were performed to analyze the interaction of an explosively driven <span class="hlt">shock</span> <span class="hlt">wave</span> and a propane flame. A 30 g explosive charge was detonated at one end of a 3-m-long, 0.6-m-diameter <span class="hlt">shock</span> tube to produce a <span class="hlt">shock</span> <span class="hlt">wave</span> which propagated into the atmosphere. A propane flame source was positioned at various locations outside of the <span class="hlt">shock</span> tube to investigate the effect of different strength <span class="hlt">shock</span> <span class="hlt">waves</span>. High-speed retroreflective shadowgraph imaging visualized the <span class="hlt">shock</span> <span class="hlt">wave</span> motion and flame response, while a synchronized color camera imaged the flame directly. The explosively driven <span class="hlt">shock</span> tube was shown to produce a repeatable <span class="hlt">shock</span> <span class="hlt">wave</span> and vortex ring. Digital streak images show the <span class="hlt">shock</span> <span class="hlt">wave</span> and vortex ring propagation and expansion. The shadowgrams show that the <span class="hlt">shock</span> <span class="hlt">wave</span> extinguishes the propane flame by pushing it off of the fuel source. Even a weak <span class="hlt">shock</span> <span class="hlt">wave</span> was found to be capable of extinguishing the flame.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AIPC.1216..629S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AIPC.1216..629S"><span id="translatedtitle">Energetic Particles and Upstream <span class="hlt">Waves</span> at Co-rotating <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>Smith, Edward J.; Zhou, Xiaoyan</p> <p>2010-03-01</p> <p>We report a study of energetic ion acceleration at <span class="hlt">shocks</span> bounding co-rotating interaction regions (CIRs). Archived data obtained by Ulysses magnetic field, solar wind and energetic particle investigations at low latitude CIRs have been assembled and analyzed. The statistical relations between various properties of 22 Forward <span class="hlt">shocks</span>, energetic particles and upstream heliospheric magnetic field fluctuations are presented. No statistically significant correlations are found between the <span class="hlt">shock</span> <span class="hlt">compression</span> ratio, r, or the particle intensity, jp, or the energetic particle spectral index, s, and the <span class="hlt">shock</span> normal-upstream field angle, θBn. Furthermore, a theoretical relation between the particle spectral index and <span class="hlt">shock</span> <span class="hlt">compression</span> is not consistent with the observed values of s and r. The particle intensities are poorly correlated with the power in upstream heliospheric magnetic field fluctuations contrary to our preliminary study of fewer <span class="hlt">shocks</span>. We conclude that many of the expectations of Diffusive <span class="hlt">Shock</span> Theory are not supported by this data set but it is too early to decide whether some key measurement is missing or the theory needs reconsideration.</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('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://adsabs.harvard.edu/abs/2016JPhCS.710a2011A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.710a2011A"><span id="translatedtitle"><span class="hlt">Compressive</span> and Shear <span class="hlt">Wave</span> Velocity Profiles using Seismic Refraction Technique</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aziman, M.; Hazreek, Z. A. M.; Azhar, A. T. S.; Haimi, D. S.</p> <p>2016-04-01</p> <p>Seismic refraction measurement is one of the geophysics exploration techniques to determine soil profile. Meanwhile, the borehole technique is an established way to identify the changes of soil layer based on number of blows penetrating the soil. Both techniques are commonly adopted for subsurface investigation. The seismic refraction test is a non-destructive and relatively fast assessment compared to borehole technique. The soil velocities of <span class="hlt">compressive</span> <span class="hlt">wave</span> and shear <span class="hlt">wave</span> derived from the seismic refraction measurements can be directly utilised to calculate soil parameters such as soil modulus and Poisson’s ratio. This study investigates the seismic refraction techniques to obtain <span class="hlt">compressive</span> and shear <span class="hlt">wave</span> velocity profile. Using the vertical and horizontal geophones as well as vertical and horizontal strike directions of the transient seismic source, the propagation of <span class="hlt">compressive</span> <span class="hlt">wave</span> and shear <span class="hlt">wave</span> can be examined, respectively. The study was conducted at Sejagung Sri Medan. The seismic velocity profile was obtained at a depth of 20 m. The velocity of the shear <span class="hlt">wave</span> is about half of the velocity of the <span class="hlt">compression</span> <span class="hlt">wave</span>. The soil profiles of <span class="hlt">compressive</span> and shear <span class="hlt">wave</span> velocities were verified using the borehole data and showed good agreement with the borehole data.