Sample records for relativistic blast wave

  1. Baryon Loaded Relativistic Blast Waves in Supernovae

    Microsoft Academic Search

    Sayan Chakraborti; Alak Ray

    2011-01-01

    We provide a new analytic blast wave solution which generalizes the Blandford-McKee solution to arbitrary ejecta masses and Lorentz factors. Until recently relativistic supernovae have been discovered only through their association with long-duration gamma-ray bursts (GRBs). The blast waves of such explosions are well described by the Blandford-McKee (in the ultra-relativistic regime) and Sedov-Taylor (in the non-relativistic regime) solutions during

  2. A SEMI-ANALYTIC FORMULATION FOR RELATIVISTIC BLAST WAVES WITH A LONG-LIVED REVERSE SHOCK

    SciTech Connect

    Uhm, Z. Lucas, E-mail: uhm@iap.fr [Institut d'Astrophysique de Paris, UMR 7095 Universite Pierre et Marie Curie-Paris 6 - CNRS, 98 bis boulevard Arago, 75014 Paris (France)

    2011-06-01

    This paper performs a semi-analytic study of relativistic blast waves in the context of gamma-ray bursts. Although commonly used in a wide range of analytical and numerical studies, the equation of state (EOS) with a constant adiabatic index is a poor approximation for relativistic hydrodynamics. Adopting a more realistic EOS with a variable adiabatic index, we present a simple form of jump conditions for relativistic hydrodynamical shocks. Then we describe in detail our technique of modeling a very general class of GRB blast waves with a long-lived reverse shock. Our technique admits an arbitrary radial stratification of the ejecta and ambient medium. We use two different methods to find dynamics of the blast wave: (1) customary pressure balance across the blast wave and (2) the 'mechanical model'. Using a simple example model, we demonstrate that the two methods yield significantly different dynamical evolutions of the blast wave. We show that the pressure balance does not satisfy the energy conservation for an adiabatic blast wave while the mechanical model does. We also compare two sets of afterglow light curves obtained with the two different methods.

  3. Dynamics and stability of relativistic gamma-ray-bursts blast waves

    NASA Astrophysics Data System (ADS)

    Meliani, Z.; Keppens, R.

    2010-09-01

    Aims: In gamma-ray-bursts (GRBs), ultra-relativistic blast waves are ejected into the circumburst medium. We analyse in unprecedented detail the deceleration of a self-similar Blandford-McKee blast wave from a Lorentz factor 25 to the nonrelativistic Sedov phase. Our goal is to determine the stability properties of its frontal shock. Methods: We carried out a grid-adaptive relativistic 2D hydro-simulation at extreme resolving power, following the GRB jet during the entire afterglow phase. We investigate the effect of the finite initial jet opening angle on the deceleration of the blast wave, and identify the growth of various instabilities throughout the coasting shock front. Results: We find that during the relativistic phase, the blast wave is subject to pressure-ram pressure instabilities that ripple and fragment the frontal shock. These instabilities manifest themselves in the ultra-relativistic phase alone, remain in full agreement with causality arguments, and decay slowly to finally disappear in the near-Newtonian phase as the shell Lorentz factor drops below 3. From then on, the compression rate decreases to levels predicted to be stable by a linear analysis of the Sedov phase. Our simulations confirm previous findings that the shell also spreads laterally because a rarefaction wave slowly propagates to the jet axis, inducing a clear shell deformation from its initial spherical shape. The blast front becomes meridionally stratified, with decreasing speed from axis to jet edge. In the wings of the jetted flow, Kelvin-Helmholtz instabilities occur, which are of negligible importance from the energetic viewpoint. Conclusions: Relativistic blast waves are subject to hydrodynamical instabilities that can significantly affect their deceleration properties. Future work will quantify their effect on the afterglow light curves.

  4. Production of Kaon and $?$ in nucleus-nucleus collisions at ultra-relativistic energy from a blast wave model

    E-print Network

    Song Zhang; Yu-Gang Ma; Jin-Hui Chen; Chen Zhong

    2014-11-06

    The particle production of Kaon and $\\Lambda$ are studied in nucleus-nucleus collisions at relativistic energy based on a chemical equilibrium blast-wave model. The transverse momentum spectra of Kaon and $\\Lambda$ at the kinetic freeze-out stage from our model are in good agreement with the experimental results. The kinetic freeze-out parameters of temperature ($T_{kin}$) and radial flow parameter $\\rho_{0}$ are presented for the FOPI, RHIC and LHC energies. And the resonance decay effect is also discussed. The systematic study for beam energy dependence of the strangeness particle production will help us to better understand the properties of the matter created in heavy-ion collisions at the kinetic freeze-out stage.

  5. Spectra and radial flow in relativistic heavy ion collisions with Tsallis statistics in a blast-wave description

    SciTech Connect

    Tang Zebo; Xu Yichun [University of Science and Technology of China, Hefei 230026 (China); Ruan Lijuan; Buren, Gene van; Xu Zhangbu [Brookhaven National Laboratory, Upton, New York 11973 (United States); Wang Fuqiang [Purdue University, West Lafayette, Indiana 47907 (United States)

    2009-05-15

    We have implemented the Tsallis statistics in a Blast-Wave model (TBW) and applied it to midrapidity transverse-momentum spectra of identified particles measured at BNL Relativistic Heavy Ion Collider (RHIC). This new TBW function fits the RHIC data very well for p{sub T}<3 GeV/c. We observed that the collective flow velocity starts from zero in p+p and peripheral Au+Au collisions and grows to 0.470{+-}0.009c in central Au+Au collisions. The resulting (q-1) parameter, which characterizes the degree of nonequilibrium in a system, indicates an evolution from a highly nonequilibrated system in p+p collisions toward an almost thermalized system in central Au+Au collisions. The temperature and collective velocity are well described by a quadratic dependence on (q-1). Two sets of parameters in our TBW are required to describe the meson and baryon groups separately in p+p collisions while one set appears to fit all spectra in central Au+Au collisions.

  6. Blast-wave density measurements

    Microsoft Academic Search

    D. V. Ritzel

    1986-01-01

    Applications of a densitometer to obtain time-resolved data on the total density in blast-wave flows are described. A beta-source (promethium-147) is separated by a gap from a scintillator and a photomultiplier tube (PMT). Attenuation of the radiation beam by the passing blast wave is due to the total density in the gap volume during the wave passage. Signal conditioning and

  7. Blast-wave density measurements

    NASA Astrophysics Data System (ADS)

    Ritzel, D. V.

    Applications of a densitometer to obtain time-resolved data on the total density in blast-wave flows are described. A beta-source (promethium-147) is separated by a gap from a scintillator and a photomultiplier tube (PMT). Attenuation of the radiation beam by the passing blast wave is due to the total density in the gap volume during the wave passage. Signal conditioning and filtering methods permit the system to output linearized data. Results are provided from use of the system to monitor blast waves emitted by detonation of a 10.7 m diameter fiberglass sphere containing 609 tons of ammonium nitrate/fuel oil at a 50.6 m height. Blast wave density data are provided for peak overpressure levels of 245, 172 and 70 kPa and distances of 183, 201 and 314 m from ground zero. Data resolution was of high enough quality to encourage efforts to discriminate dust and gasdynamic phenomena within passing blast waves.

  8. Laboratory blast wave driven instabilities

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn

    2008-11-01

    This presentation discusses experiments involving the evolution of hydrodynamic instabilities in the laboratory under high-energy-density (HED) conditions. These instabilities are driven by blast waves, which occur following a sudden, finite release of energy, and consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. Instabilities evolving under HED conditions are relevant to astrophysics. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 ?m plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses an interface having a 2D or 3D sinusoidal structure that serves as a seed perturbation for hydrodynamic instabilities. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability in the nonlinear regime. We have detected the interface structure under these conditions using x-ray backlighting. Recent advances in our diagnostic techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed or predicted by current simulations. The observed effect is potentially of great importance as a source of mass transport to places not anticipated by current theory and simulation. I will discuss the amount of mass in these spike extensions, the associated uncertainties, and hypotheses regarding their origin We also plan to show comparisons of experiments using single mode and multimode as well as 2D and 3D initial conditions. This work is sponsored by DOE/NNSA Research Grants DE-FG52-07NA28058 (Stewardship Sciences Academic Alliances) and DE-FG52-04NA00064 (National Laser User Facility).

  9. Blast wave reflection from lightly destructible wall

    Microsoft Academic Search

    V. V. Golub; T. V. Bazhenova; O. A. Mirova; Y. L. Sharov; V. V. Volodin

    The paper presents the results of experimental study of the action of blast waves on the obstacle made of different materials.\\u000a The pressure in the front of reflected blast wave is compared in the cases of its interaction with a rigid metal wall and\\u000a the destructible wall made of weakly cemented sand.

  10. On the Propagation and Interaction of Spherical Blast Waves

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Freeman, Robert

    2007-01-01

    The characteristics and the scaling laws of isolated spherical blast waves have been briefly reviewed. Both self-similar solutions and numerical solutions of isolated blast waves are discussed. Blast profiles in the near-field (strong shock region) and the far-field (weak shock region) are examined. Particular attention is directed at the blast overpressure and shock propagating speed. Consideration is also given to the interaction of spherical blast waves. Test data for the propagation and interaction of spherical blast waves emanating from explosives placed in the vicinity of a solid propellant stack are presented. These data are discussed with regard to the scaling laws concerning the decay of blast overpressure.

  11. Blast wave transmission along rough-walled tunnels

    Microsoft Academic Search

    P. D. Smith; P. Vismeg; L. C. Teo; L. Tingey

    1998-01-01

    There is a sizeable body of published work relating to the transmission of blast waves along smooth tunnels of both simple and complex geometry though relatively little has been presented on the propagation of blast waves along tunnels with roughened walls. This paper presents the results of experimental studies carried out at small scale into the propagation of blast waves

  12. Computation of blast wave-obstacle interactions

    NASA Technical Reports Server (NTRS)

    Champney, J. M.; Chaussee, D. S.; Kutler, P.

    1982-01-01

    Numerical simulations of the interaction of a planar blast wave with various obstacles are presented. These obstacles are either ground structures or vehicles flying in the atmosphere. For a structure on the ground, the blast wave encounter is side-on, while for the flying vehicles the encounter is either head-on or oblique. Second-order accurate, finite-difference, and shock-capturing procedures are employed to solve the two-dimensional, axisymmetric, and three-dimensional unsteady Euler equations. Results are presented for the flow field consisting of blast wave striking obstacles that are at rest, moving subsonically and moving supersonically. Comparison of the numerical results with experimental data for a configuration at rest substantiates the validity of this approach and its potential as a flow analysis tool.

  13. The blast wave mitigation effects of a magnetogasdynamic decelerator

    SciTech Connect

    Baty, Roy S [Los Alamos National Laboratory; Lundgren, Ronald G [APPLIED RESEARCH ASSOCIATES; Tucker, Don H [UNIV OF UTAH

    2009-01-01

    This work computes shock wave jump functions for viscous blast waves propagating in a magnetogasdynamic decelerator. The decelerator is assumed to be a one-dimensional channel with sides that are perfect conductors. An electric field applied on the walls of the channel produces a magnetogasdynamic pump, which decelerates the flow field induced by a blast wave. The blast wave jump functions computed here are compared to magnetogasdynamic results for steady supersonic channel flow to quantify potential blast mitigation effects. Theoretical shock wave jump functions are also presented for inviscid blast waves propagating in a one-dimensional channel with an electromagnetic field.

  14. Blast waves and how they interact with structures.

    PubMed

    Cullis, I G

    2001-02-01

    The paper defines and describes blast waves, their interaction with a structure and its subsequent response. Explosions generate blast waves, which need not be due to explosives. A blast wave consists of two parts: a shock wave and a blast wind. The paper explains how shock waves are formed and their basic properties. The physics of blast waves is non-linear and therefore non-intuitive. To understand how an explosion generates a blast wave a numerical modelling computer code, called a hydrocode has to be employed. This is briefly explained and the cAst Eulerian hydrocode is used to illustrate the formation and propagation of the blast wave generated by a 1 kg sphere of TNT explosive detonated 1 m above the ground. The paper concludes with a discussion of the response of a structure to a blast wave and shows that this response is governed by the structures natural frequency of vibration compared to the duration of the blast wave. The basic concepts introduced are illustrated in a second simulation that introduces two structures into the blast field of the TNT charge. PMID:11307674

  15. Biologic response to complex blast waves

    SciTech Connect

    Richmond, D.R.; Yelverton, J.T.; Fletcher, E.R.; Phillips, Y.Y.

    1985-01-01

    Small, bare charges were detonated inside an M59 armored personnel carrier (APC) in an attempt to simulate the complex blast waves generated by the jets from shaped-charge warheads penetrating into armored vehicles. Anesthetized sheep were placed inside the APC at 92- and 122-cm ranges from 57- or 113-g pentolite charges. Pressure-time was measured by pressure transducers either mounted on the animals or free standing at comparable ranges on the opposite side of the vehicle. In general, the waveforms were characterized by an initial shock wave of less than 1-msec duration followed by repeated reflections of decreasing magnitude. No deaths nor lung hemorrhages were observed, but all the animals sustained severe ear injury. Animals subjected to peak overpressures of 1.2 to 2.3 bar from the 113-g explosions also received slight non-auditory blast injuries to the upper respiratory and gastrointestinal tracts; those exposed to peak overpressures of just under 1 bar from the 57-g charges did not. The non-auditory blast injuries inside the APC were more severe than those sustained by sheep at comparable distances from 113-g charges in the open. The results suggested that the biological consequences of a complex wave of the type encountered in this study can be equated approximately to a Friedlander wave with a peak overpressure equal to that of the complex wave and with a total impulse equal to the impulse over the first 2 to 3 msec of the complex wave. 9 refs., 7 figs., 1 tab.

  16. Significance of blast wave studies to propulsion.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.

    1971-01-01

    Brief survey of experimental methods currently used for the study of blast wave phenomena with emphasis on high rate exothermic processes. The experimental techniques have used such devices as divergent test sections in shock or detonation tubes, employment of proper test gases, as in marginal detonations, and a variety of explosion systems from finite source explosion apparatus to devices where virtually point explosions are obtained by local breakdown initiated by means of focused laser irradiation. Other methods used are detonation tubes where pressure waves are generated by accelerating flames or by exothermic reactions developed behind reflected shocks, as well as a variety of converging shock and implosion vessels.

  17. Cylindrical blast wave propagation in an enclosure

    NASA Astrophysics Data System (ADS)

    Bagabir, A. M.

    2012-11-01

    A numerical study of propagation and interaction of cylindrical blast waves in an enclosure at different blast intensities is presented. The interest to study such flows stems from the need to bring in an updated description of the flow field and to predict the pressure loads on the structure. An implicit-unfactored high-resolution hybrid Riemann solver for the two-dimensional Euler equations is used. The characteristic values at the cell faces are evaluated by a modified MUSCL scheme. Numerical schlieren-type images are used for understanding the flows qualitatively. The investigation indicated that the resulting flow field is dominated by complex interacting shock systems due to the complex series of shock focusing events, shock-structure and shock-shock interactions. The pressure-load distribution and maximum overpressure are estimated.

  18. Blast waves generated by planar detonations

    NASA Astrophysics Data System (ADS)

    Thibault, P. A.; Penrose, J. D.; Shepherd, J. E.; Benedick, W. B.; Ritzel, D. V.

    This paper presents experimental and theoretical studies of blast waves generated by gaseous and HE detonations in long cylindrical tubes. The experimental studies were performed using the 1.8 m diameter shock tube facilities at the Defence Research Establishment Suffield and at the New Mexico Engineering Research Institute. Two gaseous explosives, acetylene-oxygen and hydrogen-air, and one solid explosive, 120g nitroguanidine, were used in order to verify the validity of energy scaling in the far-field. The above experimental work is supported by one- and two-dimensional numerical computations which are based on the Flux Corrected Transport (FCT) algorithm. The experimental results are also analyzed in terms of a simple analytical blast model.

  19. Studies of laser-driven radiative blast waves

    SciTech Connect

    Edwards, M J; Hansen, J; Edens, A; Ditmire, T; Adams, R; Rambo, P; Ruggles, L; Smith, I; Porter, J

    2004-04-29

    We have performed two sets of experiments looking at laser-driven radiating blast waves. In one set of experiments the effect of a drive laser's passage through a background gas on the hydrodynamical evolution of blast waves was examined. It was found that the laser's passage heats a channel in the gas, creating a region where a portion of the blast wave front had an increased velocity, leading to the formation of a bump-like protrusion on the blast wave. The second set of experiments involved the use of regularly spaced wire arrays to induce perturbations on a blast wave surface. The decay of these perturbations as a function of time was measured for various wave number perturbations and found to be in good agreement with theoretical predictions.

  20. The Relativistic Wave Vector

    ERIC Educational Resources Information Center

    Houlrik, Jens Madsen

    2009-01-01

    The Lorentz transformation applies directly to the kinematics of moving particles viewed as geometric points. Wave propagation, on the other hand, involves moving planes which are extended objects defined by simultaneity. By treating a plane wave as a geometric object moving at the phase velocity, novel results are obtained that illustrate the…

  1. Adiabatic Losses and Stochastic Particle Acceleration in Gamma-Ray Burst Blast Waves

    E-print Network

    Charles D. Dermer; Mayer Humi

    2001-03-26

    We treat the problem of adiabatic losses and stochastic particle acceleration in gamma-ray burst (GRB) blast waves that decelerate by sweeping up matter from an external medium. The shocked fluid is assumed to be represented by a homogeneous expanding shell. The energy lost by nonthermal particles through adiabatic expansion is converted to the bulk kinetic energy of the outflow, permitting the evolution of the bulk Lorentz factor Gamma of the blast wave to be self-consistently calculated. The behavior of the system is shown to reproduce the hydrodynamic self-similar solutions in the relativistic and nonrelativistic limits, and the formalism is applicable to scenarios that are intermediate between the adiabatic and fully radiative regimes. Nonthermal particle energization through stochastic gyroresonant acceleration with magnetic turbulence in the blast wave is treated by employing energy-gain rates and diffusive escape timescales based upon expressions derived in the quasilinear regime. If the magnetic field in the shocked fluid approaches its equipartition value, this process can accelerate escaping particles to >~10^{20} eV energies, consistent with the hypothesis that ultra-high energy cosmic rays (UHECRs) are accelerated by GRB blast waves. Due to particle trapping by the magnetic turbulence, only the highest energy particles can escape during the prompt and afterglow phases of a GRB for acceleration by a Kolmogorov spectrum of MHD turbulence. Lower energy particles begin to escape as the blast wave becomes nonrelativistic and shock Fermi acceleration becomes more important.

  2. On the Interaction and Coalescence if Spherical Blast Waves

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Freeman, Robert J.

    2005-01-01

    The scaling and similarity laws concerning the propagation of isolated spherical blast waves are briefly reviewed. Both point source explosions and high pressure gas explosions are considered. Test data on blast overpressure from the interaction and coalescence of spherical blast waves emanating from explosives in the form of shaped charges of different strength placed in the vicinity of a solid propellant stack are presented. These data are discussed with regard to the scaling laws concerning the decay of blast overpressure. The results point out the possibility of detecting source explosions from far-field pressure measurements.

  3. Percolation of Blast Waves though Sand

    NASA Astrophysics Data System (ADS)

    Proud, William

    2013-06-01

    Previous research has concentrated on the physical processes occurring when samples of sand, of varying moisture content, were shock compressed. In this study quartz sand samples are subjected to blast waves over a range of pressure and duration. Aspects of particle movement are discussed; the global movement of a bed hundreds of particles thick is a fraction of particle width. The main diagnostics used are pressure sensors and high-speed photography. Results are presented for a range of particle sizes, aspect ratio, density and moisture content. While the velocity of the percolation through the bed is primarily controlled by density and porosity the effect of moisture reveals a more complex dependence. Previous research has concentrated on the physical processes occurring when samples of sand, of varying moisture content, were shock compressed. In this study quartz sand samples are subjected to blast waves over a range of pressure and duration. Aspects of particle movement are discussed; the global movement of a bed hundreds of particles thick is a fraction of particle width. The main diagnostics used are pressure sensors and high-speed photography. Results are presented for a range of particle sizes, aspect ratio, density and moisture content. While the velocity of the percolation through the bed is primarily controlled by density and porosity the effect of moisture reveals a more complex dependence. The ISP acknowledges the support of the Atomic Weapons Establishment and Imperial College London.

  4. Evolution of blast wave profiles in simulated air blasts: experiment and computational modeling

    NASA Astrophysics Data System (ADS)

    Chandra, N.; Ganpule, S.; Kleinschmit, N. N.; Feng, R.; Holmberg, A. D.; Sundaramurthy, A.; Selvan, V.; Alai, A.

    2012-09-01

    Shock tubes have been extensively used in the study of blast traumatic brain injury due to increased incidence of blast-induced neurotrauma in Iraq and Afghanistan conflicts. One of the important aspects in these studies is how to best replicate the field conditions in the laboratory which relies on reproducing blast wave profiles. Evolution of the blast wave profiles along the length of the compression-driven air shock tube is studied using experiments and numerical simulations with emphasis on the shape and magnitude of pressure time profiles. In order to measure dynamic pressures of the blast, a series of sensors are mounted on a cylindrical specimen normal to the flow direction. Our results indicate that the blast wave loading is significantly different for locations inside and outside of the shock tube. Pressure profiles inside the shock tube follow the Friedlander waveform fairly well. Upon approaching exit of the shock tube, an expansion wave released from the shock tube edges significantly degrades the pressure profiles. For tests outside the shock tube, peak pressure and total impulse reduce drastically as we move away from the exit and majority of loading is in the form of subsonic jet wind. In addition, the planarity of the blast wave degrades as blast wave evolves three dimensionally. Numerical results visually and quantitatively confirm the presence of vortices, jet wind and three-dimensional expansion of the planar blast wave near the exit. Pressure profiles at 90° orientation show flow separation. When cylinder is placed inside, this flow separation is not sustained, but when placed outside the shock tube this flow separation is sustained which causes tensile loading on the sides of the cylinder. Friedlander waves formed due to field explosives in the intermediate-to far-field ranges are replicated in a narrow test region located deep inside the shock tube.

  5. A Thoracic Mechanism of Mild Traumatic Brain Injury Due to Blast Pressure Waves

    Microsoft Academic Search

    Amy Courtney; Michael Courtney

    2008-01-01

    The mechanisms by which blast pressure waves cause mild to moderate traumatic brain injury (mTBI) are an open question. Possibilities include acceleration of the head, direct passage of the blast wave via the cranium, and propagation of the blast wave to the brain via a thoracic mechanism. The hypothesis that the blast pressure wave reaches the brain via a thoracic

  6. Device for Underwater Laboratory Simulation of Unconfined Blast Waves

    E-print Network

    Courtney, Elijah; Courtney, Michael

    2015-01-01

    Shock tubes simulate blast waves to study their effects in air under laboratory conditions; however, few experimental models exist for simulating underwater blast waves that are needed for facilitating experiments in underwater blast transmission, determining injury thresholds in marine animals, validating numerical models, and exploring mitigation strategies for explosive well removals. This method incorporates an oxy-acetylene driven underwater blast simulator which creates peak blast pressures of about 1860 kPa. Shot-to-shot consistency was fair, with an average standard deviation near 150 kPa. Results suggest peak blast pressures from 460 kPa to 1860 kPa are available by adjusting the distance from the source.

  7. Note: Device for underwater laboratory simulation of unconfined blast waves

    NASA Astrophysics Data System (ADS)

    Courtney, Elijah; Courtney, Amy; Courtney, Michael

    2015-06-01

    Shock tubes simulate blast waves to study their effects in air under laboratory conditions; however, few experimental models exist for simulating underwater blast waves that are needed for facilitating experiments in underwater blast transmission, determining injury thresholds in marine animals, validating numerical models, and exploring mitigation strategies for explosive well removals. This method incorporates an oxy-acetylene driven underwater blast simulator which creates peak blast pressures of about 1860 kPa. Shot-to-shot consistency was fair, with an average standard deviation near 150 kPa. Results suggest that peak blast pressures from 460 kPa to 1860 kPa are available by adjusting the distance from the source.

  8. Ponderomotive acceleration by relativistic waves

    NASA Astrophysics Data System (ADS)

    Lau, C. K.; Yeh, P. C.; Luk, O.; McClenaghan, J.; Ebisuzaki, T.; Tajima, T.

    2015-02-01

    In the extreme high intensity regime of electromagnetic (EM) waves in plasma, the acceleration process is found to be dominated by the ponderomotive acceleration (PA). While the wakefields driven by the ponderomotive force of the relativistic intensity EM waves are important, they may be overtaken by the PA itself in the extreme high intensity regime when the dimensionless vector potential a0 of the EM waves far exceeds unity. The energy gain by this regime (in 1D) is shown to be (approximately) proportional to a0 2 . Before reaching this extreme regime, the coexistence of the PA and the wakefield acceleration is observed where the wave structures driven by the wakefields show the phenomenon of multiple and folded wave breakings. Investigated are various signatures of the acceleration processes such as the dependence on the mass ratio for the energy gain as well as the energy spectral features. The relevance to high energy cosmic ray acceleration and to the relativistic laser acceleration is considered.

  9. Investigation of Ultrafast Laser-Driven Radiative Blast Waves

    Microsoft Academic Search

    M. J. Edwards; A. J. MacKinnon; J. Zweiback; K. Shigemori; D. Ryutov; A. M. Rubenchik; K. A. Keilty; E. Liang; B. A. Remington; T. Ditmire

    2001-01-01

    We have examined the evolution of cylindrically symmetric blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high- Z gases radiative effects become important. We observe the production of an ionization precursor ahead of the shock front and deceleration parameters below the adiabatic value of 1\\/2 (for a cylinder), an effect expected when the blast

  10. Reactive Blast Waves from Composite Charges

    SciTech Connect

    Kuhl, A L; Bell, J B; Beckner, V E

    2009-10-16

    Investigated here is the performance of composite explosives - measured in terms of the blast wave they drive into the surrounding environment. The composite charge configuration studied here was a spherical booster (1/3 charge mass), surrounded by aluminum (Al) powder (2/3 charge mass) at an initial density of {rho}{sub 0} = 0.604 g/cc. The Al powder acts as a fuel but does not detonate - thereby providing an extreme example of a 'non-ideal' explosive (where 2/3 of the charge does not detonate). Detonation of the booster charge creates a blast wave that disperses the Al powder and ignites the ensuing Al-air mixture - thereby forming a two-phase combustion cloud embedded in the explosion. Afterburning of the booster detonation products with air also enhances and promotes the Al-air combustion process. Pressure waves from such reactive blast waves have been measured in bomb calorimeter experiments. Here we describe numerical simulations of those experiments. A Heterogeneous Continuum Model was used to model the dispersion and combustion of the Al particle cloud. It combines the gasdynamic conservation laws for the gas phase with a dilute continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models of Khasainov. It incorporates a combustion model based on mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Adaptive Mesh Refinement (AMR) was used to capture the energy-bearing scales of the turbulent flow on the computational grid, and to track/resolve reaction zones. Numerical simulations of the explosion fields from 1.5-g and 10-kg composite charges were performed. Computed pressure histories (red curve) are compared with measured waveforms (black curves) in Fig. 1. Comparison of these results with a waveform for a non-combustion case in nitrogen (blue curve) demonstrates that a reactive blast wave was formed. Cross-sectional views of the temperature field at various times are presented in Fig. 2, which shows that the flow is turbulent. Initially, combustion occurs at the fuel-air interface, and the energy release rate is controlled by the rate of turbulent mixing. Eventually, oxidizer becomes distributed throughout the cloud via ballistic mixing of the particles with air; energy release then occurs in a distributed combustion mode, and Al particle kinetics controls the energy release rate. Details of the Heterogeneous Continuum Model and results of the numerical simulations of composite charge explosions will be described in the paper.

  11. Investigation of ultrafast laser-driven radiative blast waves.

    PubMed

    Edwards, M J; MacKinnon, A J; Zweiback, J; Shigemori, K; Ryutov, D; Rubenchik, A M; Keilty, K A; Liang, E; Remington, B A; Ditmire, T

    2001-08-20

    We have examined the evolution of cylindrically symmetric blast waves produced by the deposition of femtosecond laser pulses in gas jets. In high- Z gases radiative effects become important. We observe the production of an ionization precursor ahead of the shock front and deceleration parameters below the adiabatic value of 1/2 (for a cylinder), an effect expected when the blast wave loses energy by radiative cooling. Despite significant radiative cooling, the blast waves do not appear to develop thin shell instabilities expected for strongly radiative waves. This is believed to be due to the stabilizing effect of a relatively thick blast wave shell resulting in part from electron thermal conduction effects. PMID:11497951

  12. Langmuir wave in weakly inhomogeneous relativistic plasma

    SciTech Connect

    Matveev, A. I. [South Federal University, Institute of Technology (Russian Federation)

    2008-11-15

    The evolution of a Langmuir wave in a weakly inhomogeneous relativistic plasma with a positive density gradient is considered. It is shown that, at relativistic phase velocities, the wave evolution even at the tail of the electron distribution, where it is close to linear in the nonrelativistic case, results in the wave transformation into a hybrid of two waves with different spatial periods. Nonlinear dispersion relations for different stages of the wave evolution are derived.

  13. Simple waves in relativistic fluids

    SciTech Connect

    Lyutikov, Maxim [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, Indiana 47907-2036 (United States)

    2010-11-15

    We consider the Riemann problem for relativistic flows of polytropic fluids and find relations for the flow characteristics. Evolution of physical quantities takes especially simple form for the case of cold magnetized plasmas. We find exact explicit analytical solutions for one-dimensional expansion of magnetized plasma into vacuum, valid for arbitrary magnetization. We also consider expansion into cold unmagnetized external medium both for stationary initial conditions and for initially moving plasma, as well as reflection of rarefaction wave from a wall. We also find self-similar structure of three-dimensional magnetized outflows into vacuum, valid close to the plasma-vacuum interface.

  14. NO FLARES FROM GAMMA-RAY BURST AFTERGLOW BLAST WAVES ENCOUNTERING SUDDEN CIRCUMBURST DENSITY CHANGE

    SciTech Connect

    Gat, Ilana; Van Eerten, Hendrik; MacFadyen, Andrew [Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003 (United States)

    2013-08-10

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

  15. No Flares from Gamma-Ray Burst Afterglow Blast Waves Encountering Sudden Circumburst Density Change

    NASA Astrophysics Data System (ADS)

    Gat, Ilana; van Eerten, Hendrik; MacFadyen, Andrew

    2013-08-01

    Afterglows of gamma-ray bursts are observed to produce light curves with the flux following power-law evolution in time. However, recent observations reveal bright flares at times on the order of minutes to days. One proposed explanation for these flares is the interaction of a relativistic blast wave with a circumburst density transition. In this paper, we model this type of interaction computationally in one and two dimensions, using a relativistic hydrodynamics code with adaptive mesh refinement called RAM, and analytically in one dimension. We simulate a blast wave traveling in a stellar wind environment that encounters a sudden change in density, followed by a homogeneous medium, and compute the observed radiation using a synchrotron model. We show that flares are not observable for an encounter with a sudden density increase, such as a wind termination shock, nor for an encounter with a sudden density decrease. Furthermore, by extending our analysis to two dimensions, we are able to resolve the spreading, collimation, and edge effects of the blast wave as it encounters the change in circumburst medium. In all cases considered in this paper, we find that a flare will not be observed for any of the density changes studied.

  16. Measurement of Blast Waves from Bursting Pressureized Frangible Spheres

    NASA Technical Reports Server (NTRS)

    Esparza, E. D.; Baker, W. E.

    1977-01-01

    Small-scale experiments were conducted to obtain data on incident overpressure at various distances from bursting pressurized spheres. Complete time histories of blast overpressure generated by rupturing glass spheres under high internal pressure were obtained using eight side-on pressure transducers. A scaling law is presented, and its nondimensional parameters are used to compare peak overpressures, arrival times, impulses, and durations for different initial conditions and sizes of blast source. The nondimensional data are also compared, whenever possible, with results of theoretical calculations and compiled data for Pentolite high explosive. The scaled data are repeatable and show significant differences from blast waves generated by condensed high-explosives.

  17. Spectroscopic diagnostics in a colliding-blast-wave experiment

    NASA Astrophysics Data System (ADS)

    Elton, R. C.; Billings, D.-M.; Manka, C. K.; Griem, H. R.; Grun, J.; Ripin, B. H.; Resnick, J.

    1994-02-01

    Visible spectral lines from n=3, ?n=0 transitions in N+ and N2+ ions are used for measuring the plasma electron density and temperature in a region of two colliding blast waves, propagating through a 1.5-10-Torr nitrogen atmosphere. The blast waves originate at the tips of two aluminum rods irradiated with two beams of the Naval Research Laboratory (NRL) Pharos-III 1.054-?m-wavelength Nd:glass laser operated at an energy of 200-430 J for each beam in 5-ns pulses. An electron density in the colliding-blast-wave region of Ne~=1018 cm-3 was deduced from Stark broadening of spectral lines from N+ ions. An electron temperature of Te~=4 eV was measured in this region from a spectral-line intensity ratio between N2+ and N+ ions. Near one target, an electron density of Ne~=8×1020 cm-3 was determined from series-limit x-ray spectral-line merging; a mean electron temperature of kTe~=225 eV was determined from x-ray line-intensity ratios. Some evidence was found for enhanced velocities for blast waves propagating through a plasma formed by a preceding blast wave.

  18. 3D Tomographic imaging of colliding cylindrical blast waves

    NASA Astrophysics Data System (ADS)

    Smith, R. A.; Lazarus, J.; Hohenberger, M.; Robinson, J.; Marocchino, A.; Chittenden, J.; Dunne, M.; Moore, A.; Gumbrell, E.

    2007-11-01

    The interaction of strong shocks & radiative blast waves is believed to give rise to the turbulent, knotted structures commonly observed in extended astrophysical objects. Modeling these systems is however extremely challenging due to the complex interplay between hydrodynamics, radiation and atomic physics. As a result we have been developing laboratory scale blast wave collision experiments to provide high quality data for code benchmarking, & to improve our physical understanding. We report on experimental & numerical investigations of the collision dynamics of counter propagating strong (>Mach 50) cylindrical thin-shelled blast waves driven by focusing intense laser pulses into an extended medium of atomic clusters. In our test system the blast wave collision creates strongly asymmetric electron density profiles, precluding the use of Abel inversion methods. In consequence we have employed a new tomographic imaging technique, allowing us to recover the full 3D, time framed electron density distribution. Tomography & streaked Schlieren imaging enabled tracking of radial & longitudinal mass flow & the investigation of Mach stem formation as pairs of blast waves collided. We have compared our experimental system to numerical simulations by the 3D magnetoresistive hydrocode GORGON.

  19. Femtosecond laser energy deposition in strongly absorbing cluster gases diagnosed by blast wave trajectory analysis

    E-print Network

    Ditmire, Todd

    Femtosecond laser energy deposition in strongly absorbing cluster gases diagnosed by blast wave cylindrically symmetric blast waves. Using the well-known relation between blast wave velocity and energy of atomic and molecular clusters. These studies have been motivated by the possibility of using a cluster

  20. Spectroscopic diagnostics in a colliding-blast-wave experiment

    SciTech Connect

    Elton, R.C.; Billings, D.; Manka, C.K.; Griem, H.R.; Grun, J.; Ripin, B.H. (Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375 (United States)); Resnick, J. (Research Support Instruments, Inc., Alexandria, Virginia 22314 (United States))

    1994-02-01

    Visible spectral lines from [ital n]=3, [Delta][ital n]=0 transitions in N[sup +] and N[sup 2+] ions are used for measuring the plasma electron density and temperature in a region of two colliding blast waves, propagating through a 1.5--10-Torr nitrogen atmosphere. The blast waves originate at the tips of two aluminum rods irradiated with two beams of the Naval Research Laboratory (NRL) Pharos-III 1.054-[mu]m-wavelength Nd:glass laser operated at an energy of 200--430 J for each beam in 5-ns pulses. An electron density in the colliding-blast-wave region of [ital N][sub [ital e

  1. Quick reproduction of blast-wave flow-field properties of nuclear, TNT, and ANFO explosions

    Microsoft Academic Search

    C. P. T. Groth

    1986-01-01

    In many instances, extensive blast-wave flow-field properties are required in gasdynamics research studies of blast-wave loading and structure response, and in evaluating the effects of explosions on their environment. This report provides a very useful computer code, which can be used in conjunction with the DNA Nuclear Blast Standard subroutines and code, to quickly reconstruct complete and fairly accurate blast-wave

  2. Relativistic electron acceleration by oblique whistler waves

    SciTech Connect

    Yoon, Peter H. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States) [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Pandey, Vinay S. [National Institute of Technology Delhi, Dwarka, Delhi—110077 (India)] [National Institute of Technology Delhi, Dwarka, Delhi—110077 (India); Lee, Dong-Hun [School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of)] [School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of)

    2013-11-15

    Test-particle simulations of electrons interacting with finite-amplitude, obliquely propagating whistler waves are carried out in order to investigate the acceleration of relativistic electrons by these waves. According to the present findings, an efficient acceleration of relativistic electrons requires a narrow range of oblique propagation angles, close to the whistler resonance cone angle, when the wave amplitude is held constant at relatively low value. For a constant wave propagation angle, it is found that a range of oblique whistler wave amplitudes permits the acceleration of relativistic electrons to O(MeV) energies. An initial distribution of test electrons is shown to form a power-law distribution when plotted in energy space. It is also found that the acceleration is largely uniform in electron pitch-angle space.

  3. Simulation of blast-induced, early-time intracranial wave physics leading to traumatic brain injury.

    SciTech Connect

    Taylor, Paul Allen; Ford, Corey C. (University of New Mexico, Albuquerque, NM)

    2008-04-01

    U.S. soldiers are surviving blast and impacts due to effective body armor, trauma evacuation and care. Blast injuries are the leading cause of traumatic brain injury (TBI) in military personnel returning from combat. Understanding of Primary Blast Injury may be needed to develop better means of blast mitigation strategies. The objective of this paper is to investigate the effects of blast direction and strength on the resulting mechanical stress and wave energy distributions generated in the brain.

  4. Measurements of strong blast waves in gas targets

    Microsoft Academic Search

    K. Shigemori; T. Ditmire; T. Kuehl; B. A. Remington; A. M. Rubenchik; K. A. Keilty

    1998-01-01

    The propagation of blast waves is of fundamental importance in determining the structure of the interstellar medium. To develop a laboratory testbed for astrophysically relevant shock physics, we have started an experiment using a high intensity, short pulse laser and a gas jet target. Gas targets of Ar, Ne, Xe at ion densities of 10^19 cm-3 are irradiated with a

  5. A systematic exposition of the conservation equations for blast waves.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.; Lundstrom, E. A.; Kuhl, A. L.; Kamel, M. M.

    1971-01-01

    In order to provide a rational background for the analysis of experimental observations of blast wave phenomena, the conservation equations governing their nonsteady flow field are formulated in a general manner, without the usual restrictions imposed by an equation of state, and with proper account taken, by means of source terms, of other effects which, besides the inertial terms that conventionally dominate these equations, can affect the flow. Taking advantage of the fact that a blast wave can be generally considered as a spatially one-dimensional flow field whose nonsteady behavior can be regarded, consequently, as a function of just two independent variables, two generalized blast wave coordinates are introduced, one associated with the front of the blast wave and the other with its flow field. The conservation equations are accordingly transformed into this coordinate system, acquiring thereby a comprehensive character, in that they refer then to any frame of reference, being applicable, in particular, to problems involving either space or time profiles of the gas-dynamic parameters in the Eulerian system, or time profiles in the Lagrangian system.

  6. Blast wave attenuation by lightly destructable granular materials

    E-print Network

    Texas at Arlington, University of

    is to coat the surface with a sacrificial layer. In [3] full-scale experiments were carried out to investigate the behaviour of a covering of aluminum foam under the effect of a blast wave. In our study steel chamber V BK - 2, 4.5m in diameter and 7m in length. The sand/cement cylinder was placed 95cm

  7. On the method of phase space for blast waves

    Microsoft Academic Search

    A. K. Oppenheim; A. L. Kuhl; M. M. Kamel

    1978-01-01

    A new analytical approach to general blast wave problems is described that makes essential use of the existence of singularities. The method is based on a three-dimensional phase space, by means of which the solution is reduced to the task of determining an integral surface or family of integral lines in a space defined in terms of appropriate reduced coordinates

  8. Blast waves in atomic cluster media using intense laser pulses

    Microsoft Academic Search

    Roland Smith

    2008-01-01

    We report on the progress of experimental and numerical investigations of the dynamics of strong (>Mach 50) blast waves driven by focusing sub-ps laser pulses into an extended medium of atomic clusters. A gas of atomic clusters is an extraordinarily efficient absorber of intense laser light and can be used to create high energy density plasmas with tabletop laser systems.

  9. Relativistic Hydromagnetic Waves and Group Velocity

    Microsoft Academic Search

    Albert C. Giere

    1966-01-01

    The velocities of relativistic hydromagnetic waves in a compressible, perfect fluid of infinite conductivity are calculated in the framework of general relativity. In the absence of viscuous and Joule heat losses, the flow is isentropic, and, therefore, the wave surfaces are propagated without change of shape. The velocities are first obtained in terms of the four-vector magnetic field and then

  10. Weakly relativistic dispersion of Bernstein waves

    NASA Technical Reports Server (NTRS)

    Robinson, P. A.

    1988-01-01

    Weakly relativistic effects on the dispersion of Bernstein waves are investigated for waves propagating nearly perpendicular to a uniform magnetic field in a Maxwellian plasma. Attention is focused on those large-wave-vector branches that are either weakly damped or join continuously onto weakly damped branches since these are the modes of most interest in applications. The transition between dispersion at perpendicular and oblique propagation is examined and major weakly relativistic effects can dominate even in low-temperature plasmas. A number of simple analytic criteria are obtained which delimit the ranges of harmonic number and propagation angle within which various types of weakly damped Bernstein modes can exist.

  11. Blast waves in atomic cluster media using intense laser pulses.

    NASA Astrophysics Data System (ADS)

    Smith, Roland

    2008-04-01

    We report on the progress of experimental and numerical investigations of the dynamics of strong (>Mach 50) blast waves driven by focusing sub-ps laser pulses into an extended medium of atomic clusters. A gas of atomic clusters is an extraordinarily efficient absorber of intense laser light and can be used to create high energy density plasmas with tabletop laser systems. These HED plasmas can launch shocks and strongly radiative blast waves with dimensionless parameters scalable to astrophysical objects such as supernova remnants, and have been used by us in a number of shock evolution and collision studies. To date such experiments have been conducted with modest laser energies of <1J. In order to study processes such as the Vishniac overstability and cooling instability in these systems significantly more input energy may be required due to the weak variation of blast wave velocity with deposited energy Vb E^1/4. We report on the scaling of cluster blast wave experiments to laser energies up 0.5kJ using the Vulcan laser at RAL. An extensive suite of diagnostics including multi-frame optical probe systems, streaked Schlieren imaging and keV imaging and spectroscopy was fielded in order to study the growth of spatial and temporal instabilities. To better match astrophysical scenarios with strong radiative pre-heat of material upstream of the shock an additional radiation field was also introduced using a secondary laser heated gold foil target and grazing incidence XUV guiding structure. This allowed us to compare blast wave propagation into cold versus hot ionized upstream gases. These experimental systems provide a useful test bed against which to benchmark numerical simulations, and have been compared to the 3D magnetoresistive hydrocode GORGON and radiation-hydrodynamics code NYM.

  12. Blast wave reflection trajectories from a height of burst

    Microsoft Academic Search

    T. C. J. Hu; I. I. Glass

    1986-01-01

    Consideration is given to an explosive charge (TNT) detonated at various heights of burst above a perfect reflecting planar surface in air. Variations of the incident shock Mach number M(s) of the spherical blast wave front as it decays, and the corresponding wedge angle theta(w), are plotted on a two-dimensional shock wave reflection transition map in the M(s), theta(w) plane.

  13. Compact-electron-beam or light-ion-beam fusion reactor cavity design using non-spherical blast waves

    Microsoft Academic Search

    G. A. Moses; R. Spencer

    1979-01-01

    The application of inhomogeneous cavity gas densities and the non-spherical blast wave resulting from an explosion in this gas offers the potential to reduce the distance between the final diode and the target in a relativistic-electron-beam (REB) or light-ion beam (LIB) fusion reactor. It can also sharply reduce the overpressure experienced by the diode after the target explosion.

  14. Relativistically modulational instability by strong Langmuir waves

    SciTech Connect

    Liu, X. L.; Liu, S. Q. [Department of Physics, Nanchang University, Jiangxi, Nanchang 330031 (China); Li, X. Q. [Department of Physics, Nanjing Normal University, Nanjing 210097 (China)

    2012-09-15

    Based on the set of nonlinear coupling equations, which has considered the relativistic effects of electrons, modulational instability by strong Langmuir waves has been investigated in this paper. Both the characteristic scale and maximum growth rate of the Langmuir field will enhance with the increase in the electron relativistic effect. The numerical results indicate that longitudinal perturbations induce greater instability than transverse perturbations do, which will lead to collapse and formation of the pancake-like structure.

  15. Towards a fast-running method for blast-wave mitigation by a prismatic blast wall

    NASA Astrophysics Data System (ADS)

    Éveillard, Sébastien; Lardjane, Nicolas; Vinçont, Jean-Yves; Sochet, Isabelle

    A procedure aimed at developing a fast-running method for blast-wave effects characterization behind a protection barrier is presented. Small-scale experiments of a hemispherical gaseous charge (stoichiometric propane-oxygen mixture) without and with a prismatic protective barrier are used to validate the use of an in-house CFD code for gaseous detonation. From numerical experiments, pressure loss of a blast wave at a corner is quantified. These fits, in conjunction with TM5-1300 reflection charts, are used to estimate the maximum overpressure around a protective barrier through geometrical and empirical laws. The results show good agreement with numerical and experimental data from the ANR-BARPPRO research project.

  16. Blast Wave Driven Instabilities In Laboratory Astrophysics Experiments

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn; Drake, R.; Grosskopf, M.; Robey, H.; Hansen, J.; Miles, A.; Knauer, J.; Arnett, D.; Plewa, T.; Hearn, N.; Meakin, C.

    2008-05-01

    This presentation discusses experiments well scaled to the blast wave driven instabilities at the He/H interface during the explosion phase of SN1987A. This core-collapse supernova was detected about 50 kpc from Earth making it the first supernova observed so closely to earth in modern times. The progenitor star was a blue supergiant with a mass of 18-20 solar masses. A blast wave occurred following the supernova explosion because there was a sudden, finite release of energy. Blast waves consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 µm plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses a three-dimensional interface with a wavelength of 71 µm in two orthogonal directions. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability. We have detected the interface structure under these conditions, using dual orthogonal radiography, and will show some of the resulting data. Recent advancements in our x-ray backlighting techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed. Current simulations do not show this phenomenon. This presentation will discuss the amount of mass in these spike extensions. Recent results from an experiment using more realistic initial conditions based on stellar evolution models will also be shown. This research was sponsored by the Stewardship Science Academic Alliance through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA00064.

  17. A thoracic mechanism of mild traumatic brain injury due to blast pressure waves

    Microsoft Academic Search

    A. C. Courtney; Michael Courtney

    2009-01-01

    The mechanisms by which blast pressure waves cause mild to moderate traumatic\\u000abrain injury (mTBI) are an open question. Possibilities include acceleration of\\u000athe head, direct passage of the blast wave via the cranium, and propagation of\\u000athe blast wave to the brain via a thoracic mechanism. The hypothesis that the\\u000ablast pressure wave reaches the brain via a thoracic

  18. 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.

  19. Blast waves from violent explosive activity at Yasur volcano, Vanuatu

    NASA Astrophysics Data System (ADS)

    Marchetti, E.; Ripepe, M.; Delle Donne, D.; Genco, R.; Finizola, A.; Garaebiti, E.

    2013-12-01

    The violent Strombolian activity at Yasur volcano (Vanuatu) was recorded with infrasonic, seismic and thermal sensors. Infrasound array allowed to identify and stack ~3000 infrasonic and seismic transiensts of explosions from two distinct vents. The stacked seismic signals evidence a low-frequency (0.15 Hz) signal preceding of ~5-6 s the explosion that was hidden by the high seismic tremor and microseism. Infrasonic signals are self-similar presenting a stable strong asymmetry, with a sharp positive pressure (5-106 Pa) onset followed by a longer lasting negative rarefaction phase. Self-similarity and asymmetry of the recorded pressure waveforms are recalling blast waves. Regardless the pressure amplitude, ratio between the positive and negative phase is constant. This fit the Friedland waveform and support the blast wave model. Thermal imagery detects this pressure wave as soon as it exits the vent as a relative ~20 m thick cold front, which radiates spherically from the source. This front of apparent cold temperature is moving before the volcanic hot gas/fragments cloud at a velocity ranging between 342 and 403 m/s. We interpret this cold front as produced by the change of the atmospheric refraction index induced by the passage of the shock front. Assuming a supersonic dynamics, we calculate that the mean acoustic pressure (25 Pa) recorded at the array is generated by a a gas expansion velocity of 372 m/s equivalent to Mach number of 1.1. Our data are then suggesting that explosive activity at Yasur is able to generate blast waves indicating supersonic gas expansion. Blast waves are expected and well documented for Plinian and Vulcanian eruptions, but have never been recorded during Strombolian events. This evidence has a direct consequence on the source modeling of infrasonic transients explosions as it requires non-linear source dynamics to explain also small scale (VEI<2) explosive processes.

  20. Resonant Amplification of Turbulence by the Blast Waves

    NASA Astrophysics Data System (ADS)

    Zankovich, A. M.; Kovalenko, I. G.

    2015-02-01

    We discuss the idea of whether spherical blast waves can amplify by a nonlocal resonant hydrodynamic mechanism inhomogeneities formed by turbulence or phase segregation in the interstellar medium. We consider the problem of a blast-wave-turbulence interaction in the Linear Interaction Approximation. Mathematically, this is an eigenvalue problem for finding the structure and amplitude of eigenfunctions describing the response of the shock-wave flow to forced oscillations by external perturbations in the ambient interstellar medium. Linear analysis shows that the blast wave can amplify density and vorticity perturbations for a wide range of length scales with amplification coefficients of up to 20, with increasing amplification the larger the length. There also exist resonant harmonics for which the gain becomes formally infinite in the linear approximation. Their orbital wavenumbers are within the range of macro- (l ~ 1), meso- (l ~ 20), and microscopic (l > 200) scales. Since the resonance width is narrow (typically, ?l < 1), resonance should select and amplify discrete isolated harmonics. We speculate on a possible explanation of an observed regular filamentary structure of regularly shaped round supernova remnants such as SNR 1572, 1006, or 0509-67.5. Resonant mesoscales found (l ? 18) are surprisingly close to the observed scales (l ? 15) of ripples in the shell's surface of SNR 0509-67.5.

  1. Impact of complex blast waves on the human head: a computational study.

    PubMed

    Tan, Long Bin; Chew, Fatt Siong; Tse, Kwong Ming; Chye Tan, Vincent Beng; Lee, Heow Pueh

    2014-12-01

    Head injuries due to complex blasts are not well examined because of limited published articles on the subject. Previous studies have analyzed head injuries due to impact from a single planar blast wave. Complex or concomitant blasts refer to impacts usually caused by more than a single blast source, whereby the blast waves may impact the head simultaneously or consecutively, depending on the locations and distances of the blast sources from the subject, their blast intensities, the sequence of detonations, as well as the effect of blast wave reflections from rigid walls. It is expected that such scenarios will result in more serious head injuries as compared to impact from a single blast wave due to the larger effective duration of the blast. In this paper, the utilization of a head-helmet model for blast impact analyses in Abaqus(TM) (Dassault Systemes, Singapore) is demonstrated. The model is validated against studies published in the literature. Results show that the skull is capable of transmitting the blast impact to cause high intracranial pressures (ICPs). In addition, the pressure wave from a frontal blast may enter through the sides of the helmet and wrap around the head to result in a second impact at the rear. This study recommended better protection at the sides and rear of the helmet through the use of foam pads so as to reduce wave entry into the helmet. The consecutive frontal blasts scenario resulted in higher ICPs compared with impact from a single frontal blast. This implied that blast impingement from an immediate subsequent pressure wave would increase severity of brain injury. For the unhelmeted head case, a peak ICP of 330?kPa is registered at the parietal lobe which exceeds the 235?kPa threshold for serious head injuries. The concurrent front and side blasts scenario yielded lower ICPs and skull stresses than the consecutive frontal blasts case. It is also revealed that the additional side blast would only significantly affect ICPs at the temporal and parietal lobes when compared with results from the single frontal blast case. By analyzing the pressure wave flow surrounding the head and correlating them with the consequential evolution of ICP and skull stress, the paper provides insights into the interaction mechanics between the concomitant blast waves and the biological head model. PMID:25132676

  2. Vorticity deposition, structure generation and the approach to self-similarity in colliding blast wave experiments

    NASA Astrophysics Data System (ADS)

    Robinson, A. P. L.; Schmitz, H.; Fox, T. E.; Pasley, J.; Symes, D. R.

    2015-03-01

    When strong shocks interact with transverse density gradients, it is well known that vorticity deposition occurs. When two non-planar blast waves interact, a strong shock will propagate through the internal structure of each blast wave where the shock encounters such density gradients. There is therefore the potential for the resulting vorticity to produce pronounced density structures long after the passage of these shocks. If the two blast waves have evolved to the self-similar (Sedov) phase this is not a likely prospect, but for blast waves at a relatively early stage of their evolution this remains possible. We show, using 2D numerical simulations, that the interactions of two 'marginally young' blast waves can lead to strong vorticity deposition which leads to the generation of a strong protrusion and vortex ring as mass is driven into the internal structure of the weaker blast wave.

  3. Study of high Mach number laser driven blast waves in gases

    SciTech Connect

    Edens, A. D.; Adams, R. G.; Rambo, P.; Ruggles, L.; Smith, I. C.; Porter, J. L. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Ditmire, T. [Department of Physics, Texas Center for High Intensity Laser Science, University of Texas at Austin, Austin, Texas 78712 (United States)

    2010-11-15

    A series of experiments were performed examining the evolution of blast waves produced by laser irradiation of a target immersed in gas. Blast waves were produced by illumination of wires by 1 kJ, 1 ns laser pulses from the Z-Beamlet laser at Sandia National Laboratories. The blast waves were imaged by probe laser pulses at various times to examine the trajectory, radiative precursor, and induced perturbations on the blast wave front. Well defined perturbations were induced on the blast wave front with arrays of wires placed in the gas and the results of the experiments are compared to the theoretical predictions for the Vishniac overstability. It is found that the experimental results are in general agreement with these theoretical predictions on thin blast wave shells and are in quantitative agreement in the simplest case.

  4. Relativistic shock waves in viscous gluon matter

    E-print Network

    I. Bouras; E. Molnar; H. Niemi; Z. Xu; A. El; O. Fochler; C. Greiner; D. H. Rischke

    2009-07-22

    We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio $\\eta/s$ from zero to infinity. We show that an $\\eta/s$ ratio larger than 0.2 prevents the development of well-defined shock waves on timescales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.

  5. Mechanically tuned relativistic backward wave oscillator

    Microsoft Academic Search

    S. A. Kitsanov; S. D. Korovin; A. I. Klimov; V. V. Rostov; E. M. Tot’meninov

    2004-01-01

    A high-power relativistic microwave oscillator with low magnetic field is created based on a backward wave oscillator (BWO)\\u000a with resonance reflector. For fixed parameters of the slow-wave structure (SWS) and the electron beam, the oscillation frequency\\u000a of this BWO can be mechanically tuned within a 12% band by moving the resonance reflector relative to the SWS. A maximum output\\u000a pulse

  6. Relativistic Shock Waves in Viscous Gluon Matter

    SciTech Connect

    Bouras, I.; Xu, Z.; El, A.; Fochler, O.; Greiner, C. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main (Germany); Molnar, E.; Niemi, H. [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany); Rischke, D. H. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany)

    2009-07-17

    We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio eta/s from zero to infinity. We show that an eta/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.

  7. SECONDARY MISSILES GENERATED BY NUCLEAR-PRODUCED BLAST WAVES

    Microsoft Academic Search

    I. G. Bowen; M. E. Franklin; E. R. Fletcher; R. W. Albright

    1962-01-01

    The generation of secondary missiles by blast waves was investigated in ;\\u000a Operation Plumbbob for three nuclear detonations with estimated yields of 11, 38, ;\\u000a and 44.5 kt. A trapping technique was used to determine the impact velocities ;\\u000a for 17,524 missiles (stones, glass fragments, spheres, and military debris or ;\\u000a steel fragments) which occurred in open areas, houses, and

  8. IMAGING HIGH SPEED PARTICLES IN EXPLOSIVE DRIVEN BLAST WAVES

    SciTech Connect

    Jenkins, C. M. [Dept. of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611-6450 (United States); Air Force Research Laboratory, Munitions Directorate, Eglin AFB FL 32542 (United States); Horie, Y. [Air Force Research Laboratory, Munitions Directorate, Eglin AFB FL 32542 (United States); Ripley, R. C.; Wu, C.-Y. [Martec Limited, Suite 400-1888 Brunswick Street, Halifax, NS, B3J3J8 (Canada)

    2009-12-28

    This research describes a new application of a commercially available particle image velocimetry (PIV) instrument adapted for imaging particles in a blast wave. Powder was dispersed through the PIV light sheet using a right circular cylindrical charge containing aluminum powder filled in the annular space between the explosive core and exterior paper tube wall of the charge. Images acquired from each shot showed particle agglomeration and unique structures with the smaller particle diameters having developed structured appearances.

  9. Imaging High Speed Particles in Explosive Driven Blast Waves

    NASA Astrophysics Data System (ADS)

    Jenkins, C. M.; Horie, Y.; Ripley, R. C.; Wu, C.-Y.

