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Sample records for hypervelocity metal jets

  1. High-resolution imaging of hypervelocity metal jets using advanced high-speed photographic techniques

    SciTech Connect

    Shaw, L.L.; Muelder, S.A.

    1995-08-29

    It is now possible to obtain high resolution sequential photographs of the initial formation and evolution of hypervelocity metal jets formed by shaped charge devices fired in air. Researchers have been frustrated by the high velocity of the jet material and the luminous sheath of hot gases cloaking the jet that made detailed observation of the jet body extremely difficult. The camera system that provides the photographs is a large format multi-frame electro-optic camera, referred to as an IC camera (IC stands for image converter), that utilizes electro-optic shuttering, monochromatic pulsed laser illumination and bandpass filtering to provide sequential pictures (in 3D if desired) with minimal degradation due to luminous air shocks or motion blur. The large format (75mm image plane), short exposure (15 ns minimum), ruby laser illumination and bandpass filtering (monochromatic illumination while excluding extraneous light) produces clear, sharp, images of the detailed surface structure of a metal shaped charge jet during early jet formation, elongation of the jet body, jet tip evolution and subsequent particulation (breakup) of the jet body. By utilizing the new camera system in conjunction with the more traditional rotating mirror high speed cameras, pulsed radiography, and electrical sensors, a maximum amount of, often unique, data can be extracted from a single experiment. This paper was intended primarily as an oral presentation. For purposes of continuity and simplicity in these proceedings, the authors have chosen to concentrate on the development of the IC camera system and its impact on the photography of high speed shaped chargejets.

  2. Dense Hypervelocity Plasma Jets

    NASA Astrophysics Data System (ADS)

    Case, Andrew; Witherspoon, F. Douglas; Messer, Sarah; Bomgardner, Richard; Phillips, Michael; van Doren, David; Elton, Raymond; Uzun-Kaymak, Ilker

    2007-11-01

    We are developing high velocity dense plasma jets for fusion and HEDP applications. Traditional coaxial plasma accelerators suffer from the blow-by instability which limits the mass accelerated to high velocity. In the current design blow-by is delayed by a combination of electrode shaping and use of a tailored plasma armature created by injection of a high density plasma at a few eV generated by arrays of capillary discharges or sparkgaps. Experimental data will be presented for a complete 32 injector gun system built for driving rotation in the Maryland MCX experiment, including data on penetration of the plasma jet through a magnetic field. We present spectroscopic measurements of plasma velocity, temperature, and density, as well as total momentum measured using a ballistic pendulum. Measurements are in agreement with each other and with time of flight data from photodiodes and a multichannel PMT. Plasma density is above 10^15 cm-3, velocities range up to about 100 km/s. Preliminary results from a quadrature heterodyne HeNe interferometer are consistent with these results.

  3. Dense Hypervelocity Plasma Jets

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. Douglas; Case, Andrew; Phillips, Michael W.

    2006-10-01

    High velocity dense plasma jets are under continued experimental development for a variety of fusion applications including refueling, disruption mitigation, rotation drive, and magnetized target fusion. The technical goal is to accelerate plasma slugs of density >10^17 cm-3 and total mass >100 micrograms to velocities >200 km/s. The approach utilizes symmetrical injection of very high density plasma into a coaxial EM accelerator having a tailored cross-section geometry to prevent formation of the blow-by instability. Injected plasma is generated by electrothermal capillary discharges using either cylindrical capillaries or a newer toroidal spark gap arrangement that has worked at pressures as low as 3.5 x10-6 Torr in bench tests. Experimental plasma data will be presented for a complete 32 injector accelerator system recently built for driving rotation in the Maryland MCX experiment which utilizes the cylindrical capillaries, and also for a 50 spark gap test unit currently under construction.

  4. Dense Hypervelocity Plasma Jets for Fusion Applications

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. Douglas; Thio, Y. C. Francis

    2005-10-01

    High velocity dense plasma jets are being developed for a variety of fusion applications, including refueling, disruption mitigation, High Energy Density Plasmas, magnetized target/magneto-inertial fusion, injection of angular momentum into centrifugally confined mirrors, and others. The technical goal is to accelerate plasma blobs of density >10^17 cm-3 and total mass >100 micrograms to velocities >200 km/s. The approach utilizes symmetrical injection of very high density plasma into a coaxial EM accelerator having a tailored cross-section that prevents formation of the blow-by instability. AFRL MACH2 modeling identified 2 electrode configurations that produce the desired plasma jet parameters. The injected plasma is generated by up to 64 radially oriented capillary discharges arranged uniformly around the circumference of an angled annular injection section. Initial experimental results are presented in which 8 capillaries are fired in parallel with jitter of ˜100 ns. Current focus is on higher voltage operation to reduce jitter to a few 10's of ns, and development of a suite of optical and spectroscopic plasma diagnostics.

  5. Hypervelocity Impact Evaluation of Metal Foam Core Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Yasensky, John; Christiansen, Eric L.

    2007-01-01

    A series of hypervelocity impact (HVI) tests were conducted by the NASA Johnson Space Center (JSC) Hypervelocity Impact Technology Facility (HITF) [1], building 267 (Houston, Texas) between January 2003 and December 2005 to test the HVI performance of metal foams, as compared to the metal honeycomb panels currently in service. The HITF testing was conducted at the NASA JSC White Sands Testing Facility (WSTF) at Las Cruces, New Mexico. Eric L. Christiansen, Ph.D., and NASA Lead for Micro-Meteoroid Orbital Debris (MMOD) Protection requested these hypervelocity impact tests as part of shielding research conducted for the JSC Center Director Discretionary Fund (CDDF) project. The structure tested is a metal foam sandwich structure; a metal foam core between two metal facesheets. Aluminum and Titanium metals were tested for foam sandwich and honeycomb sandwich structures. Aluminum honeycomb core material is currently used in Orbiter Vehicle (OV) radiator panels and in other places in space structures. It has many desirable characteristics and performs well by many measures, especially when normalized by density. Aluminum honeycomb does not perform well in Hypervelocity Impact (HVI) Testing. This is a concern, as honeycomb panels are often exposed to space environments, and take on the role of Micrometeoroid / Orbital Debris (MMOD) shielding. Therefore, information on possible replacement core materials which perform adequately in all necessary functions of the material would be useful. In this report, HVI data is gathered for these two core materials in certain configurations and compared to gain understanding of the metal foam HVI performance.

  6. C60-Fullerene Hyper-Velocity High-Density Plasma Jets for MIF and Disruption Mitigation

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Galkin, S. A.; Kim, J. S.

    2009-06-01

    We present an innovative idea to use hyper-velocity (>30 km/s) high-density (>1017 cm-3) plasma jets of D-T/H and C60-fullerene for magneto-inertial fusion (MIF), high energy density laboratory plasma (HEDLP), and disruption mitigation in magnetic fusion plasma devices. The mass (~1-2 g) of sublimated C60 and hydrogen (or D-T fuel) produced in a pulsed power source is ionized and accelerated as a plasma slug in a coaxial plasma accelerator. For MIF/HEDLP we propose to create a magnetized plasma target by injecting two high-Mach number high-density jets with fuel (D-T) and liner (C60/C) structure along the axis of a pulsed magnetic mirror. The magnetized target fusion (MTF) plasma created by head-on collision and stagnation of jets is compressed radially by a metallic liner (Z-pinch) and axially by the C60/C liner. For disruption mitigation, the C60 plasma jets were shown to be able to provide the required impurity mass (J Fusion Energy 27:6, 2008).

  7. Hypervelocity Impact Test Results for a Metallic Thermal Protection System

    NASA Technical Reports Server (NTRS)

    Karr, Katherine L.; Poteet, Carl C.; Blosser, Max L.

    2003-01-01

    Hypervelocity impact tests have been performed on specimens representing metallic thermal protection systems (TPS) developed at NASA Langley Research Center for use on next-generation reusable launch vehicles (RLV). The majority of the specimens tested consists of a foil gauge exterior honeycomb panel, composed of either Inconel 617 or Ti-6Al-4V, backed with 2.0 in. of fibrous insulation and a final Ti-6Al-4V foil layer. Other tested specimens include titanium multi-wall sandwich coupons as well as TPS using a second honeycomb sandwich in place of the foil backing. Hypervelocity impact tests were performed at the NASA Marshall Space Flight Center Orbital Debris Simulation Facility. An improved test fixture was designed and fabricated to hold specimens firmly in place during impact. Projectile diameter, honeycomb sandwich material, honeycomb sandwich facesheet thickness, and honeycomb core cell size were examined to determine the influence of TPS configuration on the level of protection provided to the substructure (crew, cabin, fuel tank, etc.) against micrometeoroid or orbit debris impacts. Pictures and descriptions of the damage to each specimen are included.

  8. Hypervelocity impact testing of non-metallic materials

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1990-01-01

    A comparative analysis of impact damage in composite and ceramic specimens and in geometrically similar aluminum specimens is performed to determine the advantages and disadvantages of employing certain composite and ceramic materials in the design of structural wall systems for long-duration spacecraft. A similar analysis of the damage in single panel lexan and multi-plane glass windows shows that glass window systems are rather resilent under hypervelocity impact loadings. It is concluded that thin Kevlar 49, IM6/3501-6 graphite/epoxy, and alumina panels offer no advantage over equivalent aluminum 6061-T6 panels in reducing the penetration threat of hypervelocity projectiles.

  9. Improving Metallic Thermal Protection System Hypervelocity Impact Resistance Through Design of Experiments Approach

    NASA Technical Reports Server (NTRS)

    Poteet, Carl C.; Blosser, Max L.

    2001-01-01

    A design of experiments approach has been implemented using computational hypervelocity impact simulations to determine the most effective place to add mass to an existing metallic Thermal Protection System (TPS) to improve hypervelocity impact protection. Simulations were performed using axisymmetric models in CTH, a shock-physics code developed by Sandia National Laboratories, and validated by comparison with existing test data. The axisymmetric models were then used in a statistical sensitivity analysis to determine the influence of five design parameters on degree of hypervelocity particle dispersion. Several damage metrics were identified and evaluated. Damage metrics related to the extent of substructure damage were seen to produce misleading results, however damage metrics related to the degree of dispersion of the hypervelocity particle produced results that corresponded to physical intuition. Based on analysis of variance results it was concluded that the most effective way to increase hypervelocity impact resistance is to increase the thickness of the outer foil layer. Increasing the spacing between the outer surface and the substructure is also very effective at increasing dispersion.

  10. Study of Hypervelocity Projectile Impact on Thick Metal Plates

    SciTech Connect

    Roy, Shawoon K.; Trabia, Mohamed; O’Toole, Brendan; Hixson, Robert S.; Becker, Steven; Pena, Michael T.; Jennings, Richard; Somasoundaram, Deepak; Matthes, Melissa; Daykin, Edward P.; Machorro, Eric

    2016-01-01

    Hypervelocity impacts generate extreme pressure and shock waves in impacted targets that undergo severe localized deformation within a few microseconds. These impact experiments pose unique challenges in terms of obtaining accurate measurements. Similarly, simulating these experiments is not straightforward. This paper proposed an approach to experimentally measure the velocity of the back surface of an A36 steel plate impacted by a projectile. All experiments used a combination of a two-stage light-gas gun and the photonic Doppler velocimetry (PDV) technique. The experimental data were used to benchmark and verify computational studies. Two different finite-element methods were used to simulate the experiments: Lagrangian-based smooth particle hydrodynamics (SPH) and Eulerian-based hydrocode. Both codes used the Johnson-Cook material model and the Mie-Grüneisen equation of state. Experiments and simulations were compared based on the physical damage area and the back surface velocity. Finally, the results of this study showed that the proposed simulation approaches could be used to reduce the need for expensive experiments.

  11. Study of hypervelocity projectile impact on thick metal plates

    DOE PAGESBeta

    Roy, Shawoon K.; Trabia, Mohamed; O’Toole, Brendan; Hixson, Robert S.; Becker, Steven; Pena, Michael T.; Jennings, Richard; Somasoundaram, Deepak; Matthes, Melissa; Daykin, Edward P.; et al

    2016-01-01

    Hypervelocity impacts generate extreme pressure and shock waves in impacted targets that undergo severe localized deformation within a few microseconds. These impact experiments pose unique challenges in terms of obtaining accurate measurements. Similarly, simulating these experiments is not straightforward. This paper proposed an approach to experimentally measure the velocity of the back surface of an A36 steel plate impacted by a projectile. All experiments used a combination of a two-stage light-gas gun and the photonic Doppler velocimetry (PDV) technique. The experimental data were used to benchmark and verify computational studies. Two different finite-element methods were used to simulate the experiments:more » Lagrangian-based smooth particle hydrodynamics (SPH) and Eulerian-based hydrocode. Both codes used the Johnson-Cook material model and the Mie-Grüneisen equation of state. Experiments and simulations were compared based on the physical damage area and the back surface velocity. Finally, the results of this study showed that the proposed simulation approaches could be used to reduce the need for expensive experiments.« less

  12. Study of hypervelocity projectile impact on thick metal plates

    SciTech Connect

    Roy, Shawoon K.; Trabia, Mohamed; O’Toole, Brendan; Hixson, Robert S.; Becker, Steven; Pena, Michael T.; Jennings, Richard; Somasoundaram, Deepak; Matthes, Melissa; Daykin, Edward P.; Machorro, Eric

    2016-01-01

    Hypervelocity impacts generate extreme pressure and shock waves in impacted targets that undergo severe localized deformation within a few microseconds. These impact experiments pose unique challenges in terms of obtaining accurate measurements. Similarly, simulating these experiments is not straightforward. This paper proposed an approach to experimentally measure the velocity of the back surface of an A36 steel plate impacted by a projectile. All experiments used a combination of a two-stage light-gas gun and the photonic Doppler velocimetry (PDV) technique. The experimental data were used to benchmark and verify computational studies. Two different finite-element methods were used to simulate the experiments: Lagrangian-based smooth particle hydrodynamics (SPH) and Eulerian-based hydrocode. Both codes used the Johnson-Cook material model and the Mie-Grüneisen equation of state. Experiments and simulations were compared based on the physical damage area and the back surface velocity. Finally, the results of this study showed that the proposed simulation approaches could be used to reduce the need for expensive experiments.

  13. 3D laser scanning microscopy of hypervelocity impact features in metal and aerogel targets

    NASA Astrophysics Data System (ADS)

    Hillier, J. K.; Postberg, F.; Price, M. C.; Trieloff, M.; Li, Y. W.; Srama, R.

    2012-09-01

    We present the results of a study into the mapping of hypervelocity impact features using a Keyence VK-X200 3D laser scanning microscope. The impact features observed are impact craters in a variety of different metal targets (Al, Au and Cu) and impact tracks in aerogel targets, similar to those used in the Stardust mission. Differences in crater morphology between different target materials and impact velocities, as well as differences in track depth and diameter in aerogel, for particles of known constant dimensions, are discussed.

  14. SEGUE-2 LIMITS ON METAL-RICH OLD-POPULATION HYPERVELOCITY STARS IN THE GALACTIC HALO

    SciTech Connect

    Kollmeier, Juna A.; Gould, Andrew; Johnson, Jennifer A.; Rockosi, Constance; Beers, Timothy C.; Lee, Young Sun; Knapp, Gillian; Morrison, Heather; Harding, Paul; Weaver, Benjamin A.

    2010-11-01

    We present new limits on the ejection of metal-rich old-population hypervelocity stars (HVSs) from the Galactic center (GC) as probed by the SEGUE-2 survey. Our limits are a factor of 3-10 more stringent than previously reported, depending on stellar type. Compared to the known population of B-star ejectees, there can be no more than 30 times more metal-rich old-population F/G stars ejected from the GC. Because B stars comprise a tiny fraction of a normal stellar population, this places significant limits on the combination of the GC mass function and the ejection mechanism for HVSs. In the presence of a normal GC mass function, our results require an ejection mechanism that is about 5.5 times more efficient at ejecting B stars compared to low-mass F/G stars.

  15. Modeling of the merging, liner formation, implosion of hypervelocity plasma jets for the PLX- α project

    NASA Astrophysics Data System (ADS)

    Cassibry, Jason; Hsu, Scott; Schillo, Kevin; Samulyak, Roman; Stoltz, Peter; Beckwith, Kris

    2015-11-01

    A suite of numerical tools will support the conical and 4 π plasma-liner-formation experiments for the PLX- α project. A new Lagrangian particles (LP) method will provide detailed studies of the merging of plasma jets and plasma-liner formation/convergence. A 3d smooth particle hydrodynamic (SPH) code will simulate conical (up to 9 jets) and 4 π spherical (up to 60 jets) liner formation and implosion. Both LP and SPH will use the same tabular EOS generated by Propaceos, thermal conductivity, optically thin radiation and physical viscosity models. With LP and SPH,the major objectives are to study Mach-number degradation during jet merging, provide RMS amplitude and wave number of the liner nonuniformity at the leading edge, and develop scaling laws for ram pressure and liner uniformity as a function of jet parameters. USIM, a 3D multi-fluid plasma code, will be used to perform 1D and 2D simulations of plasma-jet-driven magneto-inertial fusion (PJMIF) to identify initial conditions in which the ``liner gain'' exceeds unity. A brief overview of the modeling program will be provided. Results from SPH modeling to support the PLX- α experimental design will also be presented, including preliminary ram-pressure scaling and non-uniformity characterization.

  16. The techniques of metallic foil electrically exploding driving hypervelocity flyer to more than 10 km/s for shock wave physics experiments

    NASA Astrophysics Data System (ADS)

    Wang, Guiji; He, Jia; Zhao, Jianheng; Tan, Fuli; Sun, Chengwei; Mo, Jianjun; Xong, Xin; Wu, Gang

    2011-09-01

    Electrical explosion of metallic foil or wire is widely used to the fields of material science (preparation of nao-meter materials), dynamics of materials, and high energy density physics. In this paper, the techniques of gaining hypervelocity flyer driven by electrical explosion of metallic foil were researched, which are used to study dynamics of materials and hypervelocity impact modeling of space debris. Based on low inductance technologies of pulsed storage energy capacitor, detonator switch and parallel plate transmission lines with solid films insulation, two sets of experimental apparatuses with storage energy of 14.4 kJ and 40 kJ were developed for launching hypervelocity flyer. By means of the diagnostic technologies of velocity interferometer system for any reflectors and fibre-optic pins, the hypervelocity polyester (Mylar) flyers were gained. For the apparatus of 14.4 kJ, flyer of diameter ϕ6 ˜ ϕ10 mm and thickness of 0.1 ˜ 0.2 mm was accelerated to the hypervelocity of 10 ˜ 14 km/s. And for the apparatus of 40 kJ, flyer of diameter ϕ20 ˜ 30 mm and thickness of 0.2 mm was launched to the velocity of 5 ˜ 8 km/s. The flatness of the flyer is not more than 34 ns for the flyer with diameter of 20 mm, and less than 22 ns for the flyer with diameter of 10 mm. Based on the Lagrange hydrodynamic code, one dimensional simulation was done by introducing database of equation of states, discharging circuit equation and Joule heat equation, and modifying energy equation. The simulation results are well agreed with the experimental results in accelerating processing. The simulation results can provide good advices in designing new experiments and developing new experimental devices. Finally, some experiments of materials dynamics and hypervelocity impact of space debris were done by using the apparatus above. The results show that the apparatus of metallic foil electrically exploding driving hypervelocity flyer is a good and versatile tool for shock dynamics.

  17. The techniques of metallic foil electrically exploding driving hypervelocity flyer to more than 10 km/s for shock wave physics experiments.

    PubMed

    Wang, Guiji; He, Jia; Zhao, Jianheng; Tan, Fuli; Sun, Chengwei; Mo, Jianjun; Xong, Xin; Wu, Gang

    2011-09-01

    Electrical explosion of metallic foil or wire is widely used to the fields of material science (preparation of nao-meter materials), dynamics of materials, and high energy density physics. In this paper, the techniques of gaining hypervelocity flyer driven by electrical explosion of metallic foil were researched, which are used to study dynamics of materials and hypervelocity impact modeling of space debris. Based on low inductance technologies of pulsed storage energy capacitor, detonator switch and parallel plate transmission lines with solid films insulation, two sets of experimental apparatuses with storage energy of 14.4 kJ and 40 kJ were developed for launching hypervelocity flyer. By means of the diagnostic technologies of velocity interferometer system for any reflectors and fibre-optic pins, the hypervelocity polyester (Mylar) flyers were gained. For the apparatus of 14.4 kJ, flyer of diameter φ6 ~ φ10 mm and thickness of 0.1 ~ 0.2 mm was accelerated to the hypervelocity of 10 ~ 14 km/s. And for the apparatus of 40 kJ, flyer of diameter φ20 ~ 30 mm and thickness of 0.2 mm was launched to the velocity of 5 ~ 8 km/s. The flatness of the flyer is not more than 34 ns for the flyer with diameter of 20 mm, and less than 22 ns for the flyer with diameter of 10 mm. Based on the Lagrange hydrodynamic code, one dimensional simulation was done by introducing database of equation of states, discharging circuit equation and Joule heat equation, and modifying energy equation. The simulation results are well agreed with the experimental results in accelerating processing. The simulation results can provide good advices in designing new experiments and developing new experimental devices. Finally, some experiments of materials dynamics and hypervelocity impact of space debris were done by using the apparatus above. The results show that the apparatus of metallic foil electrically exploding driving hypervelocity flyer is a good and versatile tool for shock dynamics

  18. Ram-pressure scaling and non-uniformity characterization of a spherically imploding liner formed by hypervelocity plasma jets

    NASA Astrophysics Data System (ADS)

    Cassibry, Jason; Dougherty, Jesse; Thompson, Seth; Hsu, Scott; Witherspoon, F. D.; University of AL in Huntsville Team; Los Alamos National Laboratory Team; HyperV Technologies Corp. Team

    2014-10-01

    Three-dimensional modeling of plasma liner formation and implosion is performed using the Smoothed Particle Hydrodynamics Code (SPHC) with radiation, thermal transport, and tabular equations of state (EOS), accounting for ionization, in support of a proposed 60-gun plasma liner formation experiment for plasma-jet driven magneto-inertial fusion (PJMIF). Previous SPHC modeling showed that ideal gas law scaling of peak stagnation pressure increased linearly with density and number of jets, quadratically with jet radius and velocity, and inversely with the initial jet length, while results with tabular EOS, thermal transport, and radiation have greater sensitivity to the initial jet distribution. A series of simulations are conducted to study the effects of initial jet conditions on peak ram pressure and liner non-uniformity during plasma liner implosion. The growth rate of large-amplitude density perturbations introduced by the discrete jets are computed and compared with predictions by the Bell-Plesset equation.

  19. Arc jet tests of metallic TPS materials.

    NASA Technical Reports Server (NTRS)

    Centolanzi, F. J.; Zimmerman, N. B.; Probst, H. B.; Lowell, C. E.

    1971-01-01

    Seven thoria dispersed nickel base alloys and one cobalt base alloy, candidates for the Metallic Thermal Protection System for the Space Shuttle Vehicle, were tested simultaneously in an arc jet at a nominal test temperature of 1366 deg K (2000 deg F) and pressure of 0.01 atmospheres. The degradation of the materials after 50 one half-hour cycles in the arc jet simulating Space Shuttle entry conditions was determined utilizing techniques including X-ray diffraction, metallography, and electron beam microprobe.

  20. Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Brown, Warren R.

    2015-08-01

    Hypervelocity stars (HVSs) travel with such extreme velocities that dynamical ejection via gravitational interaction with a massive black hole (MBH) is their most likely origin. Observers have discovered dozens of unbound main-sequence stars since the first in 2005, and the velocities, stellar nature, spatial distribution, and overall numbers of unbound B stars in the Milky Way halo all fit an MBH origin. Theorists have proposed various mechanisms for ejecting unbound stars, and these mechanisms can be tested with larger and more complete samples. HVSs' properties are linked to the nature and environment of the Milky Way's MBH, and, with future proper motion measurements, their trajectories may provide unique probes of the dark matter halo that surrounds the Milky Way.

  1. Magneto-hydrodynamic simulation of hypervelocity neutral plasma jets and their interactions with materials generating extreme conditions

    NASA Astrophysics Data System (ADS)

    Subramaniam, Vivek; Raja, Laxminarayan; Sitaraman, Hariswaran

    2014-10-01

    The development of a Magneto-hydrodynamics (MHD) numerical tool to study high density thermal plasma in a co-axial plasma gun is presented. The MHD governing equations are numerically solved using a matrix free implicit scheme in an unstructured grid finite volume framework. The MHD model is used to characterize the high energy jet which emanates from the accelerator. The solver is then used to predict the conditions created at the surface of a flat plate placed at a fixed distance from the exit of the gun. The model parameters are adjusted so that the energy density of the jet impacting the plate is of the same order of magnitude as that of the Edge Localized Mode (ELM) disruptions in thermonuclear fusion reactors. The idea is to use the pressure and temperature on the plate surface to obtain an estimate of the stress created on the plate due to jet impact. The model is used to quantify damage caused by ELM disruptions on the confining material surface.

  2. Jet-driven redistribution of metal in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Morsony, Brian J.; Heinz, Sebastian; Reynolds, Christopher S.

    2016-04-01

    The ICM in galaxy clusters is metal enriched, typically to about 30% of solar metallicity, out to large radii. However, metals should form mostly in galaxies and remained bound to their progenitor systems. To enrich the ICM, effective mixing of gas needs to occur across large scales. We carry out numerical simulations of mixing driven by AGN jets in dynamical galaxy clusters. These jets lift gas out of the center of the cluster, redistributing metals and adding energy to the ICM. We compare our results to X-ray observations of metallicity in clusters.

  3. Jet-driven redistribution of metal in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Morsony, Brian; Heinz, Sebastian; Reynolds, Christopher; Ruszkowski, Mateusz; Brueggen, Marcus

    2015-08-01

    The ICM in galaxy clusters is metal enriched, typically to about 30% of solar metallicity, out to large radii. However, metals should form mostly in galaxies and remained bound to their progenitor systems. To enrich the ICM, effective mixing of gas needs to occur across large scales. We carry out numerical simulations of mixing driven by AGN jets in dynamical galaxy clusters. These jets lift gas out of the center of the cluster, redistributing metals and adding energy to the ICM. We compare our results to X-ray observations of metallicity in clusters.

  4. Effects of barrel joints on hypervelocity projectiles

    SciTech Connect

    Shahinpoor, M.; Asay, J.R.; Dixon, W.R.; Hawke, R.S.

    1987-01-01

    Development of new hypervelocity launchers is necessary for equation of state (EOS) studies at high impact velocities. The requirements for barrel joint alignment and concentricity at high velocities place severe constraints on fabrication and assembly procedures; small steps or longitudinal direction changes at joints may cause major damage to precision projectiles. Research has been initiated to identify the technical limits of fabrication and assembly tolerances for hypervelocity gun barrels. Numerical and experimental studies have evaluated projectile performance at velocities of 6 to 15 km/s and have identified failure modes for Lexan projectiles with thin metal facings.

  5. Impinging jet separators for liquid metal magnetohydrodynamic power cycles

    NASA Technical Reports Server (NTRS)

    Bogdanoff, D. W.

    1973-01-01

    In many liquid metal MHD power, cycles, it is necessary to separate the phases of a high-speed liquid-gas flow. The usual method is to impinge the jet at a glancing angle against a solid surface. These surface separators achieve good separation of the two phases at a cost of a large velocity loss due to friction at the separator surface. This report deals with attempts to greatly reduce the friction loss by impinging two jets against each other. In the crude impinging jet separators tested to date, friction losses were greatly reduced, but the separation of the two phases was found to be much poorer than that achievable with surface separators. Analyses are presented which show many lines of attack (mainly changes in separator geometry) which should yield much better separation for impinging jet separators).

  6. Progress in hypervelocity impact and protection

    NASA Astrophysics Data System (ADS)

    Thoma, K.; Schaefer, F.; Hiermaier, S.; Schneider, E.

    pressure and impact load. Using tools as described before, results on pressure vessels and their failure behaviour under impact are summarized. - The influence of projectile shape (non spherical impactor shapes) on shielding performance: In the majority of the existing work on hypervelocity impact, a spherical shape of the impacting mass was assumed. Using experiments and numerical simulations, we demonstrate the importance of considering impactor shape. Existing engineering formulas for shield design are extended to include shape effects and are described in the paper. - The behaviour of metallic foams under hypervelocity impact : Novel metallic foams seem to possess properties, which allow to design shields with superior protection efficiency and superior structural properties. The usage of such metal foams as a shield component is shown through an experimental analysis.

  7. Thermo Physics Facilities Branch Brochure ARC Jet Complex Fact Sheets, Hypervelocity Free-Flight Aerodynamic Facility Fact Sheets, Ames Vertical Gun Range Fact Sheets

    NASA Technical Reports Server (NTRS)

    Fretter, E. F. (Editor); Kuhns, Jay (Editor); Nuez, Jay (Editor)

    2003-01-01

    The Ames Arc Jet Complex has a rich heritage of over 40 years in Thermal Protection System (TPS) development for every NASA Space Transportation and Planetary program, including Apollo, Space Shuttle, Viking, Pioneer-Venus, Galileo, Mars Pathfinder,Stardust, NASP,X-33,X-34,SHARP-B1 and B2,X-37 and Mars Exploration Rovers. With this early TPS history came a long heritage in the development of the arc jet facilities. These are used to simulate the aerodynamic heating that occurs on the nose cap, wing leading edges and on other areas of the spacecraft requiring thermal protection. TPS samples have been run in the arc jets from a few minutes to over an hour,from one exposure to multiple exposures of the same sample, in order t o understand the TPS materials response to a hot gas flow environment (representative of real hyperthermal environments experienced in flight). The Ames Arc l e t Complex is a key enabler for customers involved in the three major areas of TPS development: selection, validation, and qualification. The arc jet data are critical for validating TPS thermal models, heat shield designs and repairs, and ultimately for flight qualification.

  8. Cosmology with hypervelocity stars

    SciTech Connect

    Loeb, Abraham

    2011-04-01

    In the standard cosmological model, the merger remnant of the Milky Way and Andromeda (Milkomeda) will be the only galaxy remaining within our event horizon once the Universe has aged by another factor of ten, ∼ 10{sup 11} years after the Big Bang. After that time, the only extragalactic sources of light in the observable cosmic volume will be hypervelocity stars being ejected continuously from Milkomeda. Spectroscopic detection of the velocity-distance relation or the evolution in the Doppler shifts of these stars will allow a precise measurement of the vacuum mass density as well as the local matter distribution. Already in the near future, the next generation of large telescopes will allow photometric detection of individual stars out to the edge of the Local Group, and may target the ∼ 10{sup 5±1} hypervelocity stars that originated in it as cosmological tracers.

  9. Hypervelocity impact physics

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Bean, Alan J.; Darzi, Kent

    1991-01-01

    All large spacecraft are susceptible to impacts by meteoroids and orbiting space debris. These impacts occur at extremely high speed and can damage flight-critical systems, which can in turn lead to a catastrophic failure of the spacecraft. Therefore, the design of a spacecraft for a long-duration mission must take into account the possibility of such impacts and their effects on the spacecraft structure and on all of its exposed subsystems components. The work performed under the contract consisted of applied research on the effects of meteoroid/space debris impacts on candidate materials, design configurations, and support mechanisms of long term space vehicles. Hypervelocity impact mechanics was used to analyze the damage that occurs when a space vehicle is impacted by a micrometeoroid or a space debris particle. An impact analysis of over 500 test specimens was performed to generate by a hypervelocity impact damage database.

  10. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    NASA Astrophysics Data System (ADS)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2015-07-01

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O2 = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  11. Hypervelocity microparticle characterization

    SciTech Connect

    Idzorek, G.C.

    1996-11-01

    To protect spacecraft from orbital debris requires a basic understanding of the processes involved in hypervelocity impacts and characterization of detectors to measure the space environment. Both require a source of well characterized hypervelocity particles. Electrostatic acceleration of charged microspheres provides such a source. Techniques refined at the Los Alamos National Laboratory provided information on hypervelocity impacts of particles of known mass and velocity ranging from 20-1000 nm diameter and 1-100 km/s. A Van De Graaff generator operating at 6 million volts was used to accelerate individual carbonyl iron microspheres produced by a specially designed particle source. Standard electrostatic lenses and steering were used to control the particles flight path. Charge sensitive pickoff tubes measured the particle charge and velocity in- flight without disturbing the particle. This information coupled with the measured Van De Graaff terminal voltage allowed calculation of the particle energy, mass, momenta and (using an assumed density) the size. Particles with the desired parameters were then electrostatically directed to a target chamber. Targets used in our experiments included cratering and foil puncture targets, microphone momentum enhancement detectors, triboluminescent detectors, and ``splash`` charge detectors. In addition the system has been used to rapidly characterize size distributions of conductive plastic particles and potentially provide a method of easily sorting microscopic particles by size.

  12. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    SciTech Connect

    Norberg, Seth A. Johnsen, Eric; Kushner, Mark J.

    2015-07-07

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O{sub 2} = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  13. Shuttle Hypervelocity Impact Database

    NASA Technical Reports Server (NTRS)

    Hyde, James L.; Christiansen, Eric L.; Lear, Dana M.

    2011-01-01

    With three missions outstanding, the Shuttle Hypervelocity Impact Database has nearly 3000 entries. The data is divided into tables for crew module windows, payload bay door radiators and thermal protection system regions, with window impacts compromising just over half the records. In general, the database provides dimensions of hypervelocity impact damage, a component level location (i.e., window number or radiator panel number) and the orbiter mission when the impact occurred. Additional detail on the type of particle that produced the damage site is provided when sampling data and definitive analysis results are available. Details and insights on the contents of the database including examples of descriptive statistics will be provided. Post flight impact damage inspection and sampling techniques that were employed during the different observation campaigns will also be discussed. Potential enhancements to the database structure and availability of the data for other researchers will be addressed in the Future Work section. A related database of returned surfaces from the International Space Station will also be introduced.

  14. Shuttle Hypervelocity Impact Database

    NASA Technical Reports Server (NTRS)

    Hyde, James I.; Christiansen, Eric I.; Lear, Dana M.

    2011-01-01

    With three flights remaining on the manifest, the shuttle impact hypervelocity database has over 2800 entries. The data is currently divided into tables for crew module windows, payload bay door radiators and thermal protection system regions, with window impacts compromising just over half the records. In general, the database provides dimensions of hypervelocity impact damage, a component level location (i.e., window number or radiator panel number) and the orbiter mission when the impact occurred. Additional detail on the type of particle that produced the damage site is provided when sampling data and definitive analysis results are available. The paper will provide details and insights on the contents of the database including examples of descriptive statistics using the impact data. A discussion of post flight impact damage inspection and sampling techniques that were employed during the different observation campaigns will be presented. Future work to be discussed will be possible enhancements to the database structure and availability of the data for other researchers. A related database of ISS returned surfaces that are under development will also be introduced.

  15. Oxidation of Reinforced Carbon-Carbon Subjected to Hypervelocity Impact

    NASA Technical Reports Server (NTRS)

    Curry, Donald M.; Pham, Vuong T.; Norman, Ignacio; Chao, Dennis C.

    2000-01-01

    This paper presents results from arc jet tests conducted at the NASA Johnson Space Center on reinforced carbon-carbon (RCC) samples subjected to hypervelocity impact. The RCC test specimens are representative of RCC components used on the Space Shuttle Orbiter. The arc jet testing established the oxidation characteristics of RCC when hypervelocity projectiles, simulating meteoroid/orbital debris, impact the RCC material. In addition to developing correlations for use in trajectory simulations, we discuss analytical modeling of the increased material oxidation in the impacted area using measured hole growth data. Entry flight simulations are useful in assessing the increased Space Shuttle RCC component degradation as a result of impact damage and the hot gas flow through an enlarging hole into the wing leading-edge cavity.

  16. Conical shaped charge pressed powder, metal liner jet characterization and penetration in aluminum

    SciTech Connect

    Vigil, M.G.

    1997-05-01

    This work was conducted as part of a Near-wellbore Mechanics program at Sandia National Laboratories. An understanding of the interaction of the perforator jet from an explosive shaped charge with the fluid filled porous sandstone media is of basic importance to the completion of oil wells. Tests were conducted using the five-head Flash X-ray Test Site to measure the jet tip velocities and jet geometry for the OMNI and CAPSULE Conical Shaped Charge (CSC) oil well perforator jets fired into air. These tests were conducted to generate jet velocity and geometry information to be used in validating the CTH hydrocode modeling/simulation development of pressed powder, metal liner jets in air. Ten tests were conducted to determine the CSC jet penetration into 6061-T6 aluminum targets. Five tests were conducted with the OMNI CSC at 0.25, 6.0, and 19 inch standoffs from the target. Five tests were conducted with the CAPSULE CSC at 0.60, 5.0, 10.0, and 19 inch standoffs from the target. These tests were conducted to generate jet penetration into homogeneous target information for use in validating the CTH code modeling/simulation of pressed powder, metal liner jets penetrating aluminum targets. The Flash X-ray radiographs, jet velocities, jet diameters, and jet lengths data for jets fired into air are presented in this report. The jet penetration into aluminum and penetration hole profile data are also presented for the OMNI and CAPSULE perforators. Least Squares fits are presented for the measured jet velocity and jet penetration data.

  17. Intact capture of hypervelocity particles

    NASA Technical Reports Server (NTRS)

    Tsou, P.; Brownlee, D. E.; Albee, A. L.

    1986-01-01

    Knowledge of the phase, structure, and crystallography of cosmic particles, as well as their elemental and isotopic compositions, would be very valuable information toward understanding the nature of our solar system. This information can be obtained from the intact capture of large mineral grains of cosmic particles from hypervelocity impacts. Hypervelocity experiments of intact capture in underdense media have indicated realistic potential in this endeaver. The recovery of the thermal blankets and louvers from the Solar Max spacecraft have independently verified this potential in the unintended capture of cosmic materials from hypervelocity impacts. Passive underdense media will permit relatively simple and inexpensive missions to capture cosmic particles intact, either by going to a planetary body or by waiting for the particles to come to the Shuttle or the Space Station. Experiments to explore the potential of using various underdense media for an intact comet sample capture up to 6.7 km/s were performed at NASA Ames Research Center Vertical Gun Range. Explorative hypervelocity experiments up to 7.9 km/s were also made at the Ernst Mach Institute. These experiments have proven that capturing intact particles at hypervelocity impacts is definitely possible. Further research is being conducted to achieve higher capture ratios at even higher hypervelocities for even smaller projectiles.

  18. Intact capture of hypervelocity particles

    NASA Astrophysics Data System (ADS)

    Tsou, P.; Brownlee, D. E.; Albee, A. L.

    Knowledge of the phase, structure, and crystallography of cosmic particles, as well as their elemental and isotopic compositions, would be very valuable information toward understanding the nature of our solar system. This information can be obtained from the intact capture of large mineral grains of cosmic particles from hypervelocity impacts. Hypervelocity experiments of intact capture in underdense media have indicated realistic potential in this endeaver. The recovery of the thermal blankets and louvers from the Solar Max spacecraft have independently verified this potential in the unintended capture of cosmic materials from hypervelocity impacts. Passive underdense media will permit relatively simple and inexpensive missions to capture cosmic particles intact, either by going to a planetary body or by waiting for the particles to come to the Shuttle or the Space Station. Experiments to explore the potential of using various underdense media for an intact comet sample capture up to 6.7 km/s were performed at NASA Ames Research Center Vertical Gun Range. Explorative hypervelocity experiments up to 7.9 km/s were also made at the Ernst Mach Institute. These experiments have proven that capturing intact particles at hypervelocity impacts is definitely possible. Further research is being conducted to achieve higher capture ratios at even higher hypervelocities for even smaller projectiles.

  19. Hypervelocity impacts into graphite

    NASA Astrophysics Data System (ADS)

    Latunde-Dada, S.; Cheesman, C.; Day, D.; Harrison, W.; Price, S.

    2011-03-01

    Studies have been conducted into the characterisation of the behaviour of commercial graphite (brittle) when subjected to hypervelocity impacts by a range of projectiles. The experiments were conducted with a two-stage gas gun capable of launching projectiles of differing density and strength to speeds of about 6kms-1 at right angles into target plates. The damage caused is quantified by measurements of the crater depth and diameters. From the experimental data collected, scaling laws were derived which correlate the crater dimensions to the velocity and the density of the projectile. It was found that for moderate projectile densities the crater dimensions obey the '2/3 power law' which applies to ductile materials.

  20. Ink-jet printing of silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, R. W.

    1986-01-01

    The status of the ink-jet printing program at Purdue University is described. The drop-on-demand printing system was modified to use metallo-organic decomposition (MOD) inks. Also, an IBM AT computer was integrated into the ink-jet printer system to provide operational functions and contact pattern configuration. The integration of the ink-jet printing system, problems encountered, and solutions derived were described in detail. The status of ink-jet printing using a MOD ink was discussed. The ink contained silver neodecanate and bismuth 2-ethylhexanoate dissolved in toluene; the MOD ink decomposition products being 99 wt% AG, and 1 wt% Bi.

  1. Removal of Machine Oil from Metal Surface by Mesoplasma Jet under Open Atmosphere

    NASA Astrophysics Data System (ADS)

    Saito, Haruki; Shiki, Hajime; Tsujii, Kenichi; Oke, Shinichiro; Suda, Yoshiyuki; Takikawa, Hirofumi; Okawa, Takashi; Yamanaka, Shigenobu

    2009-08-01

    An attempt was made to employ the plasma-energized jet (PEN-jet) generated by pulsed arc discharge, one of the atmospheric-pressure mesoplasmas, for removal of machine oil from the surface of electrically-grounded aluminum (Al) alloy substrate under open atmosphere. Three types of nozzle configurations were examined; a metal nozzle, ceramic nozzle, and electrically-floated metal nozzle. Electric input power to the pulsed arc plasma discharge was 700 W constant. First, free-burning of the PEN-jet was observed as a function of air gas flow. When the PEN-jets were irradiated to the clean substrate, the PEN-jet with the metal nozzle caused substrate damage by the arc spot due to transferring arc discharge. Then the PEN-jet with the ceramic nozzle was irradiated to the oily substrate. The adhesion strength of sealant and water contact angle of the treated surface were then measured. As a result, these values of the oily substrate treated by the PEN-jet were almost the same as those of clean substrate. The treated surface was analyzed by Fourier transform infrared spectroscopy, Raman spectroscopy, and reflectance spectroscopy. Their spectral profiles clearly indicated oil removal from the surface by PEN-jet.

  2. Analysis of heat transfer for a normally impinging liquid-metal slot jet

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1973-01-01

    A two-dimensional liquid-metal slot jet that is impinging normally against a uniformly heated flat plate is analyzed. The distributions of wall temperature and heat-transfer coefficient are obtained as functions of position along the plate. The liquid-metal assumptions are made that the jet is inviscid and that molecular condition is dominating heat diffusion. The solution is obtained by mapping the jet flow region into a potential plane where it occupies a strip of uniform width. The energy equation is transformed into potential coordinates, and an exact solution obtained in the strip region. Conformal mapping is then used to transform the solution into the physical plane.

  3. Hypervelocity impact shield

    NASA Technical Reports Server (NTRS)

    Cour-Palais, Burton G. (Inventor); Crews, Jeanne Lee (Inventor)

    1991-01-01

    A hypervelocity impact shield and method for protecting a wall structure, such as a spacecraft wall, from impact with particles of debris having densities of about 2.7 g/cu cm and impact velocities up to 16 km/s are disclosed. The shield comprises a stack of ultra thin sheets of impactor disrupting material supported and arranged by support means in spaced relationship to one another and mounted to cover the wall in a position for intercepting the particles. The sheets are of a number and spacing such that the impacting particle and the resulting particulates of the impacting particle and sheet material are successively impact-shocked to a thermal state of total melt and/or vaporization to a degree as precludes perforation of the wall. The ratio of individual sheet thickness to the theoretical diameter of particles of debris which may be of spherical form is in the range of 0.03 to 0.05. The spacing between adjacent sheets is such that the debris cloud plume of liquid and vapor resulting from an impacting particle penetrating a sheet does not puncture the next adjacent sheet prior to the arrival thereat of fragment particulates of sheet material and the debris particle produced by a previous impact.

  4. Capacitors Would Help Protect Against Hypervelocity Impacts

    NASA Technical Reports Server (NTRS)

    Edwards, David; Hubbs, Whitney; Hovater, Mary

    2007-01-01

    A proposal investigates alternatives to the present bumper method of protecting spacecraft against impacts of meteoroids and orbital debris. The proposed method is based on a British high-voltage-capacitance technique for protecting armored vehicles against shaped-charge warheads. A shield, according to the proposal, would include a bare metal outer layer separated by a gap from an inner metal layer covered with an electrically insulating material. The metal layers would constitute electrodes of a capacitor. A bias potential would be applied between the metal layers. A particle impinging at hypervelocity on the outer metal layer would break apart into a debris cloud that would penetrate the electrical insulation on the inner metal layer. The cloud would form a path along which electric current could flow between the metal layers, thereby causing the capacitor to discharge. With proper design, the discharge current would be large enough to vaporize the particles in the debris cloud to prevent penetration of the spacecraft. The shield design can be mass optimized to be competitive with existing bumper designs. Parametric studies were proposed to determine optimum correction between bias voltage, impacting particle velocity, gap space, and insulating material required to prevent spacecraft penetration.

  5. Metal and polymer melt jet formation by the high-power laser ablation

    NASA Astrophysics Data System (ADS)

    Yoh, Jack J.; Gojani, Ardian B.

    2010-02-01

    The laser-induced metal and polymer melt jets are studied experimentally. Two classes of physical phenomena of interest are: first, the process of explosive phase change of laser induced surface ablation and second, the hydrodynamic jetting of liquid melts ejected from a beamed spot. We focus on the dynamic link between these two distinct physical phenomena in a framework of forming and patterning of metallic and polymer jets using a high-power Nd:YAG laser. The microexplosion of ablative spot on a target first forms a pocket of hot liquid melt and then it is followed by a sudden volume change of gas-liquid mixture leading to a pressure-induced spray jet ejection into surrounding medium.

  6. Ink jet printing of silver metallization for photovoltaics

    NASA Technical Reports Server (NTRS)

    Vest, R. W.

    1985-01-01

    Progress was made in the continuing development of the ink jet printing system for thick film circuits. The unit being used is a prototype ink jet printer. One of the first tasks completed was the complete documentation of this ink jet printing system as it existed. It was determined that this was an essential step in deciding what modifications were needed to the system and how these modifications would be implemented. Design modification studies were started for electronic, mechanical, and programming aspects of the ystem. The areas needeing improvement were discussed and applicable changes decided upon. Some improvments were completed. Although the general areas needing improving were identified and some changes decided upon, the exact details of how other changes can be implemented are yet been decided.

  7. Three-phase hypervelocity projectile launcher

    DOEpatents

    Fugelso, L. Erik; Langner, Gerald C.; Burns, Kerry L.; Albright, James N.

    1994-01-01

    A hypervelocity projectile launcher for use in perforating borehole casings provides improved penetration into the surrounding rock structure. The launcher includes a first cylinder of explosive material that defines an axial air-filled cavity, a second cylinder of explosive material defining an axial frustum-shaped cavity abutting and axially aligned with the first cylinder. A pliant washer is located between and axially aligned with the first and second cylinders. The frustum shaped cavity is lined with a metal liner effective to form a projectile when the first and second cylinders are detonated. The washer forms a unique intermediate projectile in advance of the liner projectile and enables the liner projectile to further penetrate into and fracture the adjacent rock structure.

  8. X-ray grating interferometry with a liquid-metal-jet source

    SciTech Connect

    Thüring, T.; Rutishauser, S.; Stampanoni, M.; Zhou, T.; Lundström, U.; Burvall, A.; Hertz, H. M.; David, C.

    2013-08-26

    A liquid-metal-jet X-ray tube is used in an X-ray phase-contrast microscope based on a Talbot type grating interferometer. With a focal spot size in the range of a few microns and a photon flux of ∼10{sup 12} photons/s×sr, the brightness of such a source is approximately one order of magnitude higher than for a conventional microfocus source. For comparison, a standard microfocus source was used with the same grating interferometer, showing significantly increased visibility for the liquid-metal-jet arrangement. Together with the increased flux, this results in improved signal-to-noise ratio.

  9. Mod silver metallization: Screen printing and ink-jet printing

    NASA Technical Reports Server (NTRS)

    Vest, R. W.; Vest, G. M.

    1985-01-01

    Basic material efforts have proven to be very successful. Adherent and conductive films were achieved. A silver neodecanoate/bismuth 2-ethylhexanoate mixture has given the best results in both single and double layer applications. Another effort is continuing to examine the feasibility of applying metallo-organic deposition films by use of an ink jet printer. Direct line writing would result in a saving of process time and materials. So far, some well defined lines have been printed.

  10. Mod silver metallization: Screen printing and ink-jet printing

    NASA Astrophysics Data System (ADS)

    Vest, R. W.; Vest, G. M.

    1985-06-01

    Basic material efforts have proven to be very successful. Adherent and conductive films were achieved. A silver neodecanoate/bismuth 2-ethylhexanoate mixture has given the best results in both single and double layer applications. Another effort is continuing to examine the feasibility of applying metallo-organic deposition films by use of an ink jet printer. Direct line writing would result in a saving of process time and materials. So far, some well defined lines have been printed.

  11. Removal of metals and ceramics by combined effects of micro liquid jet and laser pulse

    NASA Astrophysics Data System (ADS)

    Ahn, Daehwan; Seo, Changho; Kim, Dongsik

    2012-12-01

    In this work, we analyze a hybrid laser/liquid jet micromachining process for several metals and ceramics based on the optical breakdown of a microdroplet. In the process, materials are removed by the combined effects of a laser pulse and a high-speed pulsed microjet ejected from the microdroplet. The opto-hydrodynamic phenomena occurring during this process and the interaction of the laser/liquid jet with various materials, including copper, aluminum, stainless steel, alumina, and boron nitride, are investigated experimentally. The results show that the laser/liquid jet can remove the materials with substantially increased removal rates and reduced thermal side effects compared with the conventional pulsed laser ablation process. Visualization of the process reveals that the materials are partially ablated and melted by the laser pulse during the early stage of the process and that the molten material is subsequently eliminated by the hydrodynamic impact of the liquid jet.

  12. Jet formation in cerium metal to examine material strength

    SciTech Connect

    Jensen, B. J. Cherne, F. J.; Prime, M. B.; Yeager, J. D.; Ramos, K. J.; Hooks, D. E.; Cooley, J. C.; Dimonte, G.; Fezzaa, K.; Iverson, A. J.; Carlson, C. A.

    2015-11-21

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2–3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.

  13. Jet formation in cerium metal to examine material strength

    NASA Astrophysics Data System (ADS)

    Jensen, B. J.; Cherne, F. J.; Prime, M. B.; Fezzaa, K.; Iverson, A. J.; Carlson, C. A.; Yeager, J. D.; Ramos, K. J.; Hooks, D. E.; Cooley, J. C.; Dimonte, G.

    2015-11-01

    Examining the evolution of material properties at extreme conditions advances our understanding of numerous high-pressure phenomena from natural events like meteorite impacts to general solid mechanics and fluid flow behavior. Recent advances in synchrotron diagnostics coupled with dynamic compression platforms have introduced new possibilities for examining in-situ, spatially resolved material response with nanosecond time resolution. In this work, we examined jet formation from a Richtmyer-Meshkov instability in cerium initially shocked into a transient, high-pressure phase, and then released to a low-pressure, higher-temperature state. Cerium's rich phase diagram allows us to study the yield stress following a shock induced solid-solid phase transition. X-ray imaging was used to obtain images of jet formation and evolution with 2-3 μm spatial resolution. From these images, an analytic method was used to estimate the post-shock yield stress, and these results were compared to continuum calculations that incorporated an experimentally validated equation-of-state (EOS) for cerium coupled with a deviatoric strength model. Reasonable agreement was observed between the calculations and the data illustrating the sensitivity of jet formation on the yield stress values. The data and analysis shown here provide insight into material strength during dynamic loading which is expected to aid in the development of strength aware multi-phase EOS required to predict the response of matter at extreme conditions.

  14. Flash x-ray radiography using imaging plates for the observation of hypervelocity objects

    SciTech Connect

    Mizusako, F.; Ogasawara, K.; Kondo, K.; Saito, F.; Tamura, H.

    2005-02-01

    Flash x-ray radiography was conducted using imaging plates (IP) to observe high-speed thermal spray jets and debris clouds produced from hypervelocity impact. The radiographs of the spray jets or debris cloud shadows on the IPs were analyzed to estimate the distribution of mass per unit area, i.e., Areal mass density, due to the distribution of the intensities of stimulated emissions from the IPs. The wide dynamic range of the IPs led to the detection of an Areal mass density one hundred times as large as the minimum Areal mass density and the very detailed densities. The availability of the IPs for the flash x-ray radiography of a high-speed thermal spray jet and a hypervelocity-impact-produced debris cloud was demonstrated.

  15. Hypervelocity plate acceleration

    SciTech Connect

    Marsh, S.P.; Tan, T.H.

    1991-01-01

    Shock tubes have been used to accelerate 1.5-mm-thick stainless steel plates to high velocity while retaining their integrity. The fast shock tubes are 5.1-cm-diameter, 15.2-cm-long cylinders of PBX-9501 explosive containing a 1.1-cm-diameter cylindrical core of low-density polystyrene foam. The plates have been placed directly in contact with one face of the explosive system. Plane-wave detonation was initiated on the opposite face. A Mach disk was formed in the imploding styrofoam core, which provided the impulse required to accelerate the metal plate to high velocity. Parametric studies were made on this system to find the effect of varying plate metal, plate thickness, foam properties, and addition of a barrel. A maximum plate velocity of 9.0 km/s has been observed. 6 refs., 17 figs.

  16. Possibility of Metal Processing Using Ultrasonic Cavitation Jet

    NASA Astrophysics Data System (ADS)

    Aoyagi, Ryoji; Fujiwara, Ryuichi; Niita, Tokuo

    2001-05-01

    Utilizing a high-intensity ultrasonic cavitation, a processing experiment was conducted with the aim of performing volumetric flow adjustment of a fuel jet nozzle to be used for a small engine, which cannot be carried out by a method such as machining. At the bottom of the nozzle used for the experiment, which is in the shape of a cup, a nozzle hole with a diameter of 0.15 mm is drilled. In this experiment, we make adjustments in the volumetric flow by grinding and removing the machining burr with the aid of the processing power of ultrasonic cavitation. The processing effect is highly dependent on the ultrasonic cavitation intensity. In the experiment, the processing reservoir was filled with pressurized highly deaerated water to increase the processing force by allowing cavitation with high intensity to be generated. The processing principle is to utilize the effect of a cavitation jet flow passing through the nozzle hole. To restrain the intake of the bubbles into the flow circuits during the pressure reduction cycle of the vibrator, the water flow was discharged into a pressure reduction reservoir. By allowing the horn tip with a diameter of 6 mm at a frequency of 28 kHz to approach the sample, followed by high-intensity ultrasonic irradiation, powerful cavitation was generated. As a result of the evaluation of the processing efficiency made based on the volumetric flow increase and microscopic observation of the nozzle, burrs smaller than 10 μm were almost entirely removed within 15 min of initial irradiation, resulting in a volumetric flow increase of more than 0.4%/min. However, in the case of burrs of more than 10 μm, no force that could remove the burrs was found. It was surprising for the burrs to generate deformation rather than to be removed.

  17. Chunk projectile launch using the Sandia Hypervelocity Launcher Facility

    SciTech Connect

    Chhabildas, L.C.; Trucano, T.G.; Reinhart, W.D.; Hall, C.A.

    1994-07-01

    An experimental technique is described to launch an intact ``chunk,`` i.e. a 0.3 cm thick by 0.6 cm diameter cylindrical titanium alloy (Ti-6Al-4V) flyer, to 10.2 km/s. The ability to launch fragments having such an aspect ratio is important for hypervelocity impact phenomenology studies. The experimental techniques used to accomplish this launch were similar but not identical to techniques developed for the Sandia HyperVelocity Launcher (HVL). A confined barrel impact is crucial in preventing the two-dimensional effects from dominating the loading response of the projectile chunk. The length to diameter ratio of the metallic chunk that is launched to 10.2 km/s is 0.5 and is an order of magnitude larger than those accomplished using the conventional hypervelocity launcher. The multi-dimensional, finite-difference (finite-volume), hydrodynamic code CTH was used to evaluate and assess the acceleration characteristics i.e., the in-bore ballistics of the chunky projectile launch. A critical analysis of the CTH calculational results led to the final design and the experimental conditions that were used in this study. However, the predicted velocity of the projectile chunk based on CTH calculations was {approximately} 6% lower than the measured velocity of {approximately}10.2 km/S.

  18. Characterization of Debris from the DebriSat Hypervelocity Test

    NASA Technical Reports Server (NTRS)

    Rivero, M.; Kleespies, J.; Patankar, K.; Fitz-Coy, N.; Liou, J.-C.; Sorge, M.; Huynh, T.; Opiela, J.; Krisko, P.; Cowardin, H.

    2015-01-01

    The DebriSat project is an effort by NASA and the DoD to update the standard break-up model for objects in orbit. The DebriSat object, a 56 kg representative LEO satellite, was subjected to a hypervelocity impact in April 2014. For the hypervelocity test, the representative satellite was suspended within a "soft-catch" arena formed by polyurethane foam panels to minimize the interactions between the debris generated from the hypervelocity impact and the metallic walls of the test chamber. After the impact, the foam panels and debris not caught by the panels were collected and shipped to the University of Florida where the project has now advanced to the debris characterization stage. The characterization effort has been divided into debris collection, measurement, and cataloguing. Debris collection and cataloguing involves the retrieval of debris from the foam panels and cataloguing the debris in a database. Debris collection is a three-step process: removal of loose debris fragments from the surface of the foam panels; X-ray imaging to identify/locate debris fragments embedded within the foam panel; extraction of the embedded debris fragments identified during the X-ray imaging process. As debris fragments are collected, they are catalogued into a database specifically designed for this project. Measurement involves determination of size, mass, shape, material, and other physical properties and well as images of the fragment. Cataloguing involves a assigning a unique identifier for each fragment along with the characterization information.

  19. Hypervelocity cutting machine and method

    DOEpatents

    Powell, J.R.; Reich, M.

    1996-11-12

    A method and machine are provided for cutting a workpiece such as concrete. A gun barrel is provided for repetitively loading projectiles therein and is supplied with a pressurized propellant from a storage tank. A thermal storage tank is disposed between the propellant storage tank and the gun barrel for repetitively receiving and heating propellant charges which are released in the gun barrel for repetitively firing projectiles therefrom toward the workpiece. In a preferred embodiment, hypervelocity of the projectiles is obtained for cutting the concrete workpiece by fracturing thereof. 10 figs.

  20. Hypervelocity cutting machine and method

    DOEpatents

    Powell, James R.; Reich, Morris

    1996-11-12

    A method and machine 14 are provided for cutting a workpiece 12 such as concrete. A gun barrel 16 is provided for repetitively loading projectiles 22 therein and is supplied with a pressurized propellant from a storage tank 28. A thermal storage tank 32,32A is disposed between the propellant storage tank 28 and the gun barrel 16 for repetitively receiving and heating propellant charges which are released in the gun barrel 16 for repetitively firing projectiles 22 therefrom toward the workpiece 12. In a preferred embodiment, hypervelocity of the projectiles 22 is obtained for cutting the concrete workpiece 12 by fracturing thereof.

  1. A 24 keV liquid-metal-jet x-ray source for biomedical applications

    SciTech Connect

    Larsson, D. H.; Takman, P. A. C.; Lundstroem, U.; Burvall, A.; Hertz, H. M.

    2011-12-15

    We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30-70 W electron beam is magnetically focused onto the jet, producing a circular 7-13 {mu}m full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In K{sub {alpha}} line is 3 x 10{sup 9} photons/(s x mm{sup 2}x mrad{sup 2}x 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

  2. Features of deformation of metal body surfaces under impact of a water jet

    NASA Astrophysics Data System (ADS)

    Aganin, A. A.; Khismatullina, N. A.

    2016-01-01

    The paper presents a mathematical model and computational results on dynamics of a perfect elastic-plastic body under the load arising during impact of a high-velocity liquid jet with the hemispherical end. The body is simulated by the isotropic linearly-elastic semi-space, its plastic state is described by the von Mises condition. The dependence of features of the body surface deformation on the body material is studied. The problem is considered in the axisymmetric statement. The axis of symmetry is that of the jet. The loaded domain is a circle with its radius rapidly growing from zero to the jet radius. The pressure in the loaded domain is non-uniform both in time and space. Three metal alloys (aluminium, copper-nickel and steel) are considered as the body material. The loading of the body surface in all the cases corresponds to the impact of a water jet with the radius 100 pm and the velocity 300 m/s. It has been shown that under such impact a nanometer pit arises on the body surface at the center of the domain of the jet action. The profile of the pit and its maximal depth depend on the body material.

  3. Sharp Hypervelocity Aerodynamic Research Probe

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey; Kolodziej, Paul; Rasky, Daniel J. (Technical Monitor)

    1996-01-01

    The objective of this flight demonstration is to deploy a slender-body hypervelocity aerodynamic research probe (SHARP) from an orbiting platform using a tether, deorbit and fly it along its aerothermal performance constraint, and recover it intact in mid-air. To accomplish this objective, two flight demonstrations are proposed. The first flight uses a blunt-body, tethered reentry experiment vehicle (TREV) to prove out tethered deployment technology for accurate entries, a complete SHARP electronics suite, and a new soft mid-air helicopter recovery technique. The second flight takes advantage of this launch and recovery capability to demonstrate revolutionary sharp body concepts for hypervelocity vehicles, enabled by new Ultra-High Temperature Ceramics (UHTCs) recently developed by Ames Research Center. Successful demonstration of sharp body hypersonic vehicle technologies could have radical impact on space flight capabilities, including: enabling global reentry cross range capability from Station, eliminating reentry communications blackout, and allowing new highly efficient launch systems incorporating air breathing propulsion and zeroth staging.

  4. Ablative shielding for hypervelocity projectiles

    NASA Technical Reports Server (NTRS)

    Rucker, Michelle A. (Inventor)

    1993-01-01

    A hypervelocity projectile shield which includes a hollow semi-flexible housing fabricated from a plastic like, or otherwise transparent membrane which is filled with a fluid (gas or liquid) is presented. The housing has a inlet valve, similar to that on a tire or basketball, to introduce an ablating fluid into the housing. The housing is attached by a Velcro mount or double-sided adhesive tape to the outside surface of a structure to be protected. The housings are arrayed in a side-by-side relationship for complete coverage of the surface to be protected. In use, when a hypervelocity projectile penetrates the outer wall of a housing it is broken up and then the projectile is ablated as it travels through the fluid, much like a meteorite 'burns up' as it enters the earth's atmosphere, and the housing is deflated. The deflated housing can be easily spotted for replacement, even from a distance. Replacement is then accomplished by simply pulling a deflated housing off the structure and installing a new housing.

