Science.gov

Sample records for hypervelocity metal jets

  1. Plasma jet acceleration of dust particles to hypervelocities

    SciTech Connect

    Ticos, C. M.; Wang, Zhehui; Wurden, G. A.; Kline, J. L.; Montgomery, D. S.

    2008-10-15

    A convenient method to accelerate simultaneously hundreds of micron-size dust particles to a few km/s over a distance of about 1 m is based on plasma drag. Plasma jets which can deliver sufficient momentum to the dust particles need to have speeds of at least several tens of km/s, densities of the order of 10{sup 22} m{sup -3} or higher, and low temperature {approx}1 eV, in order to prevent dust destruction. An experimental demonstration of dust particles acceleration to hypervelocities by plasma produced in a coaxial gun is presented here. The plasma flow speed is deduced from photodiode signals while the plasma density is measured by streaked spectroscopy. As a result of the interaction with the plasma jet, the dust grains are also heated to high temperatures and emit visible light. A hypervelocity dust shower is imaged in situ with a high speed video camera at some distance from the coaxial gun, where light emission from the plasma flow is less intense. The bright traces of the flying microparticles are used to infer their speed and acceleration by employing the time-of-flight technique. A simple model for plasma drag which accounts for ion collection on the grain surface gives predictions for dust accelerations which are in good agreement with the experimental observations.

  2. 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.

  3. 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.

  4. Hypervelocity impact on silicon wafers with metallic and polymeric coatings

    NASA Astrophysics Data System (ADS)

    Taylor, E. A.; Scott, H. J.; Abraham, M.; Kearsley, A. T.

    2001-10-01

    Current and near future developments in microsystem technologies (MST, also known as MEMS) are defining a new trend towards lower mass, smaller volume spacecraft, without loss of functionality. The MST spacecraft components are etched onto silicon wafers coated with different metallic or polymeric material layers (typically 1-2 microns in thickness). These silicon wafers are then integrated to provide the spacecraft structure subsystem. For the majority of spacecraft, small debris and meteoroid impacts are not often able to cause large satellite platform failures, due to the shielding provided by existing structural and thermal materials and the high percentage of 'empty volume' contained within a typical spacecraft structure. Smaller satellites incorporating MST and based on silicon wafers, whilst presenting a smaller surface area, are expected to be vulnerable to impacts as the lower subsystem mass defines a less substantial structure, providing significantly less protection against impact. This paper presents results of a BNSC-funded study aimed at identifying the vulnerability of MST technologies based on silicon wafers to space debris and meteoroid impact. Hypervelocity impact tests were carried out on silicon wafers coated with five different types of deposited material. Multiple glass spheres were fired simultaneously at velocities in the range of 6 km/s. The impact results identify the hypervelocity impact response of the silicon wafers. The impacted targets showed a brittle material damage morphology (defined by fracture) and linked to the crystalline structure of the silicon wafer. As predicted from the mechanical properties, it was found that the silicon tended to fracture along the 111 planes. Cross-sectioned craters also showed the crystalline structure of the silicon, with the onset of fracture-driven spall on the rear surface. The metal and polymeric coatings produced diverse damage morphologies, with delamination zones being up to twice the diameter

  5. 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.

  6. 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.

  7. Study of hypervelocity projectile impact on thick metal plates

    DOE PAGES

    Roy, Shawoon K.; Trabia, Mohamed; O’Toole, Brendan; ...

    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

  8. Chemical fractionation resulting from the hypervelocity impact process on metallic targets

    NASA Astrophysics Data System (ADS)