    2009-12-01

    This research describes a new application of a commercially available particle image velocimetry (PIV) instrument adapted for imaging particles in a blast wave. Powder was dispersed through the PIV light sheet using a right circular cylindrical charge containing aluminum powder filled in the annular space between the explosive core and exterior paper tube wall of the charge. Images acquired from each shot showed particle agglomeration and unique structures with the smaller particle diameters having developed structured appearances.

  10. A thoracic mechanism of mild traumatic brain injury due to blast pressure waves.

    PubMed

    Courtney, A C; Courtney, M W

    2009-01-01

    The mechanisms by which blast pressure waves cause mild-to-moderate traumatic brain injury (mTBI) are an open question. Possibilities include acceleration of the head, direct passage of the blast wave via the cranium, and propagation of the blast wave to the brain via a thoracic mechanism. The hypothesis that the blast pressure wave reaches the brain via a thoracic mechanism is considered in light of ballistic and blast pressure wave research. Ballistic pressure waves, caused by penetrating ballistic projectiles or ballistic impacts to body armor, can only reach the brain via an internal mechanism and have been shown to cause cerebral effects. Similar effects have been documented when a blast pressure wave has been applied to the whole body or focused on the thorax in animal models. While vagotomy reduces apnea and bradycardia due to ballistic or blast pressure waves, it does not eliminate neural damage in the brain, suggesting that the pressure wave directly affects the brain cells via a thoracic mechanism. An experiment is proposed which isolates the thoracic mechanism from cranial mechanisms of mTBI due to blast wave exposure. Results have implications for evaluating risk of mTBI due to blast exposure and for developing effective protection. PMID:18829180

  11. Afterglow emission in gamma-ray bursts - I. Pair-enriched ambient medium and radiative blast waves

    NASA Astrophysics Data System (ADS)

    Nava, L.; Sironi, L.; Ghisellini, G.; Celotti, A.; Ghirlanda, G.

    2013-08-01

    Forward shocks caused by the interaction between a relativistic blast wave and the circumburst medium are thought to be responsible for the afterglow emission in gamma-ray bursts (GRBs). We consider the hydrodynamics of a spherical relativistic blast wave expanding into the surrounding medium and we generalize the standard theory in order to account for several effects that are generally ignored. In particular, we consider the role of adiabatic and radiative losses in the hydrodynamical evolution of the shock, under the assumption that the cooling losses are fast. Our model can describe adiabatic, fully radiative and semiradiative blast waves, and can describe the effects of a time-varying radiative efficiency. The equations we present are valid for arbitrary density profiles, and also for a circumburst medium enriched with electron-positron pairs. The presence of pairs enhances the fraction of shock energy gained by the leptons, thus increasing the importance of radiative losses. Our model allows us to study whether the high-energy (>0.1 GeV) emission in GRBs may originate from afterglow radiation. In particular, it is suitable to test whether the fast decay of the high-energy light curve observed in several Fermi Large Area Telescope GRBs can be ascribed to an initial radiative phase, followed by the standard adiabatic evolution.

  12. A parametric study of self-similar blast waves.

    NASA Technical Reports Server (NTRS)

    Oppenheim, A. K.; Kuhl, A. L.; Lundstrom, E. A.; Kamel, M. M.

    1972-01-01

    Comprehensive examination of self-similar blast waves with respect to two parameters, one describing the front velocity and the other the variation of the ambient density immediately ahead of the front. All possible front trajectories are taken into account, including limiting cases of the exponential and logarithmic form. The structure of the waves is analyzed by means of a phase plane defined in terms of two reduced coordinates. Loci of extrema of the integral curves in the phase plane are traced, and loci of singularities are determined on the basis of their intersections. Boundary conditons are introduced for the case where the medium into which the waves propagate is at rest. Representative solutions, pertaining to all the possible cases of blast waves bounded by shock fronts propagating into an atmosphere of uniform density, are obtained by evaluating the integral curves and determining the corresponding profiles of the gasdynamic parameters. Particular examples of integral curves for waves bounded by detonations are given, and all the degenerate solutions corresponding to cases where the integral curve is reduced to a point are delineated.

  13. Relativistic Quaternionic Wave Equation II

    E-print Network

    Charles Schwartz

    2007-04-05

    Further results are reported for the one-component quaternionic wave equation recently introduced. A Lagrangian is found for the momentum-space version of the free equation; and another, nonlocal in time, is found for the complete equation. Further study of multi-particle systems has us looking into the mathematics of tensor products of Hilbert spaces. The principles of linearity and superposition are also clarified to good effect in advancing the quaternionic theory.

  14. Millimeter-Wave HF Relativistic Electron Oscillators

    Microsoft Academic Search

    V. L. Bratman; G. G. Denisov; M. M. Ofitserov; S. D. Korovin; S. D. Polevin; V. V. Rostov

    1987-01-01

    A review of the experimental study of single-mode oscillators based on stimulated bremsstrahlung and Cerenkov radiation of high-current relativistic electron beams is given. Three types of Cerenkov oscillators are investigated in detail: orotrons, surface wave oscillators and a flimatron (free electron maser (FEM) based on Smith-Purcell radiation). The bremsstrahlung oscillators studied are gyrotrons with TM modes, a ubitron operating at

  15. Nonlinear waves in strongly interacting relativistic fluids

    E-print Network

    D. A. Fogaça; F. S. Navarra; L. G. Ferreira Filho

    2012-12-31

    During the past decades the study of strongly interacting fluids experienced a tremendous progress. In the relativistic heavy ion accelerators, specially the RHIC and LHC colliders, it became possible to study not only fluids made of hadronic matter but also fluids of quarks and gluons. Part of the physics program of these machines is the observation of waves in this strongly interacting medium. From the theoretical point of view, these waves are often treated with li-nearized hydrodynamics. In this text we review the attempts to go beyond linearization. We show how to use the Reductive Perturbation Method to expand the equations of (ideal and viscous) relativistic hydrodynamics to obtain nonlinear wave equations. These nonlinear wave equations govern the evolution of energy density perturbations (in hot quark gluon plasma) or baryon density perturbations (in cold quark gluon plasma and nuclear matter). Different nonlinear wave equations, such as the breaking wave, Korteweg-de Vries and Burgers equations, are obtained from different equations of state (EOS). In nuclear matter, the Walecka EOS may lead to a KdV equation. We explore equations of state such as those extracted from the MIT Bag Model and from QCD in the mean field theory approach. Some of these equations are integrable and have analytical solitonic solutions. We derive these equations also in spherical and cylindrical coordinates. We extend the analysis to two and three dimensions to obtain the Kadomtsev-Petviashvili (KP) equation, which is the generalization of the KdV. The KP is also integrable and presents analytical solitonic solutions. In viscous relativistic hydrodynamics we have second order patial derivatives which physically represent dissipation terms. We present numerical solutions and their corresponding algorithms for the cases where the equations are not integrable.

  16. GAMMA-RAY BURST AFTERGLOW SCALING RELATIONS FOR THE FULL BLAST WAVE EVOLUTION

    SciTech Connect

    Van Eerten, Hendrik J.; MacFadyen, Andrew I. [Center for Cosmology and Particle Physics, Physics Department, New York University, New York, NY 10003 (United States)

    2012-03-10

    We demonstrate that gamma-ray burst afterglow spectra and light curves can be calculated for arbitrary explosion and radiation parameters by scaling the peak flux and the critical frequencies connecting different spectral regimes. Only one baseline calculation needs to be done for each jet opening angle and observer angle. These calculations are done numerically using high-resolution relativistic hydrodynamical afterglow blast wave simulations which include the two-dimensional dynamical features of expanding and decelerating afterglow blast waves. Any light curve can then be generated by applying scaling relations to the baseline calculations. As a result, it is now possible to fully fit for the shape of the jet break, e.g., at early-time X-ray and optical frequencies. In addition, late-time radio calorimetry can be improved since the general shape of the transition into the Sedov-Taylor regime is now known for arbitrary explosion parameters so the exact moment when the Sedov-Taylor asymptote is reached in the light curve is no longer relevant. When calculating the baselines, we find that the synchrotron critical frequency {nu}{sub m} and the cooling break frequency {nu}{sub c} are strongly affected by the jet break. The {nu}{sub m} temporal slope quickly drops to the steep late-time Sedov-Taylor slope, while the cooling break {nu}{sub c} first steepens and then rises to meet the level of its shallow late-time asymptote.

  17. Linear wave propagation in relativistic magnetohydrodynamics

    E-print Network

    R. Keppens; Z. Meliani

    2008-10-14

    The properties of linear Alfv\\'en, slow, and fast magnetoacoustic waves for uniform plasmas in relativistic magnetohydrodynamics (MHD) are discussed, augmenting the well-known expressions for their phase speeds with knowledge on the group speed. A 3+1 formalism is purposely adopted to make direct comparison with the Newtonian MHD limits easier and to stress the graphical representation of their anisotropic linear wave properties using the phase and group speed diagrams. By drawing these for both the fluid rest frame and for a laboratory Lorentzian frame which sees the plasma move with a three-velocity having an arbitrary orientation with respect to the magnetic field, a graphical view of the relativistic aberration effects is obtained for all three MHD wave families. Moreover, it is confirmed that the classical Huygens construction relates the phase and group speed diagram in the usual way, even for the lab frame viewpoint. Since the group speed diagrams correspond to exact solutions for initial conditions corresponding to a localized point perturbation, their formulae and geometrical construction can serve to benchmark current high-resolution algorithms for numerical relativistic MHD.

  18. Experimental study of the hydrodynamics of high Mach number blast waves

    Microsoft Academic Search

    Aaron Douglas Edens

    2005-01-01

    We have performed a series of experiments examining the properties of high Mach number blast waves. Preliminary experiments were conducted on the Janus laser at Lawrence Livermore National Laboratory while the majority of experiments were carried out on the Z-Beamlet laser at Sandia National Laboratories. We created blast waves in the laboratory by using 10 J - 1000 J laser

  19. Model for small arms fire muzzle blast wave propagation in air

    NASA Astrophysics Data System (ADS)

    Aguilar, Juan R.; Desai, Sachi V.

    2011-11-01

    Accurate modeling of small firearms muzzle blast wave propagation in the far field is critical to predict sound pressure levels, impulse durations and rise times, as functions of propagation distance. Such a task being relevant to a number of military applications including the determination of human response to blast noise, gunfire detection and localization, and gun suppressor design. Herein, a time domain model to predict small arms fire muzzle blast wave propagation is introduced. The model implements a Friedlander wave with finite rise time which diverges spherically from the gun muzzle. Additionally, the effects in blast wave form of thermoviscous and molecular relaxational processes, which are associated with atmospheric absorption of sound were also incorporated in the model. Atmospheric absorption of blast waves is implemented using a time domain recursive formula obtained from numerical integration of corresponding differential equations using a Crank-Nicholson finite difference scheme. Theoretical predictions from our model were compared to previously recorded real world data of muzzle blast wave signatures obtained by shooting a set different sniper weapons of varying calibers. Recordings containing gunfire acoustical signatures were taken at distances between 100 and 600 meters from the gun muzzle. Results shows that predicted blast wave slope and exponential decay agrees well with measured data. Analysis also reveals the persistency of an oscillatory phenomenon after blast overpressure in the recorded wave forms.

  20. Computational Study of Human Head Response to Primary Blast Waves of Five Levels from Three Directions

    PubMed Central

    Wang, Chenzhi; Pahk, Jae Bum; Balaban, Carey D.; Miller, Mark C.; Wood, Adam R.; Vipperman, Jeffrey S.

    2014-01-01

    Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts. PMID:25409326

  1. Heating of X-Ray Hot Gas in Groups by Blast Waves

    NASA Astrophysics Data System (ADS)

    Fujita, Yutaka

    2001-03-01

    In order to find the conditions that determine whether X-ray hot gas in galaxy groups (intragroup gas [IGG]) is heated externally or internally, we investigate the evolution of blast waves in galaxy groups growing on a hierarchical clustering scenario. We find that the blast waves driven by quasars are confined in groups and heat the IGG internally at z<~1. However, at z>~1, they expel the IGG from groups; the expelled gas may fall back into the groups later as externally heated gas. Moreover, this may explain the observed low metal abundance of IGG. For blast waves driven by strong starbursts, the shift of the fate of blast waves occurs at z~3. On the other hand, although blast waves driven by weak starbursts do not expel IGG from groups, the heating efficiency decreases at z>~3 because of radiative cooling. It will be useful to compare these results with XMM-Newton observations.

  2. Numerical Study on Blast Wave Propagation Driven by Unsteady Ionization Plasma

    SciTech Connect

    Ogino, Yousuke; Sawada, Keisuke [Department of Aerospace Engineering, Tohoku University, Sendai 980-8579 (Japan); Ohnishi, Naofumi [Department of Aerospace Engineering, Tohoku University, Sendai 980-8579 (Japan); Center for Research Strategy and Support, Tohoku University, Sendai 980-8579 (Japan)

    2008-04-28

    Understanding the dynamics of laser-produced plasma is essential for increasing the available thrust and energy conversion efficiency from a pulsed laser to a blast wave in a gas-driven laser-propulsion system. The performance of a gas-driven laser-propulsion system depends heavily on the laser-driven blast wave dynamics as well as on the ionizing and/or recombining plasma state that sustains the blast wave. In this study, we therefore develop a numerical simulation code for a laser-driven blast wave coupled with time-dependent rate equations to explore the formation of unsteady ionizing plasma produced by laser irradiation. We will also examine the various properties of blast waves and unsteady ionizing plasma for different laser input energies.

  3. Spike penetration in blast-wave-driven instabilities

    NASA Astrophysics Data System (ADS)

    Drake, R. P.

    2009-11-01

    Recent experiments by C. Kuranz and collaborators, motivated by structure in supernovae, have studied systems in which planar blast waves encounter interfaces where the density decreases. During the Rayleigh-Taylor (RT) phase of such experiments, they observed greater penetration of the RT spikes than tends to be seen in simulations. Here we seek to employ semi-analytic theory to understand the general nature and regimes of spike penetration for blast-wave-driven instabilities. This problem is not trivial as one must account for the initial vorticity deposition at the interface, for its time-dependent deceleration, for the expansion of the shocked material in time and space, and for the drag on the broadened tips of the spikes. One can hope that such models will increase our ability to interpret the behavior of simulations of such systems, in both the laboratory and astrophysics. 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.

  4. Spike Penetration in Blast-Wave-Driven Instabilities

    NASA Astrophysics Data System (ADS)

    Drake, R. Paul

    2010-05-01

    Recent experiments by C. Kuranz and collaborators, motivated by structure in supernovae, have studied systems in which planar blast waves encounter interfaces where the density decreases. During the Rayleigh-Taylor (RT) phase of such experiments, they observed greater penetration of the RT spikes than tends to be seen in simulations. Here we seek to employ semi-analytic theory to understand the general nature and regimes of spike penetration for blast-wave-driven instabilities. This problem is not trivial as one must account for the initial vorticity deposition at the interface, for its time-dependent deceleration, for the expansion of the shocked material in time and space, and for the drag on the broadened tips of the spikes. We offer here an improved evaluation of the material expansion in comparison to past work. The goal is to use such models to increase our ability to interpret the behavior of simulations of such systems, in both the laboratory and astrophysics. 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.

  5. High resolution imaging of colliding blast waves in cluster media

    NASA Astrophysics Data System (ADS)

    Smith, Roland A.; Lazarus, James; Hohenberger, Matthias; Marocchino, Alberto; Robinson, Joseph S.; Chittenden, Jeremy P.; Moore, Alastair S.; Gumbrell, Edward T.; Dunne, Mike

    2007-12-01

    Strong shocks and blast wave collisions are commonly observed features in astrophysical objects such as nebulae and supernova remnants. Numerical simulations often underpin our understanding of these complex systems, however modelling of such extreme phenomena remains challenging, particularly so for the case of radiative or colliding shocks. This highlights the need for well-characterized laboratory experiments both to guide physical insight and to provide robust data for code benchmarking. Creating a sufficiently high-energy-density gas medium for conducting scaled laboratory astrophysics experiments has historically been problematic, but the unique ability of atomic cluster gases to efficiently couple to intense pulses of laser light now enables table top scale (1 J input energy) studies to be conducted at gas densities of >1019 particles cm-3 with an initial energy density >5 × 109 J g-1. By laser heating atomic cluster gas media we can launch strong (up to Mach 55) shocks in a range of geometries, with and without radiative precursors. These systems have been probed with a range of optical and interferometric diagnostics in order to retrieve electron density profiles and blast wave trajectories. Colliding cylindrical shock systems have also been studied, however the strongly asymmetric density profiles and radial and longitudinal mass flow that result demand a more complex diagnostic technique based on tomographic phase reconstruction. We have used the 3D magnetoresistive hydrocode GORGON to model these systems and to highlight interesting features such as the formation of a Mach stem for further study.

  6. Self-similar blast waves incorporating deflagrations of variable speed

    NASA Technical Reports Server (NTRS)

    Guirguis, R. H.; Kamel, M. M.; Oppenheim, A. K.

    1983-01-01

    The present investigation is concerned with the development of a systematic approach to the problem of self-similar blast waves incorporating nonsteady flames. The regime covered by the presented solutions is bounded on one side by an adiabatic strong explosion and, on the other, by deflagration propagating at an infinite acceleration. Results for a representative set of accelerations are displayed, taking into account the full range of propagation speeds from zero to velocities corresponding to the Chapman-Jouguet deflagration. It is found that the distribution of stored energy in the undisturbed medium determines the acceleration of the deflagration-shock wave system. The obtained results reveal the existence of a simple relation between the location of the deflagration and its Mach number.

  7. Radiative precursors driven by converging blast waves in noble gases

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L. [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom)] [Blackett Laboratory, Imperial College London SW7 2BW (United Kingdom); Williams, R. J. R. [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom)] [Atomic Weapons Establishment, Aldermaston RG7 4PR (United Kingdom); Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W. [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States)] [Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States); and others

    2014-03-15

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20?km s{sup ?1} blast waves through gases of densities of the order 10{sup ?5} g cm{sup ?3} (see Burdiak et al. [High Energy Density Phys. 9(1), 52–62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  8. Radiative precursors driven by converging blast waves in noble gases

    NASA Astrophysics Data System (ADS)

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Swadling, G. F.; Suzuki-Vidal, F.; Hall, G. N.; Khoory, E.; Pickworth, L.; Bland, S. N.; de Grouchy, P.; Skidmore, J.; Suttle, L.; Bennett, M.; Niasse, N. P. L.; Williams, R. J. R.; Blesener, K.; Atoyan, L.; Cahill, A.; Hoyt, C.; Potter, W.; Rosenberg, E.; Schrafel, P.; Kusse, B.

    2014-03-01

    A detailed study of the radiative precursor that develops ahead of converging blast waves in gas-filled cylindrical liner z-pinch experiments is presented. The experiment is capable of magnetically driving 20 km s-1 blast waves through gases of densities of the order 10-5 g cm-3 (see Burdiak et al. [High Energy Density Phys. 9(1), 52-62 (2013)] for a thorough description). Data were collected for Ne, Ar, and Xe gas-fills. The geometry of the setup allows a determination of the plasma parameters both in the precursor and across the shock, along a nominally uniform line of sight that is perpendicular to the propagation of the shock waves. Radiation from the shock was able to excite NeI, ArII, and XeII/XeIII precursor spectral features. It is shown that the combination of interferometry and optical spectroscopy data is inconsistent with upstream plasmas being in LTE. Specifically, electron density gradients do not correspond to any apparent temperature change in the emission spectra. Experimental data are compared to 1D radiation hydrodynamics HELIOS-CR simulations and to PrismSPECT atomic physics calculations to assist in a physical interpretation of the observations. We show that upstream plasma is likely in the process of being radiatively heated and that the emission from a small percentage of ionised atoms within a cool background plasma dominates the emission spectra. Experiments were carried out on the MAGPIE and COBRA pulsed-power facilities at Imperial College London and Cornell University, respectively.

  9. Numerical simulation of blast wave interaction with structure columns

    Microsoft Academic Search

    Yanchao Shi; Hong Hao; Zhong-Xian Li

    2007-01-01

    Accurate estimation of blast loads on structures is essential for reliable predictions of structural response and damage.\\u000a Current practice in blast effect analysis and design estimates blast loads primarily based on empirical formulae obtained\\u000a from field blast tests. Due to the limited availability of test data, those empirical formulae are usually applicable to the\\u000a case that the reflection surface of

  10. Blast waves from violent explosive activity at Yasur Volcano, Vanuatu

    NASA Astrophysics Data System (ADS)

    Marchetti, E.; Ripepe, M.; Delle Donne, D.; Genco, R.; Finizola, A.; Garaebiti, E.

    2013-11-01

    and seismic waveforms were collected during violent strombolian activity at Yasur Volcano (Vanuatu). Averaging ~3000 seismic events showed stable waveforms, evidencing a low-frequency (0.1-0.3 Hz) signal preceding ~5-6 s the explosion. Infrasonic waveforms were mostly asymmetric with a sharp compressive (5-106 Pa) onset, followed by a small long-lasting rarefaction phase. Regardless of the pressure amplitude, the ratio between the positive and negative phases was constant. These waveform characteristics closely resembled blast waves. Infrared imagery showed an apparent cold spherical front ~20 m thick, which moved between 342 and 405 m/s before the explosive hot gas/fragments cloud. We interpret this cold front as that produced by the vapor condensation induced by the passage of the shock front. We suggest that violent strombolian activity at Yasur was driven by supersonic dynamics with gas expanding at 1.1 Mach number inside the conduit.

  11. Spike morphology in blast-wave-driven instability experiments

    NASA Astrophysics Data System (ADS)

    Kuranz, C. C.; Drake, R. P.; Grosskopf, M. J.; Fryxell, B.; Budde, A.; Hansen, J. F.; Miles, A. R.; Plewa, T.; Hearn, N.; Knauer, J.

    2010-05-01

    The laboratory experiments described in the present paper observe the blast-wave-driven Rayleigh-Taylor instability with three-dimensional (3D) initial conditions. About 5 kJ of energy from the Omega laser creates conditions similar to those of the He-H interface during the explosion phase of a supernova. The experimental target is a 150 ?m thick plastic disk followed by a low-density foam. The plastic piece has an embedded, 3D perturbation. The basic structure of the pattern is two orthogonal sine waves where each sine wave has an amplitude of 2.5 ?m and a wavelength of 71 ?m. In some experiments, an additional wavelength is added to explore the interaction of modes. In experiments with 3D initial conditions the spike morphology differs from what has been observed in other Rayleigh-Taylor experiments and simulations. Under certain conditions, experimental radiographs show some mass extending from the interface to the shock front. Current simulations show neither the spike morphology nor the spike penetration observed in the experiments. The amount of mass reaching the shock front is analyzed and potential causes for the spike morphology and the spikes reaching the shock are discussed. One such hypothesis is that these phenomena may be caused by magnetic pressure, generated by an azimuthal magnetic field produced by the plasma dynamics.

  12. Spike morphology in blast-wave-driven instability experiments

    SciTech Connect

    Kuranz, C. C.; Drake, R. P.; Grosskopf, M. J.; Fryxell, B.; Budde, A. [Department of Atmospheric, Oceanic and Space Science, Center for Radiative Shock Hydrodynamics, University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109 (United States); Hansen, J. F.; Miles, A. R. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Plewa, T. [Department of Scientific Computing, Florida State University, 400 Dirac Science Library, Tallahassee, Florida 32306 (United States); Hearn, N. [Center for Astrophysical Thermonuclear Flashes, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637 (United States); Knauer, J. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

    2010-05-15

    The laboratory experiments described in the present paper observe the blast-wave-driven Rayleigh-Taylor instability with three-dimensional (3D) initial conditions. About 5 kJ of energy from the Omega laser creates conditions similar to those of the He-H interface during the explosion phase of a supernova. The experimental target is a 150 {mu}m thick plastic disk followed by a low-density foam. The plastic piece has an embedded, 3D perturbation. The basic structure of the pattern is two orthogonal sine waves where each sine wave has an amplitude of 2.5 {mu}m and a wavelength of 71 {mu}m. In some experiments, an additional wavelength is added to explore the interaction of modes. In experiments with 3D initial conditions the spike morphology differs from what has been observed in other Rayleigh-Taylor experiments and simulations. Under certain conditions, experimental radiographs show some mass extending from the interface to the shock front. Current simulations show neither the spike morphology nor the spike penetration observed in the experiments. The amount of mass reaching the shock front is analyzed and potential causes for the spike morphology and the spikes reaching the shock are discussed. One such hypothesis is that these phenomena may be caused by magnetic pressure, generated by an azimuthal magnetic field produced by the plasma dynamics.

  13. Middle ear injury in animals exposed to complex blast waves inside an armored vehicle.

    PubMed

    Phillips, Y Y; Mundie, T G; Hoyt, R; Dodd, K T

    1989-05-01

    With greater reliance on armored vehicles of improved survivability, questions have arisen about the likelihood of the wounding of vehicle occupants from blast waves alone. In this study, we placed anesthetized animals (sheep or pigs) inside lightly armored vehicles and exposed them to the blast waves generated by one of three sizes of shaped-charge munitions. Sixty-seven animals were exposed and 15 served as controls. No difference was noted between exposed and control groups for blast injury to the respiratory or gastrointestinal tracts. In contrast, middle ear damage was observed exclusively in animals exposed to blast and was correlated strongly with the peak pressure. The ear is the organ most sensitive to blast damage, and if protectors are not used, military physicians can expect to see a high incidence of middle ear injury in modern combat. The operational consequences of such an injury are not known. PMID:2497694

  14. RANKINE-HUGONIOT RELATIONS IN RELATIVISTIC COMBUSTION WAVES

    SciTech Connect

    Gao Yang; Law, Chung K., E-mail: cklaw@princeton.edu [Center for Combustion Energy and Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

    2012-12-01

    As a foundational element describing relativistic reacting waves of relevance to astrophysical phenomena, the Rankine-Hugoniot relations classifying the various propagation modes of detonation and deflagration are analyzed in the relativistic regime, with the results properly degenerating to the non-relativistic and highly relativistic limits. The existence of negative-pressure downstream flows is noted for relativistic shocks, which could be of interest in the understanding of the nature of dark energy. Entropy analysis for relativistic shock waves is also performed for relativistic fluids with different equations of state (EoS), denoting the existence of rarefaction shocks in fluids with adiabatic index {Gamma} < 1 in their EoS. The analysis further shows that weak detonations and strong deflagrations, which are rare phenomena in terrestrial environments, are expected to exist more commonly in astrophysical systems because of the various endothermic reactions present therein. Additional topics of relevance to astrophysical phenomena are also discussed.

  15. Electromagnetic wave equations for relativistically degenerate quantum magnetoplasmas.

    PubMed

    Masood, Waqas; Eliasson, Bengt; Shukla, Padma K

    2010-06-01

    A generalized set of nonlinear electromagnetic quantum hydrodynamic (QHD) equations is derived for a magnetized quantum plasma, including collisional, electron spin- 1/2, and relativistically degenerate electron pressure effects that are relevant for dense astrophysical systems, such as white dwarfs. For illustrative purposes, linear dispersion relations are derived for one-dimensional magnetoacoustic waves for a collisionless nonrelativistic degenerate gas in the presence of the electron spin- 1/2 contribution and for magnetoacoustic waves in a plasma containing relativistically degenerate electrons. It is found that both the spin and relativistic degeneracy at high densities tend to slow down the magnetoacoustic wave due to the Pauli paramagnetic effect and relativistic electron mass increase. The present study outlines the theoretical framework for the investigation of linear and nonlinear behaviors of electromagnetic waves in dense astrophysical systems. The results are applied to calculate the magnetoacoustic speeds for both the nonrelativistic and relativistic electron degeneracy cases typical for white dwarf stars. PMID:20866534

  16. Energy-momentum relation for solitary waves of relativistic wave equations

    E-print Network

    T. V. Dudnikova; A. I. Komech; H. Spohn

    2005-08-23

    Solitary waves of relativistic invariant nonlinear wave equation with symmetry group U(1) are considered. We prove that the energy-momentum relation for spherically symmetric solitary waves coincides with the Einstein energy-momentum relation for point particles.

  17. Modeling of weak blast wave propagation in the lung.

    PubMed

    D'yachenko, A I; Manyuhina, O V

    2006-01-01

    Blast injuries of the lung are the most life-threatening after an explosion. The choice of physical parameters responsible for trauma is important to understand its mechanism. We developed a one-dimensional linear model of an elastic wave propagation in foam-like pulmonary parenchyma to identify the possible cause of edema due to the impact load. The model demonstrates different injury localizations for free and rigid boundary conditions. The following parameters were considered: strain, velocity, pressure in the medium and stresses in structural elements, energy dissipation, parameter of viscous criterion. Maximum underpressure is the most suitable wave parameter to be the criterion for edema formation in a rabbit lung. We supposed that observed scattering of experimental data on edema severity is induced by the physiological variety of rabbit lungs. The criterion and the model explain this scattering. The model outlines the demands for experimental data to make an unambiguous choice of physical parameters responsible for lung trauma due to impact load. PMID:16214154

  18. Relativistic soliton-like collisionless ionization wave

    NASA Astrophysics Data System (ADS)

    Arefiev, Alexey; McCormick, Matthew; Quevedo, Hernan; Bengtson, Roger; Ditmire, Todd

    2014-10-01

    It has been observed in recent experiments with laser-irradiated gas jets that a plasma filament produced by the laser and containing energetic electrons can launch a relativistic ionization wave into ambient gas. Here we present a self-consistent theory that explains how a collisionless ionization wave can propagate in a self-sustaining regime. A population of hot electrons necessarily generates a sheath electric field at the plasma boundary. This field penetrates the ambient gas, ionizing the gas atoms and thus causing the plasma boundary to expand. We show that the motion of the newly generated electrons can form a potential well adjacent to the plasma boundary. The outwards motion of the well causes a bunch of energetic electrons to become trapped, while allowing the newly generated electrons to escape into the plasma without retaining much energy. The resulting soliton-like ionizing field structure propagates outwards with a bunch of hot electrons that maintain a strong sheath field despite significant plasma expansion. We also present 1D and 2D particle-in-cell simulations that illustrate the described mechanism. The simulations were performed using HPC resources provided by the Texas Advanced Computing Center. This work was supported by NNSA Contract No. DE-FC52-08NA28512 and U.S. DOE Contract No. DE-FG02-04ER54742.

  19. Relativistic Jet Response to Precession and Wave-Wave Interactions

    E-print Network

    P. Hardee; P. Hughes; A. Rosen; E. Gomez

    2001-03-14

    Three dimensional numerical simulations of the response of a Lorentz factor 2.5 relativistic jet to precession at three different frequencies have been performed. Low, moderate and high precession frequencies have been chosen relative to the maximally unstable frequency predicted by a Kelvin-Helmholtz stability analysis. Transverse motion and velocity decreases as the precession frequency increases. Although helical displacement of the jet decreases in amplitude as the precession frequency increases, a helical shock is generated in the medium external to the jet at all precession frequencies. Complex pressure and velocity structure inside the jet is shown to be produced by a combination of the helical surface and first body modes predicted by a normal mode analysis of the relativistic hydrodynamic equations. The surface and first body mode have different wave speed and wavelength, are launched in phase by the periodic precession, and exhibit beat patterns in synthetic emission images. Wave (pattern) speeds range from $0.41c$ to $0.86c$ but beat patterns remain stationary. Thus, we find a mechanism that can produce differentially moving and stationary features in the jet.

  20. Rankine-Hugoniot Relations in Relativistic Combustion Waves

    E-print Network

    Gao, Yang

    2012-01-01

    As a foundational element describing relativistic reacting waves of relevance to astrophysical phenomena, the Rankine-Hugoniot relations classifying the various propagation modes of detonation and deflagration are analyzed in the relativistic regime, with the results properly degenerating to the non-relativistic and highlyrelativistic limits. The existence of negative-pressure downstream flows is noted for relativistic shocks, which could be of interest in the understanding of the nature of dark energy. Entropy analysis for relativistic shock waves are also performed for relativistic fluids with different equations of state (EoS), denoting the existence of rarefaction shocks in fluids with adiabatic index \\Gamma < 1 in their EoS. The analysis further shows that weak detonations and strong deflagrations, which are rare phenomena in terrestrial environments, are expected to exist more commonly in astrophysical systems because of the various endothermic reactions present therein. Additional topics of relevanc...

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

    PubMed Central

    Chen, Yun; Huang, Wei; Constantini, Shlomi

    2012-01-01

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

  2. Full-Trajectory Diagnosis of Laser-Driven Radiative Blast Waves in Search of Thermal Plasma Instabilities

    SciTech Connect

    Moore, A. S.; Gumbrell, E. T.; Lazarus, J.; Hohenberger, M.; Robinson, J. S.; Smith, R. A.; Plant, T. J. A.; Symes, D. R.; Dunne, M. [Plasma Physics Division, AWE Aldermaston, RG7 4PR. United Kingdom (United Kingdom); Laser Consortium, Blackett Laboratory, Imperial College, London SW7 2BZ. United Kingdom (United Kingdom); Ministry of Defence, Foxhill, Bath BA1 5AB. United Kingdom (United Kingdom); Central Laser Facility, Rutherford Appleton Laboratory, Oxfordshire OX11 0QX. United Kingdom (United Kingdom)

    2008-02-08

    Experimental investigations into the dynamics of cylindrical, laser-driven, high-Mach-number shocks are used to study the thermal cooling instability predicted to occur in astrophysical radiative blast waves. A streaked Schlieren technique measures the full blast-wave trajectory on a single-shot basis, which is key for observing shock velocity oscillations. Electron density profiles and deceleration parameters associated with radiative blast waves were recorded, enabling the calculation of important blast-wave parameters including the fraction of radiated energy, {epsilon}, as a function of time for comparison with radiation-hydrodynamics simulations.

  3. Disturbances of the ionosphere of blast and acoustic waves generated at ionospheric heights by rockets

    NASA Astrophysics Data System (ADS)

    Drobzheva, Ya. V.; Krasnov, V. M.; Sokolova, O. I.

    2003-11-01

    In this paper we present a model, which describes the propagation of acoustic impulses produced by flight of rockets through a model terrestrial atmosphere, and effect of these impulses onto the ionosphere above a rocket. We show, that experimentally observed ionospheric disturbances with duration about 300s cannot be explained by effect of acoustic impulses onto the ionosphere. We have calculated parameters of a blast wave produced by launch vehicle on the ionospheric heights. It was shown that the blast wave is intense and this wave can generate great disturbance of electron density. The disturbance of electron density can exceed the ambient electron density in 2.6 times. We supposed that the observed ionospheric disturbances might be produced by propagation of delayed magnetoacoustic wave, which, in turn, was produced by the blast wave.

  4. Disturbances of the ionosphere of blast and acoustic waves generated at ionospheric heights by rockets

    NASA Astrophysics Data System (ADS)

    Drobzheva, Y.; Krasnov, V.

    2003-04-01

    We present a model, which describes the propagation of acoustic pulses through the atmosphere produced by flight of rockets, and effects of these pulses on the ionosphere above a rocket. The model takes into account nonlinear effects, inhomogeneities of the atmosphere, absorption, expansion of a wave acoustic front, etc. We show, that experimentally observed ionospheric disturbances with duration about hundreds seconds cannot be explained by effect of acoustic pulses on the ionosphere. We calculated parameters of a blast wave generated by rocket at the ionospheric heights. It was shown that the blast wave is intense and it can generate great disturbance of electron density. The disturbance of electron density can exceed the ambient electron density 2.6 as much. We supposed that the observed ionospheric disturbances might be generated by propagation of delayed magnetoacoustic wave generated during the propagation of a blast wave through the ionosphere.

  5. Computation of viscous blast wave solutions with an upwind finite volume method

    NASA Technical Reports Server (NTRS)

    Molvik, Gregory A.

    1987-01-01

    A fully conservative, viscous, implicit, upwind, finite-volume scheme for the thin-layer Navier-Stokes equations is described with application to blast wave flow fields. In this scheme, shocks are captured without the oscillations typical of central differencing techniques and wave speeds are accurately predicted. The finite volume philosophy ensures conservation and since boundary conditions are also treated conservatively, accurate reflections of waves from surfaces are assured. Viscous terms in the governing equations are treated in a manner consistent with the finite volume philosophy, resulting in very accurate prediction of boundary layer quantities. Numerical results are presented for four viscous problems: a steady boundary layer, a shock-induced boundary layer, a blast wave/cylinder interaction and a blast wave/supersonic missile interaction. Comparisons of the results with an established boundary layer code, similarity solution, and experimental data show excellent agreement.

  6. Spherical Gravitational Waves in Relativistic Theory of Gravitation

    E-print Network

    A. A. Leonovich; Yu. P. Vyblyi

    2012-11-13

    Within the framework of relativistic theory of gravitation the exact spherically-symmetric wave solution is received. It is shown that this solution possesses the positive-definite energy and momentum deriving with the Fock energy-momentum density tensor of gravitational field. In this connection the sense of Birkhoff theorem in Relativistic Theory of Gravitation is discussed.

  7. Imaging High Speed Particles in Explosive Driven Blast Waves

    NASA Astrophysics Data System (ADS)

    Jenkins, Charles; Horie, Yasuyuki

    2009-06-01

    Researchers Mr. Charles Jenkins and Dr. Yasuyuki Horie at the High Explosive Research & Development (HERD) facility at Eglin AFB with sponsorship from DTRA has successfully imaged high speed explosively driven metallic particles. The process uses an adapted, commercially available Particle Image Velocimetry (PIV) instrument. Regional and particle flow vectors are determined from particle displacement between two images taken in rapid succession. The instrument consists of a 120 mJ, pulsed Nd:YAG laser, camera system, synchronizer, and proprietary imaging software. The new PIV capability provides the ability for scientists and engineers to map explosively driven metallic particles in a blast wave. Characteristics of particle motion, interaction and dispersion can be determined by this method, providing measurements of key parameters such as particle size, shape, velocity, and concentration. This new capability to image and track small (from a few microns to as large as several hundred microns) high-speed particles without direct intervention by physical means, ensures that the particles are unchanged in their environment and provides greater measurement accuracy of particle dynamics in very short time scales. The capability can also be used to map large areas (square feet) or to zoom down at higher magnifications to study particle features such as particle agglomeration.

  8. A Blast Wave from the 1843 Eruption of Eta Carinae

    E-print Network

    Nathan Smith

    2008-09-09

    Very massive stars shed much of their mass in violent precursor eruptions as luminous blue variables (LBVs) before reaching their most likely end as supernovae, but the cause of LBV eruptions is unknown. The 19th century eruption of Eta Carinae, the prototype of these events, ejected about 12 solar masses at speeds of 650 km/s, with a kinetic energy of almost 10^50 ergs. Some faster material with speeds up to 1000-2000 km/s had previously been reported but its full distribution was unknown. Here I report observations of much faster material with speeds up to 3500-6000 km/s, reaching farther from the star than the fastest material in earlier reports. This fast material roughly doubles the kinetic energy of the 19th century event, and suggests that it released a blast wave now propagating ahead of the massive ejecta. Thus, Eta Car's outer shell now mimics a low-energy supernova remnant. The eruption has usually been discussed in terms of an extreme wind driven by the star's luminosity, but fast material reported here suggests that it was powered by a deep-seated explosion rivalling a supernova, perhaps triggered by the pulsational pair instability. This may alter interpretations of similar events seen in other galaxies.

  9. Prospects for studying how high-intensity compression waves cause damage in human blast injuries

    NASA Astrophysics Data System (ADS)

    Brown, Katherine; Bo, Chiara; Ramaswamy, Arul; Masouros, Spiros; Newell, Nicolas; Hill, Adam; Clasper, Jon; Bull, Anthony; Proud, William

    2011-06-01

    Blast injuries arising from improvised explosive devices are often complex leading to long-term disability in survivors. There is an urgent need to mitigate against the effects of blast that lead to these injuries, and to also improve post-traumatic therapeutic treatments related to problems associated with damage and healing processes and infections. We have initiated multidisciplinary studies to develop experimental facilities and strategies for analyzing the effects blast waves upon the human body, from cellular through to skeletal functions. This work is supported by the Atomic Weapons Establishment and the Defence Science and Technology Laboratory, UK.

  10. Interaction between blast wave and reticulated foam: assessing the potential for auditory protection systems

    NASA Astrophysics Data System (ADS)

    Wilgeroth, J. M.; Nguyen, T.-T. N.; Proud, W. G.

    2014-05-01

    Injuries to the tympanic membrane (ear drum) are particularly common in individuals subjected to blast overpressure such as military personnel engaged in conflict. Here, the interaction between blast wave and reticulated foams of varying density and thickness has been investigated using shock tube apparatus. The degree of mitigation afforded by the foam samples is discussed in relation to an injury threshold which has been suggested by others for the tympanic membrane.

  11. DYNAMICS AND AFTERGLOW LIGHT CURVES OF GAMMA-RAY BURST BLAST WAVES WITH A LONG-LIVED REVERSE SHOCK

    SciTech Connect

    Uhm, Z. Lucas; Zhang Bing [Department of Physics and Astronomy, University of Nevada-Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154 (United States); Hascoeet, Romain; Daigne, Frederic; Mochkovitch, Robert [Institut d'Astrophysique de Paris, UMR 7095 Universite Pierre et Marie Curie-CNRS, 98 bis Boulevard Arago, F-75014 Paris (France); Park, Il H., E-mail: uhm@physics.unlv.edu [Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2012-12-20

    We perform a detailed study on the dynamics of a relativistic blast wave with the presence of a long-lived reverse shock (RS). Although a short-lived RS has been widely considered, the RS is believed to be long-lived as a consequence of a stratification expected on the ejecta Lorentz factors. The existence of a long-lived RS causes the forward shock (FS) dynamics to deviate from a self-similar Blandford-McKee solution. Employing the ''mechanical model'' that correctly incorporates the energy conservation, we present an accurate solution for both the FS and RS dynamics. We conduct a sophisticated calculation of the afterglow emission. Adopting a Lagrangian description of the blast wave, we keep track of an adiabatic evolution of numerous shells between the FS and RS. An evolution of the electron spectrum is also followed individually for every shell. We then find the FS and RS light curves by integrating over the entire FS and RS shocked regions, respectively. Exploring a total of 20 different ejecta stratifications, we explain in detail how a stratified ejecta affects its blast wave dynamics and afterglow light curves. We show that, while the FS light curves are not sensitive to the ejecta stratifications, the RS light curves exhibit much richer features, including steep declines, plateaus, bumps, re-brightenings, and a variety of temporal decay indices. These distinctive RS features may be observable if the RS has higher values of the microphysics parameters than the FS. We discuss possible applications of our results in understanding the gamma-ray burst afterglow data.

  12. Relativistic electron scattering by magnetosonic waves: Effects of discrete wave emission and high wave amplitudes

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Mourenas, D.; Agapitov, O. V.; Krasnoselskikh, V. V.

    2015-06-01

    In this paper, we study relativistic electron scattering by fast magnetosonic waves. We compare results of test particle simulations and the quasi-linear theory for different spectra of waves to investigate how a fine structure of the wave emission can influence electron resonant scattering. We show that for a realistically wide distribution of wave normal angles ? (i.e., when the dispersion ? ? ? 0.5 ° ), relativistic electron scattering is similar for a wide wave spectrum and for a spectrum consisting in well-separated ion cyclotron harmonics. Comparisons of test particle simulations with quasi-linear theory show that for ? ? > 0.5 ° , the quasi-linear approximation describes resonant scattering correctly for a large enough plasma frequency. For a very narrow ? distribution (when ? ? ˜ 0.05 ° ), however, the effect of a fine structure in the wave spectrum becomes important. In this case, quasi-linear theory clearly fails in describing accurately electron scattering by fast magnetosonic waves. We also study the effect of high wave amplitudes on relativistic electron scattering. For typical conditions in the earth's radiation belts, the quasi-linear approximation cannot accurately describe electron scattering for waves with averaged amplitudes >300 pT. We discuss various applications of the obtained results for modeling electron dynamics in the radiation belts and in the Earth's magnetotail.

  13. Spectral properties of blast-wave models of gamma-ray burst sources

    NASA Technical Reports Server (NTRS)

    Meszaros, P.; Rees, M. J.; Papathanassiou, H.

    1994-01-01

    We calculate the spectrum of blast-wave models of gamma-ray burst sources, for various assumptions about the magnetic field density and the relativistic particle acceleration efficiency. For a range of physically plausible models we find that the radiation efficiency is high and leads to nonthermal spectra with breaks at various energies comparable to those observed in the gamma-ray range. Radiation is also predicted at other wavebands, in particular at X-ray, optical/UV, and GeV/TeV energies. We discuss the spectra as a function of duration for three basic types of models, and for cosmological, halo, and galactic disk distances. We also evaluate the gamma-ray fluences and the spectral characteristics for a range of external densities. Impulsive burst models at cosmological distances can satisfy the conventional X-ray paucity constraint S(sub x)/S(sub gamma)less than a few percent over a wide range of durations, but galactic models can do so only for bursts shorter than a few seconds, unless additional assumptions are made. The emissivity is generally larger for bursts in a denser external environment, with the efficiency increasing up to the point where all the energy input is radiated away.

  14. Matter Density and Relativistic Models of Wave Function Collapse

    E-print Network

    Daniel Bedingham; Detlef Duerr; GianCarlo Ghirardi; Sheldon Goldstein; Roderich Tumulka; Nino Zanghi

    2013-07-12

    Mathematical models for the stochastic evolution of wave functions that combine the unitary evolution according to the Schroedinger equation and the collapse postulate of quantum theory are well understood for non-relativistic quantum mechanics. Recently, there has been progress in making these models relativistic. But even with a fully relativistic law for the wave function evolution, a problem with relativity remains: Different Lorentz frames may yield conflicting values for the matter density at a space-time point. We propose here a relativistic law for the matter density function. According to our proposal, the matter density function at a space-time point x is obtained from the wave function psi on the past light cone of x by setting the i-th particle position in |psi|^2 equal to x, integrating over the other particle positions, and averaging over i. We show that the predictions that follow from this proposal agree with all known experimental facts.

  15. Investigation of ULF Wave Modulation of Relativistic Electron Precipitation

    NASA Astrophysics Data System (ADS)

    Woodger, L. A.; Sample, J. G.; Millan, R. M.

    2013-12-01

    Loss processes greatly impact the dynamics of Earth's radiation belts. Balloon payloads can provide information about loss to the atmosphere through observations of bremsstrahlung x-rays emitted from precipitating relativistic electrons. The Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) provides spatial and temporal information about precipitating electron events through an array of slowly drifting balloons distributed in magnetic local time and L values. Duskside relativistic electron precipitation events observed by previous balloon-borne x-ray detectors have been reported, and frequently show modulation on ULF wave timescales (Foat et al., 1998; Millan et al., 2002). Similar observations were recently made during the 2013 BARREL Campaign. Theoretical studies have suggested ULF waves are capable of precipitating relativistic electrons in the outer radiation belts (Brito et al., 2012). This study takes an observational approach to investigate the relationship between ULF waves and balloon observations of modulated duskside REP events.

  16. Rapid X-ray Declines and Plateaus in Swift GRB Light Curves Explained by A Highly Radiative Blast Wave

    E-print Network

    Charles D. Dermer

    2007-04-22

    GRB X-ray light curves display rapid declines followed by a gradual steepening or plateau phase in >~ 30% of GRBs in the Swift sample. Treating the standard relativistic blastwave model in a uniform circumburst medium, it is shown that if GRBs accelerate ultra-high energy cosmic rays through a Fermi mechanism, then the hadronic component can be rapidly depleted by means of photopion processes on time scales ~100 - 10^4 s after the GRB explosion. While discharging the hadronic energy in the form of ultra-high energy cosmic ray neutrals and escaping cosmic-ray ions, the blast wave goes through a strongly radiative phase, causing the steep declines observed with Swift. Following the discharge, the blast wave recovers its adiabatic behavior, forming the observed plateaus or slow declines. These effects are illustrated by calculations of model bolometric light curves. The results show that steep X-ray declines and plateau features occur when GRB sources take place in rather dense media, with n >~ 100 cc out to >~ 10^17 cm.

  17. The Formation of a Blast Wave by a Very Intense Explosion. II. The Atomic Explosion of 1945

    E-print Network

    Ravelet, Florent

    The Formation of a Blast Wave by a Very Intense Explosion. II. The Atomic Explosion of 1945 of a blast wave by a very intense explosion. 11. The atomic explosion of 1945 BYSIRGEOBFREYTAYLOR,P.R.S. (Received 10 November 1949) [Plates 7 t o 91 Photographs by J.E. Mack of the first atomic explosion in New

  18. A ballistic model-based method for ranging direct fire weapons using the acoustic muzzle blast and shock wave

    Microsoft Academic Search

    Kam W. Lo; Brian G. Ferguson

    2008-01-01

    A direct fire weapon (rifle) produces an impulsive sound (muzzle blast) associated with the firing of a bullet. If the bullet travels at a supersonic speed, another impulsive sound (ballistic shock wave) is generated by the passage of the bullet. A ballistic model-based method which uses both the acoustic muzzle blast and shock wave for ranging direct fire weapons is

  19. Bernstein-Greene-Kruskal waves in relativistic cold plasma

    NASA Astrophysics Data System (ADS)

    Singh Verma, Prabal; Sengupta, Sudip; Kaw, Predhiman

    2012-03-01

    We construct the longitudinal traveling wave solution [Akhiezer and Polovin, Sov. Phys. JETP 3, 696 (1956)] from the exact space and time dependent solution of relativistic cold electron fluid equations [Infeld and Rowlands, Phys. Rev. Lett. 62, 1122 (1989)]. Ions are assumed to be static. We also suggest an alternative derivation of the Akhiezer Polovin solution after making the standard traveling wave Ansatz.

  20. Ion Motions in Magnetosonic Shock Waves with Relativistic Propagation Speeds

    Microsoft Academic Search

    Shinji Nakazawa; Yukiharu Ohsawa

    1998-01-01

    Ion motions in shock waves propagating perpendicular to a magnetic field are studied through theory and simulation; the shocks with relativistic propagation speeds are considered. In such shocks the longitudinal electric fields are less important than in nonrelativistic ones. From the analysis of ion orbits it is found that ion velocities parallel to the wave front can be comparable to

  1. Space-charge waves on relativistic elliptic electron beams

    SciTech Connect

    Brainerd, Andrew E.; Chen Chiping [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Zhou, Jing [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Beam Power Technology, Incorporated, 5 Rolling Green Lane, Chelmsford, Massachusetts 01824 (United States)

    2009-07-15

    This paper reports on results of a small-signal analysis of space-charge waves on a relativistic elliptic electron beam immersed in a strong axial magnet field in a perfectly conducting tunnel with an elliptic cross section. A dispersion relation for the space-charge waves is derived analytically. A computer code, elliptic-beam small signal, is developed and used in studies of the dispersion characteristics of fast- and slow-space-charge waves on relativistic elliptic electron beams. Applications of the theory in elliptic-beam klystrons are discussed.

  2. Investigating EMIC Waves as a Precipitation Mechanism for Relativistic Electrons

    NASA Astrophysics Data System (ADS)

    Li, Z.; Millan, R. M.; Woodger, L. A.

    2012-12-01

    Evidence has indicated that EMIC waves may be one of the major causes of relativistic electron precipitation (REP). We solved the pitch-angle diffusion equation for the scattering of relativistic electrons by EMIC waves, and generated flux-energy spectra of the precipitating electrons. After being converted into Bremsstrahlung X-ray counts, these spectra can be directly compared with previous (e.g. MAXIS, MINIS, BARREL test campaigns) and future (e.g. BARREL) balloon spectra measurements to determine if EMIC waves are the causes of the REP events. Parameter studies have also been conducted to investigate the influence of various geomagnetic parameters and environmental conditions on the REP spectra.

  3. Linear surface waves propagating along discontinuities within a relativistic plasma

    SciTech Connect

    Dragila, R.; Vukovic, S.

    1989-09-01

    A relativistic two-fluid theory of linear surface waves propagating along the density and/or temperature discontinuity within a relativistic plasma has been developed. The effect of relativistic temperatures can be described by an increase of the effective particle mass by a factor proportional to the enthalpy per unit rest mass. As the electron temperature increases, the surface wave frequency spectrum is downshifted and shrinks and the contribution of the ion component to the dispersion properties becomes increasingly pronounced. In addition to the ''standard'' situation in the theory of surface waves when one deals with a density discontinuity, now a surface wave-type solution formally exists even in a homogeneous plasma containing a temperature discontinuity.

  4. Nonlinear magnetosonic waves in dense plasmas with non-relativistic and ultra-relativistic degenerate electrons

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Mahmood, S.; Rehman, Aman-ur-

    2014-11-01

    Linear and nonlinear propagation of magnetosonic waves in the perpendicular direction to the ambient magnetic field is studied in dense plasmas for non-relativistic and ultra-relativistic degenerate electrons pressure. The sources of nonlinearities are the divergence of the ions and electrons fluxes, Lorentz forces on ions and electrons fluids and the plasma current density in the system. The Korteweg-de Vries equation for magnetosonic waves propagating in the perpendicular direction of the magnetic field is derived by employing reductive perturbation method for non-relativistic as well as ultra-relativistic degenerate electrons pressure cases in dense plasmas. The plots of the magnetosonic wave solitons are also shown using numerical values of the plasma parameters such a plasma density and magnetic field intensity of the white dwarfs from literature. The dependence of plasma density and magnetic field intensity on the magnetosonic wave propagation is also pointed out in dense plasmas for both non-relativistic and ultra-relativistic degenerate electrons pressure cases.

  5. Relativistic scattered wave calculations on UF6

    NASA Technical Reports Server (NTRS)

    Case, D. A.; Yang, C. Y.

    1980-01-01

    Self-consistent Dirac-Slater multiple scattering calculations are presented for UF6. The results are compared critically to other relativistic calculations, showing that the results of all molecular orbital calculations are in qualitative agreement, as measured by energy levels, population analyses, and spin-orbit splittings. A detailed comparison is made to the relativistic X alpha(RX alpha) method of Wood and Boring, which also uses multiple scattering theory, but incorporates relativistic effects in a more approximate fashion. For the most part, the RX alpha results are in agreement with the present results.

  6. Effects of internal heat transfer on the structure of self-similar blast waves

    NASA Technical Reports Server (NTRS)

    Ghoniem, A. F.; Berger, S. A.; Oppenheim, A. K.; Kamel, M. M.

    1982-01-01

    An analysis of the problem of self-similar, nonadiabatic blast waves, where both conduction and radiation are allowed to take place, show the problem to be reducible to the integration of a system of six coupled nonlinear ordinary differential equations. Consideration of these equations shows that although radiation tends to produce uniform fields through temperature gradient attenuation, all the energy carried by radiation is deposited on the front and the bounding shock becomes increasingly overdriven. When conduction is taken into account, the distribution of gasdynamic parameters in blast waves in the case of Rosseland diffusion radiation is more uniform than in the case of the Planck emission radiation.

  7. Studying radiative shocks using laser driven blast waves in clustered gases

    NASA Astrophysics Data System (ADS)

    Symes, D. R.; Hohenberger, M.; Doyle, H. W.; Smith, R. A.; Moore, A. S.; Gumbrell, E. T.; Rodriguez, R.; Gil, J. M.

    2011-10-01

    We report on the creation of radiative blast waves by irradiating gases of atomic clusters with intense short pulse laser light. The efficient absorption of the cluster medium leads to high energy deposition and development into a cylindrical shock. These non-equilibrium, optically thin shocks have great potential for hydrodynamic scaling with astrophysical relevance, particularly for supernova remnants. We discuss how cluster blast waves may become susceptible to spatial and temporal instabilities and the application of the RAPCAL atomic physics code to determine our plasma conditions.

  8. Relativistic wave and particle mechanics formulated without classical mass

    SciTech Connect

    Fry, J.L. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Musielak, Z.E., E-mail: zmusielak@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Chang, Trei-wen [Department of Physics, National Kaohsiung Normal University, Kaohsiung 802, Taiwan (China)

    2011-08-15

    Highlights: > Formal derivation of the Klein-Gordon equation with an invariant frequency. > Formal derivation of the relativistic version of Newton's equation. > The classical mass is replaced by the invariant frequency. > The invariant frequencies for selected elementary particles are deduced. > The choice of natural units resulting from the developed theories is discussed. - Abstract: The fact that the concept of classical mass plays an important role in formulating relativistic theories of waves and particles is well-known. However, recent studies show that Galilean invariant theories of waves and particles can be formulated with the so-called 'wave mass', which replaces the classical mass and allows attaining higher accuracy of performing calculations [J.L. Fry and Z.E. Musielak, Ann. Phys. 325 (2010) 1194]. The main purpose of this paper is to generalize these results and formulate fundamental (Poincare invariant) relativistic theories of waves and particles without the classical mass. In the presented approach, the classical mass is replaced by an invariant frequency that only involves units of time. The invariant frequencies for various elementary particles are deduced from experiments and their relationship to the corresponding classical and wave mass for each particle is described. It is shown that relativistic wave mechanics with the invariant frequency is independent of the Planck constant, and that such theory can attain higher accuracy of performing calculations. The choice of natural units resulting from the developed theories of waves and particles is also discussed.

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

    SciTech Connect

    Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)] [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)

    2013-12-15

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

  10. Design of a maze structure to attenuate blast waves

    SciTech Connect

    Bacigalupi, C.M.

    1980-03-19

    Building criteria for cells used to process and store high explosives dictated maze-type entries, to avoid mechanical closure devices. Experiments were conducted to develop a minimum-cost maze configuration that would limit the effects of an accidental 10-kg detonation to acceptable levels (<15 psig reflected) in adjacent areas. Components of suppressive design that were considered were right-angle turns, blast deflectors, baffles (reduced-area openings), and energy-absorbing materials. The proposed configuration uses multiple baffles and a blast deflector to reduce the exit pressure to about 8 psig reflected.