  5. Ink jet assisted metallization for low cost flat plate solar cells

    NASA Technical Reports Server (NTRS)

    Teng, K. F.; Vest, R. W.

    1987-01-01

    Computer-controlled ink-jet-assisted metallization of the front surface of solar cells with metalorganic silver inks offers a maskless alternative method to conventional photolithography and screen printing. This method can provide low cost, fine resolution, reduced process complexity, avoidance of degradation of the p-n junction by firing at lower temperature, and uniform line film on rough surface of solar cells. The metallization process involves belt furnace firing and thermal spiking. With multilayer ink jet printing and firing, solar cells of about 5-6 percent efficiency without antireflection (AR) coating can be produced. With a titanium thin-film underlayer as an adhesion promoter, solar cells of average efficiency 8.08 percent without AR coating can be obtained. This efficiency value is approximately equal to that of thin-film solar cells of the same lot. Problems with regard to lower inorganic content of the inks and contact resistance are noted.

  6. Ink jet printable silver metallization with zinc oxide for front side metallization for micro crystalline silicon solar cells

    NASA Astrophysics Data System (ADS)

    Jurk, Robert; Fritsch, Marco; Eberstein, Markus; Schilm, Jochen; Uhlig, Florian; Waltinger, Andreas; Michaelis, Alexander

    2015-12-01

    Ink jet printable water based inks are prepared by a new silver nanoparticle synthesis and the addition of nanoscaled ZnO particles. For the formation of front side contacts the inks are ink jet printed on the front side of micro crystalline silicon solar cells, and contact the cell directly during the firing step by etching through the wafers’ anti-reflection coating (ARC). In terms of Ag dissolution and precipitation the mechanism of contact formation can be compared to commercial glass containing thick film pastes. This avoids additional processing steps, like laser ablation, which are usually necessary to open the ARC prior to ink jet printing. As a consequence process costs can be reduced. In order to optimize the ARC etching and contact formation during firing, zinc oxide nanoparticles are investigated as an ink additive. By utilization of in situ contact resistivity measurements the mechanism of contacting was explored. Our results show that silver inks containing ZnO particles realize a specific contact resistance below 10 mΩṡcm2. By using a multi-pass ink jet printing and plating process a front side metallization of commercial 6  ×  6 inch2 standard micro crystalline silicone solar cells with emitter resistance of 60 Ω/◽ was achieved and showed an efficiency of 15.7%.

  7. Heat Transfer Between a Plasma Jet and a Metal Surface in a Cut Cavity

    NASA Astrophysics Data System (ADS)

    Veremeichik, A. N.; Sazonov, M. I.; Khvisevich, V. M.; Tsyganov, D. L.

    2015-11-01

    Investigations are presented of the formation of a plasma jet and of the current-density and heat-flux distributions in the process of metal cutting along the cut cavity with direct and reverse polarities of the plasmatron connection. The study of the specific features of heat transfer of the arc with the surface of the cut cavity was carried out on the basis of the developed plasma unit which makes it possible to model the technological process of separating metal cutting. A sectional cut model is proposed which can be used to work out and optimize the methods of determination of cutting parameters.

  8. Hypervelocity High Speed Projectile Imagery and Video

    NASA Technical Reports Server (NTRS)

    Henderson, Donald J.

    2009-01-01

    This DVD contains video showing the results of hypervelocity impact. One is showing a projectile impact on a Kevlar wrapped Aluminum bottle containing 3000 psi gaseous oxygen. One video show animations of a two stage light gas gun.

  9. Hypervelocity impact simulations of Whipple shields

    NASA Technical Reports Server (NTRS)

    Segletes, Steven B.; Zukas, Jonas A.

    1992-01-01

    The problem associated with protecting space vehicles from space debris impact is described. Numerical simulation is espoused as a useful complement to experimentation: as a means to help understand and describe the hypervelocity impact phenomena. The capabilities of a PC-based hydrocode, ZeuS, are described, for application to the problem of hypervelocity impact. Finally, results of ZeuS simulations, as applied to the problem of bumper shield impact, are presented and compared with experimental results.

  10. Hypervelocity Impact (HVI). Volume 1; General Introduction

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. This volume contains an executive summary, overview of the method, brief descriptions of all targets, and highlights of results and conclusions.

  11. Hypervelocity impact technology and applications: 2007.

    SciTech Connect

    Reinhart, William Dodd; Chhabildas, Lalit C.

    2008-07-01

    The Hypervelocity Impact Society is devoted to the advancement of the science and technology of hypervelocity impact and related technical areas required to facilitate and understand hypervelocity impact phenomena. Topics of interest include experimental methods, theoretical techniques, analytical studies, phenomenological studies, dynamic material response as related to material properties (e.g., equation of state), penetration mechanics, and dynamic failure of materials, planetary physics and other related phenomena. The objectives of the Society are to foster the development and exchange of technical information in the discipline of hypervelocity impact phenomena, promote technical excellence, encourage peer review publications, and hold technical symposia on a regular basis. It was sometime in 1985, partly in response to the Strategic Defense Initiative (SDI), that a small group of visionaries decided that a conference or symposium on hypervelocity science would be useful and began the necessary planning. A major objective of the first Symposium was to bring the scientists and researchers up to date by reviewing the essential developments of hypervelocity science and technology between 1955 and 1985. This Symposia--HVIS 2007 is the tenth Symposium since that beginning. The papers presented at all the HVIS are peer reviewed and published as a special volume of the archival journal International Journal of Impact Engineering. HVIS 2007 followed the same high standards and its proceedings will add to this body of work.

  12. Fragmentation of hypervelocity aluminum projectiles on fabrics

    NASA Astrophysics Data System (ADS)

    Rudolph, Martin; Schäfer, Frank; Destefanis, Roberto; Faraud, Moreno; Lambert, Michel

    2012-07-01

    This paper presents work performed for a study investigating the ability of different flexible materials to induce fragmentation of a hypervelocity projectile. Samples were chosen to represent a wide range of industrially available types of flexible materials like ceramic, aramid and carbon fabrics as well as a thin metallic mesh. Impact conditions and areal density were kept constant for all targets. Betacloth and multi-layer insulation (B-MLI) are mounted onto the targets to account for thermal system engineering requirements. All tests were performed using the Space light-gas gun facility (SLGG) of the Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI. Projectiles were aluminum spheres with 5 mm diameter impacting at approximately 6.3 km/s. Fragmentation was evaluated using a witness plate behind the target. An aramid and a ceramic fabric lead the ranking of fabrics with the best projectile fragmentation and debris cloud dispersion performance. A comparison with an equal-density rigid aluminum plate is presented. The work presented can be applied to optimize the micrometeoroid and space debris (MM/SD) shielding structure of inflatable modules.

  13. Advanced Hypervelocity Aerophysics Facility Workshop

    NASA Technical Reports Server (NTRS)

    Witcofski, Robert D. (Compiler); Scallion, William I. (Compiler)

    1989-01-01

    The primary objective of the workshop was to obtain a critical assessment of a concept for a large, advanced hypervelocity ballistic range test facility powered by an electromagnetic launcher, which was proposed by the Langley Research Center. It was concluded that the subject large-scale facility was feasible and would provide the required ground-based capability for performing tests at entry flight conditions (velocity and density) on large, complex, instrumented models. It was also concluded that advances in remote measurement techniques and particularly onboard model instrumentation, light-weight model construction techniques, and model electromagnetic launcher (EML) systems must be made before any commitment for the construction of such a facility can be made.

  14. Intact capture of hypervelocity projectiles.

    PubMed

    Tsou, P

    1990-01-01

    The ability to capture projectiles intact at hypervelocities opens new applications in science and technology that would either not be possible or would be very costly by other means. This capability has been demonstrated in the laboratory for aluminum projectiles of 1.6 mm diameter, captured at 6 km/s, in one unmelted piece, and retaining up to 95% of the original mass. Furthermore, capture was accomplished passively using microcellular underdense polymer foam. Another advantage of capturing projectiles in an underdense medium is the ability of such a medium to preserve a record of the projectile's original velocity components of speed and direction. A survey of these experimental results is described in terms of a dozen parameters which characterize the amount of capture and the effect on the projectile due to different capture media. PMID:11538362

  15. Small-animal tomography with a liquid-metal-jet x-ray source

    NASA Astrophysics Data System (ADS)

    Larsson, D. H.; Lundström, U.; Westermark, U.; Takman, P. A. C.; Burvall, A.; Arsenian Henriksson, M.; Hertz, H. M.

    2012-03-01

    X-ray tomography of small animals is an important tool for medical research. For high-resolution x-ray imaging of few-cm-thick samples such as, e.g., mice, high-brightness x-ray sources with energies in the few-10-keV range are required. In this paper we perform the first small-animal imaging and tomography experiments using liquid-metal-jet-anode x-ray sources. This type of source shows promise to increase the brightness of microfocus x-ray systems, but present sources are typically optimized for an energy of 9 keV. Here we describe the details of a high-brightness 24-keV electron-impact laboratory microfocus x-ray source based on continuous operation of a heated liquid-In/Ga-jet anode. The source normally operates with 40 W of electron-beam power focused onto the metal jet, producing a 7×7 μm2 FWHM x-ray spot. The peak spectral brightness is 4 × 109 photons / ( s × mm2 × mrad2 × 0.1%BW) at the 24.2 keV In Kα line. We use the new In/Ga source and an existing Ga/In/Sn source for high-resolution imaging and tomography of mice.

  16. On the Nature of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Ginsburg, Idan

    2013-12-01

    Hypervelocity stars are stars ejected from the center of the Milky Way, never to return. Since first discovered in 2005, hypervelocity stars have greatly increased our understanding of the kinematics and dynamics at the Galactic Center. In this dissertation we show via gravitational N-body simulations that an encounter between a binary star and the massive black hole at the Galactic Center, Sgr A*, can produce a hypervelocity star for one component of the binary, while the companion star remains in a tight orbit around the black hole. Such an encounter can also result in the coalescence of both stars in a highly-eccentric orbit around the black hole. These mechanisms may explain the surprising appearance of massive stars within 1OEOE of Sgr A*. We further find that the disruption of a triple star system by the massive black hole can produce hypervelocity binaries, which may ultimately coalesce and evolve into unbound blue stragglers. The black hole may also capture a binary star system, or possibly all three stars when a triple system is disrupted. Such captures may lead to collisions between two or all three of the stars and the coalescence may result in the formation of rejuvenated stars. Oursimulations also predict that planets around stars can be ejected from the Galactic Center via the same mechanism that produces hypervelocity stars. However, typical velocities for such runaway planets are higher than their stellar counterparts, with velocities approaching 5% the speed of light in extreme cases. Planets may also collide with their host star and result in an enriched stellar atmosphere. Furthermore, hypervelocity stars may host planets that should have a detectable transit. The discovery of such a transit would have consequences for understanding planetary formation and evolution at the Galactic Center. It is difficult to positively identify hypervelocity stars since at the observed effective temperatures both main-sequence and blue horizontal branch stars

  17. Explosively driven hypervelocity launcher: Second-stage augmentation techniques

    NASA Technical Reports Server (NTRS)

    Baum, D. W.

    1973-01-01

    The results are described of a continuing study aimed at developing a two-stage explosively driven hypervelocity launcher capable of achieving projectile velocities between 15 and 20 km/sec. The testing and evaluation of a new cylindrical impact technique for collapsing the barrel of two-stage launcher are reported. Previous two-stage launchers have been limited in ultimate performance by incomplete barrel collapse behind the projectile. The cylindrical impact technique explosively collapses a steel tube concentric with and surrounding the barrel of the launcher. The impact of the tube on the barrel produces extremely high stresses which cause the barrel to collapse. The collapse rate can be adjusted by appropriate variation of the explosive charge and tubing parameters. Launcher experiments demonstrated that the technique did achieve complete barrel collapse and form a second-stage piston. However, jetting occurred in the barrel collapse process and was responsible for severe projectile damage.

  18. PVDF gauge characterization of hypervelocity-impact-generated debris clouds

    SciTech Connect

    Boslough, M.B.; Chhabildas, L.C.; Reinhart, W.D.; Hall, C.A.; Miller, J.M.; Hickman, R.; Mullin, S.A.; Littlefield, D.L.

    1993-08-01

    We have used PVDF gauges to determine time-resolved stresses resulting from interaction between hypervelocity-impact-generated debris clouds and various target gauge blocks. Debris clouds were generated from three different impact configurations: (1) steel spheres impacting steel bumper sheets at 4.5 to 6.0 km/s, (2) aluminum inhibited shaped-charge jets impacting aluminum bumper sheets at 11.4 km/s, and (3) titanium disks impacting titanium bumper sheets at 7.6 to 10.1 km/s. Additional data were collected from the various experiments using flash X-ray radiography, pulsed laser photography, impact flash measurements, time-resolved strain gauge measurements, and velocity interferometry (VISAR). Data from these various techniques are in general agreement with one another and with hydrocode predictions, and provide a quantitative and comprehensive picture of impact-generated debris clouds.

  19. AXAF hypervelocity impact test results

    NASA Technical Reports Server (NTRS)

    Frost, Cynthia L.; Rodriguez, Pedro I.

    1997-01-01

    Composite and honeycomb panels are commonly used for spacecraft structural components. The impact test results and analysis of six different composite and honeycomb combinations for use on the advanced X-ray astrophysics facility (AXAF) are reported. The AXAF consists of an X-ray telescope and the associated detecting devices attached to an octagonal spacecraft with an internal propulsion system. The spacecraft's structural panels and optical bench are made of two different graphite fiber reinforced polyimides or composite panels bonded to either side of an aluminum honeycomb. The instrument is required to have at least a 0.92 probability of no failure of any of the critical elements due to meteoroids and debris. In relation to the no-failure probability determination in its low earth orbit environment, hypervelocity impact testing was performed to determine the ballistic limit range and the extent of damage due to impact. The test results for a power and signal cable bundle located behind a panel are presented. Tests planned for a multilayer insulation (MLI) blanket and four types of cable bundles are discussed.

  20. Hypervelocity Capability of the HYPULSE Shock-Expansion Tunnel for Scramjet Testing

    NASA Technical Reports Server (NTRS)

    Foelsche, Robert O.; Rogers, R. Clayton; Tsai, Ching-Yi; Bakos, Robert J.; Shih, Ann T.

    2001-01-01

    New hypervelocity capabilities for scramjet testing have recently been demonstrated in the HYPULSE Shock-Expansion Tunnel (SET). With NASA's continuing interests in scramjet testing at hypervelocity conditions (Mach 12 and above), a SET nozzle was designed and added to the HYPULSE facility. Results of tests conducted to establish SET operational conditions and facility nozzle calibration are presented and discussed for a Mach 15 (M15) flight enthalpy. The measurements and detailed computational fluid dynamics calculations (CFD) show the nozzle delivers a test gas with sufficiently wide core size to be suitable for free-jet testing of scramjet engine models of similar scale as, those tested in conventional low Mach number blow-down test facilities.

  1. Hypervelocity impact testing of spacecraft optical sensors

    SciTech Connect

    1995-07-01

    Hypervelocity tests of spacecraft optical sensors were conducted to determine if the optical signature from an impact inside the optical sensor sunshade resembled signals that have been observed on-orbit. Impact tests were conducted in darkness and with the ejected debris illuminated. The tests were conducted at the Johnson Space Center Hypervelocity Impact Test Facility. The projectile masses and velocities that may be obtained at the facility are most representative of the hypervelocity particles thought to be responsible for a group of anomalous optical sensors responses that have been observed on-orbit. The projectiles are a few micrograms, slightly more massive than the microgram particles thought to be responsible for the signal source. The test velocities were typically 7.3 km/s, which are somewhat slower than typical space particles.

  2. Analysis of oblique hypervelocity impact phenomena

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Taylor, Roy A.

    1988-01-01

    This paper describes the results of an experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to a meteoroid or space debris environement.

  3. An investigation of oblique hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1987-01-01

    This report describes the results of an investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multi-sheet aluminum structures. A model to be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations relating crater and perforation damage of a multi-sheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multi-sheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the hazardous meteoroid and space debris environment.

  4. Laser jetting of femto-liter metal droplets for high resolution 3D printed structures.

    PubMed

    Zenou, M; Sa'ar, A; Kotler, Z

    2015-01-01

    Laser induced forward transfer (LIFT) is employed in a special, high accuracy jetting regime, by adequately matching the sub-nanosecond pulse duration to the metal donor layer thickness. Under such conditions, an effective solid nozzle is formed, providing stability and directionality to the femto-liter droplets which are printed from a large gap in excess of 400 μm. We illustrate the wide applicability of this method by printing several 3D metal objects. First, very high aspect ratio (A/R > 20), micron scale, copper pillars in various configuration, upright and arbitrarily bent, then a micron scale 3D object composed of gold and copper. Such a digital printing method could serve the generation of complex, multi-material, micron-scale, 3D materials and novel structures. PMID:26602432

  5. Metal shell technology based upon hollow jet instability. [for inertial confinement fusion

    NASA Technical Reports Server (NTRS)

    Kendall, J. M.; Lee, M. C.; Wang, T. G.

    1982-01-01

    Spherical shells of submillimeter size are sought as ICF targets. Such shells must be dimensionally precise, smooth, of high strength, and composed of a high atomic number material. A technology for the production of shells based upon the hydrodynamic instability of an annular jet of molten metal is described. Shells in the 0.7-2.0 mm size range have been produced using tin as a test material. Specimens exhibit good sphericity, fair concentricity, and excellent finish over most of the surface. Work involving a gold-lead-antimony alloy is in progress. Droplets of this are amorphous and possess superior surface finish. The flow of tin models that of the alloy well; experiments on both metals show that the technique holds considerable promise.

  6. Laser jetting of femto-liter metal droplets for high resolution 3D printed structures

    PubMed Central

    Zenou, M.; Sa’ar, A.; Kotler, Z.

    2015-01-01

    Laser induced forward transfer (LIFT) is employed in a special, high accuracy jetting regime, by adequately matching the sub-nanosecond pulse duration to the metal donor layer thickness. Under such conditions, an effective solid nozzle is formed, providing stability and directionality to the femto-liter droplets which are printed from a large gap in excess of 400 μm. We illustrate the wide applicability of this method by printing several 3D metal objects. First, very high aspect ratio (A/R > 20), micron scale, copper pillars in various configuration, upright and arbitrarily bent, then a micron scale 3D object composed of gold and copper. Such a digital printing method could serve the generation of complex, multi-material, micron-scale, 3D materials and novel structures. PMID:26602432

  7. Laser jetting of femto-liter metal droplets for high resolution 3D printed structures

    NASA Astrophysics Data System (ADS)

    Zenou, M.; Sa'Ar, A.; Kotler, Z.

    2015-11-01

    Laser induced forward transfer (LIFT) is employed in a special, high accuracy jetting regime, by adequately matching the sub-nanosecond pulse duration to the metal donor layer thickness. Under such conditions, an effective solid nozzle is formed, providing stability and directionality to the femto-liter droplets which are printed from a large gap in excess of 400 μm. We illustrate the wide applicability of this method by printing several 3D metal objects. First, very high aspect ratio (A/R > 20), micron scale, copper pillars in various configuration, upright and arbitrarily bent, then a micron scale 3D object composed of gold and copper. Such a digital printing method could serve the generation of complex, multi-material, micron-scale, 3D materials and novel structures.

  8. Element fracture technique for hypervelocity impact simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-tian; Li, Xiao-gang; Liu, Tao; Jia, Guang-hui

    2015-05-01

    Hypervelocity impact dynamics is the theoretical support of spacecraft shielding against space debris. The numerical simulation has become an important approach for obtaining the ballistic limits of the spacecraft shields. Currently, the most widely used algorithm for hypervelocity impact is the smoothed particle hydrodynamics (SPH). Although the finite element method (FEM) is widely used in fracture mechanics and low-velocity impacts, the standard FEM can hardly simulate the debris cloud generated by hypervelocity impact. This paper presents a successful application of the node-separation technique for hypervelocity impact debris cloud simulation. The node-separation technique assigns individual/coincident nodes for the adjacent elements, and it applies constraints to the coincident node sets in the modeling step. In the explicit iteration, the cracks are generated by releasing the constrained node sets that meet the fracture criterion. Additionally, the distorted elements are identified from two aspects - self-piercing and phase change - and are deleted so that the constitutive computation can continue. FEM with the node-separation technique is used for thin-wall hypervelocity impact simulations. The internal structures of the debris cloud in the simulation output are compared with that in the test X-ray graphs under different material fracture criteria. It shows that the pressure criterion is more appropriate for hypervelocity impact. The internal structures of the debris cloud are also simulated and compared under different thickness-to-diameter ratios (t/D). The simulation outputs show the same spall pattern with the tests. Finally, the triple-plate impact case is simulated with node-separation FEM.

  9. Computational design of hypervelocity launchers

    SciTech Connect

    Trucano, T.; Chhabildas, L.

    1993-12-31

    The Sandia Hypervelocity Launcher (HVL) uses impact techniques on a two-stage light-gas gun to launch flier plates to velocities in excess of 10 km/s. An important problem in designing successful third stage techniques for impact launching fliers to such velocities is detailed understanding of the interior ballistic performance of the third stage. This is crucial for preventing melt and fracture of the flier plates during the extraordinary accelerations that they undergo (accelerations on the order of 10{sup 9} g are typical on the HVL). We seek to optimize HVL launch conditions in order to achieve two major goals: first, to maximize the potential launch velocity for a given flier, and second, to allow different flier configurations. One tool that we can apply in studying HVL performance is the use of multi-dimensional wave propagation codes. We have used such codes, particularly the Sandia Eulerian code CTH, to study a variety of interior ballistics issues related to gun performance and launcher development for almost ten years. Recently this work has culminated in a major contribution to HVL design, namely the capability to launch ``chunk`` fliers. `Me initial phases of design development were solely devoted to CTH computations that studied potential designs, identified problems, and posed possible solutions for launching chunk fliers on the HVL. Our computations sufficiently narrowed the design space to the point that systematic experimental progress was possible. Our first experiment resulted in the successful launch of an intact 0.33 gram titanium alloy chunk flier to a velocity of 10.2 km/s. The thickness to diameter ratio of this flier was approximately 0.5.

  10. Crater and cavity depth in hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Kadono, T.; Fujiwara, A.

    2003-04-01

    Hypervelocity impact experiments with low-density mediums (e.g., foams) have been so far carried out to develop the instruments for intact capture of interplanetary dust particles. The results show that the impact leads a "cavity", a cylindrical or carrot (spindle) shaped vestige. Its shape depends on the condition of projectiles; when impact velocity is so low that projectiles are intact, the depth increases with impact velocity, while it decreases or is constant with impact velocity when the impact velocity is so high that projectiles are broken (e.g., Kadono, Planet. Space Sci. 47, 305--318, 1999). On the other hand, as described by Summers (NASA TN D-94, 1959), crater shape with high density targets (comparable to projectile density) also changes with impact velocity. At low velocities, the strength of projectile's materials is greater than the dynamic impact pressure and the projectile penetrates the target intact. The crater produced is deep and narrow. With increase in impact velocity, a point is reached at which the impact pressure is sufficient to cause the projectile to fragment into a few large pieces at impact. Then as the impact velocity is increased further, the projectile shatters into numerous small pieces and the penetration actually decreases. Finally a velocity is reached at which the typical fluid impact occurs, the crater formed is nearly hemispherical in shape. It appears that the situation in cavity formation with low density targets is quite similar to that in cratering with high density targets at low impact velocity. This similarity allows us to discuss cavity formation and cratering in a unified view. As described above, the previous experiments clearly suggest that the condition of projectiles plays important roles in both cratering and cavity formation. Hence here, by introducing a parameter that characterizes the condition of projectiles at the instance of impact, cratering processes such as projectile penetration and shock wave

  11. Demonstration of Hazardous Hypervelocity Test Capability

    NASA Technical Reports Server (NTRS)

    Rodriquez, Karen M.

    1991-01-01

    NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) participated in a joint test program with NASA JSC Hypervelocity Impact Research Laboratory (HIRL) to determine if JSC was capable of performing hypervelocity impact tests on hazardous targets. Seven pressurized vessels were evaluated under hypervelocity impact conditions. The vessels were tested with various combinations of liquids and gasses at various pressures. Results from the evaluation showed that vessels containing 100-percent pressurized gas sustained more severe damage and had a higher potential for damaging nearby equipment, than vessels containing 75-percent liquid, 25-percent inert pressurized gas. Two water-filled test vessels, one of which was placed behind an aluminum shield, failed by bulging and splitting open at the impact point; pressure was relieved without the vessel fragmenting or sustaining internal damage. An additional water-filled test vessel, placed a greater distance behind an aluminum shield, sustained damage that resembled a shotgun blast, but did not bulge or split open; again, pressure was relieved without the vessel fragmenting. Two test vessels containing volatile liquids (nitro methane and hydrazine) also failed by bulging and splitting open; neither liquid detonated under hypervelocity test conditions. A test vessel containing nitrogen gas failed by relieving pressure through a circular entry hole; multiple small penetrations opposite the point of entry provided high velocity target debris to surrounding objects. A high-pressure oxygen test vessel fragmented upon impact; the ensuing fire and high velocity fragments caused secondary damage to surrounding objects. The results from the evaluation of the pressurized vessels indicated that JSC is capable of performing hypervelocity impact tests on hazardous targets.

  12. Simulating plasma production from hypervelocity impacts

    NASA Astrophysics Data System (ADS)

    Fletcher, Alex; Close, Sigrid; Mathias, Donovan

    2015-09-01

    Hypervelocity particles, such as meteoroids and space debris, routinely impact spacecraft and are energetic enough to vaporize and ionize themselves and as well as a portion of the target material. The resulting plasma rapidly expands into the surrounding vacuum. While plasma measurements from hypervelocity impacts have been made using ground-based technologies such as light gas guns and Van de Graaff dust accelerators, some of the basic plasma properties vary significantly between experiments. There have been both ground-based and in-situ measurements of radio frequency (RF) emission from hypervelocity impacts, but the physical mechanism responsible and the possible connection to the impact-produced plasma are not well understood. Under certain conditions, the impact-produced plasma can have deleterious effects on spacecraft electronics by providing a new current path, triggering an electrostatic discharge, causing electromagnetic interference, or generating an electromagnetic pulse. Multi-physics simulations of plasma production from hypervelocity impacts are presented. These simulations incorporate elasticity and plasticity of the solid target, phase change and plasma formation, and non-ideal plasma physics due to the high density and low temperature of the plasma. A smoothed particle hydrodynamics method is used to perform a continuum dynamics simulation with these additional physics. By examining a series of hypervelocity impacts, basic properties of the impact produced plasma plume (density, temperature, expansion speed, charge state) are determined for impactor speeds between 10 and 72 km/s. For a large range of higher impact speeds (30-72 km/s), we find the temperature is unvarying at 2.5 eV. We also find that the plasma plume is weakly ionized for impact speeds less than 14 km/s and fully ionized for impact speeds greater than 20 km/s, independent of impactor mass. This is the same velocity threshold for the detection of RF emission in recent Van de Graaff

  13. EROSIVE WEAR OF DUCTILE METALS BY A PARTICLE-LADEN HIGH-VELOCITY LIQUID-JET

    SciTech Connect

    Li, Simon Ka-Keung; Humphrey, Joseph A.C.; Levy, Alan

    1980-12-01

    A liquid-solid particle jet impingement flow apparatus is described and experimental measurements are reported for the accelerated erosion of copper, aluminum and mild steel sheet metal by coal suspensions in kerosene and alumina and silicon carbide suspensions in water. Slurry velocities of up to 130 ft/sec (40 m/sec) and impingement angles ranging from 15 degrees to 90 degrees were investigated. The maximum particle concentration used was 40% by weight. For high velocity the results of this study show two erosion maxima arising at impingement angles of 90 degrees and 40 degrees respectively~ whereas in corresponding gas-solid particle investigations maximum erosion occurs at approximately 20 degrees. In the study both particle concentration and composition were varied. A polynomial regression technique was used to calculate empirical and semi-theoretical correlation constants.

  14. Observation of Hypervelocity Dust in Dense Supersonic Plasma Flows: Physics and Applications

    NASA Astrophysics Data System (ADS)

    Ticoş, C. M.; Wang, Z.; Wurden, G. A.; Shukla, P. K.

    2008-10-01

    Synthetic diamond and graphite dust powders with a wide range of sizes, from a few to several tens of microns in diameter were accelerated to velocities up to 4 km/s in vacuum by plasma jet produced in a coaxial gun. Some of the key features of the plasma flow are high density, of the order of 1022 m-3, low ion and electron temperatures, of only a few eV, and good collimation over a distance of ≈2 m due to confinement by the self-generated magnetic field. The main features of this plasma-drag acceleration technique are presented and discussed. From basic science point of view hypervelocity dust is useful for studying the physics of dust interaction with energetic plasma flows at microscopic level. In physical applications, it has been proposed to use hypervelocity dust for diagnostic or control of magnetically confined fusion plasmas. In engineering, hypervelocity dusty plasmas are extensively employed in industrial processes involved in the processing of surfaces.

  15. Observation of Hypervelocity Dust in Dense Supersonic Plasma Flows: Physics and Applications

    SciTech Connect

    Ticos, C. M.; Wang, Z.; Wurden, G. A.; Shukla, P. K.

    2008-10-15

    Synthetic diamond and graphite dust powders with a wide range of sizes, from a few to several tens of microns in diameter were accelerated to velocities up to 4 km/s in vacuum by plasma jet produced in a coaxial gun. Some of the key features of the plasma flow are high density, of the order of 10{sup 22} m{sup -3}, low ion and electron temperatures, of only a few eV, and good collimation over a distance of {approx_equal}2 m due to confinement by the self-generated magnetic field. The main features of this plasma-drag acceleration technique are presented and discussed. From basic science point of view hypervelocity dust is useful for studying the physics of dust interaction with energetic plasma flows at microscopic level. In physical applications, it has been proposed to use hypervelocity dust for diagnostic or control of magnetically confined fusion plasmas. In engineering, hypervelocity dusty plasmas are extensively employed in industrial processes involved in the processing of surfaces.

  16. Experimental Study of Spacecraft Material Ejected upon Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Francesconi, A.; Giacomuzzo, C.; Barilaro, L.; Segato, E.; Sansone, F.

    2013-08-01

    Twenty-eight hypervelocity impact experiments were carried out at CISAS impact facility, with the aim of assessing the amount of ejecta from three different targets representative of spacecraft materials, i.e. simple aluminum-alloy plates, silicon solar cells and simple aluminum-alloy plates covered by MLI blankets. Projectiles having different size (1, 1.5 and 2.3 mm diameter) were launched at speed ranging from 4 to 5.5 km/s and impact angle from 0° to 80° (the impact angle dependence was evaluated for simple aluminium targets only). Experiments pointed out that the number of ejecta produced after HVI is significantly high (order of thousands). Moreover, it was shown that brittle materials produce more fragments than ductile ones, but the environment pollution and the damage potential of particles coming from metals are much more critical, since large and heavy fragments are prevalent in this case.

  17. A research program in magnetogasdynamics utilizing hypervelocity coaxial plasma generators

    NASA Technical Reports Server (NTRS)

    Spight, C.

    1976-01-01

    A broadly-gauged research program in magnetogasdynamics utilizing hypervelocity coaxial plasma generators is presented. A complete hypervelocity coaxial plasma generator facility was assembled and tested. Significant progress was made in the direction of understanding the important processes in the interaction of hypervelocity MGD flow with transverse applied fields. It is now proposed to utilize the accumulated experimental capability and theoretical analysis in application to the analysis and design parameterization of pulsed magnetogasdynamic direct energy convertor configurations.

  18. Analysis of hypervelocity impact test data

    SciTech Connect

    Canavan, G.H.

    1998-01-01

    Experiments conducted by the Department of Defense provide an adequate basis for the determination of the fragment distribution and number from hypervelocity collisions. Models trained on only a portion of the data are shown to bias samples too far from the population to be useful for averaging over debris distributions or estimating fragment production rates. The average fragment production exponent is more appropriate for those purposes.

  19. Experimental observations of the breakup of multiple metal jets in a volatile liquid

    SciTech Connect

    Marciniak, M.J.

    1995-07-01

    A postulated severe loss of coolant accident in a nuclear reactor can lead to significant core damage due to residual heat generation. Subsequently, melted core materials (i.e.; corium) could migrate downward and impinge upon the lower head of the reactor pressure vessel (RPV). During this relocation, the complexity of the reactor structure could segregate the molten corium into various flow paths. A perforated flow plate could readily provide the mechanism to segregate the molten corium. The resulting small (a few cm) diameter melt streams, driven by gravity, could then penetrate the remaining coolant in the RPV and cause any of the following events: impingement of the high temperature melt streams on the lower head could breach the RPV; re-agglomeration of the corium melt on the lower head could influence the coolability of the debris bed; {open_quotes}pre-mixing{close_quotes} of the melt streams with the coolant could lead to a vapor explosion; or, sufficient quenching of the melt streams by the coolant could produce a stabilized debris bed. An overview of the thermo-science issues related to core-melt accidents is presented by Theofanous. Thus, insight into the melt stream breakup mechanisms (i.e.; interfacial conditions, fragmentation, and geometric spacing) during the melt-coolant interactions is necessary to evaluate the plausibility, and characteristics, of these events. Molten Fuel Stream Breakup Simulation (MFSBS) experiments have been performed at Argonne National Laboratory in which simulant materials were used to determine a `boiling` jet breakup length correlation and to visualize the melt fragmentation mechanisms during the penetration of a single molten metal jet into a volatile liquid. The goal was to characterize the hydrodynamics of the corium-water interactions in a postulated core melt accident. The present experiment closely follows the procedures of the MFSBS.

  20. NOTE: Survivability of Bacteria in Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Burchell, Mark J.; Mann, Jo; Bunch, Alan W.; Brandão, Pedro F. B.

    2001-12-01

    Bacteria belonging to the genus Rhodococcus have been tested for their survivability in hypervelocity impacts at 5.1±0.1 km s -1. This is similar to the martian escape velocity for example but is slower than the mean velocities typical of impacts from space on planets like Mars (typically 14 km s -1) and Earth (typically 20-25 km s -1). The bacteria fired were loaded on a projectile using a two-stage light-gas gun. The targets were plates of nutrient media. Analysis techniques including pyrolysis mass spectrometry and selective growth in acetonitrile confirmed that the bacterium grown on a target plate after a shot was the original strain. The indication is that, if fired on a projectile, bacteria can survive a hypervelocity impact and subsequently grow. This holds implications for the study of possible natural migration of life around the Solar System on minor bodies which end up impacting target planets, thus transferring life if the bacteria can survive the resulting hypervelocity impact.

  1. Numerical Simulation of the Interaction Between Supersonic Oxygen Jets and Molten Slag-Metal Bath in Steelmaking BOF Process

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Li, Mingming; Kuang, Shibo; Zou, Zongshu

    2015-02-01

    The impinging of multiple jets onto the molten bath in the BOF steelmaking process plays a crucial role in reactor performance but is not clearly understood. This paper presents a numerical study of the interaction between the multiple jets and slag-metal bath in a BOF by means of the three-phase volume of fluid model. The validity of the model is first examined by comparing the numerical results with experimental measurement of time-averaged cavity dimensions through a scaled-down water model. The calculated results are in reasonably good agreement with the experimental data. The mathematical model is then used to investigate the primary transport phenomena of the jets-bath interaction inside a 150-ton commercial BOF under steelmaking conditions. The numerical results show that the cavity profile and interface of slag/metal/gas remain unstable as a result of the propagation of surface waves, which, likely as a major factor, governs the generation of metal droplets and their initial spatiotemporal distribution. The total momentum transferred from the jets into the bath is consumed about a half to drive the movement of slag, rather than fully converted as the stirring power for the metal bath. Finally, the effects of operational conditions and fluid properties are quantified. It is shown that compared to viscosity and surface tension of the melts, operating pressure and lance height have a much more significant impact on the slag-metal interface behavior and cavity shape as well as the fluid dynamics in the molten bath.

  2. Simulating plasma production from hypervelocity impacts

    SciTech Connect

    Fletcher, Alex Close, Sigrid; Mathias, Donovan

    2015-09-15

    Hypervelocity particles, such as meteoroids and space debris, routinely impact spacecraft and are energetic enough to vaporize and ionize themselves and as well as a portion of the target material. The resulting plasma rapidly expands into the surrounding vacuum. While plasma measurements from hypervelocity impacts have been made using ground-based technologies such as light gas guns and Van de Graaff dust accelerators, some of the basic plasma properties vary significantly between experiments. There have been both ground-based and in-situ measurements of radio frequency (RF) emission from hypervelocity impacts, but the physical mechanism responsible and the possible connection to the impact-produced plasma are not well understood. Under certain conditions, the impact-produced plasma can have deleterious effects on spacecraft electronics by providing a new current path, triggering an electrostatic discharge, causing electromagnetic interference, or generating an electromagnetic pulse. Multi-physics simulations of plasma production from hypervelocity impacts are presented. These simulations incorporate elasticity and plasticity of the solid target, phase change and plasma formation, and non-ideal plasma physics due to the high density and low temperature of the plasma. A smoothed particle hydrodynamics method is used to perform a continuum dynamics simulation with these additional physics. By examining a series of hypervelocity impacts, basic properties of the impact produced plasma plume (density, temperature, expansion speed, charge state) are determined for impactor speeds between 10 and 72 km/s. For a large range of higher impact speeds (30–72 km/s), we find the temperature is unvarying at 2.5 eV. We also find that the plasma plume is weakly ionized for impact speeds less than 14 km/s and fully ionized for impact speeds greater than 20 km/s, independent of impactor mass. This is the same velocity threshold for the detection of RF emission in recent

  3. Additions to compact heat exchanger technology: Jet impingement cooling & flow & heat transfer in metal foam-fins

    NASA Astrophysics Data System (ADS)

    Onstad, Andrew J.

    Compact heat exchangers have been designed following the same basic methodology for over fifty years. However, with the present emphasis on energy efficiency and light weight of prime movers there is increasing demand for completely new heat exchangers. Moreover, new materials and mesoscale fabrication technologies offer the possibility of significantly improving heat exchanger performance over conventional designs. This work involves fundamental flow and heat transfer experimentation to explore two new heat exchange systems: in Part I, large arrays of impinging jets with local extraction and in Part II, metal foams used as fins. Jet impingement cooling is widely used in applications ranging from paper manufacturing to the cooling of gas turbine blades because of the very high local heat transfer coefficients that are possible. While the use of single jet impingement results in non-uniform cooling, increased and more uniform mean heat transfer coefficients may be attained by dividing the total cooling flow among an array of smaller jets. Unfortunately, when the spent fluid from the array's central jets interact with the outer jets, the overall mean heat transfer coefficient is reduced. This problem can be alleviated by locally extracting the spent fluid before it is able to interact with the surrounding jets. An experimental investigation was carried out on a compact impingement array (Xn/Djet = 2.34) utilizing local extraction of the spent fluid (Aspent/Ajet = 2.23) from the jet exit plane. Spatially resolved measurements of the mean velocity field within the array were carried out at jet Reynolds numbers of 2300 and 5300 by magnetic resonance velocimetry, MRV. The geometry provided for a smooth transition from the jet to the target surface and out through the extraction holes without obvious flow recirculation. Mean Nusselt number measurements were also carried out for a Reynolds number range of 2000 to 10,000. The Nusselt number was found to increase with the

  4. Thermal Interaction Between Molten Metal and Sodium: Examination of the Fragmentation Mechanism of Molten Jet

    SciTech Connect

    Satoshi Nishimura; Izumi Kinshita; Nobuyuki Ueda; Ken-ichiro Sugiyama; Ryohei Okada

    2002-07-01

    In order to clarify the mechanism of thermal fragmentation of a molten jet dropped into a sodium pool at instantaneous contact interface temperatures below its freezing point, a basic experiment was carried out using molten copper and sodium. Copper was melted in a crucible with an electrical heater and was dropped through a short nozzle into a sodium pool, in the form of a jet column. Thermal fragmentation originating inside the molten copper jet with a solid crust was clearly observed in all runs. It is verified that a small quantity of sodium, which is locally entrained inside the molten jet due to the organized motion between the molten jet and sodium, is vaporized by the sensible heat and the latent heat of molten copper, and the high internal pressure causes the molten jet with a solid crust to fragment. It is also concluded that the thermal fragmentation is more dominant than the hydrodynamic fragmentation, in the present range of Weber number and superheating of molten jet. Furthermore, it can be explained that the thermal fragmentation caused by the molten copper jet - sodium interaction is severer than that caused by the molten uranium alloy jet - sodium interaction, which was reported by Gabor et al., because the latent heat and the thermal diffusivity of molten copper, which are the physical properties that dominate the degree of fragmentation, are much higher than those of molten uranium alloy jets. (authors)

  5. Maximizing power dissipation by impurity seeding on JET with metal plasma facing components

    NASA Astrophysics Data System (ADS)

    Wischmeier, Marco; Huber, Alexander; Lowry, Christopher; Maggi, Costanza; Reinke, Matthew; JET contributors Team

    2015-11-01

    A reactor such as DEMO will operate at considerably higher total heating power even when compared to ITER. This will require mitigating a much higher power flux density in the Scrape-Off Layer. A highly detached divertor will be required for maximizing the lifetime of the eroding plasma facing components, PFCs, in the divertor as well as for operating within the engineering limits expected for the power handling components. A dissipation of ~ 95% of the total heating power will be needed, with more than 70% being radiation on closed field lines. On JET with metal PFCs highly radiative conditions with N2, Ne, both combined and Ar as radiators were approached in H-mode plasmas. For all seeding species radiative power fractions larger than 70% were achieved under stable discharge conditions with a concentration of the radiation in the X-point region. Detachment along both divertor plates was complete. A degradation of the pedestal profile was compensated by steeper core profiles. See the Appendix of F. Romanelli et al., 25th FEC 2014, Russia, Supported by EUROfusion No 633053.

  6. Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

    NASA Astrophysics Data System (ADS)

    Mohan, Arun Ram

    Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor

  7. Hypervelocity Impact of Explosive Transfer Lines

    NASA Technical Reports Server (NTRS)

    Bjorkman, Michael D.; Christiansen, Eric L.

    2012-01-01

    Hypervelocity impact tests of 2.5 grains per foot flexible confined detonating chord (FCDC) shielded by a 1 mm thick 2024-T3 aluminum alloy bumper standing off 51 mm from the FCDC were performed. Testing showed that a 6 mm diameter 2017-T4 aluminum alloy ball impacting the bumper at 6.97 km/s and 45 degrees impact angle initiated the FCDC. However, impact by the same diameter and speed ball at 0 degrees angle of impact did not initiate the FCDC. Furthermore, impact at 45 degrees and the same speed by a slightly smaller diameter ball (5.8 mm diameter) also did not initiate the FCDC.

  8. Hypervelocity impact calculations using CTH: Case studies

    SciTech Connect

    Trucano, T.G.; McGlaun, J.M.

    1989-01-01

    In this paper, we discuss the application of CTH, a multi-dimensional Eulerian shock wave physics code, by discussing its application to hypervelocity impact problems. CTH is heavily used for this and other types of applications. We will not attempt to provide a broad discussion of examples and capabilities. Rather, we choose to focus on certain features of CTH that are of interest in gaining understanding of some of the more delicate issues of numerical impact simulations. 14 refs., 15 figs., 1 tab.

  9. ALE advantage in hypervelocity impact calculations

    SciTech Connect

    Gerassimenko, M.; Rathkopf, J.

    1998-10-01

    The ALE3D code is used to model experiments relevant to hypervelocity impact lethality, carried out in the 4-5 km/s velocity range. The code is run in the Eulerian and ALE modes. Zoning in the calculations is refined beyond the level found in most lethality calculations, but still short of convergence. The level of zoning refinement that produces equivalent results in uniformly zoned Eulerian calculations and ALE ones utilizing specialized zoning, weighting and relaxation techniques is established. It takes 11 times fewer zones and about 60% as many cycles when ALE capabilities are used. Calculations are compared to experimental results.

  10. Railgun rail gouging by hypervelocity sliding contact

    SciTech Connect

    Barker, L.M.; Trucano, T.G. ); Susoeff, A.R. )

    1989-01-01

    A description is given of a recently resolved mechanisms of gouging which occurs during hypervelocity sliding contact between two materials. A parameter study based on computer modeling of the gouging mechanism is presented in which gouging velocity thresholds are determined for several combinations of sliding materials. Materials which can gouge each other are found to do so only within a certain range of velocities. Related calculations of gaseous material ahead of railgun projectiles are also presented. Gun bore gouging experience with the Lawrence Livermore National Laboratory railgun project is reviewed.

  11. Railgun rail gouging by hypervelocity sliding contact

    SciTech Connect

    Barker, L.M.; Trucano, T.G.; Susoeff, A.R.

    1988-01-01

    A description is given of a recently resolved mechanism of gouging which occurs during hypervelocity sliding contact between two materials. A parameter study based on computer modelling of the gouging mechanism is presented in which gouging velocity thresholds are determined for several combinations of sliding materials. Materials which can gouge each other are found to do so only within a certain range of velocities. Related calculations of gaseous material ahead of railgun projectiles are also presented. Gun bore gouging experience with the Lawrence Livermore National Laboratory railgun project is reviewed.

  12. Breakup of metal jets penetrating a volatile liquid. Final report, October 1, 1991--February 28, 1993

    SciTech Connect

    Schneider, J.P.

    1995-07-01

    In a loss of coolant accident, the core may become uncovered, causing the fuel pins to melt. The molten fuel would pour onto the plenum and collect on the reactor pressure vessel (RPV) lower head. The RPV internal structure includes one or more perforated plates in the lower plenum which would divide the molten fuel into small diameter streams or jets, which would break up as they penetrate the coolant in the lower plenum. The breakup of these jets would occur in two phases, each dominated by a distinct fragmentation mechanism. As a fuel jet first penetrates the coolant, a stagnation flow develops at its leading edge, causing the column to spread radially and eject molten fuel into the coolant. The jet fluid in the column is fragmented by pressure fluctuations due to the jet/ambient fluid relative motion, so that a steady jet is reduced to a field of falling drops below a critical depth called the breakup length. The present work includes analyses yielding simple correlations for jet breakup length and jet leading edge penetration.

  13. Modelling of plasma-edge and plasma-wall interaction physics at JET with the metallic first-wall

    NASA Astrophysics Data System (ADS)

    Wiesen, S.; Groth, M.; Brezinsek, S.; Wischmeier, M.; contributors, JET

    2016-02-01

    An overview is given on the recent progress on edge modelling activities for the JET ITER-like wall using the computational tools like the SOLPS or EDGE2D-EIRENE code. The validation process of these codes on JET with its metallic plasma-facing components is an important step towards predictive studies for ITER and DEMO in relevant divertor operational conditions, i.e., for detached, radiating divertors. With increased quantitative credibility in such codes more reliable input to plasma-wall and plasma-material codes can be warranted, which in turn results in more realistic and physically sound estimates of the life-time expectations and performance of a Be first-wall and a W-divertor, the same materials configuration foreseen for ITER. A brief review is given on the recent achievements in the plasma-wall interaction and material migration studies. Finally, a short summary is given on the availability and development of integrated codes to assess the performance of an JET-ILW baseline scenario also in view of the preparation for a JET DT-campaign.

  14. Metal Foam Shields

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.

    2006-01-01

    This paper compares the ballistic performance of metallic foam sandwich structures with honeycomb structures. Honeycomb sandwich structures, consisting of metallic or composite facesheets and honeycomb cores, are often used in spacecraft construction due to their light-weight and structural stiffness. Honeycomb panels, however, are considered rather poor candidates for protection from micrometeoroid orbital debris (MMOD) particles because the honeycomb channels the debris cloud from MMOD impacts on outer facesheet causing a concentrated load on the second facesheet. Sandwich structures with light-weight, open-cell metallic cores and metal or composite facesheets provide improved MMOD protection because channeling does not occur and because the core is more effective at disrupting hypervelocity impacts then honeycomb. This paper describes hypervelocity impact tests on metallic foam sandwich structures (aluminum and titanium) with metallic facesheets, compare them to equivalent mass and thickness honeycomb panels, based on the results of hypervelocity impact tests.

  15. Hypervelocity Dust Injection for Plasma Diagnostic Applications

    NASA Astrophysics Data System (ADS)

    Ticos, Catalin

    2005-10-01

    Hypervelocity micron-size dust grain injection was proposed for high-temperature magnetized plasma diagnosis. Multiple dust grains are launched simultaneously into high temperature plasmas at several km/s or more. The hypervelocity dust grains are ablated by the electron and ion fluxes. Fast imaging of the resulting luminous plumes attached to each grain is expected to yield local magnetic field vectors. Combination of multiple local magnetic field vectors reproduces 2D or even 3D maps of the internal magnetic field topology. Key features of HDI are: (1) a high spatial resolution, due to a relatively small transverse size of the elongated tail, and (2) a small perturbation level, as the dust grains introduce negligible number of particles compared to the plasma particle inventory. The latter advantage, however, could be seriously compromised if the gas load from the accelerator has an unobstructed access to the diagnosed plasma. Construction of a HDI diagnostic for National Spherical Torus Experiment (NSTX), which includes a coaxial plasma gun for dust grain acceleration, is underway. Hydrogen and deuterium gas discharges inside accelerator are created by a ˜ 1 mF capacitor bank pre-charged up to 10 kV. The diagnostic apparatus also comprises a dust dispenser for pre-loading the accelerator with dust grains, and an imaging system that has a high spatial and temporal resolution.

  16. Hypervelocity Impact Studies on Solar Cell Modules

    NASA Technical Reports Server (NTRS)

    Brandhorst, Henry W., Jr.; Best, Stevie R.

    2001-01-01

    Space environmental effects have caused severe problems as satellites move toward increased power and operating voltage levels. The greatest unknown, however, is the effect of high velocity micrometeoroid impacts on high voltage arrays (>200V). Understanding such impact phenomena is necessary for the design of future reliable, high voltage solar arrays, especially for Space Solar Power applications. Therefore, the objective of this work was to study the effect of hypervelocity impacts on high voltage solar arrays. Initially, state of the art, 18% efficient GaAs solar cell strings were targeted. The maximum bias voltage on a two-cell string was -200 V while the adjacent string was held at -140 V relative to the plasma potential. A hollow cathode device provided the plasma. Soda lime glass particles 40-120 micrometers in diameter were accelerated in the Hypervelocity Impact Facility to velocities as high as 11.6 km/sec. Coordinates and velocity were obtained for each of the approximately 40 particle impact sites on each shot. Arcing did occur, and both discharging and recharging of arcs between the two strings was observed. The recharging phenomena appeared to stop at approximately 66V string differential. No arcing was observed at 400 V on concentrator cell modules for the Stretched Lens Array.

  17. Subsurface Deformation of Nonporous Rocks Induced by Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Winkler, R.; Poelchau, M. H.; Michalski, C.; Kenkmann, T.

    2015-09-01

    Two hypervelocity impact experiments into quarzite and marble were conducted under similar impact condition. Both experiments show tensile failure; quarzite developed zones of strong grain size reduction, while marble shows intragranular fracturing.

  18. Ejecta Dynamics during Hypervelocity Impacts into Dry and Wet Sandstone

    NASA Astrophysics Data System (ADS)

    Hoerth, T.; Schäfer, F.; Thoma, K.; Poelchau, M.; Kenkmann, T.; Deutsch, A.

    2011-03-01

    Hypervelocity impact experiments into dry and water saturated porous Seeberger sandstone were conducted at the two-stage light gas accelerator at the Ernst-Mach-Institute (EMI) and the ejecta dynamics were analyzed.

  19. The XLLGG — A Hypervelocity Launcher for Impact Cratering Research

    NASA Astrophysics Data System (ADS)

    Lexow, B.; Bückle, A.; Wickert, M.; Hiermaier, S.

    2015-09-01

    Hypervelocity launchers are used to accelerate projectiles that simulate impacting meteoroids or asteroids. The XLLGG (eXtra Large Light Gas Gun) at the EMI (Ernst-Mach-Institute) was used within the MEMIN program.

  20. NASA White Sands Test Facility Remote Hypervelocity Test Laboratory

    NASA Video Gallery

    Tour the NASA White Sands Test Facility's Remote Hypervelocity Test Laboratory in Las Cruces, New Mexico. To learn more about White Sands Test Facility, go to http://www.nasa.gov/centers/wstf/home/...

  1. Thrust Enhancement in Hypervelocity Nozzles by Chemical Catalysis

    NASA Technical Reports Server (NTRS)

    Singh, D. J.; Carpenter, Mark H.; Drummond, J. P.

    1997-01-01

    In the hypersonic flight regime, the air-breathing supersonic combustion ramjet (scramjet) has been shown to be a viable propulsion system. The current designs of scramjet engines provide performance benefits only up to a Mach number of 14. Performance losses increase rapidly as the Mach number increases. To extend the applicability of scram'jets beyond Mach 14, research is being conducted in the area of inlet and wave drag reduction, skin-friction and heat-transfer reduction, nozzle loss minimization, low-loss mixing, and combustion enhancement. For high Mach number applications, hydrogen is the obvious fuel choice because of its high energy content per unit mass in comparison with conventional fuels. These flight conditions require engines to operate at supersonic internal velocities, high combustor temperatures, and low static pressures. The high static temperature condition enhances the production of radicals such as H and OH, and the low-pressure condition slows the reaction rates, particularly the recombination reactions. High-temperature and low-pressure constraints, in combination with a small residence time, result in a radical-rich exhaust gas mixture exiting the combustor. At high Mach number conditions (due to low residence time), H and OH do not have enough time to recombine ; thus, a significant amount of energy is lost as these high-energy free radical are exhausted. The objective of the present study is to conduct a flowfield analysis for a typical nozzle geometry for NASP-type vehicle to assess for thrust enhancement in hypervelocity nozzles by substituting small amount of phosphine for hydrogen.

  2. Thermal softening of metallic shaped-charge jets formed by the collapse of shaped-charge liners in the presence of a magnetic field

    NASA Astrophysics Data System (ADS)

    Fedorov, S. V.

    2016-05-01

    This paper presents an analysis of the possibility of increasing the ultimate stretching and penetration capability of metallic shaped-charge jets in the presence of an axial magnetic field in the shaped-charge liner due to heating and thermal softening of the jet material as a result of a sharp increase in the magnetic-field induction in the jet formation region upon liner collapse. This process is studied by numerical simulation in a quasi-two-dimensional formulation taking into account the inertial stretching of the conductive rigid-plastic rod in the presence of a longitudinal magnetic field in it.

  3. Hypervelocity impact survivability experiments for carbonaceous impactors

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Becker, Luann; Bada, Jeffrey; Macklin, John; Radicatidibrozolo, Filippo; Fleming, R. H.; Erlichman, Jozef

    1993-01-01

    We performed a series of hypervelocity impact experiments using carbon-bearing impactors (diamond, graphite, fullerenes, phthalic acid crystals, and Murchison meteorite) into Al plate at velocities between 4.2 and 6.1 km/s. These tests were made to do the following: (1) determine the survivability of carbon forms and organize molecules in low hypervelocity impact; (2) characterize carbonaceous impactor residues; and (3) determine whether or not fullerenes could form from carbonaceous impactors, under our experimental conditions, or survive as impactors. An analytical protocol of field emission SEM imagery, SEM-EDX, laser Raman spectroscopy, single and 2-stage laser mass spectrometry, and laser induced fluorescence (LIF) found the following: (1) diamonds did not survive impact at 4.8 km/s, but were transformed into various forms of disordered graphite; (2) intact, well-ordered graphite impactors did survive impact at 5.9 km/sec, but were only found in the crater bottom centers; the degree of impact-induced disorder in the graphite increases outward (walls, rims, ejecta); (3) phthalic acid crystals were destroyed on impact (at 4.2 km/s, although a large proportion of phthalic acid molecules did survive impact); (4) fullerenes did not form as products of carbonaceous impactors (5.9 - 6.1 km/s, fullerene impactor molecules mostly survived impact at 5.9 km/s; and (5) two Murchison meteorite samples (launched at 4.8 and 5.9 km/s) show preservation of some higher mass polycyclic aromatic hydrocarbons (PAHs) compared with the non-impacted sample. Each impactor type shows unique impactor residue morphologies produced at a given impact velocity. An expanded methodology is presented to announce relatively new analytical techniques together with innovative modifications to other methods that can be used to characterize small impact residues in LDEF craters, in addition to other acquired extraterrestrial samples.

  4. Theory and Observations of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Ginsburg, Idan; Loeb, A.; Wegner, G. A.; Brown, W. R.; Perets, H.

    2013-01-01

    Since first discovered in 2005, stars ejected from the Milky Way, so-called hypervelocity stars (HVSs), have greatly increased our understanding of the kinematics and dynamics at the Galactic Center (GC). Using N-body simulations we show that an encounter between a binary star-system and the massive black hole (MBH) at the GC can result in the production of a HVS for one component of the binary, while the companion star remains in a tight orbit around the MBH. Such an encounter can also result in the coalescence of both stars in a highly-eccentric orbit around the MBH. These mechanisms may explain the suprising appearance of massive stars within 1'' of the GC. Continuing with our simulations, we find that the disruption of a triple system by the MBH can produce hypervelocity binaries. Such binaries may evolve into massive blue stragglers, while binaries captured by the MBH may be rejuvenated stars. Our simulations also predict that planets can be ejected from the GC at velocities approaching 5 percent the speed of light. Furthermore, HVSs can house planets that should be detectable as transits. The discovery of such a transit has important consequences for understanding planetary formation and evolution at the GC. We will also present photometry from 11 HVSs, taken February and May 2012, at the WIYN 3.5-meter and Hiltner 2.4-meter telescopes. Our photometry shows that many of the observed HVSs are likely slowly pulsating B stars, which constrains their nature and distance. Ongoing surveys for HVSs, including collaboration with the Australian Sky Mapper survey, as well as Hubble Space Telescope proper motion measurements promise to continue expanding our understanding of HVSs and consequently the dynamics within our galaxy.

  5. Hypervelocity atmospheric flight: Real gas flow fields

    NASA Technical Reports Server (NTRS)

    Howe, John T.

    1990-01-01

    Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that were reduced to a relatively compact set of equations of a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-averaged behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equation a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. For hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates, chemical nonequilibrium is considered and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

  6. Hypervelocity atmospheric flight: Real gas flow fields

    NASA Technical Reports Server (NTRS)

    Howe, John T.

    1989-01-01

    Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that have been reduced to a relatively compact set of equations in a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-average behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equations a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. Hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates chemical nonequilibrium is considered, and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

  7. Metal-mesh based transparent electrode on a 3-D curved surface by electrohydrodynamic jet printing

    NASA Astrophysics Data System (ADS)

    Seong, Baekhoon; Yoo, Hyunwoong; Dat Nguyen, Vu; Jang, Yonghee; Ryu, Changkook; Byun, Doyoung

    2014-09-01

    Invisible Ag mesh transparent electrodes (TEs), with a width of 7 μm, were prepared on a curved glass surface by electrohydrodynamic (EHD) jet printing. With a 100 μm pitch, the EHD jet printed the Ag mesh on the convex glass which had a sheet resistance of 1.49 Ω/□. The printing speed was 30 cm s-1 using Ag ink, which had a 10 000 cPs viscosity and a 70 wt% Ag nanoparticle concentration. We further showed the performance of a 3-D transparent heater using the Ag mesh transparent electrode. The EHD jet printed an invisible Ag grid transparent electrode with good electrical and optical properties with promising applications on printed optoelectronic devices.

  8. Removal of diamond-turning signatures on x-ray mandrels and metal optics by fluid-jet polishing

    NASA Astrophysics Data System (ADS)

    Beaucamp, A.; Freeman, R.; Morton, R.; Ponudurai, Karthik; Walker, D. D.

    2008-07-01

    This paper describes a major advance in the post-treatment of diamond-turned surfaces to remove repetitive micro-structure; a result which could have a major beneficial impact on fabrication of Walter-type X-ray mandrels, and metal mirrors. Diamond-turning is highly deterministic and versatile in producing axially-symmetric forms, and through fast-tool servos, non-axially symmetric, free-form and micro-structured surfaces. However, the fine turning marks left in the metal surface limit performance. In this paper, we describe how fluid-jet polishing under CNC control can be used to eliminate these structures, without significantly degrading the surface roughness or form produced by the prior turning operation.

  9. An investigation on co-axial water-jet assisted fiber laser cutting of metal sheets

    NASA Astrophysics Data System (ADS)

    Madhukar, Yuvraj K.; Mullick, Suvradip; Nath, Ashish K.

    2016-02-01

    Water assisted laser cutting has received significant attention in recent times with assurance of many advantages than conventional gas assisted laser cutting. A comparative study between co-axial water-jet and gas-jet assisted laser cutting of thin sheets of mild steel (MS) and titanium (Ti) by fiber laser is presented. Fiber laser (1.07 μm wavelength) was utilised because of its low absorption in water. The cut quality was evaluated in terms of average kerf, projected dross height, heat affected zone (HAZ) and cut surface roughness. It was observed that a broad range process parameter could produce consistent cut quality in MS. However, oxygen assisted cutting could produce better quality only with optimised parameters at high laser power and high cutting speed. In Ti cutting the water-jet assisted laser cutting performed better over the entire range of process parameters compared with gas assisted cutting. The specific energy, defined as the amount of laser energy required to remove unit volume of material was found more in case of water-jet assisted laser cutting process. It is mainly due to various losses associated with water assisted laser processing such as absorption of laser energy in water and scattering at the interaction zone.

  10. Capture of dusts from hypervelocity collision of planetary materials: Implication for dust size distribution in debris discs

    NASA Astrophysics Data System (ADS)

    Takasawa, Susumu; Nakamura, Akiko; Kadono, Toshihiko; Arakawa, Masahiko; Dohi, Hirotsugu; Seto, Yusuke; Maeda, Makoto; Shigemori, Keisuke; Hironaka, Yoichiro; Sakaiya, Tatsuhiro; Sano, Takayoshi; Watari, Takeshi; Fujioka, Shinsuke; Ohno, Sohsuke; Takeuchi, Taku; Sangen, Kazuyoshi

    2011-06-01

    In order to examine the size distribution of dust particles from collision of solid bodies, we conducted hypervelocity impact experiments. Sub-mm size metal spheres were accelerated to velocities from 9 to 61 km/s by laser ablation and were shot into rock targets. Dust particles were collected by aerogels and were analyzed by Electron Probe Micro Analyzer (EPMA). We derived the size distributions of ejecta ranging from five to tens of micron in diameter. The slope of cumulative ejecta size distribution was steeper than a purely collisional equilibrium distribution in a collision cascade. This suggests that a steep dust size distribution in a debris disc around an A5V star HD172555 can be due to a hypervelocity impact.

  11. NASA Ames Arc Jets and Range, Capabilities for Planetary Entry

    NASA Technical Reports Server (NTRS)

    Fretter, Ernest F.