    Libourel, Guy; Ganino, Clément; Michel, Patrick; Nakamura, Akiko

    2016-10-01

    In a regime of hypervelocity impact cratering, the internal energy deposited in target + projectile region is large enough to melt and/or vaporize part of the material involved, which expands rapidly away from the impact site. Fast and energetic impact processes have therefore important chemical consequences on the projectile and target rock transformations during major impact events. Several physical and chemical processes occurred indeed in the short duration of the impact, e.g., melting, coating, mixing, condensation, crystallization, redox reactions, quenching, etc., all concurring to alter both projectile and target composition on the irreversible way.In order to document such hypervelocity impact chemical fractionation, we have started a program of impact experiments by shooting doped (27 trace elements) millimeter-sized basalt projectiles on metallic target using a two stages light gas gun. With impact velocity in the range from 0.25 to 7 km.s-1, these experiments are aimed i) to characterize chemically and texturally all the post-mortem materials (e.g., target, crater, impact melt, condensates, and ejectas), in order ii) to make a chemical mass balance budget of the process, and iii) to relate it to the kinetic energy involved in the hypervelocity impacts for scaling law purpose. Irrespective of the incident velocities, our preliminary results show the importance of redox processes, the significant changes in the ejecta composition (e.g., iron enrichment) and the systematic coating of the crater by the impact melt [1]. On the target side, characterizations of the microstructure of the shocked iron alloys to better constrain the shielding processes. We also show how these results have great implications in our understanding on the current surface properties of small bodies, and chiefly in the case of M-type asteroids. [1] Ganino C, Libourel G, Nakamura AM & Michel P (2015) Goldschmidt Abstracts, 2015 990.

  9. Jet-printed copper metallization

    NASA Astrophysics Data System (ADS)

    Hong, Cheong Min

    Macroelectronics is a technology for making electronic circuits over very large areas at low cost. Flat panel displays, sensor arrays, and thin film solar cells are examples of macroelectronics. Crucial to the success of this new technology is the development of inexpensive electronic processes, materials, and devices. Direct printing techniques, which eliminate processing steps and save device and process materials, are the key to high volume and high throughput manufacturing. Copper metallization has been receiving increasing attention in both microelectronics and macroelectronics. Copper has high conductivity, density, melting point, heat capacity, and thermal conductivity. However, copper is also hard to dry etch. For these reasons we have developed and demonstrated a directly printed copper source/drain metallization technique and applied it to the fabrication of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs). The maximum process temperature of 200°C is compatible with conventional active matrix liquid crystal display (AMLCD) technology. In this dissertation, we show the process of depositing copper films by jet printing. We discuss the preparation and the properties of the copper precursor material used in the jet printing. We survey the conversion process from copper precursor to copper under varying processing conditions. The resulting copper film is probed for its physical, electrical, and mechanical properties. To demonstrate the feasibility of the jet printing technique, we print copper source/drain contacts for a-Si:H TFTs. The photolithography-free TFT fabrication process uses the printed xerographic toner technique developed earlier in this laboratory. We show that functional TFTs can be made with printed copper source and drain contacts. The jet printing of copper contacts represents a further step toward an all-printed thin film transistor technology.

  10. 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.

  11. Plastic Deformation and Perforation of Metal using Metallic Jet

    NASA Astrophysics Data System (ADS)

    Sarkar, Partha; Chaturvedi, Shashank; Shyam, Anurag; Kumar, Rajesh; Lathi, Deepak; Chaudhari, Vilas; Verma, Rishi; Sonara, Jaswant; Shah, Kunal; Adhikary, Biswajit

    2002-12-01

    Pulsed underwater electrical discharges have been used in the past to generate pressures of the order of several tens of kilobars, for applications such as rock fragmentation and metallic jet production. Preliminary results for a metallic jet system have been reported earlier. A modified design for a metallic jet production system is reported here. With this arrangement, we are able to perforate 11 mm thick aluminium sheet. Such a system, at higher energy levels, could be used for oil and gas well perforation.

  12. 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.

  13. 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.

  14. 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.

  15. Metal Injection Molding for Superalloy Jet Engine Components

    DTIC Science & Technology

    2006-05-01

    RTO-MP-AVT-139 9 - 1 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED Metal Injection Molding for Superalloy Jet Engine...muc.mtu.de METAL INJECTION MOLDING FOR SUPERALLOY JET ENGINE COMPONENTS The Metal Injection Molding [MIM] process is a combination of powder...firearms and medical. MTU Aero Engines GmbH advanced the MIM process using high temperature superalloys powders. Optimized thermal processes and

  16. An analytical and experimental study of the behavior of semi-infinite metal targets under hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Chakrapani, B.; Rand, J. L.