  11. Extended adiabatic blast waves and a model of the soft X-ray background. [interstellar matter

    NASA Technical Reports Server (NTRS)

    Cox, D. P.; Anderson, P. R.

    1981-01-01

    An analytical approximation is generated which follows the development of an adiabatic spherical blast wave in a homogeneous ambient medium of finite pressure. An analytical approximation is also presented for the electron temperature distribution resulting from coulomb collisional heating. The dynamical, thermal, ionization, and spectral structures are calculated for blast waves of energy E sub 0 = 5 x 10 to the 50th power ergs in a hot low-density interstellar environment. A formula is presented for estimating the luminosity evolution of such explosions. The B and C bands of the soft X-ray background, it is shown, are reproduced by such a model explosion if the ambient density is about .000004 cm, the blast radius is roughly 100 pc, and the solar system is located inside the shocked region. Evolution in a pre-existing cavity with a strong density gradient may, it is suggested, remove both the M band and OVI discrepancies.

  12. Blast Overpressure Waves Induce Transient Anxiety and Regional Changes in Cerebral Glucose Metabolism and Delayed Hyperarousal in Rats

    PubMed Central

    Awwad, Hibah O.; Gonzalez, Larry P.; Tompkins, Paul; Lerner, Megan; Brackett, Daniel J.; Awasthi, Vibhudutta; Standifer, Kelly M.

    2015-01-01

    Physiological alterations, anxiety, and cognitive disorders are strongly associated with blast-induced traumatic brain injury (blast TBI), and are common symptoms in service personnel exposed to blasts. Since 2006, 25,000–30,000 new TBI cases are diagnosed annually in U.S. Service members; increasing evidence confirms that primary blast exposure causes diffuse axonal injury and is often accompanied by altered behavioral outcomes. Behavioral and acute metabolic effects resulting from blast to the head in the absence of thoracic contributions from the periphery were examined, following a single blast wave directed to the head of male Sprague-Dawley rats protected by a lead shield over the torso. An 80?psi head blast produced cognitive deficits that were detected in working memory. Blast TBI rats displayed increased anxiety as determined by elevated plus maze at day 9 post-blast compared to sham rats; blast TBI rats spent significantly more time than the sham controls in the closed arms (p?blast. Instead, blast TBI rats displayed increased rearing behavior at day 48 post-blast compared to sham rats. Blast TBI rats also exhibited suppressed acoustic startle responses, but similar pre-pulse inhibition at day 15 post-blast compared to sham rats. Acute physiological alterations in cerebral glucose metabolism were determined by positron emission tomography 1 and 9?days post-blast using 18F-fluorodeoxyglucose (18F-FDG). Global glucose uptake in blast TBI rat brains increased at day 1 post-blast (p?blast injury. Markers for reactive astrogliosis and neuronal damage were noted by immunoblotting motor cortex tissue from day 10 post-blast in blast TBI rats compared to sham controls (p?

  13. Nonlinear hydrodynamic Langmuir waves in fully degenerate relativistic plasma

    NASA Astrophysics Data System (ADS)

    Haas, F.; Kourakis, I.

    2015-04-01

    The combined effect of special relativity and electron degeneracy on Langmuir waves is analyzed by utilizing a rigorous fully relativistic hydrodynamic model. Assuming a traveling wave solution form, a set of conservation laws is identified, together with a pseudo-potential function depending on the relativistic parameter pF/(m c) (where pF is the Fermi momentum, m is the mass of the charge carriers and c the speed of light), as well as on the amplitude of the electrostatic energy perturbation.

  14. Blast Waves and Explosions Sound generation by explosive decompression of an airplane

    Microsoft Academic Search

    J. E. Shepherd; H. G. Hornung

    2005-01-01

    We examine sound generation by the explosive decompression of a pressurized airplane in flight. The near-field is numerically computed by assuming the sudden removal of an axial section of an idealized, streamlined, cylindrical fuselage with an external flow simulating flight. After an initial transient period, we find a nearly circular blast wave with a leading shock strength that is highest

  15. Adaptation of flux-corrected transport algorithms for modelling blast waves

    Microsoft Academic Search

    J. P. Boris; M. A. Fry; R. H. Guirguis; A. L. Kuhl

    1982-01-01

    Flux-corrected transport represents an accurate and flexible class of methods for solving nonsteady compressible flow problems. In models which treat all the physical effects required for blast wave simulation, truncation errors inherent in the underlying finite-difference scheme are exacerbated by nonlinear coupling between the fluid equations and by the greater complexity of the phenomena being simulated. In order to improve

  16. Relativistic backward wave oscillators: Theory and experiment

    Microsoft Academic Search

    B. Levush; A. Bromborsky; W. R. Lou; D. Abe; S. Miller; Y. Carmel; J. Rodgers; V. Granatstein; W. Destler

    1991-01-01

    The linear and nonlinear theory of backward-wave oscillators (BWOs) is developed taking into account reflection of the electromagnetic wave at the boundaries of the slow wave structure. The effects of finite duration and rise time of the electron beam pulse on device operation are discussed. A series of low-current experiments attempting to measure the start current has been conducted. The

  17. Surfatron acceleration of a relativistic particle by electromagnetic plane wave

    E-print Network

    A. I. Neishtadt; A. A. Vasiliev; A. V. Artemyev

    2010-11-09

    We study motion of a relativistic charged particle in a plane slow electromagnetic wave and background uniform magnetic field. The wave propagates normally to the background field. Under certain conditions, the resonance between the wave and the Larmor motion of the particle is possible. Capture into this resonance results in acceleration of the particle along the wave front (surfatron acceleration). We analyse the phenomenon of capture and show that a captured particle never leaves the resonance and its energy infinitely grows. Scattering on the resonance is also studied. We find that this scattering results in diffusive growth of the particle energy. Finally, we estimate energy losses due to radiation by an accelerated particle.

  18. Dynamics of Rarefaction Waves in General-Relativistic Collapsing Clouds

    E-print Network

    A. G. Zhilkin

    2006-07-23

    Formation and evolution of general relativistic collapse inhomogeneity is investigated. It is shown that a rarefaction wave forms at initial collapse stages and propagates inside from the cloud boundary to its center. The focusing time of the rarefaction wave is found. In massive clouds, the rarefaction wave focusing time equals the free-fall time. The collapse of such clouds leads to black hole formation. In low-mass clouds, the rarefaction wave focusing time is less than the free-fall time. After focusing, the collapse of such clouds becomes fully inhomogeneous and can be sufficiently decelerated by the pressure gradient.

  19. Particle acceleration in ultra-relativistic oblique shock waves

    E-print Network

    A. Meli; J. J. Quenby

    2002-12-13

    We perform Monte Carlo simulations of diffusive shock acceleration at highly relativistic oblique shock waves. High upstream flow Lorentz gamma factors are used, which are relevant to models of ultra relativistic particle shock acceleration in Active Galactic Nuclei (AGN) central engines and relativistic jets and Gamma Ray Burst (GRB) fireballs. We investigate numerically the acceleration properties -in the ultra relativistic flow regime of $\\Gamma \\sim 10-10^{3}$- such as angular distribution, acceleration time constant, particle energy gain versus number of crossings and spectral shapes. We perform calculations for sub-luminal and super-luminal shocks, using two different approaches respectively. The $\\Gamma^{2}$ energization for the first crossing cycle and the significantly large energy gain for subsequent crossings as well as the high 'speed up' factors found, are important in supporting the Vietri and Waxman models on GRB ultra-high energy cosmic ray, neutrino, and gamma-ray output.

  20. Relativistic harmonic content of nonlinear electromagnetic waves in underdense plasmas

    Microsoft Academic Search

    W. B. Mori; C. D. Decker; W. P. Leemans

    1993-01-01

    The relativistic harmonic content of large-amplitude electromagnetic waves propagating in underdense plasmas is investigated. The steady-state harmonic content of nonlinear linearly polarized waves is calculated for both the very underdense (wp\\/w 0)≪1 and critical density (wp\\/w0)≃1 limits. For weak nonlinearities, eE0\\/mc?0<1, the nonlinear source term for the third harmonic is derived for arbitrary wp\\/w0. Arguments are given for extending these

  1. Gravitational waves from instabilities in relativistic stars

    E-print Network

    N. Andersson

    2002-11-04

    This article provides an overview of stellar instabilities as sources of gravitational waves. The aim is to put recent work on secular and dynamical instabilities in compact stars in context, and to summarize the current thinking about the detectability of gravitational waves from various scenarios. As a new generation of kilometer length interferometric detectors are now coming online this is a highly topical theme. The review is motivated by two key questions for future gravitational-wave astronomy: Are the gravitational waves from various instabilities detectable? If so, what can these gravitational-wave signals teach us about neutron star physics? Even though we may not have clear answers to these questions, recent studies of the dynamical bar-mode instability and the secular r-mode instability have provided new insights into many of the difficult issues involved in modelling unstable stars as gravitational-wave sources.

  2. Loss of relativistic electrons at geosynchronous orbit by EMIC waves

    NASA Astrophysics Data System (ADS)

    Hyun, K.; Kim, K.; Lee, E.; Lee, D.

    2013-12-01

    There are several loss mechanisms for relativistic electrons in the Earth's outer radiation belt. They are associated with adiabatic and/or non-adiabatic processes. Adiabatic processes do not produce a real loss of radiation belt particles because the relativistic particle flux variations are modulated by the change in the magnetic field strength. That is, the flux decrease is due to the field decrease, and the flux recovers when the field returns. Secondly, non-adiabatic processes produce irreversible losses; in other words, particles are lost permanently. Unlike adiabatic processes, non-adiabatic processes lead to a permanent loss. One of them is atmospheric precipitation associated with wave-particle interactions or magnetic moment scattering due to field stretching. The other is the loss through the magnetopause, called magnetopause shadowing. Recently, it has been suggested that EMIC waves are responsible for relativistic electron loss. In this study we selected several intervals showing relativistic flux dropouts at geosynchronous orbit. Around the intervals, geosynchronous spacecraft observed well-defined EMIC waves. We examine if the EMIC waves are a major factor to control the flux dropouts at geosynchronous orbit. We also discuss the effect of other non-adiabatic mechanisms for the flux dropouts.

  3. Shock Tube Design for High Intensity Blast Waves for Laboratory Testing of Armor and Combat Materiel

    E-print Network

    Courtney, Elijah; Courtney, Michael

    2015-01-01

    Shock tubes create simulated blast waves which can be directed and measured to study blast wave effects under laboratory conditions. It is desirable to increase available peak pressure from ~1 MPa to ~5 MPa to simulate closer blast sources and facilitate development and testing of personal and vehicle armors. Three methods were investigated to increase peak simulated blast pressure produced by an oxy-acetylene driven shock tube while maintaining suitability for laboratory studies. The first method is the addition of a Shchelkin spiral priming section which works by increasing the turbulent flow of the deflagration wave, thus increasing its speed and pressure. This approach increased the average peak pressure from 1.17 MPa to 5.33 MPa while maintaining a relevant pressure-time curve (Friedlander waveform). The second method is a bottleneck between the driving and driven sections. Coupling a 79 mm diameter driving section to a 53 mm driven section increased the peak pressure from 1.17 MPa to 2.25 MPa. Using a 1...

  4. Relativistic particle motion in nonuniform electromagnetic waves

    NASA Technical Reports Server (NTRS)

    Schmidt, G.; Wilcox, T.

    1973-01-01

    It is shown that a charged particle moving in a strong nonuniform electromagnetic wave suffers a net acceleration in the direction of the negative intensity gradient of the wave. Electrons will be expelled perpendicularly from narrow laser beams and various instabilities can result.

  5. Laser-induced blast waves in air and their effect on monodisperse droplet chains of ethanol and kerosene

    NASA Astrophysics Data System (ADS)

    Gebel, G. C.; Mosbach, T.; Meier, W.; Aigner, M.

    2015-07-01

    Weak spherical blast waves in static air and their breakup of ethanol and Jet A-1 kerosene droplets were investigated. The blast waves were created by laser-induced air breakdowns at ambient temperature and pressure. In the first part of this study, they were visualized with schlieren imaging, and their trajectories were tracked with high temporal resolution. The laser pulse energy was varied to create blast waves of different strengths. Their initial energies were determined by the application of a numerical and a semi-empirical blast wave model. In the second part, monodisperse ethanol and kerosene droplet chains were injected. Their interaction with the blast waves was visualized by the application of shadowgraph imaging. The perpendicular distance of the breakdown origin toward the droplet chains was varied to study the effect on the fuel droplets as a function of the distance. Droplets within a few millimeters around the breakdown origin were disintegrated into two to three secondary droplets. The blast-induced flow velocities on the post-shock side and the corresponding Weber numbers were calculated from the data of a non-dimensional numerical simulation, and a close look was taken at the breakup process of the droplets. The analysis showed that the aerodynamic force of the blast-induced flow was sufficient to deform the droplets into disk-like shapes, but diminished too fast to accomplish breakup. Due to the release of strain energy, the deformed droplets relaxed, stretched into filaments and finally disintegrated by capillary pinching.

  6. Magnetic Fields In Blast-wave-driven Instability Experiments Relevant To Supernova

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn; Drake, R.; Grosskopf, M.; Krauland, C.; Marion, D.; Fryxell, B.; Budde, A.; Remington, B.; Robey, H.; Hansen, J.; Miles, A.; Knauer, J.; Arnett, D.; Meakin, C.; Plewa, T.; Hearn, N.

    2009-05-01

    These experiments are scaled to the blast wave driven instabilities at the He/H interface during the explosion phase of SN1987A. This core-collapse supernova was detected about 50 kpc from Earth making it the first supernova observed so closely to earth in modern times. The progenitor star was a blue supergiant with a mass of 18-20 solar masses. A blast wave occurred following the supernova explosion because there was a sudden, finite release of energy. Blast waves consist of a shock front followed by a rarefaction wave. When a blast wave crosses an interface with a decrease in density, hydrodynamic instabilities will develop. These experiments include target materials scaled in density to the He/H layer in SN1987A. About 5 kJ of laser energy from the Omega Laser facility irradiates a 150 µm plastic layer that is followed by a low-density foam layer. A blast wave structure similar to those in supernovae is created in the plastic layer. The blast wave crosses a three-dimensional interface with a wavelength of 71 µm in two orthogonal directions. This produces unstable growth dominated by the Rayleigh-Taylor (RT) instability. We have detected the interface structure under these conditions, using dual orthogonal radiography, and will show some of the resulting data. Recent advancements in our x-ray backlighting techniques have greatly improved the resolution of our x-ray radiographic images. Under certain conditions, the improved images show some mass extending beyond the RT spike and penetrating further than previously observed. Current simulations do not show this phenomenon. It is possible that magnetic pressure generated by orthogonal components of the electron density gradient and the electron temperature gradient cause the spikes to reach the shock front. The amount of mass in the spike extensions is discussed. This research was sponsored by the SSAA through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA00064

  7. Probing Black Holes and Relativistic Stars with Gravitational Waves

    E-print Network

    Kip S. Thorne

    1997-06-26

    In the coming decade, gravitational waves will convert the study of general relativistic aspects of black holes and stars from a largely theoretical enterprise to a highly interactive, observational/theoretical one. For example, gravitational-wave observations should enable us to observationally map the spacetime geometries around quiescient black holes, study quantitatively the highly nonlinear vibrations of curved spacetime in black-hole collisions, probe the structures of neutron stars and their equation of state, search for exotic types of general relativistic objects such as boson stars, soliton stars, and naked singularities, and probe aspects of general relativity that have never yet been seen such as the gravitational fields of gravitons and the influence of gravitational-wave tails on radiation reaction.

  8. Energy dissipation in wave propagation in general relativistic plasma

    E-print Network

    Ajanta Das; S. Chatterjee

    2009-11-03

    Based on a recent communication by the present authors the question of energy dissipation in magneto hydrodynamical waves in an inflating background in general relativity is examined. It is found that the expanding background introduces a sort of dragging force on the propagating wave such that unlike the Newtonnian case energy gets dissipated as it progresses. This loss in energy having no special relativistic analogue is, however, not mechanical in nature as in elastic wave. It is also found that the energy loss is model dependent and also depends on the number of dimensions.

  9. Blast Wave Formation by Laser-Sustained Nonequilibrium Plasma in the Laser-Driven In-Tube Accelerator Operation

    SciTech Connect

    Ogino, Yousuke; Ohnishi, Naofumi; Sawada, Keisuke [Department of Aeronautics and Space Engineering, Tohoku University, Sendai 980-8579 (Japan); Sasoh, Akihiro [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)

    2006-05-02

    Understanding the dynamics of laser-produced plasma is essentially important for increasing available thrust force in a gas-driven laser propulsion system such as laser-driven in-tube accelerator. A computer code is developed to explore the formation of expanding nonequilibrium plasma produced by laser irradiation. Various properties of the blast wave driven by the nonequilibrium plasma are examined. It is found that the blast wave propagation is substantially affected by radiative cooling effect for lower density case.

  10. Simulation and Measurements of Small Arms Blast Wave Overpressure in the Process of Designing a Silencer

    NASA Astrophysics Data System (ADS)

    Hristov, Nebojša; Kari, Aleksandar; Jerkovi?, Damir; Savi?, Slobodan; Sirovatka, Radoslav

    2015-02-01

    Simulation and measurements of muzzle blast overpressure and its physical manifestations are studied in this paper. The use of a silencer can have a great influence on the overpressure intensity. A silencer is regarded as an acoustic transducer and a waveguide. Wave equations for an acoustic dotted source of directed effect are used for physical interpretation of overpressure as an acoustic phenomenon. Decomposition approach has proven to be suitable to describe the formation of the output wave of the wave transducer. Electroacoustic analogies are used for simulations. A measurement chain was used to compare the simulation results with the experimental ones.

  11. Rarefaction wave in relativistic steady magnetohydrodynamic flows

    SciTech Connect

    Sapountzis, Konstantinos, E-mail: ksapountzis@phys.uoa.gr; Vlahakis, Nektarios, E-mail: vlahakis@phys.uoa.gr [Faculty of Physics, University of Athens, 15784 Zografos, Athens (Greece)

    2014-07-15

    We construct and analyze a model of the relativistic steady-state magnetohydrodynamic rarefaction that is induced when a planar symmetric flow (with one ignorable Cartesian coordinate) propagates under a steep drop of the external pressure profile. Using the method of self-similarity, we derive a system of ordinary differential equations that describe the flow dynamics. In the specific limit of an initially homogeneous flow, we also provide analytical results and accurate scaling laws. We consider that limit as a generalization of the previous Newtonian and hydrodynamic solutions already present in the literature. The model includes magnetic field and bulk flow speed having all components, whose role is explored with a parametric study.

  12. The physical properties of the blast wave produced by a stoichiometric propane/oxygen explosion

    NASA Astrophysics Data System (ADS)

    Dewey, M. C.; Dewey, J. M.

    2014-07-01

    The trajectory of the primary shock produced by the explosion of a nominal 18.14 t (20 tn) hemispherical propane/oxygen charge was analysed previously to provide the physical properties immediately behind the shock, but gave no information about the time-resolved properties throughout the blast wave. The present study maps all the physical properties of the wave throughout and beyond the positive durations for a range of distances from about 1.6-18 m scaled to a 1 kg charge at NTP. The physical properties were calculated using a hydro-code to simulate the flow field produced by a spherical piston moving with a specific trajectory. This technique has been used extensively to determine the physical properties of blast waves from a variety of sources for which the piston path was determined by high-speed photography of smoke tracers established close to the charges immediately before detonation. In the case of the propane/oxygen explosion, smoke tracer data were not available to determine the trajectory of the spherical piston. An arbitrary piston path was used and its trajectory iteratively adjusted until it produced a blast wave with a primary shock whose trajectory exactly matched the measured trajectory from the propane/oxygen explosion. Throughout the studied flow field the time histories of hydrostatic pressure, density and particle velocity are well described by fits to the modified Friedlander equation. The properties are presented as functions of scaled radius and are compared with the properties of the blast wave from a 1 kg TNT surface burst explosion, and with other measurements of the same explosion.

  13. Kinematics of ICMEs/Shocks: Blast Wave Reconstruction Using Type-II Emissions

    NASA Astrophysics Data System (ADS)

    Corona-Romero, P.; Gonzalez-Esparza, J. A.; Aguilar-Rodriguez, E.; De-la-Luz, V.; Mejia-Ambriz, J. C.

    2015-05-01

    We present a physical methodology for reconstructing the trajectory of interplanetary shocks using Type-II radio emission data. This technique calculates the shock trajectory assuming that the disturbance propagates as a blast wave in the interplanetary medium. We applied this blast-wave reconstruction (BWR) technique to analyze eight fast Earth-directed ICMEs/shocks associated with Type-II emissions. The technique deduces a shock trajectory that reproduces the Type-II frequency drifts and calculates shock onset speed, shock travel time, and shock speed at 1 AU. The BWR results agreed well with the Type-II spectra, with data from coronagraph images, in-situ measurements, and interplanetary scintillation observations. Perturbations in the Type-II data affect the accuracy of the BWR technique. This methodology could be applied to track interplanetary shocks causing Type-II emissions in real-time and to predict the shock arrival time and shock speed at 1 AU.

  14. Kinematics of ICMEs/shocks: blast wave reconstruction using type II emissions

    E-print Network

    Corona-Romero, P; Aguilar-Rodriguez, E; de-la-Luz, V; Mejia-Ambriz, J C

    2015-01-01

    We present a physical methodology to reconstruct the trajectory of interplanetary shocks using type II radio emission data. This technique calculates the shock trajectory assuming that the disturbance propagates as a blast wave in the interplanetary medium. We applied this Blast Wave Reconstruction (BWR) technique to analyze eight fast Earth-directed ICMEs/shocks associated with type II emissions. The technique deduces a shock trajectory that reproduces the type II frequency drifts, and calculates shock onset speed, shock transit time and shock speed at 1~AU. There were good agreements comparing the BWR results with the type II spectra, with data from coronagraph images, {\\it in situ} measurements, and interplanetary scintillation (IPS) observations. Perturbations on the type II data affect the accuracy of the BWR technique. This methodology could be applied to track interplanetary shocks causing TII emissions in real-time, to predict the shock arrival time and shock speed at 1~AU.

  15. Noncausal effects in relativistic wave equations

    NASA Technical Reports Server (NTRS)

    Guertin, R. F.; Wilson, T. L.

    1977-01-01

    Manifestly covariant wave equations describing particles with a unique mass and spin can, for certain types of external-field interactions, possess noncausal solutions. The paper reports a procedure for applying Pierce decomposition of all six couplings expressed in the Duffin-Kemmer-Petiau spin-0 formula. This treatment converts the equation to a form in which the causal properties are apparent. The conditions under which the causal properties of higher-spin equations can be made manifest are discussed.

  16. Noncausal effects in relativistic wave equations

    NASA Technical Reports Server (NTRS)

    Guertin, R. F.; Wilson, T. L.

    1977-01-01

    The problem of determining whether a given type of external field interaction will lead to noncausal wave propagation in the context of the five-component Duffin-Kemmer-Petiau (DKP) spin-0 theory is considered. It is shown that if a Peirce decomposition of the DKP spin-0 equation is applied for each of the couplings in the equation, the causal properties become apparent from the form of the operator H in the resulting Schroedinger-type equation.

  17. Interaction of supernova blast waves with wind-driven shells: formation of "jets", "bullets", "ears", etc

    E-print Network

    V. V. Gvaramadze

    1999-12-24

    Most of middle-aged supernova remnants (SNRs) have a distorted and complicated appearance which cannot be explained in the framework of the Sedov-Taylor model. We consider three typical examples of such SNRs (Vela SNR, MSH 15-52, G 309.2-00.6) and show that their structure could be explained as a result of interaction of a supernova (SN) blast wave with the ambient medium preprocessed by the action of the SN progenitor's wind and ionized emission.

  18. Calculation of wing response to gusts and blast waves with vortex lift effect

    NASA Technical Reports Server (NTRS)

    Chao, D. C.; Lan, C. E.

    1983-01-01

    A numerical study of the response of aircraft wings to atmospheric gusts and to nuclear explosions when flying at subsonic speeds is presented. The method is based upon unsteady quasi-vortex lattice method, unsteady suction analogy and Pade approximant. The calculated results, showing vortex lag effect, yield reasonable agreement with experimental data for incremental lift on wings in gust penetration and due to nuclear blast waves.

  19. Calculation of wing response to gusts and blast waves with vortex lift effect

    NASA Technical Reports Server (NTRS)

    Chao, D. C.; Lan, C. E.

    1983-01-01

    A numerical study of the response of aircraft wings to atmospheric gusts and to nuclear explosions when flying at subsonic speeds is presented. The method is based upon unsteady quasi-vortex-lattice method, unsteady suction analogy, and Pade approximate. The calculated results, showing vortex lag effect, yield reasonable agreement with experimental data for incremental lift on wings in gust penetration and due to nuclear blast waves.

  20. Biomechanical Assessment of Brain Dynamic Responses Due to Blast Pressure Waves

    Microsoft Academic Search

    M. S. Chafi; G. Karami; M. Ziejewski

    2010-01-01

    A mechanized and integrated computational scheme is introduced to determine the human brain responses in an environment where\\u000a the human head is exposed to explosions from trinitrotoluene (TNT), or other high-yield explosives, in military applications.\\u000a The procedure is based on a three-dimensional (3-D) non-linear finite element method (FEM) that implements a simultaneous\\u000a conduction of explosive detonation, shock wave propagation, blast–head

  1. Numerical modeling of the kinematics of turbulent mixing in HE-driven blast waves

    Microsoft Academic Search

    A. L. Kuhl; M. V. Wright

    1983-01-01

    High-explosive driven blast waves contain a contact surface which is Rayleigh-Taylor unstable. The kinematics of the mixing at this surface was studied numerically with a one dimensional hydrocode. A k-o turbulence model was used to simulate the growth and decay of turbulence for this problem; source terms were included to model the Rayleigh-Taylor instability mechanism. It is demonstrated that this

  2. Relativistic backward wave oscillator with a discrete resonance reflector

    Microsoft Academic Search

    S. D. Korovin; I. K. Kurkan; V. V. Rostov; E. M. Tot’meninov

    1999-01-01

    We study, both theoretically and experimentally, a relativistic backward wave oscillator BWO with a discrete resonance reflector.\\u000a It is shown that premodulation of electrons in the reflector region leads to considerable changes in the oscillator characteristics.\\u000a If a homogeneous slowingdown system (SS) is considered and the space charge is neglected, then the calculated maximum efficiency\\u000a of oscillation increases from 15%

  3. A relativistic backward wave oscillator with a modulating resonance reflector

    Microsoft Academic Search

    S. D. Korovin; V. V. Rostov; E. M. Tot’meninov

    2005-01-01

    A high-efficiency relativistic microwave source based on a backward wave oscillator (BWO) with a resonance reflector has been\\u000a studied by experimental and numerical methods. The BWO is capable of generating 12-ns pulses with a carrier frequency of 9.93\\u000a GHz at an output radiation power of 0.75 0.11 GW. For the BWO pumped by a high-current electron beam from a SINUS-6K

  4. Influence of ambient air pressure on the energy conversion of laser-breakdown induced blast waves

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2013-09-01

    Influence of ambient pressure on energy conversion efficiency from a Nd?:?glass laser pulse (? = 1.053 µm) to a laser-induced blast wave was investigated at reduced pressure. Temporal incident and transmission power histories were measured using sets of energy meters and photodetectors. A half-shadowgraph half-self-emission method was applied to visualize laser absorption waves. Results show that the blast energy conversion efficiency ?bw decreased monotonically with the decrease in ambient pressure. The decrease was small, from 40% to 38%, for the pressure change from 101 kPa to 50 kPa, but the decrease was considerable, to 24%, when the pressure was reduced to 30 kPa. Compared with a TEA-CO2-laser-induced blast wave (? = 10.6 µm), higher fraction absorption in the laser supported detonation regime ?LSD of 90% was observed, which is influenced slightly by the reduction of ambient pressure. The conversion fraction ?bw/?LSD?90% was achieved at pressure >50 kPa, which is significantly higher than that in a CO2 laser case.

  5. Chaotic Motion of Relativistic Electrons Driven by Whistler Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Telnikhin, A. A.; Kronberg, Tatiana K.

    2007-01-01

    Canonical equations governing an electron motion in electromagnetic field of the whistler mode waves propagating along the direction of an ambient magnetic field are derived. The physical processes on which the equations of motion are based .are identified. It is shown that relativistic electrons interacting with these fields demonstrate chaotic motion, which is accompanied by the particle stochastic heating and significant pitch angle diffusion. Evolution of distribution functions is described by the Fokker-Planck-Kolmogorov equations. It is shown that the whistler mode waves could provide a viable mechanism for stochastic energization of electrons with energies up to 50 MeV in the Jovian magnetosphere.

  6. 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 compared with the profiles obtained from the shock tube. To conclude, our experimental results demonstrate that a compressed-gas shock tube when designed and operated carefully can replicate the blast time profiles of field explosions accurately. Such a faithful replication is an essential first step when studying the effects of blast induced neurotrauma using animal models. PMID:25520701

  7. A study of ambient upstream material properties using perpendicular laser driven radiative blast waves in atomic cluster gases

    NASA Astrophysics Data System (ADS)

    Olsson Robbie, S. I.; Doyle, H. W.; Symes, D. R.; Smith, R. A.

    2012-03-01

    We report on the characterisation of the upstream medium ahead of a radiative cylindrical blast wave launched in an argon cluster gas with a 1 J, 1 ps, 1054 nm Nd:Glass laser system. By launching two perpendicular blast waves and introducing a time delay between the heating beams it is possible to determine the extent of the cluster medium by observing the high energy absorption region associated with clusters, as apposed to the low energy deposition in monatomic gas. It was found that argon ions launched from the initial laser driven cluster ionisation created a ballistic ion wave which sweeps out ahead of the hydrodynamic blast wave at an initial velocity of 1000 kms -1. This ballistic wave disassembles the clusters ahead of the blast wave into a neutral gas medium before the arrival of a radiative precursor. This observation gives us confidence that the dynamics of a radiative blast wave in cluster based experiments is determined primarily by the properties of an upstream atomic gas, and is not significantly influenced by cluster affects on energy transport or other material properties.

  8. Drift resonant generation of peaked relativistic electron distributions by Pc 5 ULF waves

    Microsoft Academic Search

    A. W. Degeling; L. G. Ozeke; R. Rankin; I. R. Mann; K. Kabin

    2008-01-01

    The adiabatic drift-resonant interaction between relativistic, equatorially mirroring electrons and narrowband, Pc 5 ultra low frequency (ULF) waves in the magnetosphere is investigated using a time-dependent magnetohydrodynamic (MHD) wave model. Attention is focused on the effect of a ULF wave packet with finite duration on the equatorially mirroring, relativistic electron phase space density (PSD) profile. It is demonstrated that a

  9. An approximate theory of electromagnetic wave propagation in a weakly relativistic plasma

    Microsoft Academic Search

    S. S. Sazhin

    1987-01-01

    An approximate analysis of different types of electromagnetic wave propagation in a weakly relativistic electron plasma is presented. The particular case of wave propagation near the cold plasma cut-offs is considered, and possible applications of the results to diagnostics of magnetospheric parameters are discussed. It is pointed out that wave propagation near plasma resonances in some cases requires relativistic consideration,

  10. Effect of shock wave on fabricated anti-blast wall and distribution law around the wall under near surface explosion

    Microsoft Academic Search

    Jun Wu; Jingbo Liu; Qiushi Yan

    2008-01-01

    The loads of shock wave effect on fabricated anti-blast wall and distribution law around the wall were investigated by using\\u000a near surface explosion test method and FEM. The pressure-time histories and variety law on the foreside and backside of the\\u000a anti-blast wall were adopted in the tests of variety of different explosion distances and dynamites, as well as in the

  11. Application of blast wave theory to explosive propulsion. [system performance analysis

    NASA Technical Reports Server (NTRS)

    Back, L. H.

    1975-01-01

    An analysis was carried out by using blast wave theory to delineate the important aspects of detonating explosives in nozzles, such as flow and wave phenomena, characteristic length and time scales, and the parameters on which the specific impulse is dependent. The propulsive system utilizes the momentum of the ambient gas set into motion in the nozzle by the explosion. A somewhat simplified model was considered for the situation where the mass of ambient gas in the nozzle is much greater than the mass of gas produced in the explosion, a condition of interest for dense atmospheres, e.g., near the surface of Venus. Instantaneous detonation and energy release was presumed to occur at the apex of a conical nozzle, and the shock wave generated by the explosion was taken to propagate as a spherical wave, thereby setting the ambient gas in the nozzle into one-dimensional radially outward motion.

  12. EFFECT OF INTERACTING RAREFACTION WAVES ON RELATIVISTICALLY HOT JETS

    SciTech Connect

    Matsumoto, Jin; Shibata, Kazunari [Kwasan and Hida Observatories, Kyoto University, Kyoto (Japan); Masada, Youhei, E-mail: jin@kusastro.kyoto-u.ac.jp [Graduate School of System Informatics, Department of Computational Science, Kobe University, Kobe (Japan)

    2012-06-01

    The effect of rarefaction acceleration on the propagation dynamics and structure of relativistically hot jets is studied through relativistic hydrodynamic simulations. We emphasize the nonlinear interaction of rarefaction waves excited at the interface between a cylindrical jet and the surrounding medium. From simplified one-dimensional (1D) models with radial jet structure, we find that a decrease in the relativistic pressure due to the interacting rarefaction waves in the central zone of the jet transiently yields a more powerful boost of the bulk jet than that expected from single rarefaction acceleration. This leads to a cyclic in situ energy conversion between thermal and bulk kinetic energies, which induces radial oscillating motion of the jet. The oscillation timescale is characterized by the initial pressure ratio of the jet to the ambient medium and follows a simple scaling relation, {tau}{sub oscillation}{proportional_to}(P{sub jet,0}/P{sub amb,0}){sup 1/2}. Extended two-dimensional simulations confirm that this radial oscillating motion in the 1D system manifests as modulation of the structure of the jet in a more realistic situation where a relativistically hot jet propagates through an ambient medium. We find that when the ambient medium has a power-law pressure distribution, the size of the reconfinement region along the propagation direction of the jet in the modulation structure {lambda} evolves according to a self-similar relation {lambda}{proportional_to}t{sup {alpha}/2}, where {alpha} is the power-law index of the pressure distribution.

  13. PeV-EeV neutrinos from GRB blast waves in IceCube and future neutrino telescopes

    NASA Astrophysics Data System (ADS)

    Razzaque, Soebur; Yang, Lili

    2015-02-01

    Ultrahigh-energy cosmic rays (UHECRs), if accelerated in the gamma-ray burst (GRB) blast wave, are expected to produce PeV-EeV neutrinos by interacting with long-lived GRB afterglow photons. Detailed spectral and temporal properties of the flux of these neutrinos depend on the GRB blast wave evolution scenario, but can last for days to years time scale in contrast to the seconds to minutes time scale for "burst" neutrino flux contemporaneous with the prompt gamma-ray emission and which has been constrained by IceCube in the ˜50 TeV -2 PeV range. We compute expected neutrino events in IceCube in the PeV-EeV range from the blast wave of long-duration GRBs, both for the diffuse flux and for individual GRBs in the nearby universe. We show that IceCube will be able to detect the diffuse GRB blast wave neutrino flux after 5 years in operation, and will be able to distinguish it from the cosmogenic neutrino flux arising from the Greisen-Zatsepin-Kuzmin process in case the ultrahigh-energy cosmic rays are heavy nuclei. We also show that EeV neutrinos from the blast wave of an individual GRB can be detected with long-term monitoring by a future high-energy extension of IceCube for redshift up to z ˜0.5 .

  14. Blast-Associated Shock Waves Result in Increased Brain Vascular Leakage and Elevated ROS Levels in a Rat Model of Traumatic Brain Injury

    PubMed Central

    Petro, Marianne; Dudzinski, Dave; Stewart, Desiree; Courtney, Amy; Courtney, Michael; Labhasetwar, Vinod

    2015-01-01

    Blast-associated shock wave-induced traumatic brain injury (bTBI) remains a persistent risk for armed forces worldwide, yet its detailed pathophysiology remains to be fully investigated. In this study, we have designed and characterized a laboratory-scale shock tube to develop a rodent model of bTBI. Our blast tube, driven by a mixture of oxygen and acetylene, effectively generates blast overpressures of 20–130 psi, with pressure-time profiles similar to those of free-field blast waves. We tested our shock tube for brain injury response to various blast wave conditions in rats. The results show that blast waves cause diffuse vascular brain damage, as determined using a sensitive optical imaging method based on the fluorescence signal of Evans Blue dye extravasation developed in our laboratory. Vascular leakage increased with increasing blast overpressures and mapping of the brain slices for optical signal intensity indicated nonhomogeneous damage to the cerebral vasculature. We confirmed vascular leakage due to disruption in the blood-brain barrier (BBB) integrity following blast exposure. Reactive oxygen species (ROS) levels in the brain also increased with increasing blast pressures and with time post-blast wave exposure. Immunohistochemical analysis of the brain sections analyzed at different time points post blast exposure demonstrated astrocytosis and cell apoptosis, confirming sustained neuronal injury response. The main advantages of our shock-tube design are minimal jet effect and no requirement for specialized equipment or facilities, and effectively generate blast-associated shock waves that are relevant to battle-field conditions. Overall data suggest that increased oxidative stress and BBB disruption could be the crucial factors in the propagation and spread of neuronal degeneration following blast injury. Further studies are required to determine the interplay between increased ROS activity and BBB disruption to develop effective therapeutic strategies that can prevent the resulting cascade of neurodegeneration. PMID:26024446

  15. Generalized Relativistic Wave Equations with Intrinsic Maximum Momentum

    E-print Network

    Chee Leong Ching; Wei Khim Ng

    2013-11-15

    We examine the nonperturbative effect of maximum momentum on the relativistic wave equations. In momentum representation, we obtain the exact eigen-energies and wavefunctions of one-dimensional Klein-Gordon and Dirac equation with linear confining potentials, and the Dirac oscillator. Bound state solutions are only possible when the strength of scalar potential are stronger than vector potential. The energy spectrum of the systems studied are bounded from above, whereby classical characteristics are observed in the uncertainties of position and momentum operators. Also, there is a truncation in the maximum number of bound states that is allowed. Some of these quantum-gravitational features may have future applications.

  16. Relativistic focusing and beat wave phase velocity control in the plasma beat wave accelerator

    Microsoft Academic Search

    E. Esarey; A. Ting; P. Sprangle

    1988-01-01

    Relativistic focusing allows two collinear short pulse radiation beams, provided they are of sufficiently high power, to propagate through a plasma without diffracting. By further accounting for finite radial beam geometry, it is possible for the phase velocity of the radiation beat (ponderomotive) wave to equal to the speed of light. This removes one of the limiting factors, phase detuning

  17. Relativistic focusing and beat wave phase velocity control in the plasma beat wave accelerator

    Microsoft Academic Search

    E. Esarey; A. Ting; P. Sprangle

    1988-01-01

    Relativistic focusing allows two colinear short pulse radiation beams, provided they are of sufficiently high power, to propagate through a plasma without diffracting. By further accounting for finite radial beam geometry, it is possible for the phase velocity of the radiation beat (ponderomotive) wave to equal the speed of light. This removes one of the limiting factors, phase detuning between

  18. Superheterodyne amplification of electromagnetic waves in a system of two relativistic electron flows

    Microsoft Academic Search

    O. N. Bolonin; V. V. Kulish; V. P. Pugachev

    1988-01-01

    The dynamics of two relativistic electron beams in the presence of two transverse electromagnetic waves is examined for the case where one of the waves is an amplified (generated) electromagnetic wave (signal), such as an optical wave, and the other is a low-frequency electromagnetic wave or a periodically reversing magnetostatic field (wiggler). The problem is solved in the weak signal

  19. The Blast-Wave-Driven Instability as a Vehicle for Understanding Supernova Explosion Structure

    SciTech Connect

    Miles, A R

    2008-05-27

    Blast-wave-driven instabilities play a rich and varied role throughout the evolution of supernovae from explosion to remnant, but interpreting their role is difficult due to the enormous complexity of the stellar systems. We consider the simpler and fundamental hydrodynamic instability problem of a material interface between two constant-density fluids perturbed from spherical and driven by a divergent central Taylor-Sedov blast wave. The existence of unified solutions at high Mach number and small density ratio suggests that general conclusions can be drawn about the likely asymptotic structure of the mixing zone. To this end we apply buoyancy-drag and bubble merger models modified to include the effects of divergence and radial velocity gradients. In general, these effects preclude the true self-similar evolution of classical Raleigh-Taylor, but can be incorporated into a quasi-self-similar growth picture. Loss of memory of initial conditions can occur in the quasi-self-similar model, but requires initial mode numbers higher than those predicted for pre-explosion interfaces in Type II SNe, suggesting that their late-time structure is likely strongly influenced by details of the initial perturbations. Where low-modes are dominant, as in the Type Ia Tycho remnant, they result from initial perturbations rather than generation from smaller scales. Therefore, structure observed now contains direct information about the explosion process. When large-amplitude modes are present in the initial conditions, the contribution to the perturbation growth from the Richtmyer-Meshkov instability is significant or dominant compared to Rayleigh-Taylor. Such Richtmyer-Meshkov growth can yield proximity of the forward shock to the growing spikes and structure that strongly resembles that observed in the Tycho. Laser-driven high-energy-density laboratory experiments offer a promising avenue for testing model and simulation descriptions of blast-wave-driven instabilities and making connections to their astrophysical counterparts.

  20. Modeling and simulation of blast-induced, early-time intracranial wave physics leading to traumatic brain injury.

    SciTech Connect

    Ford, Corey C. (University of New Mexico, Albuquerque, NM); Taylor, Paul Allen

    2008-02-01

    The objective of this modeling and simulation study was to establish the role of stress wave interactions in the genesis of traumatic brain injury (TBI) from exposure to explosive blast. A high resolution (1 mm{sup 3} voxels), 5 material model of the human head was created by segmentation of color cryosections from the Visible Human Female dataset. Tissue material properties were assigned from literature values. The model was inserted into the shock physics wave code, CTH, and subjected to a simulated blast wave of 1.3 MPa (13 bars) peak pressure from anterior, posterior and lateral directions. Three dimensional plots of maximum pressure, volumetric tension, and deviatoric (shear) stress demonstrated significant differences related to the incident blast geometry. In particular, the calculations revealed focal brain regions of elevated pressure and deviatoric (shear) stress within the first 2 milliseconds of blast exposure. Calculated maximum levels of 15 KPa deviatoric, 3.3 MPa pressure, and 0.8 MPa volumetric tension were observed before the onset of significant head accelerations. Over a 2 msec time course, the head model moved only 1 mm in response to the blast loading. Doubling the blast strength changed the resulting intracranial stress magnitudes but not their distribution. We conclude that stress localization, due to early time wave interactions, may contribute to the development of multifocal axonal injury underlying TBI. We propose that a contribution to traumatic brain injury from blast exposure, and most likely blunt impact, can occur on a time scale shorter than previous model predictions and before the onset of linear or rotational accelerations traditionally associated with the development of TBI.

  1. Blast wave in a nozzle for propulsive applications

    NASA Technical Reports Server (NTRS)

    Varsi, G.; Back, L. H.; Kim, K.

    1976-01-01

    The reported investigation has been conducted in connection with studies concerning the development of a propulsion system based on the use of a detonating fluid propellant. Measurements have been made of the pressure and shock wave velocity in a conical nozzle at various ambient pressures and at an ambient temperature of 25 C. In the experiments a small amount of explosive was placed at the end wall of a conical aluminum nozzle and detonated by a microdetonator inside the nozzle. Differences regarding the characteristics of conventional chemical propulsion and detonation propulsion are illustrated with the aid of a graph. One- and two-dimensional numerical flow calculations were performed and compared with the experimental data.

  2. Mathematical theory of cylindrical isothermal blast waves in a magnetic field. [with application to supernova remnant evolution

    NASA Technical Reports Server (NTRS)

    Lerche, I.

    1981-01-01

    An analysis is conducted regarding the properties of cylindrically symmetric self-similar blast waves propagating away from a line source into a medium whose density and magnetic field (with components in both the phi and z directions) both vary as r to the -(omega) power (with omega less than 1) ahead of the blast wave. The main results of the analysis can be divided into two classes, related to a zero azimuthal field and a zero longitudinal field. In the case of the zero longitudinal field it is found that there are no physically acceptable solutions with continuous postshock variations of flow speed and gas density.

  3. Influence of the forward wave on the efficiency of generating microwave radiation in a relativistic backward wave tube

    Microsoft Academic Search

    S. D. Korovin; S. D. Polevin; A. M. Roitman; V. V. Rostov; L. D. Moreland; E. Schamiloglu

    1996-01-01

    An analysis is made of the influence of the forward wave on the operation of a relativistic uniform backward wave tube. The conditions are determined under which it is necessary to take account of asynchronous waves in the processes of energy exchange between the electromagnetic field and the electron beam. It is shown that the forward wave can strongly influence

  4. Relativistic plasma microwave electronics: studies of high power plasma filled backward wave oscillators

    Microsoft Academic Search

    Y. Carmel; W. R. Lou; J. Rodgers; B. Levush; J. Tate; W. W. Destler; V. L. Granatstein

    1992-01-01

    Summary form only given, as follows. The area of relativistic plasma microwave electronics has recently generated renewed interest in the microwave and millimeter-wave device community. The authors have obtained experimental data demonstrating that the presence of a low-density background plasma in a relativistic backward wave oscillator leads to several beneficial effects, including enhanced interaction efficiency (40%), operation at very low

  5. Massless and Massive Gauge-Invariant Fields in the Theory of Relativistic Wave Equations

    E-print Network

    V. A. Pletyukhov; V. I. Strazhev

    2010-02-03

    In this work consideration is given to massless and massive gauge-invariant spin 0 and spin 1 fields (particles) within the scope of a theory of the generalized relativistic wave equations with an extended set of the Lorentz group representations. The results obtained may be useful as regards the application of a relativistic wave-equation theory in modern field models.

  6. Nonlinear Interaction of Relativistic Electrons and Electromagnetic Ion Cyclotron Waves in a Two-wave Model

    NASA Astrophysics Data System (ADS)

    An, X.; Chen, L.; Bortnik, J.; Thorne, R. M.

    2013-12-01

    Nonlinear interaction of relativistic electrons with a monochromatic electromagnetic ion cyclotron wave was investigated extensively in previous studies. Here we extend this work to investigate wave particle interactions in a two-wave model. By varying the separation of the two wave numbers, we calculate the Chirikov parameter, which measures the degree of the overlap of the resonant islands in the phase portrait. We demonstrate that the resonant islands highly overlap over a large range of the wave number separation, depending on which three typical regimes are identified. 1) a degenerate regime in which the effect of the two waves can be approximated by one wave model; 2) a transition regime where the resonant latitude of one wave moves equatorward and finally drops out of resonance with the electrons; 3) a non-overlap region where one wave is resonant with the electrons and the other is not. In the degenerate region, the concepts from the single wave interaction, i.e., phase bunching and phase trapping, still apply. When the particle initial pitch angle or the wave amplitude decreases, the length of the range of the degenerate region increases. In the transition region, the motions of the electrons are stochastic. In the non-overlap region, only the resonant wave is responsible for the electron scattering while the nonresonant wave contributes little. As one important application in the realistic space environment, we demonstrate that EMIC wave interactions with electrons can be treated by a single wave if the range of wave frequencies is located inside the degenerate region.

  7. Interaction and coalescence of multiple simultaneous and non-simultaneous blast waves

    NASA Astrophysics Data System (ADS)

    Qiu, S.; Eliasson, V.

    2015-04-01

    Interaction of multiple blast waves can be used to direct energy toward a target while simultaneously reducing collateral damage away from the target area. In this paper, simulations of multiple point source explosives were performed and the resulting shock interaction and coalescence behavior were explored. Three to ten munitions were placed concentrically around the target, and conditions at the target area were monitored and compared to those obtained using a single munition. For each simulation, the energy summed over all munitions was kept constant, while the radial distances between target and munitions and the munition initiation times were varied. Each munition was modeled as a point source explosion. The resulting blast wave propagation and shock front coalescence were solved using the inviscid Euler equations of gas dynamics on overlapping grids employing a finite difference scheme. Results show that multiple munitions can be beneficial for creating extreme conditions at the intended target area; over 20 times higher peak pressure is obtained for ten simultaneous munitions compared to a single munition. Moreover, peak pressure at a point away from the target area is reduced by more than a factor of three.

  8. Accelerated dynamics of blast wave driven Rayleigh-Taylor instabilities in high energy density plasmas

    NASA Astrophysics Data System (ADS)

    Swisher, N.; Kuranz, C.; Drake, R. P.; Abarzhi, S. I.

    2014-10-01

    We report the systematic analysis of experimental data describing the late time evolution of the high Mach number and high Reynolds number Rayleigh-Taylor instability which is driven by a blast wave. The parameter regime is relevant to high energy density plasmas and astrophysics. The experiments have been conducted at the Omega laser facility. By processing the experimental x-ray images, we quantified the delicate features of RT dynamics, including the measurements of the curvature of the transmitted shock and the interface envelopes, the positions of RT bubbles and spikes, and the quantification of statistics of RT mixing. The measurements were performed at four time steps and for three different initial perturbations of the target (single mode and two two-mode). We found that within the noise level the curvatures of the shock and interface envelope evolve steadily and are an imprint of laser imperfections. At late times, the bubble merge does not occur, and the flow keeps significant degree of order. Yet, the blast-wave-driven RT spikes do accelerate with the power-law exponent smaller than that in case of sustained acceleration. We compared the experimental results with the momentum model of RT mixing and stochastic model achieving good agreement. The work is supported by the US National Science Foundation.

  9. Blast wave radiation source measurement experiments on the Z Z-pinch facility

    SciTech Connect

    Peterson, R.R.; Peterson, D.L.; Watt, R.G.; Idzorek, G.; Tierney, T.; Lopez, M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2006-05-15

    The Dynamic Hohlraum (DH) radiation on the Z facility at Sandia National Laboratories [R. B. Spielman, W. A. Stygar, J. F. Seamen et al., Proceeding of the 11th International Pulsed Power Conference, Baltimore, 1997, edited by G. Cooperstein and I. Vitkovitsky (IEEE, Piscataway, NJ, 1997), Vol. 1, p. 709] is a bright source of radiant energy that has proven useful for high energy density physics experiments. But the radiation output from a DH on Z needs to be well known. In this paper, a new method is presented for measuring the radiation fluence deposited in an experiment, specifically, an experiment driven by a Z DH. This technique uses a blast wave produced in a SiO{sub 2} foam, which starts as supersonic but transitions to subsonic, producing a shock at the transition point that is observable via radiography. The position of this shock is a sensitive measure of the radiation drive energy from the Z DH. Computer simulations have been used to design and analyze a Z foam blast wave experiment.

  10. TWO-DIMENSIONAL BLAST-WAVE-DRIVEN RAYLEIGH-TAYLOR INSTABILITY: EXPERIMENT AND SIMULATION

    SciTech Connect

    Kuranz, C. C.; Drake, R. P.; Harding, E. C.; Grosskopf, M. J. [University of Michigan, MI (United States); Robey, H. F.; Remington, B. A.; Edwards, M. J.; Miles, A. R.; Perry, T. S. [Lawrence Livermore National Laboratory, University of California, P.O. Box 5508, L-487, Livermore, CA 94550 (United States); Blue, B. E. [General Atomics, San Diego, CA (United States); Plewa, T. [Department of Scientific Computing, Florida State University, Dirac Science Library Tallahassee, FL 32306-4120 (United States); Hearn, N. C. [ASC/Alliances Center for Astrophysical Thermonuclear Flashes, University of Chicago, IL (United States); Knauer, J. P. [Laboratory of Laser Energetics, University of Rochester, Rochester, NY (United States); Arnett, D. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Leibrandt, D. R. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2009-05-01

    This paper shows results from experiments diagnosing the development of the Rayleigh-Taylor instability with two-dimensional initial conditions at an embedded, decelerating interface. Experiments are performed at the Omega Laser and use {approx}5 kJ of energy to create a planar blast wave in a dense, plastic layer that is followed by a lower density foam layer. The single-mode interface has a wavelength of 50 {mu}m and amplitude of 2.5 {mu}m. Some targets are supplemented with additional modes. The interface is shocked then decelerated by the foam layer. This initially produces the Richtmyer-Meshkov instability followed and then dominated by Rayleigh-Taylor growth that quickly evolves into the nonlinear regime. The experimental conditions are scaled to be hydrodynamically similar to SN1987A in order to study the instabilities that are believed to occur at the He/H interface during the blast-wave-driven explosion phase of the star. Simulations of the experiment were performed using the FLASH hydrodynamics code.

  11. Laboratory observation of secondary shock formation ahead of a strongly radiative blast wave

    SciTech Connect

    Hansen, J.F.; Edwards, M.J.; Froula, D.H.; Gregori, G.; Edens, A.D.; Ditmire, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); LRC-Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); University of Texas at Austin, Austin, Texas 78712 (United States)

    2006-02-15

    High Mach number blast waves were created by focusing a laser pulse on a solid pin, surrounded by nitrogen or xenon gas. In xenon, the initial shock is strongly radiative, sending out a supersonic radiative heat wave far ahead of itself. The shock propagates into the heated gas, diminishing in strength as it goes. The radiative heat wave also slows, and when its Mach number drops to two with respect to the downstream plasma, the heat wave drives a second shock ahead of itself to satisfy mass and momentum conservation in the heat wave reference frame; the heat wave becomes subsonic behind the second shock. For some time both shocks are observed simultaneously. Eventually the initial shock diminishes in strength so much that it can longer be observed, but the second shock continues to propagate long after this time. This sequence of events is a new phenomenon that has not previously been discussed in the literature. Numerical simulation clarifies the origin of the second shock, and its position is consistent with an analytical estimate.

  12. Blast Waves and Explosions Sound generation by explosive decompression of an airplane

    NASA Astrophysics Data System (ADS)

    Shepherd, J. E.; Hornung, H. G.

    We examine sound generation by the explosive decompression of a pressurized airplane in flight. The near-field is numerically computed by assuming the sudden removal of an axial section of an idealized, streamlined, cylindrical fuselage with an external flow simulating flight. After an initial transient period, we find a nearly circular blast wave with a leading shock strength that is highest in the direction of motion and decreasing rapidly as the observer moves to the rear of the airplane. Geometric acoustics (ray tracing) is used to estimate the attenuation of the wave as it propagates through a model atmosphere to observers on the ground. The audibility of the event is examined in the case of the TWA 800 accident and compared to previous analyses.

  13. Computational Study of Thrust Generation from Laser-Driven Blast Wave

    SciTech Connect

    Ohnishi, Naofumi [Center for Research Strategy and Support, Tohoku University, Sendai 980-8579 (Japan); Department of Aerospace Engineering, Tohoku University, Sendai 980-8579 (Japan); Ogino, Yousuke [Department of Aerospace Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2008-04-28

    We have performed axisymmetric simulations in order to investigate the thrust generation resulting from the interference between the projectile and the blast wave produced by a pulsed laser. The results obtained by our numerical code well agree for the pressure history and the momentum coupling coefficient with the experimental data. In such analysis, it is found that the approximate impulse estimated only by the pressure history at the projectile base is difficult to predict the actual one. Since the shock wave rapidly attenuates in low fill pressure, and the interaction with the projectile almost finishes in the shroud, a high momentum coupling coefficient can be achieved unlike the case of high fill pressure in which the projectile experiences the subsequent negative thrust.

  14. Numerical study of contributions of shock wave and gas penetration toward induced rock damage during blasting

    NASA Astrophysics Data System (ADS)

    Lanari, M.; Fakhimi, A.

    2015-06-01

    The authors present an improved version of continuum analysis 2D, a hybrid two-dimensional finite element-discrete element-smoothed particle program for modeling rock blasting. A modified formula governing the interaction of smoothed particles with discrete elements is presented, along with the results of numerical simulations involving detonations within jointed rock. PETN was modeled as the explosive, and Barre granite as the rock specimen. The borehole was simulated both with and without a thin copper lining. The purpose of the copper lining is to prevent gas from penetrating into the induced cracks within the rock, so that the shock wave's contribution toward rock damage can be separated from that of the gas penetration. The results suggest that majority of the cracks are formed due to the shock wave propagating within the rock, whereas the gas penetration mostly separates the already-formed rock fragments and pushes them apart.

  15. Fluid/Structure Interaction Computational Investigation of Blast-Wave Mitigation Efficacy of the Advanced Combat Helmet

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Bell, W. C.; Pandurangan, B.; Glomski, P. S.

    2011-08-01

    To combat the problem of traumatic brain injury (TBI), a signature injury of the current military conflicts, there is an urgent need to design head protection systems with superior blast/ballistic impact mitigation capabilities. Toward that end, the blast impact mitigation performance of an advanced combat helmet (ACH) head protection system equipped with polyurea suspension pads and subjected to two different blast peak pressure loadings has been investigated computationally. A fairly detailed (Lagrangian) finite-element model of a helmet/skull/brain assembly is first constructed and placed into an Eulerian air domain through which a single planar blast wave propagates. A combined Eulerian/Lagrangian transient nonlinear dynamics computational fluid/solid interaction analysis is next conducted in order to assess the extent of reduction in intra-cranial shock-wave ingress (responsible for TBI). This was done by comparing temporal evolutions of intra-cranial normal and shear stresses for the cases of an unprotected head and the helmet-protected head and by correlating these quantities with the three most common types of mild traumatic brain injury (mTBI), i.e., axonal damage, contusion, and subdural hemorrhage. The results obtained show that the ACH provides some level of protection against all investigated types of mTBI and that the level of protection increases somewhat with an increase in blast peak pressure. In order to rationalize the aforementioned findings, a shockwave propagation/reflection analysis is carried out for the unprotected head and helmet-protected head cases. The analysis qualitatively corroborated the results pertaining to the blast-mitigation efficacy of an ACH, but also suggested that there are additional shockwave energy dissipation phenomena which play an important role in the mechanical response of the unprotected/protected head to blast impact.