    2005-01-01

    NASA is pursuing innovative technologies and concepts as part of America's Vision for Space Exploration. The rapidly emerging field of nanotechnology has led to new concepts for multipurpose shields to prevent catastrophic loss of vehicles and crew against the triple threats of aeroheating during atmospheric entry, radiation (Solar and galactic cosmic rays) and Micrometorid/Orbital Debris (MMOD) strikes. One proposed concept is the Thermal Radiation Impact Protection System (TRIPS) using carbon nanotubes, hydrogenated carbon nanotubes, and ceramic coatings as a multi-use TPS. The Thermophysics Facilities Branch of the Space Technology Division at NASA Ames Research Center provides testing services for the development and validation of the present and future concepts being developed by NASA and national and International research firms. The Branch operates two key facilities - the Range Complex and the Arc Jets. The Ranges include both the Ames Vertical Gun Range (AVGR) and the Hypervelocity Free Flight (HFF) gas guns best suited for MMOD investigations. Test coupons can be installed in the AVGR or HFF and subjected to particle impacts from glass or metal particles from micron to _ inch (6.35-mm) diameters and at velocities from 5 to 8 kilometers per second. The facility can record high-speed data on film and provide damage assessment for analysis by the Principle Investigator or Ames personnel. Damaged articles can be installed in the Arc Jet facility for further testing to quantify the effects of damage on the heat shield s performance upon entry into atmospheric environments.

  12. Endoscopic transluminal pancreatic necrosectomy using a self-expanding metal stent and high-flow water-jet system

    PubMed Central

    Hritz, István; Fejes, Roland; Székely, András; Székely, Iván; Horváth, László; Sárkány, Ágnes; Altorjay, Áron; Madácsy, László

    2013-01-01

    Walled-off pancreatic necrosis and a pancreatic abscess are the most severe complications of acute pancreatitis. Surgery in such critically ill patients is often associated with significant morbidity and mortality within the first few weeks after the onset of symptoms. Minimal invasive approaches with high success and low mortality rates are therefore of considerable interest. Endoscopic therapy has the potential to offer safe and effective alternative treatment. We report here on 3 consecutive patients with infected walled-off pancreatic necrosis and 1 patient with a pancreatic abscess who underwent direct endoscopic necrosectomy 19-21 d after the onset of acute pancreatitis. The infected pancreatic necrosis or abscess was punctured transluminally with a cystostome and, after balloon dilatation, a non-covered self-expanding biliary metal stent was placed into the necrotic cavity. Following stent deployment, a nasobiliary pigtail catheter was placed into the cavity to ensure continuous irrigation. After 5-7 d, the metal stent was removed endoscopically and the necrotic cavity was entered with a therapeutic gastroscope. Endoscopic debridement was performed via the simultaneous application of a high-flow water-jet system; using a flush knife, a Dormia basket, and hot biopsy forceps. The transluminal endotherapy was repeated 2-5 times daily during the next 10 d. Supportive care included parenteral antibiotics and jejunal feeding. All patients improved dramatically and with resolution of their septic conditions; 3 patients were completely cured without any further complications or the need for surgery. One patient died from a complication of prolonged ventilation severe bilateral pneumonia, not related to the endoscopic procedure. No procedure related complications were observed. Transluminal endoscopic necrosectomy with temporary application of a self-expanding metal stent and a high-flow water-jet system shows promise for enhancing the potential of this endoscopic

  13. Endoscopic transluminal pancreatic necrosectomy using a self-expanding metal stent and high-flow water-jet system.

    PubMed

    Hritz, István; Fejes, Roland; Székely, András; Székely, Iván; Horváth, László; Sárkány, Agnes; Altorjay, Aron; Madácsy, László

    2013-06-21

    Walled-off pancreatic necrosis and a pancreatic abscess are the most severe complications of acute pancreatitis. Surgery in such critically ill patients is often associated with significant morbidity and mortality within the first few weeks after the onset of symptoms. Minimal invasive approaches with high success and low mortality rates are therefore of considerable interest. Endoscopic therapy has the potential to offer safe and effective alternative treatment. We report here on 3 consecutive patients with infected walled-off pancreatic necrosis and 1 patient with a pancreatic abscess who underwent direct endoscopic necrosectomy 19-21 d after the onset of acute pancreatitis. The infected pancreatic necrosis or abscess was punctured transluminally with a cystostome and, after balloon dilatation, a non-covered self-expanding biliary metal stent was placed into the necrotic cavity. Following stent deployment, a nasobiliary pigtail catheter was placed into the cavity to ensure continuous irrigation. After 5-7 d, the metal stent was removed endoscopically and the necrotic cavity was entered with a therapeutic gastroscope. Endoscopic debridement was performed via the simultaneous application of a high-flow water-jet system; using a flush knife, a Dormia basket, and hot biopsy forceps. The transluminal endotherapy was repeated 2-5 times daily during the next 10 d. Supportive care included parenteral antibiotics and jejunal feeding. All patients improved dramatically and with resolution of their septic conditions; 3 patients were completely cured without any further complications or the need for surgery. One patient died from a complication of prolonged ventilation severe bilateral pneumonia, not related to the endoscopic procedure. No procedure related complications were observed. Transluminal endoscopic necrosectomy with temporary application of a self-expanding metal stent and a high-flow water-jet system shows promise for enhancing the potential of this endoscopic

  14. Emission FTIR analyses of thin microscopic patches of jet fuel residues deposited on heated metal surfaces

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.; Vogel, P.

    1986-01-01

    The relationship of fuel stability to fuel composition and the development of mechanisms for deposit formation were investigated. Fuel deposits reduce heat transfer efficiency and increase resistance to fuel flow and are highly detrimental to aircraft performance. Infrared emission Fourier transform spectroscopy was chosen as the primary method of analysis because it was sensitive enough to be used in-situ on tiny patches of monolayers or of only a few molecular layers of deposits which generally proved completely insoluble in any nondestructive solvents. Deposits of four base fuels were compared; dodecane, a dodecane/tetralin blend, commercial Jet A fuel, and a broadened-properties jet fuel particularly rich in polynuclear aromatics. Every fuel in turn was provided with and without small additions of such additives as thiophene, furan, pyrrole, and copper and iron naphthenates.

  15. Meteoroids and space debris hypervelocity impact penetrations in LDEF map foils compared with hydrocode simulations

    NASA Astrophysics Data System (ADS)

    Tanner, W. G.; McDonnell, J. A. M.; Yano, H.; Fitzgerald, H. J.; Gardner, D. J.

    The continued analyses of penetrating impacts on MAP foils of Aluminium and Brass have produced data for several LDEF faces, i.e., Space, West, and East. These data have immediate bearing on the interpretation and design of devices to detect the penetration of a thin metallic film by a dust grain which have been tested both in the laboratory and in space. A crucial component of the analysis has been the theoretical calculation utilizing CTH, a Sandia National Laboratory Hydrodynamic computer code /1/ to assess the parameters of the hypervelocity penetration event. In particular theoretical hydrodynamic calculations have been conducted to simulate the hypervelocity impact event where various cosmic dust grain candidates, e.g., density = 0.998, 2.700, 7.870 (gm/cm^3), and velocities, i.e., 7 - 16 km/s, have been utilized to reproduce the events. Theoretical analyses of hypervelocity impact events will be reported which span an extensive matrix of values for velocity, density and size. Through a comparison between LDEF MAP foil measurements and CTH hydrocode calculations these analyses will provide an interpretation of the most critical parameters measured for space returned materials, i.e., for thin films, the diameter of the penetration hole, D_h, and for semi-infinite targets, the depth-to-diameter ratio of craters, D_c/T_c. An immediate consequence of a comparison of CTH calculations with space exposed materials will be an enhancement of the coherent model developed by UKC-USS researchers to describe penetration dynamics associated with LDEF MAP foils.

  16. Simple light gas guns for hypervelocity studies

    SciTech Connect

    Combs, S.K.; Haselton, H.H.; Milora, S.L.

    1990-01-01

    Two-stage light guns are used extensively in hypervelocity research. The applications of this technology include impact studies and special materials development. Oak Ridge National Laboratory (ORNL) has developed two-stage guns that accelerate small projectiles (4-mm nominal diameter) to velocities of up to {approx}5 km/s. These guns are relatively small and simple (thus, easy to operate), allowing a significant number of test shots to be carried out and data accumulated in a short time. Materials that have been used for projectiles include plastics, frozen isotopes of hydrogen, and lithium hydride. One gun has been used to demonstrate repetitive operation at a rate of 0.7 Hz; and, with a few design improvements, it appears capable of performing at firing frequencies of 1--2 Hz. A schematic of ORNL two-stage device is shown below. Unlike most such devices, no rupture disks are used. Instead, a fast valve (high-flow type) initiates the acceleration process in the first stage. Projectiles can be loaded into the gun breech via the slide mechanism; this action has been automated which allows repetitive firing. Alternatively, the device is equipped with pipe gun'' apparatus in which gas can be frozen in situ in the gun barrel to form the projectile. This equipment operates with high reliability and is well suited for small-scale testing at high velocity. 17 refs., 6 figs., 2 tabs.

  17. Orbiter Window Hypervelocity Impact Strength Evaluation

    NASA Technical Reports Server (NTRS)

    Estes, Lynda R.

    2011-01-01

    When the Space Shuttle Orbiter incurs damage on its windowpane during flight from particles traveling at hypervelocity speeds, it produces a distinctive damage that reduces the overall strength of the pane. This damage has the potential to increase the risk associated with a safe return to Earth. Engineers at Boeing and NASA/JSC are called to Mission Control to evaluate the damage and provide an assessment on the risk to the crew. Historically, damages like these were categorized as "accepted risk" associated with manned spaceflight, and as long as the glass was intact, engineers gave a "go ahead" for entry for the Orbiter. Since the Columbia accident, managers have given more scrutiny to these assessments, and this has caused the Orbiter window engineers to capitalize on new methods of assessments for these damages. This presentation will describe the original methodology that was used to asses the damages, and introduce a philosophy new to the Shuttle program for assessing structural damage, reliability/risk-based engineering. The presentation will also present a new, recently adopted method for assessing the damage and providing management with a reasonable assessment on the realities of the risk to the crew and vehicle for return.

  18. Electromagnetic Pulses Generated by Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Close, S.

    2011-12-01

    Hypervelocity impacts on spacecraft are known to cause mechanical damage, but their electrical effect on spacecraft systems are not well-characterized. We present a theory to explain plasma production and subsequent electric fields occurring when a meteoroid or piece of space debris strikes a spacecraft, ionizing itself and part of the spacecraft. This plasma, with a charge separation commensurate with different species mobilities, can produce a strong electromagnetic pulse (EMP), potentially causing catastrophic damage if the impact is relatively near an area with low shielding or an open umbilical. The plasma density, and hence plasma frequency, sweeps down as the plasma expands ballistically into the vacuum causing a chirp. Subsequent plasma oscillations can also emit significant power and may be responsible for many reported satellite anomalies. The presented theory discusses both a dust-free plasma expansion with coherent electron oscillation and a dusty plasma expansion with macroscopic charge separation. We show that significant RF can be emitted from frequencies ranging from VLF through S-band.

  19. Hydrocode modelling of hypervelocity impacts on ice

    NASA Astrophysics Data System (ADS)

    Fendyke, S.; Price, M. C.; Burchell, M. J.

    2013-08-01

    Experimental data are now widely available for the size of craters resulting from hypervelocity impacts of millimetre scale projectiles onto water ice targets. At such size scales the bowl shaped crater formed in ductile materials, or in larger scale impacts, is here surrounded by a large spallation zone due to the brittle nature of the ice. Modelling of these impacts therefore has to take account of this spallation. Here we used the iSALE2 hydrocode to simulate such impacts and compared the results to experimental data. We found that it was possible to reproduce the experimental data over a range of speeds (1-7 km s-1) for aluminium and copper projectiles. Initially, to reproduce the large spallation regions around the craters it was assumed that above a certain degree of damage, material was removed by spallation. However this simple one-parameter model failed to model the crater depth adequately. Accordingly, to obtain the best agreement of the simulations with the experimental data, a two-step ice strength was introduced, whereby above a critical amount of damage (0.95), the yield strength reduced from 1 MPa (intact) to 70 kPa (damaged). As a result, experimental data for crater depth and diameter and the results of the simulations agree to within 6% for diameter and 5% for depth over the impact energy range used in the experiments (1-240 J).

  20. Further investigations of oblique hypervelocity impact phenomena

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1988-01-01

    The results of a continuing investigation of the phenomena associated with the oblique hypervelocity impact of spherical projectiles onto multi-sheet aluminum structures are described. A series of equations that quantitatively describes these phenomena is obtained through a regression of experimental data. These equations characterize observed ricoshet and penetration damage phenomena in a multi-sheet structure as functions of the geometric parameters of the structure and the diameter, obliquity, and velocity of the impacting projectile. Crater damage observed on the ricochet witness plates is used to determine the sizes and speeds of the ricochet debris particles that caused the damage. It is shown that, in general, the most damaging ricochet debris particle is approximately 0.25 cm (0.10 in) in diameter and travels at the speed of approximately 2.1 km/sec (6,890 ft/sec). The equations necessary for the design of shielding panels that will protect external systems from such ricochet debris damage are also developed. The dimensions of these shielding panels are shown to be strongly dependent on their inclination and on their circumferential distribution around the spacecraft. It is concluded that obliquity effects of high-speed impacts must be considered in the design of any structure exposed to the meteoroid and space debris environment.

  1. Testing of a Plasmadynamic Hypervelocity Dust Accelerator

    NASA Astrophysics Data System (ADS)

    Ticos, Catalin M.; Wang, Zhehui; Dorf, Leonid A.; Wurden, G. A.

    2006-10-01

    A plasmadynamic accelerator for microparticles (or dust grains) has been designed, built and tested at Los Alamos National laboratory. The dust grains are expected to be accelerated to hypervelocities on the order of 1-30 km/s, depending on their size. The key components of the plasmadynamic accelerator are a coaxial plasma gun operated at 10 kV, a dust dispenser activated by a piezoelectric transducer, and power and remote-control systems. The coaxial plasma gun produces a high density (10^18 cm-3) and low temperature (˜ 1 eV) plasma in deuterium ejected by J x B forces, which provides drag on the dust particles in its path. Carbon dust particles will be used, with diameters from 1 to 50 μm. The plasma parameters produced in the coaxial gun are presented and their implication to dust acceleration is discussed. High speed dust will be injected in the National Spherical Torus Experiment to measure the pitch angle of magnetic field lines.

  2. Projectile development for railguns using hypervelocity preacceleration

    NASA Astrophysics Data System (ADS)

    Susoeff, A. R.; Hawke, R. S.; Ang, J. A.; Asay, J. R.; Hall, C. A.; Konrad, C. H.; Sauve, G. L.

    1992-03-01

    The STARFIRE Project is a joint Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories (SNL) effort to achieve hypervelocity projectile launches up to 15 km/s. The apparatus used to achieve this goal is a three stage acceleration system made up of a two-stage light-gas gun (2SLGG) coupled to a railgun. The 2SLGG is used as a preaccelerator capable of injecting 2 gram projectiles at velocities of 6 km/s or more. Projectiles used in this environment are subject to many conditions. Some of these which effect projectile design include acceleration loading, structural response, barrel condition and alignment. Development of a projectile to satisfy the programmatic requirements is underway. This report covers the evolution of design and fabrication for railgun projectiles from previous experimentation at LLNL to the replenished plasma armature and projectile now used on STARFIRE. Projectile design, development and fabrication methods which use off-the-shelf materials and standard techniques to meet the operational criteria of the experimental program are discussed in this paper. Initial work involving the design and fabrication of skirted projectiles, which are expected to further reduce interaction phenomena between the plasma armature and railgun barrel, is also described.

  3. Projectile development for railguns using hypervelocity preacceleration

    SciTech Connect

    Susoeff, A.R.; Hawke, R.S.; Sauve, G.L.; Konrad, C.H.; Hickman, R.J.

    1991-02-01

    The STARFIRE Project is a joint Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories (SNL) effort to achieve hypervelocity projectile launches up to 15 km/s. The apparatus used to achieve this goal is a three stage acceleration system made up of a two-stage light-gas gun (2SLGG) is used as a preaccelerator capable of injecting 2 gram projectiles at velocities of 6 km/s or more. Projectiles used in this environment are subject to many conditions. Some of these which effect projectile design include: acceleration loading, structural response, barrel condition and alignment. Development of a projectile to satisfy the programmatic requirements is underway. This report covers the evolution of design and fabrication for railgun projectiles from previous experience at LLNL to the replenished plasma armature and projectile now used on STARFIRE. Projectile design, development and fabrication methods which use off-the-shelf materials and standard techniques to meet the operational criteria of the experimental program are discussed in this paper. Initial work involving the design and fabrication of skirted projectiles, which are expected to further reduce interaction phenomena between the plasma armature and railgun barrel, is also described.

  4. Projectile development for railguns using hypervelocity preacceleration

    SciTech Connect

    Susoeff, A.R.; Hawke, R.S. ); Ang, J.A.; Asay, J.R.; Hall, C.A.; Konrad, C.H. ); Sauve, G.L. . Rocky Flats Plant); Hickman, R.J. )

    1992-03-20

    The STARFIRE Project is a joint Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories (SNL) effort to achieve hypervelocity projectile launches up to 15 km/s. The apparatus used to achieve this goal is a three stage acceleration system made up of a two-stage light-gas gun (2SLGG) coupled to a railgun. The 2SLGG is used as a preaccelerator capable of injecting 2 gram projectiles at velocities of 6 km/s or more. Projectiles used in this environment are subject to many conditions. Some of these which effect projectile design include: acceleration loading, structural response, barrel condition and alignment. Development of a projectile to satisfy the programmatic requirements is underway. This report covers the evolution of design and fabrication for railgun projectiles from previous experiment at LLNL to the replenished plasma armature and projectile now used on STARFIRE. Projectile design, development and fabrication methods which use off-the-shelf materials and standard techniques to meet the operational criteria of the experimental program are discussed in this paper. Initial work involving the design and fabrication of skirted projectiles, which are expected to further reduce interaction phenomena between the plasma armature and railgun barrel, is also described.

  5. Calculations supporting HyperVelocity Launcher development

    SciTech Connect

    Trucano, T.G.; Chhabildas, L.C.

    1993-08-01

    Sandia National Laboratories has developed a HyperVelocity Launcher (also referred to as HVL) in which a thin flier plate (nominally 1 mm thick) is launched to velocities in excess of 12 km/s. The length to diameter ratio of these launched flier plates varies from 0.02 to 0.06. The launch technique is based upon using structured, time-dependant, high-pressure, high-acceleration pulses to drive the flier plates. Such pulses are achieved by using a graded-density material to impact a stationary flier. A computational and experimental program at Sandia seeks to extend this technique to allow launching thick plates whose length-to-diameter ratio is 10 to 20 times larger than thin plates. Hydrodynamic codes are used to design modifications to the basic technique. The authors have controlled and used these effects to successfully launch a chunk-flier, consisting of 0.33 gm of titanium alloy, 0.3 cm thick by 0.6 cm in diameter, to a velocity of 10.2 km/s. This is the largest chunky size ever launched at this velocity from a gas gun configuration.

  6. Characteristics of plasma generated by hypervelocity impact

    SciTech Connect

    Song, Weidong; Li, Jianqiao; Ning, Jianguo

    2013-09-15

    The characteristics of plasma generated by hypervelocity impact were studied through both theoretical analysis and numerical simulation. Based on thermodynamics and statistical physics, a thermal ionization model was proposed to explore the relationships of ionization degree and plasma conductivity to temperature with consideration of the velocity distribution law in the thermodynamic equilibrium state. In order to derive the temperature, internal energy, and density of the plasma generated by the impact for the above relationships, a 3-D model for the impact of an aluminum spherical projectile on an aluminum target was established and five cases with different impact angles were numerically simulated. Then, the temperature calculated from the internal energy and the Thomas Fermi (TF) model, the internal energy and the density of the plasma were put into the function of the ionization degree to study the characteristics of plasma. Finally, based on the experimental data, a good agreement was obtained between the theoretical predictions and the experimental results, and the feasibility of this theoretical model was verified.

  7. Morphology correlation of craters formed by hypervelocity impacts

    NASA Technical Reports Server (NTRS)

    Crawford, Gary D.; Rose, M. Frank; Zee, Ralph H.

    1993-01-01

    Dust-sized olivine particles were fired at a copper plate using the Space Power Institute hypervelocity facility, simulating micrometeoroid damage from natural debris to spacecraft in low-Earth orbit (LEO). Techniques were developed for measuring crater volume, particle volume, and particle velocity, with the particle velocities ranging from 5.6 to 8.7 km/s. A roughly linear correlation was found between crater volume and particle energy which suggested that micrometeoroids follow standard hypervelocity relationships. The residual debris analysis showed that for olivine impacts of up to 8.7 km/s, particle residue is found in the crater. By using the Space Power Institute hypervelocity facility, micrometeoroid damage to satellites can be accurately modeled.

  8. Penetration and ricochet phenomena in oblique hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Taylor, Roy A.

    1989-01-01

    An experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectile on multisheet aluminum structures is described. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the meteoroid and space debris environment.

  9. In-flight detection of small hypervelocity particles.

    NASA Technical Reports Server (NTRS)

    Robinson, D. M.; Goad, J. H.; Chu, W. P.

    1973-01-01

    A technique is described in which small (25-micron) hypervelocity (10-km/sec) in-flight particles can be detected in the presence of high background noise. The system is based on a spatial filtering principle whereby spurious noise effects are reduced by use of a beam stop in the entrance aperture of the system and a bandpass filter in the transform plane. A theoretical analysis of the system is presented, and some experimental results are obtained by detecting in-flight hypervelocity particles generated by an exploding lithium wire electrothermal accelerator.

  10. Hypervelocity impact cratering - A catastrophic terrestrial geologic process

    NASA Astrophysics Data System (ADS)

    Grieve, Richard A. F.

    It is possible to infer a 5.4 x 10 to the 15th/sq km per year terrestrial impact cratering rate for hypervelocity impact structures with diameters greater than 20 km. These craters often contain such shock-metamorphic effects as shatter cones, tectosilicate microscopic planar features, diapleptic solid-state glasses, and impact melting. Impact melt rocks may contain siderophile anomalies indicative of siderophile material admixtures. Hypervelocity impacts have gained recognition as catastrophes with potentially severe biological effects; the cratering record is such as to suggest that the earth may be subjected to periodic cometary showers.

  11. Burst Pressure Failure of Titanium Tanks Damaged by Secondary Plumes from Hypervelocity Impacts on Aluminum Shields

    NASA Astrophysics Data System (ADS)

    Nahra, Henry; Ghosn, Louis; Christiansen, Eric; Davis, B. Alan; Keddy, Christopher; Rodriguez, Karen; Miller, Joshua; Bohl, William

    2011-06-01

    Metallic pressure tanks used in space missions are inherently vulnerable to hypervelocity impacts from micrometeoroids and orbital debris; thereby knowledge of impact damage and its effect on the tank integrity is crucial to a spacecraft risk assessment. This paper describes tests that have been performed to assess the effects of hypervelocity impact (HVI) damage on Titanium (Ti) pressure vessels burst pressure and characteristics. The series consists of a pair of HVI impact tests on water-filled Ti tanks (water as a surrogate to the propellant) and subsequent burst tests of these tanks and an undamaged control tank. The tanks were placed behind Aluminum (Al) shields and then each was impacted with a 7 km/s projectile. The resulting impact debris plumes partially penetrated the Ti tank surfaces resulting in a distribution of craters. During the burst tests, the tank that failed at a lower burst pressure did appear to have the failure initiating at a crater site with observed spall cracks. A fracture mechanics analysis that provides insight into how the cracks associated with a spall site initiate a failure cascade is discussed.

  12. Burst Pressure Failure of Titanium Tanks Damaged by Secondary Plumes from Hypervelocity Impacts on Aluminum Shields

    NASA Technical Reports Server (NTRS)

    Nahra, Henry; Ghosn, Louis; Christiansen, Eric; Davis, B. Alan; Keddy, Chris; Rodriquez, Karen; Miller, Joshua; Bohl, William

    2011-01-01

    Metallic pressure tanks used in space missions are inherently vulnerable to hypervelocity impacts from micrometeoroids and orbital debris; thereby knowledge of impact damage and its effect on the tank integrity is crucial to a spacecraft risk assessment. This paper describes tests that have been performed to assess the effects of hypervelocity impact (HVI) damage on Titanium alloy (Ti-6Al-4V) pressure vessels burst pressure and characteristics. The tests consisted of a pair of HVI impact tests on water-filled Ti-6Al-4V tanks (water being used as a surrogate to the actual propellant) and subsequent burst tests as well as a burst test on an undamaged control tank. The tanks were placed behind Aluminum (Al) shields and then each was impacted with a 7 km/s projectile. The resulting impact debris plumes partially penetrated the Ti-6Al-4V tank surfaces resulting in a distribution of craters. During the burst tests, the tank that failed at a lower burst pressure did appear to have the failure initiating at a crater site with observed spall cracks. A fracture mechanics analysis showed that the tanks failure at the impact location may have been due to a spall crack that formed upon impact of a fragmentation on the Titanium surface. This result was corroborated with a finite element analysis from calculated Von-Mises and hoop stresses.

  13. Burst pressure failure of titanium tanks damaged by secondary plumes from hypervelocity impacts on aluminum shields

    NASA Astrophysics Data System (ADS)

    Nahra, Henry; Ghosn, L.; Christiansen, E.; Davis, B. A.; Keddy, C.; Rodriguez, K.; Miller, J.; Bohl, W.

    2012-03-01

    Metallic pressure tanks used in space missions are inherently vulnerable to hypervelocity impacts from micrometeoroids and orbital debris; thereby knowledge of impact damage and its effect on the tank integrity is crucial to a spacecraft risk assessment. This paper describes tests that have been performed to assess the effects of hypervelocity impact (HVI) damage on Titanium alloy (Ti-6Al-4V) pressure vessels burst pressure and characteristics. The tests consisted of a pair of HVI impact tests on water-filled Ti-6Al-4V tanks (water being used as a surrogate to the actual propellant) and subsequent burst tests as well as a burst test on an undamaged control tank. The tanks were placed behind Aluminum (Al) shields and then each was impacted with a 7 km/s projectile. The resulting impact debris plumes partially penetrated the Ti-6Al-4V tank surfaces resulting in a distribution of craters. During the burst tests, the tank that failed at a lower burst pressure did appear to have the failure initiating at a crater site with observed spall cracks. A fracture mechanics analysis showed that the tanks failure at the impact location may have been due to a spall crack that formed upon impact of a fragmentation on the Titanium surface. This result was corroborated with a finite element analysis from calculated Von-Mises and hoop stresses.

  14. The Velocity Distribution of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Rossi, Elena M.; Kobayashi, Shiho; Sari, Re'em

    2014-11-01

    We consider the process of stellar binaries tidally disrupted by a supermassive black hole (BH). For highly eccentric orbits, as one star is ejected from the three-body system, the companion remains bound to the BH. Hypervelocity stars (HVSs) observed in the Galactic halo and S-stars observed orbiting the central BH may originate from such mechanism. In this paper, we predict the velocity distribution of the ejected stars of a given mass, after they have traveled out of the Galactic potential. We use both analytical methods and Monte Carlo simulations. We find that each part of the velocity distribution encodes different information. At low velocities <800 km s-1, the Galactic potential universally shapes the observed distribution, which rises toward a peak, related to the Galactic escape velocity. Beyond the peak, the velocity distribution depends on binary mass and separation distributions. Finally, the finite star life introduces a break related to their mass. A qualitative comparison of our models with current observations shows the great potential of HVSs to constrain bulge and Galactic properties. Standard choices for parameter distributions predict velocities below and above ~800 km s-1 with equal probability, while none are observed beyond ~700 km s-1 and the current detections are more clustered at low velocities 300-400 km s-1. These features may indicate that the separation distribution of binaries that reach the tidal sphere is not flat in logarithmic space, as observed in more local massive binaries, but has more power toward larger separations, enhancing smaller velocities. In addition, the binary formation/evolution process or the injection mechanism might also induce a cut-off a min ~ 10 R ⊙ in the separation distribution.

  15. Dynamic Optical Investigations of Hypervelocity Impact Damage

    NASA Astrophysics Data System (ADS)

    Lamberson, Leslie Elise

    One of the prominent threats in the endeavor to develop next-generation space assets is the risk of space debris impact in earth's orbit and micrometeoroid impact damage in near-earth orbit and deep space. To date, there is no study available which concentrates on the analysis of dynamic crack growth from hypervelocity impacts on such structures, resulting in their eventual catastrophic degradation. Experiments conducted using a unique two-stage light-gas gun facility have examined the in situ dynamic fracture of brittle polymers subjected to this high-energy-density event. Optical techniques of caustics and photoelasticity, combined with high-speed photography up to 100 million frames per second, analyze crack growth behavior of Mylar and Homalite 100 thin plates after impact by a 1.8 mm diameter nylon 6-6 right cylindrical slug at velocities ranging from 3 to 7 km/s (7000--15500 mph). Crack speeds in both polymers averaged between 0.2 and 0.47 cR, the Rayleigh wave speed (450--1000 mph). Shadow spots and surrounding caustics reveal time histories of the dynamic stress intensity factor, as well as the energy release rate ahead of the mode-I, or opening, crack tips. Results indicate that even under extreme impact conditions of out of-plane loading, highly localized heating, and energetic impact phenomena involving plasma formation and ejecta, the dynamic fracture process occurs during a deformation regime dominated by in-plane loading. These findings imply that the reliability of impacted, thin-walled, plate and shell space structures, idealized by the experimental configuration investigated, can be predicted by the well defined principles of classical dynamic fracture mechanics.

  16. Measurement Techniques for Hypervelocity Impact Test Fragments

    NASA Technical Reports Server (NTRS)

    Hill, Nicole E.

    2008-01-01

    The ability to classify the size and shape of individual orbital debris fragments provides a better understanding of the orbital debris environment as a whole. The characterization of breakup fragmentation debris has gradually evolved from a simplistic, spherical assumption towards that of describing debris in terms of size, material, and shape parameters. One of the goals of the NASA Orbital Debris Program Office is to develop high-accuracy techniques to measure these parameters and apply them to orbital debris observations. Measurement of the physical characteristics of debris resulting from groundbased, hypervelocity impact testing provides insight into the shapes and sizes of debris produced from potential impacts in orbit. Current techniques for measuring these ground-test fragments require determination of dimensions based upon visual judgment. This leads to reduced accuracy and provides little or no repeatability for the measurements. With the common goal of mitigating these error sources, allaying any misunderstandings, and moving forward in fragment shape determination, the NASA Orbital Debris Program Office recently began using a computerized measurement system. The goal of using these new techniques is to improve knowledge of the relation between commonly used dimensions and overall shape. The immediate objective is to scan a single fragment, measure its size and shape properties, and import the fragment into a program that renders a 3D model that adequately demonstrates how the object could appear in orbit. This information would then be used to aid optical methods in orbital debris shape determination. This paper provides a description of the measurement techniques used in this initiative and shows results of this work. The tradeoffs of the computerized methods are discussed, as well as the means of repeatability in the measurements of these fragments. This paper serves as a general description of methods for the measurement and shape analysis of

  17. Emission FTIR analyses of thin microscopic patches of jet fuel residue deposited on heated metal surface

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.; Vogel, P.

    1984-01-01

    Deposits laid down in patches on metal strips in a high pressure/high temperature fuel system simulator operated with aerated fuel at varying flow rates were analyzed by emission FTIR in terms of functional groups. Significant differences were found in the spectra and amounts of deposits derived from fuels to which small concentrations of oxygen-, nitrogen-, or sulfur-containing heterocyclics or metal naphthenates were added. The spectra of deposits generated on strips by heating fuels and air in a closed container were very different from those of the flowing fluid deposits. One such closed-container dodecane deposit on silver gave a strong surface-enhanced Raman spectrum.

  18. Structural Damage Prediction and Analysis for Hypervelocity Impact: Consulting

    NASA Technical Reports Server (NTRS)

    1995-01-01

    A portion of the contract NAS8-38856, 'Structural Damage Prediction and Analysis for Hypervelocity Impacts,' from NASA Marshall Space Flight Center (MSFC), included consulting which was to be documented in the final report. This attachment to the final report contains memos produced as part of that consulting.

  19. SPH (smoothed particle hydrodynamics) simulations of hypervelocity impacts

    SciTech Connect

    Cloutman, L.D.

    1991-01-24

    The smoothed particle hydrodynamics (SPH) method has been used to simulate several cases of hypervelocity impact in an exploratory study to determine the suitability of the method for such problems. The calculations compare favorably with experimental results and with other numerical simulations. We discuss the requirements that must be satisfied for SPH to produce accurate simulations of such problems. 18 refs., 9 figs.

  20. Hypervelocity impact tests on Space Shuttle Orbiter thermal protection material

    NASA Technical Reports Server (NTRS)

    Humes, D. H.

    1977-01-01

    Hypervelocity impact tests were conducted to simulate the damage that meteoroids will produce in the Shuttle Orbiter leading edge structural subsystem material. The nature and extent of the damage is reported and the probability of encountering meteoroids with sufficient energy to produce such damage is discussed.

  1. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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  2. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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  3. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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  4. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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  5. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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  6. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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  7. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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  8. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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  9. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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  10. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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  11. Survey of the hypervelocity impact technology and applications.

    SciTech Connect

    Chhabildas, Lalit Chandra; Orphal, Dennis L.

    2006-05-01

    HVIS 2005 was a clear success. The Symposium brought together nearly two hundred active researchers and students from thirteen countries around the world. The 84 papers presented at HVIS 2005 constitute an ''update'' on current research and the state-of-the-art of hypervelocity science. Combined with the over 7000 pages of technical papers from the eight previous Symposia, beginning in 1986, all published in the International Journal of Impact Engineering, the papers from HVIS 2005 add to the growing body of knowledge and the progressing state-of-the-art of hypervelocity science. It is encouraging to report that even with the limited funding resources compared to two decades ago, creativity and ingenuity in hypervelocity science are alive and well. There is considerable overlap in different disciplines that allows researchers to leverage. Experimentally, higher velocities are now available in the laboratory and are ideally suited for space applications that can be tied to both civilian (NASA) and DoD military applications. Computationally, there is considerable advancement both in computer and modeling technologies. Higher computing speeds and techniques such as parallel processing allow system level type applications to be addressed directly today, much in contrast to the situation only a few years ago. Needless to say, both experimentally and computationally, the ultimate utility will depend on the curiosity and the probing questions that will be incumbent upon the individual researcher. It is quite satisfying that over two dozen students attended the symposium. Hopefully this is indicative of a good pool of future researchers that will be needed both in the government and civilian industries. It is also gratifying to note that novel thrust areas exploring different and new material phenomenology relevant to hypervelocity impact, but a number of other applications as well, are being pursued. In conclusion, considerable progress is still being made that is

  12. High strain rate and high temperature behaviour of metallic materials for jet engine turbine containment

    NASA Astrophysics Data System (ADS)

    Gálvez, F.; Cendón, D.; Enfedaque, A.; Sánchez-Gálvez, V.

    2006-08-01

    This work presents a study on the mechanical characterisation of the materials involved in air jet engine turbines. The final objective is to analyse the phenomenon of a turbine blade off failure, to verify the requirements of the case containment. The materials in the turbine are under high temperatures, ranging from 400circC to 800circC and when the fail of the blade occurs if impacts against the case, reaching strain rates up to 103 s - 1. To obtain the behaviour of the materials, testing at high strain rate and high temperature at one time is necessary. The experimental set-up used was a split Hopkinson pressure bar, with a high temperature furnace adapted. The bars used on the device were high strength nickel alloys with a cooling system to decrease the temperature of the measurement devices. The effect of wave dispersion due to the temperature gradient has been also studied to correct the measurements if necessary. The material tested has been the FV535 stainless steel used on the case. The full stress-strain curves at different temperatures and at strain rates up to 103 s-1 have been obtained. The experimental results show a marked influence of the strain rate and the temperature that cannot be neglected. The Johnson-Cook material model has been used to fit the results of the material tests.

  13. Vapor Explosion of Coolant Jet When Penetrating a Hot Molten Metal

    SciTech Connect

    Perets, Y.; Harari, R.; Sher, E.

    2005-06-15

    The vapor explosion phenomenon is investigated experimentally for a geometrical arrangement in which a cold liquid (water) jet is injected into a hot liquid surface (tin). Medium-scale experiments using 1 kg of molten tin were performed in an open geometry experiment system. In the first phase of the research, the influence of the injection mass flow rate on the likelihood of vapor explosion was investigated in order to map the various relevant regimes. In the second phase, the influence of some selected parameters on the interaction was studied to characterize the relevant parameters of the vapor explosion phenomenon.The range of the initial tin and water temperatures that leads to vapor explosion has been determined in order to define the thermal interaction zone. It is noticed that vapor explosion can occur at high water temperatures even near the saturation point. The delay time for the explosion to occur and the degree of the interaction violence were correlated with the initial tin and water temperatures. We also clarified the triggering point and noted a correlation between the quench temperature and the likelihood of the vapor explosion occurrence.

  14. Hypervelocity Impact Initiation of Explosive Transfer Lines

    NASA Technical Reports Server (NTRS)

    Bjorkman, Michael D.; Christiansen, Eric L.

    2012-01-01

    The Gemini, Apollo and Space Shuttle spacecraft utilized explosive transfer lines (ETL) in a number of applications. In each case the ETL was located behind substantial structure and the risk of impact initiation by micrometeoroids and orbital debris was negligible. A current NASA program is considering an ETL to synchronize the actuation of pyrobolts to release 12 capture latches in a contingency. The space constraints require placing the ETL 50 mm below the 1 mm thick 2024-T72 Whipple shield. The proximity of the ETL to the thin shield prompted analysts at NASA to perform a scoping analysis with a finite-difference hydrocode to calculate impact parameters that would initiate the ETL. The results suggest testing is required and a 12 shot test program with surplused Shuttle ETL is scheduled for February 2012 at the NASA White Sands Test Facility. Explosive initiation models are essential to the analysis and one exists in the CTH library for HNS I, but not the HNS II used in the Shuttle 2.5 gr/ft rigid shielded mild detonating cord (SMDC). HNS II is less sensitive than HNS I so it is anticipated that these results using the HNS I model are conservative. Until the hypervelocity impact test results are available, the only check on the analysis was comparison with the Shuttle qualification test result that a 22 long bullet would not initiate the SMDC. This result was reproduced by the hydrocode simulation. Simulations of the direct impact of a 7 km/s aluminum ball, impacting at 0 degree angle of incidence, onto the SMDC resulted in a 1.5 mm diameter ball initiating the SMDC and 1.0 mm ball failing to initiate it. Where one 1.0 mm ball could not initiate the SMDC, a cluster of six 1.0 mm diameter aluminum balls striking simultaneously could. Thus the impact parameters that will result in initiating SMDC located behind a Whipple shield will depend on how well the shield fragments the projectile and spreads the fragments. An end-to-end simulation of the impact of an

  15. Hypervelocity nanoparticle impacts on free-standing graphene: A sui generis mode of sputtering

    SciTech Connect

    Eller, Michael J.; Della-Negra, Serge; Kim, Hansoo; Young, Amanda E.

    2015-01-28

    The study of the interaction of hypervelocity nano-particles with a 2D material and ultra-thin targets (single layer graphene, multi-layer graphene, and amorphous carbon foils) has been performed using mass selected gold nano-particles produced from a liquid metal ion source. During these impacts, a large number of atoms are ejected from the graphene, corresponding to a hole of ∼60 nm{sup 2}. Additionally, for the first time, secondary ions have been observed simultaneously in both the transmission and reflection direction (with respect to the path of the projectile) from a 2D target. The ejected area is much larger than that predicted by molecular dynamic simulations and a large ionization rate is observed. The mass distribution and characteristics of the emitted secondary ions are presented and offer an insight into the process to produce the large hole observed in the graphene.

  16. Quantitative analysis of toxic metals lead and cadmium in water jet by laser-induced breakdown spectroscopy.

    PubMed

    Cheri, M Sadegh; Tavassoli, S H

    2011-03-20

    Laser-induced breakdown spectroscopy (LIBS) has been applied to the analysis of toxic metals Pb and Cd in Pb(NO3)2 and Cd(NO3)2.4H2O aqueous solutions, respectively. The plasma is generated by focusing a nanosecond Nd:YAG (λ=1064 nm) laser on the surface of liquid in the homemade liquid jet configuration. With an assumption of local thermodynamic equilibrium (LTE), calibration curves of Pb and Cd were obtained at different delay times between 1 to 5 μs. The temporal behavior of limit of detections (LOD) was investigated and it is shown that the minimum LODs for Pb and Cd are 4 and 68 parts in 10(6) (ppm), respectively. In order to demonstrate the correctness of the LTE assumption, plasma parameters including plasma temperature and electron density are evaluated, and it is shown that the LTE condition is satisfied at all delay times. PMID:21460994

  17. Jet formation in spallation of metal film from substrate under action of femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Inogamov, N. A.; Zhakhovskii, V. V.; Khokhlov, V. A.

    2015-01-01

    It is well known that during ablation by an ultrashort laser pulse, the main contribution to ablation of the substance is determined not by evaporation, but by the thermomechanical spallation of the substance. For identical metals and pulse parameters, the type of spallation is determined by film thickness d f . An important gauge is metal heating depth d T at the two-temperature stage, at which electron temperature is higher than ion temperature. We compare cases with d f < d T (thin film) and d f ≫ d T (bulk target). Radius R L of the spot of heating by an optical laser is the next (after d f ) important geometrical parameter. The morphology of film bulging in cases where d f < d T on the substrate (blistering) changes upon a change in radius R L in the range from diffraction limit R L ˜ λ to high values of R L ≫ λ, where λ ˜ 1 μm is the wavelength of optical laser radiation. When d f < d T , R L ˜ λ, and F abs > F m, gold film deposited on the glass target acquires a cupola-shaped blister with a miniature frozen nanojet in the form of a tip on the circular top of the cupola ( F abs and F m are the absorbed energy and the melting threshold of the film per unit surface area of the film). A new physical mechanism leading to the formation of the nanojet is proposed.

  18. Hypervelocity Impact Experiments on Epoxy/Ultra-High Molecular Weight Polyethylene Composite Panels Reinforced with Nanotubes

    NASA Technical Reports Server (NTRS)

    Khatiwada, Suman; Laughman, Jay W.; Armada, Carlos A.; Christiansen, Eric L.; Barrera, Enrique V.

    2012-01-01

    Advanced composites with multi-functional capabilities are of great interest to the designers of aerospace structures. Polymer matrix composites (PMCs) reinforced with high strength fibers provide a lightweight and high strength alternative to metals and metal alloys conventionally used in aerospace architectures. Novel reinforcements such as nanofillers offer potential to improve the mechanical properties and add multi-functionality such as radiation resistance and sensing capabilities to the PMCs. This paper reports the hypervelocity impact (HVI) test results on ultra-high molecular weight polyethylene (UHMWPE) fiber composites reinforced with single-walled carbon nanotubes (SWCNT) and boron nitride nanotubes (BNNT). Woven UHMWPE fabrics, in addition to providing excellent impact properties and high strength, also offer radiation resistance due to inherent high hydrogen content. SWCNT have exceptional mechanical and electrical properties. BNNT (figure 1) have high neutron cross section and good mechanical properties that add multi-functionality to this system. In this project, epoxy based UHMWPE composites containing SWCNT and BNNT are assessed for their use as bumper shields and as intermediate plates in a Whipple Shield for HVI resistance. Three composite systems are prepared to compare against one another: (I) Epoxy/UHMWPE, (II) Epoxy/UHMWPE/SWCNT and (III) Epoxy/UHMWPE/SWCNT/BNNT. Each composite is a 10.0 by 10.0 by 0.11 cm3 panel, consisting of 4 layers of fabrics arranged in cross-ply orientation. Both SWCNT and BNNT are 0.5 weight % of the fabric preform. Hypervelocity impact tests are performed using a two-stage light gas gun at Rice University

  19. Jet formation in spallation of metal film from substrate under action of femtosecond laser pulse

    SciTech Connect

    Inogamov, N. A.; Zhakhovskii, V. V.; Khokhlov, V. A.

    2015-01-15

    It is well known that during ablation by an ultrashort laser pulse, the main contribution to ablation of the substance is determined not by evaporation, but by the thermomechanical spallation of the substance. For identical metals and pulse parameters, the type of spallation is determined by film thickness d{sub f}. An important gauge is metal heating depth d{sub T} at the two-temperature stage, at which electron temperature is higher than ion temperature. We compare cases with d{sub f} < d{sub T} (thin film) and d{sub f} ≫ d{sub T} (bulk target). Radius R{sub L} of the spot of heating by an optical laser is the next (after d{sub f}) important geometrical parameter. The morphology of film bulging in cases where d{sub f} < d{sub T} on the substrate (blistering) changes upon a change in radius R{sub L} in the range from diffraction limit R{sub L} ∼ λ to high values of R{sub L} ≫ λ, where λ ∼ 1 μm is the wavelength of optical laser radiation. When d{sub f} < d{sub T}, R{sub L} ∼ λ, and F{sub abs} > F{sub m}, gold film deposited on the glass target acquires a cupola-shaped blister with a miniature frozen nanojet in the form of a tip on the circular top of the cupola (F{sub abs} and F{sub m} are the absorbed energy and the melting threshold of the film per unit surface area of the film). A new physical mechanism leading to the formation of the nanojet is proposed.

  20. First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation

    SciTech Connect

    Larsson, Daniel H.; Lundstroem, Ulf; Burvall, Anna; Hertz, Hans M.

    2013-02-15

    Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with {approx}7 {mu}m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 {mu}m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.

  1. Hypervelocity impact response of aluminum multi-wall structures

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Bean, Alan J.

    1991-01-01

    The results of an investigation in which the perforation resistance of aluminum multiwall structures is analyzed under a variety of hypervelocity impact loading conditions are presented. A comparative analysis of the impact damage in structural systems with two or more bumpers and the damage in single-bumper systems of similar weight is performed to determine the advantages and disadvantages of employing more than one bumper in structural wall systems for long-duration spacecraft. A significant increase in protection against perforation by hypervelocity projectiles can be achieved if a single bumper is replaced by two bumpers of similar weight while the total wall spacing is kept constant. It is found that increasing the number of bumpers beyond two while keeping the total stand-off distance constant does not result in a substantial increase in protection over that offered by two bumpers of similar weight.

  2. Optimum Structure of Whipple Shield against Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Lee, Minhyung

    2013-06-01

    It has been known that the spacecraft protection issues against space debris or meteoroid impact damage are of great importance. Whipple shield structures (double spaced plates) have been investigated and empirical ballistic limit curve (BLCs) are developed. In this paper, we like to investigate an optimum Whipple Shield structure of fixed areal density and space. To do this, a new in-house SPH code has been used. Last 20 years SPH (Smoothed Particle Hydrodynamics) numerical scheme has been widely applied to the hypervelocity impact problems because of the limited velocity range and cost of test. We first examined the extent of debris spreading which seems to be a key factor to the back plate impact. The debris cloud expansion angle shows a maximum value. Then, a series of hypervelocity impact simulations were conducted to predict the critical impacting sphere diameter. It has been found that there is an optimum thickness ratio of front bumper to real wall.

  3. Spacecraft outer thermal blankets as hypervelocity impact bumpers

    NASA Astrophysics Data System (ADS)

    Cour-Palais, B. G.

    1996-05-01

    A thermal barrier consisting of a woven fabric outer layer followed by several layers of aluminized mylar insulation has been the primary impact protection against micrometeoroid and orbital impacts for many spacecraft currently in orbit. This paper examines its effectiveness as a hypervelocity "bumper" based on the performance of a NASA space suit. In this case, the thermal barrier consisted of a fabric layer followed by five layers of the aluminized mylar, which shielded either an aluminum rear wall or a rubberized pressure garment. The total areal density of the fabric and mylar layers was 0.052 g/cm2 and the fabric stand-off was 4 mm from the protected surfaces, with the aluminized mylar filling the space. Test results obtained with hypervelocity aluminum projectile impacts up to 8.5 km/s on the thermal barrier and aluminum wall are described, and a semi-empirical equation for this type of shielding is suggested.

  4. A new technique for ground simulation of hypervelocity debris

    NASA Technical Reports Server (NTRS)

    Roybal, R.; Shively, J.; Stein, C.; Miglionico, C.; Robertson, R.

    1995-01-01

    A series of hypervelocity damage experiments were preformed on spacecraft materials. These experiments employed a technique which accelerates micro flyer plates simulating space debris traveling at 3 to 8 km/sec. The apparatus used to propel the micro flyer plates was compact and fit well into a space environmental chamber equipped with instrumentation capable of analyzing the vapor ejected from the sample. Mechanical damage to the sample was also characterized using optical and scanning electron microscpopy. Data for this work was obtained from hypervelocity impacts on a polysulfone resin and a graphite polysulfone composite. Polysulfone was selected because it was flown on the Long Duration Exposure Facility (LDEF) which spent several years in low earth orbit (LEO). Chemistry of the vapor produced by the impact was analyzed with a time of flight mass spectrometer, (TOFMS). This represents the first time that ejected vapors from hypervelocity collisions were trapped and analyzed with a mass spectrometer. With this approach we are able to study changes in the vapor chemistry as a function of time after impact, obtain a velocity measurement of the vapor, and estimate a temperature of the surface at time of impact using dynamic gas equations. Samples of the vapor plume may be captured and examined by transmission electron microscopy. Studies were also conducted to determine mechanical damage to a graphite polysulfone composite and a polysulfone resin. Impact craters were examined under optical and scanning electron microscopes. The collision craters in the matrix were typical of those shown in conventional shock experiments. However, the hypervelocity collisions with the graphite polysulfone composite were remarkably different than those with the resin.

  5. Hypervelocity supersonic nozzle beam source of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Freedman, A.; Unkel, W.; Silver, J.; Kolb, C.

    1984-01-01

    A hypervelocity source of atomic oxygen was developed. Dissociation of molecular oxygen is accomplished by injection into a flow of helium and/or argon which has been heated in a commercial plasma torch. Atomic velocities of up to 4 kms(-1) were produced; recent improvements offer the possibility of even higher velocities. This source was utilized in studies of translational-to-vibrational energy transfer in carbon dioxide and in an investigation of the shuttle glow effect.

  6. Damage Analysis for Hypervelocity Impact Experiments on Spaceship Windows Glass

    NASA Astrophysics Data System (ADS)

    Jiyun, Y.; Jidong, Z.; Zizheng, G.; Hewei, P.

    2010-06-01

    The hypervelocity impact characteristics in fused silica glass, which is used for the outermost pane of the windshield as the critical part of the thermal protection system of spacecraft, were studied by 37 impact experiments with different millimeter diameter projectiles up to the velocity of 7 km/s launched by two stage light-gas-gun facility. The empirical damage equations were obtained from experiment data by the least square method and they were compared with NASA damage equations.

  7. Skin-friction gauge for use in hypervelocity impulse facilities

    NASA Technical Reports Server (NTRS)

    Kelly, G. M.; Simmons, J. M.; Paull, A.

    1992-01-01

    A transducer is presented which can measure as rise-time of about 20 microsec, and is thereby applicable to measurements in the high-enthalpy flows associated with hypervelocity impulse facilities. Results are presented which demonstrate the effectiveness of the concept in the case of skin-friction measurements conducted on a flat plate at Mach 3.2. The calibration used was against theoretical skin-friction values in a simple flow.

  8. Hypervelocity impact simulation for micrometeorite and debris shield design

    NASA Technical Reports Server (NTRS)

    Fahrenthold, Eric P.

    1992-01-01

    A new capability has been developed for direct computer simulation of hypervelocity impacts on multi-plate orbital debris shields, for combinations of low shield thickness and wide shield spacing which place extreme demands on conventional Eulerian analysis techniques. The modeling methodology represents a novel approach to debris cloud dynamics simulation, a problem of long term interest in the design of space structures. Software implementation of the modeling methodology provides a new design tool for engineering analysis of proposed orbital debris protection systems.

  9. Experimental hypervelocity impact effects on simulated planetesimal materials

    SciTech Connect

    Tedeschi, W.J.; Schulze, J.F.; Remo, J.L.; Young, R.P. Jr

    1994-08-01

    Experimental results are presented from a series of hypervelocity impact tests on simulated comet and asteroid materials for the purpose of characterizing their response to hypervelocity kinetic energy impacts. Nine tests were conducted at the Air Force Arnold Engineering Development Center (AEDC) S1 Range Facility on ice, rock, and iron target samples using a spherical 2.39 mm diameter aluminum impactor (0.0192 gm) at impact velocities of from 7.6 to 8.4 km/sec. The test objectives were to collect target response phenomenology data on cratering, momentum deposition and enhancement, target fragmentation, and material response under hypervelocity impact loading conditions. A carefully designed ballistic pendulum was used to measure momentum deposition into the targets. Observations and measurements of the impacted samples provide important insights into the response of these materials to kinetic energy impacts, especially in regards to unexpectedly large measured values of momentum enhancement to some of the targets. Such information is required to allow us to successfully deflect or fragment comets or asteroids which might someday be detected on collision trajectories with Earth.

  10. Theoretical and numerical predictions of hypervelocity impact-generated plasma

    SciTech Connect

    Li, Jianqiao; Song, Weidong Ning, Jianguo

    2014-08-15

    The hypervelocity impact generated plasmas (HVIGP) in thermodynamic non-equilibrium state were theoretically analyzed, and a physical model was presented to explore the relationship between plasma ionization degree and internal energy of the system by a group of equations including a chemical reaction equilibrium equation, a chemical reaction rate equation, and an energy conservation equation. A series of AUTODYN 3D (a widely used software in dynamic numerical simulations and developed by Century Dynamic Inc.) numerical simulations of the impacts of hypervelocity Al projectile on its targets at different incident angles were performed. The internal energy and the material density obtained from the numerical simulations were then used to calculate the ionization degree and the electron temperature. Based on a self-developed 2D smooth particle hydrodynamic (SPH) code and the theoretical model, the plasmas generated by 6 hypervelocity impacts were directly simulated and their total charges were calculated. The numerical results are in good agreements with the experimental results as well as the empirical formulas, demonstrating that the theoretical model is justified by the AUTODYN 3D and self-developed 2D SPH simulations and applicable to predict HVIGPs. The study is of significance for astrophysical and cosmonautic researches and safety.

  11. Hyper-velocity impact risk assessment study for LOFT

    NASA Astrophysics Data System (ADS)

    Perinati, Emanuele

    Within the ESA Cosmic Vision programme, the Large Observatory For x-ray Timing (LOFT) mission is one of the candidates for the M3 slot opportunity. LOFT is an x-ray (2-30 keV) experiment with two instruments on-board: the Large Area Detector (LAD) and the Wide Field Monitor (WFM). Both are based on Silicon Drift Detectors (SDDs). Due to the design of the instrumental configuration, hyper-velocity impacts of micrometeoroids and orbital debris represent a significant hazard factor. During the three-year assessment phase of LOFT, we performed experimental test campaigns at the MPIK Van de Graaff accelerator to measure the degradation of LOFT SDD prototypes induced by hyper-velocity impacts. For the WFM, to mitigate the impact risk we designed and tested at the TUM plasma accelerator a compact double-wall shield using thin (~10 micron) foils of Kapton and Polypropylene, capable to effectively stop hyper-velocity particles up to 70 micron in size, in a remarkable agreement with simulations performed in ESABASE2. We present the results of these activities in the context of LOFT, and brievly discuss the potential applicability of the SDD as a debris detector.

  12. Impact features tracing hypervelocity airbursts on earth from the atmosphere to the ground

    NASA Astrophysics Data System (ADS)

    Courty, M. M.

    2012-12-01

    In the absence of deep craters, impact features have been debated to possibly tracing proximal ejecta from yet undetected structure or airburst debris from a meteorite collision with the terrestrial atmosphere or lithosphere. We examine the possibility for impact features to have originated from the shock layer formed ahead of a hypervelocity collider in the earth atmosphere. This hypothesis is approached by comparing impact features from controlled materials to puzzling geological ones: (1) debris collected at the ground from a high altitude meteor airburst recorded on 2011 August 2nd in Southern France; (2) laboratory experiments performed for defense purposes at the CEA Gramat Center (France) with the Persephone hypervelocity light gas gun; (3) the Zhamanshin impact breccia, the Lybian glass, the Egyptian Dakhleh glass, the Tasmanian Darwin glass, the Australasian tektite strewnfield and the Australian Henbury crater field. The Persephone experiments include collisions from 4.1 to 7.9 km/s by a steel projectile embedded into a polycarbonate holder with a polystyrene separator on to a 40 mm thick aluminum target. The impact features been characterized by coupling Environmental SEM with EDS, Raman micro-spectrometry, XRD, TEM, Tof-SIMS, ICP-MS and isotope analyses. Similar carbonaceous polymorphs that are closely imbricated at meso to nano-scales to the crystallized components (including the metal blebs) and to the glass phases (spherules or matrix) are present in all the impact features studied. They dominantly consist of aliphatic polymers, rare aromatic compounds, with graphite-lonsdaleite inclusions. The Persephone experiments help relating the graphite-lonsdaleite couple to transformed organic residues by the transient high pressure shock (a few tens MPa) and the transient heating (ca 100°C) and the aliphatic polymers to new hydrocarbons that formed from the pulverized polycarbonate and polystyrene. The Persephone experiments provide the controlled situation

  13. Impact of effective volume ratio of a dispersant to silver nano-particles on silicon solar cell efficiency in direct ink-jet metallization

    NASA Astrophysics Data System (ADS)

    Shin, Dong-Youn; Cha, Yong-Kee; Ryu, Han-Hee; Kim, Sang-Ho

    2012-11-01

    In this study, the direct ink-jet metallization of finger electrodes on a multi-crystalline silicon solar cell is attempted and the impact of the silver particle size on solar cell efficiency is investigated using silver nano-inks with two different silver particle sizes. When the silver particle size approaches the nano-metric regime of around 18.1 nm, the solar cell efficiency is as low as 8.6%. On the other hand, the solar cell efficiency increases up to a maximum of 12.1% using silver particles that are around 180 nm in size. It is found that the dependence of the solar cell efficiency on the silver particle size is related to the effective volume ratio of a dispersant to silver. As the effective volume ratio increases, detrimental effects, such as an explosive decomposition of the dispersant and high residual stress due to the high volumetric shrinkage of a direct ink-jet printed finger electrode, result in poor contact formation which eventually leads to poor solar cell efficiency. With these experimental results, potential development directions for an ink-jet printer for the direct metallization of a silicon solar cell are comprehensively discussed.

  14. Deposition in the inner and outer corners of the JET divertor with carbon wall and metallic ITER-like wall

    NASA Astrophysics Data System (ADS)

    Beal, J.; Widdowson, A.; Heinola, K.; Baron-Wiechec, A.; Gibson, K. J.; Coad, J. P.; Alves, E.; Lipschultz, B.; Kirschner, A.; Esser, H. G.; Matthews, G. F.; Brezinsek, S.; Contributors, JET

    2016-02-01

    Rotating collectors and quartz microbalances (QMBs) are used in JET to provide time-dependent measurements of erosion and deposition. Rotation of collector discs behind apertures allows recording of the long term evolution of deposition. QMBs measure mass change via the frequency deviations of vibrating quartz crystals. These diagnostics are used to investigate erosion/deposition during JET-C carbon operation and JET-ILW (ITER-like wall) beryllium/tungsten operation. A simple geometrical model utilising experimental data is used to model the time-dependent collector deposition profiles, demonstrating good qualitative agreement with experimental results. Overall, the JET-ILW collector deposition is reduced by an order of magnitude relative to JET-C, with beryllium replacing carbon as the dominant deposit. However, contrary to JET-C, in JET-ILW there is more deposition on the outer collector than the inner. This reversal of deposition asymmetry is investigated using an analysis of QMB data and is attributed to the different chemical properties of carbon and beryllium.

  15. Twin Jet

    NASA Technical Reports Server (NTRS)

    Henderson, Brenda; Bozak, Rick

    2010-01-01

    Many subsonic and supersonic vehicles in the current fleet have multiple engines mounted near one another. Some future vehicle concepts may use innovative propulsion systems such as distributed propulsion which will result in multiple jets mounted in close proximity. Engine configurations with multiple jets have the ability to exploit jet-by-jet shielding which may significantly reduce noise. Jet-by-jet shielding is the ability of one jet to shield noise that is emitted by another jet. The sensitivity of jet-by-jet shielding to jet spacing and simulated flight stream Mach number are not well understood. The current experiment investigates the impact of jet spacing, jet operating condition, and flight stream Mach number on the noise radiated from subsonic and supersonic twin jets.

  16. Elemental analyses of hypervelocity micro-particle impact sites on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. R.; Wortman, Jim J.

    1992-01-01

    The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity micro-particles that struck the active sensors with enough energy to breakdown the 0.4 to 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. These discharge features, which include 50 micron diameter areas where the aluminum top layer has been vaporized, facilitate the location of the impacts. The high purity Al-SiO2-Si substrates allow detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) is used to create two-dimensional elemental ion intensity maps of micro-particle impact sites on the IDE sensors. The element intensities in the central craters of the impacts are corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results are used to classify the particles' origins as 'manmade', 'natural' or 'indeterminate'. The last classification results from the presence of too little impactor residue (a frequent occurrence on leading edge impacts), analytical interference from high background contamination, the lack of information on silicon residue, the limited usefulness of data on aluminum in the central craters, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters, of these features. A

  17. Hypervelocity Launcher for Aerothermodynamic Experiments. Phase 2

    NASA Technical Reports Server (NTRS)

    Scholz, Timothy J.; Bauer, David P.

    1995-01-01

    The capability of an Ultra Distributed Energy Store System (UDESS) powered electromagnetic launcher (EM) is experimentally assessed. The UDESS system was developed specifically to address the velocity speed limit seen in plasma armature EM launchers. Metal armature launch packages were also developed and tested to assess the usefulness of the UDESS concept for low velocity applications.

  18. A hypervelocity projectile launcher for well perforation

    SciTech Connect

    Albright, J.N.; Fugelso, L.E.; Lagner, G.C.; Burns, K.L.

    1989-01-01

    Current oil well perforation techniques use low- to medium-velocity gun launchers for completing wells in soft rock. Shaped-charge jets are normally used in harder, more competent rock. A device to create a much higher velocity projectile was designed. This launcher will provide an alternative technique to be used when the conventional devices do not yield the maximum well performance. It is an adaptation of the axial cavity in a high explosive (HE) annulus design, with the axial cavity being filled with a low density foam material. Two configurations were tested; both had an HE annulus filled with organic foam, one had a projectile. Comparison of the two shots was made. A time sequence of Image Intensifier Camera photographs and sequential, orthogonal flash x-ray radiographs provided information on the propagation of the foam fragments, the first shock wave disturbance, the projectile motion and deformation, and the direct shock wave transmission from the main HE charge. DYNA2D calculations were made to assist in the experimental interpretation. 25 refs., 9 figs.