</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/2000IJNMF..33..313G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000IJNMF..33..313G"><span id="translatedtitle">Robustness versus accuracy in <span class="hlt">shock-wave</span> computations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gressier, Jérémie; Moschetta, Jean-Marc</p> <p>2000-06-01</p> <p>Despite constant progress in the development of upwind schemes, some failings still remain. Quirk recently reported (Quirk JJ. A contribution to the great Riemann solver debate. International Journal for Numerical Methods in Fluids 1994; 18: 555-574) that approximate Riemann solvers, which share the exact capture of contact discontinuities, generally suffer from such failings. One of these is the odd-even decoupling that occurs along planar <span class="hlt">shocks</span> aligned with the mesh. First, a few results on some failings are given, namely the carbuncle phenomenon and the kinked Mach stem. Then, following Quirk's analysis of Roe's scheme, general criteria are derived to predict the odd-even decoupling. This analysis is applied to Roe's scheme (Roe PL, Approximate Riemann solvers, parameters vectors, and difference schemes, Journal of Computational Physics 1981; 43: 357-372), the Equilibrium Flux Method (Pullin DI, Direct simulation methods for <span class="hlt">compressible</span> inviscid ideal gas flow, Journal of Computational Physics 1980; 34: 231-244), the Equilibrium Interface Method (Macrossan MN, Oliver. RI, A kinetic theory solution method for the Navier-Stokes equations, International Journal for Numerical Methods in Fluids 1993; 17: 177-193) and the AUSM scheme (Liou MS, Steffen CJ, A new flux splitting scheme, Journal of Computational Physics 1993; 107: 23-39). Strict stability is shown to be desirable to avoid most of these flaws. Finally, the link between marginal stability and accuracy on shear <span class="hlt">waves</span> is established. Copyright</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850066354&hterms=application+data+science&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dapplication%2Bdata%2Bscience','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850066354&hterms=application+data+science&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dapplication%2Bdata%2Bscience"><span id="translatedtitle">Application of <span class="hlt">shock</span> <span class="hlt">wave</span> data to earth and planetary science</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ahrens, T. J.</p> <p>1985-01-01</p> <p>It is pointed out that <span class="hlt">shock</span> <span class="hlt">wave</span> data for: (1) low temperature condensable gases H2 and He, (2) H2O, CH4, NH3, CO, CO2, and N2 ices, and (3) silicates, metals, oxides and sulfides have many applications in geophysics and planetary science. The present paper is concerned with such applications. The composition of planetary interiors is discussed, taking into account the division of the major constituent of the planets in three groups on the basis of 'cosmic abundance' arguments, the H-He mixtures in the case of Jupiter and Saturn, <span class="hlt">shock</span> <span class="hlt">wave</span> data for hydrogen, and constraints on the internal structure of Uranus and Neptune. Attention is also given to the earth's mantle, <span class="hlt">shock</span> <span class="hlt">wave</span> data for mantle materials, the earth's core, impacts on planetary surfaces, elastic <span class="hlt">wave</span> velocities as a function of pressure along the Hugoniot of iron, and reactions which yield the CO2 bearing atmospheres for Venus, earth, and Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..SHK.F1019F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..SHK.F1019F"><span id="translatedtitle">Recording of Phase Transition in Tin in <span class="hlt">Shock</span> and Release <span class="hlt">Waves</span> Using Laser Interferometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Finyushin, Stanislav; Fedorov, Alexey; Mikhailov, Anatoliy; Nazarov, Dmitriy; Chudakov, Evgeniy; Kalashnikov, Denis; Trunin, Ivan; Tereshkina, Irina</p> <p>2013-06-01</p> <p>In this paper the authors present results of experiments, concerning the recording of free surface velocity and particle velocity of tin/LiF window interface of tin sample at the dynamic pressure in the range 10 to 70 GPa, using laser interferometry methods Fabry-Perot and PDV. The features of recorded velocity histories interpreted the polymorphous transitions (the direct β - γ phase transition, the reverse γ - β phase transition) and some points on tin melting