  16. Whistler wave generation by non-gyrotropic, relativistic, electron beams

    NASA Astrophysics Data System (ADS)

    Skender, Marina; Tsiklauri, David

    2014-05-01

    Super-thermal electron beams travelling away from the Sun on the open magnetic field lines are widely accepted to be the source of the Type-III bursts. The earliest idea of the generation of the Type-III bursts was based on the plasma emission mechanism. A fast moving electron beam excites Langmuir waves at the local plasma frequency, ?p. The Langmuir waves are partially transformed via scattering at ?p and 2?p, with ion sound and oppositely propagating Langmuir waves, respectively, into electromagnetic waves. As the electron beam propagates away from the Sun, through less dense coronal and interplanetary environment, the frequency of the emitted electromagnetic radiation decreases, because plasma frequency is a function of the square root of the plasma density. Type-III bursts have been subject of theoretical, observational and numerical studies. The first detailed theory of the Type-III emission invoked coherent plasma waves, generated by a stream of fast particles, which are due to Rayleigh and combination scattering at ?p and 2?p subsequently transformed into radio waves. Stochastic growth of the density irregularities was invoked in order to produce stochastically generated clumpy Langmuir waves, where the ambient density perturbations cause the beam to fluctuate around marginal stability. Other theories on the mechanism which generates the Type-III emission include: linear mode conversion of Langmuir waves, Langmuir waves producing electromagnetic radiation as antennas and non-gyroptropic electron beam emission [1] of commensurable properties to the Type-III bursts. In Refs. [2,3] it was found that the non-gyrotropic beam excites electromagnetic radiation by the current transverse to the magnetic field, which results in (?,k)-space drift while propagating along the 1-dimensional spatial domain throughout the decreasing plasma density profile. The role of the electron beam pitch angle and the background density gradient profile was investigated in [4]. In this study [5], for the first time, the backwards propagating wave component evident in the perpendicular components of the electromagnetic field in such a system is presented. Features of the wave component propagating backwards from the front of the non-gyrotropic, relativistic, beam of electrons injected in the Maxwellian, magnetised background plasma with decreasing density profile are studied by using the Particle-In-Cell code EPOCH. Magnetic field in the 1.5-dimensional system is varied in order to prove that the backwards propagating wave is harmonic of the electron cyclotron frequency. The analysis has lead to the identification of the backwards travelling waves as whistlers. Moreover, the whistlers are shown to be generated by the normal and anomalous Doppler resonance. Large fraction of the energy of the perpendicular electromagnetic field components is found to be carried away by the whistler waves. [1] D. Tsiklauri, Phys. Plasmas 18, 052903 (2011). [2] D. Tsiklauri, H. Schmitz, Geophys. Res. Abs. 15, EGU2013-5403 (2013). [3] H. Schmitz, D. Tsiklauri, Phys. Plasmas 20, 062903 (2013). [4] R. Pechhacker, D. Tsiklauri, Phys. Plasmas 19, 112903 (2012). [5] M. Skender, D. Tsiklauri, submitted to Phys. Plasmas (2013): http://astro.qmul.ac.uk/ tsiklauri/

  17. Theory manual to OctVCE - a cartesian cell CFD code with special application to blast wave problems

    Microsoft Academic Search

    Joseph Tang

    2007-01-01

    Abstract OctVCE is a cartesian cell CFD code produced especially for numerical simulations of shock and blast wave interactions with complex geometries, in particular, from explosions. Virtual Cell Embedding (VCE) was chosen as its cartesian cell kernel for its simplicity and suciency for practical engineering design problems. The code uses a finite-volume formulation of the unsteady Euler equations with a

  18. Brain Response to Primary Blast Wave Using Validated Finite Element Models of Human Head and Advanced Combat Helmet

    PubMed Central

    Zhang, Liying; Makwana, Rahul; Sharma, Sumit

    2013-01-01

    Blast-induced traumatic brain injury has emerged as a “signature injury” in combat casualty care. Present combat helmets are designed primarily to protect against ballistic and blunt impacts, but the current issue with helmets is protection concerning blasts. In order to delineate the blast wave attenuating capability of the Advanced Combat Helmet (ACH), a finite element (FE) study was undertaken to evaluate the head response against blast loadings with and without helmet using a partially validated FE model of the human head and ACH. Four levels of overpressures (0.27–0.66?MPa) from the Bowen’s lung iso-damage threshold curves were used to simulate blast insults. Effectiveness of the helmet with respect to head orientation was also investigated. The resulting biomechanical responses of the brain to blast threats were compared for human head with and without the helmet. For all Bowen’s cases, the peak intracranial pressures (ICP) in the head ranged from 0.68 to 1.8?MPa in the coup cortical region. ACH was found to mitigate ICP in the head by 10–35%. Helmeted head resulted in 30% lower average peak brain strains and product of strain and strain rate. Among three blast loading directions with ACH, highest reduction in peak ICP (44%) was due to backward blasts whereas the lowest reduction in peak ICP and brain strains was due to forward blast (27%). The biomechanical responses of a human head to primary blast insult exhibited directional sensitivity owing to the different geometry contours and coverage of the helmet construction and asymmetric anatomy of the head. Thus, direction-specific tolerances are needed in helmet design in order to offer omni-directional protection for the human head. The blasts of varying peak overpressures and durations that are believed to produce the same level of lung injury produce different levels of mechanical responses in the brain, and hence “iso-damage” curves for brain injury are likely different than the Bowen curves for lung injury. PMID:23935591

  19. Numerical simulation of laser--target interaction and blast wave formation

    SciTech Connect

    Giuliani, J. L., Jr.; Mulbrandon, M.; Hyman, E.

    1989-07-01

    A numerical hydrodynamics chemistry model to simulate the laser--targetinteraction experiment at the Naval Research Laboratory's PHAROS(/ital Laser//nteraction/ /ital and//elated/ /ital Plasma//henomena/ (Plenum, New York, 1986), Vol. 7,p. 857) is presented. Both laser--target and debris--background interactionsare modeled, solving mass continuity, total momentum, and separate ion andelectron internal energy equations. The model is appropriate for backgrounddensitiesgreater than or equal to1 Torr. To accurately treat both the early-time planar ablation andthe later spherical expansion of the blast wave, as well as the rear-side shockfront, an oblate spheroidal coordinate system was adopted. The aluminum targetablates into and interacts with an ambient nitrogen gas, filling the facilitychamber. The simulation models the target continuously from the solid state tothe state of a highly ionized nonequilibrium plasma, including all charge statesof aluminum and all charge states of the nitrogen background. The laser beam hasa wavelength of 1 ..mu.., a /similar to/5 nsec full width at half-maximum (FWHM), anintensity at the target surface /similar to/10/sup 13/ W/cm/sup 2/, and total energy varyingfrom 20--100 J. The model accurately reproduces the measured time-of-flightprofile and the mass of ablated aluminum. Expansion of the blast wave in themodel follows the ideal Sedov relation until radiation losses force a deviationdue to a failure in the constant energy assumption. In the shock wave region thesimulations show electron density of a few times 10/sup 18/ cm/sup /minus/3/, temperaturesranging from 10--20 eV, and dominant nitrogen species of N/sup +3/ and N/sup +4/,all in agreement with experimental measurement.

  20. A repetitive 0.14 THz relativistic surface wave oscillator

    SciTech Connect

    Wang Guangqiang; Tong Changjiang; Li Xiaoze; Wang Xuefeng; Li Shuang; Lu Xicheng [Northwest Institute of Nuclear Technology, P.O. Box 69-1, Xi'an 710024 (China); Wang Jianguo [Northwest Institute of Nuclear Technology, P.O. Box 69-1, Xi'an 710024 (China); School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049 (China)

    2013-04-15

    Preliminary experimental results of a repetitive 0.14 THz overmoded relativistic surface wave oscillator (RSWO) are presented in this paper. The repetitive RSWO is developed by using a rectangularly corrugated slow-wave structure with overmoded ratio of 3 and a foilless diode emitting annular electron beam with thickness of 0.5 mm. The high quality electron beams at the repetition rate of 10 are obtained over a wide range of diode voltage (180 kV < U < 240 kV) and current (700 A < I < 1.2 kA). The generation experiments of RSWO are conducted at an axial pulsed magnetic field whose maximum strength and duration can reach about 2.7 T and 1 s, respectively. The experimental results show that the RSWO successfully produces reasonable uniform terahertz pulses at repetition rate of 10, and the pulse duration, frequency, and power of a single pulse are about 1.5 ns, 0.154 THz, and 2.6 MW, respectively, whereas the dominated radiation mode of the RSWO is TM{sub 02}.

  1. ELECTRON INJECTION BY WHISTLER WAVES IN NON-RELATIVISTIC SHOCKS

    SciTech Connect

    Riquelme, Mario A. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Spitkovsky, Anatoly, E-mail: marh@astro.berkeley.edu, E-mail: anatoly@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2011-05-20

    Electron acceleration to non-thermal, ultra-relativistic energies ({approx}10-100 TeV) is revealed by radio and X-ray observations of shocks in young supernova remnants (SNRs). The diffusive shock acceleration (DSA) mechanism is usually invoked to explain this acceleration, but the way in which electrons are initially energized or 'injected' into this acceleration process starting from thermal energies is an unresolved problem. In this paper we study the initial acceleration of electrons in non-relativistic shocks from first principles, using two- and three-dimensional particle-in-cell (PIC) plasma simulations. We systematically explore the space of shock parameters (the Alfvenic Mach number, M{sub A} , the shock velocity, v{sub sh}, the angle between the upstream magnetic field and the shock normal, {theta}{sub Bn}, and the ion to electron mass ratio, m{sub i} /m{sub e} ). We find that significant non-thermal acceleration occurs due to the growth of oblique whistler waves in the foot of quasi-perpendicular shocks. This acceleration strongly depends on using fairly large numerical mass ratios, m{sub i} /m{sub e} , which may explain why it had not been observed in previous PIC simulations of this problem. The obtained electron energy distributions show power-law tails with spectral indices up to {alpha} {approx} 3-4. The maximum energies of the accelerated particles are consistent with the electron Larmor radii being comparable to that of the ions, indicating potential injection into the subsequent DSA process. This injection mechanism, however, requires the shock waves to have fairly low Alfenic Mach numbers, M{sub A} {approx}< 20, which is consistent with the theoretical conditions for the growth of whistler waves in the shock foot (M{sub A} {approx}< (m{sub i} /m{sub e}){sup 1/2}). Thus, if the whistler mechanism is the only robust electron injection process at work in SNR shocks, then SNRs that display non-thermal emission must have significantly amplified upstream magnetic fields. Such field amplification is likely achieved by the escaping cosmic rays, so electron and proton acceleration in SNR shocks must be interconnected.

  2. Study of radiative blast waves generated on the Z-beamlet laser.

    SciTech Connect

    Edens, Aaron D.; Schwarz, Jens

    2012-02-01

    This document describes the original goals of the project to study the Vishniac Overstability on blast waves produced using the Z-Beamlet laser facility as well as the actual results. The proposed work was to build on earlier work on the facility and result in the best characterized set of data for such phenomena in the laboratory. To accomplish the goals it was necessary to modify the existing probe laser at the facility so that it could take multiple images over the course of 1-2 microseconds. Troubles with modifying the probe laser are detailed as well as the work that went into said modifications. The probe laser modification ended up taking the entire length of the project and were the major accomplishment of the research.

  3. On the Amplification of Magnetic Field by a Supernova Blast Shock Wave in a Turbulent Medium

    NASA Astrophysics Data System (ADS)

    Guo, Fan; Li, Shengtai; Li, Hui; Giacalone, Joe; Jokipii, J. R.; Li, David

    2012-03-01

    We have performed extensive two-dimensional magnetohydrodynamic simulations to study the amplification of magnetic fields when a supernova blast wave propagates into a turbulent interstellar plasma. The blast wave is driven by injecting high pressure in the simulation domain. The interstellar magnetic field can be amplified by two different processes, occurring in different regions. One is facilitated by the fluid vorticity generated by the "rippled" shock front interacting with the background turbulence. The resulting turbulent flow keeps amplifying the magnetic field, consistent with earlier work. The other process is facilitated by the growth of the Rayleigh-Taylor instability at the contact discontinuity between the ejecta and the shocked medium. This can efficiently amplify the magnetic field and tends to produce the highest magnetic field. We investigate the dependence of the amplification on numerical parameters such as grid-cell size and on various physical parameters. We show that the magnetic field has a characteristic radial profile such that the downstream magnetic field gets progressively stronger away from the shock. This is because the downstream magnetic field needs a finite time to reach the efficient amplification, and will get further amplified in the Rayleigh-Taylor region. In our simulation, we do not observe a systematic strong magnetic field within a small distance to the shock. This indicates that if the magnetic-field amplification in supernova remnants indeed occurs near the shock front, other processes such as three-dimensional instabilities, plasma kinetics, and/or cosmic ray effect may need to be considered to explain the strong magnetic field in supernova remnants.

  4. Influence of the forward wave on the efficiency of generating microwave radiation in a relativistic backward wave tube

    Microsoft Academic Search

    S. D. Korovin; S. D. Polevin; A. M. Roitman; V. V. Rostov; L. D. Moreland; E. Schamiloglu

    1996-01-01

    An analysis is made of the influence of the forward wave on the operation of a relativistic uniform backward wave tube. The\\u000a conditions are determined under which it is necessary to take account of asynchronous waves in the processes of energy exchange\\u000a between the electromagnetic field and the electron beam. It is shown that the forward wave can strongly influence

  5. ccsd00001789, Dispersion relation of nite amplitude Alfv en wave in a relativistic electron-positron

    E-print Network

    in a relativistic electron-positron plasma T. Hada a , S. Matsukiyo a and V. Mu~noz a;b a Department of Earth System of a #12;nite amplitude, parallel, circularly polarized Alfv#19;en wave in a relativistic electron-positron=2 is the electron/positron plasma frequency), and an Alfv#19;en wave, with high frequency cuto#11; at the positron

  6. EMIC waves and associated relativistic electron precipitation on 25-26 January 2013

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Halford, A.; Huang, C. L.; Spence, H. E.; Reeves, G. D.; Millan, R. M.; Redmon, R. J.; Smith, C. W.; Torbert, R. B.; Kurth, W. S.; Kletzing, C.; Claudepierre, S. G.; Blake, J. B.; Fennell, J. F.; Baker, D. N.

    2014-12-01

    It has been well established that electromagnetic ion cyclotron (EMIC) waves can resonantly interact with relativistic (E > 1 MeV) electrons and result in pitch angle scattering of the electrons. Through this wave-particle resonant interaction, significant electron losses to the atmosphere over some drift orbits are expected. Nevertheless, the direct observation evidence of precipitating electrons by EMIC wave scattering is limited, because the resonant interactions between EMIC waves and relativistic electrons are not fully understood and simultaneously measuring the relativistic electrons at low altitudes and the EMIC waves in the magnetosphere is often difficult. Using measurements from the Van Allen Probes, BARREL, and NOAA/POES, we perform a data-analysis study of EMIC waves and associated relativistic electron precipitation (REP) observed on 25-26 January 2013. The Van Allen Probe-B detected significant EMIC wave activity at L=2.1-3.9 and MLT=21.0-23.4 from 2353 UT, 25 January 2013 to 0046 UT, 26 January 2013. Meanwhile, NOAA/POES and BARREL detected REP events. Particularly, BARREL-1T observed clear precipitation of relativistic electrons at L~4.1 and MLT~20.7 for 33 minutes from 2342 UT, 25 January 2013. The total radiation belt electron content, estimated from local relativistic electron measurements on the Van Allen Probes, also demonstrates internal losses of the electrons around the EMIC wave activity. To further confirm the conjunction of the EMIC waves and REP, we calculate the electron minimum resonant energy (Emin) and pitch angle diffusion coefficient (D??) of the EMIC wave packets by using nominal ion composition, derived total ion density from the frequencies of upper hybrid resonance, and measured ambient and wave magnetic field.

  7. Numerical simulation of laser-target interaction and blast wave formation

    NASA Astrophysics Data System (ADS)

    Giuliani, John L., Jr.; Mulbrandon, Margaret; Hyman, Ellis

    1989-07-01

    A numerical hydrodynamics chemistry model to simulate the laser-target interaction experiment at the Naval Research Laboratory's PHAROS [Laser Interaction and Related Plasma Phenomena (Plenum, New York, 1986), Vol. 7, p. 857] is presented. Both laser-target and debris-background interactions are modeled, solving mass continuity, total momentum, and separate ion and electron internal energy equations. The model is appropriate for background densities?1 Torr. To accurately treat both the early-time planar ablation and the later spherical expansion of the blast wave, as well as the rear-side shock front, an oblate spheroidal coordinate system was adopted. The aluminum target ablates into and interacts with an ambient nitrogen gas, filling the facility chamber. The simulation models the target continuously from the solid state to the state of a highly ionized nonequilibrium plasma, including all charge states of aluminum and all charge states of the nitrogen background. The laser beam has a wavelength of 1 ?, a ˜5 nsec full width at half-maximum (FWHM), an intensity at the target surface ˜1013 W/cm2, and total energy varying from 20-100 J. The model accurately reproduces the measured time-of-flight profile and the mass of ablated aluminum. Expansion of the blast wave in the model follows the ideal Sedov relation until radiation losses force a deviation due to a failure in the constant energy assumption. In the shock wave region the simulations show electron density of a few times 1018 cm-3, temperatures ranging from 10-20 eV, and dominant nitrogen species of N+3 and N+4, all in agreement with experimental measurement. A calculated profile of electron density both in the shock and in the cavity region agree closely with experiment and imply an average aluminum charge state of 11 times ionized in the cavity out to late times, as predicted by the simulation described in this paper. The simulation suggests, also, that observed rear-side structuring is a result of a deceleration Rayleigh-Taylor instability. The model is capable of providing detailed predictions, which are presented, as to profiles of charge states, densities, and temperatures as a function of time; these predictions are not yet tested by experimental measurement.

  8. Modulational instability of ion-acoustic waves in fully relativistic two-component plasma

    NASA Astrophysics Data System (ADS)

    Ghosh, B.; Banerjee, S.

    2015-06-01

    Nonlinear amplitude modulation of ion-acoustic waves (IAWs) in a fully relativistic unmagnetized two-fluid plasma has been theoretically studied by using complete set of fully relativistic dynamic equations. To describe the nonlinear evolution of the wave envelope a nonlinear Schrödinger (NLS) equation is derived by using standard multiple scale perturbation technique. Using this equation it is shown that the wave becomes modulationally unstable as the wavenumber exceeds certain critical value. This critical wavenumber is found to decrease with increase in relativistic effect. The instability growth rate has also been calculated numerically for different values of plasma drift velocity. The growth rate is shown to decrease with increase in the relativistic effect.

  9. Blast-wave analysis of strange particle $m_T$ spectra in Pb-Pb collisions at the SPS

    E-print Network

    G. E. Bruno

    2004-10-11

    The transverse mass spectra of high statistics, high purity samples of K0s, Lambda, Xi and Omega particles produced in Pb-Pb collisions at SPS energy have been studied in the framework of the blast-wave model. The dependence of the freeze-out parameters on particle species and event centrality is discussed. Results at 40 A GeV/c are presented here for the first time.

  10. Colliding Blast Waves Driven by the Interaction of a Short-Pulse Laser with a Gas of Atomic Clusters

    Microsoft Academic Search

    Roland A. Smith; James Lazarus; Matthias Hohenberger; Alastair S. Moore; Joseph S. Robinson; Edward T. Gumbrell; Mike Dunne

    Collisions between shocks are commonly found in many astrophysical objects, however robust numerical models or laboratory\\u000a analogues of these complex systems remain challenging to implement. We report on the development of scaled laboratory experiments\\u000a which employ new techniques for launching and diagnosing colliding shocks and high Mach number blast waves, scalable to a\\u000a limited subset of astrophysically-relevant regimes. Use of

  11. Colliding Blast Waves Driven by the Interaction of a Short-Pulse Laser with a Gas of Atomic Clusters

    Microsoft Academic Search

    Roland A. Smith; James Lazarus; Matthias Hohenberger; Alastair S. Moore; Joseph S. Robinson; Edward T. Gumbrell; Mike Dunne

    2007-01-01

    Collisions between shocks are commonly found in many astrophysical objects, however robust numerical models or laboratory\\u000a analogues of these complex systems remain challenging to implement. We report on the development of scaled laboratory experiments\\u000a which employ new techniques for launching and diagnosing colliding shocks and high Mach number blast waves, scalable to a\\u000a limited subset of astrophysically-relevant regimes. Use of

  12. Recent advances in the study of a long pulse relativistic backward wave oscillator

    Microsoft Academic Search

    F. Hegeler; E. Schamiloglu; S. D. Korovin; V.V. Rostov

    1999-01-01

    Laser interferometry was recently used to diagnose plasma formation and evolution in the slow wave structure (SWS) of a relativistic backward wave oscillator (BWO) during the course of microwave generation. The results indicated that plasma from the cutoff neck inlet contributed to the termination of the high power microwave pulse. In an effort to mitigate this pulse shortening effect, the

  13. Testing relativistic theories of gravity with spacecraft-Doppler gravity-wave detection

    NASA Technical Reports Server (NTRS)

    Hellings, R. W.

    1978-01-01

    The response of a spacecraft Doppler-tracking system to the passage of a weak plane gravity wave of the most general polarization is calculated. Results show that the simultaneous tracking of several spacecraft could provide an unambiguous determination of the gravity-wave polarization, a much needed result in the continuing experimental testing of relativistic theories of gravity.

  14. Three dimensional electrostatic solitary waves in a dense magnetoplasma with relativistically degenerate electrons

    SciTech Connect

    Ata-ur-Rahman,; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan) [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Masood, W. [National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan) [National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); COMSATS, Institute of Information Technology, Park Road, Chak Shahzad, Islamabad 44000 (Pakistan); Eliasson, B. [Physics Department, University of Strathclyde, Glasgow G4 0NG, Scotland (United Kingdom)] [Physics Department, University of Strathclyde, Glasgow G4 0NG, Scotland (United Kingdom)

    2013-09-15

    In this paper, small but finite amplitude electrostatic solitary waves in a relativistic degenerate magnetoplasma, consisting of relativistically degenerate electrons and non-degenerate cold ions, are investigated. The Zakharov-Kuznetsov equation is derived employing the reductive perturbation technique and its solitary wave solution is analyzed. It is shown that only compressive electrostatic solitary structures can propagate in such a degenerate plasma system. The effects of plasma number density, ion cyclotron frequency, and direction cosines on the profiles of ion acoustic solitary waves are investigated and discussed at length. The relevance of the present investigation vis-a-vis pulsating white dwarfs is also pointed out.

  15. The Construction of a 'Relativistic' Wave-Particle: The Soliton.

    ERIC Educational Resources Information Center

    Isenberg, Cyril

    1982-01-01

    Although most waves studied by students satisfy the linear equation, particle physicists have become interested in nonlinear waves--those not satisfying the superposition principle. A mechanical wave system, satisfying the sine-Gordon equation, can be constructed using a modified transverse wave system to demonstrate nonlinear wave-particle…

  16. ULF waves and relativistic electron acceleration and losses from the radiation belts: A superposed epoch analysis

    NASA Astrophysics Data System (ADS)

    Georgiou, Marina; Daglis, Ioannis; Zesta, Eftyhia; Katsavrias, Christos; Balasis, Georgios; Mann, Ian; Tsinganos, Kanaris

    2015-04-01

    Geospace magnetic storms are associated with either enhancements or decreases of the fluxes of electrons in the outer radiation belt. We examine the response of relativistic and ultra-relativistic electrons to 39 moderate and intense magnetic storms and compare these with concurrent observations of ULF wave power and of the plasmapause location. Following 27 of the magnetic storms, the ultra-relativistic electron population of the outer radiation belt was enhanced in the 2 - 6 MeV electron fluxes, as observed by SAMPEX. This enhancement was also seen in the electron phase space density derived from electron fluxes observed by the geosynchronous GOES satellites. On the other hand, the remaining 12 magnetic storms were not followed by enhancements in the relativistic electron population. We compare relativistic and ultra-relativistic electrons observations with the concurrent latitudinal and global distribution of wave power enhancements at Pc5 frequencies as detected by the CARISMA and IMAGE magnetometer arrays, as well as by magnetic stations collaborating in SuperMAG. During the main phase of both sets of magnetic storms, there is a marked penetration of Pc5 wave power to L shells as low as 2 -- especially during magnetic storms characterised by enhanced post-storm electron fluxes. Later in the recovery phase, Pc5 wave activity returns to more typical values and radial distribution with a peak at outer L shells. Pc5 wave activity was found to persist longer for the electron-enhanced storms than for those that do not produce such enhancements. We put our Pc5 wave observations in the context of the plasmapause location, as determined by IMAGE EUV observations. Specifically, we discuss the growth and decay characteristics of Pc5 waves in association with the plasmapause location, as a controlling factor for wave power penetration deep into the magnetosphere.

  17. Reflected blast wave resultants behind cantilever walls: A new prediction technique

    Microsoft Academic Search

    T. C. Chapman; T. A. Rose; P. D. Smith

    1995-01-01

    This paper presents the results of an experimental study conducted at approximately one-tenth scale to assess the sensitivity of blast parameters at a target structure located behind a protective blast wall to changes in charge size and geometrical configuration. A prediction technique, based on a modified scaled distance here termed “protection factor”, allows the assessment of peak reflected overpressure and

  18. Spectroscopic and interferometric measurements of laser-plasma produced blast waves

    NASA Astrophysics Data System (ADS)

    McLean, E. A.; Stamper, J. A.; Manka, C. K.; Griem, H. R.; Ali, A. W.; Ripin, B. H.

    1986-08-01

    A laser-produced plasma generates blast waves as it expands supersonically into a stationary photoionized background gas (N2) at a pressure of 1-5 Torr.1 Using a combination of spectroscopic and interferometric measurements, time- and space-resolved values of the temperature and density are obtained. This study was performed on targets in the NRL Pharos III laser facility with laser energies of 20-120 J and pulse durations of ˜5 ns. A 1-m spectrograph equipped with three photomultiplier channels, which are calibrated on an absolute scale, is used for the spectroscopic measurements. The interferometry is done with a folded-wavefront interferometer. It uses an optical probe pulse at 5270 Å that is split off of the main laser pulse, reduced in pulse duration (˜300 ps), and time delayed. Interferometric measurements can be made simultaneously with the spectroscopic measurements. Experimental data and the technique of analysis will be shown. This work was supported by the Defense Nuclear Agency.

  19. Laser driven high energy density radiative blast waves launched in clustered gases

    NASA Astrophysics Data System (ADS)

    Olsson-Robbie, Stefan; Doyle, Hugo; Lowe, Hazel; Price, Chris; Bigourd, Damien; Patankar, Siddharth; Mecseki, Katalin; Booth, Nicola; Scott, Robbie; Moore, Alastair; Hohenberger, Matthias; Rodriguez, Rafael; Gumbrell, Edward; Symes, Daniel; Smith, Roland

    2012-10-01

    Intense lasers deposit energy efficiently in clustered gases creating hot plasma with low density, conditions ideal for launching radiative blast waves (BWs) of interest for laboratory astrophysics (LA). We report measurements in a range of gases irradiated by the Astra-Gemini laser with energies >10J. Optical imaging, self emission and temporally resolved x-ray spectra are used to characterise BW evolution. The high repetition rate of the laser allows us to explore the influence of atomic number and density on the BW dynamics. Altering the emitted radiation and opacity of the medium has a strong effect on the BW profile and energy loss. Strongly radiative BWs exhibit shell thinning, increasing their susceptibility to instabilities. We have demonstrated the onset of a velocity instability, driven by the exchange of energy between the shock and precursor in krypton BWs. We discuss the threshold conditions for this behaviour and the potential to study spatial shock front instabilities. Our results will be compared to simulations and analytical calculations with a view to designing scalable LA experiments.

  20. Three distinct stages of the unsteady flow behind the shock wave formed by the normal reflection of a planar strong point blast wave from a wall

    Microsoft Academic Search

    Ting Aili

    1986-01-01

    The method of characteristics with shock fitting and a family of continuous C-characteristic lines are used for the analysis\\u000a of the normal reflection of a planar strong point blast wave from a wall. Several techniques are devised in order to increase\\u000a the accuracy of calculation for the problem including two complex singularities. New data for the flow field near the

  1. Six-Wave Forward Scattering of Short-Pulse Laser Light at Relativistic Intensities

    NASA Astrophysics Data System (ADS)

    Barr, H. C.; Berwick, S. J.; Mason, P.

    1998-10-01

    Forward scattering of short linearly polarized laser pulses in underdense plasma at relativistic intensities is examined. The linear polarization gives rise to a six-wave hybrid of the Raman forward scattering and relativistic modulational instabilities. Destructive interference between fluctuations in electron density and relativistic mass through the intervention of two high-frequency electrostatic modes decouples higher-order harmonics. This allows simple spacetime and spectral laser-pulse rest-frame models to be derived which are valid for arbitrarily high-laser intensities.

  2. Weakly relativistic quantum kinetic theory for electrostatic wave modes in magnetized plasmas

    SciTech Connect

    Hussain, Azhar [Department of Physics, GC University Lahore, 54000 Lahore (Pakistan)] [Department of Physics, GC University Lahore, 54000 Lahore (Pakistan); Stefan, Martin; Brodin, Gert [Department of Physics, Umeå University, SE-901 87 Umeå (Sweden)] [Department of Physics, Umeå University, SE-901 87 Umeå (Sweden)

    2014-03-15

    We have derived the electrostatic dispersion relation in a magnetized plasma using a recently developed quantum kinetic model based on the Dirac equation. The model contains weakly relativistic spin effects such as Thomas precession, the polarization currents associated with the spin and the spin-orbit coupling. It turns out that for strictly electrostatic perturbations the non-relativistic spin effects vanish, and the modification of the classical dispersion relation is solely associated with the relativistic terms. Several new wave modes appear due the electron spin effects, and an example for astrophysical plasmas are given.

  3. Multidimensional effects on relativistic electrons in an oblique shock wave

    Microsoft Academic Search

    Mieko Toida; Kenta Shikii

    2010-01-01

    Particle simulations have revealed [1] that prompt electron acceleration to ultrarelativistic energies can occur in a magnetosonic shock wave propagating obliquely to an external magnetic field with the propagation speed of the shock wave vsh close to c theta, where theta is the propagation angle of the shock wave. In such a wave, some electrons are reflected near the end

  4. Relativistic warm plasma theory of nonlinear laser-driven electron plasma waves

    SciTech Connect

    Schroeder, Carl B.; Esarey, Eric

    2010-06-30

    A relativistic, warm fluid model of a nonequilibrium, collisionless plasma is developed and applied to examine nonlinear Langmuir waves excited by relativistically-intense, short-pulse lasers. Closure of the covariant fluid theory is obtained via an asymptotic expansion assuming a non-relativistic plasma temperature. The momentum spread is calculated in the presence of an intense laser field and shown to be intrinsically anisotropic. Coupling between the transverse and longitudinal momentum variances is enabled by the laser field. A generalized dispersion relation is derived for langmuir waves in a thermal plasma in the presence of an intense laser field. Including thermal fluctuations in three velocity-space dimensions, the properties of the nonlinear electron plasma wave, such as the plasma temperature evolution and nonlinear wavelength, are examined, and the maximum amplitude of the nonlinear oscillation is derived. The presence of a relativistically intense laser pulse is shown to strongly influence the maximum plasma wave amplitude for non-relativistic phase velocities owing to the coupling between the longitudinal and transverse momentum variances.

  5. Skull Flexure from Blast Waves: A New Mechanism for Brain Injury with Implications for Helmet Design

    E-print Network

    Moss, William C; Blackman, Eric G

    2008-01-01

    Traumatic brain injury [TBI] has become the signature injury of current military conflicts. The debilitating effects of TBI on society are long-lasting and costly. Although the mechanisms by which impacts cause TBI have been well researched, the mechanisms by which blasts cause TBI are not understood. Various mechanisms, including impacts caused by the blast, have been investigated, but blast-induced deformation of the skull has been neglected. Through the use of hydrodynamical numerical simulations, we have discovered that non-lethal blasts can induce sufficient flexure of the skull to generate potentially damaging loads in the brain, even if no impact occurs. This mechanism has implications for the diagnosis of TBI in soldiers and the design of protective equipment such as helmets.

  6. Blast injury.

    PubMed

    de Candole, C A

    1967-01-28

    The shock wave generated by an explosion ("blast wave") may cause injury in any or all of the following: (1) direct impact on the tissues of variations in environmental pressure; (2) flying glass and other debris set in motion by it; (3) propulsion of the body. Injuries in the first category affect gas-containing organs (ears, lungs and intestines), and acute death is attributed to air forced into the coronary vessels via damaged pulmonary alveoli. It is estimated that overpressure sufficient to cause lung injury may occur up to five miles from a 20-megaton nuclear explosion. The greatest single hazard from blast is, however, flying glass, and serious wounding from this cause is possible up to 12 miles from an explosion of this magnitude. PMID:6015742

  7. Analysis of microscopic magnitudes of radiative blast waves launched in xenon clusters with collisional-radiative steady-state simulations

    NASA Astrophysics Data System (ADS)

    Rodriguez, R.; Espinosa, G.; Gil, J. M.; Florido, R.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Symes, D. R.; Hohenberger, M.; Smith, R. A.

    2013-08-01

    Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shocks such as radiative blast waves propagate. In this work, by means of collisional-radiative steady-state calculations, a characterization and an analysis of microscopic magnitudes of laboratory blast waves launched in xenon clusters are made. Thus, for example, the average ionization, the charge state distribution, the cooling time or photon mean free paths are studied. Furthermore, for a particular experiment, the effects of the self-absorption and self-emission in the specific intensity emitted by the shock front and that is going through the radiative precursor are investigated. Finally, for that experiment, since the electron temperature is not measured experimentally, an estimation of this magnitude is made both for the shock shell and the radiative precursor.

  8. Three-dimensional blast-wave-driven Rayleigh-Taylor instability and the effects of long-wavelength modes

    SciTech Connect

    Kuranz, C. C.; Drake, R. P.; Grosskopf, M. J.; Budde, A.; Krauland, C.; Marion, D. C.; Visco, A. J.; Ditmar, J. R. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Robey, H. F.; Remington, B. A.; Miles, A. R.; Cooper, A. B. R.; Sorce, C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Plewa, T. [Department of Scientific Computing, Florida State University, Tallahassee, Florida 32306 (United States); Hearn, N. C. [ASC Flash Center, University of Chicago, Chicago, Illinois 60637 (United States); Killebrew, K. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Knauer, J. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York (United States); Arnett, D. [Steward Observatory, University of Arizona, Tucson, Arizona 85721 (United States); Donajkowski, T. [Jet Propulsion Laboratory, Pasadena, California 91109 (United States)

    2009-05-15

    This paper describes experiments exploring the three-dimensional (3D) Rayleigh-Taylor instability at a blast-wave-driven interface. This experiment is well scaled to the He/H interface during the explosion phase of SN1987A. In the experiments, {approx}5 kJ of energy from the Omega laser was used to create a planar blast wave in a plastic disk, which is accelerated into a lower-density foam. These circumstances induce the Richtmyer-Meshkov instability and, after the shock passes the interface, the system quickly becomes dominated by the Rayleigh-Taylor instability. The plastic disk has an intentional pattern machined at the plastic/foam interface. This perturbation is 3D with a basic structure of two orthogonal sine waves with a wavelength of 71 {mu}m and an amplitude of 2.5 {mu}m. Additional long-wavelength modes with a wavelength of either 212 or 424 {mu}m are added onto the single-mode pattern. The addition of the long-wavelength modes was motivated by the results of previous experiments where material penetrated unexpectedly to the shock front, perhaps due to an unintended structure. The current experiments and simulations were performed to explore the effects of this unintended structure; however, we were unable to reproduce the previous results.

  9. Blast-wave model description of the Hanbury-Brown–Twiss radii in pp collisions at LHC energies

    NASA Astrophysics Data System (ADS)

    Bialas, Andrzej; Florkowski, Wojciech; Zalewski, Kacper

    2015-04-01

    The blast wave model is applied to the recent data on Hanbury-Brown–Twiss radii in pp collisions, measured by the ALICE Collaboration. A reasonable description of data is obtained for a rather low temperature of the kinetic freeze-out, T? 100 MeV, and the transverse profile corresponding to the emission from a shell of a fairly small width 2? ˜ 1.5 fm. The size and the life-time of the produced system are determined for various multiplicities of the produced particles.

  10. Breaking of relativistically intense longitudinal space charge waves: A description using Dawson sheet model

    NASA Astrophysics Data System (ADS)

    Sengupta, Sudip

    2014-02-01

    Spatio-temporal evolution of relativistically intense longitudinal space charge waves in a cold homogeneous plasma is studied analytically as well as numerically, as an initial value problem, using Dawson sheet model. It is found that, except for very special initial conditions which generates the well known longitudinal Akhiezer-Polovin mode, for all other initial conditions, the waves break through a novel mechanism called phase mixing at an amplitude well below the Akhiezer-Polovin limit. An immediate consequence of this is, that Akhiezer-Polovin waves break when subjected to arbitrarily small longitudinal perturbations. We demonstrate this by performing extensive numerical simulations. This result may be of direct relevance to ultrashort, ultraintense laser/beam pulse-plasma interaction experiments where relativistically intense waves are routinely excited.

  11. Breaking of relativistically intense longitudinal space charge waves: A description using Dawson sheet model

    SciTech Connect

    Sengupta, Sudip, E-mail: sudip@ipr.res.in [Institute for Plasma Research, Bhat , Gandhinagar - 382428 (India)

    2014-02-11

    Spatio-temporal evolution of relativistically intense longitudinal space charge waves in a cold homogeneous plasma is studied analytically as well as numerically, as an initial value problem, using Dawson sheet model. It is found that, except for very special initial conditions which generates the well known longitudinal Akhiezer-Polovin mode, for all other initial conditions, the waves break through a novel mechanism called phase mixing at an amplitude well below the Akhiezer-Polovin limit. An immediate consequence of this is, that Akhiezer-Polovin waves break when subjected to arbitrarily small longitudinal perturbations. We demonstrate this by performing extensive numerical simulations. This result may be of direct relevance to ultrashort, ultraintense laser/beam pulse-plasma interaction experiments where relativistically intense waves are routinely excited.

  12. Enhanced frequency agility of high-power relativistic backward wave oscillators

    Microsoft Academic Search

    L. D. Moreland; E. Schamiloglu; R. W. Lemke; A. M. Roitman; S. D. Korovin; V.V. Rostov

    1996-01-01

    This paper describes how finite length effects in high-power backward wave oscillators can be exploited in a controlled manner to achieve enhanced frequency agility. Experiments were performed using a Sinus-6 high-power relativistic repetitively pulsed electron beam accelerator. A uniform slow wave structure was used in these studies and its parameters were fixed. Sections of smooth-walled circular waveguide of varying lengths

  13. A multigigawatt X-Band relativistic backward wave oscillator with a modulating resonant reflector

    Microsoft Academic Search

    A. I. Klimov; I. K. Kurkan; S. D. Polevin; V. V. Rostov; E. M. Tot’meninov

    2008-01-01

    Effective generation regime with a high output pulse power has been experimentally realized in a relativistic backward wave\\u000a oscillator (RBWO) with a resonant reflector and a slow-wave system having a diameter 1.6 times the radiation wavelength. At\\u000a a guiding magnetic field of 4.5 T, the maximum peak power amounted to 4.3 GW at a frequency of 9.4 GHz, an efficiency

  14. Beat wave excitation of electron plasma wave by relativistic cross focusing of cosh-Gaussian laser beams in plasma

    NASA Astrophysics Data System (ADS)

    Singh, Arvinder; Gupta, Naveen

    2015-06-01

    A scheme for beat wave excitation of electron plasma wave (EPW) is proposed by relativistic cross-focusing of two coaxial Cosh-Gaussian (ChG) laser beams in an under dense plasma. The plasma wave is generated on account of beating of two coaxial laser beams of frequencies ?1 and ?2 . The mechanism for laser produced nonlinearity is assumed to be relativistic nonlinearity in electron mass. Following moment theory approach in Wentzel Kramers Brillouin (W.K.B) approximation, the coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived. The relativistic nonlinearity depends not only on the intensity of first laser beam but also on the intensity of second laser beam. Therefore, propagation dynamics of one laser beam affect that of second beam and hence cross-focusing of the two laser beams takes place. Due to non uniform intensity distribution of pump laser beams, the background electron concentration gets modified. The amplitude of EPW, which depends on the background electron concentration, thus gets nonlinearly coupled with the laser beams. The effects of relativistic electron mass nonlinearity and the cross-focusing of pump beams on excitation of EPW have been incorporated. Numerical simulations have been carried out to investigate the effect of laser as well as plasma parameters on cross-focusing of laser beams and further its effect on power of excited EPW.

  15. Multidimensional effects on relativistic electrons in an oblique shock wave

    NASA Astrophysics Data System (ADS)

    Toida, Mieko; Shikii, Kenta

    2010-11-01

    Particle simulations have revealed [1] that prompt electron acceleration to ultrarelativistic energies can occur in a magnetosonic shock wave propagating obliquely to an external magnetic field with the propagation speed of the shock wave vsh close to c ?, where ? is the propagation angle of the shock wave. In such a wave, some electrons are reflected near the end of the main pulse of the shock wave, get trapped and are energized in the main pulse region. Once electrons are trapped, they cannot readily escape from the wave because of the electromagnetic fields they themselves produce [2]. Although the extensive studies have examined electron trapping and acceleration by a shock wave, the theory and simulations were one-dimensional. In this study, we investigate multi-dimensional effects using two-dimensional (two spatial coordinates and three velocities), particle simulations. It is found that some electrons can be detrapped from the main pulse because of magnetic fluctuations propagating along the shock front. It is furthermore demonstrated that after detrapping, some electrons can be accelerated to much higher energies because they can enter and exit the shock wave several times as a result of their gyromotions. The generation of magnetic fluctuations due to whistler waves is also discussed. [0pt] [1] N. Bessho and Y. Ohsawa, Phys. Plasmas 6 3076 (1999).[0pt] [2] M. Toida and K. Shikii, Phys. Plasmas 16 112305 (2009).

  16. Generation of a d.c. field by nonlinear electromagnetic waves in relativistic plasmas

    Microsoft Academic Search

    G. S. Lakhina; B. Buti

    1981-01-01

    A finite amplitude linearly polarized electromagnetic wave propagating in a relativistic plasma, is found to generate the longitudinal d.c. as well as the oscillating electric field at the second harmonic. In a plasma consisting of only electrons and positrons, these fields cannot be generated.

  17. A possible method of reducing the magnetic field in a relativistic backward-wave tube

    Microsoft Academic Search

    I. K. Kurkan; V. V. Rostov; E. M. Tot’meninov

    1998-01-01

    A new configuration is proposed and implemented for a relativistic backward-wave tube using the symmetric TM01 mode which can appreciably enhance, by a factor of 2–3, the generation efficiency of high-power 3 cm radiation pulses using\\u000a low magnetic fields.

  18. Relativistic invariance of dispersion-relations and their associated wave-operators and Green-functions

    Microsoft Academic Search

    Dan Censor

    2008-01-01

    Identifying invariance properties helps in simplifying calculations and consolidating concepts. Presently the special relativistic invariance of dispersion relations and their associated scalar wave operators is investigated for general dispersive homogeneous linear media. Invariance properties of the four-dimensional Fourier transform integrals is demonstrated, from which the invariance of the scalar Green function is inferred. Dispersion relations and the associated group velocities

  19. Skull flexure from blast waves: a mechanism for brain injury with implications for helmet design

    SciTech Connect

    Moss, W C; King, M J; Blackman, E G

    2009-04-14

    Traumatic brain injury [TBI] has become a signature injury of current military conflicts. The debilitating effects of TBI are long-lasting and costly. Although the mechanisms by which impacts cause TBI have been well researched, the mechanisms by which blasts cause TBI are not understood. Various possibilities have been investigated, but blast-induced deformation of the skull has been neglected. From numerical hydrodynamic simulations, we have discovered that nonlethal blasts can induce sufficient flexure of the skull to generate potentially damaging loads in the brain, even if no impact occurs. The possibility that this mechanism may contribute to TBI has implications for the diagnosis of soldiers and the design of protective equipment such as helmets.

  20. Linear and nonlinear wave propagation in weakly relativistic quantum plasmas

    SciTech Connect

    Stefan, Martin; Brodin, Gert [Department of Physics, Umea University, SE-901 87 Umea (Sweden)

    2013-01-15

    We consider a recently derived kinetic model for weakly relativistic quantum plasmas. We find that that the effects of spin-orbit interaction and Thomas precession may alter the linear dispersion relation for a magnetized plasma in case of high plasma densities and/or strong magnetic fields. Furthermore, the ponderomotive force induced by an electromagnetic pulse is studied for an unmagnetized plasma. It turns out that for this case the spin-orbit interaction always gives a significant contribution to the quantum part of the ponderomotive force.

  1. Relativistic effects on cyclotron wave absorption by an energetic electron tail in the PLT tokamak

    SciTech Connect

    Mazzucato, E.; Efthimion, P.; Fidone, I.

    1984-07-01

    Electron cyclotron wave absorption by mildly relativistic electrons in the low density regime of the PLT tokamak is investigated. Appreciable wave damping is found for vertical propagation at frequencies of 50, 60, and 70 GHz when the spatially constant cyclotron frequency is 89 GHz. The perpendicular temperature T/sub perpendicular/(v/sub parallel/) of the fast tail is also measured from emission of radiation in the same direction. The results obtained are in satisfactory agreement with the theory of wave emission and absorption.

  2. Particle acceleration in ultra-relativistic parallel shock waves

    E-print Network

    A. Meli; J. J Quenby

    2002-12-13

    Monte-Carlo computations for highly relativistic parallel shock particle acceleration are presented for upstream flow gamma factors, $\\Gamma=(1-V_{1}^{2}/c^{2})^{-0.5}$ with values between 5 and $10^{3}$. The results show that the spectral shape at the shock depends on whether or not the particle scattering is small angle with $\\delta \\theta 2r_{g} \\Gamma^{2}$ where $\\lambda$ is the scattering mean free path along the field line and $r_{g}$ the gyroradius, these quantities being measured in the plasma flow frame. The large angle scattering case exhibits distinctive structure superimposed on the basic power-law spectrum, largely absent in the pitch angle case. Also, both cases yield an acceleration rate faster than estimated by the conventional, non-relativistic expression, $t_{acc}=[c/(V_{1}-V_{2})] [\\lambda_{1}/V_{1}+\\lambda_{2}/V_{2}]$ where '1' and '2' refer to upstream and downstream and $\\lambda$ is the mean free path. A $\\Gamma^{2}$ energy enhancement factor in the first shock crossing cycle and a significant energy multiplication in the subsequent shock cycles are also observed. The results may be important for our understanding of the production of very high energy cosmic rays and the high energy neutrino and gamma-ray output from Gamma Ray Bursts (GRB) and Active Galactic Nuclei (AGN).

  3. Relativistic electron precipitation events driven by electromagnetic ion-cyclotron waves

    NASA Astrophysics Data System (ADS)

    Khazanov, G.; Sibeck, D.; Tel'nikhin, A.; Kronberg, T.

    2014-08-01

    We adopt a canonical approach to describe the stochastic motion of relativistic belt electrons and their scattering into the loss cone by nonlinear EMIC waves. The estimated rate of scattering is sufficient to account for the rate and intensity of bursty electron precipitation. This interaction is shown to result in particle scattering into the loss cone, forming ˜10 s microbursts of precipitating electrons. These dynamics can account for the statistical correlations between processes of energization, pitch angle scattering, and relativistic electron precipitation events, that are manifested on large temporal scales of the order of the diffusion time ˜tens of minutes.

  4. Circularly polarized wave propagation in magnetofluid dynamics for relativistic electron-positron plasmas

    SciTech Connect

    Asenjo, Felipe A.; Munoz, Victor; Valdivia, Juan Alejandro [Departamento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Hada, Tohru [Department of Earth System Science and Technology, Kyushu University, Fukuoka 816-8580 (Japan)

    2009-12-15

    The dispersion relation for circularly polarized electromagnetic waves propagating in the direction of an external magnetic field in a relativistic electron-positron plasma with arbitrary constant drift velocities is obtained for constant temperature in the homentropic regime. This result is an exact solution of the nonlinear magnetofluid unification field formalism introduced by S. Mahajan [Phys. Rev. Lett. 90, 035001 (2003)], where the electromagnetic and fluid fields are coupled through the relativistic enthalpy density. The behavior of electromagnetic and Alfven branches of the dispersion relation are discussed for different temperatures.

  5. Compressional Mode ULF Waves Excitation and Relativistic Electron Acceleration during a Geomagnetic Storm Event

    NASA Astrophysics Data System (ADS)

    Shao, X.; Tan, L. C.; Tornquist, M.; Vassiliadis, D.; Sharma, A. S.; Fung, S. F.

    2012-12-01

    There has been increasing evidence indicating the importance of magnetospheric ULF waves in the Pc-5 frequency range in enhancing relativistic electron fluxes in the outer radiation belt. These ULF waves can be divided into two groups: poloidal modes and toroidal modes. In theory, electron acceleration by poloidal-mode wave should be more effective than by toroidal mode wave due to that electron drift motion is mainly along the azimuthal direction overlapping with compressional (poloidal) mode wave electric field. We found evidence of relativistic electron acceleration by the compressional-mode ULF waves during a storm sudden commencement event on September 25, 2001. In this event, the energetic electron flux measured by LANL shows modulations of low-energy electrons and acceleration of high-energy electrons by the compressional mode electric field oscillations over 2-3 hours. The energy threshold of accelerated electrons at the geosynchronous orbit agrees well with the theory of drift-resonant interaction of magnetospheric electrons with compressional-mode ULF waves. Global MHD simulation of the event through NASA/CCMC will also be presented.

  6. Compressional Mode ULF Waves Excitation and Relativistic Electron Acceleration during a Geomagnetic Storm Event

    NASA Astrophysics Data System (ADS)

    Shao, Xi; Tan, L. C.; Sharma, A. S.; Fung, S. F.; Tornquist, Mattias; Vassiliadis, Dimitris

    2012-10-01

    There has been increasing evidence indicating the importance of magnetospheric ULF waves in the Pc-5 frequency range in enhancing relativistic electron fluxes in the outer radiation belt. These ULF waves can be divided into two groups: poloidal modes and toroidal modes. In theory, electron acceleration by poloidal-mode wave should be more effective than by toroidal mode wave due to that electron drift motion is mainly along the azimuthal direction overlapping with compressional (poloidal) mode wave electric field. We found evidence of relativistic electron acceleration by the compressional-mode ULF waves during a storm sudden commencement event on September 25, 2001. In this event, the energetic electron flux measured by LANL shows modulations of low-energy electrons and acceleration of high-energy electrons by the compressional mode electric field oscillations over 2-3 hours. The energy threshold of accelerated electrons at the geosynchronous orbit agrees well with the theory of drift-resonant interaction of magnetospheric electrons with compressional-mode ULF waves. Global MHD simulation of the event through NASA/CCMC will also be presented.

  7. Propagation of solitary waves in relativistic electron-positron-ion plasmas with kappa distributed electrons and positrons

    SciTech Connect

    Shah, Asif; Mahmood, S.; Haque, Q. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)

    2011-11-15

    Electrostatic ion acoustic solitary waves are studied in a plasma system comprising of relativistic ions, kappa distributed electrons, and positrons. The increase in the relativistic streaming factor and positron and electron kappa parameters cause the soliton amplitude to thrive. However, the soliton amplitude diminishes as the positron concentration is increased in the system. Our results are general and may be helpful, in understanding nonlinear phenomena in the presence of kappa distibuted electrons, positrons, and relativistically streaming ions.

  8. Wave function of particle and the coordinates distribution in relativistic quantum theory

    E-print Network

    V. F. Krotov

    2008-07-03

    The conditions for observation of the particle coordinates, required by logic of the Special Relativity and filtering the quantum field effects, are described. A general relation between the corresponding density of probability and the wave function is found. It is a relativistic invariant describing probability of the particle emergences in space -time. This density is concretized for bosons, both scalar and vector (including photon), charged and neutral, also electron. The Heisenberg's uncertainty relations have been approved in regards to relativistic particle. As applied to the quantum field, this new construction is transformed to new characteristic of the particles distribution in space-time, which complete distribution throughout impulses. The operators of these distributions and the invariant relativistic description for free quantum fields have been obtained. These new properties of the particles and fields are proposed for experimental investigations.

  9. Universitat Regensburg Points of general relativistic shock wave

    E-print Network

    Regensburg, Universität - Naturwissenschaftliche Fakultät I

    . 28/2011 #12;arXiv:1105.0798v1[gr-qc]4May2011 POINTS OF GENERAL RELATIVISITIC SHOCK WAVE INTERACTION, that can form from the evolution of smooth initial data, but at which the spacetime is not locally inertial at every The ideas and methods presented here are the creation of Moritz Reintjes. The detailed

  10. In search of a new ULF wave index: Comparison of Pc5 power with dynamics of geostationary relativistic electrons

    Microsoft Academic Search

    O. Kozyreva; V. Pilipenko; M. J. Engebretson; K. Yumoto; J. Watermann; N. Romanova

    2007-01-01

    A new ULF wave index, characterizing the turbulent level of the geomagnetic field, has been calculated and applied to the analysis of relativistic electron enhancements during space weather events in March–May 1994 and September 1999. This global wave index has been produced from the INTERMAGNET, MACCS, CPMN, and Greenland dense magnetometer arrays in the northern hemisphere. A similar ULF wave

  11. Exact relativistic expressions for wave refraction in a generally moving fluid.

    PubMed

    Cavalleri, G; Tonni, E; Barbero, F

    2013-04-01

    The law for the refraction of a wave when the two fluids and the interface are moving with relativistic velocities is given in an exact form, at the same time correcting a first order error in a previous paper [Cavalleri and Tonni, Phys. Rev. E 57, 3478 (1998)]. The treatment is then extended to a generally moving fluid with variable refractive index, ready to be applied to the refraction of acoustic, electromagnetic, or magnetohydrodynamic waves in the atmosphere of rapidly rotating stars. In the particular case of a gas cloud receding because of the universe expansion, our result can be applied to predict observable micro- and mesolensings. The first order approximation of our exact result for the deviation due to refraction of the light coming from a further quasar has a relativistic dependence equal to the one obtained by Einsteins' linearized theory of gravitation. PMID:23679540

  12. Progress in high power, high efficiency relativistic traveling wave tube amplifiers

    SciTech Connect

    Nation, J.A.; Naqvi, S.A.; Kerslick, G.S. [Laboratory of Plasma Studies School of Electrical Engineering, Cornell University, Ithaca, New York 14853 (United States); Schaechter, L. [Laboratory of Plasma Studies School of Electrical Engineering Cornell University, Ithaca, New York 14853 (United States of America)]|[Department of Electrical Engineering, Technion-Israel Institute of Technology, Haifa32000 (Israel)

    1997-03-01

    We present an overview of recent research at Cornell University on the use of relativistic traveling wave tube amplifiers for high power microwave generation. We consider three topics namely the dependence of the amplifier gain on the beam energy, axial energy extraction using a TM to TEM mode converter, and techniques for enhancing the efficiency of the amplifier to at least 50{percent}. {copyright} {ital 1997 American Institute of Physics.}

  13. The role of electromagnetic instabilities in the precursor of collisionless relativistic shock waves

    Microsoft Academic Search

    Martin Lemoine; Guy Pelletier

    2011-01-01

    Fermi acceleration can develop efficiently at relativistic collisionless\\u000ashock waves provided the upstream (unshocked) plasma is weakly magnetized. At\\u000alow magnetization, the large size of the shock precursor indeed provides enough\\u000atime for electromagnetic micro-instabilities to grow and such\\u000amicro-instabilities generate small scale turbulence that in turn provides the\\u000ascattering required. The present paper extends our previous analysis on the

  14. Coherent kilo-electron-volt backscattering from plasma-wave boosted relativistic electron mirrors

    SciTech Connect

    Li, F. Y.; Chen, M., E-mail: minchen@sjtu.edu.cn; Liu, Y.; Zhang, J. [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Sheng, Z. M., E-mail: zhengming.sheng@strath.ac.uk, E-mail: zmsheng@sjtu.edu.cn [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Wu, H. C. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Meyer-ter-Vehn, J. [Max-Planck-Institut für Quantenoptik, D-85748 Garching (Germany); Mori, W. B. [University of California, Los Angeles, California 90095-1547 (United States)

    2014-10-20

    A different parameter regime of laser wakefield acceleration driven by sub-petawatt femtosecond lasers is proposed, which enables the generation of relativistic electron mirrors further accelerated by the plasma wave. Integrated particle-in-cell simulation, including both the mirror formation and Thomson scattering, demonstrates that efficient coherent backscattering up to keV photon energy can be obtained with moderate driving laser intensities and high density gas targets.