  19. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    NASA Technical Reports Server (NTRS)

    Ryan, S.; Ordonez, E.; Christiansen, E. L.; Lear, D. M.

    2010-01-01

    Open cell metallic foam core sandwich panel structures are of interest for application in spacecraft micrometeoroid and orbital debris shields due to their novel form and advantageous structural and thermal performance. Repeated shocking as a result of secondary impacts upon individual foam ligaments during the penetration process acts to raise the thermal state of impacting projectiles ; resulting in fragmentation, melting, and vaporization at lower velocities than with traditional shielding configurations (e.g. Whipple shield). In order to characterize the protective capability of these structures, an extensive experimental campaign was performed by the Johnson Space Center Hypervelocity Impact Technology Facility, the results of which are reported in this paper. Although not capable of competing against the protection levels achievable with leading heavy shields in use on modern high-risk vehicles (i.e. International Space Station modules), metallic foam core sandwich panels are shown to provide a substantial improvement over comparable structural panels and traditional low weight shielding alternatives such as honeycomb sandwich panels and metallic Whipple shields. A ballistic limit equation, generalized in terms of panel geometry, is derived and presented in a form suitable for application in risk assessment codes.

  20. Jet shielding of jet noise

    NASA Technical Reports Server (NTRS)

    Simonich, J. C.; Amiet, R. K.; Schlinker, R. H.

    1986-01-01

    An experimental and theoretical study was conducted to develop a validated first principle analysis for predicting the jet noise reduction achieved by shielding one jet exhaust flow with a second, closely spaced, identical jet flow. A generalized fuel jet noise analytical model was formulated in which the acoustic radiation from a source jet propagates through the velocity and temperature discontinuity of the adjacent shielding jet. Input variables to the prediction procedure include jet Mach number, spacing, temperature, diameter, and source frequency. Refraction, diffraction, and reflection effects, which control the dual jet directivity pattern, are incorporated in the theory. The analysis calculates the difference in sound pressure level between the dual jet configuration and the radiation field based on superimposing two independent jet noise directivity patterns. Jet shielding was found experimentally to reduce noise levels in the common plane of the dual jet system relative to the noise generated by two independent jets.

  1. Status Report for the Hypervelocity Free-Flight Aerodynamic Facility

    NASA Technical Reports Server (NTRS)

    Cornelison, Charles J.; Arnold, James O. (Technical Monitor)

    1997-01-01

    The Hypervelocity Free-Flight Aerodynamic Facility, located at Ames Research Center, is NASA's only aeroballistic facility. During 1997, its model imaging and time history recording systems were the focus of a major refurbishment effort. Specifically the model detection, spark gap (light source); Kerr cell (high speed shuttering); and interval timer sub-systems were inspected, repaired, modified or replaced as required. These refurbishment efforts have fully restored the HFFAF's capabilities to a much better condition, comparable to what it was 15 years ago. Details of this refurbishment effort along with a brief discussion of future upgrade plans are presented.

  2. Supernovae without host galaxies?. Hypervelocity stars in foreign galaxies

    NASA Astrophysics Data System (ADS)

    Zinn, P.-C.; Grunden, P.; Bomans, D. J.

    2011-12-01

    Context. Harvesting the SAI supernova catalog, the most complete list of supernovae (SNe) currently available, we search for SNe that apparently do not occur within a distinct host galaxy but lie a great distance (several arcmin) apart from the host galaxy given in the catalog or even show no sign of an identifiable galaxy in their direct vicinity. Aims: We attempt to distinguish between two possible explanations of this host-lessness of a fraction of reported SNe, namely (i) that a host galaxy is too faint (of too low surface brightness) to be detected within the limits of currently available surveys (presumably a low surface brightness galaxy) or (ii) the progenitor of the SN is a hypervelocity star (HVS) that exploded kiloparsecs away from its host galaxy. Methods: We use deep imaging to test the first explanation. If no galaxy is identified within our detection limit of ~27 mag arcsec-2, which is the central surface brightness of the faintest known LSB galaxy so far, we discard this explanation and propose that the SN, after several other checks, had a hypervelocity star progenitor. We focus on observations for which this is the case and give lower limits to the actual space velocities of the progenitors, making them the first hypervelocity stars known in galaxies other than our own Milky Way. Results: Analyzing a selected subsample of five host-less SNe, we find one, SN 2006bx in UGC 5434, is a possible hypervelocity progenitor category with a high probability, exhibiting a projected velocity of ~800 km s-1. SN 1969L in NGC 1058 is most likely an example of a very extended star-forming disk visible only in the far-UV, but not in the optical wavebands. Therefore, this SN is clearly due to in situ star formation. This mechanism may also apply to two other SNe that we investigated (SN 1970L and SN 1997C), but this cannot be determined with certainty. Another SN, SN 2005 nc which is associated with a gamma-ray burst (GRB 050525), is a special case that is not

  3. Hypervelocity impact damage tolerance of fused silica glass

    NASA Technical Reports Server (NTRS)

    Edelstein, K. S.

    1992-01-01

    A test program was conducted at the NASA/Johnson Space Center (JSC) concerning hypervelocity impact damage in fused silica glass. The objectives of this test program were: to expand the penetration equation data base in the velocity range between 2 and 8 km/s; to determine how much strength remains in a glass pane that has sustained known impact damage; and to develop a relationship between crater measurements and residual strength predictions that can be utilized in the Space Shuttle and Space Station programs. The results and conclusions of the residual strength testing are discussed below. Detailed discussion of the penetration equation studies will follow in future presentations.

  4. Comparative Study of Remote Fiber Laser and Water-Jet Guided Laser Cutting of Thin Metal Sheets

    NASA Astrophysics Data System (ADS)

    Hock, Klaus; Adelmann, Benedikt; Hellmann, Ralf

    This article presents a comparison between remote laser cutting with a fiber laser and water-jet guided laser cutting using a 532 nm solid state laser. Complex contours are processed in stainless steel and brass sheets (thickness ≤ 100 μm), respectively. Results for achievable quality and productivity as well as possible applications for both systems are shown and discussed. We sustained dross free cuts with almost no heat affected zone and small kerf width for the water-jet guided process, whereas small dross, notable heat affected zone and varying kerf width where observed for remote cutting. However, process times for the water-jet guided process where considerably higher than those for remote cutting.

  5. Modeling of an Implosion Driven Hypervelocity Launcher

    NASA Astrophysics Data System (ADS)

    Loiseau, Jason; Higgins, Andrew; Szirti, Daniel; Batchelor, Patrick; Zhang, Fan; Tanguay, Vincent

    2007-06-01

    Modelling work carried out on the implosion driven launcher under concurrent development is presented. The launcher consists of a thin walled metal tube surrounded by explosive which when detonated pinches the tube shut and drives a strong shock into the projectile. The commercial hydrocode LS-DYNA was used to quantitatively and qualitatively evaluate the design parameters of the launcher and their effect on implosion dynamics and performance. These parameters include fill pressure, tube diameter, explosive layer thickness, and explosives tampering. The launcher is primarily modeled using a quasi 2D Arbitrary Langrage Euler formulation. A full 3-D axisymmetric model is also employed. The model is evaluated against experimental data previously collected. Additional developmental work on a second stage launcher taking advantage of a phase velocity between the imploding tube and explosives via the use of angled flyer plates and cones is also carried out.

  6. Survival of fossils under extreme shocks induced by hypervelocity impacts

    PubMed Central

    Burchell, M. J.; McDermott, K. H.; Price, M. C.; Yolland, L. J.

    2014-01-01

    Experimental data are shown for survival of fossilized diatoms undergoing shocks in the GPa range. The results were obtained from hypervelocity impact experiments which fired fossilized diatoms frozen in ice into water targets. After the shots, the material recovered from the target water was inspected for diatom fossils. Nine shots were carried out, at speeds from 0.388 to 5.34 km s−1, corresponding to mean peak pressures of 0.2–19 GPa. In all cases, fragmented fossilized diatoms were recovered, but both the mean and the maximum fragment size decreased with increasing impact speed and hence peak pressure. Examples of intact diatoms were found after the impacts, even in some of the higher speed shots, but their frequency and size decreased significantly at the higher speeds. This is the first demonstration that fossils can survive and be transferred from projectile to target in hypervelocity impacts, implying that it is possible that, as suggested by other authors, terrestrial rocks ejected from the Earth by giant impacts from space, and which then strike the Moon, may successfully transfer terrestrial fossils to the Moon. PMID:25071234

  7. An Imaging System for Satellite Hypervelocity Impact Debris Characterization

    NASA Technical Reports Server (NTRS)

    Moraguez, Matthew; Patankar, Kunal; Fitz-Coy, Norman; Liou, J.-C.; Cowardin, Heather

    2015-01-01

    This paper discusses the design of an automated imaging system for size characterization of debris produced by the DebriSat hypervelocity impact test. The goal of the DebriSat project is to update satellite breakup models. A representative LEO satellite, DebriSat, was constructed and subjected to a hypervelocity impact test. The impact produced an estimated 85,000 debris fragments. The size distribution of these fragments is required to update the current satellite breakup models. An automated imaging system was developed for the size characterization of the debris fragments. The system uses images taken from various azimuth and elevation angles around the object to produce a 3D representation of the fragment via a space carving algorithm. The system consists of N point-and-shoot cameras attached to a rigid support structure that defines the elevation angle for each camera. The debris fragment is placed on a turntable that is incrementally rotated to desired azimuth angles. The number of images acquired can be varied based on the desired resolution. Appropriate background and lighting is used for ease of object detection. The system calibration and image acquisition process are automated to result in push-button operations. However, for quality assurance reasons, the system is semi-autonomous by design to ensure operator involvement. This paper describes the imaging system setup, calibration procedure, repeatability analysis, and the results of the debris characterization.

  8. Hyper-velocity impact experiments with electrostatic dust accelerators

    NASA Astrophysics Data System (ADS)

    Mocker, Anna; Aust, Thomas; Bugiel, Sebastian; Hillier, Jonathan; Hornung, Klaus; Li, Yan-Wei; Strack, Heiko; Ralf, Srama

    2015-06-01

    Hypervelocity impacts (HVI) of micrometer-sized particles play an important role in a variety of fields such as the investigation of matter at extreme pressures and temperatures, shock waves in solid bodies, planetology and cosmic dust. The physical phenomena occurring upon impact are fragmentation and cratering, shock waves, the production of neutral and ionized gas, and light flashes. Advanced analysis techniques promise new insights into short time-scale high-pressure states of matter, requiring the production of high speed projectiles. Electrostatic accelerators act as a source of micrometer and sub-micrometer particles as projectiles for HVI experiments. This paper describes an HVI facility, capable of accelerating particles to over 100 km/s, currently located at the Max Planck Institute for Nuclear Physics in Heidelberg, together with planned improvements. The facility is about to be relocated to the University of Stuttgart. This is an opportunity to enhance the facility to meet the requirements of future experimental campaigns, necessary to better understand the micrometeoroid hypervelocity impact process and develop new in situ dust experiments. We will present the design of the new facility and the planned enhancements, including new diagnostic apparatus.

  9. Axial focusing of energy from a hypervelocity impact on earth

    SciTech Connect

    Boslough, M.B.; Chael, E.P.; Trucano, T.G.; Crawford, D.A.

    1994-12-01

    We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth`s surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth`s interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes.

  10. Survival of fossils under extreme shocks induced by hypervelocity impacts.

    PubMed

    Burchell, M J; McDermott, K H; Price, M C; Yolland, L J

    2014-08-28

    Experimental data are shown for survival of fossilized diatoms undergoing shocks in the GPa range. The results were obtained from hypervelocity impact experiments which fired fossilized diatoms frozen in ice into water targets. After the shots, the material recovered from the target water was inspected for diatom fossils. Nine shots were carried out, at speeds from 0.388 to 5.34 km s(-1), corresponding to mean peak pressures of 0.2-19 GPa. In all cases, fragmented fossilized diatoms were recovered, but both the mean and the maximum fragment size decreased with increasing impact speed and hence peak pressure. Examples of intact diatoms were found after the impacts, even in some of the higher speed shots, but their frequency and size decreased significantly at the higher speeds. This is the first demonstration that fossils can survive and be transferred from projectile to target in hypervelocity impacts, implying that it is possible that, as suggested by other authors, terrestrial rocks ejected from the Earth by giant impacts from space, and which then strike the Moon, may successfully transfer terrestrial fossils to the Moon. PMID:25071234

  11. Hypervelocity Impact Testing of Nickel Hydrogen Battery Cells

    NASA Technical Reports Server (NTRS)

    Frate, David T.; Nahra, Henry K.

    1996-01-01

    Nickel-Hydrogen (Ni/H2) battery cells have been used on several satellites and are planned for use on the International Space Station. In January 1992, the NASA Lewis Research Center (LeRC) conducted hypervelocity impact testing on Ni/H2 cells to characterize their failure modes. The cell's outer construction was a 24 mil-thick Inconel 718 pressure vessel. A sheet of 1.27 cm thick honeycomb was placed in front of the battery cells during testing to simulate the on-orbit box enclosure. Testing was conducted at the NASA White Sands Test Facility (WSTF). The hypervelocity gun used was a 7.6 mm (0.30 caliber) two-stage light gas gun. Test were performed at speeds of 3, 6, and 7 km/sec using aluminum 2017 spherical particles of either 4.8 or 6.4 mm diameter as the projectile. The battery cells were electrically charged to about 75 percent of capacity, then back-filled with hydrogen gas to 900 psi simulating the full charge condition. High speed film at 10,000 frames/sec was taken of the impacts. Impacts in the dome area (top) and the electrode area (middle) of the battery cells were investigated. Five tests on battery cells were performed. The results revealed that in all of the test conditions investigated, the battery cells simply vented their hydrogen gas and some electrolyte, but did not burst or generate any large debris fragments.

  12. STARFIRE: Hypervelocity railgun development for high-pressure research

    SciTech Connect

    Hawke, R.S.; Susoeff, A.R.; Asay, J.R.; Balk, J.K.; Hall, C.A.; Konrad, C.H.; McDonald, J.M.; Schuler, K.W.; Wellman, G.W.; Hickman, R.J.

    1988-09-20

    STARFIRE, a program based at Sandia National Laboratories, has as its goal the development of a hypervelocity railgun for use as a high-pressure research tool. The program has included efforts to identify and solve the problems that have inhibited reliable attainment of velocities greater than the 8 to 9 km/s attainable with two-stage light-gas guns (2SLGG). Issues studied include: (1) plasma arc formation and stabilization, (2) restrike inhibition, (3) viscous drag, (4) ratio of preload to operating stresses, (5) barrel joint design, and (6) barrel precision requirements. The system uses a 2SLGG as an injector to minimize barrel ablation and armature contamination. Hydrogen is used as the injection gas and will also serve to reduce the probability of forming secondary arcs. A VISAR optical Doppler system is used to continuously and precisely measure the projectile velocity from a standing start in the 2SLGG barrel, through several joints, the HELEOS (Hypervelocity Experimental Launcher for Equation of State) railgun barrel, and post-launch. The STARFIRE program is focused on the combined use of precision diagnostics and new experimental techniques. Results of tests are presented. 24 refs., 7 figs., 1 tab.

  13. Ejecta from Hypervelocity Dust Impacts Based on Light Flash Measurements

    NASA Astrophysics Data System (ADS)

    Drake, Keith; Sternovsky, Z.; Horányi, M.; Kempf, S.; Srama, R.

    2013-10-01

    Ejecta from hypervelocity dust impacts have been shown to depend on the impinging particles’ velocity, mass, composition, etc. (J. Friichtenicht 1965, G. Eichhorn 1976). Ejecta is thought to be responsible for developing rings and dusty atmospheres of moons throughout the solar system. In order for rings to be produced, dust velocities must be greater than the moon’s escape speed. To understand the dust impact yield; impact ejecta parameters (velocities, masses, angular distributions) must be well understood. Laboratory experiments provide direct information about the ejecta production rates and impactor fluxes. Using hypervelocity (1-60km/s) iron dust at the University of Colorado dust accelerator in Boulder, Colorado we measured the time characteristics and intensities of light flashes produced on a quartz disc from primary and secondary impacts. The flashes were measured with a photomultiplier tube at varying distances and angles. By analyzing the light flashes produced by such impacts we show that this method is a viable technique for measuring these parameters. These measurements provide detailed information about the secondary mass and velocity profiles, leading to insights into the formation of dusty rings and atmospheres.

  14. Optimum structure of Whipple shield against hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Lee, M.

    2014-05-01

    Hypervelocity impact of a spherical aluminum projectile onto two spaced aluminum plates (Whipple shield) was simulated to estimate an optimum structure. The Smooth Particle Hydrodynamics (SPH) code which has a unique migration scheme from a rectangular coordinate to an axisymmetic coordinate was used. The ratio of the front plate thickness to sphere diameter varied from 0.06 to 0.48. The impact velocities considered here were 6.7 km/s. This is the procedure we explored. To guarantee the early stage simulation, the shapes of debris clouds were first compared with the previous experimental pictures, indicating a good agreement. Next, the debris cloud expansion angle was predicted and it shows a maximum value of 23 degree for thickness ratio of front bumper to sphere diameter of 0.23. A critical sphere diameter causing failure of rear wall was also examined while keeping the total thickness of two plates constant. There exists an optimum thickness ratio of front bumper to rear wall, which is identified as a function of the size combination of the impacting body, front and rear plates. The debris cloud expansion-correlated-optimum thickness ratio study provides a good insight on the hypervelocity impact onto spaced target system.

  15. Survivability of bacteria ejected from icy surfaces after hypervelocity impact.

    PubMed

    Burchell, Mark J; Galloway, James A; Bunch, Alan W; Brandão, Pedro F B

    2003-02-01

    Both the Saturnian and Jovian systems contain satellites with icy surfaces. If life exists on any of these icy bodies (in putative subsurface oceans for example) then the possibility exists for transfer of life from icy body to icy body. This is an application of the idea of Panspermia, wherein life migrates naturally through space. A possible mechanism would be that life, here taken as bacteria, could become frozen in the icy surface of one body. If a high-speed impact occurred on that surface, ejecta containing the bacteria could be thrown into space. It could then migrate around the local region of space until it arrived at a second icy body in another high-speed impact. In this paper we consider some of the necessary steps for such a process to occur, concentrating on the ejection of ice bearing bacteria in the initial impact, and on what happens when bacteria laden projectiles hit an icy surface. Laboratory experiments using high-speed impacts with a light gas gun show that obtaining icy ejecta with viable bacterial loads is straightforward. In addition to demonstrating the viability of the bacteria carried on the ejecta, we have also measured the angular and size distribution of the ejecta produced in hypervelocity impacts on ice. We have however been unsuccessful at transferring viable bacteria to icy surfaces from bacteria laden projectiles impacting at hypervelocities. PMID:12967273

  16. Hypervelocity Impact (HVI). Volume 5; WLE High Fidelity Specimen Fg(RCC)-1

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target Fg(RCC)-1 was to study hypervelocity impacts through the reinforced carbon-carbon (RCC) panels of the Wing Leading Edge. Fiberglass was used in place of RCC in the initial tests. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  17. Hypervelocity Impact (HVI). Volume 3; WLE Small-Scale Fiberglass Panel Flat Target C-1

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target C-1 was to study hypervelocity impacts on the reinforced carbon-carbon (RCC) panels of the Wing Leading Edge. Fiberglass was used in place of RCC in the initial tests. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  18. Hypervelocity Impact (HVI). Volume 7; WLE High Fidelity Specimen RCC16R

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target RCC16R was to study hypervelocity impacts through the reinforced carbon-carbon (RCC) panels of the Wing Leading Edge. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  19. Hypervelocity Impact (HVI). Volume 6; WLE High Fidelity Specimen Fg(RCC)-2

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target Fg(RCC)-2 was to study hypervelocity impacts through the reinforced carbon-carbon (RCC) panels of the Wing Leading Edge. Fiberglass was used in place of RCC in the initial tests. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  20. A Plasma Drag Hypervelocity Particle Accelerator (HYPER)

    NASA Technical Reports Server (NTRS)

    Best, Steve R.; Rose, M. Frank

    1998-01-01

    Current debris models are able to predict the growth of the space debris problem and suggest that spacecraft must employ armor or bumper shields for some orbital altitudes now and that the problem will become worse as a function of time. The practical upper limit to the velocity distribution is on the order of 40 km/s and is associated with the natural environment. The velocity distribution of the man-made component peaks at 9-10 km/s with maximum velocity in the 14-16 km/s range. Experience in space has verified that the "high probability of impact" particles are in the microgram to milligram range. These particles can have very significant effects on coatings, insulators, and thin metallic layers. The surface of thick materials becomes pitted and the local debris component is enhanced by ejecta from the impact events. In this paper, the HYPER facility is described which produces a reasonable simulation of the man-made space debris spectrum in a controlled environment. The facility capability is discussed in terms of drive geometry, energetics, velocity distribution, diagnostics, and projectile/debris loading. The facility has been used to study impact phenomena on Space Station Freedom's solar array structure, the calibration of space debris collectors, other solar array materials, potential structural materials for use in space, electrical breakdown in the space environment, and as a means of clarifying or duplicating the impact phenomena on surfaces which have been exposed in space.

  1. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon; Christiansen, Eric; Lear, Dana

    2009-01-01

    Metallic foams are a relatively new class of materials with low density and novel physical, mechanical, thermal, electrical and acoustic properties. Although incompletely characterized, they offer comparable mechanical performance to traditional spacecraft structural materials (i.e. honeycomb sandwich panels) without detrimental through-thickness channeling cells. There are two competing types of metallic foams: open cell and closed cell. Open cell foams are considered the more promising technology due to their lower weight and higher degree of homogeneity. Leading micrometeoroid and orbital debris shields (MMOD) incorporate thin plates separated by a void space (i.e. Whipple shield). Inclusion of intermediate fabric layers, or multiple bumper plates have led to significant performance enhancements, yet these shields require additional non-ballistic mass for installation (fasteners, supports, etc.) that can consume up to 35% of the total shield weight [1]. Structural panels, such as open cell foam core sandwich panels, that are also capable of providing sufficient MMOD protection, represent a significant potential for increased efficiency in hypervelocity impact shielding from a systems perspective through a reduction in required non-ballistic mass. In this paper, the results of an extensive impact test program on aluminum foam core sandwich panels are reported. The effect of pore density, and core thickness on shielding performance have been evaluated over impact velocities ranging from 2.2 - 9.3 km/s at various angles. A number of additional tests on alternate sandwich panel configurations of comparable-weight have also been performed, including aluminum honeycomb sandwich panels (see Figure 1), Nomex honeycomb core sandwich panels, and 3D aluminum honeycomb sandwich panels. A total of 70 hypervelocity impact tests are reported, from which an empirical ballistic limit equation (BLE) has been derived. The BLE is in the standard form suitable for implementation in

  2. Hypervelocity impact effects on solar cells

    NASA Technical Reports Server (NTRS)

    Rose, M. Frank

    1992-01-01

    One of the space hazards of concern is the problem of natural matter and space debris impacting spacecraft. In addition to mechanical damage, impact velocities greater than 5 km/sec can produce shock induced ionization effects with resultant surface charging and complex chemical interactions. The upper limit of the velocity distribution for these particles is on the order of 70 km/sec. The second source of particulate matter is due to the presence of man and the machinery needed to place satellites in orbit. This 'man made' component of the space debris consists of waste, rocket exhaust, and debris caused by satellite break-up. Most of the particles are small. However as the size increases, debris purposefully thrown overboard such as garbage and human waste, combined with paint chips, plastic, wire fragments, bolts, etc., become formidable hazards which completely dominate the distribution function for some orbits. These larger fragments can produce penetration and spalling of the thick metallic structures associated with spacecraft. The particles most often encountered are aluminum oxide, associated with fuel residue, and paint chips. These debris types can have a wide range of particle sizes. It has been stated that the design of spacecraft will have to take the debris evolution into account and provide additional suitable armor for key components in the near future. The purpose of this work was to subject samples from solar power arrays, one of the key components of any spacecraft, to a debris flux typical of what might be found in space, and measure the degradation of the power panels after impact.

  3. Hypervelocity Impact Testing of International Space Station Meteoroid/Orbital Debris Shielding Using an Inhibited Shaped Charge Launcher

    NASA Technical Reports Server (NTRS)

    Kerr, Justin H.; Grosch, Donald

    2001-01-01

    Engineers at the NASA Johnson Space Center have conducted hypervelocity impact (HVI) performance evaluations of spacecraft meteoroid and orbital debris (M/OD) shields at velocities in excess of 7 km/s. The inhibited shaped charge launcher (ISCL), developed by the Southwest Research Institute, launches hollow, circular, cylindrical jet tips to approximately 11 km/s. Since traditional M/OD shield ballistic limit performance is defined as the diameter of sphere required to just perforate or spall a spacecraft pressure wall, engineers must decide how to compare ISCL derived data with those of the spherical impactor data set. Knowing the mass of the ISCL impactor, an equivalent sphere diameter may be calculated. This approach is conservative since ISCL jet tips are more damaging than equal mass spheres. A total of 12 tests were recently conducted at the Southwest Research Institute (SWRI) on International Space Station M/OD shields. Results of these tests are presented and compared to existing ballistic limit equations. Modification of these equations is suggested based on the results.

  4. Physics of debris clouds from hypervelocity impacts

    NASA Technical Reports Server (NTRS)

    Zee, Ralph

    1993-01-01

    The protection scheme developed for long duration space platforms relies primarily upon placing thin metal plates or 'bumpers' around flight critical components. The effectiveness of this system is highly dependent upon its ability to break up and redistribute the momentum of any particle which might otherwise strike the outer surface of the spacecraft. Therefore it is of critical importance to design the bumpers such that maximum dispersion of momentum is achieved. This report is devoted to an in-depth study into the design and development of a laboratory instrument which would permit the in-situ monitoring of the momentum distribution as the impact event occurs. A series of four designs were developed, constructed and tested culminating with the working instrument which is currently in use. Each design was individually tested using the Space Environmental Effects Facility (SEEF) at the Marshall Space Flight Center in Huntsville, Alabama. Along with the development of the device, an experimental procedure was developed to assist in the investigation of various bumper materials and designs at the SEEF. Preliminary results were used to compute data which otherwise were not experimentally obtainable. These results were shown to be in relative agreement with previously obtained values derived through other methods. The results of this investigation indicated that momentum distribution could in fact be measured in-situ as the impact event occurred thus giving a more accurate determination of the effects of experimental parameters on the momentum spread. Data produced by the instrument indicated a Gaussian-type momentum distribution. A second apparatus was developed and it was placed before the shield in the line of travel utilized a plate to collect impact debris scattered backwards. This plate had a passage hole in the center to allow the particle to travel through it and impact the proposed shield material. Applying the law of conservation of angular momentum a

  5. Characterization of Orbital Debris via Hyper-Velocity Ground-Based Tests

    NASA Technical Reports Server (NTRS)

    Cowardin, Heather

    2016-01-01

    The purpose of the DebriSat project is to replicate a hyper-velocity fragmentation event using modern-day spacecraft materials and construction techniques to better improve the existing DoDand NASA breakup models.

  6. MEMIN Project: The Search for Suitable Projectile Material in Meso-Scale Hypervelocity Cratering Experiments

    NASA Astrophysics Data System (ADS)

    Domke, I.; Deutsch, A.; Hecht, L.; Kenkmann, T.

    2010-03-01

    We report textural and geochemical data (EMP, LA-ICP-MS) for different types of steel and the iron meteorites Arispe (IC) and Campo del Cielo (IAB) that are evaluated as projectile materials in hypervelocity cratering experiments .

  7. MEMIN: Chemical Modification of Projectile Spheres, Target Melts and Shocked Quartz in Hypervelocity Impact Experiments

    NASA Astrophysics Data System (ADS)

    Ebert, M.; Hecht, L.; Deutsch, A.; Kenkmann, T.

    2011-03-01

    We present results of hypervelocity cratering experiments using iron meteorite as projectile and a sandstone target. The ejecta show shock features (melting, PDFs, lechatelierite) and physical as well as chemical mixing between projectile and target.

  8. Real-Time Observation of Early Stage Damage During Hypervelocity Impacts into Basalt Targets

    NASA Astrophysics Data System (ADS)

    Kimberley, J.; Ramesh, K. T.

    2012-03-01

    Hypervelocity impacts were conducted on basalt targets bonded to glass allowing for the early stages of damage accumulation to be observed in real time. Results show that significant damage accumulates before the arrival of tensile wave reflections.

  9. Ink jet printing of silver metallization for photovoltaics. Quarterly technical report, October 1, 1984-December 30, 1984

    SciTech Connect

    Vest, R.W.

    1985-01-25

    During this quarter, significant progess was made in the continuing development of the ink jet printing system for thick film circuits. The unit being used in this research is a prototype ink jet printer developed on a contract with the Naval Avionics Center. One of the first tasks completed early in the quarter was the complete documentation of this ink jet printing system as it existed. It was determined that this was an essential step in deciding what modifications were needed to the system and how these modifications would be implemented. After this initial step was completed, design modification studies were started for electronic, mechanical, and programming aspects of the system. These studies were completed at the end of the second month. The areas needing improvement were discussed and applicable changes decided upon. Some of these improvements were completed during this quarter and others have only been started. It should be noted that, although the general areas needing improvement have been identified and some changes decided upon, the exact details of how other changes will be implemented have not yet been decided. During the next months, these details will be discussed further and the modifications put in place accordingly.

  10. Elemental analyses of hypervelocity microparticle impact sites on Interplanetary Dust Experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. A.; Wortman, Jim J.; Brownlee, D. E.

    1993-01-01

    The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity microparticles (approximately 0.2 to approximately 100 micron diameter) that struck the active sensors with enough energy to break down the 0.4 or 1.0 micron thick SIO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. The high purity Al-SiO2-Si substrates allowed detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) was used to create two-dimensional elemental ion intensity maps of microparticle impact sites on the IDE sensors. The element intensities in the central craters of the impacts were corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results were used to classify the particles' origins as 'manmade,' 'natural,' or 'indeterminate.' The last classification resulted from the presence of too little impactor residue, analytical interference from high background contamination, the lack of information on silicon and aluminum residues, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters of these features. Thus far a total of 79 randomly selected microparticle impact sites from the six primary sides of the LDEF have been analyzed: 36 from tray C-9 (Leading (ram), or East, side), 18 from tray C-3

  11. Elemental Analyses of Hypervelocity Microparticle Impact Sites on Interplanetary Dust Experiment Sensor Surfaces

    NASA Technical Reports Server (NTRS)

    Simon, C. G.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. A.; Wortman, J. J.; Brownlee, D. E.

    1992-01-01

    The Interplanetary Dust Experiment (IDE) had over 450 electrically active ultra-high purity metal-oxide-silicon impact detectors located on the six primary sides of the Long Duration Exposure Facility (LDEF). Hypervelocity microparticles (approximately 0.2 to approximately 100 micron diameter) that struck the active sensors with enough energy to breakdown the 0.4 or 1.0 micron thick SiO2 insulator layer separating the silicon base (the negative electrode), and the 1000 A thick surface layer of aluminum (the positive electrode) caused electrical discharges that were recorded for the first year of orbit. The high purity Al-SiO2-Si substrates allowed detection of trace (ppm) amounts of hypervelocity impactor residues. After sputtering through a layer of surface contamination, secondary ion mass spectrometry (SIMS) was used to create two-dimensional elemental ion intensity maps of microparticle sites on the IDE sensors. The element intensities in the central craters of the impacts were corrected for relative ion yields and instrumental conditions and then normalized to silicon. The results classification resulted from the particles' origins as 'manmade', 'natural', or 'indeterminate'. The last classification resulted from the presence of too little impactor residue, analytical interference from high background contamination, the lack of information on silicon and aluminum residues, or a combination of these circumstances. Several analytical 'blank' discharges were induced on flight sensors by pressing down on the sensor surface with a pure silicon shard. Analyses of these blank discharges showed that the discharge energy blasts away the layer of surface contamination. Only Si and Al were detected inside the discharge zones, including the central craters, of these features. Thus far, a total of 79 randomly selected microparticle impact sites from the six primary sides of the LDEF were analyzed: 36 from tray C-9 (Leading (ram), or east, side), 18 from tray C-3 (Trailing

  12. Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

    SciTech Connect

    Lomov, I; Liu, B; Georgevich, V; Antoun, T

    2007-07-31

    We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

  13. Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Liu, Benjamin; Georgevich, Vlad; Antoun, Tarabay

    2007-12-01

    We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

  14. Numerical simulation of interaction of hypervelocity particle stream with a target

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya; Liu, Benjamin; Georgevich, Vlad; Antoun, Tarabay

    2007-06-01

    We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

  15. Structural Damage Prediction and Analysis for Hypervelocity Impacts: Handbook

    NASA Technical Reports Server (NTRS)

    Elfer, N. C.

    1996-01-01

    This handbook reviews the analysis of structural damage on spacecraft due to hypervelocity impacts by meteoroid and space debris. These impacts can potentially cause structural damage to a Space Station module wall. This damage ranges from craters, bulges, minor penetrations, and spall to critical damage associated with a large hole, or even rupture. The analysis of damage depends on a variety of assumptions and the area of most concern is at a velocity beyond well controlled laboratory capability. In the analysis of critical damage, one of the key questions is how much momentum can actually be transfered to the pressure vessel wall. When penetration occurs without maximum bulging at high velocity and obliquities (if less momentum is deposited in the rear wall), then large tears and rupture may be avoided. In analysis of rupture effects of cylindrical geometry, biaxial loading, bending of the crack, a central hole strain rate and R-curve effects are discussed.

  16. Design of orbital debris shields for oblique hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Fahrenthold, Eric P.

    1994-02-01

    A new impact debris propagation code was written to link CTH simulations of space debris shield perforation to the Lagrangian finite element code DYNA3D, for space structure wall impact simulations. This software (DC3D) simulates debris cloud evolution using a nonlinear elastic-plastic deformable particle dynamics model, and renders computationally tractable the supercomputer simulation of oblique impacts on Whipple shield protected structures. Comparison of three dimensional, oblique impact simulations with experimental data shows good agreement over a range of velocities of interest in the design of orbital debris shielding. Source code developed during this research is provided on the enclosed floppy disk. An abstract based on the work described was submitted to the 1994 Hypervelocity Impact Symposium.

  17. Effects of oblique impact on hypervelocity shield performance

    SciTech Connect

    Brewer, E.D.; Hendrich, W.R.; Thomas, D.G.; Smith, J.E.

    1990-01-01

    As part of the Advanced Shield Phenomenology Program, conducted from 1987 to 1989, a study of the effects of oblique impact on hypervelocity shield damage was performed. The specific threat used was an aluminum cylinder with a mass of 1.75 grams and a length to diameter ratio of one. Incidence angles of 30{degree}, 60{degree}, and 90{degree} were studied. The same layered shield assembly was tested at the different incidence angles. Testing was performed at the Arnold Engineering Development Center, Arnold Air Force Base, Tullahoma, Tennessee. Hydrocode analysis of the interaction of the projectile with the front plate was performed for each of the different incidence angles. 10 refs., 23 figs., 3 tabs.

  18. Thermodynamics analysis of aluminum plasma transition induced by hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Liu, Zhixiang; Zhang, Qingming; Ju, Yuanyuan

    2016-02-01

    The production of plasmas during hypervelocity meteoroid and space debris impact has been proposed to explain the presence of paleomagnetic fields on the lunar surface, and also the electromagnetic damage to spacecraft electronic devices. Based on Gibbs' ensemble theory, we deduce Saha equation of state and figure out the ionization degree; further, by using the derivation of Clausius-Clapeyron equation, we obtain the entropy increase and latent heat of plasma transition after vaporization; finally, we analyze the conversion efficiency of kinetic energy into internal energy, present two key contradictions, and revise them with the entropy increase, latent heat, and conversion efficiency. We analyze the aluminum plasma transition from multiple perspectives of the equation of state, latent heat of phase transition, and conversion efficiency and propose the internal energy and impact velocity criterion, based on the laws of thermodynamics.

  19. Plasmadynamic hypervelocity dust injector for the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Ticoş, Cǎtǎlin M.; Wang, Zhehui; Dorf, Leonid A.; Wurden, Glen A.

    2006-10-01

    The design and construction of a plasmadynamic device to accelerate dust to hypervelocities is presented. High speed dust will be used to measure magnetic field lines in the National Spherical Torus Experiment. The plasma gun produces a high density (ne≈1018cm-3) and low temperature (a few eV) deuterium plasma, ejected by J ×B forces which provide drag on the dust particles in its path. The dust will be entrained by the plasma to velocities of 1-30km/s, depending on the dust mass. Carbon dust particles will be used, with diameters from 1to50μm. The key components of the plasmadynamic accelerator are a coaxial plasma gun operated at 10kV (with an estimated discharge current of 200kA), a dust dispenser activated by a piezoelectric transducer, and power and remote-control systems.

  20. Study of hypervelocity meteoroid impact on orbital space stations

    NASA Technical Reports Server (NTRS)

    Leimbach, K. R.; Prozan, R. J.

    1973-01-01

    Structural damage resulting in hypervelocity impact of a meteorite on a spacecraft is discussed. Of particular interest is the backside spallation caused by such a collision. To treat this phenomenon two numerical schemes were developed in the course of this study to compute the elastic-plastic flow fracture of a solid. The numerical schemes are a five-point finite difference scheme and a four-node finite element scheme. The four-node finite element scheme proved to be less sensitive to the type of boundary conditions and loadings. Although further development work is needed to improve the program versatility (generalization of the network topology, secondary storage for large systems, improving of the coding to reduce the run time, etc.), the basic framework is provided for a utilitarian computer program which may be used in a wide variety of situations. Analytic results showing the program output are given for several test cases.

  1. Time-resolved temperature measurements in hypervelocity dust impact

    NASA Astrophysics Data System (ADS)

    Collette, A.; Drake, K.; Mocker, A.; Sternovsky, Z.; Munsat, T.; Horanyi, M.

    2013-12-01

    We present time-resolved temperature measurements of the debris cloud generated by hypervelocity dust impact. Micron- and submicron-sized iron grains were accelerated to speeds of 1-32 km/s using the 3 MV electrostatic dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies, and impacted on a tungsten target. The resulting light flashes were analyzed by an array of photomultiplier tubes equipped with narrowband interference filters to determine the blackbody temperature and radiant power of the impact-generated cloud as a function of time. We find time-averaged temperatures in the range of 2500-5000 K, increasing with velocity over the range studied; initial temperatures up to approximately twice the time averaged temperature persisting on short timescales (<1μs) compared to the 20μs duration of the flash; and that the temperature falls in a manner consistent with radiative cooling.

  2. Theoretical model for plasma expansion generated by hypervelocity impact

    SciTech Connect

    Ju, Yuanyuan; Zhang, Qingming Zhang, Dongjiang; Long, Renrong; Chen, Li; Huang, Fenglei; Gong, Zizheng

    2014-09-15

    The hypervelocity impact experiments of spherical LY12 aluminum projectile diameter of 6.4 mm on LY12 aluminum target thickness of 23 mm have been conducted using a two-stage light gas gun. The impact velocity of the projectile is 5.2, 5.7, and 6.3 km/s, respectively. The experimental results show that the plasma phase transition appears under the current experiment conditions, and the plasma expansion consists of accumulation, equilibrium, and attenuation. The plasma characteristic parameters decrease as the plasma expands outward and are proportional with the third power of the impact velocity, i.e., (T{sub e}, n{sub e}) ∝ v{sub p}{sup 3}. Based on the experimental results, a theoretical model on the plasma expansion is developed and the theoretical results are consistent with the experimental data.

  3. Design of orbital debris shields for oblique hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Fahrenthold, Eric P.

    1994-01-01

    A new impact debris propagation code was written to link CTH simulations of space debris shield perforation to the Lagrangian finite element code DYNA3D, for space structure wall impact simulations. This software (DC3D) simulates debris cloud evolution using a nonlinear elastic-plastic deformable particle dynamics model, and renders computationally tractable the supercomputer simulation of oblique impacts on Whipple shield protected structures. Comparison of three dimensional, oblique impact simulations with experimental data shows good agreement over a range of velocities of interest in the design of orbital debris shielding. Source code developed during this research is provided on the enclosed floppy disk. An abstract based on the work described was submitted to the 1994 Hypervelocity Impact Symposium.

  4. Multi-Dimensional Hydrocode Analyses of Penetrating Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Bessette, G. C.; Lawrence, R. J.; Chhabildas, L. C.; Reinhart, W. D.; Thornhill, T. F.; Saul, W. V.

    2004-07-01

    The Eulerian hydrocode, CTH, has been used to study the interaction of hypervelocity flyer plates with thin targets at velocities from 6 to 11 km/s. These penetrating impacts produce debris clouds that are subsequently allowed to stagnate against downstream witness plates. Velocity histories from this latter plate are used to infer the evolution and propagation of the debris cloud. This analysis, which is a companion to a parallel experimental effort, examined both numerical and physics-based issues. We conclude that numerical resolution and convergence are important in ways we had not anticipated. The calculated release from the extreme states generated by the initial impact shows discrepancies with related experimental observations, and indicates that even for well-known materials (e.g., aluminum), high-temperature failure criteria are not well understood, and that non-equilibrium or rate-dependent equations of state may be influencing the results.

  5. Multi-dimensional hydrocode analyses of penetrating hypervelocity impacts.

    SciTech Connect

    Saul, W. Venner; Reinhart, William Dodd; Thornhill, Tom Finley, III; Lawrence, Raymond Jeffery Jr.; Chhabildas, Lalit Chandra; Bessette, Gregory Carl

    2003-08-01

    The Eulerian hydrocode, CTH, has been used to study the interaction of hypervelocity flyer plates with thin targets at velocities from 6 to 11 km/s. These penetrating impacts produce debris clouds that are subsequently allowed to stagnate against downstream witness plates. Velocity histories from this latter plate are used to infer the evolution and propagation of the debris cloud. This analysis, which is a companion to a parallel experimental effort, examined both numerical and physics-based issues. We conclude that numerical resolution and convergence are important in ways we had not anticipated. The calculated release from the extreme states generated by the initial impact shows discrepancies with related experimental observations, and indicates that even for well-known materials (e.g., aluminum), high-temperature failure criteria are not well understood, and that non-equilibrium or rate-dependent equations of state may be influencing the results.

  6. X-ray grating interferometry for 9.25 keV design energy at a liquid-metal-jet source

    NASA Astrophysics Data System (ADS)

    Balles, A.; Fella, Ch.; Dittmann, J.; Wiest, W.; Zabler, S.; Hanke, R.

    2016-01-01

    In this paper we present a grating interferometer setup with a liquid-metal-jet source and a high resolution detector. It will be shown that this source is suitable for interferometer setups as it delivers a sufficient spatial coherence that makes a source grating unnecessary. This is confirmed twice by the results of an interferometer setup and a single grating setup, respectively. Both show comparable information on the samples. Furthermore, it was possible to measure the Talbot effect due to the self-built high resolution detector with an effective pixel size of 0.67 µm and due to the coherence of the source, thanks to a small spot size of a few microns. The information on the absorption of a nylon fiber is observed to include inline phase contrast effects. The dark-field signal of a carbon fiber reinforced polymer (CFRP) is not quite well understood because of its inhomogeneity.

  7. Secondary ion mass spectrometry (SIMS) analysis of hypervelocity microparticle impact sites on LDEF surfaces

    NASA Technical Reports Server (NTRS)

    Simon, C. G.; Buonaquisti, A. J.; Batchelor, D. A.; Hunter, J. L.; Griffis, D. P.; Misra, V.; Ricks, D. R.; Wortman, J. J.; Brownlee, D. E.; Best, S. R.

    1995-01-01

    Two dimensional elemental ion maps have been recorded for hundreds of microparticle impact sites and contamination features on LDEF surfaces. Since the majority of the analyzed surfaces were metal-oxide-silicon (MOS) impact detectors from the Interplanetary Dust Experiment, a series of 'standard' and 'blank' analyses of these surfaces are included. Hypervelocity impacts of forsterite olivine microparticles on activated flight sensors served as standards while stylus and pulsed laser simulated 'impacts' served as analytical blanks. Results showed that despite serious contamination issues, impactor residues can be identified in greater than 1/3 of the impact sites. While aluminum oxide particles could not be detected on aluminum surfaces, they were detected on germanium surfaces from row 12. Remnants of manmade debris impactors consisting of paint chips and bits of metal were identified on surfaces from LDEF Rows 3 (west or trailing side), 6 (south), 9 (ram or leading side), 12 (north) and the space end. Higher than expected ratios of manmade microparticle impacts to total microparticle impacts were found on the space end and the trailing side. These results were consistent with time-tagged and time-segregated microparticle impact data from the IDE and other LDEF experiments. A myriad of contamination interferences were identified and their effects on impactor debris identification mitigated during the course of this study. These interferences include pre-, post and inflight deposited surface contaminants as well as indigenous heterogeneous material contaminants. Non-flight contaminations traced to human origins, including spittle and skin oils, contributed significant levels of alkali-rich carbonaceous interferences. A ubiquitous layer of in-flight deposited silicaceous contamination varied in thickness with location on LDEF, even on a micro scale. In-flight deposited (low velocity) contaminants include urine droplets and bits of metal film from eroded thermal

  8. Fuzzy jets

    DOE PAGESBeta

    Mackey, Lester; Nachman, Benjamin; Schwartzman, Ariel; Stansbury, Conrad

    2016-06-01

    Here, collimated streams of particles produced in high energy physics experiments are organized using clustering algorithms to form jets . To construct jets, the experimental collaborations based at the Large Hadron Collider (LHC) primarily use agglomerative hierarchical clustering schemes known as sequential recombination. We propose a new class of algorithms for clustering jets that use infrared and collinear safe mixture models. These new algorithms, known as fuzzy jets , are clustered using maximum likelihood techniques and can dynamically determine various properties of jets like their size. We show that the fuzzy jet size adds additional information to conventional jet taggingmore » variables in boosted topologies. Furthermore, we study the impact of pileup and show that with some slight modifications to the algorithm, fuzzy jets can be stable up to high pileup interaction multiplicities.« less

  9. Fuzzy jets

    NASA Astrophysics Data System (ADS)

    Mackey, Lester; Nachman, Benjamin; Schwartzman, Ariel; Stansbury, Conrad

    2016-06-01

    Collimated streams of particles produced in high energy physics experiments are organized using clustering algorithms to form jets. To construct jets, the experimental collaborations based at the Large Hadron Collider (LHC) primarily use agglomerative hierarchical clustering schemes known as sequential recombination. We propose a new class of algorithms for clustering jets that use infrared and collinear safe mixture models. These new algorithms, known as fuzzy jets, are clustered using maximum likelihood techniques and can dynamically determine various properties of jets like their size. We show that the fuzzy jet size adds additional information to conventional jet tagging variables in boosted topologies. Furthermore, we study the impact of pileup and show that with some slight modifications to the algorithm, fuzzy jets can be stable up to high pileup interaction multiplicities.

  10. Jet propagation through energetic materials

    SciTech Connect

    Pincosy, P; Poulsen, P

    2004-01-08

    In applications where jets propagate through energetic materials, they have been observed to become sufficiently perturbed to reduce their ability to effectively penetrate subsequent material. Analytical calculations of the jet Bernoulli flow provides an estimate of the onset and extent of such perturbations. Although two-dimensional calculations show the back-flow interaction pressure pulses, the symmetry dictates that the flow remains axial. In three dimensions the same pressure impulses can be asymmetrical if the jet is asymmetrical. The 3D calculations thus show parts of the jet having a significant component of radial velocity. On the average the downstream effects of this radial flow can be estimated and calculated by a 2D code by applying a symmetrical radial component to the jet at the appropriate position as the jet propagates through the energetic material. We have calculated the 3D propagation of a radio graphed TOW2 jet with measured variations in straightness and diameter. The resultant three-dimensional perturbations on the jet result in radial flow, which eventually tears apart the coherent jet flow. This calculated jet is compared with jet radiographs after passage through the energetic material for various material thickness and plate thicknesses. We noted that confinement due to a bounding metal plate on the energetic material extends the pressure duration and extent of the perturbation.

  11. Measurements of Shaped Charge Jet Velocity

    NASA Astrophysics Data System (ADS)

    Huang, Hongfa

    2013-06-01

    Penetration depth is an important requirement in oil/gas well perforating jobs. The depth determines how far the wellbore can directly communicate with reservoir fluids. Deep perforation charges are widely used in oilfield industry and most of those are powder metal liner charge for no carrot-like slug left as solid liner does. Comprehensive measurements for the powder metal liner shaped charge jet characteristics, namely, the jet density and velocity, are needed to predict the shaped charge performance and to plan the perforating job. This paper focuses on an experimental work of jet velocity measurements. A medium size of powder metal liner charges (27 grams HMX) is used in the tests. The powder jet shoots through a stack of limestone blocks with shorting switch set in between. Half inch air-gap between two blocks is design to provide space for jet traveling in air to record free fly velocity, meanwhile the jet penetration velocity in the limestone is measured. Aluminum foil switches are used to record the jet Time of Arrival (TOA). The charged switch shorted by the metal jet when it arrives. The shorting signal is recorded. The two velocities can be used to estimate the jet penetration effectiveness. A series of TOA tests show that jet velocity along its length linearly decreases from jet tip to tail until the stagnation points referring to which jet material moves in opposite direction.

  12. The intact capture of hypervelocity dust particles using underdense foams

    NASA Technical Reports Server (NTRS)

    Maag, Carl R.; Borg, J.; Tanner, William G.; Stevenson, T. J.; Bibring, J.-P.

    1994-01-01

    The impact of a hypervelocity projectile (greater than 3 km/s) is a process that subjects both the impactor and the impacted material to a large transient pressure distribution. The resultant stresses cause a large degree of fragmentation, melting, vaporization, and ionization (for normal densities). The pressure regime magnitude, however, is directly related to the density relationship between the projectile and target materials. As a consequence, a high-density impactor on a low-density target will experience the lowest level of damage. Historically, there have been three different approaches toward achieving the lowest possible target density. The first employs a projectile impinging on a foil or film of moderate density, but whose thickness is much less than the particle diameter. This results in the particle experiencing a pressure transient with both a short duration and a greatly reduced destructive effect. A succession of these films, spaced to allow nondestructive energy dissipation between impacts, will reduce the impactor's kinetic energy without allowing its internal energy to rise to the point where destruction of the projectile mass will occur. An added advantage to this method is that it yields the possibility of regions within the captured particle where a minimum of thermal modification has taken place. Polymer foams have been employed as the primary method of capturing particles with minimum degradation. The manufacture of extremely low bulk density materials is usually achieved by the introduction of voids into the material base. It must be noted, however, that a foam structure only has a true bulk density of the mixture at sizes much larger than the cell size, since for impact processes this is of paramount importance. The scale at which the bulk density must still be close to that of the mixture is approximately equal to the impactor. When this density criterion is met, shock pressures during impact are minimized, which in turn maximizes the

  13. Cosmic jets

    SciTech Connect

    Blandford, R.D.; Begelman, M.C.; Rees, M.J.

    1982-05-01

    Observations with radio telescopes have revealed that the center of many galaxies is a place of violent activity. This activity is often manifested in the production of cosmic jets. Each jet is a narrow stream of plasma that appears to squirt out of the center of a galaxy emitting radiowaves as it does so. New techniques in radio astronomy have shown how common jets are in the universe. These jets take on many different forms. The discovery of radio jets has helped in the understanding of the double structure of the majority of extragalactic radio sources. The morphology of some jets and explanations of how jets are fueled are discussed. There are many difficulties plaguing the investigation of jets. Some of these difficulties are (1) it is not known how much power the jets are radiating, (2) it is hard to tell whether a jet delieated by radio emission is identical to the region where ionized gas is flowing, and (3) what makes them. (SC)

  14. Identification of a jet-driven supernova remnant in the Small Magellanic Cloud: Possible evidence for the enhancement of bipolar explosions at low metallicity

    SciTech Connect

    Lopez, Laura A.; Castro, Daniel; Slane, Patrick O.; Ramirez-Ruiz, Enrico; Badenes, Carles

    2014-06-10

    Recent evidence has suggested that the supernova remnant (SNR) 0104–72.3 in the Small Magellanic Cloud (SMC) may be the result of a 'prompt' Type Ia SN on the basis of enhanced iron abundances and its association with a star-forming region. In this paper, we present evidence that SNR 0104–72.3 arose from a jet-driven bipolar core-collapse (CC) SN. Specifically, we use serendipitous Chandra data of SNR 0104–72.3 taken because of its proximity to the calibration source SNR E0102–72.3. We analyze 56 Advanced CCD Imaging Spectrometer (ACIS) observations of SNR 0104–72.3 to produce imaging and spectra with an effective exposure of 528.6 ks. We demonstrate that SNR 0104–72.3 is highly elliptical relative to other nearby young SNRs, suggesting a CC SN origin. Furthermore, we compare ejecta abundances derived from spectral fits to nucleosynthetic yields of Type Ia and CC SNe, and we find that the iron, neon, and silicon abundances are consistent with either a spherical CC SN of a 18-20 M {sub ☉} progenitor or an aspherical CC SN of a 25 M {sub ☉} progenitor. We show that the star formation history at the site of SNR 0104–72.3 is also consistent with a CC origin. Given the bipolar morphology of the SNR, we favor the aspherical CC SN scenario. This result may suggest jet-driven SNe occur frequently in the low-metallicity environment of the SMC, consistent with the observational and theoretical work on broad-line Type Ic SNe and long-duration gamma-ray bursts.

  15. Hypervelocity star candidates in the SEGUE G and K dwarf sample

    SciTech Connect

    Palladino, Lauren E.; Holley-Bockelmann, Kelly; Schlesinger, Katharine J.; Allende Prieto, Carlos; Beers, Timothy C.; Lee, Young Sun; Schneider, Donald P. E-mail: k.holley@vanderbilt.edu

    2014-01-01

    We present 20 candidate hypervelocity stars from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) G and K dwarf samples. Previous searches for hypervelocity stars have only focused on large radial velocities; in this study, we also use proper motions to select the candidates. We determine the hypervelocity likelihood of each candidate by means of Monte Carlo simulations, considering the significant errors often associated with high proper motion stars. We find that nearly half of the candidates exceed their escape velocities with at least 98% probability. Every candidate also has less than a 25% chance of being a high-velocity fluke within the SEGUE sample. Based on orbits calculated using the observed six-dimensional positions and velocities, few, if any, of these candidates originate from the Galactic center. If these candidates are truly hypervelocity stars, they were not ejected by interactions with the Milky Way's supermassive black hole. This calls for a more serious examination of alternative hypervelocity-star ejection scenarios.

  16. Electromagnetic diagnostic techniques for hypervelocity projectile detection, velocity measurement, and size characterization: Theoretical concept and first experimental test

    SciTech Connect

    Uhlig, W. Casey; Heine, Andreas

    2015-11-14

    A new measurement technique is suggested to augment the characterization and understanding of hypervelocity projectiles before impact. The electromagnetic technique utilizes magnetic diffusion principles to detect particles, measure velocity, and indicate relative particle dimensions. It is particularly suited for detection of small particles that may be difficult to track utilizing current characterization methods, such as high-speed video or flash radiography but can be readily used for large particle detection, where particle spacing or location is not practical for other measurement systems. In this work, particles down to 2 mm in diameter have been characterized while focusing on confining the detection signal to enable multi-particle characterization with limited particle-to-particle spacing. The focus of the paper is on the theoretical concept and the analysis of its applicability based on analytical and numerical calculation. First proof-of-principle experimental tests serve to further validate the method. Some potential applications are the characterization of particles from a shaped-charge jet after its break-up and investigating debris in impact experiments to test theoretical models for the distribution of particles size, number, and velocity.

  17. Electromagnetic diagnostic techniques for hypervelocity projectile detection, velocity measurement, and size characterization: Theoretical concept and first experimental test

    NASA Astrophysics Data System (ADS)

    Uhlig, W. Casey; Heine, Andreas

    2015-11-01

    A new measurement technique is suggested to augment the characterization and understanding of hypervelocity projectiles before impact. The electromagnetic technique utilizes magnetic diffusion principles to detect particles, measure velocity, and indicate relative particle dimensions. It is particularly suited for detection of small particles that may be difficult to track utilizing current characterization methods, such as high-speed video or flash radiography but can be readily used for large particle detection, where particle spacing or location is not practical for other measurement systems. In this work, particles down to 2 mm in diameter have been characterized while focusing on confining the detection signal to enable multi-particle characterization with limited particle-to-particle spacing. The focus of the paper is on the theoretical concept and the analysis of its applicability based on analytical and numerical calculation. First proof-of-principle experimental tests serve to further validate the method. Some potential applications are the characterization of particles from a shaped-charge jet after its break-up and investigating debris in impact experiments to test theoretical models for the distribution of particles size, number, and velocity.

  18. Water Jetting

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Hi-Tech Inc., a company which manufactures water jetting equipment, needed a high pressure rotating swivel, but found that available hardware for the system was unsatisfactory. They were assisted by Marshall, which had developed water jetting technology to clean the Space Shuttles. The result was a completely automatic water jetting system which cuts rock and granite and removes concrete. Labor costs have been reduced; dust is suppressed and production has been increased.

  19. Cosmic jets

    NASA Technical Reports Server (NTRS)

    Rees, M. J.

    1986-01-01

    The evidence that active galactic nuclei produce collimated plasma jets is summarised. The strongest radio galaxies are probably energised by relativistic plasma jets generated by spinning black holes interacting with magnetic fields attached to infalling matter. Such objects can produce e(+)-e(-) plasma, and may be relevant to the acceleration of the highest-energy cosmic ray primaries. Small-scale counterparts of the jet phenomenon within our own galaxy are briefly reviewed.

  20. MMT HYPERVELOCITY STAR SURVEY. II. FIVE NEW UNBOUND STARS

    SciTech Connect

    Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. E-mail: mgeller@cfa.harvard.edu

    2012-05-20

    We present the discovery of five new unbound hypervelocity stars (HVSs) in the outer Milky Way halo. Using a conservative estimate of Galactic escape velocity, our targeted spectroscopic survey has now identified 16 unbound HVSs as well as a comparable number of HVSs ejected on bound trajectories. A Galactic center origin for the HVSs is supported by their unbound velocities, the observed number of unbound stars, their stellar nature, their ejection time distribution, and their Galactic latitude and longitude distribution. Other proposed origins for the unbound HVSs, such as runaway ejections from the disk or dwarf galaxy tidal debris, cannot be reconciled with the observations. An intriguing result is the spatial anisotropy of HVSs on the sky, which possibly reflects an anisotropic potential in the central 10-100 pc region of the Galaxy. Further progress requires measurement of the spatial distribution of HVSs over the southern sky. Our survey also identifies seven B supergiants associated with known star-forming galaxies; the absence of B supergiants elsewhere in the survey implies there are no new star-forming galaxies in our survey footprint to a depth of 1-2 Mpc.

  1. Hypervelocity Impact Testing of Space Station Freedom Solar Cells

    NASA Technical Reports Server (NTRS)

    Christie, Robert J.; Best, Steve R.; Myhre, Craig A.

    1994-01-01

    Solar array coupons designed for the Space Station Freedom electrical power system were subjected to hypervelocity impacts using the HYPER facility in the Space Power Institute at Auburn University and the Meteoroid/Orbital Debris Simulation Facility in the Materials and Processes Laboratory at the NASA Marshall Space Flight Center. At Auburn, the solar cells and array blanket materials received several hundred impacts from particles in the micron to 100 micron range with velocities typically ranging from 4.5 to 10.5 km/s. This fluence of particles greatly exceeds what the actual components will experience in low earth orbit. These impacts damaged less than one percent of total area of the solar cells and most of the damage was limited to the cover glass. There was no measurable loss of electrical performance. Impacts on the array blanket materials produced even less damage and the blanket materials proved to be an effective shield for the back surface of the solar cells. Using the light gas gun at MSFC, one cell of a four cell coupon was impacted by a 1/4 inch spherical aluminum projectile with a velocity of about 7 km/s. The impact created a neat hole about 3/8 inch in diameter. The cell and coupon were still functional after impact.

  2. Impact sensor network for detection of hypervelocity impacts on spacecraft

    NASA Astrophysics Data System (ADS)

    Schäfer, Frank; Janovsky, Rolf

    2007-11-01

    With regard to hypervelocity impact detection, a sensor network that can be applied on typical spacecraft structures is under development at Fraunhofer EMI (Ernst-Mach-Institut), supported by OHB-System. For impact detection, acoustic transducers are used. The structure types investigated are a 2 mm thick plate from aluminium alloy and a 49 mm thick sandwich panel with aluminium face-sheets and aluminium honeycomb core. One impact test was performed on each of the panels, which were instrumented with 6 ultrasonic transducers. The signals recorded at the various sensor locations varied with regard to peak amplitude and elapse time of the signal. Using this information and combining it with a localization algorithm, the impact location could be successfully determined. A description of the impact sensor network and the mathematical model to determine the impact location is provided. The impact tests on the spacecraft structure, the response of the sensor network and the analysis performed to determine the impact location are described.

  3. THE FIRST HYPERVELOCITY STAR FROM THE LAMOST SURVEY

    SciTech Connect

    Zheng, Zheng; Carlin, Jeffrey L.; Newberg, Heidi Jo; Beers, Timothy C.; Deng, Licai; Zhang, Haotong; Liu, Chao; Grillmair, Carl J.; Guhathakurta, Puragra; Yanny, Brian; Jin, Ge; Zhang, Yong

    2014-04-20

    We report the first hypervelocity star (HVS) discovered from the LAMOST spectroscopic survey. It is a B-type star with a heliocentric radial velocity of about 620 km s{sup –1}, which projects to a Galactocentric radial velocity component of ∼477 km s{sup –1}. With a heliocentric distance of ∼13 kpc and an apparent magnitude of ∼13 mag, it is the closest bright HVS currently known. With a mass of ∼9 M {sub ☉}, it is one of the three most massive HVSs discovered so far. The star is clustered on the sky with many other known HVSs, and its position suggests a possible connection to Galactic center structures. With the current poorly determined proper motion, a Galactic center origin of this HVS remains consistent with the data at the 1σ level, while a disk runaway origin cannot be excluded. We discuss the potential of the LAMOST survey to discover a large statistical sample of HVSs of different types.

  4. Response of Hypervelocity Boundary Layers to Global and Local Distortion

    NASA Astrophysics Data System (ADS)

    Flaherty, William; Austin, Joanna

    2013-11-01

    Concave surface curvature can impose significant distortion to compressible boundary layer flows due to multiple, potentially coupled, effects including an adverse pressure gradient, bulk flow compression, and possible centrifugal instabilities. Approximate methods provide insight into dominant mechanisms, however few strategies are capable of treating heat transfer effects and predictions diverge significantly from the available experimental data at larger pressure gradient. In this work, we examine the response of boundary layers to global and local distortions in hypervelocity flows where thermochemical energy exchange has significant impact on boundary layer structure and stability. Experiments are carried out in a novel expansion tube facility built at Illinois. We demonstrate that reasonable estimates of the laminar heat flux augmentation may be obtained as a function of the local turning angle, even at the conditions of greatest distortion. As a model problem to study the evolution of large-scale structures under strained conditions, streamwise vortices are imposed into the boundary layer. The impact of the additional local distortion is investigated. The heat transfer scaling is found to be robust even in the presence of the imposed structures.