    1971-01-01

    The material strength and strain rate effects associated with the hypervelocity impact problem were considered. A yield criterion involving the second and third invariants of the stress deviator and a strain rate sensitive constitutive equation were developed. The part of total deformation which represents change in shape is attributable to the stress deviator. Constitutive equation is a means for analytically describing the mechanical response of a continuum under study. The accuracy of the yield criterion was verified utilizing the published two and three dimensional experimental data. The constants associated with the constitutive equation were determined from one dimensional quasistatic and dynamic experiments. Hypervelocity impact experiments were conducted on semi-infinite targets of 1100 aluminum, 6061 aluminum alloy, mild steel, and commercially pure lead using spherically shaped and normally incident pyrex projectiles.

  17. Nearby Low-Mass Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Q.; Smith, M. C.; Carlin, J. L.

    2014-07-01

    Hypervelocity stars are those that have speeds exceeding the escape speed and are hence unbound from the Milky Way. We investigate a sample of low-mass hypervelocity candidates obtained using data from the high-precision SDSS Stripe 82 catalogue, which we have combined with spectroscopy from the 200-inch Hale Telescope at Palomar Observatory. We find four good candidates, but without metallicities it is difficult to pin-down their distances and therefore total velocities. Our best candidate has a significant likelihood that it is escaping the Milky Way for a wide-range of metallicities.

  18. 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).

  19. Powdered Metal Sintering of Jet Vanes.

    DTIC Science & Technology

    1982-02-01

    Following the infiltration process, the excess copper at the base of the part is removed mechanically with final clean-up by immersion in dilute nitric...The motor was a low-cost controllable booster (LCCB) that could use jet vane control. Nominal performance for the nonaluminized HTPB propellant ... HTPB propellant . Total impulse was approximately twice that of the motor in Test No. 1. Burn time was 8.5 seconds and average thrust was 14,000 pounds

  20. 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.; Nicholson, Leonard S. (Technical Monitor)

    1999-01-01

    Results of arc-jet tests conducted at the NASA Johnson Space Center (JSC) on Reinforced Carbon-Carbon (RCC) samples subjected to hypervelocity impact are presented. The RCC test specimens are representative of RCC component used on the Space Shuttle Orbiter. The objective of the arc jet testing was to establish the oxidation characteristics of RCC when hypervelocity projectiles, simulating meteoroid/orbital debris (MOD), impact the RCC material. In addition, analytical modeling of the increased material oxidation in the impacted area, using measured hole growth data, to develop correlations for use in trajectory simulations is also discussed.

  1. Impulsive control for hypervelocity missiles

    NASA Astrophysics Data System (ADS)

    Magness, R. W.

    1981-05-01

    A hypervelocity agile interceptor/quickshot is being developed for defense of ballistic missile launch sites. A guidance and control system is required to achieve the missile guidance accuracy necessary for direct target impact. Attitude control systems evaluated for the agile interceptor included aerodynamic controls, thrust vector controls and impulsive motor controls. The solid squib impulsive control motion was selected because of high response rate, low weight and low volume. A baseline motor configuration was designed and a solid propellant squib was developed for use in the control system. Ballistic pendulum and bench tests were conducted with a test impulsive control motor to measure nominal performance, establish the standard deviation of performance, and define requirements to prevent sympathetic ignition. A dynamic control wind tunnel test was also conducted to determine the impulse augmentation due to the impulsive motor jet interaction with the missile boundary layer. The degree and direction of augmentation was measured for variations in Mach number and angle of attack.

  2. Thermal Interaction Between Molten Metal Jet and Sodium Pool: Effect of Principal Factors Governing Fragmentation of the Jet

    SciTech Connect

    Nishimura, Satoshi; Kinoshita, Izumi; Sugiyama, Ken-Ichiro; Ueda, Nobuyuki

    2005-02-15

    To clarify the effects of the principal factors that govern the thermal fragmentation of a molten metallic fuel jet in the course of fuel-coolant interaction, which is important in evaluating the sequence of core disruptive accidents (CDAs) for metallic fuel fast reactors, basic experiments were carried out using molten metallic fuel simulants (copper and silver) and a sodium pool.Fragmentation of a molten metal jet with a solid crust was caused by internal pressure produced by the boiling of sodium, which is locally entrapped inside the jet due to hydrodynamic motion between the jet and the coolant. The superheating and the latent heat of fusion of the jet are the principal factors governing this type of thermal fragmentation. On the other hand, the effect of the initial sodium temperature is regarded as negligible in the case of thermal conditions expected to result in CDAs for practical metallic fuel cores. Based on the fragmentation data for several kinds of jets (Cu, Ag, SUS, U, and U-5 wt% Zr alloy), an empirical correlation is proposed that is applicable to the calculation of a mass median diameter of fragments produced by the thermal fragmentation of the jet with a solid crust under low ambient Weber number conditions.