  15. Powerful millimeter-wave generators based on the stimulated Cerenkov radiation of relativistic electron beams

    Microsoft Academic Search

    V. L. Bratman; G. G. Denisov; B. D. Kol'chugin; S. D. Korovin; G. D. Polevin; V. V. Rostov

    1984-01-01

    Effective relativistic Cerenkoy generators of various types were studied experimentally: orotrons, surface wave oscillators, and Smith-Purcell free-electron masers that were first realized. Single-mode generation was obtained in multimode systems using electrodynamic and electron methods of mode selection. The power obtained in this regime was 100 MW at 8.6 mm with the efficiency 10%, 50 MW at 5.5 mm with the

  16. High-efficiency subnanosecond microwave pulse generation in a relativistic backward wave tube

    Microsoft Academic Search

    S. D. Korovin; G. A. Mesyats; V. V. Rostov; M. R. Ul’maskulov; K. A. Sharypov; V. G. Shpak; S. A. Shunailov; M. I. Yalandin

    2002-01-01

    The regime of nonstationary oscillations with a short-time power burst, which is typical of the initial stage of a transient\\u000a process developed when a beam current significantly exceeds the starting level, is studied in a relativistic backward wave\\u000a tube (BWT) operating in the millimeter wavelength range. The results of numerical calculations allowed conditions to be established\\u000a that provide for a

  17. A periodic pulsed relativistic backward wave oscillator mechanically tunable in an expanded frequency band

    Microsoft Academic Search

    A. I. Klimov; I. K. Kurkan; S. D. Polevin; V. V. Rostov; E. M. Tot’meninov

    2007-01-01

    We have studied a periodic pulse train regime (1 s, 50 Hz) of a relativistic backward wave oscillator with a resonant reflector,\\u000a which can be mechanically tuned from pulse to pulse within a frequency band of 9% on a level of ?3 dB of the maximum in the\\u000a entire microwave peak power range in a magnetic field of 0.36 T.

  18. Dual-band relativistic backward wave oscillators based on a single beam and dual beams

    Microsoft Academic Search

    Wang Ting; Zhang Jian-de; Qian Bao-Liang; Zhang Xiao-Ping

    2010-01-01

    Two types of relativistic backward wave oscillators (RBWOs) used to produce dual-band microwaves are proposed and investigated by use of the particle-in-cell (PIC) simulation code KARAT [V. P. Tarakanov, User's Manual for Code Karat (Berkeley Research Associates, Springfield, VA, 1992)]. The first type of RBWO, for generation of C-band and X-band microwaves, is designed based on a single beam and

  19. Electron wave-packet dynamics in a relativistic electromagnetic field: 3-D analytical approximation

    Microsoft Academic Search

    J. Peatross; C. Müller; C. H. Keitel

    2007-01-01

    A solution to the Klein Gordon equation for a laser-driven electron is constructed from a superposition of Volkov states. The time-and space-dependent three-dimensional superposition integral can be evaluated analytically for an initial Gaussian momentum distribution when the expression for relativistic energy is expanded in a Taylor series over the scaled initial momenta. The solution preserves many complicated wave-packet dynamics in

  20. The role of stress waves in thoracic visceral injury from blast loading: modification of stress transmission by foams and high-density materials.

    PubMed

    Cooper, G J; Townend, D J; Cater, S R; Pearce, B P

    1991-01-01

    Materials have been applied to the thoracic wall of anaesthetised experimental animals exposed to blast overpressure to investigate the coupling of direct stress waves into the thorax and the relative contribution of compressive stress waves and gross thoracic compression to lung injury. The ultimate purpose of the work is to develop effective personal protection from the primary effects of blast overpressure--efficient protection can only be achieved if the injury mechanism is identified and characterized. Foam materials acted as acoustic couplers and resulted in a significant augmentation of the visceral injury; decoupling and elimination of injury were achieved by application of a high acoustic impedance layer on top of the foam. In vitro experiments studying stress wave transmission from air through various layers into an anechoic water chamber showed a significant increase in power transmitted by the foams, principally at high frequencies. Material such as copper or resin bonded Kevlar incorporated as a facing upon the foam achieved substantial decoupling at high frequencies--low frequency transmission was largely unaffected. An acoustic transmission model replicated the coupling of the blast waves into the anechoic water chamber. The studies suggest that direct transmission of stress waves plays a dominant role in lung parenchymal injury from blast loading and that gross thoracic compression is not the primary injury mechanism. Acoustic decoupling principles may therefore be employed to reduce the direct stress coupled into the body and thus reduce the severity of lung injury--the most simple decoupler is a high acoustic impedance material as a facing upon a foam, but decoupling layers may be optimized using acoustic transmission models. Conventional impacts producing high body wall velocities will also lead to stress wave generation and transmission--stress wave effects may dominate the visceral response to the impact with direct compression and shear contributing little to the aetiology of the injury. PMID:2050704

  1. Relativistic two-boson system in presence of electromagnetic plane waves

    E-print Network

    Droz-Vincent, Philippe

    2015-01-01

    The relativistic two-body problem is considered for spinless particles subject to an external macroscopic electromagnetic field. When this field is made of the monochromatic superposition of two conter-propagating plane waves (and provided the mutual interaction between particles is known), it is possible to write down explicitly a pair of coupled wave equations (corresponding to a pair of mass-shell constraints) which takes into account also the field contribution. These equations are manifestly covariant; constants of the motion are exhibited, so one ends up with a reduced problem concerning five degrees of freedom.

  2. Ku-band radiation produced by a relativistic backward wave oscillator

    SciTech Connect

    Leifeste, G.T.; Earley, L.M.; Swegle, J.A.; Poukey, J.W.; Miller, R.B.; Crist, C.E.; Wharton, C.B.; Ballard, W.P.

    1986-02-15

    Reported in this paper are the results of an experiment to produce high-power Ku-band (12--18 GHz) microwave radiation from a backward wave oscillator (BWO) driven by a relativistic electron beam. Experimentally measured output power was about 250 MW at 12.5 GHz and 100 MW at 14 GHz. A description of the slow wave structure is given along with theoretical predictions of the vacuum waveguide dispersion relations. The diagnostics to determine the frequency and power of the device are described. Finally, comparisons between the experimentally measured frequency and power, and the analytic and numerical simulations of the BWO are made.

  3. Detection of Gravitational Wave - An Application of Relativistic Quantum Information Theory

    E-print Network

    Ye Yeo; Chee Leong Ching; Jeremy Chong; Wee Kang Chua; Andreas Dewanto; Zhi Han Lim

    2006-05-16

    We show that a passing gravitational wave may influence the spin entropy and spin negativity of a system of $N$ massive spin-1/2 particles, in a way that is characteristic of the radiation. We establish the specific conditions under which this effect may be nonzero. The change in spin entropy and negativity, however, is extremely small. Here, we propose and show that this effect may be amplified through entanglement swapping. Relativistic quantum information theory may have a contribution towards the detection of gravitational wave.

  4. Spatiotemporal dispersion and wave envelopes with relativistic and pseudorelativistic characteristics.

    PubMed

    Christian, J M; McDonald, G S; Hodgkinson, T F; Chamorro-Posada, P

    2012-01-20

    A generic nonparaxial model for pulse envelopes is presented. Classic Schrödinger-type descriptions of wave propagation have their origins in slowly-varying envelopes combined with a Galilean boost to the local time frame. By abandoning these two simplifications, a picture of pulse evolution emerges in which frame-of-reference considerations and space-time transformations take center stage. A wide range of effects, analogous to those in special relativity, then follows for both linear and nonlinear systems. Explicit demonstration is presented through exact bright and dark soliton pulse solutions. PMID:22400744

  5. Blast-wave diagnosis of self-focusing of an intense laser pulse in a cluster medium

    SciTech Connect

    Symes, Daniel R.; Moore, Alastair S.; Comley, Andrew J.; Lazarus, James; Hohenberger, Matthias; Tisch, John W. G.; Smith, Roland A. [Blackett Laboratory, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BZ (United Kingdom)

    2007-06-15

    Self-focusing of intense laser pulses in a gas of atomic clusters is diagnosed in both long (>700 fs) and short (<100 fs) pulse regimes. This investigation uses blast-wave analysis techniques, which are sensitive to deposited energy, as a tool to identify locations of self-focusing. The detection of highly energetic x rays from the interaction of the short pulse with the clusters suggests the activation of electron acceleration in the self-focused high-intensity channels produced. The self-focusing is attributed to the optical properties of the clusters since it occurs at moderate laser powers and the cluster parameters are critical to the extent of the channel that forms.

  6. Blast-wave diagnosis of self-focusing of an intense laser pulse in a cluster medium

    NASA Astrophysics Data System (ADS)

    Symes, Daniel R.; Moore, Alastair S.; Comley, Andrew J.; Lazarus, James; Hohenberger, Matthias; Tisch, John W. G.; Smith, Roland A.

    2007-06-01

    Self-focusing of intense laser pulses in a gas of atomic clusters is diagnosed in both long (>700fs) and short (<100fs) pulse regimes. This investigation uses blast-wave analysis techniques, which are sensitive to deposited energy, as a tool to identify locations of self-focusing. The detection of highly energetic x rays from the interaction of the short pulse with the clusters suggests the activation of electron acceleration in the self-focused high-intensity channels produced. The self-focusing is attributed to the optical properties of the clusters since it occurs at moderate laser powers and the cluster parameters are critical to the extent of the channel that forms.

  7. Experimental study on Smith-Purcell radiations of weakly relativistic oversized backward wave oscillators

    NASA Astrophysics Data System (ADS)

    Iwasaki, Takayuki; Ogura, Kazuo; Magori, Shota; Kojima, Junpei; Yambe, Kiyoyuki

    2014-10-01

    Smith-Purcell (SP) radiations of weakly relativistic oversized backward wave oscillator (BWO) are examined experimentally. A bunching section composed of a coaxial slow wave structure with inner K-band corrugation is placed upstream from the oversized BWO. An annular beam less than 100 kV is self-bunched in the bunching section and then excites the oversized BWO. SP radiations are examined by using 25.5- and 45.0-GHz oversized BWOs. The beam is too far away from the walls of the oversized BWO for SP radiation to occur without the self-bunching. When the corrugation parameters of the bunching section are the same as those of the oversized BWO, enhanced SP radiations in the frequency region above the surface wave are observed even when the beam propagates outside the interaction region of the surface wave.

  8. Rapid startup in relativistic backward wave oscillator by injecting external backward signal

    SciTech Connect

    Song, W.; Teng, Y.; Zhang, Z. Q.; Li, J. W.; Sun, J.; Chen, C. H.; Zhang, L. J. [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an, Shanxi 710024 (China)

    2012-08-15

    Investigation on accelerating the building up of oscillation and achieving a rapid startup in powerful relativistic backward wave oscillator by injecting a weak external backward signal is carried out in this paper. Synchronizing the signal with the backward wave excited by intense electron beam extracting with slow wave structure, the initial noise is greatly reduced and mode competition is restrained. The analysis is demonstrated by high power X-band backward wave oscillator experiment, in which a plasma switch is designed to realize the backward signal injection. The results show that the significant reduction of microwave output delay is attained and the start time of oscillation is ahead of 10 ns with the energy conversion efficiency increases about 62%.

  9. Enhanced frequency agility of high-power relativistic backward wave oscillators

    SciTech Connect

    Moreland, L.D.; Schamiloglu, E. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Electrical and Computer Engineering] [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Electrical and Computer Engineering; Lemke, R.W. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States); Roitman, A.M.; Korovin, S.D.; Rostov, V.V. [Russian Academy of Sciences, Tomsk (Russian Federation). High Current Electronics Inst.] [Russian Academy of Sciences, Tomsk (Russian Federation). High Current Electronics Inst.

    1996-06-01

    This paper describes how finite length effects in high-power backward wave oscillators can be exploited in a controlled manner to achieve enhanced frequency agility. Experiments were performed using a Sinus-6 high-power relativistic repetitively pulsed electron beam accelerator. A uniform slow wave structure was used in these studies and its parameters were fixed. Sections of smooth-walled circular waveguide of varying lengths were inserted both before and after the slow wave structure. Variations in the length of smooth-walled waveguide on the order of a quarter-wavelength of the generated electromagnetic radiation were found to significantly affect both microwave frequency and radiation efficiency in a periodic-like manner. The experimental results were reproduced in TWOQUICK electromagnetic particle-in-cell simulations. A bandwidth of about 500 MHz centered around 9.5 GHz at hundreds of MW power levels has been achieved with constant beam and slow wave structure parameters.

  10. Reflection and absorption of electromagnetic waves obliquely incident on a half-space relativistic plasma

    SciTech Connect

    Imre, K.; Ozizmir, E.

    1980-08-01

    Reflection and absorption characteristics of electromagnetic waves obliquely incident upon a half-space relativistic Vlasov plasma are investigated. Numerical results comparing the properties of the s- and p-polarized waves are given. It is shown that the response of plasma can be best understood by studying the locations of the roots kappa/sub t/ and kappa/sub l/ of the transversal and longitudinal dispersion functions in the complex wavenumber plane. In general, s-polarized waves are reflected and p-polarized waves are absorbed more efficiently by the plasma. Total reflection occurs when kappa/sub t/ becomes zero for the case of s-polarization and when kappa/sub l/ becomes zero for the case of p-polarization. Total penetration of p-waves is obtained for sufficiently large frequencies at the Brewster angle theta/sub B/. These waves exhibit a sharp absorption peak at the characteristic angle theta/sub c/ at which the transversal transmission terminates. For a given temperature, p-waves are totally absorbed in the plasma at a specific frequency at which theta/sub B/=theta/sub c/. Absorption peaks are broader at higher temperatures. If both transversal and longitudinal modes propagate undamped at some value of angle of incidence theta, there exists a secondary smooth and broad absorption peak at larger values of theta for the p-waves. The magnitude of the secondary peak can also be appreciable at the ultrarelativistic temperatures.

  11. Derivation of the lattice Boltzmann model for relativistic hydrodynamics

    SciTech Connect

    Mendoza, M.; Herrmann, H. J. [Computational Physics for Engineering Materials, Institute for Building Materials, ETH Zuerich, Schafmattstrasse 6, HIF, CH-8093 Zuerich (Switzerland); Boghosian, B. M. [Department of Mathematics, Tufts University, Bromfield-Pearson, Medford, Massachusetts 02155 (United States); Succi, S. [Istituto per le Applicazioni del Calcolo C.N.R., Via dei Taurini, 19 00185, Rome, Italy, and Freiburg Institute for Advanced Studies, Albertstrasse, 19, D-79104, Freiburg (Germany)

    2010-11-15

    A detailed derivation of the lattice Boltzmann scheme for relativistic fluids recently proposed in M. Mendoza, B. Boghosian, H. Herrmann, and S. Succi, Phys. Rev. Lett. 105, 014502 (2010) is presented. The method is numerically validated and applied to the case of two quite different relativistic fluid-dynamic problems, namely, shock-wave propagation in quark-gluon plasmas and the impact of a supernova blast wave on massive interstellar clouds. Close to second-order convergence with the grid resolution, as well as linear dependence of computational time on the number of grid points and time steps, are reported.

  12. Stimulated scattering of waves in microwave generators with high-current relativistic electron beams: simulation of two-stage free-electron lasers

    Microsoft Academic Search

    V. L. BRATMAN; G. G. DENISOV; N. S. GINZBURG; A. V. SMORGONSKY; S. D. KOROVIN; S. D. POLEVIN; V. V. ROSTOV; M. I. YALANDIN

    1985-01-01

    A theory of stimulated scattering of electromagnetic waves by high-current relativistic electron beams is developed, with the transverse inhomogeneity of incident and scattered waves, the presence of a magnetic field focusing the particles and a space-charge field taken into account. The characteristic features of stimulated scattering that occurs directly in the interaction space of a powerful relativistic pump wave oscillator

  13. An optimization method of relativistic backward wave oscillator using particle simulation and genetic algorithms

    SciTech Connect

    Chen, Zaigao; Wang, Jianguo [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China) [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China); Northwest Institute of Nuclear Technology, P.O. Box 69-12, Xi'an, Shaanxi 710024 (China); Wang, Yue; Qiao, Hailiang; Zhang, Dianhui [Northwest Institute of Nuclear Technology, P.O. Box 69-12, Xi'an, Shaanxi 710024 (China)] [Northwest Institute of Nuclear Technology, P.O. Box 69-12, Xi'an, Shaanxi 710024 (China); Guo, Weijie [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)] [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an, Shaanxi 710049 (China)

    2013-11-15

    Optimal design method of high-power microwave source using particle simulation and parallel genetic algorithms is presented in this paper. The output power, simulated by the fully electromagnetic particle simulation code UNIPIC, of the high-power microwave device is given as the fitness function, and the float-encoding genetic algorithms are used to optimize the high-power microwave devices. Using this method, we encode the heights of non-uniform slow wave structure in the relativistic backward wave oscillators (RBWO), and optimize the parameters on massively parallel processors. Simulation results demonstrate that we can obtain the optimal parameters of non-uniform slow wave structure in the RBWO, and the output microwave power enhances 52.6% after the device is optimized.

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

    SciTech Connect

    Ata-ur-Rahman,; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan); National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, QAU Campus, Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    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.

  15. Exact solution of the relativistic magnetohydrodynamic equations in the background of a plane gravitational wave with combined polarization

    E-print Network

    A. A. Agathonov; Yu. G. Ignatyev

    2011-01-09

    We obtain an exact solution of the self-consistent relativistic magnetohydrodynamic equations for an anisotropic magnetoactive plasma in the background of a plane gravitational wave metric (PGW) with an arbitrary polarization. It is shown that, in the linear approximation in the gravitational wave amplitude, only the $\\mathbf{e_+}$ polarization of the PGW interacts with a magnetoactive plasma.

  16. Cylindrical and Spherical Ion-Acoustic Shock Waves in a Relativistic Degenerate Multi-Ion Plasma

    NASA Astrophysics Data System (ADS)

    Hossen, M. R.; Nahar, L.; Mamun, A. A.

    2014-12-01

    A rigorous theoretical investigation has been made to study the existence and basic features of the ion-acoustic (IA) shock structures in an unmagnetized, collisionless multi-ion plasma system (containing degenerate electron fluids, inertial positively as well as negatively charged ions, and arbitrarily charged static heavy ions). This investigation is valid for both non-relativistic and ultra-relativistic limits. The reductive perturbation technique has been employed to derive the modified Burgers equation. The solution of this equation has been numerically examined to study the basic properties of shock structures. The basic features (speed, amplitude, width, etc.) of these electrostatic shock structures have been briefly discussed. The basic properties of the IA shock waves are found to be significantly modified by the effects of arbitrarily charged static heavy ions and the plasma particle number densities. The implications of our results in space and interstellar compact objects like white dwarfs, neutron stars, black holes, and so on have been briefly discussed.

  17. Relativistic modulational instability of electron-acoustic waves in an electron-pair ion plasma

    SciTech Connect

    Misra, A. P. [Department of Mathematics, Siksha Bhavana, Visva-Bharati University, Santiniketan-731 235 (India); Shukla, P. K. [Institut fuer Theoretische Physik IV and Centre for Plasma Science and Astrophysics, Fakultaet fuer Physik and Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum, Germany and School of Physics, University of KwaZulu-Natal, 4000 Durban (South Africa)

    2008-12-15

    The modulational instability of finite amplitude electron-acoustic waves (EAWs) along the external magnetic field is studied in an electron-pair ion plasma. Accounting for the relativistic electron mass variation nonlinearity and the Boltzmann distribution of both positive and negative ions, new regimes for the relativistic modulational instability (MI) for the low frequency (below the electron gyrofrequency) short-wavelength (in comparison with the ion gyroradius) modes are obtained numerically. It is found that the presence of a significant fraction of negative ions suppresses the MI growth/decay rate for the modulated EAW packets. The results could be of important for understanding the origin of amplitude modulated EAW packets in space (e.g., Earth's magnetotail) as well as in laboratory plasmas.

  18. Effect of Oblique Electromagnetic Ion Cyclotron Waves on Relativistic Electron Scattering: CRRES Based Calculation

    NASA Technical Reports Server (NTRS)

    Gamayunov, K. V.; Khazanov, G. V.

    2007-01-01

    We consider the effect of oblique EMIC waves on relativistic electron scattering in the outer radiation belt using simultaneous observations of plasma and wave parameters from CRRES. The main findings can be s ummarized as follows: 1. In 1comparison with field-aligned waves, int ermediate and highly oblique distributions decrease the range of pitc h-angles subject to diffusion, and reduce the local scattering rate b y an order of magnitude at pitch-angles where the principle absolute value of n = 1 resonances operate. Oblique waves allow the absolute va lue of n > 1 resonances to operate, extending the range of local pitc h-angle diffusion down to the loss cone, and increasing the diffusion at lower pitch angles by orders of magnitude; 2. The local diffusion coefficients derived from CRRES data are qualitatively similar to the local results obtained for prescribed plasma/wave parameters. Conseq uently, it is likely that the bounce-averaged diffusion coefficients, if estimated from concurrent data, will exhibit the dependencies similar to those we found for model calculations; 3. In comparison with f ield-aligned waves, intermediate and highly oblique waves decrease th e bounce-averaged scattering rate near the edge of the equatorial lo ss cone by orders of magnitude if the electron energy does not excee d a threshold (approximately equal to 2 - 5 MeV) depending on specified plasma and/or wave parameters; 4. For greater electron energies_ ob lique waves operating the absolute value of n > 1 resonances are more effective and provide the same bounce_averaged diffusion rate near the loss cone as fiel_aligned waves do.

  19. Long-term cyclotron dynamics of relativistic wave packets: Spontaneous collapse and revival

    NASA Astrophysics Data System (ADS)

    Demikhovskii, V. Ya.; Maksimova, G. M.; Perov, A. A.; Telezhnikov, A. V.

    2012-02-01

    In this work we study the effects of collapse and revival, as well as the zitterbewegung (ZB) phenomenon, for the relativistic electron wave packets, which are a superposition of the states with quantum numbers sharply peaked around some Landau level n0 of the order of few tens. The probability densities as well as average velocities of the packet center and the average spin components were calculated analytically and their evolution is visualized. Our computations demonstrate that due to the dephasing of the states for times larger than the cyclotron period the initial wave packet (which includes the states with the positive energy only) loses the spatial localization so that the evolution can no longer be described classically. However, at the half-revival time t=TR/2 its reshaping takes place first. It is shown that the behavior of the wave packet containing the states of both energy bands (with En>0 and En<0) is more complicated. At short times of a few classical periods such a packet splits into two parts, which rotate with cyclotron frequency in the opposite directions and meet each other every one-half of the cyclotron period. At these moments their wave functions have a significant overlap that leads to ZB, and at the time of fractional revival each of two subpackets is decomposed into few packet fractions. However, at t=TR each of the two subpackets (with positive or negative energy) restores at various points of the cyclotron orbit, which makes reshaping of the initial wave packet impossible, entirely unlike the wave packet which consists of states with energies En>0 only. The obtained results can be useful for the description of electromagnetic radiation and absorption in relativistic plasma on astrophysics objects, where superhigh magnetic field has a value of the order 108-109T, as well as for interpretation of experiments with trapped ions.

  20. An experimental investigation of a tandem relativistic backward wave oscillator-travelling wave tube amplifier system for generating high-power microwaves

    Microsoft Academic Search

    Gilberto Barreto

    1992-01-01

    The experimental investigation described in this dissertation demonstrates the feasibility of generating long (greater than or equal to 50 nsec) pulses of high-power (greater than or equal to 100 MW), X-band frequency microwaves. In these experiments, a relativistic Backward Wave Oscillator (BWO) is used in tandem with a Traveling Wave Tube (TWT) amplifier to generate microwave radiation. The tandem BWO

  1. On the coupling of blast wave theory with atomic excitation in low-energy laser-induced plasmas formed in gases

    Microsoft Academic Search

    P. Shah; A. Biswas; R. L. Armstrong; L. J. Radziemski

    1990-01-01

    Time-dependent intensities of the spectral lines emitted by laser-induced plasmas generated in several gases are presented. The time-resolved and spatially varying intensities of two once-ionized nitrogen lines were used to calculate radial temperature distribution of temperature within the plasma. A modified blast wave theory, in which ionization was included through the Saha equation and the equation of conservation of charge,

  2. Loss of Geosynchronous Relativistic Electrons By Emic Wave Scattering Under Quiet Geomagnetic Conditions

    NASA Astrophysics Data System (ADS)

    Kim, K. H.; Hyun, K.; Lee, E.; Lee, D. H.

    2014-12-01

    We have examined relativistic electron flux losses at geosynchronous orbit under quiet geomagnetic conditions. One 3-day period, from 11 to 13 October 2007, was chosen for analysis because geomagnetic conditions were very quiet (3-day average of Kp < 1), and significant losses of geosynchronous relativistic electrons were observed. During this interval, there was no geomagnetic storm activity. Thus, the loss processes associated with geomagnetic field modulations caused by ring current buildup can be excluded. The >2 MeV electron flux at geosynchronous orbit shows typical diurnal variations with a maximum near noon and a minimum near midnight for each day. The flux level of the daily variation significantly decreased from first day to third day for the 3-day period by a factor of >10. The total magnetic field strength (BT) of the daily variation on the third day, however, is comparable to that on the first day. Unlike electron flux decreases, the flux of protons with energies between 0.8 and 4 MeV adiabatically responses to the daily variation of BT. That is, there is no significant decrease of the proton flux when the electron flux decreases. During the interval of quiet geomagnetic conditions, well-defined electromagnetic ion cyclotron (EMIC) waves were detected at geosynchronous spacecraft. Low-altitude polar orbiting spacecraft observed the precipitation of energetic protons and relativistic electrons in the interval of EMIC waves enhancement. From these observations, we suggest that the EMIC waves at geosynchronous orbit cause pitch-angle scattering and electron loss to the atmosphere under quiet geomagnetic conditions.

  3. Interaction of relativistically strong electromagnetic waves with a layer of overdense plasma

    SciTech Connect

    Korzhimanov, A. V.; Eremin, V. I., E-mail: eremin@ufp.appl.sci-nnov.ru; Kim, A. V. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Tushentsov, M. R. [University of Texas at Austin (United States)

    2007-10-15

    Plasma-field structures that arise under the interaction between a relativistically strong electromagnetic wave and a layer of overdense plasma are considered within a quasistationary approximation. It is shown that, together with known solutions, which are nonlinear generalizations of skin-layer solutions, multilayer structures containing cavitation regions with completely removed electrons (ion layers) can be excited when the amplitude of the incident field exceeds a certain threshold value. Under symmetric irradiation, these cavitation regions, which play the role of self-consistent resonators, may amplify the field and accumulate electromagnetic energy.

  4. Role of helmet in the mechanics of shock wave propagation under blast loading conditions.

    PubMed

    Ganpule, S; Gu, L; Alai, A; Chandra, N

    2012-01-01

    The effectiveness of helmets in extenuating the primary shock waves generated by the explosions of improvised explosive devices is not clearly understood. In this work, the role of helmet on the overpressurisation and impulse experienced by the head were examined. The shock wave-head interactions were studied under three different cases: (i) unprotected head, (ii) head with helmet but with varying head-helmet gaps and (iii) head covered with helmet and tightly fitting foam pads. The intensification effect was discussed by examining the shock wave flow pattern and verified with experiments. A helmet with a better protection against shock wave is suggested. PMID:21806412

  5. Interaction of Supernova Blast Waves with Interstellar Clouds: Experiments on the Omega Laser

    Microsoft Academic Search

    R I Klein; H F Robey; T S Perry; J O Kane; J A Greenough; M M Marinak

    2001-01-01

    The interaction of strong shock waves, such as those generated by the explosion of supernovae with interstellar clouds, is a problem of fundamental importance in understanding the evolution and the dynamics of the interstellar medium (ISM) as it is disrupted by shock waves. The physics of this essential interaction is critical to understanding the evolution of the ISM, the mixing

  6. The Production of Strong Blast Waves through Intense Laser Irradiation of Atomic Clusters

    Microsoft Academic Search

    T. Ditmire; K. Shigemori; B. A. Remington; K. Estabrook; R. A. Smith

    2000-01-01

    An understanding of radiation effects on the evolution of shock waves is of great importance to many problems in astrophysics. Shock waves driven by a laser-heated plasma are attractive for laboratory investigation of these phenomena. Recent studies of intense short-pulse laser interactions with gases of atomic clusters indicate a potential avenue to access this regime of radiative hydrodynamics. We have

  7. Drift-Resonant Interaction of Magnetospheric Relativistic Electrons with Ultra-Low Frequency (ULF) Waves: Comparison between Observations and Simulations

    NASA Astrophysics Data System (ADS)

    Shao, X.; Fung, S.; Tan, L.; Papadopoulos, K.

    2007-12-01

    By analyzing CRRES and GOES observations on Aug. 27 1991, Tan et al. [2004] reported evidence of magnetospheric relativistic electron acceleration by resonant interactions with PC5 ULF waves. The event showed strong ULF wave activities after a storm sudden commencement (SSC) and energetic electron fluxes were enhanced in 2 hours. The electron flux peak observed in energy channels (0.6 - 1.1 MeV) were modulated by local electric field observed by CRRES. In this study, we set up a drift-resonant interaction model between ULF wave and magnetospheric relativistic electrons to model the observed electron flux in the event. In this model, the poloidal mode wave is concentrated in the dayside and the toroidal mode wave is concentrated in two flanks. The toroidal mode waves in the dawn and dusk flanks are in anti-phase. We found that electron can be accelerated jointly by the poloidal wave in the dayside and toroidal wave in flanks. The dayside poloidal wave serves as the dominant source of electron acceleration. The simulated electron flux variations agree well with observations both in fine details and long period behavior. These agreements in electron behavior indicate that the ULF wave plays an important role in accelerating MeV relativistic electrons around the geosynchronous orbit. General applications of the model during SSC events are also discussed. Tan, L. C., S. F. Fung, and X. Shao, Observation of magnetospheric relativistic electrons accelerated by Pc-5 ULF waves, Geophys. Rev. Lett., L14802, doi: 10.1029/2004GL019459, 2004.

  8. An overmoded relativistic backward wave oscillator with efficient dual-mode operation

    SciTech Connect

    Xiao, Renzhen; Li, Jiawei; Bai, Xianchen; Song, Zhimin; Teng, Yan; Ye, Hu; Li, Xiaoze; Sun, Jun; Chen, Changhua [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Zhang, Xiaowei [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Key Laboratory of Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049 (China)

    2014-03-03

    A dual-mode operation mechanism in an overmoded relativistic backward wave oscillator is presented. The electron beam interacts with the ?1st space harmonic of TM{sub 01} mode synchronously in the slow wave structure. Then the backward propagating TM{sub 01} mode is converted to the forward propagating TM{sub 02} mode. As the phase velocity of the volume harmonic of TM{sub 02} mode is about twice that of the surface harmonic of TM{sub 01} mode, the TM{sub 02} mode also plays an important role in the high-power microwave generation. Particle-in-cell simulation shows that an efficiency of 48% and a significant improvement of the power capacity have been obtained.

  9. Relativistic magnetosonic shock waves in synchrotron sources - Shock structure and nonthermal acceleration of positrons

    NASA Technical Reports Server (NTRS)

    Hoshino, Masahiro; Arons, Jonathan; Gallant, Yves A.; Langdon, A. B.

    1992-01-01

    The theoretical properties of relativistic, transverse, magnetosonic collisionless shock waves in electron-positron-heavy ion plasmas of relevance to astrophysical sources of synchrotron radiation are investigated. Both 1D electromagnetic particle-in-cell simulations and quasi-linear theory are used to examine the spatial and kinetic structure of these nonlinear flows. A new process of shock acceleration of nonthermal positrons, in which the gyrating reflected heavy ions dissipate their energy in the form of collectively emitted, left-handed magnetosonic waves which are resonantly absorbed by the positrons immediately behind the ion reflection region, is described. Applications of the results to the termination shocks of pulsar winds and to the termination shocks of jets emanating from the AGN are outlined.

  10. Investigation of EMIC Wave Scattering as the Cause for the BARREL January 17, 2013 Relativistic Electron Precipitation Event

    NASA Astrophysics Data System (ADS)

    Li, Z.; Millan, R. M.; Hudson, M. K.; Woodger, L. A.; Fennell, J. F.; Engebretson, M. J.; MacDonald, E.

    2013-12-01

    Scattering by electromagnetic ion cyclotron (EMIC) waves has been suggested to be a major cause of relativistic electron precipitation (REP). This mechanism has also been proposed as the cause for REP observed by balloon-borne detectors predominantly in the dusk sector. Observations from the recent BARREL balloon campaign, along with simultaneous detailed spacecraft measurements of waves and plasma conditions, give us an unprecedented opportunity to investigate this mechanism. We simulate relativistic electron pitch-angle diffusion by EMIC waves using wave and particle data measured by GOES and the Van Allen Probes, and compare the energy distribution of the resulting precipitation with BARREL observations of precipitation made on January 17, 2013. This comparison sheds light on the role of EMIC waves in causing REP as well as the effectiveness of the quasi-linear model.

  11. Fluid\\/Structure Interaction Computational Investigation of Blast-Wave Mitigation Efficacy of the Advanced Combat Helmet

    Microsoft Academic Search

    M. Grujicic; W. C. Bell; B. Pandurangan; P. S. Glomski

    2011-01-01

    To combat the problem of traumatic brain injury (TBI), a signature injury of the current military conflicts, there is an urgent need to design head protection systems with superior blast\\/ballistic impact mitigation capabilities. Toward that end, the blast impact mitigation performance of an advanced combat helmet (ACH) head protection system equipped with polyurea suspension pads and subjected to two different

  12. Annihilation Rate of Heavy 0^{++} P-wave Quarkonium in Relativistic Salpeter Method

    E-print Network

    Guo-Li Wang

    2007-08-26

    Two-photon and two-gluon annihilation rates of P-wave scalar charmonium and bottomonium up to third radial excited states are estimated in the relativistic Salpeter method. We solved the full Salpeter equation with a well defined relativistic wave function and calculated the transition amplitude using the Mandelstam formalism. Our model dependent estimates for the decay widths: $\\Gamma(\\chi_{c0} \\to 2\\gamma)=3.78$ keV, $\\Gamma(\\chi'_{c0} \\to 2\\gamma)=3.51$ keV, $\\Gamma(\\chi_{b0} \\to 2\\gamma)=48.8$ eV and $\\Gamma(\\chi'_{b0} \\to 2\\gamma)=50.3$ eV. We also give estimates of total widths by the two-gluon decay rates: $\\Gamma_{tot}(\\chi_{c0})=10.3$ MeV, $\\Gamma_{tot}(\\chi'_{c0})=9.61$ MeV, $\\Gamma_{tot}(\\chi_{b0})=0.887$ MeV and $\\Gamma_{tot}(\\chi'_{b0})=0.914$ MeV.

  13. Transition to Turbulence and Effect of Initial Conditions on 3D Compressible Mixing in Planar Blast-wave-driven Systems

    SciTech Connect

    Miles, A R; Edwards, M J; Greenough, J A

    2004-11-08

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams, 9(2), 209 (1991)] are presented. Using the multi-physics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J.A. Greenough, J. Comp. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pre-transition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernova are discussed.

  14. Observation and modeling of mixing-layer development in high-energy-density, blast-wave-driven shear flow

    SciTech Connect

    Di Stefano, C. A., E-mail: carlosds@umich.edu; Kuranz, C. C.; Klein, S. R.; Drake, R. P. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Malamud, G. [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States) [Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Physics, Nuclear Research Center-Negev, Beer-Sheva (Israel); Henry de Frahan, M. T.; Johnsen, E. [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Shimony, A.; Shvarts, D. [Department of Physics, Nuclear Research Center-Negev, Beer-Sheva (Israel) [Department of Physics, Nuclear Research Center-Negev, Beer-Sheva (Israel); Department of Physics, Ben-Gurion University, Beer-Sheva (Israel); Smalyuk, V. A.; Martinez, D. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)] [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

    2014-05-15

    In this work, we examine the hydrodynamics of high-energy-density (HED) shear flows. Experiments, consisting of two materials of differing density, use the OMEGA-60 laser to drive a blast wave at a pressure of ?50 Mbar into one of the media, creating a shear flow in the resulting shocked system. The interface between the two materials is Kelvin-Helmholtz unstable, and a mixing layer of growing width develops due to the shear. To theoretically analyze the instability's behavior, we rely on two sources of information. First, the interface spectrum is well-characterized, which allows us to identify how the shock front and the subsequent shear in the post-shock flow interact with the interface. These observations provide direct evidence that vortex merger dominates the evolution of the interface structure. Second, simulations calibrated to the experiment allow us to estimate the time-dependent evolution of the deposition of vorticity at the interface. The overall result is that we are able to choose a hydrodynamic model for the system, and consequently examine how well the flow in this HED system corresponds to a classical hydrodynamic description.

  15. Diffusion of Cosmic Rays in a Multiphase Interstellar Medium Swept-Up by a Supernova Remnant Blast Wave

    E-print Network

    Roh, Soonyoung; Inoue, Tsuyoshi

    2015-01-01

    Supernova remnants (SNRs) are one of the most energetic astrophysical events and are thought to be the dominant source of Galactic cosmic rays (CRs). A recent report on observations from the Fermi satellite has shown a signature of pion decay in the gamma-ray spectra of SNRs. This provides strong evidence that high-energy protons are accelerated in SNRs. The actual gamma-ray emission from pion decay should depend on the diffusion of CRs in the interstellar medium. In order to quantitatively analyse the diffusion of high-energy CRs from acceleration sites, we have performed test particle numerical simulations of CR protons using a three-dimensional magnetohydrodynamics (MHD) simulation of an interstellar medium swept-up by a blast wave. We analyse the diffusion of CRs at a length scale of order a few pc in our simulated SNR, and find the diffusion of CRs is precisely described by a Bohm diffusion, which is required for efficient acceleration at least for particles with energies above 30 TeV for a realistic int...

  16. Theoretical analysis of a thermal plasma-loaded relativistic traveling wave tube having corrugated slow wave structure with solid electron beam

    NASA Astrophysics Data System (ADS)

    Javadi, Zahra; Saviz, Shahrooz

    2015-01-01

    A relativistic traveling wave tube with thermal plasma-filled corrugated waveguide is driven by a finite solid electron beam with the entire system immersed in a strong longitudinal magnetic field that magnetized plasma and electron beam. The dispersion relation for the relativistic traveling wave tube is obtained by linear fluid theory. The numerical results show that the growth rate decreases by increasing plasma temperature, waveguide radius, plasma density and electron beam energy. As show in this paper the effect of electron beam density and corrugation period is to increase growth rate.

  17. A millimeter wave relativistic backward wave oscillator operating in TM03 mode with low guiding magnetic field

    NASA Astrophysics Data System (ADS)

    Ye, Hu; Teng, Yan; Chen, Changhua; Ning, Hui; Song, Zhimin; Cao, Yibing; Wu, Ping

    2015-06-01

    A V-band overmoded relativistic backward wave oscillator (RBWO) guided by low magnetic field and operating on a TM03 mode is presented to increase both the power handling capacity and the wave-beam interaction conversion efficiency. Trapezoidal slow wave structures (SWSs) with shallow corrugations and long periods are adopted to make the group velocity of TM03 mode at the intersection point close to zero. The coupling impedance and diffraction Q-factor of the RBWO increase, while the starting current decreases owing to the reduction of the group velocity of TM03 mode. In addition, the TM03 mode dominates over the other modes in the startup of the oscillation. Via numerical simulation, the generation of the microwave pulse with an output power of 425 MW and a conversion efficiency of 32% are achieved at 60.5 GHz with an external magnetic field of 1.25 T. This RBWO can provide greater power handling capacity when operating on the TM03 mode than on the TM01 mode.

  18. Blood brain barrier dysfunction and delayed neurological deficits in mild traumatic brain injury induced by blast shock waves

    PubMed Central

    Shetty, Ashok K.; Mishra, Vikas; Kodali, Maheedhar; Hattiangady, Bharathi

    2014-01-01

    Mild traumatic brain injury (mTBI) resulting from exposure to blast shock waves (BSWs) is one of the most predominant causes of illnesses among veterans who served in the recent Iraq and Afghanistan wars. Such mTBI can also happen to civilians if exposed to shock waves of bomb attacks by terrorists. While cognitive problems, memory dysfunction, depression, anxiety and diffuse white matter injury have been observed at both early and/or delayed time-points, an initial brain pathology resulting from exposure to BSWs appears to be the dysfunction or disruption of the blood-brain barrier (BBB). Studies in animal models suggest that exposure to relatively milder BSWs (123 kPa) initially induces free radical generating enzymes in and around brain capillaries, which enhances oxidative stress resulting in loss of tight junction (TJ) proteins, edema formation, and leakiness of BBB with disruption or loss of its components pericytes and astrocyte end-feet. On the other hand, exposure to more intense BSWs (145–323 kPa) causes acute disruption of the BBB with vascular lesions in the brain. Both of these scenarios lead to apoptosis of endothelial and neural cells and neuroinflammation in and around capillaries, which may progress into chronic traumatic encephalopathy (CTE) and/or a variety of neurological impairments, depending on brain regions that are afflicted with such lesions. This review discusses studies that examined alterations in the brain milieu causing dysfunction or disruption of the BBB and neuroinflammation following exposure to different intensities of BSWs. Furthermore, potential of early intervention strategies capable of easing oxidative stress, repairing the BBB or blocking inflammation for minimizing delayed neurological deficits resulting from exposure to BSWs is conferred. PMID:25165433

  19. Why galactic gamma-ray bursts might depend on environment: Blast waves around neutron stars

    NASA Technical Reports Server (NTRS)

    Rees, Martin J.; Meszaros, Peter; Begelman, Mitchell C.

    1994-01-01

    Although galactic models for gamma-ray bursts are hard to reconcile with the isotropy data, the issue is still sufficiently open that both options should be explored. The most likely 'triggers' for bursts in our Galaxy would be violent disturbances in the magnetospheres of neutron stars. Any event of this kind is likely to expel magnetic flux and plasma at relativistic speed. Such ejecta would be braked by the interstellar medium (ISM), and a gamma-ray flash may result from this interaction. The radiative efficiency, of this mechanism would depend on the density of the circumstellar ISM. Therefore, even if neutron stars were uniformly distributed in space (at least within 1-2 kpc of the Sun), the observed locations of bursts would correlate with regions of above-average ISM density.

  20. Underwater blast wave pressure sensor based on polymer film fiber Fabry-Perot cavity.

    PubMed

    Wang, Junjie; Wang, Meng; Xu, Jian; Peng, Li; Yang, Minghong; Xia, Minghe; Jiang, Desheng

    2014-10-01

    This paper describes the theoretical and experimental aspects of an optical underwater shock wave sensor based on a polymer film optical fiber Fabry-Perot cavity manufactured by vacuum deposition technology. The transduction mechanism of the sensor involves a normally incident acoustic stress wave that changes the thickness of the polymer film, thereby giving rise to a phase shift. This transient interferometric phase is interrogated by a three-phase-step algorithm. Theoretically, the sensor-acoustic-field interaction principle is analyzed, and the phase modulation sensitivity based on the theory of waves in the layered media is calculated. Experimentally, a static calibration test and a dynamic calibration test are conducted using a piston-type pressure calibration machine and a focusing-type electromagnetic shock wave. Results indicate that the repeatability, hysteresis, nonlinearity, and the overall measurement accuracy of the sensor within the full pressure range of 55 MPa are 1.82%, 0.86%, 1.81%, and 4.49%, respectively. The dynamic response time is less than 0.767 ?s. Finally, three aspects that need further study for practical use are pointed out. PMID:25322237

  1. Modelling of blast loading on aboveground structures - I. General phenomenology and external blast

    Microsoft Academic Search

    F. B. A. Beshara

    1994-01-01

    The paper is concerned with the prediction of dynamic effects of unconfined explosions needed for the structural analysis of blast-loaded aboveground structures. The basic features of the explosion and blast wave phenomena are presented along with a discussion of TNT equivalency and blast scaling laws. The characteristics of incident overpressure loading due to atomic weapons, conventional high explosives and unconfined

  2. A Experimental Investigation of a Tandem Relativistic Backward Wave Oscillator - Travelling Wave Tube Amplifier System for Generating High-Power Microwaves

    Microsoft Academic Search

    Gilberto Barreto

    1992-01-01

    The experimental investigation described in this dissertation demonstrates the feasibility of generating long (>=50 nsec) pulses of high-power (>=100 MW), X-band frequency microwaves. In these experiments, a relativistic Backward Wave Oscillator (BWO) is used in tandem with a Traveling Wave Tube (TWT) amplifier to generate microwave radiation. The tandem BWO-TWT system is driven in the TM_{01 } mode by a

  3. A Ka-band TM02 mode relativistic backward wave oscillator with cascaded resonators

    NASA Astrophysics Data System (ADS)

    Teng, Yan; Cao, Yinbin; Song, Zhimin; Ye, Hu; Shi, Yanchao; Chen, Changhua; Sun, Jun

    2014-12-01

    By combining the Cerenkov-type generator with the cascaded resonators, this paper proposes a Ka-band relativistic backward wave oscillator operating under the guide magnetic field 1.0 T with high power handling capability and high conversion efficiency. It is found that TM02 can be selected as the operation mode in order to increase the power handling capability and provide sufficient coupling with the electron beam. In slow wave structure (SWS), ripples composed of semicircle on top of the rectangle enhance the wave-beam interaction and decrease the intensity of the electric field on the metallic surface. Taking advantage of the resonator cascades, the output power and the conversion efficiency are promoted greatly. The front cascaded resonators efficiently prevent the power generated in SWS from leaking into the diode region, and quicken the startup of the oscillation due to the premodulation of the beam. However, the post cascade slightly postpones the startup because of the further energy extraction from the electron beam. The numerical simulation shows that generation with power 514 MW and efficiency 41% is obtained under the diode voltage 520 kV and current 2.4 kA. And the microwave with the pure frequency spectrum of 29.35 GHz radiates in the pure TM01 mode.

  4. Investigation of an improved relativistic backward wave oscillator in efficiency and power capacity

    SciTech Connect

    Song, W.; Chen, C. H.; Sun, J.; Zhang, X. W.; Shao, H.; Song, Z. M.; Huo, S. F.; Shi, Y. C.; Li, X. Z. [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an, Shaanxi 710024 (China)

    2012-10-15

    Investigation of relativistic backward wave oscillator with high efficiency and power capacity is presented in this paper. To obtain high power and high efficiency, a TM{sub 021} mode resonant reflector is used to reduce the pulse shortening and increase power capacity to about 1.7 times. Meanwhile, an extraction cavity at the end of slow wave structure is employed to improve the efficiency from less than 30% to over 40%, through the beam-wave interaction intensification and better energy conversion from modulated electron beam to the electromagnetic field. Consistent with the numerical results, microwave with a power of 3.2 GW, a frequency of 9.75 GHz, and a pulse width of 27 ns was obtained in the high power microwave generation experiment, where the electron beam energy was configured to be {approx}910 kV and its current to be {approx}8.6 kA. The efficiency of the RBWO exceeds 40% at a voltage range of 870 kV-1000 kV.

  5. Dynamics of ionization wave produced by relativistic electron beam inside a glass target

    NASA Astrophysics Data System (ADS)

    Leblanc, P.; Sentoku, Y.; Ivanov, V. V.; Yates, K.; Wiewior, P.; Kindel, J.; Sarkisov, G. S.; Jobe, D.; Spielman, R.; Bychenkov, V. Yu.

    2010-11-01

    Recent laser-matter experiments have revealed interesting features of the motion of electrons at the front of an ionization wave propagating inside a solid density silica glass target. Using an ultra-intense ultra-short pulse laser, highly relativistic electrons were created in the interaction region at the interface of the glass and were subsequently accelerated longitudinally inside the target. Results showed the ionization bubble inside the target expanding anisotropically with a heavy bias towards the lateral direction after a few picoseconds. Furthermore, electrons at the front of the ionization wave appeared to curve back on themselves creating a ``fountain effect.'' Using a 2D particle-in-cell code capable of resolving collisions and ionization of solid density materials, we simulated a scaled version of this experiment and show the anisotropic expansion bias as well as the electron fountain effect. Analysis of the results reveal a very strong buildup of the electrostatic field at the front of the ionization wave due to strong gradients in the longitudinal current. Fast free electrons respond to the field buildup by curving outwards and back upstream with respect to the path of the laser beam.

  6. Interaction of Supernova Blast Waves with Interstellar Clouds: Experiments on the Omega Laser

    SciTech Connect

    Klein, R I; Robey, H F; Perry, T S; Kane, J O; Greenough, J A; Marinak, M M

    2001-08-17

    The interaction of strong shock waves, such as those generated by the explosion of supernovae with interstellar clouds, is a problem of fundamental importance in understanding the evolution and the dynamics of the interstellar medium (ISM) as it is disrupted by shock waves. The physics of this essential interaction is critical to understanding the evolution of the ISM, the mixing of interstellar clouds with the ISM and the viability of this mechanism for triggered star formation. Here we present the results of a series of new OMEGA laser experiments investigating the evolution of a high density sphere embedded in a low density medium after the interaction of a strong shock wave, thereby emulating the supernova shock-cloud interaction. The interaction is viewed from two orthogonal directions enabling visualization of the both the initial distortion of the sphere into a vortex ring as well as the onset of an azimuthal instability that ultimately results in the three-dimensional breakup of the ring. These studies augment previous studies [1,2] on the NOVA laser by enabling the full three-dimensional topology of the interaction to be understood. We show that the experimental results for the vortex ring are in remarkable agreement with the incompressible theory of Widnall [3]. Implications for mixing in the ISM are discussed.

  7. Fluid\\/Structure Interaction Computational Investigation of Blast-Wave Mitigation Efficacy of the Advanced Combat Helmet

    Microsoft Academic Search

    M. Grujicic; W. C. Bell; B. Pandurangan; P. S. Glomski

    To combat the problem of traumatic brain injury (TBI), a signature injury of the current military conflicts, there is an urgent\\u000a need to design head protection systems with superior blast\\/ballistic impact mitigation capabilities. Toward that end, the\\u000a blast impact mitigation performance of an advanced combat helmet (ACH) head protection system equipped with polyurea suspension\\u000a pads and subjected to two different

  8. Electron acceleration in relativistic plasma waves generated by a single frequency short-pulse laser

    SciTech Connect

    Coverdale, C.A.; Darrow, C.B.; Decker, C.D. [Lawrence Livermore National Lab., CA (United States); Mori, W.B.; Tzeng, K.C., Clayton, C.E.; Marsh, K.A.; Joshi, C. [California Univ., Los Angeles, CA (United States)

    1995-04-27

    Experimental evidence for the acceleration of electrons in a relativistic plasma wave generated by Raman forward scattering (SRS-F) of a single-frequency short pulse laser are presented. A 1.053 {mu}m, 600 fsec, 5 TW laser was focused into a gas jet with a peak intensity of 8{times}10{sup 17} W/cm{sup 2}. At a plasma density of 2{times}10{sup 19} cm{sup {minus}3}, 2 MeV electrons were detected and their appearance was correlated with the anti-Stokes laser sideband generated by SRS-F. The results are in good agreement with 2-D PIC simulations. The use of short pulse lasers for making ultra-high gradient accelerators is explored.

  9. Gravitational waves from relativistic neutron star mergers with nonzero-temperature equations of state

    E-print Network

    R. Oechslin; H. -T. Janka

    2007-08-08

    We analyze the gravitational wave (GW) emission from our recently published set of relativistic neutron star (NS) merger simulations and determine characteristic signal features that allow one to link GW measurements to the properties of the merging binary stars. We find that the distinct peak in the GW energy spectrum that is associated with the formation of a hypermassive merger remnant has a frequency that depends strongly on the properties of the nuclear equation of state (EoS) and on the total mass of the binary system, whereas the mass ratio and the NS spins have a weak influence. If the total mass can be determined from the inspiral chirp signal, the peak frequency of the postmerger signal is a sensitive indicator of the EoS.

  10. Do fireballs in the interstellar medium necessarily imply blast wave propagation?

    NASA Astrophysics Data System (ADS)

    Mitra, A.

    1996-09-01

    The current version of cosmic fireball (FB) models for understanding the mechanism of Gamma Ray Bursts (GRBs), expounded by Meszaros, Rees and their coworkers (MRC), envisage that the initial leptonic fire-ball energy is converted into bulk kinetic energy of the polluting baryons and which decelerate by interacting with the interstellar medium (ISM) and form a forward shock. From elementary, yet hitherto overlooked, considerations we show that the relativistic baryons (protons) are unlikely to see the standard ISM as a fluid and interact efficiently with it on the acceptable GRB time scales (0.1-100s). If we invoke the known value of the ISM spatial diffusion coefficient in the present problem, we need to assume the existence of very strong magnetic field (~104G) at the BF-ISM interface to alleviate this foregoing problem. Alternatively, we must assume that there is indeed strong magnetic turbulence near the interface and the scattering lengh is directly determined by the much shorter value of the gyro-radii of the protons. Simultaneously, we need to assume that substantial fraction of the FB energy is converted into magnetic field and remains frozen into the BF to a yield a value of the magnetic field ~0.1G near the expected deceleration radius (r_d_~10^15^-10^16^cm). Still it turns out to be far from clear how the BF-ISM interaction can indeed be seen as a collision between two fluids and occuring on a time scale shorter than the expected GRB time scales.

  11. MHD Simulation of the Excitation of Compressional Mode ULF Waves and the Implied Magnetospheric Relativistic Electron Acceleration

    NASA Astrophysics Data System (ADS)

    Shao, X.; Tan, L. C.; Fung, S. F.; Vassiliadis, D.; Sharma, A. S.

    2011-12-01

    Recent work of Tan et al. [2011] found evidence of relativistic electron acceleration by the compressional-mode ULF waves during a storm sudden commencement event on September 25, 2001 from the observations by four Cluster spacecraft measuring ULF waves and low-energy electron flux, and five LANL spacecraft measuring energetic electron fluxes over a wide energy range. We perform global MHD simulation through NASA/CCMC to investigate the excitation and distribution of compressional ULF waves during the event. Comparison with satellite and ground observations are given. In this event, the energetic electron flux measured by LANL shows modulation of low-energy electrons and acceleration of high-energy electrons by the compressional poloidal-mode electric field oscillations within 2-3 hours. Implication of simulated ULF wave distribution for relativistic electron acceleration will be discussed. Tan, L. C., X. Shao, A. S. Sharma, and S. F. Fung (2011), Relativistic electron acceleration by compressional-mode ULF waves: Evidence from correlated Cluster, Los Alamos National Laboratory spacecraft, and ground-based magnetometer measurements, J. Geophys. Res., 116, A07226, doi:10.1029/2010JA016226.

  12. On the multistream approach of relativistic Weibel instability. II. Bernstein-Greene-Kruskal-type waves in magnetic trapping

    NASA Astrophysics Data System (ADS)

    Ghizzo, A.

    2013-08-01

    The stationary state with magnetically trapped particles is investigated at the saturation of the relativistic Weibel instability, within the "multiring" model in a Hamiltonian framework. The multistream model and its multiring extension have been developed in Paper I, under the assumption that the generalized canonical momentum is conserved in the perpendicular direction. One dimensional relativistic Bernstein-Greene-Kruskal waves with deeply trapped particles are addressed using similar mathematical formalism developed by Lontano et al. [Phys. Plasmas 9, 2562 (2002); Phys. Plasmas 10, 639 (2003)] using several streams and in the presence of both electrostatic and magnetic trapping mechanisms.

  13. Factors influencing the microwave pulse duration in a klystron-like relativistic backward wave oscillator

    NASA Astrophysics Data System (ADS)

    Xiao, Renzhen; Zhang, Xiaowei; Zhang, Ligang; Li, Xiaoze; Zhang, Lijun

    2012-07-01

    In this paper, we analyze the factors that affect the microwave pulse duration in a klystron-like relativistic backward wave oscillator (RBWO), including the diode voltage, the guiding magnetic field, the electron beam collector, the extraction cavity, and the gap between the electron beam and the slow wave structure (SWS). The results show that the microwave pulse duration increases with the diode voltage until breakdown occurs on the surface of the extraction cavity. The pulse duration at low guiding magnetic field is generally 5-10 ns smaller than that at high magnetic field due to the asymmetric electron emission and the larger energy spread of the electron beam. The electron beam collector can affect the microwave pulse duration significantly because of the anode plasma generated by bombardment of the electron beam on the collector surface. The introduction of the extraction cavity only slightly changes the pulse duration. The decrease of the gap between the electron beam and the SWS can increase the microwave pulse duration greatly.

  14. Factors influencing the microwave pulse duration in a klystron-like relativistic backward wave oscillator

    SciTech Connect

    Xiao Renzhen; Zhang Xiaowei; Zhang Ligang; Li Xiaoze; Zhang Lijun [National Key Laboratory of Science and Technology on High Power Microwave, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

    2012-07-15

    In this paper, we analyze the factors that affect the microwave pulse duration in a klystron-like relativistic backward wave oscillator (RBWO), including the diode voltage, the guiding magnetic field, the electron beam collector, the extraction cavity, and the gap between the electron beam and the slow wave structure (SWS). The results show that the microwave pulse duration increases with the diode voltage until breakdown occurs on the surface of the extraction cavity. The pulse duration at low guiding magnetic field is generally 5-10 ns smaller than that at high magnetic field due to the asymmetric electron emission and the larger energy spread of the electron beam. The electron beam collector can affect the microwave pulse duration significantly because of the anode plasma generated by bombardment of the electron beam on the collector surface. The introduction of the extraction cavity only slightly changes the pulse duration. The decrease of the gap between the electron beam and the SWS can increase the microwave pulse duration greatly.

  15. Purification of the output modes of overmoded relativistic backward wave oscillators

    SciTech Connect

    Zhang, Dian; Zhang, Jun; Zhong, Huihuang; Jin, Zhenxing; Yuan, Yuzhang [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)] [College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-02-15

    Successful suppression of mode competition in the beam-wave interaction process of overmoded relativistic backward wave oscillators (RBWOs) cannot ensure the output modes purity. Optimizing the magnitude and the phase of the mode conversion coefficients in the devices is significant for purifying the output modes. A universal method of purifying the TM{sub 01} and TM{sub 02} mixed modes output by overmoded RBWOs without decreasing the total output power is presented in this paper. With this method, we purify the TM{sub 01} and TM{sub 02} mixed modes generated in an X-band overmoded RBWO (D/????2.6) operated at the constant diode voltage of 730?kV. Dependence of modes purification effect on the variation of diode voltage is also analyzed in particle-in-cell simulation. Our analysis indicates that when the diode voltage is in the range of (730 ± 60) kV, the percentage of output power carried by TM{sub 01} mode will be higher than 95%.