  5. Correlation between speed and size for ejecta from hypervelocity impacts

    NASA Astrophysics Data System (ADS)

    Sachse, M.; Schmidt, J.; Kempf, S.; Spahn, F.

    2015-11-01

    Ejecta created in hypervelocity impacts of micrometeoroids on atmosphereless bodies are an efficient source for circumplanetary and interplanetary dust. The impact erodes the target surface and releases material into space. The ejecta are typically micron sized and populate a dust cloud around the parent body, whose number density decreases with increasing distance from the target. Unbound particles escape and add to the planetary dust environment. Here we explore the influence of a correlation between the fragment size and the ejection speed, such that larger fragments are (on average) launched with lower speeds. This behavior is suggested by theoretical considerations and impact experiments. We find that such a correlation provides a dynamical filter that removes large ejecta from high altitudes. The effect is stronger for bigger ejecta and for more massive parent bodies. Our results suggest that large particles found in the circumplanetary and interplanetary dust environment either originate from impacts on smaller moons, impacts of unusually large or fast impactors, or an entirely different process of dust production.

  6. High pressure composite tank behaviour under an hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Salome, Roland; Albouys, Vincent; Le Floch, Christian; Sornette, Didier; Vila, Jean Paul

    2001-10-01

    Space debris represent a threat to spacecraft in near earth orbits and protection against them is a key requirement for the Space Station. Thus, regulations are being issued in order to prevent new debris generation from a spacecraft which can be impacted by a debris. Due to their risk of burst, pressurized vessels are classified as critical components, and high pressure composite overwrapped vessels are considered as specially critical. Furthermore, the design of a protection device is closely depending of the behaviour of the vessel under impact. CNES has started a R&D action in order to characterize the behaviour of a high pressure composite vessel under an hypervelocity impact. This study is managed by EADS/Launch vehicles in collaboration with Nice Sciences University and INSA Toulouse. The pressure vessel considered is an over-wrapped carbon fibre on a titanium liner loaded with xenon or helium under high pressure (15 Mpa or 31 Mpa). In a first phase, the theoretical approach to predict the tank behaviour consists in a 2D and 3D simulation using a SPH code (Smoothed Particle Hydrodynamics). An experimental validation of the numerical model will be conducted in the future.

  7. MMT hypervelocity star survey. III. The complete survey

    SciTech Connect

    Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J. E-mail: mgeller@cfa.harvard.edu

    2014-05-20

    We describe our completed spectroscopic survey for unbound hypervelocity stars (HVSs) ejected from the Milky Way. Three new discoveries bring the total number of unbound late B-type stars to 21. We place new constraints on the nature of the stars and on their distances using moderate resolution MMT spectroscopy. Half of the stars are fast rotators; they are certain 2.5-4 M {sub ☉} main sequence stars at 50-120 kpc distances. Correcting for stellar lifetime, our survey implies that unbound 2.5-4 M {sub ☉} stars are ejected from the Milky Way at a rate of 1.5 × 10{sup –6} yr{sup –1}. These unbound HVSs are likely ejected continuously over the past 200 Myr and do not share a common flight time. The anisotropic spatial distribution of HVSs on the sky remains puzzling. Southern hemisphere surveys like SkyMapper will soon allow us to map the all-sky distribution of HVSs. Future proper motion measurements with Hubble Space Telescope and Gaia will provide strong constraints on origin. Existing observations are all consistent with HVS ejections from encounters with the massive black hole in the Galactic center.

  8. Induction Heating of Hypervelocity Impact Samples to 2500 Degrees Centigrade

    NASA Technical Reports Server (NTRS)

    Simmons, Joshua; Pardo, Art; Henderson, Don; Rodriguez, Karen

    2014-01-01

    The Remote Hypervelocity Test Laboratory (RHTL) at White Sands Test Facility (WSTF) was asked to heat samples up to 2500 degrees Centigrade (4532 degrees Fahrenheit) to simulate reentry scenarios of crafts where heated shields are impacted with single small particles ranging from 0.2 to 1.0 millimeters (.008 to.039 inches) of various materials. The team decided an electromagnetic induction (induction heater) was the best method to achieve and control the temperatures in a rapid manner. The samples consisted of three-dimensional carbon-carbon and two-dimensional carbon-phenolic, which are both electrically conductive. After several attempts the team was able to achieve over 2500 degrees Centigrade (4532 degrees Fahrenheit) in ambient atmosphere. When the system was moved to the target chamber and the vacuum system evacuated down to 250 millitorr, arcing occurred between the bus bars and tank, the feedthrough fittings that carried the coolant and current, and between the target sample and coil. To overcome this arcing, conformal coatings, room temperature vulcanization (RTV) silicone, and other non-conductive materials were used to isolate the electromagnetic fields.

  9. An Exponential Luminous Efficiency Model for Hypervelocity Impact into Regolith

    NASA Technical Reports Server (NTRS)

    Swift, W. R.; Moser, D. E.; Suggs, R. M.; Cooke, W. J.

    2011-01-01

    The flash of thermal radiation produced as part of the impact-crater forming process can be used to determine the energy of the impact if the luminous efficiency is known. From this energy the mass and, ultimately, the mass flux of similar impactors can be deduced. The luminous efficiency, eta, is a unique function of velocity with an extremely large variation in the laboratory range of under 6 km/s but a necessarily small variation with velocity in the meteoric range of 20 to 70 km/s. Impacts into granular or powdery regolith, such as that on the moon, differ from impacts into solid materials in that the energy is deposited via a serial impact process which affects the rate of deposition of internal (thermal) energy. An exponential model of the process is developed which differs from the usual polynomial models of crater formation. The model is valid for the early time portion of the process and focuses on the deposition of internal energy into the regolith. The model is successfully compared with experimental luminous efficiency data from both laboratory impacts and from lunar impact observations. Further work is proposed to clarify the effects of mass and density upon the luminous efficiency scaling factors. Keywords hypervelocity impact impact flash luminous efficiency lunar impact meteoroid 1

  10. Enhanced magnetic field production during oblique hypervelocity impacts

    NASA Technical Reports Server (NTRS)

    Crawford, D. A.; Schultz, P. H.

    1992-01-01

    The natural remanent magnetization of the lunar surface as displayed in returned lunar samples and the data returned by the Apollo subsatellite magnetometer has an unexpectedly high magnitude and exhibits spatial variation at all scales. The origin of the lunar remanent fields may be due to crustal remanence of a core dynamo field occurring early in lunar history prior to extensive modification by impact or remanence of transient fields, particularly associated with impacts, occurring on a local scale throughout lunar history. The presence of an early core dynamo field would have strong consequences for the formation and early evolution of the Moon, yet to deconvolve the role that an internally generated core dynamo field may have had, it is necessary to understand how the magnetic state of the lunar surface has developed through time. Impact-induced magnetism may be an important component of the present magnetic state of the lunar surface. New theoretical considerations suggest that transient magnetic fields within plasma produced by hypervelocity meteorite impacts may have greater significance at larger scales than previously thought.

  11. Structural Damage Prediction and Analysis for Hypervelocity Impact

    NASA Technical Reports Server (NTRS)

    Elfer, Norman

    1995-01-01

    It is necessary to integrate a wide variety of technical disciplines to provide an analysis of structural damage to a spacecraft due to hypervelocity impact. There are many uncertainties, and more detailed investigation is warranted, in each technical discipline. However, a total picture of the debris and meteoroid hazard is required to support manned spaceflight in general, and the international Space Station in particular. In the performance of this contract, besides producing a handbook, research and development was conducted in several different areas. The contract was broken into six separate tasks. Each task objectives and accomplishments will be reviewed in the following sections. The Handbook and separate task reports are contained as attachments to the final report. The final section summarizes all of the recommendations coming out of this study. The analyses and comments are general design guidelines and not necessarily applicable to final Space Station designs since several configuration and detailed design changes were being made during the course of this contract. Rather, the analyses and comments may indicate either a point-in-time concept analysis, available test data, or desirable protection goals, not hindered by the design and operation constraints faced by Space Station designers.

  12. Discrete shear failure planes resulting from oblique hypervelocity impacts

    NASA Astrophysics Data System (ADS)

    Stickle, A. M.; Schultz, P. H.

    2014-08-01

    A combination of laboratory and numerical experiments examines the role of shear localization in subsurface damage following very oblique (15-30°) hypervelocity impacts. Laboratory experiments reveal subsurface damage planes ("blades") parallel to the impact trajectory for highly oblique impacts (15-30°), which are characterized by unique surface textures relative to other failure regions. Observations of growth rate and surface texture of the damage planes combined with three-dimensional CTH simulations indicate that the blades are the result of frictional processes during localized shear deformation. Laboratory experiments also reveal that impact angle and projectile failure play a role in the development of these blades: aluminum projectiles result in distinct along-trajectory blades for both 15° and 30° impacts, whereas the blades are weakly developed for Pyrex projectiles and nonexistent for planar polymethylmethacrylate projectiles. The blades form early in the cratering process and are signatures of the projectile momentum being transferred into the target. Based on the growth rate, and melting seen along the surface of these damage planes, the blades may provide an analog for the generation of pseudotachylytes during the early stages of impact crater formation.

  13. Oblique hypervelocity impact response of dual-sheet structures

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Taylor, Roy A.

    1989-01-01

    The results of a continuing investigation of the phenomena associated with the oblique hypervelocity impact of spherical projectiles onto multi-sheet aluminum structures are given. A series of equations that quantitatively describes these phenomena is obtained through a regression of experimental data. These equations characterize observed ricochet and penetration damage phenomena in a multi-sheet structure as functions of geometric parameters of the structure and the diameter, obliquity, and velocity of the impacting projectile. Crater damage observed on the ricochet witness plates is used to determine the sizes and speeds of the ricochet debris particles that caused the damage. It is observed that the diameter of the most damaging ricochet debris particle can be as large as 40 percent of the original particle diameter and can travel at speeds between 24 percent and 36 percent of the original projectile impact velocity. The equations necessary for the design of shielding panels that will protect external systems from such ricochet debris damage are also developed. The dimensions of these shielding panels are shown to be strongly dependent on their inclination and on their circumferential distribution around the spacecraft.

  14. Debris area distribution of spacecraft under hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Lan, Sheng-wei; Liu, Sen; Li, Yi; Ke, Fa-wei; Huang, Jie

    2014-12-01

    Cross-sectional area is an important parameter for spacecraft breakup debris as it is the directly measured data in space observation. It is significant for observing and analysing the spacecraft breakup event to accurately modelling the area distribution of the breakup debris. In this paper, experimental study has been performed on debris area distribution characteristics of spacecraft under hypervelocity impact. The tests are carried out at the ballistic ranges of CARDC. Aluminium projectiles are launched to normally impact the simulated spacecrafts at about 3.0 km/s. The simulated spacecrafts are made up of aluminium plates, filled with some simulated electronics boxes, each of which was installed with a circuit board. "Soft-catch" devices are used to recover the breakup fragments. The test results show that: 1) the relationship between the cross-sectional area and the characteristic length of debris, which can be obtained in the logarithmic coordinates by linear fitting, represents the debris shape characteristic in a certain extent; 2) the area-to-mass ratios of fragments show normal distributions in the logarithmic coordinates; 3) debris made of different materials can be distinguished by different peaks on the distribution curves; 4) the area-to-mass ratio distributions can be expressed by a linear superimposition of several normal functions which represent the main materials of the spacecraft.

  15. Hypervelocity Impact Test Facility: A gun for hire

    NASA Technical Reports Server (NTRS)

    Johnson, Calvin R.; Rose, M. F.; Hill, D. C.; Best, S.; Chaloupka, T.; Crawford, G.; Crumpler, M.; Stephens, B.

    1994-01-01

    An affordable technique has been developed to duplicate the types of impacts observed on spacecraft, including the Shuttle, by use of a certified Hypervelocity Impact Facility (HIF) which propels particulates using capacitor driven electric gun techniques. The fully operational facility provides a flux of particles in the 10-100 micron diameter range with a velocity distribution covering the space debris and interplanetary dust particle environment. HIF measurements of particle size, composition, impact angle and velocity distribution indicate that such parameters can be controlled in a specified, tailored test designed for or by the user. Unique diagnostics enable researchers to fully describe the impact for evaluating the 'targets' under full power or load. Users regularly evaluate space hardware, including solar cells, coatings, and materials, exposing selected portions of space-qualified items to a wide range of impact events and environmental conditions. Benefits include corroboration of data obtained from impact events, flight simulation of designs, accelerated aging of systems, and development of manufacturing techniques.

  16. Hypervelocity Heat-Transfer Measurements in an Expansion Tube

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Perkins, John N.

    1996-01-01

    A series of experiments has been conducted in the NASA HYPULSE Expansion Tube, in both CO2 and air test gases, in order to obtain data for comparison with computational results and to assess the capability for performing hypervelocity heat-transfer studies in this facility. Heat-transfer measurements were made in both test gases on 70 deg sphere-cone models and on hemisphere models of various radii. HYPULSE freestream flow conditions in these test gases were found to be repeatable to within 3-10%, and aerothermodynamic test times of 150 microsec in CO2 and 125 microsec in air were identified. Heat-transfer measurement uncertainty was estimated to be 10-15%. Comparisons were made with computational results from the non-equilibrium Navier-Stokes solver NEQ2D. Measured and computed heat-transfer rates agreed to within 10% on the hemispheres and on the sphere-cone forebodies, and to within 10% in CO2 and 25% in air on the afterbodies and stings of the sphere-cone models.

  17. Projectile development for railguns using hypervelocity preacceleration. Revision 1

    SciTech Connect

    Susoeff, A.R.; Hawke, R.S.; Ang, J.A.; Asay, J.R.; Hall, C.A.; Konrad, C.H.; Sauve, G.L.; Hickman, R.J.

    1992-03-20

    The STARFIRE Project is a joint Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories (SNL) effort to achieve hypervelocity projectile launches up to 15 km/s. The apparatus used to achieve this goal is a three stage acceleration system made up of a two-stage light-gas gun (2SLGG) coupled to a railgun. The 2SLGG is used as a preaccelerator capable of injecting 2 gram projectiles at velocities of 6 km/s or more. Projectiles used in this environment are subject to many conditions. Some of these which effect projectile design include: acceleration loading, structural response, barrel condition and alignment. Development of a projectile to satisfy the programmatic requirements is underway. This report covers the evolution of design and fabrication for railgun projectiles from previous experiment at LLNL to the replenished plasma armature and projectile now used on STARFIRE. Projectile design, development and fabrication methods which use off-the-shelf materials and standard techniques to meet the operational criteria of the experimental program are discussed in this paper. Initial work involving the design and fabrication of skirted projectiles, which are expected to further reduce interaction phenomena between the plasma armature and railgun barrel, is also described.

  18. The effect of simulated hypervelocity space debris on polymers

    SciTech Connect

    Verker, R. . E-mail: rverker@soreq.gov.il; Eliaz, N.; Gouzman, I.; Eliezer, S.; Fraenkel, M.; Maman, S.; Beckmann, F.; Pranzas, K.; Grossman, E.

    2004-11-08

    Space debris population in low Earth orbit has been increasing constantly with the increase in spacecraft missions. Hypervelocity space debris impacts limit the functionality of polymeric outer surfaces and, in extreme cases, might cause a total loss of a spacecraft. In this work, the fracture of Kapton films by ultrahigh velocity impacts was studied. A laser-driven flyer ground simulation system was used to accelerate aluminum flyers to impact velocities as high as 2.9 km/s against polymer films with different thicknesses. Scanning electron microscopy was used to characterize the fracture morphology. Impact effects on the internal structure of the polymer were studied by means of X-ray microtomography. It was found that with an increase in debris velocity, a ductile-to-brittle transition occurred. However, fractures created by impacts at velocities above 1.7 km/s showed central impacts regions, which experienced the highest strain rate and were of ductile-type fracture, while the outer regions, which experienced a lower strain rate, failed through brittle cracking. A model explaining this phenomenon, based on the temperature gradient developed within the impacted region during collision, is presented.

  19. Large Eddy Simulation of Mixing within a Hypervelocity Scramjet Combustor

    NASA Astrophysics Data System (ADS)

    Petty, David; Wheatley, Vincent; Pantano, Carlos; Smart, Michael

    2013-11-01

    The turbulent mixing of parallel hypervelocity (U = 3230 m/sec, M = 3.86) air-streams with a sonic stream of gaseous hydrogen is simulated using large eddy simulation. The resultant mixing layers are characterized by a convective Mach number of 1.20. This configuration represents parallel slot injection of hydrogen via an intrusive centerbody within a constant area rectangular combustor. A hybrid shock-capturing/zero numerical dissipation (WENO/TCD) switch method designed for simulations of compressible turbulent flows was utilized. Sub-grid scale turbulence was modeled using the stretched vortex model. Visualizations of the three dimensional turbulent structures generated behind the centerbody will be presented. It has been observed that a span-wise instability of the wake behind the centerbody is initially dominant. Further downstream, the shear-layers coalesce into a mixing wake and develop the expected large-scale coherent span-wise vortices. Ph.D. Candidate, School of Mechanical and Mining Engineering, Centre for Hypersonics.

  20. Modelling hypervelocity impacts into aluminum structures based on LDEF data

    NASA Technical Reports Server (NTRS)

    Coombs, C. R.; Atkinson, D. R.; Watts, A. J.; Wagner, J. R.; Allbrooks, M. K.; Hennessy, C. J.

    1993-01-01

    Realizing and understanding the effects of the near-Earth space environment on a spacecraft during its mission lifetime is becoming more important with the regeneration of America's space program. Included among these potential effects are the following: erosion and surface degradation due to atomic oxygen impingement; ultraviolet exposure embrittlement; and delamination, pitting, cratering, and ring formation due to micrometeoroid and debris impacts. These effects may occur synergistically and may alter the spacecraft materials enough to modify the resultant crater, star crack, and/or perforation. This study concentrates on modelling the effects of micrometeoroid and debris hypervelocity impacts into aluminum materials (6061-T6). Space debris exists in all sizes, and has the possibility of growing into a potentially catastrophic problem, particularly since self-collisions between particles can rapidly escalate the number of small impactors. We have examined the morphologies of the Long Duration Exposure Facility (LDEF) impact craters and the relationship between the observed impact damage on LDEF versus the existing models for both the natural (micrometeoroid) and manmade (debris) environments in order to better define these environments.

  1. Characterization of space station multilayer insulation damage due to hypervelocity space debris impact

    NASA Technical Reports Server (NTRS)

    Rule, William Keith

    1990-01-01

    Four main tasks were accomplished. The first three tasks were related to the goal of measuring the degradation of the insulating capabilities of Space Station multilayer insulation (MLI) due to simulated space debris impacts at hypervelocities. The last task was associated with critically reviewing a Boeing document on the fracture characteristics of the Space Station pressure wall when subjected to a simulated hypervelocity space debris impact. In Task 1, a thermal test procedure for impact damaged MLI specimens was written. In Task 2, damaged MLI specimens were prepared. In Task 3, a computer program was written to simulate MLI thermal tests. In Task 4, the author reviewed a Boeing document describing hypervelocity impact testing on biaxially stressed plates.

  2. Investigation on plasma generated during hypervelocity impact at different impact velocities and angles

    SciTech Connect

    Song, Weidong Lv, Yangtao; Wang, Cheng; Li, Jianqiao

    2015-12-15

    A 3D Smoothed Particle Hydrodynamics code was developed to investigate plasma generation by considering a chemical reaction process in hypervelocity impacts of an aluminum projectile on an aluminum target. The chemical reaction process was described by the reaction rate based on the Arrhenius equation and used to calculate the plasma generation during the impact simulation. The predicted result was verified by empirical formulas and a new empirical formula was proposed based on the comparisons and analyses. The influence of the impact angle was discussed for different impact velocities. Then, the application of both the new and original empirical formulas for protection design from plasma generated by hypervelocity impact was discussed, which demonstrated that the code and model were useful in the prediction of hypervelocity impacts on spacecraft.

  3. An analysis of penetration and ricochet phenomena in oblique hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Taylor, Roy A.; Horn, Jennifer R.

    1988-01-01

    An experimental investigation of phenomena associated with the oblique hypervelocity impact of spherical projectiles on multisheet aluminum structures is described. A model that can be employed in the design of meteoroid and space debris protection systems for space structures is developed. The model consists of equations that relate crater and perforation damage of a multisheet structure to parameters such as projectile size, impact velocity, and trajectory obliquity. The equations are obtained through a regression analysis of oblique hypervelocity impact test data. This data shows that the response of a multisheet structure to oblique impact is significantly different from its response to normal hypervelocity impact. It was found that obliquely incident projectiles produce ricochet debris that can severely damage panels or instrumentation located on the exterior of a space structure. Obliquity effects of high-speed impact must, therefore, be considered in the design of any structure exposed to the meteoroid and space debris environment.

  4. Investigation on plasma generated during hypervelocity impact at different impact velocities and angles

    NASA Astrophysics Data System (ADS)

    Song, Weidong; Lv, Yangtao; Wang, Cheng; Li, Jianqiao

    2015-12-01

    A 3D Smoothed Particle Hydrodynamics code was developed to investigate plasma generation by considering a chemical reaction process in hypervelocity impacts of an aluminum projectile on an aluminum target. The chemical reaction process was described by the reaction rate based on the Arrhenius equation and used to calculate the plasma generation during the impact simulation. The predicted result was verified by empirical formulas and a new empirical formula was proposed based on the comparisons and analyses. The influence of the impact angle was discussed for different impact velocities. Then, the application of both the new and original empirical formulas for protection design from plasma generated by hypervelocity impact was discussed, which demonstrated that the code and model were useful in the prediction of hypervelocity impacts on spacecraft.

  5. Multi-shock assembly for protecting a spacecraft surface from hypervelocity impactors

    NASA Technical Reports Server (NTRS)

    Dvorak, Bruce D. (Inventor)

    2001-01-01

    A hypervelocity impact shield assembly for protecting a spacecraft surface from hypervelocity impactors. The shield assembly includes at least one sacrificial impactor disrupting/shocking layer of hypervelocity impactor disrupting/shocking material. A primary spacing element, including space-rated open cell foam material, is positioned between the at least one sacrificial impactor disrupting/shocking layer and a spacecraft surface. A cover member is arranged and disposed relative to the sacrificial impactor disrupting/shocking layer and the primary spacing element to maintain the integrity of the hypervelocity impact shield assembly. In the event of exposure to a hypervelocity impactor, the sacrificial impactor disrupting/shocking layer is perforated while shocking the impactor breaking it into fragments, and/or melting it, and/or vaporizing it, thus providing a dispersion in the form of an expanding debris cloud/plume which spreads the impact energy of the impactor over a volume formed by the primary spacing element between the sacrificial impactor disrupting/shocking layer and the spacecraft surface. This significantly reduces impact lethality at the spacecraft surface. The space-rated open cell foam material provides an extremely lightweight, low-cost, efficient means of spacing and supporting the at least one sacrificial impactor disrupting/shocking layer before, during, and after launch. In a preferred embodiment, the invention is in the form of a multi-shock assembly including a plurality of sacrificial impactor disrupting/shocking layers. In such instance, the hypervelocity impact shield assembly includes a plurality of secondary spacing elements. Each secondary spacing element is positioned adjacent an associated sacrificial impactor disrupting/shocking layer to form a multi-shock subassembly. Thus, a plurality of multi-shock subassemblies are provided which include alternating layers of sacrificial impactor disrupting/shocking layers and secondary spacing

  6. Geochemical processes between steel projectiles and silica-rich targets in hypervelocity impact experiments

    NASA Astrophysics Data System (ADS)

    Ebert, Matthias; Hecht, Lutz; Deutsch, Alexander; Kenkmann, Thomas; Wirth, Richard; Berndt, Jasper

    2014-05-01

    The possibility of fractionation processes between projectile and target matter is critical with regard to the classification of the impactor type from geochemical analysis of impactites from natural craters. Here we present results of five hypervelocity MEMIN impact experiments (Poelchau et al., 2013) using the Cr-V-Co-Mo-W-rich steel D290-1 as projectile and two different silica-rich lithologies (Seeberger sandstone and Taunus quartzite) as target materials. Our study is focused on geochemical target-projectile interaction occurring in highly shocked and projectile-rich ejecta fragments. In all of the investigated impact experiments, whether sandstone or quartzite targets, the ejecta fragments show (i) shock-metamorphic features e.g., planar-deformation features (PDF) and the formation of silica glasses, (ii) partially melting of projectile and target, and (iii) significant mechanical and chemical mixing of the target rock with projectile material. The silica-rich target melts are strongly enriched in the "projectile tracer elements" Cr, V, and Fe, but have just minor enrichments of Co, W, and Mo. Inter-element ratios of these tracer elements within the contaminated target melts differ strongly from the original ratios in the steel. The fractionation results from differences in the reactivity of the respective elements with oxygen during interaction of the metal melt with silicate melt. Our results indicate that the principles of projectile-target interaction and associated fractionation do not depend on impact energies (at least for the selected experimental conditions) and water-saturation of the target. Partitioning of projectile tracer elements into the silicate target melt is much more enhanced in experiments with a non-porous quartzite target compared with the porous sandstone target. This is mainly the result of higher impact pressures, consequently higher temperatures and longer reaction times at high temperatures in the experiments with quartzite as

  7. Hypervelocity Impact (HVI). Volume 4; WLE Small-Scale Fiberglass Panel Flat Target C-2

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target C-2 was to study impacts through the reinforced carboncarbon (RCC) panels of the Wing Leading Edge. Fiberglass was used in place of RCC in the initial tests. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  8. Computational modeling of electrostatic charge and fields produced by hypervelocity impact

    SciTech Connect

    Crawford, David A.

    2015-05-19

    Following prior experimental evidence of electrostatic charge separation, electric and magnetic fields produced by hypervelocity impact, we have developed a model of electrostatic charge separation based on plasma sheath theory and implemented it into the CTH shock physics code. Preliminary assessment of the model shows good qualitative and quantitative agreement between the model and prior experiments at least in the hypervelocity regime for the porous carbonate material tested. The model agrees with the scaling analysis of experimental data performed in the prior work, suggesting that electric charge separation and the resulting electric and magnetic fields can be a substantial effect at larger scales, higher impact velocities, or both.

  9. Hypervelocity impact induced arcing and Kapton pyrolization in a plasma environment

    NASA Astrophysics Data System (ADS)

    Christie, Robert J.; Best, Steve R.; Myhre, Craig A.

    1994-03-01

    Tests were performed on the Space Station Freedom (SSF) solar array flat conductor circuit (FCC) to determine if hypervelocity impacts could induce pyrolization of Kapton and/or cross-conductor arcing. A sample piece of FCC was placed in a plasma environment and biased to +200 V relative to the plasma potential. The FCC was then impacted with particles in the 100 micron size range with hypervelocities of about 7 km/s. These tests were unable to induce Kapton pyrolization, cross-conductor arcing, or any other plasma interaction.

  10. A Study of Premixed, Shock-Induced Combustion With Application to Hypervelocity Flight

    NASA Technical Reports Server (NTRS)

    Axdahl, Erik L.

    2013-01-01

    One of the current goals of research in hypersonic, airbreathing propulsion is access to higher Mach numbers. A strong driver of this goal is the desire to integrate a scramjet engine into a transatmospheric vehicle airframe in order to improve performance to low Earth orbit (LEO) or the performance of a semiglobal transport. An engine concept designed to access hypervelocity speeds in excess of Mach 10 is the shock-induced combustion ramjet (i.e. shcramjet). This dissertation presents numerical studies simulating the physics of a shcramjet vehicle traveling at hypervelocity speeds with the goal of understanding the physics of fuel injection, wall autoignition mitigation, and combustion instability in this flow regime.

  11. Unconditional jetting.

    PubMed

    Gañán-Calvo, Alfonso M

    2008-08-01

    Capillary jetting of a fluid dispersed into another immiscible phase is usually limited by a critical capillary number, a function of the Reynolds number and the fluid property ratios. Critical conditions are set when the minimum spreading velocity of small perturbations v_{-};{*} along the jet (marginal stability velocity) is zero. Here we identify and describe parametric regions of high technological relevance, where v_{-};{*}>0 and the jet flow is always supercritical independently of the dispersed liquid flow rate; within these relatively broad regions, the jet does not undergo the usual dripping-jetting transition, so that either the jet can be made arbitrarily thin (yielding droplets of any imaginably small size), or the issuing flow rate can be made arbitrarily small. In this work, we provide illustrative analytical studies of asymptotic cases for both negligible and dominant inertia forces. In this latter case, requiring a nonzero jet surface velocity, axisymmetric perturbation waves "surf" downstream for all given wave numbers, while the liquid bulk can remain static. In the former case (implying small Reynolds flow) we found that the jet profile small slope is limited by a critical value; different published experiments support our predictions. PMID:18850933

  12. ON THE SPATIAL DISTRIBUTION AND THE ORIGIN OF HYPERVELOCITY STARS

    SciTech Connect

    Lu Youjun; Zhang Fupeng; Yu Qingjuan E-mail: fpzhang@bao.ac.c

    2010-02-01

    Hypervelocity stars (HVSs) escaping away from the Galactic halo are dynamical products of interactions of stars with the massive black hole(s) (MBH) in the Galactic Center (GC). They are mainly B-type stars with their progenitors unknown. OB stars are also populated in the GC, with many being hosted in a clockwise-rotating young stellar (CWS) disk within half a parsec from the MBH and their formation remaining puzzles. In this paper, we demonstrate that HVSs can well memorize the injecting directions of their progenitors using both analytical arguments and numerical simulations, i.e., the ejecting direction of an HVS is almost anti-parallel to the injecting direction of its progenitor. Therefore, the spatial distribution of HVSs maps the spatial distribution of the parent population of their progenitors directly. We also find that almost all the discovered HVSs are spatially consistent with being located on two thin disk planes. The orientation of one plane is consistent with that of the (inner) CWS disk, which suggests that most of the HVSs originate from the CWS disk or a previously existed disk-like stellar structure with an orientation similar to it. The rest of HVSs may be correlated with the plane of the northern arm of the mini-spiral in the GC or the plane defined by the outer warped part of the CWS disk. Our results not only support the GC origin of HVSs but also imply that the central disk (or the disk structure with a similar orientation) should persist or be frequently rejuvenated over the past 200 Myr, which adds a new challenge to the stellar disk formation and provides insights to the longstanding problem of gas fueling into MBHs.

  13. Hypervelocity impact survivability experiments for carbonaceous impactors, part 2

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Paque, Julie M.; Becker, Luann; Vedder, James F.; Erlichman, Jozef

    1995-01-01

    Hypervelocity impact experiments were performed to further test the survivability of carbonaceous impactors and to determine potential products that may have been synthesized during impact. Diamonds were launched by the Ames two-stage light gas gun into Al plate at velocities of 2.75 and 3.1 km sec(exp -1). FESEM imagery confirms that diamond fragments survived in both experiments. Earlier experiments found that diamonds were destroyed on impact above 4.3 km sec(exp -1). Thus, the upper stability limit for diamond on impact into Al, as determined from our experimental conditions, is between 3.1 and 4.3 km sec(exp -1). Particles of the carbonaceous chondrite Nogoya were also launched into Al at a velocity of 6.2 km sec (exp -1). Laser desorption (L (exp 2) MS) analyses of the impactor residues indicate that the lowest and highest mass polycyclic aromatic hydrocarbons (PAH's) were largely destroyed on impact; those of intermediate mass (202-220 amu) remained at the same level or increased in abundance. In addition, alkyl-substituted homologs of the most abundant pre-impacted PAH's were synthesized during impact. These results suggest that an unknown fraction of some organic compounds can survive low to moderate impact velocities and that synthesized products can be expected to form up to velocities of, at least, 6.5 km sec(exp -1). We also present examples of craters formed by a unique microparticle accelerator that could launch micron-sized particles of almost any coherent material at velocities up to approximately 15 km sec(exp -1). Many of the experiments have a direct bearing on the interpretation of LDEF craters.

  14. Hypervelocity capture of particles in aerogel: Dependence on aerogel properties

    NASA Astrophysics Data System (ADS)

    Burchell, M. J.; Fairey, S. A. J.; Foster, N. J.; Cole, M. J.

    2009-01-01

    Capture of high-speed (hypervelocity) particles in aerogel at ambient temperatures of 175-763 K is reported. This extends previous work which has mostly focussed on conducting experiments at ambient laboratory temperatures, even though aerogels are intended for use in cosmic dust capture cells in space environments which may experience a range of temperatures (e.g., the NASA Stardust mission which collected dust at 1.81 AU and putative Mars atmospheric sampling missions). No significant change in track length (normalised to impactor size) was found over the range 175-600 K, although at 763 K a significant reduction (30%) was found. By contrast, entrance hole diameter remained constant only up to 400 K, above this sudden changes of up to 50% were observed. Experiments were also carried out at normal laboratory temperature using a wide range of aerogel densities and particle sizes. It was found that track length normalised to particle size varies inversely with aerogel density. This is a power law dependence and not linear as previously reported, with longer tracks at lower densities. Glass projectiles (up to 100 μm size) were found to undergo a variety of degrees of damage during capture. In addition to the well known acquisition of a coating (partial or complete) of molten aerogel the mechanical damage includes pitting and meridian fractures. Larger (500 μm diameter) stainless steel spheres also showed damage during capture. In this case melting and ablation occurs, suggesting surficial temperatures during impact in excess of 1400 °C. The response of the aerogel itself to passage of particles through it is reported. The presence of fan-like fractures around the tracks is attributed to cone cracking similar to that in glasses of normal density, with the difference that here it is a repetitive process as the particles pass through the aerogel.

  15. Detection of meteoroid hypervelocity impacts on the Cluster spacecraft

    NASA Astrophysics Data System (ADS)

    Vaverka, Jakub; Mann, Ingrid; Kero, Johan; De Spiegeleer, Alexandre; Hamrin, Maria; Norberg, Carol; Pitkanen, Timo; Pellinen-Wannberg, Asta

    2016-07-01

    There are several methods to measure the cosmic dust entering the Earth's atmosphere such as space-born dust detectors, meteor and HPLA radars, and optical imaging. One complementary method could be to use electric field instruments initially designed to measure electric waves. A plasma cloud generated by a hypervelocity dust impact on a spacecraft body can be detected by the electric field instruments commonly operated on the spacecraft. Since Earth-orbiting missions are generally not equipped with conventional dust detectors, the electric field instruments offer an alternative method to measure the Earth's dust environment. We present the first detection of dust impacts on one of the Earth-orbiting Cluster satellites recorded by the Wide-Band Data (WBD) instrument. We describe the concept of dust impact detection focused on specifics of the Cluster spacecraft and the WBD instrument and their influence on dust impact detection. The detected pulses are compared with theoretical shape based on the model of the recollection of plasma clouds electrons. The estimation of the size and the velocity of the impinging dust grains from the amplitude of the Cluster voltage pulses shown that such impacts can be generated by grains of radius of r = 0.1 μm impacting with the velocity v ˜100 km/s or by grains of radius r = 1 μm impacting with the velocity v ˜10 km/s. We discuss the sensitivity of this method for dust grain detection showing that grains of radius r = 0.01 μm can be detected when impacting with velocity v ˜300 km/s and grains of radius r = 10 μm with velocity v ˜1 km/s if the WBD instrument operates in the high gain level (75 dB).

  16. Hypervelocity impact survivability experiments for carbonaceous impactors, part 2

    SciTech Connect

    Bunch, T.E.; Paque, J.M.; Becker, L.; Vedder, J.F.; Erlichman, J. ||

    1995-02-01

    Hypervelocity impact experiments were performed to further test the survivability of carbonaceous impactors and to determine potential products that may have been synthesized during impact. Diamonds were launched by the Ames two-stage light gas gun into Al plate at velocities of 2.75 and 3.1 km sec(exp -1). FESEM imagery confirms that diamond fragments survived in both experiments. Earlier experiments found that diamonds were destroyed on impact above 4.3 km sec(exp -1). Thus, the upper stability limit for diamond on impact into Al, as determined from our experimental conditions, is between 3.1 and 4.3 km sec(exp -1). Particles of the carbonaceous chondrite Nogoya were also launched into Al at a velocity of 6.2 km sec (exp -1). Laser desorption (L (exp 2) MS) analyses of the impactor residues indicate that the lowest and highest mass polycyclic aromatic hydrocarbons (PAH`s) were largely destroyed on impact; those of intermediate mass (202-220 amu) remained at the same level or increased in abundance. In addition, alkyl-substituted homologs of the most abundant pre-impacted PAH`s were synthesized during impact. These results suggest that an unknown fraction of some organic compounds can survive low to moderate impact velocities and that synthesized products can be expected to form up to velocities of, at least, 6.5 km sec(exp -1). The authors also present examples of craters formed by a unique microparticle accelerator that could launch micron-sized particles of almost any coherent material at velocities up to approximately 15 km sec(exp -1). Many of the experiments have a direct bearing on the interpretation of LDEF craters.

  17. Hypervelocity Impact (HVI). Volume 8; Tile Small Targets A-1, Ag-1, B-1, and Bg-1

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Targets A-1, Ag-1, B-1, and Bg-1 was to study hypervelocity impacts on the reinforced Shuttle Heat Shield Tiles of the Wing. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  18. The Recent Research Progresses in Space Debris Hypervelocity Impact Test in CAST

    NASA Astrophysics Data System (ADS)

    Gong, Zizheng; Dai, Fu; Yang, Jiyun; Hou, Mingqiang; Zheng, Jiandong; Tong, Jingyu; Pang, Hewei

    2009-06-01

    A more perfect projectile/sabot aerodynamic separating technique in hypervelocity impact experiment was developed. By using this technique, the Al sphere with diameters from 10 mm to 1 mm were separated with sabot 100% successfully in the velocity ranges of 3˜ 7km/s, on the two-stage-light-gas gun with 18 mm caliber. The technique of flier-plate with graded wave impedance in hypervelocity launcher was developed, and a titanium plate with 4mm in diameter and 2 mm in thickness was launched to 10km/s. The ballistic limit curve of typical aluminum alloy whipple shield was investigated by both experiment and numerical simulation, the results were compared with Christiansen equation, and a jump phenomena were found at velocity between 8.5km/s and 11km/s in simulation results. The hypervelocity impact damage characteristic and damage model of fused silica glass outer windshield was obtained by using the two-stage-light-gas gun up to 6.5 km/s impacting velocity. The hypervelocity impacts on the outer surfaces functional material, such as the thermal control material, window glass, and OSR etc., by using The Laser-driven Flyer system are also reviewed.

  19. FAR-TECH's Nanoparticle Plasma Jet System and its Application to Disruptions, Deep Fueling, and Diagnostics

    NASA Astrophysics Data System (ADS)

    Thompson, J. R.; Bogatu, I. N.; Galkin, S. A.; Kim, J. S.

    2012-10-01

    Hyper-velocity plasma jets have potential applications in tokamaks for disruption mitigation, deep fueling and diagnostics. Pulsed power based solid-state sources and plasma accelerators offer advantages of rapid response and mass delivery at high velocities. Fast response is critical for some disruption mitigation scenario needs, while high velocity is especially important for penetration into tokamak plasma and its confining magnetic field, as in the case of deep fueling. FAR-TECH is developing the capability of producing large-mass hyper-velocity plasma jets. The prototype solid-state source has produced: 1) >8.4 mg of H2 gas only, and 2) >25 mg of H2 and >180 mg of C60 in a H2/C60 gas mixture. Using a coaxial plasma gun coupled to the source, we have successfully demonstrated the acceleration of composite H/C60 plasma jets, with momentum as high as 0.6 g.km/s, and containing an estimated C60 mass of ˜75 mg. We present the status of FAR-TECH's nanoparticle plasma jet system and discuss its application to disruptions, deep fueling, and diagnostics. A new TiH2/C60 solid-state source capable of generating significantly higher quantities of H2 and C60 in <0.5 ms will be discussed.

  20. Emerging jets

    NASA Astrophysics Data System (ADS)

    Schwaller, Pedro; Stolarski, Daniel; Weiler, Andreas

    2015-05-01

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilities for discovery at LHCb are also discussed.

  1. Survivability of copper projectiles during hypervelocity impacts in porous ice: A laboratory investigation of the survivability of projectiles impacting comets or other bodies

    NASA Astrophysics Data System (ADS)

    McDermott, K. H.; Price, M. C.; Cole, M.; Burchell, M. J.

    2016-04-01

    During hypervelocity impact (>a few km s-1) the resulting cratering and/or disruption of the target body often outweighs interest on the outcome of the projectile material, with the majority of projectiles assumed to be vaporised. However, on Earth, fragments, often metallic, have been recovered from impact sites, meaning that metallic projectile fragments may survive a hypervelocity impact and still exist within the wall, floor and/or ejecta of the impact crater post-impact. The discovery of the remnant impactor composition within the craters of asteroids, planets and comets could provide further information regarding the impact history of a body. Accordingly, we study in the laboratory the survivability of 1 and 2 mm diameter copper projectiles fired onto ice at speeds between 1.00 and 7.05 km s-1. The projectile was recovered intact at speeds up to 1.50 km s-1, with no ductile deformation, but some surface pitting was observed. At 2.39 km s-1, the projectile showed increasing ductile deformation and broke into two parts. Above velocities of 2.60 km s-1 increasing numbers of projectile fragments were identified post impact, with the mean size of the fragments decreasing with increasing impact velocity. The decrease in size also corresponds with an increase in the number of projectile fragments recovered, as with increasing shock pressure the projectile material is more intensely disrupted, producing smaller and more numerous fragments. The damage to the projectile is divided into four classes with increasing speed and shock pressure: (1) minimal damage, (2) ductile deformation, start of break up, (3) increasing fragmentation, and (4) complete fragmentation. The implications of such behaviour is considered for specific examples of impacts of metallic impactors onto Solar System bodies, including LCROSS impacting the Moon, iron meteorites onto Mars and NASA's "Deep Impact" mission where a spacecraft impacted a comet.

  2. A hypervelocity debris simulating technique with laser driven flyer

    NASA Astrophysics Data System (ADS)

    Tong, J.; Dong, H.; Wang, J.

    Theoretical models suggest that most of the space debris in LEO consist of particles are smaller than 0.5mm. LDEF exposed a total surface area of about 130m 2 for 69 months in the LEO environment. It provided a huge collection of impact data that covers a wide size range of impact crater. Total of 34336 impacts were found on the LDEF surface, of which 27385 impact craters were less than 0.5mm in diameter. The small space debris can cause a gradual degradation of a satellite surfaces, including mechanical damage and contamination generated by impacts. Moreover the small debris may cause greater synergistic effects with AO. AO undercutting of impact damage can further expand the damage areas. This paper describes a new method to simulate small space debris by the laser driven flyer technique. A neodymium-glass pulsed laser was used in this work, capable of up 20 joules in 20 nanoseconds. Tow bonding methods to adhere the aluminum foil to the glass substrate were used. One was a field assisted thermal diffusion bond. The other used silicon oil as the adhesive. In the diffusion bond, the laser is used to vaporize the interface of a aluminum foil diffusively bonded to a glass substrate. The vapor reaches high pressures and then cuts out and accelerates a aluminum disk in the diameter of the periphery of the laser beam. In the second flyer configuration, the silicon oil was vaporized by the laser beam and the expanding gas drove the aluminum disc to the hypervelocity. In our tests, both of methods were successful. In the method of silicon oil adhesion, a 2mm diameter, 60micron thick aluminum disc was accelerated to 3.2km/s. But the velocity data of diffusion bond could not be obtained because the meas uring appliance was improper. The method to measure velocity was very simple and cheap. First, the flight time of a particle was measured with a piezoelectric transducer and a digital oscilloscope. Then attaining the flight time and distance of the particle, its velocity

  3. The NASA Ames Hypervelocity Free Flight Aerodynamic Facility: Experimental Simulation of the Atmospheric Break-Up of Meteors

    NASA Technical Reports Server (NTRS)

    Wilder, M. C.; Bogdanoff, D. W.

    2015-01-01

    The Hypervelocity Free Flight Aerodynamic Facility at NASA Ames Research Center provides a potential platform for the experimental simulation of meteor breakup at conditions that closely match full-scale entry condition for select parameters. The poster describes the entry environment simulation capabilities of the Hypervelocity Free Flight Aerodynamic Facility (HFFAF) at NASA Ames Research Center and provides example images of the fragmentation of a hypersonic projectile for which break-up was initiated by mechanical forces (impact with a thin polymer diaphragm).

  4. Synthetic Jets

    NASA Technical Reports Server (NTRS)

    Milanovic, Ivana M.

    2003-01-01

    Current investigation of synthetic jets and synthetic jets in cross-flow examined the effects of orifice geometry and dimensions, momentum-flux ratio, cluster of orifices, pitch and yaw angles as well as streamwise development of the flow field. This comprehensive study provided much needed experimental information related to the various control strategies. The results of the current investigation on isolated and clustered synthetic jets with and without cross-flow will be further analyzed and documented in detail. Presentations at national conferences and publication of peer- reviewed journal articles are also expected. Projected publications will present both the mean and turbulent properties of the flow field, comparisons made with the data available in an open literature, as well as recommendations for the future work.

  5. Impact jetting as the origin of chondrules.

    PubMed

    Johnson, Brandon C; Minton, David A; Melosh, H J; Zuber, Maria T

    2015-01-15

    Chondrules are the millimetre-scale, previously molten, spherules found in most meteorites. Before chondrules formed, large differentiating planetesimals had already accreted. Volatile-rich olivine reveals that chondrules formed in extremely solid-rich environments, more like impact plumes than the solar nebula. The unique chondrules in CB chondrites probably formed in a vapour-melt plume produced by a hypervelocity impact with an impact velocity greater than 10 kilometres per second. An acceptable formation model for the overwhelming majority of chondrules, however, has not been established. Here we report that impacts can produce enough chondrules during the first five million years of planetary accretion to explain their observed abundance. Building on a previous study of impact jetting, we simulate protoplanetary impacts, finding that material is melted and ejected at high speed when the impact velocity exceeds 2.5 kilometres per second. Using a Monte Carlo accretion code, we estimate the location, timing, sizes, and velocities of chondrule-forming impacts. Ejecta size estimates indicate that jetted melt will form millimetre-scale droplets. Our radiative transfer models show that these droplets experience the expected cooling rates of ten to a thousand kelvin per hour. An impact origin for chondrules implies that meteorites are a byproduct of planet formation rather than leftover building material. PMID:25592538

  6. Computational modeling of electrostatic charge and fields produced by hypervelocity impact

    DOE PAGESBeta

    Crawford, David A.

    2015-05-19

    Following prior experimental evidence of electrostatic charge separation, electric and magnetic fields produced by hypervelocity impact, we have developed a model of electrostatic charge separation based on plasma sheath theory and implemented it into the CTH shock physics code. Preliminary assessment of the model shows good qualitative and quantitative agreement between the model and prior experiments at least in the hypervelocity regime for the porous carbonate material tested. The model agrees with the scaling analysis of experimental data performed in the prior work, suggesting that electric charge separation and the resulting electric and magnetic fields can be a substantial effectmore » at larger scales, higher impact velocities, or both.« less

  7. Application of a flux-split algorithm to chemically relaxing, hypervelocity blunt-body flows

    NASA Technical Reports Server (NTRS)

    Balakrishnan, A.

    1987-01-01

    Viscous, nonequilibrium, hypervelocity flow fields over two axisymmetric configurations are numerically simulated using a factored, implicit, flux-split algorithm. The governing gas-dynamic and species-continuity equations for laminar flow are presented. The gas-dynamics/nonequilibrium-chemistry coupling procedure is developed as part of the solution procedure and is described in detail. Numerical solutions are presented for hypervelocity flows over a hemisphere and over an axisymmetric aeroassisted orbital transfer vehicle using three different chemistry models. The gas models considered are those for an ideal gas, for a frozen gas, and for chemically relaxing air consisting of five species. The calculated results are compared with existing numerical solutions in the literature along the stagnation line of the hemisphere. The effects of free-stream Reynolds number on the nonequilibrium flow field are discussed.

  8. Appraisal of UTIAS implosion-driven hypervelocity launchers and shock tubes.

    NASA Technical Reports Server (NTRS)

    Glass, I. I.

    1972-01-01

    A critical appraisal is made of the design, research, development, and operation of the novel UTIAS implosion-driven hypervelocity launchers and shock tubes. Explosively driven (PbN6-lead azide, PETN-pentaerythritetetranitrate) implosions in detonating stoichiometric hydrogen-oxygen mixtures have been successfully developed as drivers for hypervelocity launchers and shock tubes in a safe and reusable facility. Intense loadings at very high calculated pressures, densities, and temperatures, at the implosion center, cause severe problems with projectile integrity. Misalignment of the focal point can occur and add to the difficulty in using small caliber projectiles. In addition, the extreme driving conditions cause barrel expansion, erosion, and possible gas leakage from the base to the head of the projectile which cut the predicted muzzle velocities to half or a third of the lossless calculated values. However, in the case of a shock-tube operation these difficulties are minimized or eliminated and the possibilities of approaching Jovian reentry velocities are encouraging.

  9. Conceptual Design of a Hypervelocity Asteroid Intercept Vehicle (HAIV) Flight Validation Mission

    NASA Technical Reports Server (NTRS)

    Barbee, Brent W.; Wie, Bong; Steiner, Mark; Getzandanner, Kenneth

    2013-01-01

    In this paper we present a detailed overview of the MDL study results and subsequent advances in the design of GNC algorithms for accurate terminal guidance during hypervelocity NEO intercept. The MDL study produced a conceptual con guration of the two-body HAIV and its subsystems; a mission scenario and trajectory design for a notional flight validation mission to a selected candidate target NEO; GNC results regarding the ability of the HAIV to reliably intercept small (50 m) NEOs at hypervelocity (typically greater than 10 km/s); candidate launch vehicle selection; a notional operations concept and cost estimate for the flight validation mission; and a list of topics to address during the remainder of our NIAC Phase II study.

  10. Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas

    SciTech Connect

    Close, Sigrid; Lee, Nicolas; Johnson, Theresa; Goel, Ashish; Fletcher, Alexander; Linscott, Ivan; Strauss, David; Lauben, David; Srama, Ralf; Mocker, Anna; Bugiel, Sebastian

    2013-09-15

    Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (∼10{sup 28} m{sup −3}), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

  11. A modular high precision digital system for hypervelocity projectile performance measurements

    NASA Astrophysics Data System (ADS)

    Nagarkar, Vivek V.; Singh, Bipin; Miller, Stuart; Campbell, Larry; Bishel, Ron; Rushing, Rick

    2008-04-01

    The performance measurement of hypervelocity projectiles in flight is critical in ensuring proper projectile operation, for designing new long-range missile systems with improved accuracy, and for assessing damage to the target upon impact to determine the projectile's lethality. We are developing a modular, low cost, digital X-ray imaging system to measure hypervelocity projectile parameters with high precision and to almost instantaneously map its trajectory in 3D space to compute its pitch, yaw, displacement from its path, and velocity. The preliminary data suggest that this system can render an accuracy of 0.25° in measuring pitch and yaw, an accuracy of 0.03" in estimating displacement from the centerline, and a precision of +/-0.0001% in measuring velocity, which is well beyond the capability of any existing system.

  12. Hypervelocity impact on brittle materials of semi-infinite thickness: fracture morphology related to projectile diameter

    NASA Astrophysics Data System (ADS)

    Taylor, Emma A.; Kay, Laurie; Shrine, Nick R. G.

    Hypervelocity impact on brittle materials produces features not observed on ductile targets. Low fracture toughness and high yield strength produce a range of fracture morphologies including cracking, spallation and shatter. For sub-mm diameter projectiles, impact features are characterised by petaloid spallation separated by radial cracks. The conchoidal or spallation diameter is a parameter in current cratering equations. An alternative method for interpreting hypervelocity impacts on glass targets of semi-infinite thickness is tested against impact data produced using the Light Gas Gun (LGG) facility at the University of Kent at Canterbury (UKC), U.K. Spherical projectiles of glass and other materials with diameters 30-300 μm were fired at ~5 km s^-1 at a glass target of semi-infinite thickness. The data is used to test a power law relationship between projectile diameter and crack length. The results of this work are compared with published cratering/spallation equations for brittle materials.

  13. Response of Organic Materials to Hypervelocity Impacts (up to 11.2 km/sec)

    NASA Astrophysics Data System (ADS)

    Bass, D. S.; Murphy, W. M.; Miller, G. P.; Grosch, D. J.; Walker, J. D.; Mullin, A.; Waite, J. H.

    1998-09-01

    It is speculated that organic-rich planetesimals played a role in the origin of life on Earth. However, the mechanism by which organics could have been delivered from space to a planetary surface is difficult to determine. Particularly problematic is the question of the stability of organic material under hypervelocity impact conditions. Although some evidence suggests organic molecules cannot survive impacts from projectile velocities greater than about 10 km/sec [1], other investigators have found that impacts create a favorable environment for post-shock recombination of organic molecules in the plume phase [2, 3]. Understanding the mechanisms involved in delivering organics to a planetary surface remains difficult to assess due to the lack of experimental results of hypervelocity impacts, particularly in the velocity range of tens of km/sec. Organic material preservation and destruction from impact shocks, the synthesis of organics in the post-impact plume environment, and implications of these processes for Earth and Mars can be investigated by launching an inorganic projectile into an analog planetesimal-and-bolide organic-rich target. We explored the pressure and temperature ranges of hypervelocity impacts (11.2 km/sec) through simulations with CTH impact physics computer code. Using an inhibited shaped-charge launcher, we also experimentally determined the response of organic material to hypervelocity impacts. Initial work focused on saturating well-characterized zeolitic tuff with an aqueous solution containing dissolved naphthalene, a common polycyclic aromatic hydrocarbon (PAH). Porosity measurements, thin section, and x-ray diffraction analyses were performed to determine that the tuff is primarily fine-grained clinoptilolite. In order to distinguish between contaminants and compounds generated or destroyed in the impact, we tagged the aqueous component of our target with deuterium. Experimental tests revealed that to first order, naphthalene survived

  14. A model for debris clouds produced by impact of hypervelocity projectiles on multiplate structures

    NASA Astrophysics Data System (ADS)

    Zhang, Qingming; Long, Renrong; Huang, Fenglei; Chen, Li; Fu, Yuesheng

    2008-11-01

    Hypervelocity impact of spherical and cylindrical projectiles on multipate shields at velocities between 4 and 6km/s was investigated experimentally. A model was developed to describe the motion of the debris clouds generated. Good agreement was obtained between the experimental and simulation results. The model is capable of predicting damage induced by the impact and can be applied to the optimization and design of multiplate shields.

  15. Testing and numerical modeling of hypervelocity impact damaged Space Station multilayer insulation

    NASA Technical Reports Server (NTRS)

    Rule, William K.

    1992-01-01

    Results are presented of experiments measuring the degradation of the insulating capabilities of the multilayer insulation (MLI) of the Space Station Freedom, when subjected to hypervelocity impact damage. A simple numerical model was developed for use in an engineering design environment for quick assessment of thermal effect of the impact. The model was validated using results from thermal vacuum tests on MLI with simulated damage. The numerical model results agreed with experimental data.

  16. Experimental demonstration of plasma-drag acceleration of a dust cloud to hypervelocities.

    PubMed

    Ticoş, C M; Wang, Zhehui; Wurden, G A; Kline, J L; Montgomery, D S; Dorf, L A; Shukla, P K

    2008-04-18

    Simultaneous acceleration of hundreds of dust particles to hypervelocities by collimated plasma flows ejected from a coaxial gun is demonstrated. Graphite and diamond grains with radii between 5 and 30 microm, and flying at speeds up to 3.7 km/s, have been recorded with a high-speed camera. The observations agree well with a model for plasma-drag acceleration of microparticles much larger than the plasma screening length. PMID:18518115

  17. Ink-jet fabrication of electronic components

    NASA Astrophysics Data System (ADS)

    Bidoki, S. M.; Lewis, D. M.; Clark, M.; Vakorov, A.; Millner, P. A.; McGorman, D.

    2007-05-01

    Nanosized metallic particles dispersed in a polymeric matrix have been used conventionally as a paste or ink to print electrically active patterns on different substrates. The potential of ink-jet printing in this field is clearly important but the challenge to date has been how to achieve prints of low volume resistivity from the very low viscosity ink required for ink-jet printing. In this study, ink-jet printing techniques were used to directly deposit metallic conductive patterns to produce wiring boards, antennas, electrodes and so forth. In these methods, aqueous solutions of metal salt and reducing agent were ink-jet printed consecutively onto the substrate, where an immediate chemical reduction transformed the metal cations into very fine metallic particles. The best performing reducing agent for ink-jet metal deposition was found to be ascorbic acid at neutral pH. Using this chemistry, nanosized silver patterns, composed of particles in the size range 10-200 nm, were successfully formed using a standard office ink-jet thermal-head printer. Deposited layers of silver with high electrical conductance up to 1.89 × 105 S m-1 and sheet resistance up to 0.5 Ω/squ were printed whilst higher conductivities might be expected using more appropriate devices.

  18. Damage Characteristics of the Logical Chip Module Due to Plasma Created by Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Tang, Enling; Wu, Jin; Wang, Meng; Zhang, Lijiao; Xiang, Shenghai; Xia, Jin; Liu, Shuhua; He, Liping; Han, Yafei; Xu, Mingyang; Zhang, Shuang; Yuan, Jianfei

    2016-04-01

    To researching the damage characteristics of typical logical chip modules in spacecraft due to plasma generated by hypervelocity impacts, we have established a triple Langmuir probe diagnostic system and a logical chips measurement system, which were used to diagnose plasma characteristic parameters and the logical chip module's logical state changes due to the plasma created by a 7075 aluminum projectile hypervelocity impact on the 2A12 aluminum target. Three sets of experiments were performed with the collision speeds of 2.85 km/s, 3.1 km/s and 2.20 km/s, at the same incident angles of 30 degrees and logical chip module's positions by using a two-stage light gas gun loading system, a plasma characteristic parameters diagnostic system and a logical chip module's logical state measurement system, respectively. Electron temperature and density were measured at given position and azimuth, and damage estimation was performed for the logical chip module by using the data acquisition system. Experimental results showed that temporary damage could be induced on logical chip modules in spacecraft by plasma generated by hypervelocity impacts under the given experimental conditions and the sensors' position and azimuth. supported by National Natural Science Foundation of China (Nos. 10972145, 11272218, 11472178), Program for Liaoning Excellent Talents in University of China (No. LR2013008), Open Foundation of Key Laboratory of Liaoning Weapon Science and Technology, Liaoning Province Talents Engineering Projects of China (No. 2012921044)

  19. The Laser-driven Flyer System for Space Debris Hypervelocity Impact Simulations

    NASA Astrophysics Data System (ADS)

    Gong, Zizheng; Dai, Fu; Yang, Jiyun; Hou, Mingqiang; Zheng, Jiandong; Tong, Jingyu; Pang, Hewei

    2009-06-01

    The Laser-driven flyer (LDF) technique is showing promiseful in simulating micro meteoroids and orbital debris (M/OD) hypervelocity impacting effects. LDF system with a single pulses from a Q-switched Nd: glass laser, of 15 ns duration and up to 20J energy, launched the aluminum films of 5 μm thickness up to 8.3km/s velocity was developed in Beijing Institute of Spacecrafts Environment Engineering(BISEE), CAST. The quantitative relationships between the flyer velocity and the laser energy, the width of laser pulse, the diameter of laser focal spot, and the flyer thickness were analyzed, according to Lawrence-Gurney model, and compared with the experimental results. Some experimental aspects in our efforts on the space debris Hypervelocity impacts on the outer surfaces functional material, such as the thermal control material, window glass, and OSR etc., are reviewed. Though still developing, the Laser-driven flyer technique has been demonstrated promise in simulating micro M/OD hypervelocity impacting effects.

  20. Dust generation at interaction of plasma jet with surfaces

    NASA Astrophysics Data System (ADS)

    Ticos, Catalin; Toader, Dorina; Banu, Nicoleta; Scurtu, Adrian; Oane, Mihai

    2013-10-01

    Coatings of W and C with widths of a few microns will be exposed to plasma jet for studying the erosion of the surface and detachment of micron size dust particles. A coaxial plasma gun has been built inside a vacuum chamber for producing supersonic plasma jets. Its design is based on a 50 kJ coaxial plasma gun which has been successfully used for accelerating hypervelocity dust. Initial shots were carried out for a capacitor bank with C = 12 μF and charged up to 2 kV. Currents of tens of amps were measured with a Rogowsky coil and plasma flow speeds of 4 km/s were inferred from high-speed images of jet propagation. An upgrade consisting in adding capacitors in parallel will be performed in order to increase the energy up to 2 kJ. A coil will be installed at the gun muzzle to compress the plasma flow and increase the energy density of the jet on the sample surface. A CCD camera with a maximum recording speed of 100 k fps and a maximum resolution of 1024 × 1024 pixels was set for image acquisition of the plasma and dust. A laser system used to illuminate the ejected dust from the surface includes a laser diode emitting at 650 nm with a beam power of 25 mW. The authors acknowledge support from EURATOM WP13-IPH-A03-P2-02-BS22.

  1. Metallization and insulization during impact

    SciTech Connect

    Gilman, J.J.

    1992-10-01

    It is pointed out that the large strains produced by hypervelocity impacts can be expected to produce dramatic changes in the chemical bonding (electronic structures) of materials. This will change the mechanical behavior towards increased ductility when a semiconductor is compressed until it becomes metallic; and towards increased brittleness when a transition metal is expanded so as to localize its d-band electrons. Both isotropic compression (expansion) and shear strains can cause these transformations. Critical deformation criteria are given based on the observed cubic to tetragonal transformations in compressed semiconductors.

  2. Jets in air-jet family

    NASA Technical Reports Server (NTRS)

    Navia, C. E.; Sawayanagi, K.

    1985-01-01

    The A-jet families on Chacaltaya emulsion chamber experiments were analyzed by the study of jets which are reconstructed by a grouping procedure. It is demonstrated that large-E sub J R sub J events are characterized by small number of jets and two-jet like asymmetric shape, binocular events and the other type. This type has a larger number of jets and more symmetrical shape in the P sub t plane.

  3. Marine Jet

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The marine turbine pump pictured is the Jacuzzi 12YJ, a jet propulsion system for pleasure or commercial boating. Its development was aided by a NASA computer program made available by the Computer Software Management and Information Center (COSMIC) at the University of Georgia. The manufacturer, Jacuzzi Brothers, Incorporated, Little Rock, Arkansas, used COSMIC'S Computer Program for Predicting Turbopump Inducer Loading, which enabled substantial savings in development time and money through reduction of repetitive testing.