  3. Hypervelocity impact cratering calculations

    NASA Technical Reports Server (NTRS)

    Maxwell, D. E.; Moises, H.

    1971-01-01

    A summary is presented of prediction calculations on the mechanisms involved in hypervelocity impact cratering and response of earth media. Considered are: (1) a one-gram lithium-magnesium alloys impacting basalt normally at 6.4 km/sec, and (2) a large terrestrial impact corresponding to that of Sierra Madera.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  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 phenomena

    SciTech Connect

    Chhabildas, L.C.

    1995-07-01

    There is a need to determine the equations of state of materials in regimes of extreme high pressures, temperatures and strain rates that are not attainable on current two-stage light-gas guns. Understanding high-pressure material behavior is crucial to address the physical processes associated with a variety of hypervelocity impact events related to space sciences-orbital-debris impact, debris-shield designs, high-speed plasma propagation, and impact lethality applications. At very high impact velocities material properties will be dominated by phase-changes, such as melting or vaporization, which cannot be achieved at lower impact velocities. Development of well-controlled and repeatable hypervelocity launch capabilities is the first step necessary to improve our understanding of material behavior at extreme pressures and temperatures not currently available using conventional two-stage light-gas gun techniques. In this paper, techniques that have been used to extend both the launch capabilities of a two-stage light gas gun to 16 km/s, and their use to determine the material properties at pressures and temperature states higher than those ever obtained in the laboratory are summarized. The newly developed hypervelocity launcher (HVL) can launch intact (macroscopic dimensions) plates to 16 km/s. Time-resolved interferometric techniques have been used to determine shock-loading/release characteristics of materials impacted by such fliers as well as shock-induced vaporization phenomena in fully vaporized states. High-speed photography or radiography has been used to evaluate the debris propagation characteristics resulting from disc impact of thin bumper sheets at hypervelocities in excess of 10 km/s using the HVL. Examples of these experiments are provided in this paper.

  10. 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.

  11. 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.

  12. Analysis of impingement heat transfer for two parallel liquid-metal slot jets

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1974-01-01

    An analytical method is developed for determining heat transfer by impinging liquid-metal slot jets. The method involves mapping the jet flow region, which is bounded by free streamlines, into a potential plane where it becomes a uniform flow in a channel of constant width. The energy equation is transformed into potential plane coordinates and is solved in the channel flow region. Conformal mapping is then used to transform the solution back into the physical plane and obtain the desired heat-transfer characteristics. The analysis given here determines the heat-transfer characteristics for two parallel liquid-metal slot jets impinging normally against a uniformly heated flat plate. The liquid-metal assumptions are made that the jets are inviscid and that molecular conduction is dominating heat diffusion. Wall temperature distributions along the heated plate are obtained as a function of spacing between the jets and the jet Peclet number.

  13. Rapid prototyping with lasers using metal powder jets

    NASA Astrophysics Data System (ADS)

    Liedl, Gerhard; Schuoecker, D.; Kny, E.