  16. Electron Acceleration and Space- and frequency-resolved diagnostics of plasma waves in relativistically guided channels

    NASA Astrophysics Data System (ADS)

    Clayton, C. E.

    1997-11-01

    Prior results from this ongoing collaborative experiment using the 25 TW, < 1 ps Vulcan Laser at RAL have shown plasma waves driven to "wavebreaking" via the forward Raman scattering instability, an inferred minimum acceleration gradient of > 160 GeV/m from > 100 MeV electrons (well over the linear dephasing limit) over a measured 600 ? m interaction length, and a high (0.1%) conversion of the pump light into forward-going second harmonic light from the transverse density gradients of a plasma channel which extending over several Rayleigh lengths Z_r. A new set of space- and spectrally-resolving diagnostics were employed in a recent experiment. Most notably, an external probe beam was used to generate a spectrally-resolve image of the relativistic plasma waves responsible for the high energy electrons. Laser self-channeling evidenced by the large plasma waves across the entire 4 mm gas jet plume (12 Z_r) was a common occurrence and electron spectra typically extended out to ? 40 MeV in this case. However, on some shots where the electron spectra extended out to 100 MeV, the acceleration length was 7 times shorter. This channel termination could be due to catastrophic wavebreaking, partition laser energy into a larger k-space and plasma heating. footnote In collaboration with D. Gordon, P. Muggli, K. C. Tzeng, W. B. Mori, and C. Joshi of UCLA; V. Malka of LULI, Ecole Polytechique; Z. Najmudin, A. Modena, and A. E. Dangor of Imperial College, London and with the staff of the Vulcan Laser Center, Rutherford Appleton Laboratory (RAL), UK. Work supported by the EPSRC, DOE, EU, and LULI/DRAL.

  17. Gravitational waves and the deformation of compact objects: Topics in relativistic astrophysics

    NASA Astrophysics Data System (ADS)

    Johnson-McDaniel, Nathan Kieran

    In this dissertation, we present various theoretical investigations of sources of gravitational waves, relevant to interpreting the data from current and planned gravitational wave detectors; an idee fixe is the deformation of compact objects. We begin in the strong field, vacuum regime, with a construction of initial data for the numerical simulation of black hole binaries (specializing to the case of nonspinning holes in a quasicircular orbit). The data we construct contain more of the binary's expected physics than any other current data set. In particular, they contain both the binary's outgoing radiation and the expected tidal deformations of the holes. Such improved initial data will likely be necessary for simulations to achieve the accuracy required to supply advanced gravitational wave detectors with templates for parameter estimation. We end in the weak field, hydrodynamic regime with a calculation of the expected accuracy with which one can combine standard electromagnetic and gravitational wave observations of white dwarf binaries to measure the masses of the binary's components. In particular, we show that this measurement will not be contaminated by finite size effects for realistic sources observed by LISA, though such effects could be important for exceptional sources and/or advanced mHz gravitational wave detectors. In the middle, we make a detour into the messy and poorly constrained realm of the physics of neutron star interiors, calculating the shear modulus of hadron--quark mixed phase in hybrid stars. Here we include a rough treatment of charge screening, dimensional continuation of the lattice, and the contributions from changing the cell volume when shearing lowerdimensional lattices. We find that the last of these contributions is necessary to stabilize the lattice for those dimensions, where it makes a considerable contribution to the shear modulus. We then move back to sounder theoretical footing in making a general relativistic calculation of the maximum elastic quadrupole deformation that could be sustained by a star with a known shear modulus and breaking strain (provided by, e.g., the hadron--quark mixed phase in the core, or the more standard lattice of nuclei in the crust). We find that the standard Newtonian calculation considerably overestimates the quadrupole, particularly for massive, compact stars. We also present the dimensionally continued Poisson summation formula we discovered while performing the shear modulus calculation, and thought interesting enough to prove rigorously. Our method of proof also provides a new way of proving other (Voronoi) summation formulae obtained from functions satisfying modular transformations, and allows one to relax certain of the standard hypotheses.

  18. Determination of the average ionization and thermodynamic regimes of xenon plasmas with an application to the characterization of blast waves launched in xenon clusters

    NASA Astrophysics Data System (ADS)

    Rodriguez, R.; Gil, J. M.; Florido, R.; Rubiano, J. G.; Mendoza, M. A.; Martel, P.; Minguez, E.; Symes, D. R.; Hohenberger, M.; Smith, R. A.

    2011-06-01

    Radiative shock waves play a pivotal role in the transport energy into the stellar medium. This fact has led to many efforts to scale the astrophysical phenomena to accessible laboratory conditions and their study has been highlighted as an area requiring further experimental investigations. Low density material with high atomic mass is suitable to achieve radiative regime, and, therefore, low density xenon gas is commonly used for the medium in which the radiative shock propagates. In this work the average ionization and the thermodynamic regimes of xenon plasmas are determined as functions of the matter density and temperature in a wide range of plasma conditions. The results obtained will be applied to characterize blast waves launched in xenon clusters.

  19. Long range correlations and the soft ridge in relativistic nuclear collisions

    SciTech Connect

    Gavin, Sean; Moschelli, George [Department of Physics and Astronomy, Wayne State University, 666 W. Hancock, Detroit, Michigan 48202 (United States); McLerran, Larry [Physics Department and RIKEN Brookhaven Research Center, Building 510A, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2009-05-15

    Relativistic Heavy Ion Collider experiments exhibit correlations peaked in relative azimuthal angle and extended in rapidity. Called the ridge, this peak occurs both with and without a jet trigger. We argue that the untriggered ridge arises when particles formed by flux tubes in an early Glasma stage later manifest transverse flow. Combining a blast wave model of flow fixed by single-particle spectra with a simple description of the Glasma, we find excellent agreement with current data.

  20. Characterization of the plasma column used in studies of plasma-loaded relativistic backward wave oscillator

    SciTech Connect

    Weaver, J.; Kobayashi, S.; Carmel, Y.; Rodgers, J.; Destler, W.W.; Granatstein, V.L. [Univ. of Maryland, College Park, MD (United States). Inst. for Plasma Research; Shkuvarunets, A. [Russian Academy of Science, Moscow (Russian Federation). General Physics Inst.

    1995-12-31

    A series of experiments were made to characterize the electron component of a transient plasma column immersed in magnetic field. These long plasma columns were used to fill the slow wave structure of a relativistic backward wave oscillator (BWO). The addition of plasma increased the efficiency of microwave generation, the operating frequency, and the maximum allowable beam current. The plasma was generated by a coaxial hydrogen flashover gun located just outside the solenoid on the center axis. The plasma electron radial and axial density profiles and the plasma electron temperature were studied over a range of magnetic fields, gun positions, and gun voltages. This knowledge will allow more precise control of the operating conditions of plasma-loaded BWOs. A single movable Langmuir probe and a cylindrical resonant cavity were used. The axial and radial density profiles were deduced from a large number of such measurements. These results were also compared to data gathered by an electromagnetic technique based on a plasma-loaded resonant cavity. The measured plasma electron density decreased from 10{sup 12} cm{sup {minus}3} to 10{sup 9} cm{sup {minus}3} in {approximately} 1 ms. The transverse profile of the column was bell-shaped with an effective radius on the order of 1 cm. Dependence of the peak value and the width of this distribution as a function of the magnetic field, gun voltage, and gun position will be presented. The measured plasma temperature was on the order of 1 eV for a typical shot.

  1. Nonlinear structure of ion-acoustic solitary waves in a relativistic degenerate electron-positron-ion plasma

    NASA Astrophysics Data System (ADS)

    Rasheed, A.; Tsintsadze, N. L.; Murtaza, G.; Chaudhary, R.

    2012-04-01

    Arbitrary amplitude and small amplitude ion-acoustic solitary waves (IASWs) have been investigated in a relativistic, collisionless, unmagnetized, and degenerate dense electron-positron-ion plasma. The arbitrary amplitude IASWs have been studied by using the Sagdeev-type pseudo-potential approach. Along with approximate solution, the exact amplitude solitary structure has also been studied numerically. The electrons and positrons are assumed to follow the corresponding Fermi distribution function and the ions are described by the hydrodynamic equations. A new dispersion relation for the ion-acoustic wave has been derived for the relativistic Thomas-Fermi plasma. An energy balance-like equation involving the Sagdeev-type pseudo-potential has been investigated and it has been shown that the concentration of plasma particles has significant effect on the permitted Mach number range of IASWs. Also, it has been pointed out that the only compressional supersonic IASWs can propagate in the relativistic Thomas-Fermi plasma. The present work would be helpful to understand the excitation of the nonlinear ion-acoustic waves in a degenerate plasma, such as in superdense white dwarfs and in the cores of massive planets.

  2. Photographs of Blast Effects on Structures

    NSDL National Science Digital Library

    Christopher Griffith

    This photograph collection shows a wood-frame house located 1,100 meters from ground zero, exposed to a nuclear blast at the Nevada Test Site. The test was Upshot-Knothole Annie, a 16 Kt tower shot, on March 17, 1953. Exposure to thermal radiation was 25 cal/cm2, about one-quarter of that experienced at ground zero in Hiroshima. The blast over pressure was 5 psi, and the blast wave created surface winds of 160 mph.

  3. Improved fundamental harmonic current distribution in a klystron-like relativistic backward wave oscillator by two pre-modulation cavities

    NASA Astrophysics Data System (ADS)

    Xiao, Renzhen; Chen, Changhua; Zhang, Xiaowei

    2013-04-01

    In a klystron-like relativistic backward wave oscillator, the velocity modulation is mainly obtained from the resonant reflector. By introducing two pre-modulation cavities between the input cavity and the resonant reflector, the amplitude and phase of density modulation can be adjusted relatively independently, to ensure an improved fundamental harmonic current distribution. Two peaks of harmonic current with high modulation coefficient of 1.2 appear in the second slow wave structure and the dual-cavity extractor and result in large beam energy losses in both regions. Particle-in-cell simulations show that a microwave with power of 11.5 GW and efficiency of 57% can be obtained.

  4. Five Years of Mid-Infrared Evolution of the Remnant of SN 1987A: The Encounter Between the Blast Wave and the Dusty Equatorial Ring

    NASA Technical Reports Server (NTRS)

    Dwek, Eli; Arendt, Richard G.; Bouchet, Patrice; Burrows, David N.; Challis, Peter; Danziger, I. John; De Buizer, James M.; Gehrz, Robert D.; Park, Sangwook; Polomski, Elisha F.; Slavin, Jonathan D.; Woodward, Charles E.

    2010-01-01

    We have used the Spitzer satellite to monitor the laid-IR evolution of SN 1987A over a 5 year period spanning the epochs between days 6000 and 8000 since the explosion. The supernova (SN) has evolved into a supernova remnant (SNR) and its radiative output, is dominated by the interaction of the SN blast wave with the pre-existing equatorial ring (ER). The mid-IR spectrum is dominated by emission from approximately 180 K silicate dust, collisionally-heated by the hot X-ray emitting gas with a temperature and density of 5 x 10(exp 6) K and approximately 3 x 10(exp 4) per cubic centimeter, respectively. The mass of the radiating dust is approximately 1.2 x 10(exp -6) solar mass on day 7554, and scales linearly with IR flux. Comparison of the IR data with the soft X-ray flux derived from Chandra observations shows that the IR-to-X-ray flux ratio, IRX, is roughly constant with a value of 2.5. Gas-grain collisions therefore dominate the cooling of the shocked gas. The constancy of IRX is most consistent with the scenario that very little grain processing or gas cooling have occurred throughout this epoch. The shape of the dust spectrum remained unchanged during the observations while the total flux increased by a factor of approximately 5 with a time dependence of t(sup '0.87 plus or minus 0.20), t' being the time since the first encounter between the blast wave and the ER. These observations are consistent with the transitioning of the blast wave from free expansion to a Sedov phase as it propagates into the main body of the ER, as also suggested by X-ray observations. The constant spectral shape of they IR, emission provides strong constraints on the density and temperature of the shocked gas in which the interaction takes place. The IR spectra also suggest the presence of a secondary population of very small, hot (T greater than or equal to 350 K), featureless dust. If these grains spatially coexists with the silicates, then they must have shorter lifetimes. The data show slightly different rates of increase of their respective fluxes, lending some support to this hypothesis. However, the origin of this emission component and the exact nature of its relation to the silicate emission is still a major unsolved puzzle.

  5. Gram-range explosive blast scaling and associated materials response

    E-print Network

    Settles, Gary S.

    Gram-range explosive blast scaling and associated materials response M. J. Hargather1 , G. S. Laboratory-scale gram-range explosive blast testing of materials is shown to be feasible. Blast loading from different explosive compounds is coupled to a witness plate through the air by way of a shock wave of known

  6. CAFE: A New Relativistic MHD Code

    NASA Astrophysics Data System (ADS)

    Lora-Clavijo, F. D.; Cruz-Osorio, A.; Guzmán, F. S.

    2015-06-01

    We introduce CAFE, a new independent code designed to solve the equations of relativistic ideal magnetohydrodynamics (RMHD) in three dimensions. We present the standard tests for an RMHD code and for the relativistic hydrodynamics regime because we have not reported them before. The tests include the one-dimensional Riemann problems related to blast waves, head-on collisions of streams, and states with transverse velocities, with and without magnetic field, which is aligned or transverse, constant or discontinuous across the initial discontinuity. Among the two-dimensional (2D) and 3D tests without magnetic field, we include the 2D Riemann problem, a one-dimensional shock tube along a diagonal, the high-speed Emery wind tunnel, the Kelvin–Helmholtz (KH) instability, a set of jets, and a 3D spherical blast wave, whereas in the presence of a magnetic field we show the magnetic rotor, the cylindrical explosion, a case of Kelvin–Helmholtz instability, and a 3D magnetic field advection loop. The code uses high-resolution shock-capturing methods, and we present the error analysis for a combination that uses the Harten, Lax, van Leer, and Einfeldt (HLLE) flux formula combined with a linear, piecewise parabolic method and fifth-order weighted essentially nonoscillatory reconstructors. We use the flux-constrained transport and the divergence cleaning methods to control the divergence-free magnetic field constraint.

  7. CAFE: A New Relativistic MHD Code

    E-print Network

    F. D. Lora-Clavijo; A. Cruz-Osorio; F. S. Guzman

    2015-05-12

    We introduce CAFE, a new independent code designed to solve the equations of Relativistic ideal Magnetohydrodynamics (RMHD) in 3D. We present the standard tests for a RMHD code and for the Relativistic Hydrodynamics (RHD) regime since we have not reported them before. The tests include the 1D Riemann problems related to blast waves, head-on collision of streams and states with transverse velocities, with and without magnetic field, which is aligned or transverse, constant or discontinuous across the initial discontinuity. Among the 2D and 3D tests, without magnetic field we include the 2D Riemann problem, a one dimensional shock tube along a diagonal, the high speed Emery wind tunnel, the Kelvin-Helmholtz instability, a set of jets and a 3D spherical blast wave, whereas in the presence of a magnetic field we show the magnetic rotor, the cylindrical explosion, a case of Kelvin-Helmholtz instability and a 3D magnetic field advection loop. The code uses High Resolution Shock Capturing methods and we present the error analysis for a combination that uses the HLLE flux formula combined with linear, PPM and fifth order WENO reconstructors. We use the flux-CT and the divergence cleaning methods to control the divergence free magnetic field constraint.

  8. Minimisation of the explosion shock wave load onto the occupants inside the vehicle during trinitrotoluene charge blast.

    PubMed

    Krzysta?a, Edyta; M??yk, Arkadiusz; Kciuk, S?awomir

    2014-10-13

    The aim of this study was to elaborate identification method of crew overload as a result of trinitrotoluene charge explosion under the military wheeled vehicle. During the study, an experimental military ground research was carried out. The aim of this research was to verify the mine blast resistance of the prototype wheeled vehicle according to STANG 4569 as well as the anti-explosive seat. Within the work, the original methodology was elaborated along with a prototype research statement. This article presents some results of the experimental research, thanks to which there is a possibility to estimate the crew's lives being endangered in an explosion through the measurement of acceleration as well as the pressure on the chest, head and internal organs. On the basis of our acceleration results, both effectiveness and infallibility of crew protective elements along with a blast mitigation seat were verified. PMID:25307173

  9. Use of a fast near-infrared spectrometer for absorption and emission measurements within the expanding blast wave of a high explosive

    NASA Astrophysics Data System (ADS)

    Koch, Jon; Piecuch, Scott; Lightstone, James; Carney, Joel

    2011-06-01

    We demonstrate the use of a fast InGaAs array and spectrometer to measure properties related to near-infrared absorption and emission (750 nm-1500 nm) following a high explosive detonation. Using a broadband light source and a rigid absorption gauge, gas temperatures are measured at a rate of 20 kHz for a period of several milliseconds behind the blast wave from a 20 g PETN detonation. The temperature and concentration of water vapor is determined by fitting experimental transmission spectra to a simulated database. Strong emission signatures obtained during the breakout event (integrated over approximately the first 20 microseconds) indicate the presence of high energy nitrogen atoms with temperatures as high as 9700 K. Measurements from water absorption at a distance of 23 cm from the charge indicate temperatures decaying from 1600 K to 600 K during the first few milliseconds. These measurements are intended to aid the development of detonation and explosive simulations. Supported by DTRA

  10. Model and numerical simulations of the propagation and absorption of a short laser pulse in a transparent dielectric material: Blast-wave launch and cavity formation

    SciTech Connect

    Hallo, Ludovic; Tikhonchuk, Vladimir T.; Mezel, Candice; Breil, Jerome [Universite Bordeaux 1, CNRS, CEA, UMR 5107, 33405 Talence Cedex (France); Bourgeade, Antoine [CEA-CESTA, BP 1, 33114 Le Barp (France)

    2007-07-01

    We present a theoretical model and its numerical realization, which describes a submicron cavity formation in a transparent dielectric under a tight focusing of a ultrashort laser pulse. The model contains two parts. The first one provides the laser energy deposition in the sample along with the energy balance--the reflection and transmission of the laser pulse. It resolves the full set of Maxwell's equations in the two-dimensional geometry coupled to the material equations describing the atomic ionization by the laser electric field and the secondary electron collisions and the recombination processes. The second part describes the launch of the blast wave and the cavity formation under the deposited laser energy. The results of numerical simulations are compared with a qualitative theoretical model and experimental results.

  11. Model and numerical simulations of the propagation and absorption of a short laser pulse in a transparent dielectric material: Blast-wave launch and cavity formation

    NASA Astrophysics Data System (ADS)

    Hallo, Ludovic; Bourgeade, Antoine; Tikhonchuk, Vladimir T.; Mezel, Candice; Breil, Jérome

    2007-07-01

    We present a theoretical model and its numerical realization, which describes a submicron cavity formation in a transparent dielectric under a tight focusing of a ultrashort laser pulse. The model contains two parts. The first one provides the laser energy deposition in the sample along with the energy balance—the reflection and transmission of the laser pulse. It resolves the full set of Maxwell’s equations in the two-dimensional geometry coupled to the material equations describing the atomic ionization by the laser electric field and the secondary electron collisions and the recombination processes. The second part describes the launch of the blast wave and the cavity formation under the deposited laser energy. The results of numerical simulations are compared with a qualitative theoretical model and experimental results.

  12. Particle Acceleration at Ultra-Relativistic Shocks and the Spectra of Relativistic Fireballs

    E-print Network

    Yves A. Gallant; Abraham Achterberg; John G. Kirk; Axel W. Guthmann

    2000-01-28

    We examine Fermi-type acceleration at relativistic shocks, and distinguish between the initial boost of the first shock crossing cycle, where the energy gain per particle can be very large, and the Fermi process proper with repeated shock crossings, in which the typical energy gain is of order unity. We calculate by means of numerical simulations the spectrum and angular distribution of particles accelerated by this Fermi process, in particular in the case where particle dynamics can be approximated as small-angle scattering. We show that synchrotron emission from electrons or positrons accelerated by this process can account remarkably well for the observed power-law spectra of GRB afterglows and Crab-like supernova remnants. In the context of a decelerating relativistic fireball, we calculate the maximum particle energy attainable by acceleration at the external blast wave, and discuss the minimum energy for this acceleration process and its consequences for the observed spectrum.

  13. Common analysis of the relativistic klystron and the standing-wave free-electron laser two-beam accelerator

    SciTech Connect

    Wurtele, J.S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Whittum, D.H. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Sessler, A.M. [Lawrence Berkeley Lab., CA (United States)

    1992-07-01

    This paper summarizes a new formalism which makes the analysis and understanding of both the relativistic klystron (RK) and the standing-wave free-electron laser (SWFEL) two-beam accelerator (TBA) available to a wide audience of accelerator physicists. A ``coupling impedance`` for both the RK and SWFEL is introduced, which can include realistic cavity features, such as beam and vacuum ports, in a simple manner. The RK and SWFEL macroparticle equations, which govern the energy and phase evolution of successive bunches in the beam, are of identical form, differing only by multiplicative factors. The analysis allows, for the first time, a relative comparison of the RF and SWFEL TBAs.

  14. Quasi-optical theory of relativistic surface-wave oscillators with one-dimensional and two-dimensional periodic planar structures

    SciTech Connect

    Ginzburg, N. S.; Zaslavsky, V. Yu. [Nizhny Novgorod State University, 23 Gagarin Ave., Nizhny Novgorod 603950 (Russian Federation) [Nizhny Novgorod State University, 23 Gagarin Ave., Nizhny Novgorod 603950 (Russian Federation); Institute of Applied Physics of Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Malkin, A. M.; Sergeev, A. S. [Institute of Applied Physics of Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation)] [Institute of Applied Physics of Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation)

    2013-11-15

    Within the framework of a quasi-optical approach, we develop 2D and 3D self-consistent theory of relativistic surface-wave oscillators. Presenting the radiation field as a sum of two counter-propagating wavebeams coupled on a shallow corrugated surface, we describe formation of an evanescent slow wave. Dispersion characteristics of the evanescent wave following from this method are in good compliance with those found from the direct cst simulations. Considering excitation of the slow wave by a sheet electron beam, we simulate linear and nonlinear stages of interaction, which allows us to determine oscillation threshold conditions, electron efficiency, and output coupling. The transition from the model of surface-wave oscillator operating in the ?-mode regime to the canonical model of relativistic backward wave oscillator is considered. We also described a modified scheme of planar relativistic surface-wave oscillators exploiting two-dimensional periodic gratings. Additional transverse propagating waves emerging on these gratings synchronize the emission from a wide sheet rectilinear electron beam allowing realization of a Cherenkov millimeter-wave oscillators with subgigawatt output power level.

  15. Blast-Driven Hydrodynamic Instability

    NASA Astrophysics Data System (ADS)

    Henry de Frahan, Marc T.; Johnsen, Eric

    2013-11-01

    Accurate characterization of mixing from hydrodynamic instabilities, such as Richtmyer-Meshkov, Rayleigh-Taylor, and Kelvin-Helmholtz, is important to many multi-fluid applications, particularly, inertial confinement fusion, supernova collapse, and scramjet combustion. We investigate the dynamics of a perturbed interface between two fluids subjected to a planar blast wave. An initial point source explosion initiates a blast, which can be described as a shock front followed by a rarefaction wave. The interface, therefore, experiences an instantaneous acceleration (a pressure increase) followed by a gradual, time-dependent deceleration (a pressure decrease). The resulting interaction gives rise to Richtmyer-Meshkov and Rayleigh-Taylor growth, depending on the shock strength and blast profile. Using a high-order accurate numerical method that prevents pressure errors at interfaces when simulating variable specific heats ratios, we identify regimes in which one or the other instability dominates. Accurate characterization of mixing from hydrodynamic instabilities, such as Richtmyer-Meshkov, Rayleigh-Taylor, and Kelvin-Helmholtz, is important to many multi-fluid applications, particularly, inertial confinement fusion, supernova collapse, and scramjet combustion. We investigate the dynamics of a perturbed interface between two fluids subjected to a planar blast wave. An initial point source explosion initiates a blast, which can be described as a shock front followed by a rarefaction wave. The interface, therefore, experiences an instantaneous acceleration (a pressure increase) followed by a gradual, time-dependent deceleration (a pressure decrease). The resulting interaction gives rise to Richtmyer-Meshkov and Rayleigh-Taylor growth, depending on the shock strength and blast profile. Using a high-order accurate numerical method that prevents pressure errors at interfaces when simulating variable specific heats ratios, we identify regimes in which one or the other instability dominates. This research was supported by the DOE NNSA/ASC under the predictive Science Academic Alliance Program by Grant No. DEFC52-08NA28616.

  16. Simulation of the energy distribution of relativistic electron precipitation caused by quasi-linear interactions with EMIC waves

    PubMed Central

    Li, Zan; Millan, Robyn M; Hudson, Mary K

    2013-01-01

    [1]Previous studies on electromagnetic ion cyclotron (EMIC) waves as a possible cause of relativistic electron precipitation (REP) mainly focus on the time evolution of the trapped electron flux. However, directly measured by balloons and many satellites is the precipitating flux as well as its dependence on both time and energy. Therefore, to better understand whether pitch angle scattering by EMIC waves is an important radiation belt electron loss mechanism and whether quasi-linear theory is a sufficient theoretical treatment, we simulate the quasi-linear wave-particle interactions for a range of parameters and generate energy spectra, laying the foundation for modeling specific events that can be compared with balloon and spacecraft observations. We show that the REP energy spectrum has a peaked structure, with a lower cutoff at the minimum resonant energy. The peak moves with time toward higher energies and the spectrum flattens. The precipitating flux, on the other hand, first rapidly increases and then gradually decreases. We also show that increasing wave frequency can lead to the occurrence of a second peak. In both single- and double-peak cases, increasing wave frequency, cold plasma density or decreasing background magnetic field strength lowers the energies of the peak(s) and causes the precipitation to increase at low energies and decrease at high energies at the start of the precipitation.

  17. Tunability over three frequency bands induced by mode transition in relativistic backward wave oscillator with strong end reflections

    SciTech Connect

    Wu, Ping; Deng, Yuqun [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Fan, Juping; Teng, Yan; Shi, Yanchao; Sun, Jun [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

    2014-10-15

    This paper presents an efficient approach to realizing the frequency tunability of a relativistic backward wave oscillator (RBWO) over three frequency bands by mode transition without changing the slow wave structure (SWS). It is figured out that the transition of the operation mode in the RBWO can be efficiently achieved by using the strong end reflection of the SWS. This mode transition results in the tunability of the RBWO over three frequency bands at high power and high efficiency without changing the SWS. In numerical simulation, the output frequency of the RBWO can jump over 7.9?GHz in C-band, 9.9?GHz in X-band, and 12.4?GHz in Ku-band with output power exceeding 3.0?GW and conversion efficiency higher than 35% by just reasonably transforming the structures of the front and post resonant reflectors which provide the strong end reflection for the SWS.

  18. Excitation of upper-hybrid waves by a gyrating relativistic electron beam in a magnetized dusty plasma cylinder

    SciTech Connect

    Sharma, Suresh C. [Department of Physics, Maharaja Agrasen Institute of Technology, PSP Area Plot No. 1, Sector 22, Rohini, Delhi 110086 (India); Gahlot, Ajay [Department of Physics, Maharaja Surajmal Institute of Technology, C-4 Janakpuri, Delhi 110058 (India)

    2009-12-15

    A gyrating relativistic electron beam propagating through a magnetized dusty plasma cylinder drives an upper-hybrid wave to instability via cyclotron interaction. Numerical calculations of the growth rate and unstable mode frequencies have been carried out for the typical parameters of dusty plasma experiments. It is found that as the density ratio of negatively charged dust grains to electrons increases, the unstable mode frequency of the upper-hybrid waves increases. Moreover, the growth rate of the instability also increases with the density ratio. The growth rate of the unstable mode has the largest value for the modes whose eigenfunctions peak at the location of the beam. The growth rate of the unstable mode scales as the one-third power of the beam density.

  19. Improved power capacity in a high efficiency klystron-like relativistic backward wave oscillator by distributed energy extraction

    NASA Astrophysics Data System (ADS)

    Xiao, Renzhen; Chen, Changhua; Cao, Yibing; Sun, Jun

    2013-12-01

    With the efficiency increase of a klystron-like relativistic backward wave oscillator, the maximum axial electric field and harmonic current simultaneously appear at the end of the beam-wave interaction region, leading to a highly centralized energy exchange in the dual-cavity extractor and a very high electric field on the cavity surface. Thus, we present a method of distributed energy extraction in this kind of devices. Particle-in-cell simulations show that with the microwave power of 5.1 GW and efficiency of 70%, the maximum axial electric field is decreased from 2.26 MV/cm to 1.28 MV/cm, indicating a threefold increase in the power capacity.

  20. Improved power capacity in a high efficiency klystron-like relativistic backward wave oscillator by distributed energy extraction

    SciTech Connect

    Xiao, Renzhen; Chen, Changhua; Cao, Yibing; Sun, Jun [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

    2013-12-07

    With the efficiency increase of a klystron-like relativistic backward wave oscillator, the maximum axial electric field and harmonic current simultaneously appear at the end of the beam-wave interaction region, leading to a highly centralized energy exchange in the dual-cavity extractor and a very high electric field on the cavity surface. Thus, we present a method of distributed energy extraction in this kind of devices. Particle-in-cell simulations show that with the microwave power of 5.1?GW and efficiency of 70%, the maximum axial electric field is decreased from 2.26 MV/cm to 1.28 MV/cm, indicating a threefold increase in the power capacity.

  1. Symmetry properties of the S matrix in a fully relativistic distorted-wave treatment of electron-impact ionization

    SciTech Connect

    Pyper, N. C.; Kampp, Marco; Whelan, Colm T. [University Chemical Laboratory, Lensfield Road, Cambridge, CB2 1EW (United Kingdom); Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW (United Kingdom); Department of Physics, Old Dominion University, Norfolk, Virginia 23529-0116 (United States)

    2005-05-15

    The symmetry properties of the S matrix in a fully relativistic distorted-wave treatment of electron-impact ionization are investigated. It is shown that the square modulus of the scattering matrix element in which the spin states of all four electrons are determined is not invariant under the reversal of the direction of alignment of all spins. The largest of two contributions to this noninvariance originates from the relativistic modifications of the continuum wave functions induced by the distorting potential of the target atom. A second smaller contribution is manifested on reducing the eight-dimensional matrix elements of the QED covariant propagator to purely spatial two-electron integrals. The triple differential cross section (TDCS) exhibits a spin asymmetry unless the entire scattering process occurs in a single plane. There will be a difference in the TDCS between an (e,2e) event in which the initial beam is polarized parallel or antiparallel with respect to the beam direction even if the target is unpolarized and the final spin states are not determined. The TDCS will remain unchanged if, in addition to reversal of the direction of spin alignment, one appropriate momentum component of one of the two outgoing electrons is reversed.

  2. June 7 Ballistic Blast Results in Solar Tsunami - Duration: 8 seconds.

    NASA Video Gallery

    In addition to the magnificent blast, SDO detected a shadowy shock wave issuing from the blast site on the June 7, 2011 event. The 'solar tsunami' propagated more than halfway across the sun, visib...

  3. Operation Greenhouse. Scientific Director's report of atomic-weapon tests at Eniwetok, 1951. Annex 4. 2. Measurement of surface-air movements associated with atomic blasts

    Microsoft Academic Search

    R. M. Rados; J. C. Bogert; T. O. Haig

    1985-01-01

    The purpose of this project was to record continuous measurements of the surface winds in the vicinity of an atomic blast immediately prior to the blast, during passage of the shock wave, and immediately after the blast with special regard to the blast-induced afterwind following local dissipation of the shock wave. From the data obtained, it was concluded that following

  4. Investigation of EMIC wave scattering as the cause for the BARREL 17 January 2013 relativistic electron precipitation event: A quantitative comparison of simulation with observations

    NASA Astrophysics Data System (ADS)

    Li, Zan; Millan, Robyn M.; Hudson, Mary K.; Woodger, Leslie A.; Smith, David M.; Chen, Yue; Friedel, Reiner; Rodriguez, Juan V.; Engebretson, Mark J.; Goldstein, Jerry; Fennell, Joseph F.; Spence, Harlan E.

    2014-12-01

    Electromagnetic ion cyclotron (EMIC) waves were observed at multiple observatory locations for several hours on 17 January 2013. During the wave activity period, a duskside relativistic electron precipitation (REP) event was observed by one of the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL) balloons and was magnetically mapped close to Geostationary Operational Environmental Satellite (GOES) 13. We simulate the relativistic electron pitch angle diffusion caused by gyroresonant interactions with EMIC waves using wave and particle data measured by multiple instruments on board GOES 13 and the Van Allen Probes. We show that the count rate, the energy distribution, and the time variation of the simulated precipitation all agree very well with the balloon observations, suggesting that EMIC wave scattering was likely the cause for the precipitation event. The event reported here is the first balloon REP event with closely conjugate EMIC wave observations, and our study employs the most detailed quantitative analysis on the link of EMIC waves with observed REP to date.

  5. Chronic Traumatic Encephalopathy in Blast-Exposed Military Veterans and a Blast Neurotrauma Mouse Model

    PubMed Central

    Goldstein, Lee E.; Fisher, Andrew M.; Tagge, Chad A.; Zhang, Xiao-Lei; Velisek, Libor; Sullivan, John A.; Upreti, Chirag; Kracht, Jonathan M.; Ericsson, Maria; Wojnarowicz, Mark W.; Goletiani, Cezar J.; Maglakelidze, Giorgi M.; Casey, Noel; Moncaster, Juliet A.; Minaeva, Olga; Moir, Robert D.; Nowinski, Christopher J.; Stern, Robert A.; Cantu, Robert C.; Geiling, James; Blusztajn, Jan K.; Wolozin, Benjamin L.; Ikezu, Tsuneya; Stein, Thor D.; Budson, Andrew E.; Kowall, Neil W.; Chargin, David; Sharon, Andre; Saman, Sudad; Hall, Garth F.; Moss, William C.; Cleveland, Robin O.; Tanzi, Rudolph E.; Stanton, Patric K.; McKee, Ann C.

    2013-01-01

    Blast exposure is associated with traumatic brain injury (TBI), neuropsychiatric symptoms, and long-term cognitive disability. We examined a case series of postmortem brains from U.S. military veterans exposed to blast and/or concussive injury. We found evidence of chronic traumatic encephalopathy (CTE), a tau protein–linked neurodegenerative disease, that was similar to the CTE neuropathology observed in young amateur American football players and a professional wrestler with histories of concussive injuries. We developed a blast neurotrauma mouse model that recapitulated CTE-linked neuropathology in wild-type C57BL/6 mice 2 weeks after exposure to a single blast. Blast-exposed mice demonstrated phosphorylated tauopathy, myelinated axonopathy, microvasculopathy, chronic neuroinflammation, and neurodegeneration in the absence of macroscopic tissue damage or hemorrhage. Blast exposure induced persistent hippocampal-dependent learning and memory deficits that persisted for at least 1 month and correlated with impaired axonal conduction and defective activity-dependent long-term potentiation of synaptic transmission. Intracerebral pressure recordings demonstrated that shock waves traversed the mouse brain with minimal change and without thoracic contributions. Kinematic analysis revealed blast-induced head oscillation at accelerations sufficient to cause brain injury. Head immobilization during blast exposure prevented blast-induced learning and memory deficits. The contribution of blast wind to injurious head acceleration may be a primary injury mechanism leading to blast-related TBI and CTE. These results identify common pathogenic determinants leading to CTE in blast-exposed military veterans and head-injured athletes and additionally provide mechanistic evidence linking blast exposure to persistent impairments in neurophysiological function, learning, and memory. PMID:22593173

  6. Configuration mixing of angular-momentum projected triaxial relativistic mean-field wave functions. II. Microscopic analysis of low-lying states in magnesium isotopes

    E-print Network

    J. M. Yao; H. Mei; H. Chen; J. Meng; P. Ring; D. Vretenar

    2010-06-08

    The recently developed structure model that uses the generator coordinate method to perform configuration mixing of angular-momentum projected wave functions, generated by constrained self-consistent relativistic mean-field calculations for triaxial shapes (3DAMP+GCM), is applied in a systematic study of ground states and low-energy collective states in the even-even magnesium isotopes $^{20-40}$Mg. Results obtained using a relativistic point-coupling nucleon-nucleon effective interaction in the particle-hole channel, and a density-independent $\\delta$-interaction in the pairing channel, are compared to data and with previous axial 1DAMP+GCM calculations, both with a relativistic density functional and the non-relativistic Gogny force. The effects of the inclusion of triaxial degrees of freedom on the low-energy spectra and E2 transitions of magnesium isotopes are examined.

  7. Generation of high-power nanosecond pulses in a relativistic backward-wave oscillator in the regime of spatial accumulation of energy

    Microsoft Academic Search

    K. V. Afanasyev; N. M. Bykov; V. P. Gubanov; A. A. Elchaninov; A. I. Klimov; S. D. Korovin; V. V. Rostov; A. S. Stepchenko

    2006-01-01

    We study the generation of electromagnetic pulses with a carrier frequency of 3.7 GHz in a relativistic backward-wave oscillator\\u000a with a long slow-wave system in the superradiance regime of super-radiation for a magnetic induction of 0.2 T (below the cyclotron\\u000a resonance). To decrease transverse velocities of the electrons, we use decompression of a hollow electron beam. Decompression\\u000a in combination with

  8. Concussive brain injury from explosive blast

    PubMed Central

    de Lanerolle, Nihal C; Hamid, Hamada; Kulas, Joseph; Pan, Jullie W; Czlapinski, Rebecca; Rinaldi, Anthony; Ling, Geoffrey; Bandak, Faris A; Hetherington, Hoby P

    2014-01-01

    Objective Explosive blast mild traumatic brain injury (mTBI) is associated with a variety of symptoms including memory impairment and posttraumatic stress disorder (PTSD). Explosive shock waves can cause hippocampal injury in a large animal model. We recently reported a method for detecting brain injury in soldiers with explosive blast mTBI using magnetic resonance spectroscopic imaging (MRSI). This method is applied in the study of veterans exposed to blast. Methods The hippocampus of 25 veterans with explosive blast mTBI, 20 controls, and 12 subjects with PTSD but without exposure to explosive blast were studied using MRSI at 7 Tesla. Psychiatric and cognitive assessments were administered to characterize the neuropsychiatric deficits and compare with findings from MRSI. Results Significant reductions in the ratio of N-acetyl aspartate to choline (NAA/Ch) and N-acetyl aspartate to creatine (NAA/Cr) (P < 0.05) were found in the anterior portions of the hippocampus with explosive blast mTBI in comparison to control subjects and were more pronounced in the right hippocampus, which was 15% smaller in volume (P < 0.05). Decreased NAA/Ch and NAA/Cr were not influenced by comorbidities – PTSD, depression, or anxiety. Subjects with PTSD without blast had lesser injury, which tended to be in the posterior hippocampus. Explosive blast mTBI subjects had a reduction in visual memory compared to PTSD without blast. Interpretation The region of the hippocampus injured differentiates explosive blast mTBI from PTSD. MRSI is quite sensitive in detecting and localizing regions of neuronal injury from explosive blast associated with memory impairment. PMID:25493283

  9. Bursts of Superreflected Laser Light from Inhomogeneous Plasmas due to the Generation of Relativistic Solitary Waves

    Microsoft Academic Search

    Y. Sentoku; T. Zh. Esirkepov; K. Mima; K. Nishihara; F. Califano; F. Pegoraro; H. Sakagami; Y. Kitagawa; N. M. Naumova; S. V. Bulanov

    1999-01-01

    In an inhomogeneous plasma, low-frequency solitary waves, generated by superintense laser pulses, are accelerated towards the plasma-vacuum interface where they radiate their energy in the form of low-frequency electromagnetic bursts. The transverse inhomogeneity of the plasma inside the self-focusing radiation channel leads to guiding of the solitary waves. These solitary waves excite a two-ribbon magnetic field structure in their wake.

  10. Use of a fast near-infrared spectrometer for absorption and emission measurements within the expanding blast wave of a high explosive

    NASA Astrophysics Data System (ADS)

    Koch, Jon D.; Carney, Joel; Lightstone, James; Piecuch, Scott

    2012-03-01

    We demonstrate the use of a fast InGaAs array and spectrometer to measure properties related to near-infrared absorption and emission (750 nm -1500 nm) following a high explosive detonation. Using a broadband light source and a rigid absorption gauge, gas temperatures are measured at a rate of 20 kHz for a period of several milliseconds behind the blast wave from a PETN, PBXN-5, and PBXN-113 detonations. The temperature and concentration of water vapor is determined by fitting experimental transmission spectra to a simulated database. Strong emission signatures obtained during the PETN breakout event (integrated over approximately the first 20 microseconds) indicate the presence of high energy nitrogen and oxygen atoms. Measurements from water absorption at a distance of 23 cm from the PETN charge indicate temperatures decaying from 1600 K to 600 K during the first few milliseconds, and measurements of non-ideal explosives with optically thick postdetonation environments are also demonstrated. These measurements are intended to aid the development of detonation and explosive simulations.

  11. Transition to turbulence and effect of initial conditions on three-dimensional compressible mixing in planar blast-wave-driven systems

    SciTech Connect

    Miles, A.R.; Blue, B.; Edwards, M.J.; Greenough, J.A.; Hansen, J.F.; Robey, H.F.; Drake, R.P.; Kuranz, C.; Leibrandt, D.R. [Lawrence Livermore National Laboratory, L-021, 7000 East Avenue, P.O. Box 808, Livermore, California 94551 (United States); University of Michigan, 2455 Hayward Street, Ann Arbor, Michigan 48109 (United States)

    2005-05-15

    Perturbations on an interface driven by a strong blast wave grow in time due to a combination of Rayleigh-Taylor, Richtmyer-Meshkov, and decompression effects. In this paper, results from three-dimensional (3D) numerical simulations of such a system under drive conditions to be attainable on the National Ignition Facility [E. M. Campbell, Laser Part. Beams 9, 209 (1991)] are presented. Using the multiphysics, adaptive mesh refinement, higher order Godunov Eulerian hydrocode, Raptor [L. H. Howell and J. A. Greenough, J. Comput. Phys. 184, 53 (2003)], the late nonlinear instability evolution, including transition to turbulence, is considered for various multimode perturbation spectra. The 3D post-transition state differs from the 2D result, but the process of transition proceeds similarly in both 2D and 3D. The turbulent mixing transition results in a reduction in the growth rate of the mixing layer relative to its pretransition value and, in the case of the bubble front, relative to the 2D result. The post-transition spike front velocity is approximately the same in 2D and 3D. Implications for hydrodynamic mixing in core-collapse supernovae are discussed.

  12. Traumatic brain injury caused by laser-induced shock wave in rats: a novel laboratory model for studying blast-induced traumatic brain injury

    NASA Astrophysics Data System (ADS)

    Hatano, Ben; Matsumoto, Yoshihisa; Otani, Naoki; Saitoh, Daizoh; Tokuno, Shinichi; Satoh, Yasushi; Nawashiro, Hiroshi; Matsushita, Yoshitaro; Sato, Shunichi

    2011-03-01

    The detailed mechanism of blast-induced traumatic brain injury (bTBI) has not been revealed yet. Thus, reliable laboratory animal models for bTBI are needed to investigate the possible diagnosis and treatment for bTBI. In this study, we used laser-induced shock wave (LISW) to induce TBI in rats and investigated the histopathological similarities to actual bTBI. After craniotomy, the rat brain was exposed to a single shot of LISW with a diameter of 3 mm at various laser fluences. At 24 h after LISW exposure, perfusion fixation was performed and the extracted brain was sectioned; the sections were stained with hematoxylin-eosin. Evans blue (EB) staining was also used to evaluate disruption of the blood brain barrier. At certain laser fluence levels, neural cell injury and hemorrhagic lesions were observed in the cortex and subcortical region. However, injury was limited in the tissue region that interacted with the LISW. The severity of injury increased with increasing laser fluence and hence peak pressure of the LISW. Fluorescence originating from EB was diffusively observed in the injuries at high fluence levels. Due to the grade and spatial controllability of injuries and the histological observations similar to those in actual bTBI, brain injuries caused by LISWs would be useful models to study bTBI.

  13. On Relativistic Quantum Information Properties of Entangled Wave Vectors of Massive Fermions

    Microsoft Academic Search

    C. Cafaro; S. Capozziello; S. Mancini

    2011-01-01

    We study special relativistic effects on the entanglement between either spins or momenta of composite quantum systems of two spin-1\\/2 massive particles, either indistinguishable or distinguishable, in inertial reference frames in relative motion. For the case of indistinguishable particles, we consider a balanced scenario where the momenta of the pair are well-defined but not maximally entangled in the rest frame

  14. Filamentation instability of ion acoustic waves driven by a scattered relativistic beam

    SciTech Connect

    Lee, H.; Jones, M.E.

    1983-01-01

    Ion-acoustic instability driven by a scattered relativistic beam propagating in a plasma of hot electrons and cold ions is investigated. We have derived a fully electromagnetic dispersion relation and its cold beam limit and discussed the general features of the growth rate spectrum. We find that this instability is sensitively damped by th beam temperature. Particle trapping and nonlinear growth are studied by using particle-in-cell simulations.

  15. Wave functions of mesons and the behavior of the meson form factors at small and intermediate Q² in the relativistic quark model

    Microsoft Academic Search

    A. S. Bagdasaryan; S. V. Esaibegyan; H. L. Ter-Isaakyan

    1985-01-01

    We have studied the structure of the wave function of the pion within the framework of the relativistic quark model and have found the form factors of the ..pi.., rho, and A⁠mesons and the transition form factors of the transitions ..omega --> pi gamma.. and Aâ..--> pi gamma... Our results for the ..pi.. and A⁠meson form factors and

  16. Computational modeling of human head under blast in confined and open spaces: primary blast injury.

    PubMed

    Rezaei, A; Salimi Jazi, M; Karami, G

    2014-01-01

    In this paper, a computational modeling for biomechanical analysis of primary blast injuries is presented. The responses of the brain in terms of mechanical parameters under different blast spaces including open, semi-confined, and confined environments are studied. In the study, the effect of direct and indirect blast waves from the neighboring walls in the confined environments will be taken into consideration. A 50th percentile finite element head model is exposed to blast waves of different intensities. In the open space, the head experiences a sudden intracranial pressure (ICP) change, which vanishes in a matter of a few milliseconds. The situation is similar in semi-confined space, but in the confined space, the reflections from the walls will create a number of subsequent peaks in ICP with a longer duration. The analysis procedure is based on a simultaneous interaction simulation of the deformable head and its components with the blast wave propagations. It is concluded that compared with the open and semi-confined space settings, the walls in the confined space scenario enhance the risk of primary blast injuries considerably because of indirect blast waves transferring a larger amount of damaging energy to the head. PMID:23996897

  17. Understanding the light curves of the HST-1 knot in M87 with internal relativistic shock waves along its jet

    E-print Network

    Coronado, Y; Mendoza, S

    2015-01-01

    Knots or blobs observed in astrophysical jets are commonly interpreted as shock waves moving along them. Long time observations of the HST-1 knot inside the jet of the galaxy M87 have produced detailed multi-wavelength light curves. In this article, we model these light curves using the semi-analytical approach developed by Mendoza et al. (2009). This model was developed to account for the light curves of working surfaces moving along relativistic jets. These working surfaces are generated by periodic oscillations of the injected flow velocity and mass ejection rates at the base of the jet. Using genetic algorithms to fit the parameters of the model, we are able to explain the outbursts observed in the light curves of the HST-1 knot with an accuracy greater than a 2 sigma statistical confidence level.

  18. The Relativistic Transformation for an Electromagnetic Plane Wave with General Time Dependence

    ERIC Educational Resources Information Center

    Smith, Glenn S.

    2012-01-01

    In special relativity, the transformation between inertial frames for an electromagnetic plane wave is usually derived for the time-harmonic case (the field is a sinusoid of infinite duration), even though all practical waves are of finite duration and may not even contain a dominant sinusoid. This paper presents an alternative derivation in which…

  19. Gun blast - Its propagation and determination

    NASA Astrophysics Data System (ADS)

    Schmidt, E. M.; Kahl, G. D.; Shear, D. D.

    1980-06-01

    Muzzle blast overpressure levels are limiting the operation of high performance gun systems. The pressures at crew stations are of particular concern and have not been well defined either experimentally or analytically. The present paper presents measurement and analysis of the blast fields about a range of weapons from small arms through artillery. The effects of near muzzle flow upon the blast wave are discussed and a scaling relationship is developed from experimental data which is extended to various weapons and shown to predict pressure acceptably.

  20. Dispersion relation and growth rate of a relativistic electron beam propagating through a Langmuir wave wiggler

    NASA Astrophysics Data System (ADS)

    Zirak, H.; Jafari, S.

    2015-06-01

    In this study, a theory of free-electron laser (FEL) with a Langmuir wave wiggler in the presence of an axial magnetic field has been presented. The small wavelength of the plasma wave (in the sub-mm range) allows obtaining higher frequency than conventional wiggler FELs. Electron trajectories have been obtained by solving the equations of motion for a single electron. In addition, a fourth-order Runge-Kutta method has been used to simulate the electron trajectories. Employing a perturbation analysis, the dispersion relation for an electromagnetic and space-charge waves has been derived by solving the momentum transfer, continuity, and wave equations. Numerical calculations show that the growth rate increases with increasing the e-beam energy and e-beam density, while it decreases with increasing the strength of the axial guide magnetic field.

  1. ULF wave indices to characterize the solar wind-magnetosphere interaction and relativistic electron dynamics

    Microsoft Academic Search

    Natalia Romanova; Viacheslav Pilipenko

    2009-01-01

    To quantify the level of low-frequency wave activity of the magnetosphere and IMF, a set of the ULF wave power indices has\\u000a been introduced. We demonstrate that the ULF activity global level can be very useful in space weather related problems. The\\u000a application of the interplanetary index to an analysis of auroral activity driving has shown that a turbulent IMF

  2. Optimization of the regime of shortening of relativistically strong laser pulses in the process of excitation of a plasma wake wave

    NASA Astrophysics Data System (ADS)

    Kim, A. V.; Litvak, A. G.; Mironov, V. A.; Skobelev, S. A.

    2014-10-01

    A detailed theoretical investigation is performed for the self-compression of relativistically strong laser pulses under plasma wake wave excitation conditions. An analytical expression is obtained for the characteristic length of laser pulse self-compression in the one-dimensional case. A good agreement between the theoretical and numerical calculation of the dependence of the wave-packet compression length on both amplitude and plasma concentration is demonstrated. The influence of the wave beam self-focusing radiation process on the rate of shortening of the laser pulse duration is considered.

  3. About excitation of surface plasma waves by elliptical relativistic electron beam in a magnetized dusty plasma column with elliptical cross section

    SciTech Connect

    Abdoli-Arani, A.; Jazi, B. [Department of Physics, University of Kashan, Kashan (Iran, Islamic Republic of)

    2012-05-15

    The surface plasma waves in a magnetized dusty plasma elliptical cylinder driven by elliptic relativistic electron beam propagating inside the elliptical cylinder are studied. The dispersion relation of surface plasma waves has been retrieved from the derived dispersion relation by considering that the beam is absent and there is no dust in the plasma cylinder. Mathematically, it is shown that the beam can interact with the surface plasma waves via Cerenkov interaction and fast cyclotron interaction. The growth rate and phase velocity in every cases are obtained. Finally, the numerical results and graphs are presented.

  4. Relativistic breather-type solitary waves with linear polarization in cold plasmas

    NASA Astrophysics Data System (ADS)

    Sánchez-Arriaga, G.; Siminos, E.; Saxena, V.; Kourakis, I.

    2015-03-01

    Linearly polarized solitary waves, arising from the interaction of an intense laser pulse with a plasma, are investigated. Localized structures, in the form of exact numerical nonlinear solutions of the one-dimensional Maxwell-fluid model for a cold plasma with fixed ions, are presented. Unlike stationary circularly polarized solitary waves, the linear polarization gives rise to a breather-type behavior and a periodic exchange of electromagnetic energy and electron kinetic energy at twice the frequency of the wave. A numerical method based on a finite-differences scheme allows us to compute a branch of solutions within the frequency range ?minwaves and their main properties as a function of ? is presented. Small-amplitude oscillations appearing in the tail of the solitary waves, a consequence of the linear polarization and harmonic excitation, are explained with the aid of the Akhiezer-Polovin system. Direct numerical simulations of the Maxwell-fluid model show that these solitary waves propagate without change for a long time.

  5. Two-dimensional s-polarized solitary waves in relativistic plasmas. I. The fluid plasma model

    SciTech Connect

    Sanchez-Arriaga, G.; Lefebvre, E. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2011-09-15

    The properties of two-dimensional linearly s-polarized solitary waves are investigated by fluid-Maxwell equations and particle-in-cell (PIC) simulations. These self-trapped electromagnetic waves appear during laser-plasma interactions, and they have a dominant electric field component E{sub z}, normal to the plane of the wave, that oscillates at a frequency below the electron plasma frequency {omega}{sub pe}. A set of equations that describe the waves are derived from the plasma fluid model in the case of cold or warm plasma and then solved numerically. The main features, including the maximum value of the vector potential amplitude, the total energy, the width, and the cavitation radius are presented as a function of the frequency. The amplitude of the vector potential increases monotonically as the frequency of the wave decreases, whereas the width reaches a minimum value at a frequency of the order of 0.82 {omega}{sub pe}. The results are compared with a set of PIC simulations where the solitary waves are excited by a high-intensity laser pulse.

  6. Relativistic breather-type solitary waves with linear polarization in cold plasmas.

    PubMed

    Sánchez-Arriaga, G; Siminos, E; Saxena, V; Kourakis, I

    2015-03-01

    Linearly polarized solitary waves, arising from the interaction of an intense laser pulse with a plasma, are investigated. Localized structures, in the form of exact numerical nonlinear solutions of the one-dimensional Maxwell-fluid model for a cold plasma with fixed ions, are presented. Unlike stationary circularly polarized solitary waves, the linear polarization gives rise to a breather-type behavior and a periodic exchange of electromagnetic energy and electron kinetic energy at twice the frequency of the wave. A numerical method based on a finite-differences scheme allows us to compute a branch of solutions within the frequency range ?_{min}waves and their main properties as a function of ? is presented. Small-amplitude oscillations appearing in the tail of the solitary waves, a consequence of the linear polarization and harmonic excitation, are explained with the aid of the Akhiezer-Polovin system. Direct numerical simulations of the Maxwell-fluid model show that these solitary waves propagate without change for a long time. PMID:25871219

  7. Characteristics of pressure waves

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Air blast characteristics generated by most types of explosions are discussed. Data cover both negative and positive blast load phases and net transverse pressure as a function of time. The effects of partial or total confinement, atmospheric propagation, absorption of energy by ground shock or cratering, and transmission over irregular terrain on blast wave properties were also considered.

  8. Plasma expansion and impedance collapse in a foil-less diode for a klystronlike relativistic backward wave oscillator

    SciTech Connect

    Xiao Renzhen; Sun Jun; Huo Shaofei; Li Xiaoze; Zhang Ligang; Zhang Xiaowei; Zhang Lijun [Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

    2010-12-15

    Klystronlike relativistic backward wave oscillator (RBWO) can produce microwave power exceeding 5 GW with a high efficiency larger than 40%. In the experiment of klystronlike RBWO, for about 1 MV peak diode voltages, increasing magnetic field from 1.43 to 1.89 T slowed the impedance collapse until it was suppressed completely. The introduction of a stainless steel obstructing ring aggravated the impedance collapse, whereas replacing the stainless steel obstructing ring with a flat stainless steel provided a more stable impedance variation during the pulse duration. These impedance collapses did not affect microwave generation seriously and may be attributed to the radial expansion of cathode plasma initialing from the cathode shank so that part of reverse currents were collected at the anode wall, contributing to the measured diode current. On the other hand, it was found that microwave generation shot-to-shot reproducibility was closely related to the diode impedance variation. When there was no or very low microwave measured, diode impedance collapse appeared at the latter of the pulse. The microwave generation shot-to-shot reproducibility was improved greatly after the electron collector was enlarged on radius with 1 mm. A possible explanation is that the anode plasma produced from electron collector expands axially and enters the diode region at a very high velocity of several mm/ns. The movement of the anode plasma in the beam-wave interaction region affects the microwave generation, which reduces the microwave power during the whole pulse duration significantly.

  9. Turbulence induced additional deceleration in relativistic shock wave propagation: implications for gamma-ray burst

    NASA Astrophysics Data System (ADS)

    Liu, Xue-Wen

    2012-11-01

    The late afterglow of gamma-ray burst is believed to be due to progressive deceleration of the forward shock wave driven by the gamma-ray burst ejecta propagating in the interstellar medium. We study the dynamic effect of interstellar turbulence on shock wave propagation. It is shown that the shock wave decelerates more quickly than previously assumed without the turbulence. As an observational consequence, an earlier jet break will appear in the light curve of the forward shock wave. The scatter of the jet-corrected energy release for gamma-ray burst, inferred from the jet-break, may be partly due to the physical uncertainties in the turbulence/shock wave interaction. This uncertainties also exist in two shell collisions in the well-known internal shock model proposed for gamma-ray burst prompt emission. The large scatters of known luminosity relations of gamma-ray burst may be intrinsic and thus gamma-ray burst is not a good standard candle. We also discuss the other implications.

  10. Gravitational waves from stochastic relativistic sources: primordial turbulence and magnetic fields

    E-print Network

    Chiara Caprini; Ruth Durrer

    2006-09-15

    The power spectrum of a homogeneous and isotropic stochastic variable, characterized by a finite correlation length, does in general not vanish on scales larger than the correlation scale. If the variable is a divergence free vector field, we demonstrate that its power spectrum is blue on large scales. Accounting for this fact, we compute the gravitational waves induced by an incompressible turbulent fluid and by a causal magnetic field present in the early universe. The gravitational wave power spectra show common features: they are both blue on large scales, and peak at the correlation scale. However, the magnetic field can be treated as a coherent source and it is active for a long time. This results in a very effective conversion of magnetic energy in gravitational wave energy at horizon crossing. Turbulence instead acts as a source for gravitational waves over a time interval much shorter than a Hubble time, and the conversion into gravitational wave energy is much less effective. We also derive a strong constraint on the amplitude of a primordial magnetic field when the correlation length is much smaller than the horizon.