  4. CQ-4: a 4 MA, 500ns Compact Pulsed Power Generator Dedicated to Magnetically Driven Quasi-isentropic Compression Experiments (ICE) and Hypervelocity Flyer Plates

    NASA Astrophysics Data System (ADS)

    Wang, Guiji; Zhao, Jianheng; Sun, Chengwei; Kuai, Bin; Mo, Jianjun; Wu, Gang

    2011-06-01

    Compact pulsed power generators have been widely used to produce high magnetic pressure to study dynamic behaviors of materials and do some hypervelocity impact experiments. After the compact pulsed power generator CQ-1.5 developed by us, a larger current and shorter rise time compact pulsed power generator CQ-4 has been designed and being constructed. The generator CQ-4 is composed of 20 energy-storage modules in parallel, of which is constituted by a 1.6 μF, 100 kV capacitor and a coaxial field-distortion spark gas switch with inductance of 25 nH. The energy is transmitted by the aluminum strip transmission lines insulated by 16 layers of Mylar films, of which is 0.1 mm in thickness. Before the short-circuit load, 72 peaking capacitors in parallel with the energy-storage capacitors are used to shape the discharging current waveforms in load. Each peaking capacitor is with rated capacitance of 0.1 μF and rated voltage of 120 kV. When the capacitor is charged to 70-80 kV, the peak current can reach 4-5MA, and the rise time is 400-500 ns (0-100%). The expected magnetic pressure can be up to 100GPa on the metallic loads and a hypervelocity of 12-15 km/s can be reached for the aluminum flyer plates with size of 10 mm in diameter and 1.0 mm in thickness.

  5. DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

    SciTech Connect

    Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.; Falconer, David A.

    2010-09-01

    By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

  6. Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets

    NASA Technical Reports Server (NTRS)

    Moore, R. L.; Cirtain, J. W.; Sterling, A. C.; Falconer, D. A.

    2010-01-01

    By examining many X-ray jets in Hinode/XRT coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H alpha macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major CMEs. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 Angstrom snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T 10(exp 4) - 10(exp 5) K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

  7. Methodology of design and analysis of external walls of space station for hypervelocity impacts by meteoroids and space debris

    NASA Technical Reports Server (NTRS)

    Batla, F. A.

    1986-01-01

    The development of criteria and methodology for the design and analysis of Space Station wall elements for collisions with meteoroids and space debris at hypervelocities is discussed. These collisions will occur at velocities of 10 km/s or more and can be damaging to the external wall elements of the Space Station. The wall elements need to be designed to protect the pressurized modules of the Space Station from functional or structural failure due to these collisions at hypervelocities for a given environment and population of meteoroids and space debris. The design and analysis approach and the associated computer program presented is to achieve this objective, including the optimization of the design for a required overall probability of no penetration. The approach is based on the presently available experimental and actual data on meteoroids and space debris flux and damage assessments and the empirical relationships resulting from the hypervelocity impact studies in laboratories.

  8. Hypervelocity Impacts on ISS Handrails and Evaluation of Alternative Materials to Prevent Extravehicular Mobility Unit (EMU) Glove Damage During EVA

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon; Christiansen, Eruc; Davis, B. Alan; Ordonez, Erick

    2009-01-01

    During post-flight processing of STS-116, damage to crewmember Robert Curbeam's Phase VI Glove Thermal Micrometeoroid Garment was discovered. This damage consisted of: loss of RTV-157 palm pads on the thumb area on the right glove, a 0.75 inch cut in the Vectran adjacent to the seam and thumb pad (single event cut), constituting the worst glove damage ever recorded for the U.S. space program. The underlying bladder and restraint were found not be damaged by this event. Evaluation of glove damage found that the outer Vectran fibers were sliced as a result of contact with a sharp edge or pinch point rather than general wear or abrasion (commonly observed on the RTV pads). Damage to gloves was also noted on STS-118 and STS-120. One potential source of EMU glove damages are sharp crater lips on external handrails, generated by micrometeoroid and orbital debris (MMOD) impacts. In this paper, the results of a hypervelocity impact (HVI) test program on representative and actual ISS handrails are presented. These tests were performed in order to characterize impact damage profiles on ISS handrails and evaluate alternatives for limiting risk to future missions. It was determined that both penetrating and non-penetrating MMOD impacts on aluminum and steel ISS handrails are capable of generating protruding crater profiles which exceed the heights required for EMU glove abrasion risk by an order of magnitude. Testing demonstrated that flexible overwraps attached to the outside of existing handrails are capable of limiting contact between hazardous crater formations and crewmember gloves during extravehicular activity (EVA). Additionally, replacing metallic handrails with high strength, low ductility, fiber reinforced composite materials would limit the formation of protruding crater lips on new ISS modules.

  9. Endoscopic extra-cavitary drainage of pancreatic necrosis with fully covered self-expanding metal stents (fcSEMS) and staged lavage with a high-flow water jet system

    PubMed Central

    Smith, Ioana B.; Gutierrez, Juan P.; Ramesh, Jayapal; Wilcox, C. Mel; Mönkemüller, Klaus E.

    2015-01-01

    Aim: To present a novel, less-invasive method of endoscopic drainage (ED) for walled-off pancreatic necrosis (WON).We describe the feasibility, success rate, and complications of combined ED extra-cavitary lavage and debridement of WON using a biliary catheter and high-flow water jet system (water pump). Patients and methods: Endoscopic ultrasound (EUS)-guided drainage was performed with insertion of two 7-Fr, 4-cm double pigtail stents. Subsequently a fully covered self-expanding metal stent (fcSEMS) was placed. The key aspect of the debridement was the insertion of a 5-Fr biliary catheter through or along the fcSEMS into the cavity, with ensuing saline lavage using a high-flow water jet system. The patients were then brought back for repeated, planned endoscopic lavages of the WON. No endoscopic intra-cavitary exploration was performed. Results: A total of 17 patients (15 men, 2 women; mean age 52.6, range 24 – 69; mean American Society of Anesthesiologists [ASA] score of 3) underwent ED of WON with this new method. The mean initial WON diameter was 9.5 cm, range 8 to 26 cm. The total number of ED was 84, range 2 to 13. The mean stenting period was 42.5 days. The mean follow-up was 51 days, range 3 to 370. A resolution of the WON was achieved in 14 patients (82.3 %). There were no major complications associated with this method. Conclusion: ED of complex WON with fcSEMS followed by repeated endoscopic extra-cavitary lavage and debridement using a biliary catheter and high-flow water jet system is a minimally invasive, feasible method with high technical and clinical success and minimal complications. PMID:26135660

  10. Plasma jet ignition device

    DOEpatents

    McIlwain, Michael E.; Grant, Jonathan F.; Golenko, Zsolt; Wittstein, Alan D.

    1985-01-15

    An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

  11. Inclusive Jets in PHP

    NASA Astrophysics Data System (ADS)

    Roloff, P.

    Differential inclusive-jet cross sections have been measured in photoproduction for boson virtualities Q^2 < 1 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 300 pb^-1. Jets were identified in the laboratory frame using the k_T, anti-k_T or SIScone jet algorithms. Cross sections are presented as functions of the jet pseudorapidity, eta(jet), and the jet transverse energy, E_T(jet). Next-to-leading-order QCD calculations give a good description of the measurements, except for jets with low E_T(jet) and high eta(jet). The cross sections have the potential to improve the determination of the PDFs in future QCD fits. Values of alpha_s(M_Z) have been extracted from the measurements based on different jet algorithms. In addition, the energy-scale dependence of the strong coupling was determined.

  12. Experimental static aerodynamics of a regular hexagonal prism in a low density hypervelocity flow

    NASA Technical Reports Server (NTRS)

    Guy, R. W.; Mueller, J. N.; Lee, L. P.

    1972-01-01

    A regular hexagonal prism, having a fineness ratio of 1.67, has been tested in a wind tunnel to determine its static aerodynamic characteristics in a low-density hypervelocity flow. The prism tested was a 1/4-scale model of the graphite heat shield which houses the radioactive fuel for the Viking spacecraft auxiliary power supply. The basic hexagonal prism was also modified to simulate a prism on which ablation of one of the six side flats had occurred. This modified hexagonal prism was tested to determine the effects on the aerodynamic characteristics of a shape change caused by ablation during a possible side-on stable reentry.

  13. Measurement of incident position of hypervelocity particles on piezoelectric lead zirconate titanate detector

    SciTech Connect

    Takechi, Seiji; Onishi, Toshiyuki; Minami, Shigeyuki; Miyachi, Takashi; Fujii, Masayuki; Hasebe, Nobuyuki; Nogami, Ken-ichi; Ohashi, Hideo; Sasaki, Sho; Shibata, Hiromi; Iwai, Takeo; Gruen, Eberhard; Srama, Ralf; Okada, Nagaya

    2008-04-15

    A cosmic dust detector for use onboard a satellite is currently being developed by using piezoelectric lead zirconate titanate (PZT). The characteristics of the PZT detector have been studied by bombarding it with hypervelocity iron (Fe) particles supplied by a Van de Graaff accelerator. One central electrode and four peripheral electrodes were placed on the front surface of the PZT detector to measure the impact positions of the incident Fe particles. It was demonstrated that the point of impact on the PZT detector could be identified by using information on the time at which the first peak of the output signal obtained from each electrode appeared.

  14. Spontaneous magnetic field generation in hypervelocity impacts. [of meteoroids onto lunar and planetary surfaces

    NASA Technical Reports Server (NTRS)

    Srnka, L. J.

    1977-01-01

    Hypervelocity impacts of meteoroids onto early planetary surfaces may have generated short-lived magnetic fields. The high specific power densities of the impacts, plasma production in the ejecta clouds, and the chemically layered targets of the meteoroids are analyzed in describing the evolution of the magnetic fields. Durations from about one millionth of a minute to one minute, as well as strengths up to 100 tesla, are posited for the impact-generated magnetic fields. The analogy of magnetic-field generation in laser-target experiments is also mentioned. The acquisition of shock remanence and thermoremanence by the ejecta and nearby rock following impact is discussed.

  15. Classical molecular dynamics simulations of hypervelocity nanoparticle impacts on amorphous silica

    SciTech Connect

    Samela, Juha; Nordlund, Kai

    2010-02-01

    We have investigated the transition from the atomistic to the macroscopic impact mechanism by simulating large Argon cluster impacts on amorphous silica. The transition occurs at cluster sizes less than 50 000 atoms at hypervelocity regime (22 km/s). After that, the crater volume increases linearly with the cluster size opposite to the nonlinear scaling typical of small cluster impacts. The simulations demonstrate that the molecular dynamics method can be used to explore atomistic mechanisms that lead to damage formation in small particle impacts, for example, in impacts of micrometeorites on spacecraft.

  16. Study of Forebody Injection and Mixing with Application to Hypervelocity Airbreathing Propulsion

    NASA Technical Reports Server (NTRS)

    Axdahl, Erik; Kumar, Ajay; Wilhite, Alan

    2012-01-01

    The use of premixed, shock-induced combustion in the context of a hypervelocity, airbreathing vehicle requires effective injection and mixing of hydrogen fuel and air on the vehicle forebody. Three dimensional computational simulations of fuel injection and mixing from flush-wall and modified ramp and strut injectors are reported in this study. A well-established code, VULCAN, is used to conduct nonreacting, viscous, turbulent simulations on a flat plate at conditions relevant to a Mach 12 flight vehicle forebody. In comparing results of various fuel injection strategies, it is found that strut injection provides the greatest balance of performance between mixing efficiency and stream thrust potential.

  17. Hypervelocity dust impact craters on photovoltaic devices imaged by ion beam induced charge

    NASA Astrophysics Data System (ADS)

    Yang, Changyi; Wu, Yiyong; Lv, Gang; Rubanov, Sergey; Jamieson, David N.

    2015-04-01

    Hypervelocity dust has a speed of greater than 5 km/s and is a significant problem for equipment deployed in space such as satellites because of impacts that damage vulnerable components. Photovoltaic (PV) arrays are especially vulnerable because of their large surface area and the performance can be degraded owing to the disruption of the structure of the junction in the cells making up the array. Satellite PV arrays returned to Earth after service in orbit reveal a large number of craters larger than 5 μm in diameter arising from hypervelocity dust impacts. Extensive prior work has been done on the analysis of the morphology of craters in PV cells to understand the origin of the micrometeoroid that caused the crater and to study the corresponding mechanical damage to the structure of the cell. Generally, about half the craters arise from natural micrometeoroids, about one third from artificial Al-rich debris, probably from solid rocket exhausts, and the remainder from miscellaneous sources both known and unknown. However to date there has not been a microscopic study of the degradation of the electrical characteristics of PV cells exposed to hypervelocity dust impacts. Here we present an ion beam induced charge (IBIC) pilot study by a 2 MeV He microbeam of craters induced on a Hamamatsu PIN diode exposed to artificial hypervelocity Al dust from a dust accelerator. Numerous 5-30 μm diameter craters were identified and the charge collection efficiency of the crater and surrounds mapped with IBIC with bias voltages between 0 and 20 V. At highest bias, it was found the efficiency of the crater had been degraded by about 20% compared to the surrounding material. The speed distribution achieved in the Al dust accelerator was peaked at about 4 km/s compared to 11-68 km/s for dust encountered in low Earth orbit. We are able to extrapolate the charge collection efficiency degradation rate of unbiased cells in space based on our current measurements and the differences

  18. Classical molecular dynamics simulations of hypervelocity nanoparticle impacts on amorphous silica

    NASA Astrophysics Data System (ADS)

    Samela, Juha; Nordlund, Kai

    2010-02-01

    We have investigated the transition from the atomistic to the macroscopic impact mechanism by simulating large Argon cluster impacts on amorphous silica. The transition occurs at cluster sizes less than 50000 atoms at hypervelocity regime (22 km/s). After that, the crater volume increases linearly with the cluster size opposite to the nonlinear scaling typical of small cluster impacts. The simulations demonstrate that the molecular dynamics method can be used to explore atomistic mechanisms that lead to damage formation in small particle impacts, for example, in impacts of micrometeorites on spacecraft.

  19. Microfractures produced by a laboratory scale hypervelocity impact into granite. [for lunar sample crack spectra interpretation

    NASA Technical Reports Server (NTRS)

    Siegfried, R. W., II; Simmons, G.; Richter, D.; Hoerz, F.

    1977-01-01

    Differential strain analysis and scanning electron microscopy are employed to study the microcracks produced in a granite block by shock waves from a hypervelocity impact. The anisotropy of the pre-shock cracks appears to control the orientations of the microcracks. Over the range 2 to 20 kbar, total crack porosity proves to be linearly related to shock pressure. The effect of the peak shock pressure on the width and median closure pressure of the crack spectra is also investigated. The results of the microcrack study may be useful in interpreting lunar samples.

  20. An Ellipsoidal Particle-Finite Element Method for Hypervelocity Impact Simulation. Chapter 1

    NASA Technical Reports Server (NTRS)

    Shivarama, Ravishankar; Fahrenthold, Eric P.

    2004-01-01

    A number of coupled particle-element and hybrid particle-element methods have been developed for the simulation of hypervelocity impact problems, to avoid certain disadvantages associated with the use of pure continuum based or pure particle based methods. To date these methods have employed spherical particles. In recent work a hybrid formulation has been extended to the ellipsoidal particle case. A model formulation approach based on Lagrange's equations, with particles entropies serving as generalized coordinates, avoids the angular momentum conservation problems which have been reported with ellipsoidal smooth particle hydrodynamics models.

  1. Thermal protection for hypervelocity flight in earth's atmosphere by use of radiation backscattering ablating materials

    NASA Technical Reports Server (NTRS)

    Howe, John T.; Yang, Lily

    1991-01-01

    A heat-shield-material response code predicting the transient performance of a material subject to the combined convective and radiative heating associated with the hypervelocity flight is developed. The code is dynamically interactive to the heating from a transient flow field, including the effects of material ablation on flow field behavior. It accomodates finite time variable material thickness, internal material phase change, wavelength-dependent radiative properties, and temperature-dependent thermal, physical, and radiative properties. The equations of radiative transfer are solved with the material and are coupled to the transfer energy equation containing the radiative flux divergence in addition to the usual energy terms.

  2. Predicting multi-wall structural response to hypervelocity impact using the hull code

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1993-01-01

    Previously, multi-wall structures have been analyzed extensively, primarily through experiment, as a means of increasing the meteoroid/space debris impact protection of spacecraft. As structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative to experimental testing, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under different impact loading conditions. The results of comparing experimental tests to Hull Hydrodynamic Computer Code predictions are reported. Also, the results of a numerical parametric study of multi-wall structural response to hypervelocity cylindrical projectile impact are presented.

  3. A Kernel-Free Particle-Finite Element Method for Hypervelocity Impact Simulation. Chapter 4

    NASA Technical Reports Server (NTRS)

    Park, Young-Keun; Fahrenthold, Eric P.

    2004-01-01

    An improved hybrid particle-finite element method has been developed for the simulation of hypervelocity impact problems. Unlike alternative methods, the revised formulation computes the density without reference to any kernel or interpolation functions, for either the density or the rate of dilatation. This simplifies the state space model and leads to a significant reduction in computational cost. The improved method introduces internal energy variables as generalized coordinates in a new formulation of the thermomechanical Lagrange equations. Example problems show good agreement with exact solutions in one dimension and good agreement with experimental data in a three dimensional simulation.

  4. Impact jetting of geological materials.

    NASA Astrophysics Data System (ADS)

    Yang, Wenbo; Ahrens, Thomas J.

    1995-08-01

    To understand jetting of earth materials, gabbro slabs (5 mm thick) were accelerated to 1.5-2 km sec -1 and impacted gabbro (5-10 mm thick), novaculite (10 mm thick), and porous sandstone (12 mm thick) targets at inclination angles of 30°-60°. The ejecta were collected using a catcher box filled with styrofoam and the particles are extracted using chloroform. Jetting angles are determined by the relative positions of the target and the crater produced by the ejecta. The mass of the ejected particles per unit area (˜50 mg cm -2) of the impactor remains almost independent of the impact velocity, inclination angle, thickness of the target and sample mineralogy, and density. Hydrodynamic models are used to calculate the jetting mass, angle, and velocity. Theoretical models predict ˜6 times more ejecta than the experimentally measured as the inclination angle increases. X-ray diffraction of the recovered ejecta shows that it is still in crystalline form, which agrees with thermodynamic calculations. Because the experimental results indicate that the theoretical jetting model for thin metal plates provides a poor description of the experiments, the application of metal plate theory to planet-sized objects appears to be questionable.

  5. Corporate Jet

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Gulfstream Aerospace Corporation, Savannah, GA, used a version of a NASA program called WIBCO to design a wing for the Gulfstream IV (G-IV) which will help to reduce transonic drag (created by shock waves that develop as an airplane approaches the speed of sound). The G-IV cruises at 88 percent of the speed of sound, and holds the international record in its class for round-the-world flight. They also used the STANS5 and Profile programs in the design. They will use the NASA program GASP to help determine the gross weight, range, speed, payload and optimum wing area of an intercontinental supersonic business jet being developed in cooperation with Sukhoi Design Bureau, a Soviet organization.

  6. Focused Ion Beam Recovery of Hypervelocity Impact Residue in Experimental Craters on Metallic Foils.

    SciTech Connect

    Graham, G A; Teslich, N; Dai, Z R; Bradley, J P; Kearsley, A T; Horz, F

    2005-11-04

    The Stardust sample return capsule will return to Earth in January 2006 with primitive debris collected from Comet 81P/Wild-2 during the fly-by encounter in 2004. In addition to the cometary particles embedded in low-density silica aerogel, there will be microcraters preserved in the Al foils (1100 series; 100 {micro}m thick) that are wrapped around the sample tray assembly. Soda lime spheres ({approx}49 {micro}m in diameter) have been accelerated with a Light Gas Gun into flight-grade Al foils at 6.35 km s{sup -1} to simulate the capture of cometary debris. The experimental craters have been analyzed using scanning electron microscopy (SEM) and x-ray energy dispersive spectroscopy (EDX) to locate and characterize remnants of the projectile material remaining within the craters. In addition, ion beam induced secondary electron imaging has proven particularly useful in identifying areas within the craters that contain residue material. Finally, high-precision focused ion beam (FIB) milling has been used to isolate and then extract an individual melt residue droplet from the interior wall of an impact. This enabled further detailed elemental characterization, free from the background contamination of the Al foil substrate. The ability to recover ''pure'' melt residues using FIB will significantly extend the interpretations of the residue chemistry preserved in the Al foils returned by Stardust.

  7. Focused Ion Beam Recovery of Hypervelocity Impact Residue in Experimental Craters on Metallic Foils

    NASA Technical Reports Server (NTRS)

    Graham, G. A.; Teslich, N.; Dai, Z. R.; Bradley, J. P.; Kearsley, A. T.; Horz, F.

    2006-01-01

    The Stardust sample return capsule will return to Earth in January 2006 with primitive debris collected from Comet 81P/Wild-2 during the fly-by encounter in 2004. In addition to the cometary particles embedded in low-density silica aerogel, there will be microcraters preserved in the Al foils (1100 series; 100 micrometers thick) that are wrapped around the sample tray assembly. Soda lime spheres (approximately 49 m in diameter) have been accelerated with a light-gas-gun into flight-grade Al foils at 6.35 km s(sup -1) to simulate the potential capture of cometary debris. The preserved crater penetrations have been analyzed using scanning electron microscopy (SEM) and x-ray energy dispersive spectroscopy (EDX) to locate and characterize remnants of the projectile material remaining within the craters. In addition, ion beam induced secondary electron imaging has proven particularly useful in identifying areas within the craters that contain residue material. Finally, high-precision focused ion beam (FIB) milling has been used to isolate and then extract an individual melt residue droplet from the interior wall of an impact penetration. This enabled further detailed elemental characterization, free from the background contamination of the Al foil substrate. The ability to recover pure melt residues using FIB will significantly extend the interpretations of the residue chemistry preserved in the Al foils returned by Stardust.

  8. Jet inclusive cross sections

    SciTech Connect

    Del Duca, V.

    1992-11-01

    Minijet production in jet inclusive cross sections at hadron colliders, with large rapidity intervals between the tagged jets, is evaluated by using the BFKL pomeron. We describe the jet inclusive cross section for an arbitrary number of tagged jets, and show that it behaves like a system of coupled pomerons.

  9. Supersonic gas jets

    NASA Astrophysics Data System (ADS)

    Dulov, V. G.

    The papers presented in this volume provide an overview of the current state of research in the gas dynamics of jet flows. In particular, attention is given to free supersonic jets and to the interaction of supersonic jets with one another and with obstacles under stationary and nonstationary flow conditions. Papers are presented on a method for calculating a weakly anisotropic supersonic turbulent jet in a subsonic slipstream; composite supersonic jets; the principal gas-dynamic characteristics of the processes occurring in gas-jet-driven shock-wave generators; and the construction of models for supersonic jet flows. For individual items see A84-16902 to A84-16918

  10. "Waveguidability" of idealized jets

    NASA Astrophysics Data System (ADS)

    Manola, Iris; Selten, Frank; Vries, Hylke; Hazeleger, Wilco

    2013-09-01

    It is known that strong zonal jets can act as waveguides for Rossby waves. In this study we use the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis data to analyze the connection between jets and zonal waves at timescales beyond 10 days. Moreover, a barotropic model is used to systematically study the ability of idealized jets to trap Rossby wave energy ("waveguidability") as a function of jet strength, jet width, and jet location. In general, strongest waveguidability is found for narrow, fast jets. In addition, when the stationary wave number is integer, a resonant response is found through constructive interference. In Austral summer, the Southern Hemispheric jet is closest to the idealized jets considered and it is for this season that similar jet-zonal wave relationships are identified in the ECMWF reanalysis data.

  11. Influence of impact conditions on plasma generation during hypervelocity impact by aluminum projectile

    NASA Astrophysics Data System (ADS)

    Song, Weidong; Lv, Yangtao; Li, Jianqiao; Wang, Cheng; Ning, Jianguo

    2016-07-01

    For describing hypervelocity impact (relative low-speed as related to space debris and much lower than travelling speed of meteoroids) phenomenon associated with plasma generation, a self-developed 3D code was advanced to numerically simulate projectiles impacting on a rigid wall. The numerical results were combined with a new ionization model which was developed in an early study to calculate the ionized materials during the impact. The calculated results of ionization were compared with the empirical formulas concluded by experiments in references and a good agreement was obtained. Then based on the reliable 3D numerical code, a series of impacts with different projectile configurations were simulated to investigate the influence of impact conditions on hypervelocity impact generated plasma. It was found that the form of empirical formula needed to be modified. A new empirical formula with a critical impact velocity was advanced to describe the velocity dependence of plasma generation and the parameters of the modified formula were ensured by the comparison between the numerical predictions and the empirical formulas. For different projectile configurations, the changes of plasma charges with time are different but the integrals of charges on time almost stayed in the same level.

  12. Hypervelocity gun. [using both electric and chemical energy for projectile propulsion

    NASA Technical Reports Server (NTRS)

    Ford, F. C.; Biehl, A. J. (Inventor)

    1965-01-01

    A velocity amplifier system which uses both electric and chemical energy for projectile propulsion is provided in a compact hypervelocity gun suitable for laboratory use. A relatively heavy layer of a tamping material such as concrete encloses a loop of an electrically conductive material. An explosive charge at least partially surrounding the loop is adapted to collapse the loop upon detonation of the charge. A source of electricity charges the loop through two leads, and an electric switch which is activated by the charge explosive charge, disconnects the leads from the source of electricity and short circuits them. An opening in the tamping material extends to the loop and forms a barrel. The loop, necked down in the opening, forms the sabot on which the projectile is located. When the loop is electrically charged and the explosive detonated, the loop is short circuited and collapsed thus building up a magnetic field which acts as a sabot catcher. The sabot is detached from the loop and the sabot and projectile are accelerated to hypervelocity.

  13. Analysis of simulated hypervelocity impacts on a titanium fuel tank from the Salyut 7 space station

    NASA Astrophysics Data System (ADS)

    Jantou, V.; McPhail, D. S.; Chater, R. J.; Kearsley, A.

    2006-07-01

    The aim of this project was to gain a better understanding of the microstructural effects of hypervelocity impacts (HVI) in titanium alloys. We investigated a titanium fuel tank recovered from the Russian Salyut 7 space station, which was launched on April 19, 1982 before being destroyed during an un-controlled re-entry in 1991, reportedly scattering debris over parts of South America. Several sections were cut out from the tank in order to undergo HVI simulations using a two-stage light gas gun. In addition, a Ti-6Al-4V alloy was studied for further comparison. The crater morphologies produced were successfully characterised using microscope-based white light interferometry (Zygo ® Corp, USA), while projectile remnants were identified via secondary ion mass spectrometry (SIMS). Microstructural alterations were investigated using focused ion beam (FIB) milling and depth profiling, as well as transmission electron microscopy (TEM). There was evidence of a very high density of dislocations in the vicinity of the crater. The extent of the deformation was localised in a region of about one to two radii of the impact craters. No notable differences were observed between the titanium alloys used during the hypervelocity impact tests.

  14. Determine ISS Soyuz Orbital Module Ballistic Limits for Steel Projectiles Hypervelocity Impact Testing

    NASA Technical Reports Server (NTRS)

    Lyons, Frankel

    2013-01-01

    A new orbital debris environment model (ORDEM 3.0) defines the density distribution of the debris environment in terms of the fraction of debris that are low-density (plastic), medium-density (aluminum) or high-density (steel) particles. This hypervelocity impact (HVI) program focused on assessing ballistic limits (BLs) for steel projectiles impacting the enhanced Soyuz Orbital Module (OM) micrometeoroid and orbital debris (MMOD) shield configuration. The ballistic limit was defined as the projectile size on the threshold of failure of the OM pressure shell as a function of impact speeds and angle. The enhanced OM shield configuration was first introduced with Soyuz 30S (launched in May 2012) to improve the MMOD protection of Soyuz vehicles docked to the International Space Station (ISS). This test program provides HVI data on U.S. materials similar in composition and density to the Russian materials for the enhanced Soyuz OM shield configuration of the vehicle. Data from this test program was used to update ballistic limit equations used in Soyuz OM penetration risk assessments. The objective of this hypervelocity impact test program was to determine the ballistic limit particle size for 440C stainless steel spherical projectiles on the Soyuz OM shielding at several impact conditions (velocity and angle combinations). This test report was prepared by NASA-JSC/ HVIT, upon completion of tests.

  15. Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas.

    PubMed

    Goel, A; Tarantino, P M; Lauben, D S; Close, S

    2015-04-01

    An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments. PMID:25933852

  16. Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas

    NASA Astrophysics Data System (ADS)

    Goel, A.; Tarantino, P. M.; Lauben, D. S.; Close, S.

    2015-04-01

    An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments.

  17. Design and testing of miniaturized plasma sensor for measuring hypervelocity impact plasmas

    SciTech Connect

    Goel, A. Tarantino, P. M.; Lauben, D. S.; Close, S.

    2015-04-15

    An increasingly notable component of the space environment pertains to the impact of meteoroids and orbital debris on spacecraft and the resulting mechanical and electrical damages. Traveling at speeds of tens of km/s, when these particles, collectively referred to as hypervelocity particles, impact a satellite, they vaporize, ionize, and produce a radially expanding plasma that can generate electrically harmful radio frequency emission or serve as a trigger for electrostatic discharge. In order to measure the flux, composition, energy distribution, and temperature of ions and electrons in this plasma, a miniaturized plasma sensor has been developed for carrying out in-situ measurements in space. The sensor comprises an array of electrostatic analyzer wells split into 16 different channels, catering to different species and energy ranges in the plasma. We present results from numerical simulation based optimization of sensor geometry. A novel approach of fabricating the sensor using printed circuit boards is implemented. We also describe the test setup used for calibrating the sensor and show results demonstrating the energy band pass characteristics of the sensor. In addition to the hypervelocity impact plasmas, the plasma sensor developed can also be used to carry out measurements of ionospheric plasma, diagnostics of plasma propulsion systems, and in other space physics experiments.

  18. Numerical Simulation on the Damage Characteristics of Ice Targets by Projectile Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wei, Gang; Mu, Zhong-Cheng

    2009-06-01

    Interpretation of cratering records on planetary surfaces including the Earth has primarily been concerned with rocky surfaces, most notably the lunar surface and more recently Mars and Venus. Recently, the survey of craters on icy surfaces in the Solar System has been augmented by data from spacecraft close encounters, such as the Galileo mission to the jovian system. To fully understand these cratering records, the physics of hypervelocity impacts needs to be understood. The numerical simulation on the damage characteristics of ice targets by projectile normally hypervelocity impact has been performed using the hydro-code AUTODYN. The 1mm spherical projectile is aluminum 2017 alloy. The targets are water ice. The simulation velocities were in the range of 1km/s-10km/s. The material models are consisted of Tillotson and Polynomial equation of state, Mohr-Coulomb and Johnson-Holmqiust strength model and Johnson-Holmqiust and principle stress failure model. The damage characteristics include peak ejection angle, peak temperature and pressure, maximum crater depth and diameter etc. The simulation results are given and compared with the experimental results of Burchell 2002. The simulation results are consistent very well with the experimental results.

  19. Numerical Simulation on the Damage Characteristics of Ice Targets by Projectile Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Wei, Zhang; Gang, Wei; Zhong-Cheng, Mu; Chang, Liu

    2009-12-01

    Interpretation of cratering records on planetary surfaces including the Earth has primarily been concerned with rocky surfaces, most notably the lunar surface and more recently Mars and Venus. Recently, the survey of craters on icy surfaces in the Solar System has been augmented by data from spacecraft close encounters, such as the Galileo mission to the Jovian system. To fully understand these cratering records, the physics of hypervelocity impacts needs to be understood. The numerical simulation on the damage characteristics of ice targets by projectile normal hypervelocity impact has been performed using the hydro-code AUTODYN. The 1 mm spherical projectile is aluminum 2017 alloy. The targets are water ice. The simulation velocities were in the range of 1 km/s-10 km/s. The damage characteristics include peak ejection angle, maximum crater depth and diameter etc. The simulation results are given and compared with the experimental results of Shrine et al. 2002. The simulation results are consistent with the experimental results.

  20. Bacillus subtilis Spores on Artificial Meteorites Survive Hypervelocity Atmospheric Entry: Implications for Lithopanspermia

    NASA Astrophysics Data System (ADS)

    Fajardo-Cavazos, Patricia; Link, Lindsey; Melosh, H. Jay; Nicholson, Wayne L.

    2005-12-01

    An important but untested aspect of the lithopanspermia hypothesis is that microbes situated on or within meteorites could survive hypervelocity entry from space through Earth's atmosphere. The use of high-altitude sounding rockets to test this notion was explored. Granite samples permeated with spores of Bacillus subtilis strain WN511 were attached to the exterior telemetry module of a sounding rocket and launched from White Sands Missile Range, New Mexico into space, reaching maximum atmospheric entry velocity of 1.2 km/s. Maximum recorded temperature during the flight was measured at 145°C. The surfaces of the post-flight granite samples were swabbed and tested for recovery and survival of WN511 spores, using genetic markers and the unique DNA fingerprint of WN511 as recovery criteria. Spore survivors were isolated at high frequency, ranging from 1.2% to 4.4% compared with ground controls, from all surfaces except the forward-facing surface. Sporulation-defective mutants were noted among the spaceflight survivors at high frequency (4%). These experiments constitute the first report of spore survival to hypervelocity atmospheric transit, and indicate that sounding rocket flights can be used to model the high-speed atmospheric entry of bacteria-laden artificial meteorites.

  1. HYPERFUSE: a hypervelocity inertial confinement system for fusion energy production and fission waste transmutation

    SciTech Connect

    Makowitz, H; Powell, J R; Wiswall, R

    1980-01-01

    Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from an LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., /sup 137/Cs, /sup 90/Sr, /sup 129/I, /sup 99/Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,..cap alpha..), (n,..gamma..), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R=1.0 to 3.0) requirements.

  2. A Comparative Analysis of the Performance of Long-Range Hypervelocity Vehicles

    NASA Technical Reports Server (NTRS)

    Eggers, Alfred J , Jr; Allen, H Julian; Neice, Stanford E

    1958-01-01

    Long-range hypervelocity vehicles are studied in terms of their motion in powered flight. Powered flight is analyzed for an idealized propulsion system which approximates rocket motors. Unpowered flight is characterized by a return to earth along a ballistic, skip, or glide trajectory. Only those trajectories are treated which yield the maximum range for a given velocity at the end of powered flight. Aerodynamic heating is treated in a manner similar to that employed previously by the senior authors in studying ballistic missiles (NACA rep. 1381), with the exception that radiant as well as convective heat transfer is considered in connection with glide and skip vehicles. As a final performance consideration, it is shown that on the basis of equal ratios of mass at take-off to mass at the end of powered flight, the hypervelocity vehicle compares favorably with the supersonic airplane for ranges in the neighborhood of and greater than one half the circumference of the earth. In the light of this and previous findings, it is concluded that the ballistic and glide vehicles have, in addition to the advantages usually ascribed to great speed, the attractive possibility of providing relatively efficient long-range flight.

  3. Experimental technique to launch flier-plates representing orbital debris to hypervelocities

    SciTech Connect

    Chhabildas, L.C.; Boslough, M.B.

    1992-01-01

    Very high driving pressures (tens or hundreds of GPa), are required to accelerate flier plates to hypervelocities. This loading pressure pulse on the flier plates must be nearly shockless to prevent the plate from melting or vaporizing. This is accomplished by using graded-density impactors referred to as pillows.'' When this graded-density material is used to impact a flier-plate in a modified two-stage light gas gun, nearly shockless megabar pressures are introduced into the flier plate. The pressure pulses must also be tailored to prevent spallation of the flier-plate. This technique has been used to launch nominally 1-mm-thick aluminum, magnesium and titanium (gram-size) intact plates to 10.4 km/s, and 0.5-mm-thick aluminum and titanium (half-gram size) intact plates to 12.2 km/s. This is the highest mass-velocity capability attained with laboratory launchers to date, and should open up new regimes of impact physics and lethality studies related to space sciences for laboratory investigations. In particular, the mass-velocity capability of this newly developed hypervelocity launcher meets the average specifications of the space debris environment, and is therefore expected to be a useful tool to evaluate the effects of debris impact on space structures and debris shields.

  4. Experimental technique to launch flier-plates representing orbital debris to hypervelocities

    SciTech Connect

    Chhabildas, L.C.; Boslough, M.B.

    1992-12-31

    Very high driving pressures (tens or hundreds of GPa), are required to accelerate flier plates to hypervelocities. This loading pressure pulse on the flier plates must be nearly shockless to prevent the plate from melting or vaporizing. This is accomplished by using graded-density impactors referred to as ``pillows.`` When this graded-density material is used to impact a flier-plate in a modified two-stage light gas gun, nearly shockless megabar pressures are introduced into the flier plate. The pressure pulses must also be tailored to prevent spallation of the flier-plate. This technique has been used to launch nominally 1-mm-thick aluminum, magnesium and titanium (gram-size) intact plates to 10.4 km/s, and 0.5-mm-thick aluminum and titanium (half-gram size) intact plates to 12.2 km/s. This is the highest mass-velocity capability attained with laboratory launchers to date, and should open up new regimes of impact physics and lethality studies related to space sciences for laboratory investigations. In particular, the mass-velocity capability of this newly developed hypervelocity launcher meets the average specifications of the space debris environment, and is therefore expected to be a useful tool to evaluate the effects of debris impact on space structures and debris shields.

  5. Nitric oxide emission spectroscopy measurements in a hypervelocity post-shock flow field

    NASA Astrophysics Data System (ADS)

    Swantek, Andrew; Austin, Joanna

    2012-11-01

    In hypervelocity flight conditions, typical of sub-orbital and reentry trajectories, the coupling between the fluid mechanics and the thermochemistry of the flow becomes important. In the current work, we use an expansion tube facility to accelerate air to hypervelocity test conditions (stagnation enthalpy 8MJ/kg, velocity 3.8 km/s). A double wedge model is used to generate an oblique shock, a strong bow shock, and a shock-boundary-layer interaction which is known to be very sensitive to the thermochemical state of the gas. We investigate the nitric oxide emission signal in the ultraviolet region (220-255 nm, A-X transition) at four spatial locations downstream of the bow shock (0, 2, 4, and 6 mm). An in-house code is used to simulate the spectrum in this region and thus obtain a temperature fit. Temperatures are observed to decrease when traversing downstream, starting at approximately the frozen temperature (about 7700 K) at the location of the shock (0 mm). The furthest downstream point deviates from this trend, potentially due to heating in a shear layer formed in the flow field. The flow field is seen to be in non-equilibrium in this region, as temperatures do not reach the equilibrium temperature (about 3900 K). This work was supported by an AFOSR award FA9550-11-1-0129 with Dr John Schmisseur as Program Manager.

  6. Hypervelocity Impact (HVI). Volume 2; WLE Small-Scale Fiberglass Panel Flat Multi-Layer Targets A-1, A-2, and B-1

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Ziola, Steven M.

    2007-01-01

    During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Targets A-1, A-2, and B-2 was to study hypervelocity impacts through multi-layered panels simulating Whipple shields on spacecraft. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

  7. Momentum distribution in debris cloud during hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Lemaster, P.; Mount, A.; Zee, R. H.

    1992-01-01

    The long term operation of the Space Station Freedom requires a scheme to protect it from high velocity impacts by both man-made particles and micrometeor fragments. One such scheme is the use of metal plates to serve as shields against such orbital debris. These 'bumper' plates, as they are referred to, serve to break up any incident particle and redistribute its momentum over a larger area. It is therefore necessary to determine the momentum distribution within the debris cloud produced by such collisions in order to evaluate a materials effectiveness at accomplishing this task. This paper details the design and development of an innovative device which has made this possible. Momentum profiles were obtained for a series of test conditions. Total momentum values in the debris cloud were then calculated from these profiles. These results indicated that a momentum amplification exists with a multiplication factor of between 2 and 3. Thus the role of the bumper to serve as a means for momentum redistribution and not reduction was verified.

  8. Trace metal distribution and control in the pilot-scale bubbling fluidized bed combustor equipped with the pulse-jet fabric filter, limestone injection, and the humidification reactor.

    PubMed

    Kouvo, Petri

    2003-04-01

    This work focused on trace metal behavior and removal in a fabric filter or in a humidification reactor during the cofiring of sawdust and refuse-derived fuels (RDFs) in a pilot-scale bubbling fluidized bed (BFB) boiler. Trace metal emissions measurements before and after the fabric filter revealed that removal efficiency in the fabric filter was in the range of 80-100%, and that the European Union (EU) Directive on Incineration of Waste restrictions for trace metal emissions are easily achieved even if addition of RDFs substantially increases the concentration of trace metals in fuel blends. Limestone injection enhanced the removal of As and Se but had no noticeable effect on the removal of other trace metals. Extensive formation of HgCl2 and condensation on fly ash particles during sawdust plus 40% RDF cofiring resulted in a 92% Hg removal efficiency in the fabric filter. Limestone injection had no effect on the Hg removal in the fabric filter but decreased the Hg removal in a humidification reactor from 40 to 28%. Results of the bed material and fly ash analysis suggested capture of Cu, Pb, Mn, Ni, and Zn in the bed material but also suggested that these metals may be released from the bed if the fuel characteristics or process conditions are changed. PMID:12708504

  9. Contrasting H-mode behaviour with deuterium fuelling and nitrogen seeding in the all-carbon and metallic versions of JET

    NASA Astrophysics Data System (ADS)

    Maddison, G. P.; Giroud, C.; Alper, B.; Arnoux, G.; Balboa, I.; Beurskens, M. N. A.; Boboc, A.; Brezinsek, S.; Brix, M.; Clever, M.; Coelho, R.; Coenen, J. W.; Coffey, I.; da Silva Aresta Belo, P. C.; Devaux, S.; Devynck, P.; Eich, T.; Felton, R. C.; Flanagan, J.; Frassinetti, L.; Garzotti, L.; Groth, M.; Jachmich, S.; Järvinen, A.; Joffrin, E.; Kempenaars, M. A. H.; Kruezi, U.; Lawson, K. D.; Lehnen, M.; Leyland, M. J.; Liu, Y.; Lomas, P. J.; Lowry, C. G.; Marsen, S.; Matthews, G. F.; McCormick, G. K.; Meigs, A. G.; Morris, A. W.; Neu, R.; Nunes, I. M.; Oberkofler, M.; Rimini, F. G.; Saarelma, S.; Sieglin, B.; Sips, A. C. C.; Sirinelli, A.; Stamp, M. F.; van Rooij, G. J.; Ward, D. J.; Wischmeier, M.; EFDA Contributors, JET

    2014-07-01

    The former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten in the divertor to mimic the surface materials envisaged for ITER. Comparisons are presented between type I H-mode characteristics in each design by examining respective scans over deuterium fuelling and impurity seeding, required to ameliorate exhaust loads both in JET at full capability and in ITER. Attention is focused upon a common high-triangularity, single-null divertor configuration at 2.5 MA, q95 ≈ 3.5 yielding the most robust all-C performance. Contrasting results between the alternative linings are found firstly in unseeded plasmas, for which purity is improved and intrinsic radiation reduced in the ITER-like wall (ILW) but normalized energy confinement is ≈30% lower than in all-C counterparts, owing to a commensurately lower (electron) pedestal temperature. Divertor recycling is also radically altered, with slower, inboard-outboard asymmetric transients at ELMs and spontaneous oscillations in between them. Secondly, nitrogen seeding elicits opposite responses in the ILW to all-C experience, tending to raise plasma density, reduce ELM frequency, and above all to recover (electron) pedestal pressure, hence global confinement, almost back to previous levels. A hitherto unrecognized role of light impurities in pedestal stability and dynamics is consequently suggested. Thirdly, while heat loads on the divertor outboard target between ELMs are successfully reduced in proportion to the radiative cooling and ELM frequency effects of N in both wall environments, more surprisingly, average power ejected by ELMs also declines in the same proportion for the ILW. Detachment between transients is simultaneously promoted. Finally, inter-ELM W sources in the ILW divertor tend to fall with N input, although core accumulation possibly due to increased particle confinement still leads to significantly less steady conditions than in all-C plasmas. This limitation of ILW H

  10. Composition of Plasma Formed from Hypervelocity Dust Impacts

    NASA Astrophysics Data System (ADS)

    Lee, N.; Close, S.; Rymer, A. M.; Mocker, A.

    2012-12-01

    Dust impacts can occur on all solar system bodies but are especially prevalent in the case of the Saturnian moons that are near or within the dust torus produced by Enceladus's plumes. Depending on the mass and charge on these plume particles, they will be influenced by both gravitational and electrodynamic forces, resulting in a range of possible impact speeds on the moons. The plasma formed upon impact can have very different characteristics depending on impact speed and on the electric field due to surface charging at the impact point. Through recent tests conducted at the Max Planck Institute for Nuclear Physics using a Van de Graaff dust accelerator, iron dust particles were electrostatically accelerated to speeds of 3-65 km/s and impacted on a variety of target materials including metallic and glassy surfaces. The target surfaces were connected to a biasing supply to represent surface charging effects. Because of the high specific kinetic energy of the dust particles, upon impact they vaporize along with part of the target surface and a fraction of this material is ionized forming a dense plasma. The impacts produced both positive and negative ions. We made measurements of the net current imparted by this expanding plasma at a distance of several centimeters from the impact point. By setting the bias of the target, we impose an electric field on the charge population, allowing a measurement of plasma composition through time of flight analysis. The figure shows representative measurements of the net current measured by a retarding potential analyzer (RPA) from separate 18 and 19 km/s impacts of 7 fg particles on a glassy surface that was negatively and positively biased, respectively. This target was an optical solar reflector donated by J. Likar of Lockheed Martin for these experiments. These results show that ions of both positive and negative charge can be formed through the mechanism of dust impacts, and has implications on the surface plasma environment

  11. Stretched Inertial Jets

    NASA Astrophysics Data System (ADS)

    Ghabache, Elisabeth; Antkowiak, Arnaud; Seon, Thomas; Villermaux, Emmanuel

    2015-11-01

    Liquid jets often arise as short-lived bursting liquid flows. Cavitation or impact-driven jets, bursting champagne bubbles, shaped-charge jets, ballistospores or drop-on-demand inkjet printing are a few examples where liquid jets are suddenly released. The trademark of all these discharge jets is the property of being stretched, due to the quenching injection. the present theoretical and experimental investigation, the structure of the jet flow field will be unraveled experimentally for a few emblematic occurrences of discharge jets. Though the injection markedly depends on each flow configuration, the jet velocity field will be shown to be systematically and rapidly attracted to the universal stretching flow z/t. The emergence of this inertial attractor actually only relies on simple kinematic ingredients, and as such is fairly generic. The universality of the jet velocity structure will be discussed.

  12. Asteroid deflection using a kinetic impactor: Insights from hypervelocity impact experiments

    NASA Astrophysics Data System (ADS)

    Hoerth, Tobias; Schäfer, Frank

    2016-04-01

    Within the framework of the planned AIDA mission [1], an impactor spacecraft (DART) hits the second component of the asteroid Didymos at hypervelocity. The impact crater will be observed from the AIM spacecraft and an observation of the ejecta plume is possible [1]. This allows conclusions to be drawn about the physical properties of the target material, and the momentum transfer will be studied [1]. In preparation for this mission, hypervelocity impact experiments can provide valuable information about the outcome of an impact event as a function of impactor and target material properties and, thus, support the interpretation of the data from the DART impact. In addition, these impact experiments provide an important means to validate numerical impact simulations required to simulate large-scale impacts that cannot be studied in laboratory experiments. Impact experiments have shown that crater morphology and size, crater growth and ejecta dynamics strongly depend on the physical properties of the target material [2]. For example, porous materials like sandstone lead to a shallower and slower ejection than low-porous materials like quartzite, and the cratering efficiency is reduced in porous targets leading to a smaller amount of ejected mass [3]. These phenomena result in a reduced momentum multiplication factor (often called "beta-value"), i.e. the ratio of the change in target momentum after the impact and the momentum of the projectile is smaller for porous materials. Hypervelocity impact experiments into target materials with different porosities and densities such as quartzite (2.9 %, 2.6 g/cm3), sandstone (25.3 %, 2 g/cm3), limestone (31 %, 1.8 g/cm3), and highly porous aerated concrete (87.5 %, 0.4 g/cm3) were conducted. Projectile velocities were varied between about 3 km/s and almost 7 km/s. A ballistic pendulum was used to measure the momentum transfer. The material strength required for scaling laws was determined for all target materials. The highest

  13. Modeling the oblique hypervelocity impact of orbital debris particles on spacecraft structures using elementary shock physics

    NASA Astrophysics Data System (ADS)

    Ebrahim, Ahmed Roushdy

    1998-11-01

    During their missions in space, spacecraft are subjected to high velocity impacts by orbital debris particles. Such impacts are expected to occur at non-normal angles of incidence and can cause severe damage to the spacecraft as well as its internal and external flight- critical systems. In order to ensure crew safety as well as the proper function of internal and external spacecraft systems, the characteristics of the debris clouds generated from orbital debris impacts must be determined. The effects of these debris clouds can then be considered in the design of spacecraft protective systems. In this dissertation, a new first principles- based analytical model is developed for the characterization of the penetration and ricochet debris clouds created by an oblique hypervelocity impact of a spherical projectile on a thin bumper plate. This model employs normal and oblique shock wave theories to characterize the penetration and ricochet processes. The model formulation consists of two mechanisms. The first predicts the leading edge velocities and trajectories of centers of mass of the normal and in-line debris clouds created in an oblique hypervelocity impact of a spherical projectile on a thin plate. The second predicts the leading edge velocity and trajectory of center of mass of ricochet debris cloud. In each of these two mechanisms, a new functional form of a reflected Hugoniot is developed to approximate the release of the bumper material. It was found that, unlike normal impact where there is only one reflected Hugoniot, the release of the bumper material in case of an oblique impact is approximated by a set of reflected Hugoniots that depends upon the impact obliquity angle. The methodology for characterizing the debris clouds created in an oblique hypervelocity impact uses the conservation equations that, governing the impact event, calculates the debris clouds' leading edge velocities and trajectories of debris cloud centers-of- mass using an elementary

  14. Aerothermal Performance Constraints for Hypervelocity Small Radius Unswept Leading Edges and Nosetips

    NASA Technical Reports Server (NTRS)

    Kolodziej, Paul

    1997-01-01

    Small radius leading edges and nosetips were utilized to minimize wave drag in early hypervelocity vehicle concepts until further analysis demonstrated that extreme aerothermodynamic heating would cause severe ablation or blunting of the available thermal protection system materials. Recent studies indicate that ultrahigh temperature ceramic (UHTC) materials are shape stable at temperatures approaching 3033 K and will be available for use as sharp UHTC leading edge components in the near future. Aerothermal performance constraints for sharp components made from these materials are presented in this work to demonstrate the effects of convective blocking, surface catalycity, surface emissivity, and rarefied flow effects on steady state operation at altitudes from sea level to 90 km. These components are capable of steady state operation at velocities up to 7.9 km/s at attitudes near 90 km.

  15. Simulation of Hypervelocity Impact on Aluminum-Nextel-Kevlar Orbital Debris Shields

    NASA Technical Reports Server (NTRS)

    Fahrenthold, Eric P.

    2000-01-01

    An improved hybrid particle-finite element method has been developed for hypervelocity impact simulation. The method combines the general contact-impact capabilities of particle codes with the true Lagrangian kinematics of large strain finite element formulations. Unlike some alternative schemes which couple Lagrangian finite element models with smooth particle hydrodynamics, the present formulation makes no use of slidelines or penalty forces. The method has been implemented in a parallel, three dimensional computer code. Simulations of three dimensional orbital debris impact problems using this parallel hybrid particle-finite element code, show good agreement with experiment and good speedup in parallel computation. The simulations included single and multi-plate shields as well as aluminum and composite shielding materials. at an impact velocity of eleven kilometers per second.

  16. A Dipole on the Sky: Predictions for Hypervelocity Stars from the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Boubert, Douglas; Evans, N. Wyn

    2016-07-01

    We predict the distribution of hypervelocity stars (HVSs) ejected from the Large Magellanic Cloud (LMC), under the assumption that the dwarf galaxy hosts a central massive black hole (MBH). For the majority of stars ejected from the LMC, the orbital velocity of the LMC has contributed a significant fraction of their galactic rest-frame velocity, leading to a dipole density distribution on the sky. We quantify the dipole using spherical harmonic analysis and contrast with the monopole expected for HVSs ejected from the Galactic center (GC). There is a tendril in the density distribution that leads the LMC, which is coincident with the well-known and unexplained clustering of HVSs in the constellations of Leo and Sextans. Our model is falsifiable since it predicts that Gaia will reveal a large density of HVSs in the southern hemisphere.

  17. Vulnerability analysis of a pressurized aluminum composite vessel against hypervelocity impacts

    NASA Astrophysics Data System (ADS)

    Hereil, Pierre-Louis; Plassard, Fabien; Mespoulet, Jérôme

    2015-09-01

    Vulnerability of high pressure vessels subjected to high velocity impact of space debris is analyzed with the response of pressurized vessels to hypervelocity impact of aluminum sphere. Investigated tanks are CFRP (carbon fiber reinforced plastics) overwrapped Al vessels. Explored internal pressure of nitrogen ranges from 1 bar to 300 bar and impact velocity are around 4400 m/s. Data obtained from Xrays radiographies and particle velocity measurements show the evolution of debris cloud and shock wave propagation in pressurized nitrogen. Observation of recovered vessels leads to the damage pattern and to its evolution as a function of the internal pressure. It is shown that the rupture mode is not a bursting mode but rather a catastrophic damage of the external carbon composite part of the vessel.

  18. Hypervelocity impact study: The effect of impact angle on crater morphology

    NASA Technical Reports Server (NTRS)

    Crawford, Gary; Hill, David; Rose, Frank E.; Zee, Ralph; Best, Steve; Crumpler, Mike

    1993-01-01

    The Space Power Institute (SPI) of Auburn University has conducted preliminary tests on the effects of impact angle on crater morphology for hypervelocity impacts. Copper target plates were set at angles of 30 deg and 60 deg from the particle flight path. For the 30 deg impact, the craters looked almost identical to earlier normal incidence impacts. The only difference found was in the apparent distribution of particle residue within the crater, and further research is needed to verify this. The 60 deg impacts showed marked differences in crater symmetry, crater lip shape, and particle residue distribution. Further research on angle effects is planned, because the particle velocities for these shots were relatively slow (7 km/s or less).

  19. The effect of impact angle on craters formed by hypervelocity particles

    NASA Technical Reports Server (NTRS)

    Hill, David C.; Rose, M. Frank; Best, Steve R.; Crumpler, Michael S.; Crawford, Gary D.; Zee, Ralph H.-C.; Bozack, Michael J.

    1995-01-01

    The Space Power Institute (SPI) at Auburn University has conducted experiments on the effects of impact angle on crater morphology and impactor residue retention for hypervelocity impacts. Copper target plates were set at angles of 30 deg, 45 deg, 60 deg, and 75 deg from the particle flight path. For the 30 deg and 45 deg impacts, in the velocity regime greater than 8 km s(exp -1) the resultant craters are almost identical to normal incidence impacts. The only difference found was in the apparent distribution of particle residue within the crater, and further research is needed to verify this. The 60 deg and 75 deg impacts showed marked differences in crater symmetry, crater lip shape, and particle residue distribution in the same velocity regime. Impactor residue shock fractionation effects have been quantified in first-order. It is concluded that a combination of analysis techniques can yield further information on impact velocity, direction, and angle of incidence.

  20. Plasma flow and fast particles in a hypervelocity accelerator - A color presentation. [micrometeoroid simulation

    NASA Technical Reports Server (NTRS)

    Igenbergs, E. B.; Cour-Palais, B.; Fisher, E.; Stehle, O.

    1975-01-01

    A new concept for particle acceleration for micrometeoroid simulation was developed at NASA Marshall Space Flight Center, using a high-density self-luminescent fast plasma flow to accelerate glass beads (with a diameter up to 1.0 mm) to velocities between 15-20 km/sec. After a short introduction to the operation of the hypervelocity range, the eight-converter-camera unit used for the photographs of the plasma flow and the accelerated particles is described. These photographs are obtained with an eight-segment reflecting pyramidal beam splitter. Wratten filters were mounted between the beam splitter and the converter tubes of the cameras. The photographs, which were recorded on black and white film, were used to make the matrices for the dye-color process, which produced the prints shown.

  1. Threshold for plasma phase transition of aluminum single crystal induced by hypervelocity impact

    SciTech Connect

    Ju, Yuanyuan; Zhang, Qingming

    2015-12-15

    Molecular dynamics method is used to study the threshold for plasma phase transition of aluminum single crystal induced by hypervelocity impact. Two effective simulation methods, piston-driven method and multi-scale shock technique, are used to simulate the shock wave. The simulation results from the two methods agree well with the experimental data, indicating that the shock wave velocity is linearly dependent on the particle velocity. The atom is considered to be ionized if the increase of its internal energy is larger than the first ionization energy. The critical impact velocity for plasma phase transition is about 13.0 km/s, corresponding to the threshold of pressure and temperature which is about 220 GPa and 11.0 × 10{sup 3 }K on the shock Hugoniot, respectively.

  2. Ground Testing Of Hypervelocity Impact Effects Of Micrometeoroids And Space Debris On Solar Arrays

    NASA Astrophysics Data System (ADS)

    Schimmerohn, Martin; Rott, Martin; Gerhard, Andreas; Osterholz, Jens; Schafer, Frank; D'Accolti, Gianfelice

    2011-10-01

    Solar arrays are the satellite component most exposed to micrometeoroid and space debris (MM/SD) impacts. The damage potential of hypervelocity impacts (HVI) is characterized by considerable energy released at the impact interface leading to mechanical damage and the generation of plasma. Impact experiments performed in the past indicate that the impact plasma can induce arcing, which consequently may lead to permanent power losses as known from electrostatic discharges. An ESA study is currently ongoing, the objective of which is to study and test the susceptibility of state-of-the art solar arrays to HVI. This paper describes potential failure modes, a ground testing approach to simulate them and its implementation for the test campaign, which will be performed at Fraunhofer EMI using a light gas gun and at Technische Universität München using a plasma-dynamic accelerator. Solar array simulation equipment and comprehensive plasma diagnostics are to be applied for ground testing.

  3. Hypervelocity Impact Testing of IM7/977-3 with Micro-Sized Particles

    NASA Technical Reports Server (NTRS)

    Smith, J. G.; Jegley, D. C.; Siochi, E. J.; Wells, B. K.

    2010-01-01

    Ground-based hypervelocity imapct testing was conducted on IM7/977-3 quasi-isotropic flat panels at normal incidence using micron-sized particles (i.e. less than or equal to 100 microns) of soda lime glass and olivine. Testing was performed at room temperature (RT) and 175 C with results from the 175 C test compared to those obtained at RT. Between 10 and 30 particles with velocities ranging from 5 to 13 km/s impacted each panel surface for each test temperature. Panels were ultrasonically scanned prior to and after impact testing to assess internal damage. Post-impact analysis included microscopic examination of the surface, determination of particle speed and location, and photomicroscopy for microcrack assessment. Internal damage was observed by ultrasonic inspection on panels impacted at 175 C, whereas damage for the RT impacted panels was confined to surface divets/craters as determined by microscopic analysis.

  4. Finite element analysis of hypervelocity impact behaviour of CFRP-Al/HC sandwich panel

    NASA Astrophysics Data System (ADS)

    Phadnis, Vaibhav A.; Silberschmidt, Vadim V.

    2015-09-01

    The mechanical response of CFRP-Al/HC (carbon fibre-reinforced/epoxy composite face sheets with Al honeycomb core) sandwich panels to hyper-velocity impact (up to 1 km/s) is studied using a finite-element model developed in ABAQUS/Explicit. The intraply damage of CFRP face sheets is analysed by mean of a user-defined material model (VUMAT) employing a combination of Hashin and Puck criteria, delamination modelled using cohesive-zone elements. The damaged Al/HC core is assessed on the basis of a Johnson Cook dynamic failure model while its hydrodynamic response is captured using the Mie-Gruneisen equation of state. The results obtained with the developed finite-element model showed a reasonable correlation to experimental damage patterns. The surface peeling of both face sheets was evident, with a significant delamination around the impact location accompanied by crushing HC core.

  5. Hypervelocity dust impacts on the Wind spacecraft: Correlations between Ulysses and Wind interstellar dust detections

    NASA Astrophysics Data System (ADS)

    Wood, S. R.; Malaspina, David M.; Andersson, Laila; Horanyi, Mihaly

    2015-09-01

    The Wind spacecraft is positioned just sunward of Earth at the first Lagrange point, while the Ulysses spacecraft orbits above and below the ecliptic plane crossing the ecliptic as far from the Sun as the orbit of Jupiter (˜5 AU). While Wind does not carry a dedicated dust detector, we demonstrate the ability of Wind electric field measurements to detect hypervelocity dust impacts through their impact plasma signatures. Interstellar dust (ISD) and interplanetary dust particles are differentiated based on a yearly modulation of the ISD flux. Measurements of ISD flux variation by Wind are found to be in good agreement with ISD flux variation measured by Ulysses. While measurements of the ISD flow direction through the Solar System determined by Wind could not be directly compared to those from Ulysses, strong variation in ISD flow direction was observed during similar time periods by both spacecraft.

  6. Properties of largest fragment produced by hypervelocity impact of aluminum spheres with thin aluminum sheets

    NASA Technical Reports Server (NTRS)

    Piekutowski, Andrew J.

    1992-01-01

    Results are presented from hypervelocity impact tests in which 1.275 g spheres of 2017-T4 Al alloy were fired at normal incidence at eight thicknesses of 6061-T6 Al alloy sheets, with impact velocity of about 6.7 km/sec; additional data are presented for smaller and larger spheres than these, in the cases of other Al alloy impact bumpers. A large fragment of the projectile is observable at the center of the debris clouds generated upon impact. The velocity of these large fragments decreased continuously with increasing bumper thickness/projectile diameter ratio, from 99 percent to less than 80 percent of impact velocity; there is a linear increase in the size of the central projectile fragment with decreasing shock-induced stress in the projectile.

  7. Magnetic field amplification and generation in hypervelocity meteoroid impacts with application to lunar paleomagnetism

    NASA Technical Reports Server (NTRS)

    Hood, L. L.; Vickery, A.

    1984-01-01

    A one-dimensional numerical model for the expansion of impact-produced vapor clouds is used to investigate magnetic field generation mechanisms in events such as meteor collisions with the moon. The resulting cloud properties, such as ionization fraction, electrical conductivity, radial expansion velocity, mass density, and energy density are estimated. The model is initiated with the peak shock states and pressure thresholds for incipient and complete vaporization of anorthosite lunar surface materials by iron and GA composition meteorites. The expansion of the spherical gas cloud into a vacuum was traced with a one-dimensional explicit lagrangian hydrodynamic code. The hypervelocity impact plasmas produced are found to be significant in the amplitudes and orientations of the magnetic fields generated. An ambient magnetic field could have been provided by the core dynamo, which would have interacted with the expanding plasmas and formed induced paleomagnetic fields. Several other field-contribution mechanisms are discussed and discarded as potential remanent magnetism contributors.