curve. The tin samples were loaded by impactor accelerated by explosion products of HE cartridge (the <span class="hlt">wave</span> with the rectangular profile) or by direct detonation <span class="hlt">wave</span> of HE layer (the <span class="hlt">wave</span> with the decaying profile). With the help of PDV method, velocity of particles cloud was recorded with the free surface velocity at the moment when the <span class="hlt">shock</span> <span class="hlt">wave</span> front arrived to the tin free surface with the pressure amplitude of P >= 19 GPa. This could is corresponded to appearing of the liquid-solid phase at the release <span class="hlt">wave</span>. The tin melting in the <span class="hlt">shock</span> <span class="hlt">wave</span> is recorded at the loading pressure of P >= 51 GPa. The pressure and temperature numerical simulations were performed for <span class="hlt">shock</span> <span class="hlt">compression</span> and the further releasing of tin.</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/2009APS..DFD.K1001C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..DFD.K1001C"><span id="translatedtitle">Unsteadiness of <span class="hlt">Shock</span> <span class="hlt">Wave</span> / 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>Clemens, Noel</p> <p>2009-11-01</p> <p><span class="hlt">Shock</span> <span class="hlt">wave</span> / boundary layer interactions are an important feature of high-speed flows that occur in a wide range of practical configurations including aircraft control surfaces, inlets, missile base flows, nozzles, and rotating machinery. These interactions are often associated with severe boundary layer separation, which is highly unsteady, and exhibits high fluctuating pressure and heat loads. The unsteady motions are characterized by a wide range of frequencies, including low-frequency motions that are about two orders of magnitude lower than those that characterize the upstream boundary layer. It is these low-frequency motions that are of most interest because they have been the most difficult to explain and model. Despite significant work over the past few decades, the source of the low-frequency motions remains a topic of intense debate. Owing to a flurry of activity over the past decade on this single topic we are close to developing a comprehensive understanding of the low-frequency unsteadiness. For example, recent work in our laboratory and others suggests that the driving mechanism is related to low-frequency fluctuations in the upstream boundary layer. However, several recent studies suggest the dominant mechanism is an intrinsic instability of the separated flow. Here we attempt to reconcile these views by arguing that the low-frequency unsteadiness is driven by both upstream and downstream processes, but the relative importance of each mechanism depends on the strength (or length-scale) of separation. In cases where the separation bubble is relatively small, then the flow is intermittently separated, and there exists a strong correlation between upstream velocity fluctuations and the separation bubble dynamics. It appears that superstructures in the upstream boundary layer can play an important role in driving the unsteadiness for this case. It is not clear, however, if the upstream fluctuations directly move the separation point or indirectly couple</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/2007JaJAP..46.4497C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JaJAP..46.4497C"><span id="translatedtitle"><span class="hlt">Compression</span> <span class="hlt">Wave</span> Velocity of Cylindrical Rock Specimens: Engineering Modulus Interpretation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cha, Minsu; Cho, Gye-Chun</p> <p>2007-07-01</p> <p>In this study, we experimentally assess which elastic modulus — Young’s modulus or the constraint modulus — is appropriate for application to the <span class="hlt">compression</span> <span class="hlt">wave</span> velocity of rock cores measured via an ultrasonic pulse technique and a point-source travel-time method. Experimental tests are performed at pulse frequencies between 50 kHz and 1 MHz, the ratio of diameter (D) to wavelength (λ) is between 0.6 and 25.6, and the specimen length is between 10 and 70 cm. It is found that <span class="hlt">compression</span> <span class="hlt">wave</span> velocities obtained from the two methods are constrained <span class="hlt">wave</span> velocities, and thus the constraint modulus should be applied in the <span class="hlt">wave</span> equation. Also, the effect of the frequency of the ultrasonic pulse, D/λ, and specimen length on <span class="hlt">compression</span> <span class="hlt">wave</span> velocity is negligble within the ranges explored in this study.</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> </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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