  11. Pitch angle scattering of relativistic electrons from stationary magnetic waves: Continuous Markov process and quasilinear theory

    SciTech Connect

    Lemons, Don S. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2012-01-15

    We develop a Markov process theory of charged particle scattering from stationary, transverse, magnetic waves. We examine approximations that lead to quasilinear theory, in particular the resonant diffusion approximation. We find that, when appropriate, the resonant diffusion approximation simplifies the result of the weak turbulence approximation without significant further restricting the regime of applicability. We also explore a theory generated by expanding drift and diffusion rates in terms of a presumed small correlation time. This small correlation time expansion leads to results valid for relatively small pitch angle and large wave energy density - a regime that may govern pitch angle scattering of high-energy electrons into the geomagnetic loss cone.

  12. Nonlinear Korteweg-de Vries-Burger equation for ion acoustic shock waves in a weakly relativistic electron-positron-ion plasma with thermal ions

    SciTech Connect

    Saeed, R.; Shah, Asif [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad 44000 (Pakistan)

    2010-03-15

    The nonlinear propagation of ion acoustic waves in electron-positron-ion plasma comprising of Boltzmannian electrons, positrons, and relativistic thermal ions has been examined. The Korteweg-de Vries-Burger equation has been derived by reductive perturbation technique, and its shock like solution is determined analytically through tangent hyperbolic method. The effect of various plasma parameters on strength and structure of shock wave is investigated. The pert graphical view of the results has been presented for illustration. It is observed that strength and steepness of the shock wave enervate with an increase in the ion temperature, relativistic streaming factor, positron concentrations, electron temperature and they accrue with an increase in coefficient of kinematic viscosity. The convective, dispersive, and dissipative properties of the plasma are also discussed. It is determined that the electron temperature has remarkable influence on the propagation and structure of nonlinear wave in such relativistic plasmas. The numerical analysis has been done based on the typical numerical data from a pulsar magnetosphere.

  13. The New BLAST Results Page

    E-print Network

    Levin, Judith G.

    The New BLAST® Results Page Enhanced graphical presentation and added functionality http://blast.ncbi.nlm.nih.gov, 2013 Contact: blast-help@ncbi.nlm.nih.gov Scope NCBI has introduced an enhanced report for search BLAST result page Access to NCBI BLAST web services through its homepage (blast.ncbi.nlm.nih.gov

  14. The 'Regularity Singularity' at Points of General Relativistic Shock Wave Interaction

    E-print Network

    Moritz Reintjes

    2014-09-18

    A proof that a new kind of non-removable {\\it "regularity singularity"} forms when two shock waves collide within the theory of General Relativity, was first announced in ProcRoySoc A \\cite{ReintjesTemple}. In the present paper we give complete proofs of the claims in \\cite{ReintjesTemple} and extend the results on the regularity of the Einstein curvature tensor to the full Riemann curvature tensor. The main result is that, in a neighborhood of a point where two shock waves collide in a spherically symmetric spacetime, the gravitational metric tensor cannot be lifted from C0,1 to C1 within the class of C1,1 coordinate transformations. This contrasts Israel's celebrated theorem \\cite{Israel}, which states that around each point on a {\\it single} shock surface there exist a coordinate system in which the metric is C1,1 regular. Moreover, at points of shock wave interaction, delta function sources exist in the second derivatives of the gravitational metric tensor in all coordinate systems of the C1,1-atlas, but due to cancellation, the Einstein and Riemann curvature tensor remain sup-norm bounded. We conclude that points of shock wave interaction are a new kind of spacetime singularity, (which we name "regularity singularity"), singularities that can form from the evolution of smooth initial data for perfect fluids and that lie in physical spacetime, but at such points {\\it locally inertial} coordinates fail to exist.

  15. Relativistic particle acceleration in the process of whistler-mode chorus wave generation

    Microsoft Academic Search

    Yuto Katoh; Yoshiharu Omura

    2007-01-01

    We have found that efficient acceleration of resonant electrons takes place in a self-consistent particle simulation reproducing whistler-mode chorus emissions. While the majority of electrons lose energy contributing to the generation of chorus emissions, a fraction of resonant electrons having large pitch angle are simultaneously energized through nonlinear wave trapping by the generated chorus emissions. A small fraction of energetic

  16. General relativistic shock-waves propagating at the speed of light

    Microsoft Academic Search

    Michael Brian Scott

    2002-01-01

    We investigate shock-wave solutions of the Einstein equations in the case when the speed of propagation is equal to the speed of light. The work extends the shock matching theory of Smoller and Temple to the lightlike case. After a brief introduction to general relativity, we introduce a previously known generalization of the second fundamental form by Barrabes and Israel.

  17. Relativistic scattered-wave theory. II - Normalization and symmetrization. [of Dirac wavefunctions

    NASA Technical Reports Server (NTRS)

    Yang, C. Y.

    1978-01-01

    Formalisms for normalization and symmetrization of one-electron Dirac scattered-wave wavefunctions are presented. The normalization integral consists of one-dimensional radial integrals for the spherical regions and an analytic expression for the intersphere region. Symmetrization drastically reduces the size of the secular matrix to be solved. Examples for planar Pb2Se2 and tetrahedral Pd4 are discussed.

  18. ARL Explosive Blast Bar Gauge Response Simulation

    NASA Astrophysics Data System (ADS)

    Sutherland, Gerrit; Boyle, Vincent; Benjamin, Richard

    2013-06-01

    Simulations allow us to optimize the design of a bar gauge. The incident blast wave imparts a wave that travels down the metal bar. Strain gauges positioned along the bar measure the strain produced by the bar wave, allowing determination of pressure and impulse at the bar face. The measured pressure history depends on the arrangement of the bar gauge. If a large metal plate surrounds the bar face, a reflected blast pressure is measured. If a metal fixture that forms a nozzle surrounds the bar face, the initial pressure will be the same as above. In time, release waves emanating from the nozzle edge will decrease the pressure at the bar face. The bar diameter and size of strain gauges control the time response or gauge bandwidth. CTH hydrocode simulations allow optimization of bar gauge features for various size explosive charges. The simulations predicted the response of the metal plate arrangement to a blast from a spherical composition C4 charge. The simulations predicted the proper metal plate diameter for a reflected pressure measurement. Other simulations compared the response of the bar gauge for both configurations (nozzle or plate surround) when subjected to the same blast loading. Pressure histories from simulations were compared to those from experiment and those predicted by the CONWEP blast code. The initial experimental and CONWEP pressures were in reasonable agreement.

  19. Modelling human eye under blast loading.

    PubMed

    Esposito, L; Clemente, C; Bonora, N; Rossi, T

    2015-01-01

    Primary blast injury (PBI) is the general term that refers to injuries resulting from the mere interaction of a blast wave with the body. Although few instances of primary ocular blast injury, without a concomitant secondary blast injury from debris, are documented, some experimental studies demonstrate its occurrence. In order to investigate PBI to the eye, a finite element model of the human eye using simple constitutive models was developed. The material parameters were calibrated by a multi-objective optimisation performed on available eye impact test data. The behaviour of the human eye and the dynamics of mechanisms occurring under PBI loading conditions were modelled. For the generation of the blast waves, different combinations of explosive (trinitrotoluene) mass charge and distance from the eye were analysed. An interpretation of the resulting pressure, based on the propagation and reflection of the waves inside the eye bulb and orbit, is proposed. The peculiar geometry of the bony orbit (similar to a frustum cone) can induce a resonance cavity effect and generate a pressure standing wave potentially hurtful for eye tissues. PMID:23521031

  20. Relativistic Electron Beam Acceleration by Compton Scattering of Lower-Hybrid Waves

    E-print Network

    Boyer, Edmond

    ,2 | |U E= k k k ( )1 8 = k k k k , 2 db b b eU n m c= bg p , ,db bn g= P p p b 0 , , 4 A A = - k k k k k k 1 0A A = k k , ( )( ) ( ) , , , , , ,Im b b A C D = +k k k k k k k k k . Here, U. The matrix elements ( ) , , b C k k k and giving the nonlinear wave-particle coupling coefficients and are

  1. General Relativistic Shock-Waves Propagating at the Speed of Light

    Microsoft Academic Search

    Michael Brian Scott

    2002-01-01

    We investigate shock-wave solutions of the Einstein equations in the case\\u000awhen the speed of propagation is equal to the speed of light. The work extends\\u000athe shock matching theory of Smoller and Temple, which characterizes solutions\\u000aof the Einstein equations when the spacetime metric is only Lipschitz\\u000acontinuous across a hypersurface, to the lightlike case. After a brief\\u000aintroduction

  2. On Relativistic Quantum Information Properties of Entangled Wave Vectors of Massive Fermions

    E-print Network

    Cafaro, C; Mancini, S

    2011-01-01

    We study special relativistic effects on the entanglement between either spins or momenta of composite quantum systems of two spin-1/2 massive particles, either indistinguishable or distinguishable, in inertial reference frames in relative motion. For the case of indistinguishable particles, we consider a balanced scenario where the momenta of the pair are well-defined but not maximally entangled in the rest frame while the spins of the pair are described by a one-parameter ($\\eta$) family of entangled bipartite states. For the case of distinguishable particles, we consider an unbalanced scenario where the momenta of the pair are well-defined and maximally entangled in the rest frame while the spins of the pair are described by a one-parameter ($\\xi$) family of non-maximally entangled bipartite states. In both cases, we show that neither the spin-spin ($ss$) nor the momentum-momentum ($mm$) entanglements quantified by means of Wootters' concurrence are Lorentz invariant quantities: the total amount of entangl...

  3. Structural blast design

    E-print Network

    Kieval, Tamar S. (Tamar Shoshana), 1980-

    2004-01-01

    Blast design is a necessary part of design for more buildings in the United States. Blast design is no longer limited to underground shelters and sensitive military sites, buildings used by the general public daily must ...

  4. Relativistic distorted-wave collision strengths for the 16 ?n = 0 optically allowed transitions with n = 2 in the 67 O-like ions with 26 ? Z ? 92

    NASA Astrophysics Data System (ADS)

    Fontes, Christopher J.; Zhang, Hong Lin

    2015-01-01

    Relativistic distorted-wave collision strengths have been calculated for the 16 ?n = 0 optically allowed transitions with n = 2 in the 67 O-like ions with nuclear charge number Z in the range 26 ? Z ? 92. The calculations were made for the four final, or scattered, electron energies E? = 0.20 , 0.42 , 0.80, and 1.40, where E? is in units of Zeff2 Ry with Zeff = Z - 5.83. In the present calculations, an improved "top-up" method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb-Bethe approximation used in previous work by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 82 (2002) 357]. In that earlier work, collision strengths were also provided for O-like ions, but for a more comprehensive data set consisting of all possible 45 ?n = 0 transitions, six scattered energies, and the 79 ions with Z in the range 14 ? Z ? 92. The collision strengths covered in the present work should be more accurate than the corresponding data given by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 82 (2002) 357] and are presented here to replace those earlier results.

  5. On Relativistic Quantum Information Properties of Entangled Wave Vectors of Massive Fermions

    E-print Network

    C. Cafaro; S. Capozziello; S. Mancini

    2011-11-09

    We study special relativistic effects on the entanglement between either spins or momenta of composite quantum systems of two spin-1/2 massive particles, either indistinguishable or distinguishable, in inertial reference frames in relative motion. For the case of indistinguishable particles, we consider a balanced scenario where the momenta of the pair are well-defined but not maximally entangled in the rest frame while the spins of the pair are described by a one-parameter ($\\eta$) family of entangled bipartite states. For the case of distinguishable particles, we consider an unbalanced scenario where the momenta of the pair are well-defined and maximally entangled in the rest frame while the spins of the pair are described by a one-parameter ($\\xi$) family of non-maximally entangled bipartite states. In both cases, we show that neither the spin-spin ($ss$) nor the momentum-momentum ($mm$) entanglements quantified by means of Wootters' concurrence are Lorentz invariant quantities: the total amount of entanglement regarded as the sum of these entanglements is not the same in different inertial moving frames. In particular, for any value of the entangling parameters, both $ss$ and $mm$-entanglements are attenuated by Lorentz transformations and their parametric rates of change with respect to the entanglements observed in a rest frame have the same monotonic behavior. However, for indistinguishable (distinguishable) particles, the change in entanglement for the momenta is (is not) the same as the change in entanglement for spins. As a consequence, in both cases, no entanglement compensation between spin and momentum degrees of freedom occurs.

  6. On Relativistic Quantum Information Properties of Entangled Wave Vectors of Massive Fermions

    NASA Astrophysics Data System (ADS)

    Cafaro, Carlo; Capozziello, Salvatore; Mancini, Stefano

    2012-08-01

    We study special relativistic effects on the entanglement between either spins or momenta of composite quantum systems of two spin-1/2 massive particles, either indistinguishable or distinguishable, in inertial reference frames in relative motion. For the case of indistinguishable particles, we consider a balanced scenario where the momenta of the pair are well-defined but not maximally entangled in the rest frame while the spins of the pair are described by a one-parameter ( ?) family of entangled bipartite states. For the case of distinguishable particles, we consider an unbalanced scenario where the momenta of the pair are well-defined and maximally entangled in the rest frame while the spins of the pair are described by a one-parameter ( ?) family of non-maximally entangled bipartite states. In both cases, we show that neither the spin-spin ( ss) nor the momentum-momentum ( mm) entanglements quantified by means of Wootters' concurrence are Lorentz invariant quantities: the total amount of entanglement regarded as the sum of these entanglements is not the same in different inertial moving frames. In particular, for any value of the entangling parameters, both ss and mm-entanglements are attenuated by Lorentz transformations and their parametric rates of change with respect to the entanglements observed in a rest frame have the same monotonic behavior. However, for indistinguishable (distinguishable) particles, the change in entanglement for the momenta is (is not) the same as the change in entanglement for spins. As a consequence, in both cases, no entanglement compensation between spin and momentum degrees of freedom occurs.

  7. Plasma relativistic microwave electronics

    Microsoft Academic Search

    M. V. Kuzelev; O. T. Loza; A. A. Rukhadze; P. S. Strelkov; A. G. Shkvarunets

    2001-01-01

    The principles of plasma relativistic microwave electronics based on the stimulated Cherenkov emission of electromagnetic\\u000a waves during the interaction of a relativistic electron beam with a plasma are formulated. A theory of relativistic Cherenkov\\u000a plasma microwave oscillators and amplifiers is developed, and model experimental devices are elaborated and investigated.\\u000a The emission mechanisms are studied theoretically. The efficiencies and frequency spectra

  8. Experimental Studies of Mitigation Materials for Blast Induced Tbi

    NASA Astrophysics Data System (ADS)

    Alley, M. D.; Son, S. F.; Christou, G.; Goel, R.; Young, L.

    2009-12-01

    The objective of this experimental study is to compare the effects of various materials obstructing the flow of a blast wave and the ability of the material to reduce the damage caused by the blast. Several methods of energy transfer in blast wave flows are expected including: material interfaces with impedance mismatches, density changes in a given material, internal shearing, and particle fracture. Our hypothesis is that the greatest energy transfer within the obstructing material will yield the greatest mitigation effects to the blast. Sample configurations of foam were varied to introduce material interfaces and filler materials with varying densities and impedances (liquids and powders). The samples were dynamically loaded using a small scale blast produced by an explosive driven shock tube housing gram-scale explosive charges. The transmitted blast profiles were analyzed for variations in impulse characteristics and frequency components as compared to standard free field profiles. The results showed a rounding effect of the transmitted blast profile for all samples with the effects of the high density fillers surpassing all others tested. These results lead to a conclusion that low porosity, high density materials offer superior attenuation by reducing air blast features and spatially distributing the transmitted wave.

  9. A general solution to non-linear particle acceleration at non-relativistic shock waves

    E-print Network

    Elena Amato; Pasquale Blasi

    2005-09-22

    Diffusive acceleration at collisionless shock waves remains one of the most promising acceleration mechanisms for the description of the origin of cosmic rays at all energies. A crucial ingredient to be taken into account is the reaction of accelerated particles on the shock, which in turn determines the efficiency of the process. Here we propose a semi-analytical kinetic method that allows us to calculate the shock modification induced by accelerated particles together with the efficiency for particle acceleration and the spectra of accelerated particles. The shock modification is calculated for arbitrary environment parameters (Mach number, maximum momentum, density) and for arbitrary diffusion properties of the medium. Several dependences of the diffusion coefficient on particle momentum and location are considered to assess the goodness of the method.

  10. MONTE CARLO SIMULATIONS OF NONLINEAR PARTICLE ACCELERATION IN PARALLEL TRANS-RELATIVISTIC SHOCKS

    SciTech Connect

    Ellison, Donald C.; Warren, Donald C. [Physics Department, North Carolina State University, Box 8202, Raleigh, NC 27695 (United States); Bykov, Andrei M., E-mail: don_ellison@ncsu.edu, E-mail: ambykov@yahoo.com [Ioffe Institute for Physics and Technology, 194021 St. Petersburg (Russian Federation)

    2013-10-10

    We present results from a Monte Carlo simulation of a parallel collisionless shock undergoing particle acceleration. Our simulation, which contains parameterized scattering and a particular thermal leakage injection model, calculates the feedback between accelerated particles ahead of the shock, which influence the shock precursor and 'smooth' the shock, and thermal particle injection. We show that there is a transition between nonrelativistic shocks, where the acceleration efficiency can be extremely high and the nonlinear compression ratio can be substantially greater than the Rankine-Hugoniot value, and fully relativistic shocks, where diffusive shock acceleration is less efficient and the compression ratio remains at the Rankine-Hugoniot value. This transition occurs in the trans-relativistic regime and, for the particular parameters we use, occurs around a shock Lorentz factor ?{sub 0} = 1.5. We also find that nonlinear shock smoothing dramatically reduces the acceleration efficiency presumed to occur with large-angle scattering in ultra-relativistic shocks. Our ability to seamlessly treat the transition from ultra-relativistic to trans-relativistic to nonrelativistic shocks may be important for evolving relativistic systems, such as gamma-ray bursts and Type Ibc supernovae. We expect a substantial evolution of shock accelerated spectra during this transition from soft early on to much harder when the blast-wave shock becomes nonrelativistic.

  11. A Multi-Mode Shock Tube for Investigation of Blast-Induced Traumatic Brain Injury

    PubMed Central

    Reneer, Dexter V.; Hisel, Richard D.; Hoffman, Joshua M.; Kryscio, Richard J.; Lusk, Braden T.

    2011-01-01

    Abstract Blast-induced mild traumatic brain injury (bTBI) has become increasingly common in recent military conflicts. The mechanisms by which non-impact blast exposure results in bTBI are incompletely understood. Current small animal bTBI models predominantly utilize compressed air-driven membrane rupture as their blast wave source, while large animal models use chemical explosives. The pressure-time signature of each blast mode is unique, making it difficult to evaluate the contributions of the different components of the blast wave to bTBI when using a single blast source. We utilized a multi-mode shock tube, the McMillan blast device, capable of utilizing compressed air- and compressed helium-driven membrane rupture, and the explosives oxyhydrogen and cyclotrimethylenetrinitramine (RDX, the primary component of C-4 plastic explosives) as the driving source. At similar maximal blast overpressures, the positive pressure phase of compressed air-driven blasts was longer, and the positive impulse was greater, than those observed for shockwaves produced by other driving sources. Helium-driven shockwaves more closely resembled RDX blasts, but by displacing air created a hypoxic environment within the shock tube. Pressure-time traces from oxyhydrogen-driven shockwaves were very similar those produced by RDX, although they resulted in elevated carbon monoxide levels due to combustion of the polyethylene bag used to contain the gases within the shock tube prior to detonation. Rats exposed to compressed air-driven blasts had more pronounced vascular damage than those exposed to oxyhydrogen-driven blasts of the same peak overpressure, indicating that differences in blast wave characteristics other than peak overpressure may influence the extent of bTBI. Use of this multi-mode shock tube in small animal models will enable comparison of the extent of brain injury with the pressure-time signature produced using each blast mode, facilitating evaluation of the blast wave components contributing to bTBI. PMID:21083431

  12. Investigation of shock waves in the relativistic Riemann problem: A comparison of viscous fluid dynamics to kinetic theory

    SciTech Connect

    Bouras, I.; El, A.; Fochler, O.; Greiner, C. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main (Germany); Molnar, E. [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany); KFKI, Research Institute of Particle and Nuclear Physics, H-1525 Budapest, P.O. Box 49 (Hungary); Niemi, H. [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany); Xu, Z.; Rischke, D. H. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany)

    2010-08-15

    We solve the relativistic Riemann problem in viscous matter using the relativistic Boltzmann equation and the relativistic causal dissipative fluid-dynamical approach of Israel and Stewart. Comparisons between these two approaches clarify and point out the regime of validity of second-order fluid dynamics in relativistic shock phenomena. The transition from ideal to viscous shocks is demonstrated by varying the shear viscosity to entropy density ratio {eta}/s. We also find that a good agreement between these two approaches requires a Knudsen number Kn<1/2.

  13. Cosmos++: Relativistic Magnetohydrodynamics on Unstructured Grids with Local Adaptive Refinement

    SciTech Connect

    Anninos, P; Fragile, P C; Salmonson, J D

    2005-05-06

    A new code and methodology are introduced for solving the fully general relativistic magnetohydrodynamic (GRMHD) equations using time-explicit, finite-volume discretization. The code has options for solving the GRMHD equations using traditional artificial-viscosity (AV) or non-oscillatory central difference (NOCD) methods, or a new extended AV (eAV) scheme using artificial-viscosity together with a dual energy-flux-conserving formulation. The dual energy approach allows for accurate modeling of highly relativistic flows at boost factors well beyond what has been achieved to date by standard artificial viscosity methods. it provides the benefit of Godunov methods in capturing high Lorentz boosted flows but without complicated Riemann solvers, and the advantages of traditional artificial viscosity methods in their speed and flexibility. Additionally, the GRMHD equations are solved on an unstructured grid that supports local adaptive mesh refinement using a fully threated oct-tree (in three dimensions) network to traverse the grid hierarchy across levels and immediate neighbors. A number of tests are presented to demonstrate robustness of the numerical algorithms and adaptive mesh framework over a wide spectrum of problems, boosts, and astrophysical applications, including relativistic shock tubes, shock collisions, magnetosonic shocks, Alfven wave propagation, blast waves, magnetized Bondi flow, and the magneto-rotational instability in Kerr black hole spacetimes.

  14. Cosmos++: Relativistic Magnetohydrodynamics on Unstructured Grids with Local Adaptive Refinement

    E-print Network

    Peter Anninos; P. Chris Fragile; Jay D. Salmonson

    2005-09-09

    A new code and methodology are introduced for solving the general relativistic magnetohydrodynamic (GRMHD) equations in fixed background spacetimes using time-explicit, finite-volume discretization. The code has options for solving the GRMHD equations using traditional artificial-viscosity (AV) or non-oscillatory central difference (NOCD) methods, or a new extended AV (eAV) scheme using artificial-viscosity together with a dual energy-flux-conserving formulation. The dual energy approach allows for accurate modeling of highly relativistic flows at boost factors well beyond what has been achieved to date by standard artificial viscosity methods. It provides the benefit of Godunov methods in capturing high Lorentz boosted flows but without complicated Riemann solvers, and the advantages of traditional artificial viscosity methods in their speed and flexibility. Additionally, the GRMHD equations are solved on an unstructured grid that supports local adaptive mesh refinement using a fully threaded oct-tree (in three dimensions) network to traverse the grid hierarchy across levels and immediate neighbors. A number of tests are presented to demonstrate robustness of the numerical algorithms and adaptive mesh framework over a wide spectrum of problems, boosts, and astrophysical applications, including relativistic shock tubes, shock collisions, magnetosonic shocks, Alfven wave propagation, blast waves, magnetized Bondi flow, and the magneto-rotational instability in Kerr black hole spacetimes.

  15. The spectrum of cosmic rays escaping from relativistic shocks

    SciTech Connect

    Katz, Boaz; Waxman, Eli [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 76100 (Israel); Mészáros, Peter, E-mail: boaz.katz@weizmann.ac.il, E-mail: nnp@astro.psu.edu, E-mail: eli.waxman@weizmann.ac.il [Department of Astronomy and Astrophysics, Department of Physics, Center for Particle Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

    2010-10-01

    We derive expressions for the time integrated spectrum of Cosmic Rays (CRs) that are accelerated in a decelerating relativistic shock wave and escape ahead of the shock. It is assumed that at any given time the CRs have a power law form, carry a constant fraction of the energy E of the shocked plasma, and escape continuously at the maximal energy attainable. The spectrum of escaping particles is highly sensitive to the instantaneous spectral index due to the fact that the minimal energy, ?{sub min} ? ?{sup 2}m{sub p}c{sup 2} where ? is the shock Lorentz factor, changes with time. In particular, the escaping spectrum may be considerably harder than the canonical N(?)??{sup ?2} spectrum. For a shock expanding into a plasma of density n, a spectral break is expected at the maximal energy attainable at the transition to non relativistic velocities, ? ? 10{sup 19}(?{sub B}/0.1)(n/1cm{sup ?3}){sup 1/6}(E/10{sup 51}erg){sup 1/3}eV where ?{sub B} is the fraction of the energy flux carried by the magnetic field. If ultra-high energy CRs are generated in decelerating relativistic blast waves arising from the explosion of stellar mass objects, their generation spectrum may therefore be different than the canonical N(?)??{sup ?2}.

  16. Theory of Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Vlahakis, Nektarios

    Relativistic jets can be modeled as magnetohydrodynamic flows. We analyze the related equations and discuss the involved acceleration mechanisms, their relation to the collimation, to the jet confinement by its environment, and to possible rarefaction waves triggered by pressure imbalances.

  17. Computer modeling of thoracic response to blast.

    PubMed

    Stuhmiller, J H; Chuong, C J; Phillips, Y Y; Dodd, K T

    1988-01-01

    Primary blast injury affects the gas-containing structures of the body. Damage to the lungs with resultant respiratory insufficiency and arterial embolization of air from alveolar pulmonary venous fistulae is the predominant cause of morbidity and mortality following high-level blast exposure. In an effort to generate a widely applicable damage-risk criterion for thoracic injury from blast we are developing a complex computer finite element model (FEM) of the thorax. Taking an engineering approach, a horizontal cross-section of the thorax is divided into small discrete units (finite elements) of homogeneous structure. The necessary physical properties (density, bulk modulus, etc.) are then determined for each element. Specifying the material constants and geometry of the elements, the computer can load the surface of the structure with some force-time function (blast pressure-time history) and calculate the resultant physical events such as displacement, compression, stress, strain, etc. Computer predictions of pressure wave phenomena in the lung parenchyma are compared with trans-bronchially measured pressures in blast-exposed animals. The model should prove useful in assessing the risk of blast injury in diverse overpressure environments and may give insight into pathophysiologic mechanisms and strategies for protection. PMID:3339675

  18. Relativistic klystrons

    SciTech Connect

    Allen, M.A.; Azuma, O.; Callin, R.S.; Deruyter, H.; Eppley, K.R.; Fant, K.S.; Fowkes, W.R.; Herrmannsfeldt, W.B.; Hoag, H.A.; Koontz, R.F.

    1989-03-01

    Experimental work is underway by a SLAC-LLNL-LBL collaboration to investigate the feasibility of using relativistic klystrons as a power source for future high gradient accelerators. Two different relativistic klystron configurations have been built and tested to date: a high grain multicavity klystron at 11.4 GHz and a low gain two cavity subharmonic buncher driven at 5.7 GHz. In both configurations power is extracted at 11.4 GHz. In order to understand the basic physics issues involved in extracting RF from a high power beam, we have used both a single resonant cavity and a multi-cell traveling wave structure for energy extraction. We have learned how to overcome our previously reported problem of high power RF pulse shortening, and have achieved peak RF power levels of 170 MW with the RF pulse of the same duration as the beam current pulse. 6 refs., 3 figs., 3 tabs.

  19. Air blast effects on concrete walls

    Microsoft Academic Search

    C. A. Kot; P. Turula

    1976-01-01

    The effects of airblast due to explosive detonation in close proximity of a concrete wall are investigated analytically. Estimates are obtained both for the spalling of the back-face of the concrete wall and for the overall wall response produced by the total impulsive load of the air blast. Assuming elastic wave propagation in the concrete wall, it is found that

  20. Blast wave from buried charges

    SciTech Connect

    Reichenbach, H.; Behrens, K. [Fraunhofer-Institut fuer Kurzzeitdynamik - Ernst-Mach-Institut (EMI), Freiburg im Breisgau (Germany); Kuhl, A.L. [Lawrence Livermore National Lab., El Segundo, CA (United States)

    1993-08-01

    While much airblast data are available for height-of-burst (HOB) effects, systematic airblast data for depth-of-burst (DOB) effects are more limited. It is logical to ask whether the spherical 0.5-g Nitropenta charges that, proved to be successful for HOB tests at EMI are also suitable for experiments with buried charges in the laboratory scale; preliminary studies indicated in the alternative. Of special interest is the airblast environment generated by detonations just above or below the around surface. This paper presents a brief summary of the test results.

  1. Acceleration of Magnetospheric Relativistic Electrons by Ultra-Low Frequency Waves: A Comparison between Two Cases Observed by Cluster and LANL Satellites

    NASA Technical Reports Server (NTRS)

    Shao, X.; Fung, S. F.; Tan, L. C.; Sharma, A. S.

    2010-01-01

    Understanding the origin and acceleration of magnetospheric relativistic electrons (MREs) in the Earth's radiation belt during geomagnetic storms is an important subject and yet one of outstanding questions in space physics. It has been statistically suggested that during geomagnetic storms, ultra-low-frequency (ULF) Pc-5 wave activities in the magnetosphere are correlated with order of magnitude increase of MRE fluxes in the outer radiation belt. Yet, physical and observational understandings of resonant interactions between ULF waves and MREs remain minimum. In this paper, we show two events during storms on September 25, 2001 and November 25, 2001, the solar wind speeds in both cases were > 500 km/s while Cluster observations indicate presence of strong ULF waves in the magnetosphere at noon and dusk, respectively, during a approx. 3-hour period. MRE observations by the Los Alamos (LANL) spacecraft show a quadrupling of 1.1-1.5 MeV electron fluxes in the September 25, 2001 event, but only a negligible increase in the November 2.5, 2001 event. We present a detailed comparison between these two events. Our results suggest that the effectiveness of MRE acceleration during the September 25, 2001 event can be attributed to the compressional wave mode with strong ULF wave activities and the physical origin of MRE acceleration depends more on the distribution of toroidal and poloidal ULF waves in the outer radiation belt.

  2. Electron acceleration and emission in a field of a plane and converging dipole wave of relativistic amplitudes with the radiation reaction force taken into account

    SciTech Connect

    Bashinov, Aleksei V; Gonoskov, Arkady A; Kim, A V; Marklund, Mattias; Mourou, G; Sergeev, Aleksandr M

    2013-04-30

    A comparative analysis is performed of the electron emission characteristics as the electrons move in laser fields with ultra-relativistic intensity and different configurations corresponding to a plane or tightly focused wave. For a plane travelling wave, analytical expressions are derived for the emission characteristics, and it is shown that the angular distribution of the radiation intensity changes qualitatively even when the wave intensity is much less than that in the case of the radiation-dominated regime. An important conclusion is drawn that the electrons in a travelling wave tend to synchronised motion under the radiation reaction force. The characteristic features of the motion of electrons are found in a converging dipole wave, associated with the curvature of the phase front and nonuniformity of the field distribution. The values of the maximum achievable longitudinal momenta of electrons accelerated to the centre, as well as their distribution function are determined. The existence of quasi-periodic trajectories near the focal region of the dipole wave is shown, and the characteristics of the emission of both accelerated and oscillating electrons are analysed. (extreme light fields and their applications)

  3. Determination of explosive blast loading equivalencies with an explosively driven shock tube

    SciTech Connect

    Jackson, Scott I [Los Alamos National Laboratory; Hill, Larry G [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory

    2009-01-01

    Recently there has been significant interest in evaluating the potential of many different non-ideal energetic materials to cause blast damage. We present a method intended to quantitatively compare the blast loading generated by different energetic materials through use of an explosively driven shock tube. The test explosive is placed at the closed breech end of the tube and initiated with a booster charge. The resulting shock waves are then contained and focused by the tube walls to form a quasi-one-dimensional blast wave. Pressure transducers along the tube wall measure the blast overpressure versus distance from the source and allow the use of the one-dimensional blast scaling relationship to determine the energy deposited into the blast wave per unit mass of test explosive. These values are then compared for different explosives of interest and to other methods of equivalency determination.

  4. Determination of Explosive Blast Loading Equivalencies with an Explosively Driven Shock Tube

    NASA Astrophysics Data System (ADS)

    Jackson, Scott; Hill, Larry; Morris, John

    2009-06-01

    Recently there has been significant interest in evaluating the potential of many different non-ideal energetic materials to cause blast damage. We present a method intended to quantitatively compare the blast loading generated by different energetic materials through use of an explosively driven shock tube. The test explosive is placed at the closed breech end of the tube and initiated with a booster charge. The resulting shock waves are then contained and focused by the tube walls to form a quasi-one-dimensional blast wave. Pressure transducers along the tube wall measure the blast overpressure versus distance from the source and allow the use of the one-dimensional blast scaling relationship to determine the energy deposited into the blast wave per unit mass of test explosive. These values are then compared for different explosives of interest and compared to other methods of equivalency determination.

  5. Determination of Explosive Blast Loading Equivalencies with AN Explosively Driven Shock Tube

    NASA Astrophysics Data System (ADS)

    Jackson, Scott I.; Morris, John S.; Hill, Larry G.

    2009-12-01

    Recently there has been significant interest in evaluating the potential of many different non-ideal energetic materials to cause blast damage. We present a method intended to quantitatively compare the blast loading generated by different energetic materials through use of an explosively driven shock tube. The test explosive is placed at the closed breech end of the tube and initiated with a booster charge. The resulting shock waves are then contained and focused by the tube walls to form a quasi-one-dimensional blast wave. Pressure transducers along the tube wall measure the blast overpressure versus distance from the source and allow the use of the one-dimensional blast scaling relationship to determine the energy deposited into the blast wave per unit mass of test explosive. These values were measured for C4, ANFO, and two perchlorate explosives. Explosive equivalencies from these values were found to agree with prior theory and experiment.

  6. Blast furnace stove control

    SciTech Connect

    Muske, K.R. [Villanova Univ., PA (United States). Dept. of Chemical Engineering; Hansen, G.A.; Howse, J.W.; Cagliostro, D.J. [Los Alamos National Lab., NM (United States); Chaubal, P.C. [Inland Steel Industries Inc., East Chicago, IN (United States). Research Labs.

    1998-12-31

    This paper outlines the process model and model-based control techniques implemented on the hot blast stoves for the No. 7 Blast Furnace at the Inland Steel facility in East Chicago, Indiana. A detailed heat transfer model of the stoves is developed. It is then used as part of a predictive control scheme to determine the minimum amount of fuel necessary to achieve the blast air requirements. The controller also considers maximum and minimum temperature constraints within the stove.

  7. Relativistic electron acceleration by compressional-mode ULF waves: Evidence from correlated Cluster, Los Alamos National Laboratory spacecraft, and ground-based magnetometer measurements

    NASA Astrophysics Data System (ADS)

    Tan, Lun C.; Shao, X.; Sharma, A. S.; Fung, Shing F.

    2011-07-01

    Simultaneous observations by Cluster and Los Alamos National Laboratory (LANL) spacecraft and Canadian Array for Real-Time Investigations of Magnetic Activity and International Monitor for Auroral Geomagnetic Effects magnetometer arrays during a sudden storm commencement on 25 September 2001 show evidence of relativistic electron acceleration by compressional-mode ULF waves. The waves are driven by the quasiperiodic solar wind dynamical pressure fluctuations that continuously buffet the magnetosphere for ˜3 h. The compressional-mode ULF waves are identified by comparing the power of magnetic field magnitude fluctuations with the total magnetic field power. The radial distribution and azimuthal propagation of both toroidal and poloidal-mode ULF waves are derived from ground-based magnetometer data. The energetic electron fluxes measured by LANL show modulation of low-energy electrons and acceleration of high-energy electrons by the compressional poloidal-mode electric field oscillations. The energy threshold of accelerated electrons at the geosynchronous orbit is ˜0.4 MeV, which is roughly consistent with drift-resonant interaction of magnetospheric electrons with compressional-mode ULF waves.

  8. A two-channel relativistic backward-wave generator with 8-mm range, controllable phase difference, and channel power of 230 MW

    NASA Astrophysics Data System (ADS)

    El'chaninov, A. A.; Klimov, A. I.; Romanchenko, I. V.; Rostov, V. V.; Pedos, M. S.; Rukin, S. N.; Sharypov, K. A.; Shpak, V. G.; Shunailov, S. A.; Ul'maskulov, M. R.; Yalandin, M. I.

    2013-10-01

    The coherent composition of the wave beams of two relativistic nanosecond backward-wave tubes (BWTs) with an 8-mm range and peak power in each channel of up to 230 MW is implemented. A specific feature of this experiment was power supply of explosive-emission cathodes by split pulses supplied by a completely solid-phase SOS modulator with reduced amplitude scatter. The voltage growth rate was increased compared to previous experiments, which made it possible to transition to the region of weaker magnetic fields ˜2 T, which was less than cyclotron resonance field, while retaining stable emission of the electron beams. As a result, a standard deviation of phase scatter between the channels of 0.5 ps was found on the time scale.

  9. Computer cast blast modelling

    Microsoft Academic Search

    S. Chung; M. McGill; D. S. Preece

    1994-01-01

    Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. The more overburden removed by explosives, the less blasted material there is left to be transported with mechanical equipment, such as draglines and trucks. In order to optimize the percentage of rock that is cast, a higher powder factor than

  10. Lightweight blast shield

    DOEpatents

    Mixon, Larry C. (Madison, AL); Snyder, George W. (Huntsville, AL); Hill, Scott D. (Toney, AL); Johnson, Gregory L. (Decatur, AL); Wlodarski, J. Frank (Huntsville, AL); von Spakovsky, Alexis P. (Huntsville, AL); Emerson, John D. (Arab, AL); Cole, James M. (Huntsville, AL); Tipton, John P. (Huntsville, AL)

    1991-01-01

    A tandem warhead missile arrangement that has a composite material housing structure with a first warhead mounted at one end and a second warhead mounted near another end of the composite structure with a dome shaped composite material blast shield mounted between the warheads to protect the second warhead from the blast of the first warhead.

  11. Experimental Studies of Mitigation Materials for Blast Induced TBI

    NASA Astrophysics Data System (ADS)

    Alley, Matthew; Son, Steven

    2009-06-01

    The objective of this experimental study is to compare the effects of various materials obstructing the flow of a blast wave and the ability of the given material to reduce the damage caused by the blast. Several methods of energy transfer in blast wave flows are known or expected including: material interfaces with impedance mismatches, density changes in a given material, internal shearing, and particle fracture. The theory applied to this research is that the greatest energy transfer within the obstructing material will yield the greatest mitigation effects to the blast. Sample configurations of foam were varied to introduce material interfaces and filler materials with varying densities and impedances (liquids and powders). The samples were loaded according to a small scale blast produced by an explosive driven shock tube housing gram-range charges. The transmitted blast profiles were analyzed for variations in impulse characteristics and frequency components as compared to standard free field profiles. The results showed a rounding effect of the transmitted blast profile for all samples with the effects of the low density fillers surpassing all others tested.

  12. A computational study on brain tissue under blast: primary and tertiary blast injuries.

    PubMed

    Rezaei, A; Salimi Jazi, M; Karami, G; Ziejewski, M

    2014-08-01

    In this paper, a biomechanical study of a human head model exposed to blast shock waves followed by a blunt impact with the surface of the enclosing walls of a confined space is carried out. Under blast, the head may experience primary blast injury (PBI) due to exposure to the shockwaves and tertiary blast injury (TeBI) due to a possible blunt impact. We examine the brain response data in a deformable finite element head model in terms of the inflicted stress/pressure, velocity, and acceleration on the brain for several blast scenarios with different intensities. The data will be compared for open space and confined spaces. Following the initial impact of the shock front in the confined space, one can see the fluctuations in biomechanical data due to wave reflections. Although the severity of the PBI and TeBI is dependent on the situation, for the cases studied here, PBI is considerably more pronounced than TeBI in confined spaces. PMID:24515869

  13. Dynamic response of containment vessels to blast loading

    SciTech Connect

    Karpp, R.R.; Duffey, T.A.; Neal, T.R.; Warnes, R.H.; Thompson, J.D.

    1982-01-01

    The dynamic response of steel, spherical containment vessels loaded by internal explosive blast was studied by experiments, computations, and analysis. Instrumentation used in the experiments consisted of strain and pressure gauges and a velocity interferometer. Data were used to rank the blast wave mitigating properties of several filler materials and to develop a scaling law relating strain, filler material, and explosive energy or explosive mass.

  14. On the efficiency of semi-closed blast inhibitors

    NASA Astrophysics Data System (ADS)

    Gelfand, B. E.; Silnikov, M. V.; Chernyshov, M. V.

    2010-08-01

    Numerical efficiency analysis of those blast inhibitors (BI) consisting of a vertical cylinder open at the top is presented and compared with the existing data from other authors. It was proven computationally that such low-height “semi-closed” BI do not provide blast wave suppression according to the minimum practical requirements (overpressure and pressure impulse reduction at several times) and, if one wishes to compare, other existing criteria (Bowen injury diagrams and similar guidelines adopted in different countries).

  15. Gyrotrons and dopplertrons - Electromagnetic wave generators based on coherent radiation from magneto-resonant, relativistic, electron beams

    Microsoft Academic Search

    V. L. Granatstein

    1978-01-01

    The application of magnetized, intense, relativistic-electron beams to the generation of electromagnetic radiation at wavelengths ranging from 10 cm down to a fraction of a millimeter has enabled significant advances to be made in peak power capabilities. The physical mechanisms are conveniently divided into three categories according to the experimental feature which determines the output wavelength. These categories are related

  16. Characterization of Viscoelastic Materials for Low-Magnitude Blast Mitigation

    NASA Astrophysics Data System (ADS)

    Bartyczak, Susan; Mock, Willis

    2013-06-01

    Recent preliminary research indicates that exposure to low amplitude blast waves, such as from IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficiently protecting warfighters from this danger and the effects are debilitating, costly, and long-lasting. The objective of this research is to evaluate the blast mitigating behavior of current helmet materials and new materials designed for blast mitigation using a test fixture recently developed at the Naval Surface Warfare Center Dahlgren Division for use with an existing gas gun. A 40-mm-bore gas gun is used as a shock tube to generate blast waves (ranging from 5 to 30 psi) in a test fixture mounted at the gun muzzle. A fast opening valve is used to release helium gas from a breech which forms into a blast wave and impacts instrumented targets in the test fixture. Blast attenuation of selected materials is determined through the measurement of pressure and accelerometer data in front of and behind the target. Materials evaluated in this research include 6061-T6 aluminum, polyurea 1000, Styrofoam, and Sorbothane (durometer 50, shore 00). The experimental technique, calibration and checkout procedures, and results will be presented.

  17. Investigation of blast-induced traumatic brain injury

    PubMed Central

    Ludwigsen, John S.; Ford, Corey C.

    2014-01-01

    Objective Many troops deployed in Iraq and Afghanistan have sustained blast-related, closed-head injuries from being within non-lethal distance of detonated explosive devices. Little is known, however, about the mechanisms associated with blast exposure that give rise to traumatic brain injury (TBI). This study attempts to identify the precise conditions of focused stress wave energy within the brain, resulting from blast exposure, which will correlate with a threshold for persistent brain injury. Methods This study developed and validated a set of modelling tools to simulate blast loading to the human head. Using these tools, the blast-induced, early-time intracranial wave motions that lead to focal brain damage were simulated. Results The simulations predict the deposition of three distinct wave energy components, two of which can be related to injury-inducing mechanisms, namely cavitation and shear. Furthermore, the results suggest that the spatial distributions of these damaging energy components are independent of blast direction. Conclusions The predictions reported herein will simplify efforts to correlate simulation predictions with clinical measures of TBI and aid in the development of protective headwear. PMID:24766453

  18. An animal-to-human scaling law for blast-induced traumatic brain injury risk assessment.

    PubMed

    Jean, Aurélie; Nyein, Michelle K; Zheng, James Q; Moore, David F; Joannopoulos, John D; Radovitzky, Raúl

    2014-10-28

    Despite recent efforts to understand blast effects on the human brain, there are still no widely accepted injury criteria for humans. Recent animal studies have resulted in important advances in the understanding of brain injury due to intense dynamic loads. However, the applicability of animal brain injury results to humans remains uncertain. Here, we use advanced computational models to derive a scaling law relating blast wave intensity to the mechanical response of brain tissue across species. Detailed simulations of blast effects on the brain are conducted for different mammals using image-based biofidelic models. The intensity of the stress waves computed for different external blast conditions is compared across species. It is found that mass scaling, which successfully estimates blast tolerance of the thorax, fails to capture the brain mechanical response to blast across mammals. Instead, we show that an appropriate scaling variable must account for the mass of protective tissues relative to the brain, as well as their acoustic impedance. Peak stresses transmitted to the brain tissue by the blast are then shown to be a power function of the scaling parameter for a range of blast conditions relevant to TBI. In particular, it is found that human brain vulnerability to blast is higher than for any other mammalian species, which is in distinct contrast to previously proposed scaling laws based on body or brain mass. An application of the scaling law to recent experiments on rabbits furnishes the first physics-based injury estimate for blast-induced TBI in humans. PMID:25267617

  19. New blast weapons.

    PubMed

    Dearden, P

    2001-02-01

    Over the last decade a large number of weapon systems have appeared that use blast as their primary damage mechanism. This is a notable trend; until recently very few warheads relied on blast as their primary output. Most warheads in service use explosives to drive metal such as fragments and shaped charge jets to engage targets. New technologies are now being integrated into warheads that claim to have enhanced blast performance. Blast weapons could have been designed to fill a gap in capability; they are generally used for the attack of 'soft' targets including personnel, both in the open and within protective structures. With the increased number and range of these weapons, it is likely that UK forces will have to face them in future conflicts. This paper briefly describes fuel-air explosive blast weapons and reviews a range of enhanced blast weapons that have been developed recently. The paper concludes with a brief discussion on the reasons why enhanced blast technologies may be proliferating and how this could affect the Defence Medical Services. PMID:11307681

  20. 30 CFR 75.1323 - Blasting circuits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...MINES Explosives and Blasting § 75.1323 Blasting circuits. (a) Blasting circuits shall be protected from sources of stray electric current. (b) Detonators made by different manufacturers shall not be combined in the same blasting...

  1. Powerful electromagnetic millimeter-wave oscillations produced by stimulated scattering of microwave radiation by relativistic electron beams

    Microsoft Academic Search

    G. G. Denisov; A. V. Smorgonskii; V. P. Gubanov; S. D. Korovin; V. V. Rostov; M. I. Yalandin

    1984-01-01

    The stimulated scattering of electromagnetic waves in microwave generators, in which a high-current electron beam excites either a backward wave (BWO) or a quasi-critical frequency wave (orotron) is investigated experimentally. The scattering occurs at the same electron beam and the high-frequency feedback is provided by the inhomogeneities of the electrodynamic system of the microwave generator itself. A power of several

  2. Ion-acoustic waves in a plasma consisting of adiabatic warm ions, nonisothermal electrons, and a weakly relativistic electron beam: Linear and higher-order nonlinear effects

    SciTech Connect

    Esfandyari-Kalejahi, A. [Faculty of Science, Department of Physics, Azerbaijan University of Tarbiat Moallem, 51745-406 Tabriz (Iran, Islamic Republic of); Kourakis, I. [Center for Plasma Physics (CPP), Department of Physics and Astronomy, Queen's University Belfast, BT7 1 NN Northern Ireland (United Kingdom); Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Shukla, P. K. [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

    2008-02-15

    The nonlinear propagation of finite amplitude ion acoustic solitary waves in a plasma consisting of adiabatic warm ions, nonisothermal electrons, and a weakly relativistic electron beam is studied via a two-fluid model. A multiple scales technique is employed to investigate the nonlinear regime. The existence of the electron beam gives rise to four linear ion acoustic modes, which propagate at different phase speeds. The numerical analysis shows that the propagation speed of two of these modes may become complex-valued (i.e., waves cannot occur) under conditions which depend on values of the beam-to-background-electron density ratio {alpha}, the ion-to-free-electron temperature ratio {sigma}, and the electron beam velocity v{sub 0}; the remaining two modes remain real in all cases. The basic set of fluid equations are reduced to a Schamel-type equation and a linear inhomogeneous equation for the first and second-order potential perturbations, respectively. Stationary solutions of the coupled equations are derived using a renormalization method. Higher-order nonlinearity is thus shown to modify the solitary wave amplitude and may also deform its shape, even possibly transforming a simple pulse into a W-type curve for one of the modes. The dependence of the excitation amplitude and of the higher-order nonlinearity potential correction on the parameters {alpha}, {sigma}, and v{sub 0} is numerically investigated.

  3. Wind-tunnel shock-tube simulation and evaluation of blast effects on an engine inlet. Final report, October 1975December 1977

    Microsoft Academic Search

    J. R. Ruetenik; R. F. Smiley

    1978-01-01

    This report describes a program for simulating blast wave intercepts with a scaled aircraft engine in subsonic flight, using the shock tube technique for firing the blast-type waves. Three large 22.6 inch-diameter shock tubes were installed in the AEDC 16T (16 ft sq) transonic wind tunnel and were used to project blast waves at a 0.1-scale B-1 aircraft model. Forty-five

  4. Study of TATP: blast characteristics and TNT equivalency of small charges

    NASA Astrophysics Data System (ADS)

    Pachman, J.; Matyáš, R.; Künzel, M.

    2014-07-01

    Blast wave parameters including incident overpressure, impulse and duration of the positive phase of the incident blast wave and its time of arrival were experimentally determined for 50 g charges of low bulk density () dry TATP (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane). The results were compared with published TNT data, and TNT equivalencies were determined, resulting in the values of 70 % based on overpressure and 55 % based on impulse of the positive phase of the blast wave. Brisance by the Hess method (lead cylinder compression) was found to be about one-third of that for TNT (at density . Detonation velocities averaged around

  5. Relativistic Effects on Chemical Properties.

    ERIC Educational Resources Information Center

    McKelvey, Donald R.

    1983-01-01

    Discusses how anomalous chemical properties may be explained by considering relativistic effects. Traces development of the relativistic wave equation (Dirac equation) starting with the Borh treatment of the hydrogen atom and discusses major consequences of the Dirac equation. Suggests that these topics receive greater attention in the…

  6. Pressure sensing system for the study of blast-induced traumatic brain injury

    Microsoft Academic Search

    X. Meng; D. K. Cullen; M. R. Tofighi; A. Rosen

    2011-01-01

    Due to extensive use of explosive weaponry, wars in Iraq and Afghanistan have led to a significant increase in blast-induced injuries, which manifest as complicated neural cellular damage. This research is serving two purposes: 1. verifying a methodology to measure the physical characteristics of the blast waves by using a MEMS capacitor pressure sensor and 2. performing In-Vivo study for

  7. Hybrid S2/Carbon Epoxy Composite Armours Under Blast Loads

    NASA Astrophysics Data System (ADS)

    Dolce, F.; Meo, Michele; Wright, A.; French, M.; Bernabei, M.

    2012-06-01

    Civil and military structures, such as helicopters, aircrafts, naval ships, tanks or buildings are susceptible to blast loads as terroristic attacks increases, therefore there is the need to design blast resistant structures. During an explosion the peak pressure produced by shock wave is much greater than the static collapse pressure. Metallic structures usually undergo large plastic deformations absorbing blast energy before reaching equilibrium. Due to their high specific properties, fibre-reinforced polymers are being considered for energy absorption applications in blast resistant armours. A deep insight into the relationship between explosion loads, composite architecture and deformation/fracture behaviour will offer the possibility to design structures with significantly enhanced energy absorption and blast resistance performance. This study presents the results of a numerical investigation aimed at understanding the performance of a hybrid composite (glass/carbon fibre) plate subjected to blast loads using commercial LS-DYNA software. In particular, the paper deals with numerical 3D simulations of damages caused by air blast waves generated by C4 charges on two fully clamped rectangular plates made of steel and hybrid (S2/Carbon) composite, respectively. A Multi Materials Arbitrary Lagrangian Eulerian (MMALE) formulation was used to simulate the shock phenomenon. For the steel plates, the Johnson-Cook material model was employed. For the composite plates both in-plane and out-of-plane failure criteria were employed. In particular, a contact tiebreak formulation with a mixed mode failure criteria was employed to simulate delamination failure. As for the steel plates the results showed that excellent correlation with the experimental data for the two blast load conditions in terms of dynamic and residual deflection for two different C4 charges. For the composite plates the numerical results showed that, as expected, a wider delamination damage was observed for the higher blast loads case. Widespread tensile matrix damage was experienced for both blast load cases, while only for 875 g blast load fiber failure damage was observed. This agrees well with the experimental data showing that the composite panel was not able to resist to the 875 g blast load.

  8. In vitro studies of primary explosive blast loading on neurons.

    PubMed

    Zander, Nicole E; Piehler, Thuvan; Boggs, Mary E; Banton, Rohan; Benjamin, Richard

    2015-09-01

    In a military setting, traumatic brain injury (TBI) is frequently caused by blast waves that can trigger a series of neuronal biochemical changes. Although many animal models have been used to study the effects of primary blast waves, elucidating the mechanisms of damage in a whole-animal model is extremely complex. In vitro models of primary blast, which allow for the deconvolution of mechanisms, are relatively scarce. It is largely unknown how structural damage at the cellular level impacts the functional activity at variable time scales after the TBI event. A novel in vitro system was developed to probe the effects of explosive blast (ranging from ?25 to 40 psi) on dissociated neurons. PC12 neurons were cultured on laminin-coated substrates, submerged underwater, and subjected to single and multiple blasts in a controlled environment. Changes in cell membrane permeability, viability, and cell morphology were evaluated. Significant increases in axonal beading were observed in the injured cells. In addition, although cell death was minimal after a single insult, cell viability decreased significantly following repeated blast exposure. © 2015 Wiley Periodicals, Inc. PMID:25914380

  9. Point form relativistic quantum mechanics and relativistic SU(6)

    NASA Technical Reports Server (NTRS)

    Klink, W. H.

    1993-01-01

    The point form is used as a framework for formulating a relativistic quantum mechanics, with the mass operator carrying the interactions of underlying constituents. A symplectic Lie algebra of mass operators is introduced from which a relativistic harmonic oscillator mass operator is formed. Mass splittings within the degenerate harmonic oscillator levels arise from relativistically invariant spin-spin, spin-orbit, and tensor mass operators. Internal flavor (and color) symmetries are introduced which make it possible to formulate a relativistic SU(6) model of baryons (and mesons). Careful attention is paid to the permutation symmetry properties of the hadronic wave functions, which are written as polynomials in Bargmann spaces.

  10. Relativistic Hall effect.

    PubMed

    Bliokh, Konstantin Y; Nori, Franco

    2012-03-23

    We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin-Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices and mechanical flywheels and also discuss various fundamental aspects of this phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales, from elementary spinning particles, through classical light, to rotating black holes. PMID:22540559

  11. Relativistic Hall Effect

    E-print Network

    Konstantin Y. Bliokh; Franco Nori

    2012-02-03

    We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the correct Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices, and mechanical flywheels, and also discuss various fundamental aspects of this phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales: from elementary spinning particles, through classical light, to rotating black-holes.

  12. Relativistic Hall Effect

    NASA Astrophysics Data System (ADS)

    Bliokh, Konstantin Y.; Nori, Franco

    2012-03-01

    We consider the relativistic deformation of quantum waves and mechanical bodies carrying intrinsic angular momentum (AM). When observed in a moving reference frame, the centroid of the object undergoes an AM-dependent transverse shift. This is the relativistic analogue of the spin-Hall effect, which occurs in free space without any external fields. Remarkably, the shifts of the geometric and energy centroids differ by a factor of 2, and both centroids are crucial for the Lorentz transformations of the AM tensor. We examine manifestations of the relativistic Hall effect in quantum vortices and mechanical flywheels and also discuss various fundamental aspects of this phenomenon. The perfect agreement of quantum and relativistic approaches allows applications at strikingly different scales, from elementary spinning particles, through classical light, to rotating black holes.

  13. Identifying and Characterizing Blasts from recordings at USArray stations

    NASA Astrophysics Data System (ADS)

    Astiz, L.; Vernon, F.; Martynov, V. G.; Tytell, J.; Cox, T. A.; Reyes, J. C.; Eakins, J. A.

    2013-12-01

    As the traverse of EarthScope USArray stations draws to an end, the Array Network Facility (ANF) has located nearly 60,000 seismic events in the continental U.S. since April 2004. The ANF seismic bulletin is complete to MR ~ 2.1 but does not distinguish between earthquakes and blasts. In contrast to regional seismic catalogs in the U.S. that mostly report naturally occurring seismicity with varying magnitude thresholds. Then, it is not surprising that only half of the events reported by ANF are associated with those reported by regional networks. By considering the local time of occurrence of events in the ANF bulletin, we conclude that mining blasts may comprise up to a third of the events reported. So in order to use the ANF bulletin to study naturally occurring seismicity in the continental U.S., it is important to identify blasts as such in the bulletin. Ideally, mine blasts can be identify as such in the ANF bulletin by getting ground truth information from mining operation, or by associating event origins with origins in the U.S.G.S. mining catalog. However, only a small portion of events can be identified in this manner. So by consider local time of occurrence, together with the cross correlation value of events occurring within 10 km of active mines as well as waveform characteristics from recordings at USArray stations located within 300 km to these events, we may be able to identify many more events, specially ones with lower magnitudes, as having been generated by mine blasting for a particular region. Once events have been identified as blasts, or probable blasts, we will analyze if waveform characteristics from blasts from surface or underground mines by analyzing the frequency content of waveforms at stations at similar ranges. In addition, we explore if mining blasts can provide a good data set to characterize wave propagation on different tectonic regimes in the continental U.S.