  8. Modelling hypervelocity impact fracture of ceramic panels using a mesh-free method

    NASA Astrophysics Data System (ADS)

    Das, R.; Mikhail, J.; Cleary, P. W.

    2010-06-01

    This paper studies the application of Smoothed Particle Hydrodynamics (SPH) for modelling hyper-velocity impact fracture and fragmentation in ceramic panels. Numerical modelling of complex fracture processes is important to understand the fundamental failure mechanisms in a variety of systems. Finite Element Method (FEM) is the mesh-based method conventionally applied to numerical simulation of fracture and fragmentation. However, the mesh generation and manipulation do not often provide the desired accuracy of the solutions, especially in problems with extreme deformations and discontinuities. To overcome this, here we use a mesh-free method called Smoothed Particle Hydrodynamic (SPH) to investigate the three-dimensional fracture of ceramic panels. The effect of impact speed on the fracture pattern and energy transfer is analysed. The SPH simulations are found to be robust in understanding the fracture mechanisms and in providing crucial design parameters.

  9. Magnetic field amplification and generation in hypervelocity meteoroid impacts with application to lunar paleomagnetism

    SciTech Connect

    Hood, L.L.; Vickery, A.

    1984-11-15

    A one-dimensional numerical model for the expansion of impact-produced vapor clouds is used to investigate magnetic field generation mechanisms in events such as meteor collisions with the moon. The resulting cloud properties, such as ionization fraction, electrical conductivity, radial expansion velocity, mass density, and energy density are estimated. The model is initiated with the peak shock states and pressure thresholds for incipient and complete vaporization of anorthosite lunar surface materials by iron and GA composition meteorites. The expansion of the spherical gas cloud into a vacuum was traced with a one-dimensional explicit lagrangian hydrodynamic code. The hypervelocity impact plasmas produced are found to be significant in the amplitudes and orientations of the magnetic fields generated. An ambient magnetic field could have been provided by the core dynamo, which would have interacted with the expanding plasmas and formed induced paleomagnetic fields. Several other field-contribution mechanisms are discussed and discarded as potential remanent magnetism contributors.

  10. Numerical Simulation of Debris Cloud Propagation inside Gas-Filled Pressure Vessels under Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Gai, F. F.; Pang, B. J.; Guan, G. S.

    2009-03-01

    In the paper SPH methods in AUTODYN-2D is used to investigate the characteristics of debris clouds propagation inside the gas-filled pressure vessels for hypervelocity impact on the pressure vessels. The effect of equation of state on debris cloud has been investigated. The numerical simulation performed to analyze the effect of the gas pressure and the impact condition on the propagation of the debris clouds. The result shows that the increase of gas pressure can reduce the damage of the debris clouds' impact on the back wall of vessels when the pressure value is in a certain range. The smaller projectile lead the axial velocity of the debris cloud to stronger deceleration and the debris cloud deceleration is increasing with increased impact velocity. The time of venting begins to occur is related to the "vacuum column" at the direction of impact-axial. The paper studied the effect of impact velocities on gas shock wave.

  11. Analysis of energy dissipation and deposition in elastic bodies impacting at hypervelocities

    NASA Technical Reports Server (NTRS)

    Medina, David F.; Allahdadi, Firooz A.

    1992-01-01

    A series of impact problems were analyzed using the Eulerian hydrocode CTH. The objective was to quantify the amount of energy dissipated locally by a projectile-infinite plate impact. A series of six impact problems were formulated such that the mass and speed of each projectile were varied in order to allow for increasing speed with constant kinetic energy. The properties and dimensions of the plate were the same for each projectile impact. The resulting response of the plate was analyzed for global Kinetic Energy, global momentum, and local maximum shear stress. The percentage of energy dissipated by the various hypervelocity impact phenomena appears as a relative change of shear stress at a point away from the impact in the plate.

  12. Hypervelocity impact tests on Space Shuttle Orbiter RCC thermal protection material. [Reinforced Carbon-Carbon laminate

    NASA Technical Reports Server (NTRS)

    Humes, D. H.

    1978-01-01

    It is noted that the Shuttle Orbiter will be more subject to meteoroid impact than previous spacecraft, due to its greater surface area and longer cumulative time in space. The Orbiter structural material, RCC, a reinforced carbon-carbon laminate with a diffused silicon carbide coating, is evaluated in terms of its resistance to hypervelocity impact. It was found that the specimens (disks with a mass of 34 g and a thickness of 5.0 mm) were cratered only on the front surface when the impact energy was 3 J or less. At 3 J, a trace of the black carbon interior was exposed. The specimens were completely penetrated when the energy was 34 J or greater.

  13. Mitigation of Autoignition Due to Premixing in a Hypervelocity Flow Using Active Wall Cooling

    NASA Technical Reports Server (NTRS)

    Axdahl, Erik; Kumar, Ajay; Wilhite, Alan

    2013-01-01

    Preinjection of fuel on the forebody of an airbreathing vehicle is a proposed method to gain access to hypervelocity flight Mach numbers. However, this creates the possibility of autoignition either near the wall or in the core of the flow, thereby consuming fuel prematurely as well as increasing the amount of pressure drag on the vehicle. The computational fluid dynamics code VULCAN was used to conduct three dimensional simulations of the reacting flow in the vicinity of hydrogen injectors on a flat plate at conditions relevant to a Mach 12 notional flight vehicle forebody to determine the location where autoignition occurs. Active wall cooling strategies were formulated and simulated in response to regions of autoignition. It was found that tangential film cooling using hydrogen or helium were both able to nearly or completely eliminate wall autoignition in the flow domain of interest.

  14. NASA Jet Noise Research

    NASA Technical Reports Server (NTRS)

    Henderson, Brenda

    2012-01-01

    The presentation highlights jet-noise research conducted in the Subsonic Fixed Wing, Supersonics, and Environmentally Responsible Aviation Projects in the Fundamental Aeronautics Program at NASA. The research efforts discussed include NASA's updated Aircraft NOise Prediction Program (ANOPP2), acoustic-analogy-based prediction tools, jet-surface-interaction studies, plasma-actuator investigations, N+2 Supersonics Validation studies, rectangular-jet experiments, twin-jet experiments, and Hybrid Wind Body (HWB) activities.

  15. Jets of incipient liquids

    NASA Astrophysics Data System (ADS)

    Reshetnikov, A. V.; Mazheiko, N. A.; Skripov, V. P.

    2000-05-01

    Jets of incipient water escaping into the atmosphere through a short channel are photographed. In some experiments. complete disintegration of the jet is observed. The relationship of this phenomenon with intense volume incipience is considered. The role of the Coanda effect upon complete opening of the jet is revealed. Measurement results of the recoil force R of the jets of incipient liquids are presented. Cases of negative thrust caused by the Coanda effect are noted. Generalization of experimental data is proposed.

  16. SILICATE DUST SIZE DISTRIBUTION FROM HYPERVELOCITY COLLISIONS: IMPLICATIONS FOR DUST PRODUCTION IN DEBRIS DISKS

    SciTech Connect

    Takasawa, S.; Nakamura, A. M.; Arakawa, M.; Seto, Y.; Sangen, K.; Setoh, M.; Machii, N.; Kadono, T.; Shigemori, K.; Hironaka, Y.; Fujioka, S.; Sano, T.; Watari, T.; Dohi, K.; Ohno, S.; Maeda, M.; Sakaiya, T.; Otani, K.; Takeuchi, T.

    2011-06-01

    Fragments generated by high-velocity collisions between solid planetary bodies are one of the main sources of new interplanetary dust particles. However, only limited ranges of collision velocity, ejecta size, and target materials have been studied in previous laboratory experiments, and the collision condition that enables the production of dust-sized particles remains unclear. We conducted hypervelocity impact experiments on silicate rocks at relative velocities of 9 to 61 km s{sup -1}, which is beyond the upper limit of previous laboratory studies. Sub-millimeter-diameter aluminum and gold spheres were accelerated by laser ablation and were shot into dunite and basalt targets. We analyzed the surfaces of aerogel blocks deployed near the targets using an electron probe micro analyzer and counted the number of particles that contained the target material. The size distributions of ejecta ranged from five to tens of microns in diameter. The total cross-sectional area of dust-sized ejecta monotonically increased with the projectile kinetic energy, independent of impact velocity, projectile diameter, and projectile and target material compositions. The slopes of the cumulative ejecta-size distributions ranged from -2 to -5. Most of the slopes were steeper than the -2.5 or -2.7 that is expected for a collisional equilibrium distribution in a collision cascade with mass-independent or mass-dependent catastrophic disruption thresholds, respectively. This suggests that the steep dust size-distribution proposed for the debris disk around HD172555 (an A5V star) could be due to a hypervelocity collision.

  17. HYPERFUSE: a hypervelocity inertial confinement system for fusion energy production and fission waste transmutation

    SciTech Connect

    Makowitz, H.; Powell, J.R.; Wiswall, R.

    1980-01-01

    Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from a LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., /sup 137/Cs, /sup 90/Sr, /sup 129/I, /sup 99/Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,..cap alpha..), (n,..gamma..), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R = 1.0 to 3.0) requirements. These studies also indicate that masses on the order of 1.0 g at densities of rho greater than or equal to 500.0 g/cm/sup 3/ are required for a practical fusion-based fission product transmutation system.

  18. Survival of the impactor during hypervelocity collisions - I. An analogue for low porosity targets

    NASA Astrophysics Data System (ADS)

    Avdellidou, C.; Price, M. C.; Delbo, M.; Ioannidis, P.; Cole, M. J.

    2016-03-01

    Recent observations of asteroidal surfaces indicate the presence of materials that do not match the bulk lithology of the body. A possible explanation for the presence of these exogenous materials is that they are products of interasteroid impacts in the Main Belt, and thus interest has increased in understanding the fate of the projectile during hypervelocity impacts. In order to gain insight into the fate of impactor, we have carried out a laboratory programme, covering the velocity range of 0.38-3.50 km s-1, devoted to measuring the survivability, fragmentation and final state of the impactor. Forsterite olivine and synthetic basalt projectiles were fired on to low porosity (<10 per cent) pure water-ice targets using the University of Kent's Light Gas Gun (LGG). We developed a novel method to identify impactor fragments which were found in ejecta and implanted into the target. We applied astronomical photometry techniques, using the SOURCE EXTRACTOR software, to automatically measure the dimensions of thousands of fragments. This procedure enabled us to estimate the implanted mass on the target body, which was found to be a few per cent of the initial mass of the impactor. We calculated an order of magnitude difference in the energy density of catastrophic disruption, Q*, between peridot and basalt projectiles. However, we found very similar behaviour of the size frequency distributions for the hypervelocity shots (>1 km s-1). After each shot, we examined the largest peridot fragments with Raman spectroscopy and no melt or alteration in the final state of the projectile was observed.

  19. Shock Tunnel Studies of the Hypersonic Flowfield around the Hypervelocity Ballistic Models with Aerospikes

    NASA Astrophysics Data System (ADS)

    Balakalyani, G.; Saravanan, S.; Jagadeesh, G.

    Reduced drag and aerodynamic heating are the two basic design requirements for any hypersonic vehicle [1]. The flowfield around an axisymmetric blunt body is characterized by a bow shockwave standing ahead of its nose. The pressure and temperature behind this shock wave are very high. This increased pressure and temperature are responsible for the high levels of drag and aerodynamic heating over the body. In the past, there have been many investigations on the use of aerospikes as a drag reduction tool. These studies on spiked bodies aim at reducing both the drag and aerodynamic heating by modifying the hypersonic flowfield ahead of the nose of the body [2]. However, most of them used very simple configurations to experimentally study the drag reduction using spikes at hypersonic speeds [3] and therefore very little experimental data is available for a realistic geometric configuration. In the present study, the standard AGARD Hypervelocity Ballistic model 1 is used as the test model. The addition of the spike to the blunt body significantly alters the flowfield ahead of the nose, leading to the formation of a low pressure conical recirculation region, thus causing a reduction in drag and wall heat flux [4]. In the present investigation, aerodynamic drag force is measured over the Hypervelocity Ballistic model-1, with and without spike, at a flow enthalpy of 1.7 MJ/kg. The experiments are carried out at a Mach number of 8 and at zero angle of attack. An internally mountable accelerometer based 3-component force balance system is used to measure the aerodynamic forces on the model. Also computational studies are carried out to complement the experiments.

  20. Macroscopic electric charge separation during hypervelocity impacts: Potential implications for planetary paleomagnetism

    NASA Technical Reports Server (NTRS)

    Crawford, D. A.; Schultz, P. H.

    1993-01-01

    The production of transient magnetic fields by hypervelocity meteoroid impact has been proposed to possibly explain the presence of paleomagnetic fields in certain lunar samples as well as across broader areas of the lunar surface. In an effort to understand the lunar magnetic record, continued experiments at the NASA Ames Vertical Gun Range allow characterizing magnetic fields produced by the 5 km/s impacts of 0.32-0.64 cm projectiles over a broad range of impact angles and projectile/target compositions. From such studies, another phenomenon has emerged, macroscopic electric charge separation, that may have importance for the magnetic state of solid-body surfaces. This phenomenon was observed during explosive cratering experiments, but the magnetic consequences of macroscopic electric charge separation (as opposed to plasma production) during explosion and impact cratering have not, to our knowledge, been explored before now. It is straightforward to show that magnetic field production due to this process may scale as a weakly increasing function of impactor kinetic energy, although more work is needed to precisely assess the scaling dependence. The original intent of our experiments was to assess the character of purely electrostatic signals for comparison with inferred electrostatic noise signals acquired by shielded magnetic sensors buried within particulate dolomite targets. The results demonstrated that electrostatic noise does affect the magnetic sensors but only at relatively short distances (less than 4 cm) from the impact point (our magnetic studies are generally performed at distances greater than approximately 5.5 cm). However, to assess models for magnetic field generation during impact, measurements are needed of the magnetic field as close to the impact point as possible; hence, work with an improved magnetic sensor design is in progress. In this paper, we focus on electric charge separation during hypervelocity impacts as a potential transient

  1. Time Resolved Temperature Measurement of Hypervelocity Impact Generated Plasma Using a Global Optimization Method

    NASA Astrophysics Data System (ADS)

    Hew, Y. M.; Linscott, I.; Close, S.

    2015-12-01

    Meteoroids and orbital debris, collectively referred to as hypervelocity impactors, travel between 7 and 72 km/s in free space. Upon their impact onto the spacecraft, the energy conversion from kinetic to ionization/vaporization occurs within a very brief timescale and results in a small and dense expanding plasma with a very strong optical flash. The radio frequency (RF) emission produced by this plasma can potentially lead to electrical anomalies within the spacecraft. In addition, space weather, such as solar activity and background plasma, can establish spacecraft conditions which can exaggerate the damages done by these impacts. During the impact, a very strong impact flash will be generated. Through the studying of this emission spectrum of the impact, we hope to study the impact generated gas cloud/plasma properties. The impact flash emitted from a ground-based hypervelocity impact test is long expected by many scientists to contain the characteristics of the impact generated plasma, such as plasma temperature and density. This paper presents a method for the time-resolved plasma temperature estimation using three-color visible band photometry data with a global pattern search optimization method. The equilibrium temperature of the plasma can be estimated using an optical model which accounts for both the line emission and continuum emission from the plasma. Using a global pattern search based optimizer, the model can isolate the contribution of the continuum emission versus the line emission from the plasma. The plasma temperature can thus be estimated. Prior to the optimization step, a Gaussian process is also applied to extract the optical emission signal out of the noisy background. The resultant temperature and line-to-continuum emission weighting factor are consistent with the spectrum of the impactor material and current literature.

  2. Prewhirl Jet Model

    NASA Technical Reports Server (NTRS)

    Meng, S. Y.; Jensen, M.; Jackson, E. D.

    1985-01-01

    Simple accurate model of centrifugal or rocket engine pumps provides information necessary to design inducer backflow deflector, backflow eliminator and prewhirl jet in jet mixing zones. Jet design based on this model shows improvement in inducer suction performance and reduced cavitation damage.

  3. Risk factors of jet fuel combustion products.

    PubMed

    Tesseraux, Irene

    2004-04-01

    Air travel is increasing and airports are being newly built or enlarged. Concern is rising about the exposure to toxic combustion products in the population living in the vicinity of large airports. Jet fuels are well characterized regarding their physical and chemical properties. Health effects of fuel vapors and liquid fuel are described after occupational exposure and in animal studies. Rather less is known about combustion products of jet fuels and exposure to those. Aircraft emissions vary with the engine type, the engine load and the fuel. Among jet aircrafts there are differences between civil and military jet engines and their fuels. Combustion of jet fuel results in CO2, H2O, CO, C, NOx, particles and a great number of organic compounds. Among the emitted hydrocarbons (HCs), no compound (indicator) characteristic for jet engines could be detected so far. Jet engines do not seem to be a source of halogenated compounds or heavy metals. They contain, however, various toxicologically relevant compounds including carcinogenic substances. A comparison between organic compounds in the emissions of jet engines and diesel vehicle engines revealed no major differences in the composition. Risk factors of jet engine fuel exhaust can only be named in context of exposure data. Using available monitoring data, the possibilities and limitations for a risk assessment approach for the population living around large airports are presented. The analysis of such data shows that there is an impact on the air quality of the adjacent communities, but this impact does not result in levels higher than those in a typical urban environment. PMID:15093276

  4. Reusable Metallic Thermal Protection Systems Development

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.; Martin, Carl J.; Daryabeigi, Kamran; Poteet, Carl C.

    1998-01-01

    Metallic thermal protection systems (TPS) are being developed to help meet the ambitious goals of future reusable launch vehicles. Recent metallic TPS development efforts at NASA Langley Research Center are described. Foil-gage metallic honeycomb coupons, representative of the outer surface of metallic TPS were subjected to low speed impact, hypervelocity impact, rain erosion, and subsequent arcjet exposure. TPS panels were subjected to thermal vacuum, acoustic, and hot gas flow testing. Results of the coupon and panel tests are presented. Experimental and analytical tools are being developed to characterize and improve internal insulations. Masses of metallic TPS and advanced ceramic tile and blanket TPS concepts are compared for a wide range of parameters.

  5. Structural Damage Prediction and Analysis for Hypervelocity Impact: Properties of Largest Fragment Produced by Hypervelocity Impact of Aluminum Spheres with Thin Aluminum Sheets

    NASA Technical Reports Server (NTRS)

    Piekutowski, Andrew J.

    1995-01-01

    Results of a series of hypervelocity impact tests are presented. In these tests, 1.275-g, 9.53-mm-diameter, 2017-T4 aluminum spheres were fired at normal incidence at eight thicknesses of 6061-T6 aluminum sheet. Bumper thickness to projectile diameter (t/D) ratio ranged from 0.026 to 0.424. Nominal impact velocity was 6.7 km/s. Results of five tests using 6.35, 9.53, and 12.70-mm-diameter aluminum spheres and other aluminum alloy bumpers are also given. A large chunky fragment of projectile was observed at the center of the debris clouds produced by the impacts. The equivalent diameter of this large fragment ranged from 5.5 mm for the lowest t/D ratio to a minimum of 0.6 mm for the case where maximum breakup of the projectile occurred (t/D approximately 0.2 to 0.3). When the t/D ratio was 0.42, numerous large flaky fragments were evenly distributed in the external bubble of bumper debris. Velocity of the large central fragments decreased continuously with increasing t/D ratio, ranging from about 99 percent to less than 80 percent of the impact velocity. The change in the velocity of small fragments spalling from the rear of the projectile was used to obtain a relationship showing a linear increase in the size of the central projectile fragment with decrease in the shock-induced stress in the projectile.

  6. Extension and Validation of a Hybrid Particle-Finite Element Method for Hypervelocity Impact Simulation. Chapter 2

    NASA Technical Reports Server (NTRS)

    Fahrenthold, Eric P.; Shivarama, Ravishankar

    2004-01-01

    The hybrid particle-finite element method of Fahrenthold and Horban, developed for the simulation of hypervelocity impact problems, has been extended to include new formulations of the particle-element kinematics, additional constitutive models, and an improved numerical implementation. The extended formulation has been validated in three dimensional simulations of published impact experiments. The test cases demonstrate good agreement with experiment, good parallel speedup, and numerical convergence of the simulation results.

  7. Aeroacoustics of hot jets

    NASA Astrophysics Data System (ADS)

    Viswanathan, K.

    2004-10-01

    A systematic study has been undertaken to quantify the effect of jet temperature on the noise radiated by subsonic jets. Nozzles of different diameters were tested to uncover the effects of Reynolds number. All the tests were carried out at Boeing's Low Speed Aeroacoustic Facility, with simultaneous measurement of thrust and noise. It is concluded that the change in spectral shape at high jet temperatures, normally attributed to the contribution from dipoles, is due to Reynolds number effects and not dipoles. This effect has not been identified before. A critical value of the Reynolds number that would need to be maintained to avoid the effects associated with low Reynolds number has been estimated to be {˜}400 000. It is well-known that large-scale structures are the dominant generators of noise in the peak radiation direction for high-speed jets. Experimental evidence is presented that shows the spectral shape at angles close to the jet axis from unheated low subsonic jets to be the same as from heated supersonic jets. A possible mechanism for the observed trend is proposed. When a subsonic jet is heated with the Mach number held constant, there is a broadening of the angular sector in which peak radiation occurs. Furthermore, there is a broadening of the spectral peak. Similar trends have been observed at supersonic Mach numbers. The spectral shapes in the forward quadrant and in the near-normal angles from unheated and heated subsonic jets also conform to the universal shape obtained from supersonic jet data. Just as for unheated jets, the peak frequency at angles close to the jet axis is independent of jet velocity as long as the acoustic Mach number is less than unity. The extensive database generated in the current test programme is intended to provide test cases with high-quality data that could be used for the evaluation of theoretical/semi-theoretical jet noise prediction methodologies.

  8. Theory of laminar viscous jets

    NASA Astrophysics Data System (ADS)

    Martynenko, O. G.; Korovkin, V. N.; Sokovishin, Iu. A.

    Results of recent theoretical studies of laminar jet flows of a viscous incompressible fluid are reviewed. In particular, attention is given to plane, fan-shaped, axisymmetric, and swirling jet flows; jet flows behind bodies; and slipstream jet flows. The discussion also covers dissipation of mechanical energy in jet flows, jet flows with a zero excess momentum, and asymptotic series expansions in the theory of jet flows.

  9. Jet Substructure Without Trees

    SciTech Connect

    Jankowiak, Martin; Larkoski, Andrew J.; /SLAC /Stanford U., ITP

    2011-08-19

    We present an alternative approach to identifying and characterizing jet substructure. An angular correlation function is introduced that can be used to extract angular and mass scales within a jet without reference to a clustering algorithm. This procedure gives rise to a number of useful jet observables. As an application, we construct a top quark tagging algorithm that is competitive with existing methods. In preparation for the LHC, the past several years have seen extensive work on various aspects of collider searches. With the excellent resolution of the ATLAS and CMS detectors as a catalyst, one area that has undergone significant development is jet substructure physics. The use of jet substructure techniques, which probe the fine-grained details of how energy is distributed in jets, has two broad goals. First, measuring more than just the bulk properties of jets allows for additional probes of QCD. For example, jet substructure measurements can be compared against precision perturbative QCD calculations or used to tune Monte Carlo event generators. Second, jet substructure allows for additional handles in event discrimination. These handles could play an important role at the LHC in discriminating between signal and background events in a wide variety of particle searches. For example, Monte Carlo studies indicate that jet substructure techniques allow for efficient reconstruction of boosted heavy objects such as the W{sup {+-}} and Z{sup 0} gauge bosons, the top quark, and the Higgs boson.

  10. CALCULATIONS FOR A MERCURY JET TARGET IN A SOLENOID MAGNET CAPTURE SYSTEM.

    SciTech Connect

    GALLARDO, J.; KAHN, S.; PALMER, R.B.; THIEBERGER, P.; WEGGEL, R.J.; MCDONALD, K.

    2001-06-18

    A mercury jet is being considered as the production target for a muon storage ring facility to produce an intense neutrino beam. A 20 T solenoid magnet that captures pions for muon production surrounds the mercury target. As the liquid metal jet enters or exits the field eddy currents are induced. We calculate the effects that a liquid metal jet experiences in entering and exiting the magnetic field for the magnetic configuration considered in the Neutrino Factory Feasibility Study II.

  11. Ejection and Lofting of Dust from Hypervelocity Impacts on the Moon

    NASA Astrophysics Data System (ADS)

    Hermalyn, B.; Schultz, P. H.

    2011-12-01

    Hypervelocity impact events mobilize and redistribute fine-grained regolith dust across the surfaces of planetary bodies. The ejecta mass-velocity distribution controls the location and emplacement of these materials. The current flux of material falling on the moon is dominated by small bolides and should cause frequent impacts that eject dust at high speeds. For example, approximately 25 LCROSS-sized (~20-30m diameter) craters are statistically expected to be formed naturally on the moon during any given earth year. When scaled to lunar conditions, the high-speed component of ejecta from hypervelocity impacts can be lofted for significant periods of time (as evidenced by the LCROSS mission results, c.f., Schultz, et al., 2010, Colaprete, et al., 2010). Even at laboratory scales, ejecta can approach orbital velocities; the higher impact speeds and larger projectiles bombarding the lunar surface may permit a significant portion of material to be launched closer to escape velocity. When these ejecta return to the surface (or encounter local topography), they impact at hundreds of meters per second or faster, thereby "scouring" the surface with low mass oblique impacts. While these high-speed ejecta represent only a small fraction of the total ejected mass, the lofting and subsequent ballistic return of this dust has the highest mobilization potential and will be directly applicable to the upcoming LADEE mission. A suite of hypervelocity impact experiments into granular materials was performed at the NASA Ames Vertical Gun Range (AVGR). This study incorporates both canonical sand targets and air-fall pumice dust to simulate the mechanical properties of lunar regolith. The implementation of a Particle Tracking Velocimetry (PTV) technique permits non-intrusive measurement of the ejecta velocity distribution within the ejecta curtain by following the path of individual ejecta particles. The PTV system developed at the AVGR uses a series of high-speed cameras (ranging

  12. Recording and investigation of the seismic signal generated by hypervelocity impact experiments and numerical models

    NASA Astrophysics Data System (ADS)

    Güldemeister, N.; Moser, D.; Wünnemann, K.; Hoerth, T.; Schäfer, F.

    2013-09-01

    Meteorite impacts can cause environmental consequences, one of which is the generation of ground motions that may exceed the magnitude of the largest earthquakes [1]. Impacts generate shock waves that attenuate with distance until they even tually turn into seismic waves. Thus, meteorite impact may be considered as a source for seismic shaking similar to earthquakes. Seismic signals have been recorded in explosion experiments [2] and in hydrocode models of large impact events such as the Chicxulub crater [3]. To determine how much of the kinetic energy Ekin of the impactoris turned into seismic energy Eseis can be investigated experimentally (by recording the acoustic emission) or by numerical models. The ratio of Eseis/Ekin is the so called seismic efficiency k. The seismic efficiency depends on material properties (porosity) and is usually estimated to range between 10-2 and 10-6 [2,4]. In the framework of the "MEMIN" (multidisciplinary experimental and modeling impact crater research network) project a suite of hypervelocity impact experiments on a decimeter scale have been carried out [5]. We use acoustic emission (AE) technique and pressure gauges in high spatiotemporal Meteorite impacts can cause environmental consequences, one of which is the generation of ground motions that may exceed the magnitude of the largest earthquakes [1]. Impacts generate shock waves that attenuate with distance until they even tually turn into seismic waves. Thus, meteorite impact may be considered as a source for seismic shaking similar to earthquakes. Seismic signals have been recorded in explosion experiments [2] and in hydrocode models of large impact events such as the Chicxulub crater [3]. To determine how much of the kinetic energy Ekin of the impactoris turned into seismic energy Eseis can be investigated experimentally (by recording the acoustic emission) or by numerical models. The ratio of Eseis/Ekin is the so called seismic efficiency k. The seismic efficiency depends

  13. Jets from young stars

    NASA Astrophysics Data System (ADS)

    Bally, John

    2007-10-01

    Most stars produce spectacular jets during their formation. There are thousands of young stars within 500 pc of the Sun and many power jets. Thus protostellar jets may be the most common type of collimated astrophysical outflow. Shocks powered by outflows excite many emission lines, exhibit a rich variety of structure, and motions with velocities ranging from 50 to over 500 km s-1. Due to their relative proximity, proper motions and structural changes can be observed in less than a year. I review the general properties of protostellar jets, summarize some results from recent narrow-band imaging surveys of entire clouds, discuss irradiated jets, and end with some comments concerning outflows from high-mass young stellar objects. Protostellar outflows are ideal laboratories for the exploration of the jet physics.

  14. Relativistic Jets in Collapsars

    NASA Astrophysics Data System (ADS)

    Zhang, Weiqun; Woosley, S. E.; MacFadyen, A. I.

    2003-04-01

    We examine the propagation of two-dimensional relativistic jets through the stellar progenitor in the collapsar model for gamma-ray bursts. In agreement with previous studies, we find that the jet is collimated by its passage. Moreover, interaction of the jet with the star causes mixing that sporadically decelerates the jet, leading to a highly variable Lorentz factor. The jet that finally emerges has a moderate Lorentz factor, but a very large internal energy loading. In a second series of calculations we follow the emergence of such enegy-loaded jets from the star. For the initial conditions chosen, conversion of the remaining internal energy gives a terminal Lorentz factor of approximately 150. Implications of our calculations for GRB light curves, the luminosity-variability relation, and the GRB-supernova association are discussed.

  15. What ignites optical jets?

    SciTech Connect

    Sebastian Jester

    2002-12-23

    The properties of radio galaxies and quasars with and without optical or X-ray jets are compared. The majority of jets from which high-frequency emission has been detected so far (13 with optical emission, 11 with X-rays, 13 with both) are associated with the most powerful radio sources at any given redshift. It is found that optical/X-ray jet sources are more strongly beamed than the average population of extragalactic radio sources. This suggests that the detection or non-detection of optical emission from jets has so far been dominated by surface brightness selection effects, not by jet physics. It implies that optical jets are much more common than is currently appreciated.

  16. Cavitation Inception in Immersed Jet Shear Flows

    NASA Astrophysics Data System (ADS)

    Lockett, R. D.; Ndamuso, N.; Price, R.

    2015-12-01

    Cavitation inception occurring in immersed jets was investigated in a purpose-built mechanical flow rig. The rig utilized custom-built cylindrical and conical nozzles to direct high-velocity jets of variable concentration n-octane-hexadecane mixtures into a fused silica optically accessible receiver. The fluid pressure upstream and down-stream of the nozzles were manually controlled. The study employed a variety of acrylic and metal nozzles. The results show that the critical upstream pressure to downstream pressure ratio for incipient cavitation decreases with increasing n-octane concentration for the cylindrical nozzles, and increases with increasing n-octane concentration for the conical nozzle.

  17. Properties of gluon jets

    SciTech Connect

    Sugano, K.

    1986-09-01

    The properties of gluon jets are reviewed from an experimental point of view. The measured characteristics are compared to theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, there are remarkable agreements and also intriguing disagreements between experiment and theory. Since much interesting data have begun to emerge from various experiments and the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on our understanding of QCD. Finally, the future prospects are discussed.

  18. Perspectives on jet noise

    NASA Technical Reports Server (NTRS)

    Ribner, H. S.

    1981-01-01

    Jet noise is a byproduct of turbulence. Until recently turbulence was assumed to be known statistically, and jet noise was computed therefrom. As a result of new findings though on the behavior of vortices and instability waves, a more integrated view of the problem has been accepted lately. After presenting a simple view of jet noise, the paper attempts to resolve the apparent differences between Lighthill's and Lilley's interpretations of mean-flow shear, and examines a number of ad hoc approaches to jet noise suppression.

  19. Interpretation of extragalactic jets

    SciTech Connect

    Norman, M.L.

    1985-01-01

    The nature of extragalatic radio jets is modeled. The basic hypothesis of these models is that extragalatic jets are outflows of matter which can be described within the framework of fluid dynamics and that the outflows are essentially continuous. The discussion is limited to the interpretation of large-scale (i.e., kiloparsec-scale) jets. The central problem is to infer the physical parameters of the jets from observed distributions of total and polarized intensity and angle of polarization as a function of frequency. 60 refs., 6 figs.

  20. SUPERNOVAE IN THE CENTRAL PARSEC: A MECHANISM FOR PRODUCING SPATIALLY ANISOTROPIC HYPERVELOCITY STARS

    SciTech Connect

    Zubovas, Kastytis; Wynn, Graham A.; Gualandris, Alessia

    2013-07-10

    Several tens of hypervelocity stars (HVSs) have been discovered escaping our Galaxy. These stars share a common origin in the Galactic center and are distributed anisotropically in Galactic longitude and latitude. We examine the possibility that HVSs may be created as the result of supernovae (SNe) occurring within binary systems in a disk of stars around Sgr A* over the last 100 Myr. Monte Carlo simulations show that the rate of binary disruption is {approx}10{sup -4} yr{sup -1}, comparable to that of tidal disruption models. The SN-induced HVS production rate ({Gamma}{sub HVS}) is significantly increased if the binaries are hardened via migration through a gaseous disk. Moderate hardening gives {Gamma}{sub HVS} {approx_equal} 2 Multiplication-Sign 10{sup -7} yr{sup -1} and an estimated population of {approx}20 HVSs in the last 100 Myr. SN-induced HVS production requires the internal and external orbital velocity vectors of the secondary binary component to be aligned when the binary is disrupted. This leaves an imprint of the disk geometry on the spatial distribution of the HVSs, producing a distinct anisotropy.

  1. Continued Development of a Global Heat Transfer Measurement System at AEDC Hypervelocity Wind Tunnel 9

    NASA Technical Reports Server (NTRS)

    Kurits, Inna; Lewis, M. J.; Hamner, M. P.; Norris, Joseph D.

    2007-01-01

    Heat transfer rates are an extremely important consideration in the design of hypersonic vehicles such as atmospheric reentry vehicles. This paper describes the development of a data reduction methodology to evaluate global heat transfer rates using surface temperature-time histories measured with the temperature sensitive paint (TSP) system at AEDC Hypervelocity Wind Tunnel 9. As a part of this development effort, a scale model of the NASA Crew Exploration Vehicle (CEV) was painted with TSP and multiple sequences of high resolution images were acquired during a five run test program. Heat transfer calculation from TSP data in Tunnel 9 is challenging due to relatively long run times, high Reynolds number environment and the desire to utilize typical stainless steel wind tunnel models used for force and moment testing. An approach to reduce TSP data into convective heat flux was developed, taking into consideration the conditions listed above. Surface temperatures from high quality quantitative global temperature maps acquired with the TSP system were then used as an input into the algorithm. Preliminary comparison of the heat flux calculated using the TSP surface temperature data with the value calculated using the standard thermocouple data is reported.

  2. Scaling of heat transfer augmentation due to mechanical distortions in hypervelocity boundary layers

    NASA Astrophysics Data System (ADS)

    Flaherty, W.; Austin, J. M.

    2013-10-01

    We examine the response of hypervelocity boundary layers to global mechanical distortions due to concave surface curvature. Surface heat transfer and visual boundary layer thickness data are obtained for a suite of models with different concave surface geometries. Results are compared to predictions using existing approximate methods. Near the leading edge, good agreement is observed, but at larger pressure gradients, predictions diverge significantly from the experimental data. Up to a factor of five underprediction is reported in regions with greatest distortion. Curve fits to the experimental data are compared with surface equations. We demonstrate that reasonable estimates of the laminar heat flux augmentation may be obtained as a function of the local turning angle for all model geometries, even at the conditions of greatest distortion. This scaling may be explained by the application of Lees similarity. As a means of introducing additional local distortions, vortex generators are used to impose streamwise structures into the boundary layer. The response of the large scale vortices to an adverse pressure gradient is investigated. Surface streak evolution is visualized over the different surface geometries using fast response pressure sensitive paint. For a flat plate baseline case, heat transfer augmentation at similar levels to turbulent flow is measured. For the concave geometries, increases in heat transfer by factors up to 2.6 are measured over the laminar values. The scaling of heat transfer with turning angle that is identified for the laminar boundary layer response is found to be robust even in the presence of the imposed vortex structures.

  3. Hypervelocity impact testing of advanced materials and structures for micrometeoroid and orbital debris shielding

    NASA Astrophysics Data System (ADS)

    Ryan, Shannon; Christiansen, Eric L.

    2013-02-01

    A series of 66 hypervelocity impact experiments have been performed to assess the potential of various materials (aluminium, titanium, copper, stainless steel, nickel, nickel/chromium, reticulated vitreous carbon, silver, ceramic, aramid, ceramic glass, and carbon fibre) and structures (monolithic plates, open-cell foam, flexible fabrics, rigid meshes) for micrometeoroid and orbital debris (MMOD) shielding. Arranged in various single-, double-, and triple-bumper configurations, screening tests were performed with 0.3175 cm diameter Al2017-T4 spherical projectiles at nominally 6.8 km/s and normal incidence. The top performing shields were identified through target damage assessments and their respective weight. The top performing candidate shield at the screening test condition was found to be a double-bumper configuration with a 0.25 mm thick Al3003 outer bumper, 6.35 mm thick 40 PPI aluminium foam inner bumper, and 1.016 mm thick Al2024-T3 rear wall (equal spacing between bumpers and rear wall). In general, double-bumper candidates with aluminium plate outer bumpers and foam inner bumpers were consistently found to be amongst the top performers. For this impact condition, potential weight savings of at least 47% over conventional all-aluminium Whipple shields are possible by utilizing the investigated materials and structures. The results of this study identify materials and structures of interest for further, more in-depth, impact investigations.

  4. Aerothermal Performance Constraints for Small Radius Leading Edges Operating at Hypervelocity

    NASA Technical Reports Server (NTRS)

    Kolodziej, Paul; Bull, Jeffrey D.; Milos, Frank S.; Squire, Thomas H.

    1997-01-01

    Small radius leading edges and nosetips were used to minimize wave drag in early hypervelocity vehicle concepts until further analysis demonstrated that extreme aerothermodynamic heating blunted the available thermal protection system materials. Recent studies indicate that ultra-high temperature composite (UHTC) materials are shape stable at temperatures approaching 3033 K and will be available for use as sharp leading edge components in the near future. Steady-state aerothermal performance constraints for UHTC components are presented in this paper to identify their non-ablating operational capability at altitudes from sea level to 90 km. An integrated design tool was developed to estimate these constraints. The tool couples aerothermodynamic heating with material response using commercial finite element analysis software and is capable of both steady-state and transient analysis. Performance during entry is analyzed by transient thermal analysis along the trajectory. The thermal load condition from the transient thermal analysis is used to estimate thermal stress. Applying the tool to UHTC materials shows that steady-state, non-ablating operation of a HfB2/SiC(A-7) (A-7) component is possible at velocities approaching Earth's circular orbital velocity of 7.9 km/s at altitudes approaching 70 km.

  5. New experimental capability to investigate the hypervelocity micrometeoroid bombardment of cryogenic surfaces

    NASA Astrophysics Data System (ADS)

    Nelson, Andrew Oakleigh; Dee, Richard; Gudipati, Murthy S.; Horányi, Mihály; James, David; Kempf, Sascha; Munsat, Tobin; Sternovsky, Zoltán; Ulibarri, Zach

    2016-02-01

    Ice is prevalent throughout the solar system and beyond. Though the evolution of many of these icy surfaces is highly dependent on associated micrometeoroid impact phenomena, experimental investigation of these impacts has been extremely limited, especially at the impactor speeds encountered in space. The dust accelerator facility at the Institute for Modeling Plasmas, Atmospheres, and Cosmic Dust (IMPACT) of NASA's Solar System Exploration Research Virtual Institute has developed a novel cryogenic system that will facilitate future study of hypervelocity impacts into ice and icy regolith. The target consists of a copper block, cooled by liquid nitrogen, upon which layers of vapor-deposited ice, pre-frozen ice, or icy regolith can be built in a controlled and quantifiable environment. This ice can be grown from a variety of materials, including H2O, CH3OH, NH3, and slurries containing nanophase iron. Ice temperatures can be varied between 96 K and 150 K and ice thickness greater than 150 nm can be accurately measured. Importantly, the composition of ion plumes created during micrometeoroid impacts onto these icy layers can be measured even in trace amounts by in situ time-of-flight mass spectroscopy. In this paper, we present the fundamental design components of the cryogenic target chamber at IMPACT and proof-of-concept results from target development and from first impacts into thick layers of water ice.

  6. Laminar heat-transfer distributions on biconics at incidence in hypersonic-hypervelocity flows

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III; Micol, J. R.; Gnoffo, P. A.

    1984-01-01

    Laminar heating distributions were measured at hypersonic-hypervelocity flow conditions on a 1.9-percent-scale model of an aeroassisted vehiclee proposed for missions to a number of planets. This vehicle is a spherically blunted, 12.84/7deg biconic with the fore-cone axis bent upward 7 deg relative to the aft-cone axis to provide selftrim capability. Also tested was a straight biconic (i.e., without nose bend) with the same nose radius and half-angles as the bent-nose biconic. These measurements were made in the Langley Expansion Tube at free-stream velocities from 4.5 to 6.9 km/sec and Mach numbers from 6.0 to 9.0 with helium, nitrogen, air, and carbon dioxide test gases. The range of calculated thermochemical equilibrium normal-shock density ratios for these four test gases was 4 to 19. Angles of attack, referenced to the aft-cone, varied from 0 to 20 deg. Heating distributions predicted with a parabolized Navier-Stokes (PNS) code were compared with measurement for helium and air test gases. Measured windward and leeward heating levels were generally underpredicted by the PNS code for both test gases, and agreement was poorer on the leeward side than on the windward side.

  7. Hypervelocity launching of flyers at the SG-III prototype laser facility

    NASA Astrophysics Data System (ADS)

    Shui, Min; Chu, Genbai; Zhu, Bin; He, Weihua; Xi, Tao; Fan, Wei; Xin, Jianting; Gu, Yuqiu

    2016-01-01

    Experiments of laser-driven hypervelocity flyers have been conducted at the SG-III prototype laser facility. Using the continuum phase plate technique, four laser beams each with a 3-ns quadratic profile are configured to produce relatively uniform irradiated spots of diameter size either 500 μm or 2000 μm. With the former, specifically designed multi-layered flyers (polyimide/copper) were accelerated by shock impedance and reverberation techniques via direct laser ablation to a super-high averaged velocity of 55 km/s, much faster than recently reported results. Light-emission signals of shock breakout and flyer impact on flat or stepped windows were obtained that indicated good planarity and integrity for the flyer. In the latter, single-layered aluminum flyers were gradually accelerated to a terminal velocity of 11 km/s, as measured by optical velocimetry, without melting and vaporization. The results suggest that the SG-III prototype laser facility has the capability to launch high-speed flyers to create extreme conditions for investigating the science of shock compression and its equation of state.

  8. Conceptual Design of a Flight Validation Mission for a Hypervelocity Asteroid Intercept Vehicle

    NASA Technical Reports Server (NTRS)

    Barbee, Brent W.; Wie, Bong; Steiner, Mark; Getzandanner, Kenneth

    2013-01-01

    Near-Earth Objects (NEOs) are asteroids and comets whose orbits approach or cross Earth s orbit. NEOs have collided with our planet in the past, sometimes to devastating effect, and continue to do so today. Collisions with NEOs large enough to do significant damage to the ground are fortunately infrequent, but such events can occur at any time and we therefore need to develop and validate the techniques and technologies necessary to prevent the Earth impact of an incoming NEO. In this paper we provide background on the hazard posed to Earth by NEOs and present the results of a recent study performed by the NASA/Goddard Space Flight Center s Mission Design Lab (MDL) in collaboration with Iowa State University s Asteroid Deflection Research Center (ADRC) to design a flight validation mission for a Hypervelocity Asteroid Intercept Vehicle (HAIV) as part of a Phase 2 NASA Innovative Advanced Concepts (NIAC) research project. The HAIV is a two-body vehicle consisting of a leading kinetic impactor and trailing follower carrying a Nuclear Explosive Device (NED) payload. The HAIV detonates the NED inside the crater in the NEO s surface created by the lead kinetic impactor portion of the vehicle, effecting a powerful subsurface detonation to disrupt the NEO. For the flight validation mission, only a simple mass proxy for the NED is carried in the HAIV. Ongoing and future research topics are discussed following the presentation of the detailed flight validation mission design results produced in the MDL.

  9. Conceptual design of a flight validation mission for a Hypervelocity Asteroid Intercept Vehicle

    NASA Astrophysics Data System (ADS)

    Barbee, Brent W.; Wie, Bong; Steiner, Mark; Getzandanner, Kenneth

    2015-01-01

    Near-Earth Objects (NEOs) are asteroids and comets whose orbits approach or cross Earth's orbit. NEOs have collided with our planet in the past, sometimes to devastating effect, and continue to do so today. Collisions with NEOs large enough to do significant damage to the ground are fortunately infrequent, but such events can occur at any time and we therefore need to develop and validate the techniques and technologies necessary to prevent the Earth impact of an incoming NEO. In this paper we provide background on the hazard posed to Earth by NEOs and present the results of a recent study performed by the NASA/Goddard Space Flight Center's Mission Design Lab (MDL) in collaboration with Iowa State University's Asteroid Deflection Research Center (ADRC) to design a flight validation mission for a Hypervelocity Asteroid Intercept Vehicle (HAIV) as part of a Phase 2 NASA Innovative Advanced Concepts (NIAC) research project. The HAIV is a two-body vehicle consisting of a leading kinetic impactor and trailing follower carrying a Nuclear Explosive Device (NED) payload. The HAIV detonates the NED inside the crater in the NEO's surface created by the lead kinetic impactor portion of the vehicle, effecting a powerful subsurface detonation to disrupt the NEO. For the flight validation mission, only a simple mass proxy for the NED is carried in the HAIV. Ongoing and future research topics are discussed following the presentation of the detailed flight validation mission design results produced in the MDL.

  10. A comparative analysis of the performance of long-range hypervelocity vehicles

    NASA Technical Reports Server (NTRS)

    Eggers, Alfred J , Jr; Allen, H Julian; Neice, Stanford E

    1955-01-01

    Long-range hypervelocity vehicles are studied in terms of their motion in powered flight, and their motion and aerodynamic heating in unpowered flight. Powered flight is analyzed for an idealized propulsion system which rather closely approaches present-day rocket motors. Unpowered flight is characterized by a return to earth along a ballistic, skip, or glide trajectory. Only those trajectories are treated which yield the maximum range for a given velocity at the end of powered flight. Aerodynamic heating is treated in a manner similar to that employed previously by the senior authors is studying ballistic missiles (NACA RM A53D28), with the exception that radiant as well as convective heat transfer is considered in connection with glide and skip vehicles. The ballistic vehicle is found to be the least efficient of the several types studied in the sense that it generally requires the highest velocity at the end of powered flight in order to attain a given range. This disadvantage may be offset, however, by reducing convective heat transfer to the re-entry body through the artifice of increasing pressure drag in relation to friction drag - that is, by using a blunt body. Thus the kinetic energy required by the vehicle at the end of powered flight may be reduced by minimizing the mass of coolant material involved.

  11. Extending the Applicable Range of the SRL Ballistic Limit Equation to Oblique Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Rudolph, Martin; Welty, Nathan; Putzar, Robin; Schafer, Frank; Koebel, David; Scheper, Marc; Janovsky, Rolf; Apeldoorn, Jeffrey; Lambert, Michel

    2012-07-01

    A standard method to assess the risk posed upon space assets from the micrometeoroid and space debris (MM/SD) environment is to evaluate the probability of no penetration (PNP) of the spacecraft outer hull. It implies catastrophic spacecraft failure upon a single particle penetration through the spacecraft structure wall. The method is justified by its conservative approach, however may result in overly protected structure walls. A more accurate approach is possible with the Schäfer-Ryan-Lambert (SRL) ballistic limit equation (BLE). It takes into consideration the components’ individual capability to defeat particles without functional effect. The initial equation [1] is calibrated with some 90 hypervelocity impact tests on fuel and heat pipes, pressure vessels, electronic boxes, harness and batteries. The paper at hand publishes results obtained from another 40 impact tests on three vulnerable components, namely the harness, electronics boxes and fuel pipes, with focus on oblique impacts at 45° and 60°. The obtained data complements the initial data base and a recalibration and validation of the SRL equation for oblique impacts is achieved. Applications for the SRL equation in the domain of spacecraft MM/SD risk assessment as well as in the domain of survivability enhancement are discussed.

  12. Hypervelocity missile: Based on the concept of aircraft/missile integration for maximum firepower

    NASA Astrophysics Data System (ADS)

    Aden, T. C.

    1983-08-01

    The conventional approach to weapons for the close air support/battlefield interdiction (CAS/BI) missions has not provided NATO forces with affordable, effective firepower of the order required to defeat armored thrusts. The conventional approach has led to weapons that are either too expensive for stockpile and training purposes or too expensive to go to war. It has also failed to provide NATO strike aircraft assigned to the CAS/BI missions with the ability to achieve a large number of kills per pass or kills per sortie. The hypervelocity missile concept integrates current and emerging flight control system (FCS) technology with a low cost, lightweight missile to provide NATO forces with a significant firepower improvement. The U.S. Air Force has completed a series of ground launched flight tests that have successfully resolved all technical issues critical to missile guidance, control and accuracy questions. This series of successful demonstrations permits immediate continuation into an air launch flight test environment to demonstrate the integration of the three critical elements -- the aircraft, the FCS, and the missile.

  13. THE NATURE OF HYPERVELOCITY STARS AND THE TIME BETWEEN THEIR FORMATION AND EJECTION

    SciTech Connect

    Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Cohen, Judith G. E-mail: mgeller@cfa.harvard.edu E-mail: jlc@astro.caltech.edu

    2012-07-20

    We obtain Keck HIRES spectroscopy of HVS5, one of the fastest unbound stars in the Milky Way halo. We show that HVS5 is a 3.62 {+-} 0.11 M{sub Sun} main-sequence B star at a distance of 50 {+-} 5 kpc. The difference between its age and its flight time from the Galactic center is 105 {+-} 18 (stat) {+-}30 (sys) Myr; flight times from locations elsewhere in the Galactic disk are similar. This 10{sup 8} yr 'arrival time' between formation and ejection is difficult to reconcile with any ejection scenario involving massive stars that live for only 10{sup 7} yr. For comparison, we derive arrival times of 10{sup 7} yr for two unbound runaway B stars, consistent with their disk origin where ejection results from a supernova in a binary system or dynamical interactions between massive stars in a dense star cluster. For HVS5, ejection during the first 10{sup 7} yr of its lifetime is ruled out at the 3{sigma} level. Together with the 10{sup 8} yr arrival times inferred for three other well-studied hypervelocity stars (HVSs), these results are consistent with a Galactic center origin for the HVSs. If the HVSs were indeed ejected by the central black hole, then the Galactic center was forming stars {approx_equal}200 Myr ago, and the progenitors of the HVSs took {approx_equal}100 Myr to enter the black hole's loss cone.

  14. A GALACTIC ORIGIN FOR HE 0437-5439, THE HYPERVELOCITY STAR NEAR THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Brown, Warren R.; Geller, Margaret J.; Kenyon, Scott J.; Anderson, Jay; Bond, Howard E.; Livio, Mario; Gnedin, Oleg Y. E-mail: mgeller@cfa.harvard.ed E-mail: jayander@stsci.ed E-mail: mlivio@stsci.ed

    2010-08-10

    We use Hubble Space Telescope imaging to measure the absolute proper motion of the hypervelocity star (HVS) HE 0437-5439, a short-lived B star located in the direction of the Large Magellanic Cloud (LMC). We observe ({mu}{sub {alpha}} {mu}{sub {delta}}) = (+0.53 {+-} 0.25(stat) {+-} 0.33(sys), + 0.09 {+-} 0.21(stat) {+-} 0.48(sys)) mas yr{sup -1}. The velocity vector points directly away from the center of the Milky Way; an origin from the center of the LMC is ruled out at the 3{sigma} level. The flight time of the HVS from the Milky Way exceeds its main-sequence lifetime, thus its stellar nature requires it to be a blue straggler. The large space velocity rules out a Galactic-disk ejection. Combining the HVS's observed trajectory, stellar nature, and required initial velocity, we conclude that HE 0437-5439 was most likely a compact binary ejected by the Milky Way's central black hole.

  15. Electrical signatures of hypervelocity impact plasma with applications in in-situ particle detection

    NASA Astrophysics Data System (ADS)

    Rudolph, M.; Schimmerohn, M.; Osterholz, J.; Schäfer, F.

    2014-08-01

    Hypervelocity impacts of micrometeoroid and space debris particles can produce a highly transient plasma cloud that shows a spectrum of distinct electrical phenomena ranging from charge production to electrostatic field and electromagnetic wave generation. The coupling of these effects to electrical probes can be used as a means of in-situ debris detection to monitor the polluted orbits around the Earth. In the past, some detectors were built mainly for the detection of natural dust populations in space, such as a long heritage of charge collection detectors. In addition, several radio astronomy and ambient plasma instruments that were not specifically dedicated to particle detection revealed impact-induced anomalies during interplanetary missions. Most of them were explained by the interaction of electrically sensitive probes with free charges produced upon impact. For the application in low Earth orbits, one needs to take into account, that the man-made debris population differs from natural populations in many regards, as does the plasma environment between interplanetary space and in orbits close to Earth. The paper at hand gives a summary of detectors with flight heritage and devises a first concept for in situ space debris detectors in low Earth orbit by exploiting past experience with dust detectors in deep space.

  16. Failure mechanism of monolayer graphene under hypervelocity impact of spherical projectile.

    PubMed

    Xia, Kang; Zhan, Haifei; Hu, De'an; Gu, Yuantong

    2016-01-01

    The excellent mechanical properties of graphene have enabled it as appealing candidate in the field of impact protection or protective shield. By considering a monolayer graphene membrane, in this work, we assessed its deformation mechanisms under hypervelocity impact (from 2 to 6 km/s), based on a serial of in silico studies. It is found that the cracks are formed preferentially in the zigzag directions which are consistent with that observed from tensile deformation. Specifically, the boundary condition is found to exert an obvious influence on the stress distribution and transmission during the impact process, which eventually influences the penetration energy and crack growth. For similar sample size, the circular shape graphene possesses the best impact resistance, followed by hexagonal graphene membrane. Moreover, it is found the failure shape of graphene membrane has a strong relationship with the initial kinetic energy of the projectile. The higher kinetic energy, the more number the cracks. This study provides a fundamental understanding of the deformation mechanisms of monolayer graphene under impact, which is crucial in order to facilitate their emerging future applications for impact protection, such as protective shield from orbital debris for spacecraft. PMID:27618989

  17. Panspermia Survival Scenarios for Organisms that Survive Typical Hypervelocity Solar System Impact Events.

    NASA Astrophysics Data System (ADS)

    Pasini, D.

    2014-04-01

    Previous experimental studies have demonstrated the survivability of living cells during hypervelocity impact events, testing the panspermia and litho-panspermia hypotheses [1]. It has been demonstrated by the authors that Nannochloropsis Oculata Phytoplankton, a eukaryotic photosynthesizing autotroph found in the 'euphotic zone' (sunlit surface layers of oceans [2]), survive impacts up to 6.93 km s-1 (approx. shock pressure 40 GPa) [3, 4]. Also shown to survive impacts up to 5.49 km s-1 is the tardigrade species Hypsibius dujardini (a complex micro-animal consisting of 40,000 cells) [5, 6]. It has also been shown that they can survive sustained pressures up to 600 MPa using a water filled pressure capsule [7]. Additionally bacteria can survive impacts up to 5.4 km s-1 (~30 GPa) - albeit with a low probability of survival [1], and the survivability of yeast spores in impacts up to 7.4 km s-1 (~30 GPa) has also recently been demonstrated [8]. Other groups have also reported that the lichen Xanthoria elegans is able to survive shocks in similar pressure ranges (~40 GPa) [9]. Here we present various simulated impact regimes to show which scenarios are condusive to the panspermia hypothesis of the natural transfer of life (via an icy body) through space to an extraterrestrial environment.

  18. Processing and Synthesis of Pre-Biotic Chemicals in Hypervelocity Impacts

    NASA Technical Reports Server (NTRS)

    Brickerhoff, W. B.; Managadze, G. G.; Chumikov, A. E.; Managadze, N. G.

    2005-01-01

    Hypervelocity impacts (HVIs) may have played a significant role in establishing the initial organic inventory for pre-biotic chemistry on the Earth and other planetary bodies. In addition to the delivery of organic compounds intact to planetary surfaces, generally at velocities below approx.20 km/s, HVIs also enable synthesis of new molecules. The cooling post-impact plasma plumes of HVIs in the interstellar medium (ISM), the protosolar nebula (PSN), and the early solar system comprise pervasive conditions for organic synthesis. Such plasma synthesis (PS) can operate over many length scales (from nm-scale dust to planets) and energy scales (from molecular rearrangement to atomization and recondensation). HVI experiments with the flexibility to probe the highest velocities and distinguish synthetic routes are a high priority to understand the relevance of PS to exobiology. We describe here recent studies of PS at small spatial scales and extremely high velocities with pulsed laser ablation (PLA). PLA can simulate the extreme plasma conditions generated in impacts of dust particles at speeds of up to 100 km/s or more. When applied to carbonaceous solids, new and pre-biotically relevant molecular species are formed with high efficiency [1,2].

  19. Chemical and thermal nonequilibrium heat transfer analysis for hypervelocity, low Reynolds number flow

    NASA Technical Reports Server (NTRS)

    Brown, K. G.

    1985-01-01

    Chemical and thermal nonequilibrium phenomena are studied in the stagnation region of a hypervelocity blunt body. This investigation is motivated by the need to predict the heat transfer rate to the leading edge of Aeromaneuvering Orbital Transfer Vehicles. Flight speeds of approximately 10 km/s at altitudes of approximately 80 km are considered for body radii of 1 to 50 cm. The analysis is based on continuum theory and is applicable to the viscous-layer and incipient-merged-layer rarefied-flow regimes. A two-species, two-temperature gas model is assumed. Comparisons are made with previous theories, experimental data, and results based on the thermodynamic equilibrium assumption. The equation accounting for vibrational nonequilibrium is presented and its effects on flow properties are discussed. Parameters which require further investigation are identified. Preliminary results indicate that the inclusion of vibrational relaxation has little effect on heat transfer rate for a catalytic surface. However, vibrational nonequilibrium may increase the heat transfer rate to a noncatalytic surface, depending on the degree of nonequilibrium.

  20. Chemical and Thermal Nonequilibrium Heat-Transfer Analysis for Hypervelocity, Low Reynolds Number Flow

    NASA Technical Reports Server (NTRS)

    Brown, Kevin G.

    1986-01-01

    Chemical and thermal nonequilibrium phenomena are studied in the stagnation region of a hypervelocity blunt body. This investigation is motivated by the need to predict the heat-transfer rate to the leading edge of aeromaneuvering orbital transfer vehicles. Flight speeds of approximately 10 km/s at altitudes of approximately 80 km are considered for body radii of 1-50 cm. The analysis is based on continuum theory and is applicable to the viscous and incipient merged layer regimes of rarefied flow. A two-species, two-temperature gas model is assumed. Comparisons are made with previous theories, experimental data, and results based on the thermodynamic equilibrium assumption. The equation accounting for vibrational nonequilibrium is presented and its effects on flow properties are discussed. Parameters requiring further investigation are identified. Preliminary results indicate that the inclusion of vibrational relaxation has little effect on the heat-transfer rate for a fully catalytic surface. However, vibrational nonequilibrium may increase the heat-transfer rate to a noncatalytic surface, depending on the degree of nonequilibrium.

  1. New experimental capability to investigate the hypervelocity micrometeoroid bombardment of cryogenic surfaces.

    PubMed

    Nelson, Andrew Oakleigh; Dee, Richard; Gudipati, Murthy S; Horányi, Mihály; James, David; Kempf, Sascha; Munsat, Tobin; Sternovsky, Zoltán; Ulibarri, Zach

    2016-02-01

    Ice is prevalent throughout the solar system and beyond. Though the evolution of many of these icy surfaces is highly dependent on associated micrometeoroid impact phenomena, experimental investigation of these impacts has been extremely limited, especially at the impactor speeds encountered in space. The dust accelerator facility at the Institute for Modeling Plasmas, Atmospheres, and Cosmic Dust (IMPACT) of NASA's Solar System Exploration Research Virtual Institute has developed a novel cryogenic system that will facilitate future study of hypervelocity impacts into ice and icy regolith. The target consists of a copper block, cooled by liquid nitrogen, upon which layers of vapor-deposited ice, pre-frozen ice, or icy regolith can be built in a controlled and quantifiable environment. This ice can be grown from a variety of materials, including H2O, CH3OH, NH3, and slurries containing nanophase iron. Ice temperatures can be varied between 96 K and 150 K and ice thickness greater than 150 nm can be accurately measured. Importantly, the composition of ion plumes created during micrometeoroid impacts onto these icy layers can be measured even in trace amounts by in situ time-of-flight mass spectroscopy. In this paper, we present the fundamental design components of the cryogenic target chamber at IMPACT and proof-of-concept results from target development and from first impacts into thick layers of water ice. PMID:26931872

  2. Hypervelocity Impact Test Fragment Modeling: Modifications to the Fragment Rotation Analysis and Lightcurve Code

    NASA Technical Reports Server (NTRS)

    Gouge, Michael F.

    2011-01-01

    Hypervelocity impact tests on test satellites are performed by members of the orbital debris scientific community in order to understand and typify the on-orbit collision breakup process. By analysis of these test satellite fragments, the fragment size and mass distributions are derived and incorporated into various orbital debris models. These same fragments are currently being put to new use using emerging technologies. Digital models of these fragments are created using a laser scanner. A group of computer programs referred to as the Fragment Rotation Analysis and Lightcurve code uses these digital representations in a multitude of ways that describe, measure, and model on-orbit fragments and fragment behavior. The Dynamic Rotation subroutine generates all of the possible reflected intensities from a scanned fragment as if it were observed to rotate dynamically while in orbit about the Earth. This calls an additional subroutine that graphically displays the intensities and the resulting frequency of those intensities as a range of solar phase angles in a Probability Density Function plot. This document reports the additions and modifications to the subset of the Fragment Rotation Analysis and Lightcurve concerned with the Dynamic Rotation and Probability Density Function plotting subroutines.

  3. Consideration of some fundamental erosion processes encountered in hypervelocity electromagnetic propulsion

    SciTech Connect

    Buckingham, A.C.; Hawke, R.S.