    2003-09-01

    Rapid Prototyping is an important part of modern development sequences, where a variety of solutions is available nowadays, ranging from ultrafast machining via casting technologies, laminated objects manufacturing, also with lasers, to stereolithography and laser sintering. Most of these processes suffer from certain restrictions, either in terms of raw material, geometry or quality of the finished workpiece. In particular, laser sintering leads to structures with a low density that reduces the strength of the part considerably. Since the individual powder particles are only molten at their surface and adhere thus to each other, only in small regions of the surface leaving the majority of the grain mass unmolten and resulting in a faint lattice that must be filled with an additional material to reach the necessary strength. A different solution offers the Blown Powder Process, where a jet of e.g. metal powder is directed towards the surface of the workpiece in the focus of a laser beam, thus melting each metal particle totally and producing practically molten droplets that settle on the momentary surface of the workpiece, thus being welded to the latter. Since all the material delivered to the workpiece is perfectly molten and resolidified, very dense structures with a high strength comparable to the strength of the initial unpowderized material are obtained, as experiments carried out by the authors with differed powderized materials have shown. It has also been demonstrated that the latter process can be used to generate nearly arbitrary 3D geometry. A lot of effort has been invested by the authors to avoid the influence of the direction of the necessary relative motion between laser, powder jet and workpiece and also to reduce the roughness of the surface generated by the actual process. Further experimental investigations will be devoted to the clarification of the range of materials, where the actual process can be applied and to the generation of practical

  14. 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.

  15. Assessment of ink jet technology for micro-dispensing of metal particle-bearing fluids

    SciTech Connect

    Lowe, T.C.

    1988-05-01

    Ink jet printing technology is explored as a means for precisely depositing metal-bearing fluids on porous and nonporous substrates. Several inks were formulated and evaluated in related, but separate, ink jet experiments. Alternative ink jet hardware configurations were examined to show the influence of ink jet system parameters on droplet formation and system reliability. The experiments successfully demonstrated the feasibility of generating metal-bearing ink droplets with velocities less than 1 m/s and diameters as small as 28 micrometers. 3 refs., 6 figs., 8 tabs.

  16. Hypervelocity Orbital Intercept Guidance

    DTIC Science & Technology

    1988-04-14

    Professor Charles E. Fosha, Jr. Terminal guidance of a hypervelocity exo-atmospheric orbital interceptor with free end-time is examined. The pursuer is...stochastic nonlinear systems with free end-time was developed by Tse and 29 Bar-Shalom [5]. This method differs from the optimal control formulation...Vol. AC-18, No. 2, April 1973, pp. 98-108. 5. Tse, E., and Y. Bar-Shalom, "Adaptive Dual Control For Stochastic Nonlinear Systems with Free End- Time

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Analysis of liquid-metal-jet impingement cooling in a corner region and for a row of jets

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1975-01-01

    A conformal mapping method was used to analyze liquid-metal-jet impingement heat transfer. The jet flow region and energy equation are transformed to correspond to uniform flow in a parallel plate channel with nonuniform heat addition along a portion of one wall. The exact solution for the wall-temperature distribution was obtained in the transformed channel, and the results are mapped back into the physical plane. Two geometries are analyzed. One is for a single slot jet directed either into an interior corner formed by two flat plates, or over the external sides of the corner; the flat plates are uniformly heated, and the corner can have various included angles. The heat-transfer coefficient at the stagnation point at the apex of the plates is obtained as a function of the corner angle, and temperature distributions are calculated along the heated walls. The second geometry is an infinite row of uniformly spaced parallel slot jets impinging normally against a uniformly heated plate. The heat-transfer behavior is obtained as a function of the spacing between the jets. Results are given for several jet Peclet numbers from 5 to 50.

  2. 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.

  3. 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.

  4. Hypervelocity Impacts - Shape-dependant Effects

    NASA Astrophysics Data System (ADS)

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

    physics of hypervelocity impacts of shaped projectiles. As a major topic in this paper, an approach on how to cope with the impactor shape in ballistic limit equations used for metallic Whipple shields is presented. A preliminary ballistic limit equation, giving the critical projectile mass for ellipsoid-shaped projectiles is derived from existing and thoroughly verified BL equations for spherical projectiles on metallic Whipple shields and calibrated and validated through experimental and numerical simulation results. This equation is compared to published data on shape effects in hypervelocity impact research. The derived ballistic limit equation that is provided in this paper can be used to predict the critical projectile mass for a given projectile shape for normal and unyawed impact on metallic Whipple Shield as a function of impact velocity.

  5. 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.

  6. 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.

  7. 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.

  8. Optical observation of metal jet generated by high speed inclined collision

    NASA Astrophysics Data System (ADS)

    Mori, A.; Tanaka, S.; Hokamoto, K.