  14. Experimental magnesium depletion in adult rabbits caused by blast overpressure.

    PubMed

    Cernak, I; Radosevic, P; Malicevic, Z; Savic, J

    1995-09-01

    The complex pressure wave (blast) generated by some explosions causes pulmonary pathological changes which resemble the histological findings of the adult respiratory distress syndrome (ARDS). The development of indirect neurotrauma following experimental pulmonary blast injury has been shown previously. The purpose of this study was to evaluate lung and brainstem total tissue magnesium concentrations in adult rabbits following pulmonary blast injury. In order to assess the interrelationship between magnesium and other secondary injury factors, total calcium and high energy phosphate (phosphocreatine, PCr; adenosine triphosphate, ATP) contents were simultaneously measured. Twenty adult male rabbits were divided into two groups. Group C (n = 10) served as control, while group B (n = 10) was subjected to a focused blast wave, generated in laboratory conditions using an air-driven shock tube. Moderate pulmonary blast injury was verified by histological examination in group B. Total tissue magnesium and calcium contents were measured by atomic absorption spectrophotometry in the lungs and brainstem of adult rabbits 30 min following blast overpressure and in their uninjured controls. Simultaneously, PCr and ATP contents were measured by fluorimetric enzymatic analyses in same structures. Lung and brainstem water contents were determined by wet weight to dry weight ratio. Blast overpressure to the lungs induced significant magnesium depletion, increased calcium and decreased the Mg/Ca ratio in lung tissue of injured animals. Increases in water content and PCr/ATP ratio were also observed. Significant correlations between these Mg/Ca and PCr/ATP and between Mg and ATP parameters confirmed the functional relationship between magnesium depletion and impaired bioenergetic state in indirect neurotrauma in adult rabbits through blast overpressure. PMID:8845290

  15. NRQCD matrix elements for S-wave bottomonia and Gamma[eta_b(nS) -> gamma gamma] with relativistic corrections

    E-print Network

    Hee Sok Chung; Jungil Lee; Chaehyun Yu

    2011-02-03

    We determine the leading-order nonrelativistic quantum chromodynamics (NRQCD) matrix element _Upsilon and the ratio _Upsilon, for Upsilon=Upsilon(nS) with n=1, 2, and 3 by comparing the measured values for Gamma[Upsilon -> e^+ e^-] with the NRQCD factorization formula in which relativistic corrections are resummed to all orders in the heavy-quark velocity v. The values for _Upsilon, which is the ratio of order-v^2 matrix element to _Upsilon, are new. They can be used for NRQCD predictions involving Upsilon(nS) and eta_b(nS) with relativistic corrections. As an application, we predict the two-photon decay rates for the spin-singlet states: Gamma[eta_b(1S) -> gamma gamma] = 0.512^{+0.096}_{-0.094} keV, Gamma[eta_b(2S) -> gamma gamma] = 0.235^{+0.043}_{-0.043} keV, and Gamma[eta_b(3S) -> gamma gamma] = 0.170^{+0.031}_{-0.031} keV.

  16. Large blast and thermal simulator advanced concept driver design by computational fluid dynamics. Final report, 1987-1989

    SciTech Connect

    Opalka, K.O.

    1989-08-01

    The construction of a large test facility has been proposed for simulating the blast and thermal environment resulting from nuclear explosions. This facility would be used to test the survivability and vulnerability of military equipment such as trucks, tanks, and helicopters in a simulated thermal and blast environment, and to perform research into nuclear blast phenomenology. The proposed advanced design concepts, heating of driver gas and fast-acting throat valves for wave shaping, are described and the results of CFD studies to advance these new technical concepts fro simulating decaying blast waves are reported.

  17. Low Level Primary Blast Injury in Rodent Brain

    PubMed Central

    Pun, Pamela B. L.; Kan, Enci Mary; Salim, Agus; Li, Zhaohui; Ng, Kian Chye; Moochhala, Shabbir M.; Ling, Eng-Ang; Tan, Mui Hong; Lu, Jia

    2011-01-01

    The incidence of blast attacks and resulting traumatic brain injuries has been on the rise in recent years. Primary blast is one of the mechanisms in which the blast wave can cause injury to the brain. The aim of this study was to investigate the effects of a single sub-lethal blast over pressure (BOP) exposure of either 48.9?kPa (7.1?psi) or 77.3?kPa (11.3?psi) to rodents in an open-field setting. Brain tissue from these rats was harvested for microarray and histopathological analyses. Gross histopathology of the brains showed that cortical neurons were “darkened” and shrunken with narrowed vasculature in the cerebral cortex day 1 after blast with signs of recovery at day 4 and day 7 after blast. TUNEL-positive cells were predominant in the white matter of the brain at day 1 after blast and double-labeling of brain tissue showed that these DNA-damaged cells were both oligodendrocytes and astrocytes but were mainly not apoptotic due to the low caspase-3 immunopositivity. There was also an increase in amyloid precursor protein immunoreactive cells in the white matter which suggests acute axonal damage. In contrast, Iba-1 staining for macrophages or microglia was not different from control post-blast. Blast exposure altered the expression of over 5786 genes in the brain which occurred mostly at day 1 and day 4 post-blast. These genes were narrowed down to 10 overlapping genes after time-course evaluation and functional analyses. These genes pointed toward signs of repair at day 4 and day 7 post-blast. Our findings suggest that the BOP levels in the study resulted in mild cellular injury to the brain as evidenced by acute neuronal, cerebrovascular, and white matter perturbations that showed signs of resolution. It is unclear whether these perturbations exist at a milder level or normalize completely and will need more investigation. Specific changes in gene expression may be further evaluated to understand the mechanism of blast-induced neurotrauma. PMID:21541261

  18. Degradation of Linearly Propagated Atomic-Blast Effects by Structures or Hilly Terrain

    Microsoft Academic Search

    1953-01-01

    The degradation factor was computed for linearly propagated blast waves (created by an atomic burst) striking a circular plot of land having a V-shaped or sawtooth type of contour and sinusoidal terrain.

  19. Shock (Blast) Mitigation by "Soft" Condensed Matter

    E-print Network

    Vitali F. Nesterenko

    2007-08-24

    It is a common point that "soft" condensed matter (like granular materials or foams) can reduce damage caused by impact or explosion. It is attributed to their ability to absorb significant energy. This is certainly the case for a quasistatic type of deformation at low velocity of impact where such materials are widely used for packing of fragile devices. At the same time a mitigation of blast phenomena must take into account shock wave properties of "soft" matter which very often exhibit highly nonlinear, highly heterogeneous and dissipative behavior. This paper considers applications of "soft" condensed matter for blast mitigation using simplified approach, presents analysis of some anomalous effects and suggestions for future research in this exciting area.

  20. Nonlinear theory of the parametrically resonant interaction of electromagnetic waves in a relativistic-electron-beam plasma - Fundamental equations

    Microsoft Academic Search

    I. V. Dzedolik; V. P. Zakharov; V. V. Kulish

    1988-01-01

    A one-dimensionally limited, transversely homogeneous model of an artificial magnetodielectric is used to obtain a system of self-consistent nonlinear truncated equations for the parametrically resonant interaction of electromagnetic waves in an REB plasma. All the various types of transverse, periodically reversing electromagnetic pump and signal fields are taken into account, and the polarization, dispersion, impedance, and phase characteristics of the

  1. A new scheme of causal viscous hydrodynamics for relativistic heavy-ion collisions: A Riemann solver for quark–gluon plasma

    SciTech Connect

    Akamatsu, Yukinao, E-mail: akamatsu@kmi.nagoya-u.ac.jp [Kobayashi–Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Nagoya 464-8602 (Japan)] [Kobayashi–Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Nagoya 464-8602 (Japan); Inutsuka, Shu-ichiro [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)] [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Nonaka, Chiho [Kobayashi–Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Nagoya 464-8602 (Japan) [Kobayashi–Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Nagoya 464-8602 (Japan); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Takamoto, Makoto [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan) [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Max-Planck-Institut für Kernphysik, Postfach 103980, 69029 Heidelberg (Germany)

    2014-01-01

    In this article, we present a state-of-the-art algorithm for solving the relativistic viscous hydrodynamics equation with the QCD equation of state. The numerical method is based on the second-order Godunov method and has less numerical dissipation, which is crucial in describing of quark–gluon plasma in high-energy heavy-ion collisions. We apply the algorithm to several numerical test problems such as sound wave propagation, shock tube and blast wave problems. In sound wave propagation, the intrinsic numerical viscosity is measured and its explicit expression is shown, which is the second-order of spatial resolution both in the presence and absence of physical viscosity. The expression of the numerical viscosity can be used to determine the maximum cell size in order to accurately measure the effect of physical viscosity in the numerical simulation.

  2. Dispersive characteristics and longitudinal resonance properties in a relativistic backward wave oscillator with the coaxial arbitrary-profile slow-wave structure

    Microsoft Academic Search

    Xingjun Ge; Huihuang Zhong; Baoliang Qian; Jun Zhang; Yuwei Fan; Ting Shu; Jinliang Liu

    2009-01-01

    The method for calculating the dispersion relations of the slow-wave structures (SWSs) with arbitrary geometrical structures is studied in detail by using the Fourier series expansion. In addition, dispersive characteristics and longitudinal resonance properties of the SWSs with the cosinusoidal, trapezoidal, and rectangular corrugations are analyzed by numerical calculation. Based on the above discussion, a comparison on an L-band coaxial

  3. Viscoelastic Materials Study for the Mitigation of Blast-Related Brain Injury

    NASA Astrophysics Data System (ADS)

    Bartyczak, Susan; Mock, Willis, Jr.

    2011-06-01

    Recent preliminary research into the causes of blast-related brain injury indicates that exposure to blast pressures, such as from IED detonation or multiple firings of a weapon, causes damage to brain tissue resulting in Traumatic Brain Injury (TBI) and Post Traumatic Stress Disorder (PTSD). Current combat helmets are not sufficient to protect the warfighter from this danger and the effects are debilitating, costly, and long-lasting. Commercially available viscoelastic materials, designed to dampen vibration caused by shock waves, might be useful as helmet liners to dampen blast waves. The objective of this research is to develop an experimental technique to test these commercially available materials when subject to blast waves and evaluate their blast mitigating behavior. A 40-mm-bore gas gun is being used as a shock tube to generate blast waves (ranging from 1 to 500 psi) in a test fixture at the gun muzzle. A fast opening valve is used to release nitrogen gas from the breech to impact instrumented targets. The targets consist of aluminum/ viscoelastic polymer/ aluminum materials. Blast attenuation is determined through the measurement of pressure and accelerometer data in front of and behind the target. The experimental technique, calibration and checkout procedures, and results will be presented.

  4. Blast trauma: the fourth weapon of mass destruction.

    PubMed

    Born, C T

    2005-01-01

    Injury from blast is becoming more common in the non-military population. This is primarily a result of an increase in politically motivated bombings within the civilian sector. Explosions unrelated to terrorism may also occur in the industrial setting. Civilian physicians and surgeons need to have an understanding of the pathomechanics and physiology of blast injury and to recognize the hallmarks of severity in order to increase survivorship. Because victims may be transported rapidly to the hospital, occult injury to gas and fluid containing organs (particularly the ears, bowel and lungs) may go unrecognized. Information surrounding the physical environment of the explosion (whether inside or outside, underwater, associated building collapse, etc) will prove useful. Most of the immediate deaths are caused by primary blast injury from the primary blast wave, but secondary blast injury from flying debris can also be lethal and involve a much wider radius. Liberal use of X-ray examination in areas of skin punctures will help to identify a need for exploration and/or foreign body removal. Biologic serum markers may have a role in identifying victims of primary blast injury and assist in monitoring their clinical progress. Tertiary blast injury results from the airborne propulsion of the victim by the shockwave and is a source of additional blunt head and torso trauma as well as fractures. Miscellaneous (quaternary) blast injury include thermal or dust inhalation exposure as well as crush and compartment syndromes from building collapse. Any explosion has the potential to be associated with nuclear, biologic or chemical contaminants, and this should remain a consideration for healthcare givers until proven otherwise. PMID:16425623

  5. Blast injuries--and the pivotal role of trauma surgeons.

    PubMed

    Luks, F I

    2010-01-01

    An explosion is the sudden release of energy and its radial propagation through air, solid structures and living tissue. Treatment of blast injuries is complex and combines the principles of penetrating and blunt trauma, chemical or thermal burns and disaster and mass casualty management. Primary blast injuries are a direct result of the explosion itself. The sudden release of energy is translated into a shock wave that travels at supersonic speed (5000 metres/second). There is a sudden and short-lived rise in pressure, followed by a prolonged negative pressure, or vacuum, responsible for additional injury. The organs most at risk for primary blast injuries are the lungs, the ears and the gastrointestinal tract. The explosion also sets solid objects in motion; these act as projectiles, and can travel over far greater distances (secondary blast injuries), and their management is no different from penetrating or blunt trauma from other causes. The explosion may cause not only "projectiles," but the body itself to be displaced: These tertiary blast injuries include traumatic amputations and crush injuries following land mine explosions. Finally, quaternary blast injuries comprise other forms of associated trauma, such as burns, asphyxia or poisoning from release of noxious substances by the blast. These injuries can be particularly taxing for rescue teams because of their tendency to affect large amounts of patients and the risk they pose to the rescuers themselves. Individual management of the blast injury victim requires a multidisciplinary team; terrorist or wartime bombings also require expertise in disaster management and triage. PMID:21158326

  6. Blast attenuation in Cymat foam core sacrificial claddings

    Microsoft Academic Search

    D. Karagiozova; G. S. Langdon; G. N. Nurick

    2010-01-01

    The mechanism of air blast attenuation in a sacrificial cladding comprising a steel cover plate and a foam core is examined applying an analytical and numerical analysis. For the range of the analysed pressure pulses, the maximum magnitudes of the induced compaction velocities were usually smaller than the acoustic wave speed in the foam material and caused a non-uniform foam

  7. Vascular and Inflammatory Factors in the Pathophysiology of Blast-Induced Brain Injury

    PubMed Central

    Elder, Gregory A.; Gama Sosa, Miguel A.; De Gasperi, Rita; Stone, James Radford; Dickstein, Dara L.; Haghighi, Fatemeh; Hof, Patrick R.; Ahlers, Stephen T.

    2015-01-01

    Blast-related traumatic brain injury (TBI) has received much recent attention because of its frequency in the conflicts in Iraq and Afghanistan. This renewed interest has led to a rapid expansion of clinical and animal studies related to blast. In humans, high-level blast exposure is associated with a prominent hemorrhagic component. In animal models, blast exerts a variety of effects on the nervous system including vascular and inflammatory effects that can be seen with even low-level blast exposures which produce minimal or no neuronal pathology. Acutely, blast exposure in animals causes prominent vasospasm and decreased cerebral blood flow along with blood-brain barrier breakdown and increased vascular permeability. Besides direct effects on the central nervous system, evidence supports a role for a thoracically mediated effect of blast; whereby, pressure waves transmitted through the systemic circulation damage the brain. Chronically, a vascular pathology has been observed that is associated with alterations of the vascular extracellular matrix. Sustained microglial and astroglial reactions occur after blast exposure. Markers of a central and peripheral inflammatory response are found for sustained periods after blast injury and include elevation of inflammatory cytokines and other inflammatory mediators. At low levels of blast exposure, a microvascular pathology has been observed in the presence of an otherwise normal brain parenchyma, suggesting that the vasculature may be selectively vulnerable to blast injury. Chronic immune activation in brain following vascular injury may lead to neurobehavioral changes in the absence of direct neuronal pathology. Strategies aimed at preventing or reversing vascular damage or modulating the immune response may improve the chronic neuropsychiatric symptoms associated with blast-related TBI. PMID:25852632

  8. Dispersion Solver with Relativistic Cyclotron Resonance

    NASA Astrophysics Data System (ADS)

    Nakamura, T. K.

    2002-12-01

    A method to calculate linear dispersion relation of electromagnetic waves in a relativistic plasma is proposed. Exact analytic calculation with relativistic cyclotron resonances is extremely difficult because the cyclotron frequency depends on both parallel and perpendicular (to magnetic field) velocities due to the relativistic effect. To avoid this difficulty, the method presented here makes use of algebraic approximation to the velocity distribution function. Algebraic approximation enables analytical velocity integration with the residue theorem; results are highly accurate when applied to non-relativistic calculation (see references). The same tactics can be applied for relativistic plasmas, however, there comes a problem of branch cut and multiple Riemann surfaces. This problem must be overcome by ad hoc technique depending on each specific wave mode. Calculation for a parallel propagating electromagnetic wave in a relativistic plasma will be presented as an example. References: Lofgren et al., Phys. Plasmas, vol 4, 1124 (1997). Nakamura, T. K., and M. Hoshino, Phys. Plasmas, vol 5, 3547 (1998).

  9. Relativistic distorted-wave collision strengths and oscillator strengths for the 185 ?n = 0 transitions with n = 2 in the 67 C-like ions with 26 ? Z ? 92

    NASA Astrophysics Data System (ADS)

    Zhang, Hong Lin; Fontes, Christopher J.

    2015-01-01

    Relativistic distorted-wave collision strengths have been calculated for the 185 ?n = 0 transitions with n = 2 in the 67 C-like ions with nuclear charge number Z in the range 26 ? Z ? 92. The calculations were made for the six final, or scattered, electron energies E? = 0.03 , 0.08 , 0.20 , 0.42 , 0.80 , and 1.40, where E? is in units of Zeff2 Ry with Zeff = Z - 4.17. In addition, electric dipole oscillator strengths are provided. In the present collision-strength calculations, an improved "top-up" method, which employs relativistic plane waves, was used to obtain the high partial-wave contribution for each transition, in contrast to the partial-relativistic Coulomb-Bethe approximation used in previous work by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 63 (1996) 275]. In that earlier work, collision strengths were also provided for the same 185 ?n = 0 transitions in C-like ions, but for the more limited list of 46 ions with Z in the range 9 ? Z ? 54. The collision strengths covered in the present work, particularly those for optically allowed transitions, should be more accurate than the corresponding data given by Zhang and Sampson [H.L. Zhang, D.H. Sampson, At. Data Nucl. Data Tables 63 (1996) 275] and are presented here to replace those earlier results.

  10. 29 CFR 1926.912 - Underwater blasting.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...AND HEALTH REGULATIONS FOR CONSTRUCTION Blasting and the Use of Explosives § 1926.912 Underwater blasting. (a) A blaster shall conduct all blasting operations, and no shot shall be fired without his approval. (b) Loading tubes and...

  11. Recent advances on structural vibration control and blast resistance research in HIT Blast Resistance and Protective Engineering laboratory

    Microsoft Academic Search

    C. Zhang; H. Xu; J. Liu; L. Li; X. Zhang; C. Liu; Z. Wu; J. Li

    In this paper, several innovative control systems developed for the vibration control of civil engineering structures subjected to various environmental excitations (such as earthquake, wind load, ocean waves and ice etc.) are introduced, which have been studied by the Blast Resistance and Protective Engineering laboratory of Harbin Institute of Technology (HIT-BRPE) during the past several years. Firstly, the dynamics and

  12. Strong Ionizing Shock Waves

    Microsoft Academic Search

    Robert A. Gross

    1965-01-01

    The physical effects created by strong shock waves propagating in hydrogen are reviewed and theoretically studied for speeds up to relativistic conditions. In the progression from weak to relativistic shock speeds, various physical phenomena affect the shock wave. Dissociation, ionization, and the presence of an upstream electric field cause several important effects for slow (sub-Alfvénic speed) normal ionizing shock waves.

  13. Non linear particle acceleration at non-relativistic shock waves in the presence of self-generated turbulence

    E-print Network

    Elena Amato; Pasquale Blasi

    2006-06-23

    Particle acceleration at astrophysical shocks may be very efficient if magnetic scattering is self-generated by the same particles. This nonlinear process adds to the nonlinear modification of the shock due to the dynamical reaction of the accelerated particles on the shock. Building on a previous general solution of the problem of particle acceleration with arbitrary diffusion coefficients (Amato & Blasi, 2005), we present here the first semi-analytical calculation of particle acceleration with both effects taken into account at the same time: charged particles are accelerated in the background of Alfven waves that they generate due to the streaming instability, and modify the dynamics of the plasma in the shock vicinity.

  14. Scientific director`s report of atomic weapon tests at Eniwetok, 1951. Annex 1.6. Blast measurements, Part I. Summary report

    Microsoft Academic Search

    G. K. Hartmann; C. W. Lampson; C. J. Aronson

    1951-01-01

    Measurements of the blast pressures in Shots Dog, Easy, and George, together with earth-shock measurements on Shots Easy and George, gave new and important information concerning the magnitude and character of the blast wave near an atomic bomb. These experiments showed that secondary phenomena due presumably to thermal radiation and ion combination affect the pressure wave rather markedly near the

  15. Dynamic Theory of Relativistic Electrons Stochastic Heating by Whistler Mode Waves with Application to the Earth Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Tel'nikhin, A. A.; Kronberg, T. K.

    2007-01-01

    In the Hamiltonian approach an electron motion in a coherent packet of the whistler mode waves propagating along the direction of an ambient magnetic field is studied. The physical processes by which these particles are accelerated to high energy are established. Equations governing a particle motion were transformed in to a closed pair of nonlinear difference equations. The solutions of these equations have shown there exists the energetic threshold below that the electron motion is regular, and when the initial energy is above the threshold an electron moves stochastically. Particle energy spectra and pitch angle electron scattering are described by the Fokker-Planck-Kolmogorov equations. Calculating the stochastic diffusion of electrons due to a spectrum of whistler modes is presented. The parametric dependence of the diffusion coefficients on the plasma particle density, magnitude of wave field, and the strength of magnetic field is studies. It is shown that significant pitch angle diffusion occurs for the Earth radiation belt electrons with energies from a few keV up to a few MeV.

  16. GAMMA-RAY BURST DYNAMICS AND AFTERGLOW RADIATION FROM ADAPTIVE MESH REFINEMENT, SPECIAL RELATIVISTIC HYDRODYNAMIC SIMULATIONS

    SciTech Connect

    De Colle, Fabio; Ramirez-Ruiz, Enrico [Astronomy and Astrophysics Department, University of California, Santa Cruz, CA 95064 (United States); Granot, Jonathan [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Lopez-Camara, Diego, E-mail: fabio@ucolick.org [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ap. 70-543, 04510 D.F. (Mexico)

    2012-02-20

    We report on the development of Mezcal-SRHD, a new adaptive mesh refinement, special relativistic hydrodynamics (SRHD) code, developed with the aim of studying the highly relativistic flows in gamma-ray burst sources. The SRHD equations are solved using finite-volume conservative solvers, with second-order interpolation in space and time. The correct implementation of the algorithms is verified by one-dimensional (1D) and multi-dimensional tests. The code is then applied to study the propagation of 1D spherical impulsive blast waves expanding in a stratified medium with {rho}{proportional_to}r{sup -k}, bridging between the relativistic and Newtonian phases (which are described by the Blandford-McKee and Sedov-Taylor self-similar solutions, respectively), as well as to a two-dimensional (2D) cylindrically symmetric impulsive jet propagating in a constant density medium. It is shown that the deceleration to nonrelativistic speeds in one dimension occurs on scales significantly larger than the Sedov length. This transition is further delayed with respect to the Sedov length as the degree of stratification of the ambient medium is increased. This result, together with the scaling of position, Lorentz factor, and the shock velocity as a function of time and shock radius, is explained here using a simple analytical model based on energy conservation. The method used for calculating the afterglow radiation by post-processing the results of the simulations is described in detail. The light curves computed using the results of 1D numerical simulations during the relativistic stage correctly reproduce those calculated assuming the self-similar Blandford-McKee solution for the evolution of the flow. The jet dynamics from our 2D simulations and the resulting afterglow light curves, including the jet break, are in good agreement with those presented in previous works. Finally, we show how the details of the dynamics critically depend on properly resolving the structure of the relativistic flow.

  17. General Relativistic Hydrodynamics on Overlapping Curvilinear Grids

    E-print Network

    Blakely, P. M.; Nikiforakis, N.; Henshaw, W. D.

    2015-03-04

    - ably hope that propagation of numerical errors outside the event horizon will be limited. In general, however, note that numerical waves can propagate faster than any of the physical wave-speeds. This means that we can excise part of the domain inside... – hydrodynamics – shock waves 1. Introduction The simulation of general relativistic hydrodynamical (GRHD) problems is of great importance to the astrophysics commu- nity. Although special relativistic and post Newtonian approx- imations can be used in some cases...

  18. General Relativistic Self-Similar Waves that induce an Anomalous Acceleration into the Standard Model of Cosmology

    E-print Network

    Joel Smoller; Blake Temple

    2010-05-20

    We prove that the Einstein equations in Standard Schwarzschild Coordinates close to form a system of three ordinary differential equations for a family of spherically symmetric, self-similar expansion waves, and the critical ($k=0$) Friedmann universe associated with the pure radiation phase of the Standard Model of Cosmology (FRW), is embedded as a single point in this family. Removing a scaling law and imposing regularity at the center, we prove that the family reduces to an implicitly defined one parameter family of distinct spacetimes determined by the value of a new {\\it acceleration parameter} $a$, such that $a=1$ corresponds to FRW. We prove that all self-similar spacetimes in the family are distinct from the non-critical $k\

  19. ATOMIC AND MOLECULAR PHYSICS: Relativistic Distorted-Wave Collision Strengths of Ni-, Cu- and Zn-like Au Ions

    NASA Astrophysics Data System (ADS)

    Yang, Ning-Xuan; Dong, Chen-Zhong; Jiang, Jun

    2009-05-01

    Excitation energies and electron impact excitation strengths from the ground states of Ni-, Cu- and Zn-like Au ions are calculated. The collision strengths are computed by a 213-levels expansion for the Ni-like Au ion, 405-levels expansion for the Cu-like Au ion and 229-levels expansion for the Zn-like Au ion. Configuration interactions are taken into account for all levels included. The target state wavefunctions are calculated by using the Grasp92 code. The continuum orbits are computed in the distorted-wave approximation, in which the direct and exchange potentials among all the electrons are included. Excellent agreement is found when the results are compared with previous calculations and recent measurements.

  20. Dynamic Theory of Relativistic Electrons Stochastic Heating by Whistler Mode Waves with Application to the Earth Magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Tel'nikhin, A. A.; Kronberg, T. K.

    2006-01-01

    In the Hamiltonian approach an electron motion in a coherent packet of the whistler mode waves propagating along the direction of an ambient magnetic field is studied. The physical processes by which these particles are accelerated to high energy are established. Equations governing a particle motion by group symmetries of the problem were transformed in to a closed pair of nonlinear difference equations. The solutions of these equations have shown there exists the energetic threshold below that the electron motion is regular, and when the initial energy is above the threshold an electron moves stochastically. It is proved that the upper boundary of particle stochastic heating is conditioned by intrinsic property of the particle chaotic motion. Particle energy spectra and pitch angle electron scattering are described by the Fokker-Planck-Kolmogorov equations. It is shown that significant pitch angle diffusion occurs for the Earth radiation belt electrons with energies from a few keV up to a few MeV.

  1. Fast Lattice Boltzmann Solver for Relativistic Hydrodynamics

    SciTech Connect

    Mendoza, M.; Herrmann, H. J. [ETH Zuerich, Computational Physics for Engineering Materials, Institute for Building Materials, Schafmattstrasse 6, HIF, CH-8093 Zuerich (Switzerland); Boghosian, B. M. [Department of Mathematics, Tufts University, Bromfield-Pearson, Medford, Massachusetts 02155 (United States); Succi, S. [Istituto per le Applicazioni del Calcolo C.N.R., Via dei Taurini, 19 00185, Rome (Italy) and Freiburg Institute for Advanced Studies, Albertstrasse, 19, D-79104, Freiburg (Germany)

    2010-07-02

    A lattice Boltzmann formulation for relativistic fluids is presented and numerically validated through quantitative comparison with recent hydrodynamic simulations of relativistic fluids. In order to illustrate its capability to handle complex geometries, the scheme is also applied to the case of a three-dimensional relativistic shock wave, generated by a supernova explosion, impacting on a massive interstellar cloud. This formulation opens up the possibility of exporting the proven advantages of lattice Boltzmann methods, namely, computational efficiency and easy handling of complex geometries, to the context of (mildly) relativistic fluid dynamics at large, from quark-gluon plasmas up to supernovae with relativistic outflows.

  2. Fast lattice Boltzmann solver for relativistic hydrodynamics.

    PubMed

    Mendoza, M; Boghosian, B M; Herrmann, H J; Succi, S

    2010-07-01

    A lattice Boltzmann formulation for relativistic fluids is presented and numerically validated through quantitative comparison with recent hydrodynamic simulations of relativistic fluids. In order to illustrate its capability to handle complex geometries, the scheme is also applied to the case of a three-dimensional relativistic shock wave, generated by a supernova explosion, impacting on a massive interstellar cloud. This formulation opens up the possibility of exporting the proven advantages of lattice Boltzmann methods, namely, computational efficiency and easy handling of complex geometries, to the context of (mildly) relativistic fluid dynamics at large, from quark-gluon plasmas up to supernovae with relativistic outflows. PMID:20867451

  3. Shock wave interaction with interfaces between materials having different acoustic impedances

    NASA Astrophysics Data System (ADS)

    Hosseini, H.; Moosavi-Nejad, S.; Akiyama, H.; Menezes, V.

    2014-03-01

    We experimentally examined interaction of blast waves with water-air/air-water interfaces through high-speed-real-time visualization and measurement of pressure across the waves. The underwater shock wave, which was expected to reflect totally at the water-air interface, was observed transmitting a shock front to air. Transmission of a blast wave from air to water was also visualized and evaluated. Underwater shock waves are used in several medical/biological procedures, where such unforeseen transmissions can result in detriments. The details provide a guideline to evaluate blast wave transmissions, which can induce tissue and brain injuries. The results explain mechanisms behind blast-induced traumatic brain injury.

  4. Coronal Shock Waves, EUV Waves, and Their Relation to CMEs. I. Reconciliation of

    Microsoft Academic Search

    V. V. Grechnev; A. M. Uralov; I. M. Chertok; I. V. Kuzmenko; A. N. Afanasyev; N. S. Meshalkina; S. S. Kalashnikov; Y. Kubo

    2011-01-01

    We show examples of the excitation of coronal waves by flare-related abrupt eruptions of magnetic rope structures. The waves presumably rapidly steepened into shocks and freely propagated afterwards like decelerating blast waves that showed up as Moreton waves and EUV waves. We propose a simple quantitative description for such shock waves to reconcile their observed propagation with drift rates of

  5. Relativistic diffusion

    Microsoft Academic Search

    Z. Haba

    2009-01-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic

  6. Relativistic diffusion

    E-print Network

    Haba, Z

    2008-01-01

    We define a relativistic diffusion equation on the phase space. We consider stochastic Ito (Langevin) differential equation on the phase space as a perturbation by noise of relativistic dynamics. The motion in an electromagnetic field is treated as an example. Transport equations and equilibrium probability distributions are investigated. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  7. The BLAST experiment

    Microsoft Academic Search

    D. Hasell; T. Akdogan; R. Alarcon; W. Bertozzi; E. Booth; T. Botto; J. R. Calarco; B. Clasie; C. Crawford; A. Degrush; K. Dow; D. Dutta; M. Farkhondeh; R. Fatemi; O. Filoti; W. Franklin; H. Gao; E. Geis; S. Gilad; W. Hersman; M. Holtrop; E. Ihloff; P. Karpius; J. Kelsey; M. Kohl; H. Kolster; S. Krause; T. Lee; A. Maschinot; J. Matthews; K. McIlhany; N. Meitanis; R. Milner; J. Rapaport; R. Redwine; J. Seely; A. Sindile; S. Širca; T. Smith; S. Sobczynski; M. Tanguay; B. Tonguc; C. Tschalaer; E. Tsentalovich; W. Turchinetz; J. van der Laan; F. Wang; T. Wise; Y. Xiao; W. Xu; C. Zhang; Z. Zhou; V. Ziskin; T. Zwart

    2009-01-01

    The Bates large acceptance spectrometer toroid (BLAST) experiment was operated at the MIT-Bates Linear Accelerator Center from 2003 until 2005. The detector and experimental program were designed to study, in a systematic manner, the spin-dependent electromagnetic interaction in few-nucleon systems. As such the data will provide improved measurements for neutron, proton, and deuteron form factors. The data will also allow

  8. Waves

    NSDL National Science Digital Library

    Mr. Hansen

    2010-11-12

    The following websites are useful tools in understanding how energy is transferred from place to place through waves. Start by downloading the assignment and then begin with website number 1 and continue until you have visited all three websites. Begin by downloading the IA Waves Internet Assignment: IA Waves Internet Assignment You will answer the questions in Microsoft Word and then e-mail the assignment to me. Website #1: Read about basic information on waves and answer the questions from part 1 of the IA Waves Guide: Basic Wave Information Website #2: Follow the instructions for the following ...

  9. Concepts of blast hole pressure applied to blast design

    Microsoft Academic Search

    C. Cunningham

    2006-01-01

    Blast hole pressure is the starting point for many blast design calculations, but the way in which it is usually derived, from measured detonation velocity, indicates that more thought is needed as to its true meaning and implication. The general impression is given that the energy in the hole is defined by velocity of detonation (VoD), but this is rarely

  10. Identification of blast resistance genes for managing rice blast disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases worldwide. In the present study, an international set of monogenic differentials carrying 24 major blast resistance (R) genes (Pia, Pib, Pii, Pik, Pik-h, Pik-m, Pik-p, Pik-s, Pish, Pit, Pita, Pita2,...

  11. Characterization of the response to primary blast injury.

    PubMed

    Kirkman, E; Watts, S

    2011-01-27

    Lung injuries, predominantly arising from blast exposure, are a clinical problem in a significant minority of current military casualties. This special feature consists of a series of articles on lung injury. This first article examines the mechanism of the response to blast lung (primary blast injury to the lung). Subsequent articles examine the incidence of blast lung, clinical consequences and current concepts of treatment, computer (in silico) modelling of lung injury and finally chemical injuries to the lungs. Blast lung is caused by a shock wave generated by an explosion causing widespread damage in the lungs, leading to intrapulmonary haemorrhage. This, and the ensuing inflammatory response in the lung, leads to a compromise in pulmonary gas exchange and hypoxia that can worsen over several hours. There is also a characteristic cardio-respiratory effect mediated via an autonomic reflex causing apnoea (or rapid shallow breathing), bradycardia and hypotension (the latter possibly also due to the release of nitric oxide). An understanding of this response, and the way it modifies other reflexes, can help the development of new treatment strategies for this condition and for the way it influences the patient's response to concomitant injuries. PMID:21149364

  12. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    SciTech Connect

    Dr. M.A. Ebadian

    2000-01-13

    The purpose of the project is to increase the productivity and economics of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCB's and lead-base paint and provides worker and environmental protection by continuously recycling the blast media and the full containment of the dust generated in the process.

  13. Dynamic properties of blast furnaces

    Microsoft Academic Search

    V. I. Naboka; G. A. Polyanskii; A. P. Fomenko; N. V. Krutas

    2008-01-01

    In the present work, we investigate the dynamic properties of the blast-furnace process in terms of the two control signals (change in the ore load and change in the blast parameters), as well as random perturbing signals that change the composition of the furnace gas as a function of the ratio of direct and indirect ferrousoxide (FeO) reduction and the

  14. Imbalanced relativistic force-free magnetohydrodynamic turbulence

    SciTech Connect

    Cho, Jungyeon [Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of); Lazarian, A., E-mail: jcho@cnu.ac.kr [Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States)

    2014-01-01

    When magnetic energy density is much larger than that of matter, as in pulsar/black hole magnetospheres, the medium becomes force-free and we need relativity to describe it. As in non-relativistic magnetohydrodynamics (MHD), Alfvénic MHD turbulence in the relativistic limit can be described by interactions of counter-traveling wave packets. In this paper, we numerically study strong imbalanced MHD turbulence in such environments. Here, imbalanced turbulence means the waves traveling in one direction (dominant waves) have higher amplitudes than the opposite-traveling waves (sub-dominant waves). We find that (1) spectrum of the dominant waves is steeper than that of sub-dominant waves, (2) the anisotropy of the dominant waves is weaker than that of sub-dominant waves, and (3) the dependence of the ratio of magnetic energy densities of dominant and sub-dominant waves on the ratio of energy injection rates is steeper than quadratic (i.e., b{sub +}{sup 2}/b{sub ?}{sup 2}?(?{sub +}/?{sub ?}){sup n} with n > 2). These results are consistent with those obtained for imbalanced non-relativistic Alfvénic turbulence. This corresponds well to the earlier reported similarity of the relativistic and non-relativistic balanced magnetic turbulence.

  15. Computer Simulation of Blast Wall Protection under Methane-Air Explosion on an Offshore Platform

    NASA Astrophysics Data System (ADS)

    Wang, Changjian; Yan, Weigang; Guo, Jin; Guo, Changming

    An in-house explosion program is presented to evaluate blast wall protection under Methane-Air Explosion on an offshore platform, based on two-dimensional, time-dependent, reactive Navier-Stokes equations including the effects of viscosity, thermal conduction and molecular diffusion. The results show that this program can successfully produce explosion process of methane-air gas cloud. Because the overpressure behind the blast wall and on the lifeboat plate is more than 1.0atm when explosion wave passes, the current blast wall is not enough to keep the person and lifeboat safe. So the blast wall needs to be re-designed. The explosion wave of methane-air gas cloud undergoes a successive process of detonation formation, detonation transmission, shock attenuation, regular reflection and Mach reflection etc. Additionally, due to high overpressure generated in gas cloud explosion, it is extremely devastating and must be avoided at all times on offshore platform.

  16. Mechanics of blast loading on the head models in the study of traumatic brain injury using experimental and computational approaches.

    PubMed

    Ganpule, S; Alai, A; Plougonven, E; Chandra, N

    2013-06-01

    Blast waves generated by improvised explosive devices can cause mild, moderate to severe traumatic brain injury in soldiers and civilians. To understand the interactions of blast waves on the head and brain and to identify the mechanisms of injury, compression-driven air shock tubes are extensively used in laboratory settings to simulate the field conditions. The overall goal of this effort is to understand the mechanics of blast wave-head interactions as the blast wave traverses the head/brain continuum. Toward this goal, surrogate head model is subjected to well-controlled blast wave profile in the shock tube environment, and the results are analyzed using combined experimental and numerical approaches. The validated numerical models are then used to investigate the spatiotemporal distribution of stresses and pressure in the human skull and brain. By detailing the results from a series of careful experiments and numerical simulations, this paper demonstrates that: (1) Geometry of the head governs the flow dynamics around the head which in turn determines the net mechanical load on the head. (2) Biomechanical loading of the brain is governed by direct wave transmission, structural deformations, and wave reflections from tissue-material interfaces. (3) Deformation and stress analysis of the skull and brain show that skull flexure and tissue cavitation are possible mechanisms of blast-induced traumatic brain injury. PMID:22832705

  17. Development of Experimental Tissue Models for Blast Injury

    NASA Astrophysics Data System (ADS)

    Butler, Benjamin; Bo, Chiara; Williams, Alun; Jardine, Andy; Brown, Katherine

    2013-06-01

    There is a pressing need to better understand the relationship between the intensity of a blast wave and the clinical consequences for victims of an explosion. In order to quantitatively study how these factors correlate with one another, blast injury tissue models are being developed. Sections of larynx, trachea and pulmonary tissue were excised from a recently sacrificed pig and maintained on ice prior to testing. The samples were subjected to strain rates of between 0.001 s-1 and 1000 s-1 in the laboratory by using a Split Hopkinson Pressure Bar and quasi-static testing apparatus. During high strain rate testing, samples were housed in a polycarbonate chamber which permitted experimentation on tissue held in fluid. Data were analysed using 1, 2 and 3 wave analysis software in Matlab to yield information about the material properties of both undamaged and damaged tissues. In addition, macroscopic changes in tissue organization were also visualized using histopathological techniques. This work is being extended to cellular and animal models to derive more detailed information about the underlying molecular changes relating to blast-induced damage and repair. There is a pressing need to better understand the relationship between the intensity of a blast wave and the clinical consequences for victims of an explosion. In order to quantitatively study how these factors correlate with one another, blast injury tissue models are being developed. Sections of larynx, trachea and pulmonary tissue were excised from a recently sacrificed pig and maintained on ice prior to testing. The samples were subjected to strain rates of between 0.001 s-1 and 1000 s-1 in the laboratory by using a Split Hopkinson Pressure Bar and quasi-static testing apparatus. During high strain rate testing, samples were housed in a polycarbonate chamber which permitted experimentation on tissue held in fluid. Data were analysed using 1, 2 and 3 wave analysis software in Matlab to yield information about the material properties of both undamaged and damaged tissues. In addition, macroscopic changes in tissue organization were also visualized using histopathological techniques. This work is being extended to cellular and animal models to derive more detailed information about the underlying molecular changes relating to blast-induced damage and repair. The Royal British Legion Centre for Blast Injury Studies.

  18. Computer assisted blast design and assessment tools

    SciTech Connect

    Cameron, A.R. [Golder Associates Ltd., Sudbury, Ontario (Canada); Kleine, T.H. [Golder Associates Inc., Seattle, WA (United States); Forsyth, W.W. [Golder Associates Ltd., Vancouver, British Columbia (Canada)

    1995-12-31

    In general the software required by a blast designer includes tools that graphically present blast designs (surface and underground), can analyze a design or predict its result, and can assess blasting results. As computers develop and computer literacy continues to rise the development of and use of such tools will spread. An example of the tools that are becoming available includes: Automatic blast pattern generation and underground ring design; blast design evaluation in terms of explosive distribution and detonation simulation; fragmentation prediction; blast vibration prediction and minimization; blast monitoring for assessment of dynamic performance; vibration measurement, display and signal processing; evaluation of blast results in terms of fragmentation; and risk and reliability based blast assessment. The authors have identified a set of criteria that are essential in choosing appropriate software blasting tools.

  19. Relativistic astrometry

    NASA Astrophysics Data System (ADS)

    Kopeikin, Sergei

    2011-07-01

    Relativistic astrometry studies the geometric relationships between astronomical objects in warped spacetime of the Universe by making use of high-precision astrometric techniques: optical space interferometry, very-long baseline interferometry (VLBI), pulsar timing, atomic clocks. It is based on the physical principles of Einstein's general theory of relativity and utilizes a powerful mathematical apparatus of differential geometry. Applied relativistic astrometry uses general-relativistic algorithms for processing high-precision astrometric data for building the fundamental catalog of stars and extra-galactic sources - quasars which establishes the inertial reference frame in the sky. Experimental relativistic astrometry explores the existence of presumable deviations from the general theory of relativity predicted by valid alternative theories of gravity.

  20. 6/2/12 NCBI Blast:sbe vs human 1/770www.ncbi.nlm.nih.gov/blast/Blast.cgi

    E-print Network

    Hickman, Mark

    6/2/12 NCBI Blast:sbe vs human 1/770www.ncbi.nlm.nih.gov/blast/Blast.cgi Database Name Description Blast:sbe vs human 2/770www.ncbi.nlm.nih.gov/blast/Blast.cgi Legend for links to other resources: Uni

  1. 129 Lecture Notes Relativistic Quantum Mechanics

    E-print Network

    Murayama, Hitoshi

    129 Lecture Notes Relativistic Quantum Mechanics 1 Need for Relativistic Quantum Mechanics the single-particle Schr¨odinger wave equation, but obtained only by going to quantum field theory. We's equation of motion in mechanics. The initial condtions to solve the Newton's equation of motion

  2. 221B Lecture Notes Relativistic Quantum Mechanics

    E-print Network

    Murayama, Hitoshi

    221B Lecture Notes Relativistic Quantum Mechanics 1 Need for Relativistic Quantum Mechanics We the single-particle Schr¨odinger wave equation, but obtained only by going to quantum field theory. We's equation of motion in mechanics. The initial condtions to solve the Newton's equation of motion

  3. 221B Lecture Notes Relativistic Quantum Mechanics

    E-print Network

    Murayama, Hitoshi

    221B Lecture Notes Relativistic Quantum Mechanics 1 Need for Relativistic Quantum Mechanics We the single-particle Schr¨odinger wave equation, but obtained only by going to quantum field theory. We, similarly to the Newton's equation of motion in mechanics. The initial condtions to solve the Newton

  4. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    SciTech Connect

    William S. McPhee

    1999-05-31

    The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and construct a pre-prototype of the nozzle, blast head with wind curtain, sensors, and dust separator and test this system to assess the performance of the new design under controlled conditions at the contractor's facility. In phase III, the Contractor shall design and construct a prototype of the High Productivity Vacuum Blasting System, based on the results of the pre-prototype design and testing performed. This unit will be a full-scale prototype and will be tested at a designated Department of Energy (DOE) facility. Based on the results, the system performance, the productivity, and the economy of the improved vacuum blasting system will be evaluated.

  5. Modeling clinically relevant blast parameters based on scaling principles produces functional & histological deficits in rats.

    PubMed

    Turner, Ryan C; Naser, Zachary J; Logsdon, Aric F; DiPasquale, Kenneth H; Jackson, Garrett J; Robson, Matthew J; Gettens, Robert T T; Matsumoto, Rae R; Huber, Jason D; Rosen, Charles L

    2013-10-01

    Blast-induced traumatic brain injury represents a leading cause of injury in modern warfare with injury pathogenesis poorly understood. Preclinical models of blast injury remain poorly standardized across laboratories and the clinical relevance unclear based upon pulmonary injury scaling laws. Models capable of high peak overpressures and of short duration may better replicate clinical exposure when scaling principles are considered. In this work we demonstrate a tabletop shock tube model capable of high peak overpressures and of short duration. By varying the thickness of the polyester membrane, peak overpressure can be controlled. We used membranes with a thickness of 0.003, 0.005, 0.007, and 0.010 in to generate peak reflected overpressures of 31.47, 50.72, 72.05, and 90.10 PSI, respectively. Blast exposure was shown to decrease total activity and produce neural degeneration as indicated by fluoro-jade B staining. Similarly, blast exposure resulted in increased glial activation as indicated by an increase in the number of glial fibrillary acidic protein expressing astrocytes compared to control within the corpus callosum, the region of greatest apparent injury following blast exposure. Similar findings were observed with regard to activated microglia, some of which displayed phagocytic-like morphology within the corpus callosum following blast exposure, particularly with higher peak overpressures. Furthermore, hematoxylin and eosin staining showed the presence of red blood cells within the parenchyma and red, swollen neurons following blast injury. Exposure to blast with 90.10 PSI peak reflected overpressure resulted in immediate mortality associated with extensive intracranial bleeding. This work demonstrates one of the first examples of blast-induced brain injury in the rodent when exposed to a blast wave scaled from human exposure based on scaling principles derived from pulmonary injury lethality curves. PMID:23876514

  6. Octonic relativistic quantum mechanics

    E-print Network

    V. L. Mironov; S. V. Mironov

    2008-04-22

    In this paper we represent the generalization of relativistic quantum mechanics on the base of eght-component values "octons", generating associative noncommutative spatial algebra. It is shown that the octonic second-order equation for the eight-component octonic wave function, obtained from the Einshtein relation for energy and momentum, describes particles with spin of 1/2. It is established that the octonic wave function of a particle in the state with defined spin projection has the specific spatial structure in the form of octonic oscillator with two spatial polarizations: longitudinal linear and transversal circular. The relations between bispinor and octonic descriptions of relativistic particles are established. We propose the eight-component spinors, which are octonic generalisation of two-component Pauli spinors and four-component Dirac bispinors. It is shown that proposed eight-component spinors separate the states with different spin projection, different particle-antiparticle state as well as different polarization of the octonic oscillator. We demonstrate that in the frames of octonic relativistic quantum mechanics the second-order equation for octonic wave function can be reformulated in the form of the system of first-order equations for quantum fields, which is analogous to the system of Maxwell equations for the electromagnetic field. It is established that for the special type of wave functions the second-order equation can be reduced to the single first-order equation, which is analogous to the Dirac equation. At the same time it is shown that this first-order equation describes particles, which do not create quantum fields.

  7. Centrifugal shot blast system

    SciTech Connect

    NONE

    1998-02-01

    This report describes a demonstration of Concrete cleaning, Inc., modified centrifugal shot blast technology to remove the paint coating from concrete flooring. This demonstration is part of the Chicago Pile-5 (CP-5) Large-Scale Demonstration Project (LSDP) sponsored by the US Department of Energy (DOE), office of Science and Technology (OST), Deactivation and Decommissioning Focus Area (DDFA). The objective of the LSDP is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) CP-5 Research Reactor. The purpose of the LSDP is to demonstrate that using innovative and improved decontamination and decommissioning (D and D) technologies from various sources can result in significant benefits, such as decreased cost and increased health and safety, as compared with baseline D and D technologies. Potential markets exist for the innovative centrifugal shot blast system at the following sites: Fernald Environmental Management Project, Los Alamos, Nevada, Oak Ridge Y-12 and K-25, Paducah, Portsmouth Gaseous Diffusion site, and the Savannah River Site. This information is based on a revision to the OST Linkage Tables dated August 4, 1997.

  8. GEOPHYSICS, \\`OL. 34. ti0. 5 (OCTOBER 1060). P. 696-712, 16 FIGS. DYNAMIC PHOTOELASTIC STUDIES OF P AND S WAVE

    E-print Network

    Stewart, Sarah T.

    nuclear bomb blasts has been reported by several investigators. In order to further understanding of anomalous horizontally polar- ized seismic waves (SH and Love) from under- ground nuclear bomb blasts has

  9. Blasting casting to raise productivity

    SciTech Connect

    Pilshaw, S.R.

    1987-07-01

    Normally, surface mines employ draglines or truck and shovel systems to remove overburden. Blasting merely fragments and displaces the overburden enough to allow for easy digging. But during the past two decades, the effect of inflation and increased labor costs have encouraged unconventional methods of overburden removal. All of us are aware of the tremendous inflationary effects on costs of equipment, fuel, labor, interest, insurance, environmental compliance, etc. This has allowed the authors to take a new look at the use of explosives as an effective alternate method of overburden removal. This technique is known by several names, but basically blast casting or just casting best describes it. Other terms in vogue are explosive casting, controlled trajectory blasting, trajectory control blasting, and whatever terminology comes to mind.

  10. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler,; Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

    2010-10-26

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  11. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

    2007-05-22

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  12. Waves

    E-print Network

    LaCure, Mari Mae

    2010-04-29

    travel as waves through space and time. Waves can also manifest visibly through other mediums, water for example, as they travel outward from where an object disturbs the surface. As the title of my thesis exhibit, Waves refers to my aim to imbue.... As a viewer approaches a drawing from different angles the light reflected by the image subtly changes intensity. 4 Sewing by hand further adds dimension where it is seen in the front, and creates a shadow where it can be seen through the back...

  13. Blast Testing Issues and TBI: Experimental Models That Lead to Wrong Conclusions

    PubMed Central

    Needham, Charles E.; Ritzel, David; Rule, Gregory T.; Wiri, Suthee; Young, Leanne

    2015-01-01

    Over the past several years, we have noticed an increase in the number of blast injury studies published in peer-reviewed biomedical journals that have utilized improperly conceived experiments. Data from these studies will lead to false conclusions and more confusion than advancement in the understanding of blast injury, particularly blast neurotrauma. Computational methods to properly characterize the blast environment have been available for decades. These methods, combined with a basic understanding of blast wave phenomena, enable researchers to extract useful information from well-documented experiments. This basic understanding must include the differences and interrelationships of static pressure, dynamic pressure, reflected pressure, and total or stagnation pressure in transient shockwave flows, how they relate to loading of objects, and how they are properly measured. However, it is critical that the research community effectively overcomes the confusion that has been compounded by a misunderstanding of the differences between the loading produced by a free field explosive blast and loading produced by a conventional shock tube. The principles of blast scaling have been well established for decades and when properly applied will do much to repair these problems. This paper provides guidance regarding proper experimental methods and offers insights into the implications of improperly designed and executed tests. Through application of computational methods, useful data can be extracted from well-documented historical tests, and future work can be conducted in a way to maximize the effectiveness and use of valuable biological test data. PMID:25904891

  14. Numerical study of blast characteristics from detonation of homogeneous explosives

    Microsoft Academic Search

    Kaushik Balakrishnan; Franklin Genin; Doug V. Nance; Suresh Menon

    2010-01-01

    A new robust numerical methodology is used to investigate the propagation of blast waves from homogeneous explosives. The\\u000a gas-phase governing equations are solved using a hybrid solver that combines a higher-order shock capturing scheme with a\\u000a low-dissipation central scheme. Explosives of interest include Nitromethane, Trinitrotoluene, and High-Melting Explosive.\\u000a The shock overpressure and total impulse are estimated at different radial locations

  15. Blast From the Past

    NSDL National Science Digital Library

    A recently recovered deep-sea core supports theories that an asteroid collided with the earth 65 million years ago, around the time of the extinction of the dinosaurs. The Smithsonian Institution National Museum of Natural History's new site, Blast from the Past, contains details on this cataclysmic event. Colorful graphics provide conceptual illustrations of the asteroid impact and aftermath, accompanied by photographs of the deep-sea core. Text summaries, followed by bibliographic references, describe the asteroid hypothesis, the Cretaceous/Tertiary (K/T) boundary, and the utility of deep-sea cores. With links to other paleobiological sites and related museum exhibits, this site is a useful resource for those wanting to know more about fateful asteroid impacts.

  16. The BLAST experiment

    NASA Astrophysics Data System (ADS)

    Hasell, D.; Akdogan, T.; Alarcon, R.; Bertozzi, W.; Booth, E.; Botto, T.; Calarco, J. R.; Clasie, B.; Crawford, C.; DeGrush, A.; Dow, K.; Dutta, D.; Farkhondeh, M.; Fatemi, R.; Filoti, O.; Franklin, W.; Gao, H.; Geis, E.; Gilad, S.; Hersman, W.; Holtrop, M.; Ihloff, E.; Karpius, P.; Kelsey, J.; Kohl, M.; Kolster, H.; Krause, S.; Lee, T.; Maschinot, A.; Matthews, J.; McIlhany, K.; Meitanis, N.; Milner, R.; Rapaport, J.; Redwine, R.; Seely, J.; Shinozaki, A.; Sindile, A.; Širca, S.; Smith, T.; Sobczynski, S.; Tanguay, M.; Tonguc, B.; Tschalaer, C.; Tsentalovich, E.; Turchinetz, W.; van den Brand, J. F. J.; van der Laan, J.; Wang, F.; Wise, T.; Xiao, Y.; Xu, W.; Zhang, C.; Zhou, Z.; Ziskin, V.; Zwart, T.

    2009-05-01

    The Bates large acceptance spectrometer toroid (BLAST) experiment was operated at the MIT-Bates Linear Accelerator Center from 2003 until 2005. The detector and experimental program were designed to study, in a systematic manner, the spin-dependent electromagnetic interaction in few-nucleon systems. As such the data will provide improved measurements for neutron, proton, and deuteron form factors. The data will also allow details of the reaction mechanism, such as the role of final state interactions, pion production, and resonances to be studied. The experiment used: a longitudinally polarized electron beam stored in the South Hall Storage Ring; a highly polarized, isotopically pure, internal gas target of hydrogen or deuterium provided by an atomic beam source; and a symmetric, general purpose detector based on a toroidal spectrometer with tracking, time-of-flight, Cherenkov, and neutron detectors. Details of the experiment and operation are presented.

  17. Relativistic diffusion.

    PubMed

    Haba, Z

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed. PMID:19391727

  18. Relativistic diffusion

    E-print Network

    Z. Haba

    2009-02-26

    We discuss a relativistic diffusion in the proper time in an approach of Schay and Dudley. We derive (Langevin) stochastic differential equations in various coordinates.We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form.We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution.We discuss drag terms leading to an equilibrium distribution.The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Juettner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  19. Relativistic Thermodynamics

    NASA Astrophysics Data System (ADS)

    Hayward, Sean A.

    2013-03-01

    A generally relativistic theory of thermodynamics is developed, based on four main physical principles: heat is a local form of energy, therefore described by a thermal energy tensor; conservation of mass, equivalent to conservation of heat, or the local first law; entropy is a local current; and non-destruction of entropy, or the local second law. A fluid is defined by the thermostatic energy tensor being isotropic. The entropy current is related to the other fields by certain equations, including a generalized Gibbs equation for the thermostatic entropy, followed by linear and quadratic terms in the dissipative (thermal minus thermostatic) energy tensor. Then the second law suggests certain equations for the dissipative energy tensor, generalizing the Israel-Stewart dissipative relations, which describe heat conduction and viscosity including relativistic effects and relaxation effects. In the thermostatic case, the perfect-fluid model is recovered. In the linear approximation for entropy, the Eckart theory is recovered. In the quadratic approximation for entropy, the theory is similar to that of Israel and Stewart, but involving neither state-space differentials, nor a non-equilibrium Gibbs equation, nor nonmaterial frames. Also, unlike conventional thermodynamics, the thermal energy density is not assumed to be purely thermostatic, though this is derived in the linear approximation. Otherwise, the theory reduces in the non-relativistic limit to the extended thermodynamics of irreversible processes due to Müller. The dissipative energy density seems to be a new thermodynamical field, but also exists in relativistic kinetic theory of gases.

  20. Relativistic diffusion

    NASA Astrophysics Data System (ADS)

    Haba, Z.

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.