    1982-09-30

    Experimental and theoretical research has been conducted jointly at the Livermore and Los Alamos National laboratories on dc electromagnetic railgun Lorentz accelerators. Pellets weighing a few grams to tens of grams have been launched at velocities up to better than 11 km/s. The research is addressed to attaining repeated launches of samples at hypervelocity in target impact experiments. In these experiments, shock-induced pressures in the tens of megabars range are obtained for high pressure equation-of-state research. Primary energy sources of the order of several hundred kJ to a MJ and induction currents of the order of 1 or more MA are necessary for these launches. Erosion and deformation of the conductor rails and the accelerated sample material are continuing problems. The heating, stress, and erosion resulting from simultaneous imposition of rail induction current, dense plasma (armature) interaction, current distribution, magnetic field stresses and projectile/rail contact friction are examined. It is found that while frictional heating and consequent sliding contact erosion are minor contributors to the overall erosion process, the same cannot be said for plasma impingement, penetration, and almost simultaneous induction current (Joule) heating.

  4. Deformation mechanisms and damage in α-alumina under hypervelocity impact loading

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya; Branicio, Paulo S.

    2008-04-01

    Deformation mechanisms in α-alumina under hypervelocity impact are investigated using molecular dynamics simulations containing 540×106 atoms. A cylindrical projectile impacting normal to the (0001) surface at 18km/s generates large temperature and pressure gradients around the impact face, and consequently local amorphization of the substrate in a surrounding hemispherical region is produced. Away from the impact face, a wide range of deformations emerge and disappear as a function of time under the influence of local stress fields, e.g., basal and pyramidal slips and basal and rhombohedral twins, all of which show good agreement with the experimental and theoretical results. New deformation modes are observed, such as twins along {01¯11}, which propagate at a roughly constant speed of 8km/s and nucleate a large amount of defects where subsequent fractures initiate. The relation between deformation patterns and local stress levels is investigated. During unloading, we observe that microcracks nucleate extensively at the intersections of previous deformations within an hourglass-shaped volume that connects top and bottom free surfaces. From the simulation, the fracture toughness of alumina is estimated to be 2.0±0.5MPa√m. The substrate eventually fails along the surface of the hourglass region during spallation when clusters of substrate material are ejected from both free surfaces.

  5. Survivability to Hypervelocity Impacts of Electrodynamic Tape Tethers for Deorbiting Spacecraft in LEO

    NASA Astrophysics Data System (ADS)

    Francesconi, A.; Giacomuzzo, C.; Lorenzini, E. C.

    2013-08-01

    This paper reports the results of 16 hypervelocity impact experiments on a composite flat electrodynamic tether for LEO spacecraft end-of-life deorbiting. The system is being developed within the EU FP7 BETs program. Impact tests were carried out at CISAS impact facility, with the aim of deriving failure equations that include the impact angle dependence up to grazing incidence. Experiments were realised with 1.5 and 2.3 mm aluminium spheres, at velocities between 3 and 5 km/s and impact angle from 0° to 90° from the tape normal. After a preliminary post-impact inspection of the target, the damage extension on the tape was evaluated using an automatic image processing technique. Ballistic limit equations were developed in the experimental range using a procedure that allows to estimate the uncertainty in the failure predictions starting from the measurement of the damage area. Experiments showed that the impact damage is very close to the projectile size in case of normal impact, while it increases significantly at highly oblique impact angles.

  6. The 3MV Hypervelocity Dust Accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Shu, A.; Collette, A.; Drake, K.; Horanyi, M.; Kempf, S.; Munsat, T.; Northway, P.; Robertson, S.; Sternovsky, Z.; Thomas, E.; Gruen, E.; Srama, R.

    2011-11-01

    Micrometeorite impacts and dusty plasma phenomena can be found in a wide variety of subjects. In many extraplanetary systems, such as in deep space and on airless bodies such as asteroids or the moon, dusty plasmas play a large role in the basic scientific evolution of the environment. Dust can also be captured and studied in dust astronomy in order to better understand the evolution of our universe, similarly to how photons are used in traditional astronomy. At the Colorado Center for Lunar Dust and Atmospheric Studies, we have developed a 3MV hypervelocity dust accelerator in order to study these and other applications of dust and dusty plasmas. This facility is capable of accelerating micron sized dust particles up to 10's of km/s. In addition to this we have several vacuum chambers used for dusty plasma experiments. The large Lunar Environment Impact Laboratory (LEIL) test chamber will be used to study dust levitation, space weathering, and lunar exosphere evolution. A smaller ultrahigh vacuum chamber will be used to detect neutral species in micrometeorite impact ejecta and detect and analyze impact flashes. In addition to this work, graphite tokamak wall tile material will be placed into the beam path to determine damage characteristics from dust in fusion systems.

  7. Subsurface deformation in hypervelocity cratering experiments into high-porosity tuffs

    NASA Astrophysics Data System (ADS)

    Winkler, Rebecca; Poelchau, Michael H.; Moser, Stefan; Kenkmann, Thomas

    2016-08-01

    Hypervelocity impact experiments on porous tuff targets were carried out to determine the effect of porosity on deformation mechanisms in the crater's subsurface. Blocks of Weibern Tuff with about 43% porosity were impacted by 2.5 mm and 12.0 mm diameter steel spheres with velocities between 4.8 km s-1 and 5.6 km s-1. The postimpact subsurface damage was quantified with computer tomography as well as with meso- and microscale analyses of the bisected crater subsurface. The intensity and style of deformation in mineral clasts and the tuff matrix were mapped and their decay with subsurface depth was determined. Subsurface deformation styles include pore space compaction, clast rotation, as well as microfracture formation. Evaluation of the deformation indicates near-surface energy coupling at a calculated depth of burial of ~2 projectile diameters (dp), which is in conflict with the crater shape, which displays a deep, central penetration tube. Subsurface damage extends to ~2 dp beneath the crater floor in the experiments with 2.5 mm projectiles and increases to ~3 dp for 12 mm projectiles. Based on overprinting relationships and the geometrical orientation of deformation features, a sequence of subsurface deformation events was derived (1) matrix compaction, (2) intragranular crack formation in clasts, (3) deformation band formation in the compacted matrix, (4) tensile fracturing.

  8. Characterization of Orbital Debris Via Hyper-Velocity Ground-Based Tests

    NASA Technical Reports Server (NTRS)

    Cowardin, Heather

    2015-01-01

    To replicate a hyper-velocity fragmentation event using modern-day spacecraft materials and construction techniques to better improve the existing DoD and NASA breakup models. DebriSat is intended to be representative of modern LEO satellites.Major design decisions were reviewed and approved by Aerospace subject matter experts from different disciplines. DebriSat includes 7 major subsystems. Attitude determination and control system (ADCS), command and data handling (C&DH), electrical power system (EPS), payload, propulsion, telemetry tracking and command (TT&C), and thermal management. To reduce cost, most components are emulated based on existing design of flight hardware and fabricated with the same materials. A key laboratory-based test, Satellite Orbital debris Characterization Impact Test (SOCIT), supporting the development of the DoD and NASA satellite breakup models was conducted at AEDC in 1992 .Breakup models based on SOCIT have supported many applications and matched on-orbit events reasonably well over the years.

  9. DebriSat: The New Hypervelocity Impact Test for Satellite Breakup Fragment Characterization

    NASA Technical Reports Server (NTRS)

    Cowardin, Heather

    2015-01-01

    To replicate a hyper-velocity fragmentation event using modern-day spacecraft materials and construction techniques to better improve the existing DoD and NASA breakup models: DebriSat is intended to be representative of modern LEO satellites. Major design decisions were reviewed and approved by Aerospace subject matter experts from different disciplines. DebriSat includes 7 major subsystems. Attitude determination and control system (ADCS), command and data handling (C&DH), electrical power system (EPS), payload, propulsion, telemetry tracking and command (TT&C), and thermal management. To reduce cost, most components are emulated based on existing design of flight hardware and fabricated with the same materials. center dotA key laboratory-based test, Satellite Orbital debris Characterization Impact Test (SOCIT), supporting the development of the DoD and NASA satellite breakup models was conducted at AEDC in 1992. Breakup models based on SOCIT have supported many applications and matched on-orbit events reasonably well over the years.

  10. Hypervelocity impact testing of the Space Station utility distribution system carrier

    NASA Technical Reports Server (NTRS)

    Lazaroff, Scott

    1993-01-01

    A two-phase, joint JSC and McDonnell Douglas Aerospace-Huntington Beach hypervelocity impact (HVI) test program was initiated to develop an improved understanding of how meteoroid and orbital debris (M/OD) impacts affect the Space Station Freedom (SSF) avionic and fluid lines routed in the Utility Distribution System (UDS) carrier. This report documents the first phase of the test program which covers nonpowered avionic line segment and pressurized fluid line segment HVI testing. From these tests, a better estimation of avionic line failures is approximately 15 failures per year and could very well drop to around 1 or 2 avionic line failures per year (depending upon the results of the second phase testing of the powered avionic line at White Sands). For the fluid lines, the initial McDonnell Douglas analysis calculated 1 to 2 line failures over a 30 year period. The data obtained from these tests indicate the number of predicted fluid line failures increased slightly to as many as 3 in the first 10 years and up to 15 for the entire 30 year life of SSF.

  11. Fabrication issues and technology development for HELEOS (Hypervelocity Electromagnetic Launcher for Equation of State)

    SciTech Connect

    Susoeff, A.R.; Hawke, R.S.; Balk, J.K.; Hall, C.A.; McDonald, M.J.

    1988-02-01

    Starfire is a joint railgun project of Lawrence Livermore National Laboratory and Sandia National Laboratory and Sandia National Laboratory-Albuquerque. The goal of Starfire is to develop a Hypervelocity Electromagnetic Launcher for Equation of State (HELEOS) experiments. A two-stage light-gas gun is used as pre-injector. Each round-bore HELEOS railgun module is 12.7 mm in diameter and 2.4 m long. The muzzle end of the railgun is connected to a vacuum tank. Common materials and fabrication technology are used in the manufacture of all components,a nd modular design allows for extending the length of the railgun as progress dictates. The launcher uses a ''vee block'' geometry, which is designed to: provide compressive preload; operate with a 300-MPa (3-kbar) internal bore pressure; and easily accommodate interchangeable materials in the bore support structure and rail. We have performed full-scale material testing of the railgun and have developed a precision round-bore fabrication process. Air-gage inspection is used to determine bore diameter and straightness. We have also developed a surface mapping system to document the surface topography of the bore before and after an experiment. This paper presents fabrication details, results of tests conducted, and areas for potential improvement. 12 refs., 6 figs., 1 tab.

  12. High pressure hypervelocity electrothermal wind tunnel performance study and subscale tests

    NASA Technical Reports Server (NTRS)

    Rizkalla, Oussama F.; Chinitz, Wallace; Witherspoon, F. D.; Burton, Rodney L.

    1992-01-01

    The feasibility of a Mach 10 to 20, high pressure electrothermal wind tunnel was assessed. A heater based on a continuous high power electric arc discharge capable of heating air to temperatures above 10,000 K and pressures of 15,000 atm is the key element of this wind tunnel. Results of analytical study indicate that the facility is capable of simulation conditions suitable for hypervelocity airbreathing propulsion testing up to Mach 16. In this case simulation was limited by pressure containment, high nozzle throat heat flux rates, and chemical freezing in the nozzle. The high total pressure capability improved the recombination chemistry in the facility nozzle as chemical equilibrium prevailed to the freezing point. Steady arc discharges were observed with liquid nitrogen flowing into the arc chamber during tests based on the two millisecond test facility. The measured steady pressure in the arc chamber was 4559 psi, which is two times greater than maximum total pressure obtainable in conventional arc heaters.

  13. Spray casting of metallic preforms

    DOEpatents

    Flinn, John E.; Burch, Joseph V.; Sears, James W.

    2000-01-01

    A metal alloy is melted in a crucible and ejected from the bottom of the crucible as a descending stream of molten metal. The descending stream is impacted with a plurality of primary inert gas jets surrounding the molten metal stream to produce a plume of atomized molten metal droplets. An inert gas is blown onto a lower portion of the plume with a plurality of auxiliary inert gas jets to deflect the plume into a more restricted pattern of high droplet density, thereby substantially eliminating unwanted overspray and resulting wasted material. The plume is projected onto a moving substrate to form a monolithic metallic product having generally parallel sides.

  14. Jet Lag in Athletes

    PubMed Central

    Lee, Aaron; Galvez, Juan Carlos

    2012-01-01

    Context: Prolonged transmeridian air travel can impart a physical and emotional burden on athletes in jet lag and travel fatigue. Jet lag may negatively affect the performance of athletes. Study Type: Descriptive review. Evidence Acquisition: A Medline search for articles relating to jet lag was performed (1990-present), as was a search relating to jet lag and athletes (1983-January, 2012). The results were reviewed for relevance. Eighty-nine sources were included in this descriptive review. Results: Behavioral strategies are recommended over pharmacological strategies when traveling with athletes; pharmacological aides may be used on an individual basis. Strategic sleeping, timed exposure to bright light, and the use of melatonin are encouraged. Conclusions: There is strong evidence that mood and cognition are adversely affected by jet lag. Some measures of individual and team performance are adversely affected as well. PMID:23016089

  15. Description of Jet Breakup

    NASA Technical Reports Server (NTRS)

    Papageorgiou, Demetrios T.

    1996-01-01

    In this article we review recent results on the breakup of cylindrical jets of a Newtonian fluid. Capillary forces provide the main driving mechanism and our interest is in the description of the flow as the jet pinches to form drops. The approach is to describe such topological singularities by constructing local (in time and space) similarity solutions from the governing equations. This is described for breakup according to the Euler, Stokes or Navier-Stokes equations. It is found that slender jet theories can be applied when viscosity is present, but for inviscid jets the local shape of the jet at breakup is most likely of a non-slender geometry. Systems of one-dimensional models of the governing equations are solved numerically in order to illustrate these differences.

  16. Multiple jet study

    NASA Technical Reports Server (NTRS)

    Walker, R. E.; Kors, D. L.

    1973-01-01

    Test data is presented which allows determination of jet penetration and mixing of multiple cold air jets into a ducted subsonic heated mainstream flow. Jet-to-mainstream momentum flux ratios ranged from 6 to 60. Temperature profile data is presented at various duct locations up to 24 orifice diameters downstream of the plane of jet injection. Except for two configurations, all geometries investigated had a single row of constant diameter orifices located transverse to the main flow direction. Orifice size and spacing between orifices were varied. Both of these were found to have a significant effect on jet penetration and mixing. The best mixing of the hot and cold streams was achieved with duct height.

  17. Jet physics at CDF

    SciTech Connect

    Melese, P.

    1997-05-01

    We present high E{sub T} jet measurements from CDF at the Fermilab Tevatron Collider. The incfilusive jet cross section at {radical}s = 1800 GeV with {approximately} 5 times more data is compared to the published CDF results, preliminary D0 results, and next-to-leading order QCD predictions. The {summation}E{sub T} cross section is also compared to QCD predictions and the dijet angular distribution is used to place a limit on quark compositeness. The inclusive jet cross section at {radical}s = 630 GeV is compared with that at 1800 GeV to test the QCD predictions for the scaling of jet cross sections with {radical}s. Finally, we present momentum distributions of charged particles in jets and compare them to Modified Leading Log Approximation predictions.

  18. First Production of C60 Nanoparticle Plasma Jet for Study of Disruption Mitigation for ITER

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; Brockington, S.; Case, A.; Messer, S. J.; Witherspoon, F. D.

    2012-10-01

    Unique fast response and large mass-velocity delivery of nanoparticle plasma jets (NPPJs) provide a novel application for ITER disruption mitigation, runaway electrons diagnostics and deep fueling. NPPJs carry a much larger mass than usual gases. An electromagnetic plasma gun provides a very high injection velocity (many km/s). NPPJ has much higher ram pressure than any standard gas injection method and penetrates the tokamak confining magnetic field. Assimilation is enhanced due to the NP large surface-to-volume ratio. Radially expanding NPPJs help achieving toroidal uniformity of radiation power. FAR-TECH's NPPJ system was successfully tested: a coaxial plasma gun prototype (˜35 cm length, 96 kJ energy) using a solid state TiH2/C60 pulsed power cartridge injector produced a hyper-velocity (>4 km/s), high-density (>10^23 m-3), C60 plasma jet in ˜0.5 ms, with ˜1-2 ms overall response-delivery time. We present the TiH2/C60 cartridge injector output characterization (˜180 mg of sublimated C60 gas) and first production results of a high momentum C60 plasma jet (˜0.6 g.km/s).

  19. High Resolution Diagnostics of a Linear Shaped Charge Jet

    SciTech Connect

    Chase, J.B.; Kuklo, R.M.; Shaw, L.L.; Carter, D.L.; Baum, D.W.

    1999-08-10

    The linear shaped charge is designed to produce a knife blade-like flat jet, which will perforate and sever one side of a modestly hard target from the other. This charge is approximately plane wave initiated and used a water pipe quality circular copper liner. To establish the quality of this jet we report about an experiment using several of the Lawrence Livermore National Laboratory high-resolution diagnostics previously published in this meeting [1]. Image converter tube camera stereo image pairs were obtained early in the jet formation process. Individual IC images were taken just after the perforation of a thin steel plate. These pictures are augmented with 70 mm format rotating mirror framing images, orthogonal 450 KeV flash radiograph pairs, and arrival time switches (velocity traps) positioned along the length of the jet edge. We have confirmed that linear shaped charges are subject to the same need for high quality copper as any other metal jetting device.

  20. Liquid gallium jet-plasma interaction studies in ISTTOK tokamak

    NASA Astrophysics Data System (ADS)

    Gomes, R. B.; Fernandes, H.; Silva, C.; Sarakovskis, A.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I.; Alekseyv, A.

    2009-06-01

    Liquid metals have been pointed out as a suitable solution to solve problems related to the use of solid walls submitted to high power loads allowing, simultaneously, an efficient heat exhaustion process from fusion devices. The most promising candidate materials are lithium and gallium. However, lithium has a short liquid state temperature range when compared with gallium. To explore further this property, ISTTOK tokamak is being used to test the interaction of a free flying liquid gallium jet with the plasma. ISTTOK has been successfully operated with this jet without noticeable discharge degradation and no severe effect on the main plasma parameters or a significant plasma contamination by liquid metal. Additionally the response of an infrared sensor, intended to measure the jet surface temperature increase during its interaction with the plasma, has been studied. The jet power extraction capability is extrapolated from the heat flux profiles measured in ISTTOK plasmas.

  1. Study of Damage of Gas-filled Spherical Pressure Vassel Subjected to Hypervelocity Impact by Space Debris with Different Velocity

    NASA Astrophysics Data System (ADS)

    Cai, Yuan; Pang, Baojun; Jia, Bin

    2013-08-01

    As an important component of spacecraft, if a gas-filled pressure vessel is impacted by space debris, it might occur even overall bursting. Spherical aluminum projectiles are used to simulate space debris impacting gas-filled spherical pressure vessel with hypervelocity. Projectiles impact places with the same thickness in different tests. By analyzing the maximum gas pressure of the spherical vessel, the inflation pressure is determined: 1.075MPa. By numerical simulation, the critical impact velocity to perforate the front wall is determined: 2.02mm ~ 2.31mm. As the projectile velocity increases, the damage patterns of the back wall are of different bulged outwards patterns.

  2. A Hypervelocity Experimental Research Database (HERD): Support for the Wright Laboratory Armament Directorate Code Validation Program (COVAL)

    SciTech Connect

    Mullin, S.A.; Anderson, C.E. Jr.; Hertel, E.S. Jr.; Hunt, R.D.

    1994-10-01

    The Hypervelocity Experimental Research Database (HERD) described in this paper was developed to aid researchers with code validation for impacts that occur at velocities faster than the testable regime. Codes of concern include both hydrocodes and fast-running analytical or semi-empirical models used to predict the impact phenomenology and damage that results to projectiles and targets. There are several well documented experimental programs that can serve as benchmarks for code validation; these are identified and described. Recommendations for further experimentation (a canonical problem) to provide validation data are also discussed.

  3. Jet Noise Suppression

    NASA Technical Reports Server (NTRS)

    Gliebe, P. R.; Brausch, J. F.; Majjigi, R. K.; Lee, R.

    1991-01-01

    The objectives of this chapter are to review and summarize the jet noise suppression technology, to provide a physical and theoretical model to explain the measured jet noise suppression characteristics of different concepts, and to provide a set of guidelines for evolving jet noise suppression designs. The underlying principle for all jet noise suppression devices is to enhance rapid mixing (i.e., diffusion) of the jet plume by geometric and aerothermodynamic means. In the case of supersonic jets, the shock-cell broadband noise reduction is effectively accomplished by the elimination or mitigation of the shock-cell structure. So far, the diffusion concepts have predominantly concentrated on jet momentum and energy (kinetic and thermal) diffusion, in that order, and have yielded better noise reduction than the simple conical nozzles. A critical technology issue that needs resolution is the effect of flight on the noise suppression potential of mechanical suppressor nozzles. A more thorough investigation of this mechanism is necessary for the successful development and design of an acceptable noise suppression device for future high-speed civil transports.

  4. Experimental investigation of charged liquid jet efflux from a capillary

    NASA Astrophysics Data System (ADS)

    Zhakin, A. I.; Belov, P. A.; Kuz'ko, A. E.

    2013-03-01

    The shapes and electrical characteristics of charged liquid (water, ethanol, glycerol, castor oil) jets emitted from a metal capillary have been experimentally studied depending on the applied high voltage. A map of efflux regimes in the flow velocity-applied voltage coordinates is constructed for water. The effects of medium viscosity, surface tension, and charge relaxation time on the laws of jet efflux are analyzed.

  5. Interaction of a Liquid Gallium Jet with ISTTOK Edge Plasmas

    NASA Astrophysics Data System (ADS)

    Gomes, R. B.; Fernandes, H.; Silva, C.; Sarakovskis, A.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I.

    2008-04-01

    The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages in the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaust from fusion devices. Presently the most promising candidate materials are lithium and gallium. However, lithium has a short liquid state range when compared, for example, with gallium that has essentially better thermal properties and lower vapor pressure. To explore further these properties, ISTTOK tokamak is being used to test the interaction of a free flying, fully formed liquid gallium jet with the plasma. The interacting, 2.3 mm diameter, jet is generated by hydrostatic pressure and has a 2.5 m/s flow velocity. The liquid metal injector has been build to allow the positioning of the jet inside the tokamak chamber, within a 13 mm range. This paper presents the first obtained experimental results concerning the liquid gallium jet-plasma interaction. A stable jet has been obtained, which was not noticeably affected by the magnetic field transients. ISTTOK has been successfully operated with the gallium jet without degradation of the discharge or a significant plasma contamination by liquid metal. This observation is supported by spectroscopic measurements showing that gallium radiation is limited to the region around the jet. Furthermore, the power deposited on the jet has been evaluated at different radial locations and the surface temperature increase estimated.

  6. Angular Scaling In Jets

    SciTech Connect

    Jankowiak, Martin; Larkoski, Andrew J.; /SLAC

    2012-02-17

    We introduce a jet shape observable defined for an ensemble of jets in terms of two-particle angular correlations and a resolution parameter R. This quantity is infrared and collinear safe and can be interpreted as a scaling exponent for the angular distribution of mass inside the jet. For small R it is close to the value 2 as a consequence of the approximately scale invariant QCD dynamics. For large R it is sensitive to non-perturbative effects. We describe the use of this correlation function for tests of QCD, for studying underlying event and pile-up effects, and for tuning Monte Carlo event generators.

  7. Tektite origin by hypervelocity asteroidal or cometary impact: The quest for the source craters

    NASA Astrophysics Data System (ADS)

    Koeberl, Christian

    Tektites are natural glasses that are chemically homogeneous, often spherically symmetrical objects several centimeters in size, and occur in four known strewn fields on the surface of the Earth: the North American, moldavite (or Central European), Ivory Coast, and Australasian strewn fields. Tektites found within such strewn fields are related to each other with respect to their petrological, physical, and chemical properties as well as their age. A theory of tektite origin needs to explain the similarity of tektites in respect to age and certain aspects of isotopic and chemical composition within one strewn field, as well as the variety of tektite materials present in each strewn field. In addition to tektites on land, microtektites (which are generally less than 1 mm in diameter) have been found in deep-sea cores. Tektites are classified into three groups: (1) normal or splash-form tektites, (2) aerodynamically shaped tektites, and (3) Muong Nong-type tektites (sometimes also called layered tektites). The aerodynamic ablation results from partial remelting of glass during atmospheric passage after it was ejected outside the terrestrial atmosphere and quenched from a hot liquid. Aerodynamically shaped tektites are known mainly from the Australasian strewn field where they occur as flanged-button australites. The shapes of splash-form tektites (spheres, droplets, teardrops, dumbbells, etc., or fragments thereof) are the result of the solidification of rotating liquids in the air or vacuum. Mainly due to chemical studies, it is now commonly accepted that tektites are the product of melting and quenching of terrestrial rocks during hypervelocity impact on the Earth. The chemistry of tektites is in many respects identical to the composition of upper crustal material.

  8. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies.

    PubMed

    Shu, Anthony; Collette, Andrew; Drake, Keith; Grün, Eberhard; Horányi, Mihály; Kempf, Sascha; Mocker, Anna; Munsat, Tobin; Northway, Paige; Srama, Ralf; Sternovsky, Zoltán; Thomas, Evan

    2012-07-01

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Institüt für Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10(-7) torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10(-10) torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments. PMID:22852725

  9. Bacterial Spores in Granite Survive Hypervelocity Launch by Spallation: Implications for Lithopanspermia

    NASA Astrophysics Data System (ADS)

    Fajardo-Cavazos, Patricia; Langenhorst, Falko; Melosh, H. Jay; Nicholson, Wayne L.

    2009-09-01

    Bacterial spores are considered good candidates for endolithic life-forms that could survive interplanetary transport by natural impact processes, i. e., lithopanspermia. Organisms within rock can only embark on an interplanetary journey if they survive ejection from the surface of the donor planet and the associated extremes of compressional shock, heating, and acceleration. Previous simulation experiments have measured each of these three stresses more or less in isolation of one another, and results to date indicate that spores of the model organism Bacillus subtilis can survive each stress applied singly. Few simulations, however, have combined all three stresses simultaneously. Because considerable experimental and theoretical evidence supports a spallation mechanism for launch, we devised an experimental simulation of launch by spallation using the Ames Vertical Gun Range (AVGR). B. subtilis spores were applied to the surface of a granite target that was impacted from above by an aluminum projectile fired at 5.4 km/s. Granite spall fragments were captured in a foam recovery fixture and then recovered and assayed for shock damage by transmission electron microscopy and for spore survival by viability assays. Peak shock pressure at the impact site was calculated to be 57.1 Pa, though recovered spall fragments were only very lightly shocked at pressures of 5-7 GPa. Spore survival was calculated to be on the order of 10-5, which is in agreement with results of previous static compressional shock experiments. These results demonstrate that endolithic spores can survive launch by spallation from a hypervelocity impact, which lends further evidence in favor of lithopanspermia theory.

  10. Characterization of Oribtal Debris via Hyper-Velocity Ground-Based Tests

    NASA Technical Reports Server (NTRS)

    Cowardin, H.

    2015-01-01

    Existing DoD and NASA satellite breakup models are based on a key laboratory-based test, Satellite Orbital debris Characterization Impact Test (SOCIT), which has supported many applications and matched on-orbit events involving older satellite designs reasonably well over the years. In order to update and improve the break-up models and the NASA Size Estimation Model (SEM) for events involving more modern satellite designs, the NASA Orbital Debris Program Office has worked in collaboration with the University of Florida to replicate a hypervelocity impact using a satellite built with modern-day spacecraft materials and construction techniques. The spacecraft, called DebriSat, was intended to be a representative of modern LEO satellites and all major designs decisions were reviewed and approved by subject matter experts at Aerospace Corporation. DebriSat is composed of 7 major subsystems including attitude determination and control system (ADCS), command and data handling (C&DH), electrical power system (EPS), payload, propulsion, telemetry tracking and command (TT&C), and thermal management. To reduce cost, most components are emulated based on existing design of flight hardware and fabricated with the same materials. All fragments down to 2 mm is size will be characterized via material, size, shape, bulk density, and the associated data will be stored in a database for multiple users to access. Laboratory radar and optical measurements will be performed on a subset of fragments to provide a better understanding of the data products from orbital debris acquired from ground-based radars and telescopes. The resulting data analysis from DebriSat will be used to update break-up models and develop the first optical SEM in conjunction with updates into the current NASA SEM. The characterization of the fragmentation will be discussed in the subsequent presentation.

  11. CFD Analysis of Mixing Characteristics of Several Fuel Injectors at Hypervelocity Flow Conditions

    NASA Technical Reports Server (NTRS)

    Drozda, Tomasz G.; Drummond, J. Philip; Baurle, Robert A.

    2016-01-01

    CFD analysis is presented of the mixing characteristics and performance of three fuel injectors at hypervelocity flow conditions. The calculations were carried out using the VULCAN-CFD solver and Reynolds-Averaged Simulations (RAS). The high Mach number flow conditions match those proposed for the planned experiments conducted as a part of the Enhanced Injection and Mixing Project (EIMP) at the NASA Langley Research Center. The EIMP aims to investigate scramjet fuel injection and mixing physics, improve the understanding of underlying physical processes, and develop enhancement strategies and functional relationships relevant to flight Mach numbers greater than eight. Because of the high Mach number flow considered, the injectors consist of a fuel placement device, a strut; and a fluidic vortical mixer, a ramp. These devices accomplish the necessary task of distributing and mixing fuel into the supersonic cross-flow albeit via different strategies. Both of these devices were previously studied at lower flight Mach numbers where they exhibited promising performance in terms of mixing efficiency and total pressure recovery. For comparison, a flush-wall injector is also included. This type of injector generally represents the simplest method of introducing fuel into a scramjet combustor, however, at high flight Mach number conditions, the dynamic pressure needed to induce sufficient fuel penetration may be difficult to achieve along with other requirements such as achieving desired levels of fuel-to-air mixing at the required equivalence ratio. The three injectors represent the baseline configurations planned for the experiments. The current work discusses the mixing flow field behavior and differences among the three fuel injectors, mixing performance as described by the mixing efficiency and the total pressure recovery, and performance considerations based on the thrust potential.

  12. Theoretical hypervelocity ballistic limit for single or double plates using nonlinear modal analysis

    NASA Technical Reports Server (NTRS)

    Hui, David

    1990-01-01

    The original research on the use on nonlinear vibration technique to solve for the hypervelocity ballistic limit for double plates is examined. Such structure is commonly found in typical Space Station design where the incoming space or man-made debris would be fragmented upon hitting the outer plate (shield) and the subsequent impact on the main wall would result in a much reduced damge of the space station or spacecraft. The existing few theoretical impact equations do not agree well with each other. The existing computer code bumper used at NASA-Johnson Space Center appears to predict an unconservative ballistic limit when compared with experimental data where the velocity ranges from 3 km/s to 8 km/s. Such unconservative prediction is unacceptable from a practical safe design point of view. The bumper code is based on Wilkinson's (1968) paper and his equations have not been improved nor modified even though they are viewed with suspicion due to lack of agreement with experiments. To make matters worse, there is not another theory which is better than Wilkinson's equation and the designers are forced to use purely empirical Nysmith (1969) or semiempirical equations developed by Cour-Palais in 1969. The Cour-Palais equations were later modified empirically in 1989. The purpose of the present investigation is to examine the many assumptions of the Wilkinson equation. An attempt is made to present design charts based on the modified-Wilkinson equation so that the designer can get a feel of the ranges of the parameters which are of interest and discard a huge range of parameters, thus, significantly reducing the number of test shots required. The analysis is based on a solution of the governing nonlinear differential equations for a plate, assuming axisymmetric behavior using polar coordinates.

  13. Tektite origin by hypervelocity asteroidal or cometary impact: The quest for the source craters

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian

    1992-01-01

    Tektites are natural glasses that are chemically homogeneous, often spherically symmetrical objects several centimeters in size, and occur in four known strewn fields on the surface of the Earth: the North American, moldavite (or Central European), Ivory Coast, and Australasian strewn fields. Tektites found within such strewn fields are related to each other with respect to their petrological, physical, and chemical properties as well as their age. A theory of tektite origin needs to explain the similarity of tektites in respect to age and certain aspects of isotopic and chemical composition within one strewn field, as well as the variety of tektite materials present in each strewn field. In addition to tektites on land, microtektites (which are generally less than 1 mm in diameter) have been found in deep-sea cores. Tektites are classified into three groups: (1) normal or splash-form tektites, (2) aerodynamically shaped tektites, and (3) Muong Nong-type tektites (sometimes also called layered tektites). The aerodynamic ablation results from partial remelting of glass during atmospheric passage after it was ejected outside the terrestrial atmosphere and quenched from a hot liquid. Aerodynamically shaped tektites are known mainly from the Australasian strewn field where they occur as flanged-button australites. The shapes of splash-form tektites (spheres, droplets, teardrops, dumbbells, etc., or fragments thereof) are the result of the solidification of rotating liquids in the air or vacuum. Mainly due to chemical studies, it is now commonly accepted that tektites are the product of melting and quenching of terrestrial rocks during hypervelocity impact on the Earth. The chemistry of tektites is in many respects identical to the composition of upper crustal material.

  14. Scaling of sub-surface deformation in hypervelocity impact experiments on porous sandstone

    NASA Astrophysics Data System (ADS)

    Buhl, Elmar; Poelchau, Michael; Dresen, Georg; Kenkmann, Thomas

    2014-11-01

    Two hypervelocity impact experiments into dry sandstone (Seeberger Sandstein, ~ 23% porosity), performed under similar impact conditions but with different projectile sizes, have been analyzed to investigate the size scaling of impact damage. For one experiment a 2.5 mm steel projectile was impacted at 4.8 km s- 1 onto a sandstone cube of 20 cm side length. For the other experiment a 10 mm iron meteorite projectile was impacted at 4.6 km s- 1 onto a sandstone cube of 50 cm side length. The resulting kinetic impact energies of 773 and 42,627 J led to crater cavities of 7600 and 612,000 mm3. Investigation of thin sections along cross-sections through both craters revealed that the same deformation microstructures are present in both experiments. The occurrence of different microstructural patterns was mapped and zones of characteristic deformation were defined. This mapping was used to calculate the volumes of material deformed by specific mechanisms. Comparing the results, normalized to the size of the projectile, showed that the sub-surface damage is very similar in size, volume and geometry for both experiments. Analysis of deformation bands found in both experiments regarding their long axes orientation showed that these features are developed under shear deformation. Particle size distributions (PSD), expressed as power-law fits, were measured to quantify the impact damage. Comparison showed that the decay of the power-law exponents with increasing distance from the impact point source is similar for both experiments. Reconstruction of the loading path allowed to infer the stresses under which distinct deformation microstructures are developed.

  15. Bacterial spores in granite survive hypervelocity launch by spallation: implications for lithopanspermia.

    PubMed

    Fajardo-Cavazos, Patricia; Langenhorst, Falko; Melosh, H Jay; Nicholson, Wayne L

    2009-09-01

    Bacterial spores are considered good candidates for endolithic life-forms that could survive interplanetary transport by natural impact processes, i.e., lithopanspermia. Organisms within rock can only embark on an interplanetary journey if they survive ejection from the surface of the donor planet and the associated extremes of compressional shock, heating, and acceleration. Previous simulation experiments have measured each of these three stresses more or less in isolation of one another, and results to date indicate that spores of the model organism Bacillus subtilis can survive each stress applied singly. Few simulations, however, have combined all three stresses simultaneously. Because considerable experimental and theoretical evidence supports a spallation mechanism for launch, we devised an experimental simulation of launch by spallation using the Ames Vertical Gun Range (AVGR). B. subtilis spores were applied to the surface of a granite target that was impacted from above by an aluminum projectile fired at 5.4 km/s. Granite spall fragments were captured in a foam recovery fixture and then recovered and assayed for shock damage by transmission electron microscopy and for spore survival by viability assays. Peak shock pressure at the impact site was calculated to be 57.1 GPa, though recovered spall fragments were only very lightly shocked at pressures of 5-7 GPa. Spore survival was calculated to be on the order of 10(-5), which is in agreement with results of previous static compressional shock experiments. These results demonstrate that endolithic spores can survive launch by spallation from a hypervelocity impact, which lends further evidence in favor of lithopanspermia theory. PMID:19778276

  16. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

    SciTech Connect

    Shu, Anthony; Horanyi, Mihaly; Kempf, Sascha; Thomas, Evan; Collette, Andrew; Drake, Keith; Northway, Paige; Gruen, Eberhard; Mocker, Anna; Munsat, Tobin; Srama, Ralf; and others

    2012-07-15

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Instituet fuer Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10{sup -7} torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10{sup -10} torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

  17. The Stability of Radiatively Cooling Jets I. Linear Analysis

    NASA Technical Reports Server (NTRS)

    Hardee, Philip E.; Stone, James M.

    1997-01-01

    The results of a spatial stability analysis of a two-dimensional slab jet, in which optically thin radiative cooling is dynamically important, are presented. We study both magnetized and unmagnetized jets at external Mach numbers of 5 and 20. We model the cooling rate by using two different cooling curves: one appropriate to interstellar gas, and the other to photoionized gas of reduced metallicity. Thus, our results will be applicable to both protostellar (Herbig-Haro) jets and optical jets from active galactic nuclei. We present analytical solutions to the dispersion relations in useful limits and solve the dispersion relations numerically over a broad range of perturbation frequencies. We find that the growth rates and wavelengths of the unstable Kelvin-Helmholtz (K-H) modes are significantly different from the adiabatic limit, and that the form of the cooling function strongly affects the results. In particular, if the cooling curve is a steep function of temperature in the neighborhood of the equilibrium state, then the growth of K-H modes is reduced relative to the adiabatic jet. On the other hand, if the cooling curve is a shallow function of temperature, then the growth of K-H modes can be enhanced relative to the adiabatic jet by the increase in cooling relative to heating in overdense regions. Inclusion of a dynamically important magnetic field does not strongly modify the important differences between an adiabatic jet and a cooling jet, provided the jet is highly supermagnetosonic and not magnetic pressure-dominated. In the latter case, the unstable modes behave more like the transmagnetosonic magnetic pressure-dominated adiabatic limit. We also plot fluid displacement surfaces associated with the various waves in a cooling jet in order to predict the structures that might arise in the nonlinear regime. This analysis predicts that low-frequency surface waves and the lowest order body modes will be the most effective at producing observable features in

  18. Atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.

    1999-01-01

    Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

  19. Dilution jet mixing program

    NASA Technical Reports Server (NTRS)

    Srinivasan, R.; Coleman, E.; Johnson, K.

    1984-01-01

    Parametric tests were conducted to quantify the mixing of opposed rows of jets (two-sided injection) in a confined cross flow. Results show that jet penetrations for two sided injections are less than that for single-sided injections, but the jet spreading rates are faster for a given momentum ratio and orifice plate. Flow area convergence generally enhances mixing. Mixing characteristics with asymmetric and symmetric convergence are similar. For constant momentum ratio, the optimum S/H(0) with in-line injections is one half the optimum value for single sided injections. For staggered injections, the optimum S/H(0) is twice the optimum value for single-sided injection. The correlations developed predicted the temperature distributions within first order accuracy and provide a useful tool for predicting jet trajectory and temperature profiles in the dilution zone with two-sided injections.

  20. Jet lag prevention

    MedlinePlus

    ... your internal clock before you travel. While in flight: DO NOT sleep unless it matches the bedtime ... decrease jet lag. If you will be in flight during the bedtime of your destination, take some ...

  1. Counterflowing Jet Subsystem Design

    NASA Technical Reports Server (NTRS)

    Farr, Rebecca; Daso, Endwell; Pritchett, Victor; Wang, Ten-See

    2010-01-01

    A counterflowing jet design (a spacecraft and trans-atmospheric subsystem) employs centrally located, supersonic cold gas jets on the face of the vehicle, ejecting into the oncoming free stream. Depending on the supersonic free-stream conditions and the ejected mass flow rate of the counterflowing jets, the bow shock of the vehicle is moved upstream, further away from the vehicle. This results in an increasing shock standoff distance of the bow shock with a progressively weaker shock. At a critical jet mass flow rate, the bow shock becomes so weak that it is transformed into a series of compression waves spread out in a much wider region, thus significantly modifying the flow that wets the outer surfaces, with an attendant reduction in wave and skin friction drag and aerothermal loads.

  2. Jets in hadronic reactions

    SciTech Connect

    Paige, F.E.

    1983-01-01

    Recent experimental data on the properties of jets in hadronic reactions are reviewed and compared with theoretical expectations. Jets are clearly established as the dominant process for high E/sub T/ events in hadronic reactions. The cross section and the other properties of these events are in qualitative and even semiquantitative agreement with expectations based on perturbative QCD. However, we can not yet make precise tests of QCD, primarily because there are substantial uncertainties in the theoretical calculations. 45 references. (WHK)

  3. Hypervelocity Impact Effect of Molecules from Enceladus' Plume and Titan's Upper Atmosphere on NASA's Cassini Spectrometer from Reactive Dynamics Simulation

    NASA Astrophysics Data System (ADS)

    Jaramillo-Botero, Andres; An, Qi; Cheng, Mu-Jeng; Goddard, William A., III; Beegle, Luther W.; Hodyss, Robert

    2012-11-01

    The NASA/ESA Cassini probe of Saturn analyzed the molecular composition of plumes emanating from one of its moons, Enceladus, and the upper atmosphere of another, Titan. However, interpretation of this data is complicated by the hypervelocity (HV) flybys of up to ˜18km/sec that cause substantial molecular fragmentation. To interpret this data we use quantum mechanical based reactive force fields to simulate the HV impact of various molecular species and ice clathrates on oxidized titanium surfaces mimicking those in Cassini’s neutral and ion mass spectrometer (INMS). The predicted velocity dependent fragmentation patterns and composition mixing ratios agree with INMS data providing the means for identifying the molecules in the plume. We used our simulations to predict the surface damage from the HV impacts on the INMS interior walls, which we suggest acts as a titanium sublimation pump that could alter the instrument’s readings. These results show how the theory can identify chemical events from hypervelocity impacts in space plumes and atmospheres, providing in turn clues to the internal structure of the corresponding sources (e.g., Enceladus). This may be valuable in steering modifications in future missions.

  4. Hypervelocity impact effect of molecules from Enceladus' plume and Titan's upper atmosphere on NASA's Cassini spectrometer from reactive dynamics simulation.

    PubMed

    Jaramillo-Botero, Andres; An, Qi; Cheng, Mu-Jeng; Goddard, William A; Beegle, Luther W; Hodyss, Robert

    2012-11-21

    The NASA/ESA Cassini probe of Saturn analyzed the molecular composition of plumes emanating from one of its moons, Enceladus, and the upper atmosphere of another, Titan. However, interpretation of this data is complicated by the hypervelocity (HV) flybys of up to ~18 km/sec that cause substantial molecular fragmentation. To interpret this data we use quantum mechanical based reactive force fields to simulate the HV impact of various molecular species and ice clathrates on oxidized titanium surfaces mimicking those in Cassini's neutral and ion mass spectrometer (INMS). The predicted velocity dependent fragmentation patterns and composition mixing ratios agree with INMS data providing the means for identifying the molecules in the plume. We used our simulations to predict the surface damage from the HV impacts on the INMS interior walls, which we suggest acts as a titanium sublimation pump that could alter the instrument's readings. These results show how the theory can identify chemical events from hypervelocity impacts in space plumes and atmospheres, providing in turn clues to the internal structure of the corresponding sources (e.g., Enceladus). This may be valuable in steering modifications in future missions. PMID:23215593

  5. A comparative study between experimental results and numerical predictions of multi-wall structural response to hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Peck, Jeffrey A.

    1992-01-01

    Over the last three decades, multiwall structures have been analyzed extensively, primarily through experiment, as a means of increasing the protection afforded to spacecraft structure. However, as structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under impact loading conditions. This paper presents the results of a preliminary numerical/experimental investigation of the hypervelocity impact response of multiwall structures. The results of experimental high-speed impact tests are compared against the predictions of the HULL hydrodynamic computer code. It is shown that the hypervelocity impact response characteristics of a specific system cannot be accurately predicted from a limited number of HULL code impact simulations. However, if a wide range of impact loadings conditions are considered, then the ballistic limit curve of the system based on the entire series of numerical simulations can be used as a relatively accurate indication of actual system response.

  6. Radiation from Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Sol, H.; Medvedev, M.; Zhang, B.; Nordlund, A.; Frederiksen, J. T.; Fishman, G. J.; Preece, R.

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  7. Gas Flow and Electric Field Characterization in Plasma Jets for Biomedical Applications: From Single Jet to Multi Jet Arrays

    NASA Astrophysics Data System (ADS)

    Robert, Eric

    2015-09-01

    This work reports first on time-resolved measurement of longitudinal and radial electric fields (EF) associated with plasma propagation in dielectric capillaries. Plasma propagation occurs in a region where longitudinal EF exists ahead the ionization front position revealed from plasma emission with ICCD measurement. The ionization front propagation induces the sudden rise of a radial EF component. Both of these EF components have a few kV/cm in amplitude for helium or neon plasmas. Their amplitude is kept almost constant along a few tens of cm long capillary. The key role of the voltage pulse polarity and the drastic impact of the presence of a target in front of the plasma jet are discussed from Schlieren images. All these experimental measurements are in excellent agreement with model calculations which are used to infer EF data on capillary axis. EF diagnostics in the plasma plume in the free jet mode but also in contact with various targets is proposed. The combination of intense transient EF, both of ns and µs duration, together with significant transient reactive species generation during plasma jet treatments may be reconsidered. Typical EF amplitudes likely to induce electrostimulation, electroporation are indeed probably achieved in many in vivo protocols. Stimulation of tissue oxygenation, blood flow rate modulation and more recently immune system triggering may be examples where EF could play a significant role. The second part of this work is dedicated to the development of multi jets, using two different setups, based on a single plasma source. Plasma splitting in dielectric tubes drilled with sub millimetric orifices, but also plasma transfer across metallic tubes equipped with such orifices are analyzed from ICCD imaging and time resolved EF measurements. This allows for the design of plasma jet arrays but also emphasizes the necessity to account for voltage pulse polarity, target potential status, consecutive helium flow modulation and

  8. Radio-wave emission due to hypervelocity impacts and its correlation with optical observations

    NASA Astrophysics Data System (ADS)

    Takano, T.; Maki, K.; Yamori, A.

    This paper describes the most interesting phenomena of radio-wave emission due to hypervelocity impacts. A projectile of polycarbonate with 1.1 g weight was accelerated by a rail gun to 3.8 km/sec, and hit two targets which are a 2 mm thick aluminum plate upstream and a 45 mm diameter aluminum column downstream, respectively. The projectile first breaks wires to give a triggering signal to a data recorder, then penetrates the aluminum plate, and finally hit the column, The emitted radio-waves propagate through the chamber window, and are received by antennas at each frequency band. The receivers in 22 GHz- and 2 GHz-bands consist of a low noise amplifier, a mixer, a local oscillator and an IF amplifier , respectively. The receiver in 1 MHz-band is a simple RF amplifier. The outputs of all receivers are fed to a data recorder which is actually a high-speed digital oscilloscope with a large amount of memory. The radio-waves were successfully recorded in 22 GHz-band with 500 MHz bandwidth, in 2 GHz-band with 300 MHz bandwidth, and in 1MHz-band. The waveforms in 22 GHz- and 2 GHz-bands coincide well each other, and are composed of two groups of sharp impulses with a separation of about 20 micro seconds. The width of an impulse is less than 2 n sec. which is the resolution limit of the data recorder. We carried out optical observations using an ultra-high speed camera simultaneously through another window of the chamber. The time interval between scenes is 2 micro sec. We can see a faint light of the projectile before the first impact to the plate, and then a brilliant gas exploding backward from the plate and forward to the column. After hitting the column target, the brilliant gas flows to the chamber wall and is reflected back to make a mixture with dark gas in the chamber. Excellent correlation between radio-wave emission and the observed optical phenomena was obtained in the experiment. It is easily conceived that the radio-waves consist of quite a wide frequency

  9. Identification of minerals and meteoritic materials via Raman techniques after capture in hypervelocity impacts on aerogel

    SciTech Connect

    Burchell, M J; Mann, J; Creighton, J A; Kearsley, A; Graham, G A; Esposito, A P; Franchi, I A; Westphal, A J; Snead, C

    2004-10-04

    For this study, an extensive suite of mineral particles analogous to components of cosmic dust were tested to determine if their Raman signatures can be recognized after hypervelocity capture in aerogel. The mineral particles were mainly of greater than 20 micrometers in size and were accelerated onto the silica aerogel by light gas gun shots. It was found that all the individual minerals captured in aerogel could be subsequently identified using Raman (or fluorescent) spectra. The beam spot size used for the laser illumination was of the order of 5 micrometers, and in some cases the captured particles were of a similar small size. In some samples fired into aerogel there was observed a shift in the wavenumbers of some of the Raman bands, a result of the trapped particles being at quite high temperatures due to heating by the laser. Temperatures of samples under laser illumination were estimated from the relative intensities of Stokes and anti-Stokes Raman bands, or, in the case of ruby particles, from the wavenumber of fluorescence bands excited by the laser. It was found that the temperature of particles in aerogel varied greatly, dependent upon laser power and the nature of the particle. In the worst case, some particles were shown to have temperatures in the 500-700 C range at a laser power of about 3 mW at the sample. However most of the mineral particles examined at this laser power had temperatures below 200 C. This is sufficiently low a temperature not to damage most materials expected to be found captured in aerogel in space. In addition, selected meteorite samples were examined to obtain Raman signatures of their constituent minerals and were then shot into aerogel. It was possible to find several Raman signatures after capture in aerogel and obtain a Raman map of a whole grain in situ in the aerogel. Finally, a Raman analysis was carried out of a particle captured in aerogel in space and carbonaceous material identified. In general therefore it is

  10. Effects of Hypervelocity Impacts on Silicone Elastomer Seals and Mating Aluminum Surfaces

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Steinetz, Bruce M.

    2009-01-01

    While in space silicone based elastomer seals planned for use on NASA's Crew Exploration Vehicle (CEV) are exposed to threats from micrometeoroids and orbital debris (MMOD). An understanding of these threats is required to assess risks to the crew, the CEV orbiter, and missions. An Earth based campaign of hypervelocity impacts on small scale seal rings has been done to help estimate MMOD threats to the primary docking seal being developed for the Low Impact Docking System (LIDS). LIDS is being developed to enable the CEV to dock to the ISS (International Space Station) or to Altair (NASA's next lunar lander). The silicone seal on LIDS seals against aluminum alloy flanges on ISS or Altair. Since the integrity of a seal depends on both sealing surfaces, aluminum targets were also impacted. The variables considered in this study included projectile mass, density, speed, incidence angle, seal materials, and target surface treatments and coatings. Most of the impacts used a velocity near 8 km/s and spherical aluminum projectiles (density = 2.7 g/cubic cm), however, a few tests were done near 5.6 km/s. Tests were also performed using projectile densities of 7.7, 2.79, 2.5 or 1.14 g/cubic cm. Projectile incidence angles examined included 0 deg, 45 deg, and 60 deg from normal to the plane of the target. Elastomer compounds impacted include Parker's S0383-70 and Esterline's ELA-SA-401 in the as received condition, or after an atomic oxygen treatment. Bare, anodized and nickel coated aluminum targets were tested simulating the candidate mating seal surface materials. After impact, seals and aluminum plates were leak tested: damaged seals were tested against an undamaged aluminum plate; and undamaged seals were placed at various locations over craters in aluminum plates. It has been shown that silicone elastomer seals can withstand an impressive level of damage before leaking beyond allowable limits. In general on the tests performed to date, the diameter of the crater in

  11. Effects of Hypervelocity Impacts on Silicone Elastomer Seals and Mating Aluminum Surfaces

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Steinetz, Bruce M.

    2009-01-01

    While in space silicone based elastomer seals planned for use on NASA's Crew Exploration Vehicle (CEV) are exposed to threats from micrometeoroids and orbital debris (MMOD). An understanding of these threats is required to assess risks to the crew, the CEV orbiter, and missions. An Earth based campaign of hypervelocity impacts on small scale seal rings has been done to help estimate MMOD threats to the primary docking seal being developed for the Low Impact Docking System (LIDS). LIDS is being developed to enable the CEV to dock to the ISS (International Space Station) or to Altair (NASA's next lunar lander). The silicone seal on LIDS seals against aluminum alloy flanges on ISS or Altair. Since the integrity of a seal depends on both sealing surfaces, aluminum targets were also impacted. The variables considered in this study included projectile mass, density, speed, incidence angle, seal materials, and target surface treatments and coatings. Most of the impacts used a velocity near 8 km/s and spherical aluminum projectiles (density = 2.7 g/cubic centimeter), however, a few tests were done near 5.6 km/s. Tests were also performed using projectile densities of 7.7, 2.79, 2.5 or 1.14 g/cubic centimeter. Projectile incidence angles examined included 0 degrees, 45 degrees , and 60 degrees from normal to the plane of the target. Elastomer compounds impacted include Parker's S0383-70 and Esterline's ELA-SA-401 in the as received condition, or after an atomic oxygen treatment. Bare, anodized and nickel coated aluminum targets were tested simulating the candidate mating seal surface materials. After impact, seals and aluminum plates were leak tested: damaged seals were tested against an undamaged aluminum plate; and undamaged seals were placed at various locations over craters in aluminum plates. It has been shown that silicone elastomer seals can withstand an impressive level of damage before leaking beyond allowable limits. In general on the tests performed to date, the

  12. Impulsively started incompressible turbulent jet

    SciTech Connect

    Witze, P O

    1980-10-01

    Hot-film anemometer measurements are presented for the centerline velocity of a suddenly started jet of air. The tip penetration of the jet is shown to be proportional to the square-root of time. A theoretical model is developed that assumes the transient jet can be characterized as a spherical vortex interacting with a steady-state jet. The model demonstrates that the ratio of nozzle radius to jet velocity defines a time constant that uniquely characterizes the behavior and similarity of impulsively started incompressible turbulent jets.

  13. Ram-jet Performance

    NASA Technical Reports Server (NTRS)

    Cervenko, A. J.; Friedman, R.

    1956-01-01

    The ram jet is basically one of the most dimple types of aircraft engine. It consists only of an inlet diffuser, a combustion system, and an exit nozzle. A typical ram-jet configuration is shown in figure 128. The engine operates on the Brayton cycle, and ideal cycle efficiency depends only on the ratio of engine to ambient pressure. The increased, engine pressures are obtained by ram action alone, and for this reason the ram jet has zero thrust at zero speed. Therefore, ram-jet-powered aircraft must be boosted to flight speeds close to a Mach number of 1.0 before appreciable thrust is generated by the engine. Since pressure increases are obtained by ram action alone, combustor-inlet pressures and temperatures are controlled by the flight speed, the ambient atmospheric condition, and by the efficiency of the inlet diffuser. These pressures and temperatures, as functions of flight speed and altitude, are shown in figure 129 for the NACA standard atmosphere and for practical values of diffuser efficiency. It can be seen that very wide ranges of combustor-inlet temperatures and pressures may be encountered over the ranges of flight velocity and altitude at which ram jets may be operated. Combustor-inlet temperatures from 500 degrees to 1500 degrees R and inlet pressures from 5 to 100 pounds per square inch absolute represent the approximate ranges of interest in current combustor development work. Since the ram jet has no moving parts in the combustor outlet, higher exhaust-gas temperatures than those used in current turbojets are permissible. Therefore, fuel-air ratios equivalent to maximum rates of air specific impulse or heat release can be used, and, for hydrocarbon fuels, this weight ratio is about 0.070. Lower fuel-air ratios down to about 0.015 may also be required to permit efficient cruise operation. This fuel-air-ratio range of 0.015 to 0.070 used in ram jets can be compared with the fuel-air ratios up to 0.025 encountered in current turbojets. Ram-jet

  14. The Twin Jet Nebula

    NASA Technical Reports Server (NTRS)

    1997-01-01

    M2-9 is a striking example of a 'butterfly' or a bipolar planetary nebula. Another more revealing name might be the 'Twin Jet Nebula.' If the nebula is sliced across the star, each side of it appears much like a pair of exhausts from jet engines. Indeed, because of the nebula's shape and the measured velocity of the gas, in excess of 200 miles per second, astronomers believe that the description as a super-super-sonic jet exhaust is quite apt. This is much the same process that takes place in a jet engine: The burning and expanding gases are deflected by the engine walls through a nozzle to form long, collimated jets of hot air at high speeds. M2-9 is 2,100 light-years away in the constellation Ophiucus. The observation was taken Aug. 2, 1997 by the Hubble telescope's Wide Field and Planetary Camera 2. In this image, neutral oxygen is shown in red, once-ionized nitrogen in green, and twice-ionized oxygen in blue.

  15. Jet penetration in glass

    SciTech Connect

    Moran, B.; Glenn, L.A.; Kusubov, A.

    1991-05-01

    We describe a phenomenological model which accounts for the mechanical response of glass to intense impulsive loading. An important aspect of this response is the dilatancy accompanying fracture. We have also conducted a number of experiments with 38.1-mm diameter precision shaped charges to establish the performance against various targets and to allow evaluation of our model. At 3 charge diameters standoff, the data indicate that both virgin and damaged glass offer better (Bernoulli-scaled) resistance to penetration than either of 4340 steel, or 6061-T6 aluminum alloy. Time-resolved measurements indicate two distinct phases of jet penetration in glass: An initial hydrodynamic phase, and a second phase characterized by a slower penetration velocity. Our calculations show that at early time, a crater is formed around the jet and only the tip of the undisturbed jet interacts with the glass. At late time the glass has collapsed on the jet and degraded penetration continues via a disturbed and fragmented jet.

  16. Sweeping Jet Optimization Studies

    NASA Technical Reports Server (NTRS)

    Melton, LaTunia Pack; Koklu, Mehti; Andino, Marlyn; Lin, John C.; Edelman, Louis

    2016-01-01

    Progress on experimental efforts to optimize sweeping jet actuators for active flow control (AFC) applications with large adverse pressure gradients is reported. Three sweeping jet actuator configurations, with the same orifice size but di?erent internal geometries, were installed on the flap shoulder of an unswept, NACA 0015 semi-span wing to investigate how the output produced by a sweeping jet interacts with the separated flow and the mechanisms by which the flow separation is controlled. For this experiment, the flow separation was generated by deflecting the wing's 30% chord trailing edge flap to produce an adverse pressure gradient. Steady and unsteady pressure data, Particle Image Velocimetry data, and force and moment data were acquired to assess the performance of the three actuator configurations. The actuator with the largest jet deflection angle, at the pressure ratios investigated, was the most efficient at controlling flow separation on the flap of the model. Oil flow visualization studies revealed that the flow field controlled by the sweeping jets was more three-dimensional than expected. The results presented also show that the actuator spacing was appropriate for the pressure ratios examined.

  17. B-jets and z + b-jets at CDF

    SciTech Connect

    Jeans, Daniel; /Rome U.

    2006-06-01

    The authors present CDF cross-section measurements for the inclusive production of b jets and the production of b jets in association with a Z{sup 0} boson. Both measurements are in reasonable agreement with NLO QCD predictions.

  18. Aeroacoustic Experiments with Twin Jets

    NASA Technical Reports Server (NTRS)

    Bozak, Richard F.; Henderson, Brenda S.

    2012-01-01

    While the noise produced by a single jet is azimuthally symmetric, multiple jets produce azimuthally varying far-field noise. The ability of one jet to shield another reduces the noise radiated in the plane of the jets, while often increasing the noise radiated out of the plane containing the jets. The present study investigates the shielding potential of twin jet configurations over subsonic and over-expanded supersonic jet conditions with simulated forward flight. The experiments were conducted with 2 in. throat diameter nozzles at four jet spacings from 2.6d to 5.5d in center-to-center distance, where d is the nozzle throat diameter. The current study found a maximum of 3 dB reduction in overall sound pressure level relative to two incoherent jets in the peak jet noise direction in the plane containing the jets. However, an increase of 3 dB was found perpendicular to the plane containing the jets. In the sideline direction, shielding is observed for all jet spacings in this study.

  19. New Evidence from Silica Debris Exo-Systems for Planet Building Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Lisse, Carey

    2010-05-01

    There is abundant inferential evidence for massive collisions in the early solar system [1]: Mercury's high density; Venus' retrograde spin; Earth's Moon; Mars' North/South hemispherical cratering anisotropy; Vesta's igneous origin [2]; brecciation in meteorites [3]; and Uranus' spin axis located near the plane of the ecliptic. Recent work [4] analyzing Spitzer mid-IR spectra has demonstrated the presence of large amounts of amorphous silica and SiO gas produced by a recent (within 103 - 104 yrs) large (MExcess > MPluto) hypervelocity impact collision around the young (~12 Myr old) nearby star HD172555, at the right age to form rocky planets. Many questions still remain concerning the location, lifetime, and source of the detected silica/SiO gas, which should not be stable in orbit at the estimated 5.8 AU from the HD172555 A5V primary for more than a few decades, yet it is also highly unlikely that we are fortuitously observing these systems immediately after silica formation A tabulation of the amount counts in the fine silica dust is decidedly Fe and Mg-atom poor compared to solar [4]. Three possible origins for the observed silica/SiO gas seem currently plausible : (1) A single hyperevelocity impact (>10km/s in order to produce silica and vaporize SiO at impact) creating an optically thick circumplanetary debris ring which is overflowing or releasing silica-rich material from its Hill sphere. Like terrestrial tektites, the Fe/Mg poor amorphous silica rubble is formed from quick-quenched molten/vaporized rock created during the impact. The amount of dust detected in the HD172555 system is easily enough to fill and overflow the Hill sphere radius of 0.03 AU for a Pluto-sized body at 5.8 AU from an A5 star, unless it is optically thick (> 1 cm in physical depth). Such a disk would provide a substantial fraction of the observed IR flux, and will be dense enough to self-shield its SiO gas, greatly extending its photolytic lifetime. The lifetime for such a system

  20. Renewable jet fuel.

    PubMed

    Kallio, Pauli; Pásztor, András; Akhtar, M Kalim; Jones, Patrik R

    2014-04-01

    Novel strategies for sustainable replacement of finite fossil fuels are intensely pursued in fundamental research, applied science and industry. In the case of jet fuels used in gas-turbine engine aircrafts, the production and use of synthetic bio-derived kerosenes are advancing rapidly. Microbial biotechnology could potentially also be used to complement the renewable production of jet fuel, as demonstrated by the production of bioethanol and biodiesel for piston engine vehicles. Engineered microbial biosynthesis of medium chain length alkanes, which constitute the major fraction of petroleum-based jet fuels, was recently demonstrated. Although efficiencies currently are far from that needed for commercial application, this discovery has spurred research towards future production platforms using both fermentative and direct photobiological routes. PMID:24679258