    2017-02-01

    Explosive welding, one of the high energy rate material processing, is known the technique to weld strongly for the dissimilar metal combinations. When a metal is collided to the other metal at high velocity with a certain angle, good welding is achieved in this technique. Important parameters of the explosive welding method are the collision velocity and the collision angle. And it is necessary to know these parameters to obtain the explosively welded materials of several metals combinations. However, the optical observation for the collision of metal plate accelerated by the explosive is difficult because of the obstruction by the spreading of detonation gas. In the present work a single-stage powder gun and high speed video camera were used to observe the inclined collision of metals at the high velocity. Projectile consisted by a metal disc and sabot was accelerated by the deflagration of a gunpowder and was collided to another metal disc set with a certain angle. Metal jet was generated at the collision point when the projectile was collided to the target disc in the range of suitable conditions. By using this observation system, a series of the flow from the high speed collision to the generation of metal jet could be taken photographs clearly. This investigation shows the experimental results of the similar and dissimilar metal collision, with comparing the visualization of a metal jet simulated numerically.

  9. Hypervelocity stars from young stellar clusters in the Galactic Centre

    NASA Astrophysics Data System (ADS)

    Fragione, G.; Capuzzo-Dolcetta, R.; Kroupa, P.

    2017-01-01

    The enormous velocities of the so called hypervelocity stars (HVSs) derive, likely, from close interactions with massive black holes, binary stars encounters or supernova explosions. In this paper, we investigate the origin of hypervelocity stars as consequence of the close interaction between the Milky Way central massive black hole and a passing-by young stellar cluster. We found that both single and binary HVSs may be generated in a burst-like event, as the cluster passes near the orbital pericentre. High velocity stars will move close to the initial cluster orbital plane and in the direction of the cluster orbital motion at the pericentre. The binary fraction of these HVS jets depends on the primordial binary fraction in the young cluster. The level of initial mass segregation determines the value of the average mass of the ejected stars. Some binary stars will merge, continuing their travel across and out of the Galaxy as blue stragglers.

  10. 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.

  11. Jets.

    PubMed

    Rhines, Peter B.

    1994-06-01

    This is a discussion of concentrated large-scale flows in planetary atmospheres and oceans, argued from the viewpoint of basic geophysical fluid dynamics. We give several elementary examples in which these flows form jets on rotating spheres. Jet formation occurs under a variety of circumstances: when flows driven by external stress have a rigid boundary which can balance the Coriolis force, and at which further concentration can be caused by the beta effect; when there are singular lines like the line of vanishing windstress or windstress-curl, or the Equator; when compact sources of momentum, heat or mass radiate jet-like beta plumes along latitude circles; when random external stirring of the fluid becomes organized by the beta effect into jets; when internal instability of the mass field generates zonal flow which then is concentrated into jets; when bottom topographic obstacles radiate jets, and when frontogenesis leads to shallow jet formation. Essential to the process of jet formation in stratified fluids is the baroclinic life cycle described in geostrophic turbulence studies; there, conversion from potential to kinetic energy generates eddy motions, and these convert to quasibarotropic motions which then radiate and induce jet-like large-scale circulation. Ideas of potential vorticity stirring by eddies generalize the notion of Rossby-wave radiation, showing how jets embedded in an ambient potential vorticity gradient (typically due to the spherical geometry of the rotating planet) gain eastward momentum while promoting broader, weaker westward circulation. Homogenization of potential vorticity is an important limit point, which many geophysical circulations achieve. This well-mixed state is found in subdomains of the terrestrial midlatitude oceans, the high-latitude circumpolar ocean, and episodically in the middle atmosphere. Homogenization expels potential vorticity gradients vertically to the top and bottom of the fluid, and sideways to the edges of

  12. Hypervelocity impact testing of tethers

    NASA Technical Reports Server (NTRS)

    Woodis, William R.; Tallentire, Francis I.

    1988-01-01

    An experimental test program has been conducted to ascertain the strength losses to which representative space tether materials may be prone upon impact by hypervelocity particles of known size, density, and velocity, when the tether is under tensile loading typical of flight design loads. Twelve hypervelocity impacts were followed by tensile tests to failure to determine residual strength; relationships are established between particle velocity and strength loss due to impact damage, as well as between tether strength loss and the relationship between particle and tether diameters. Tentative design criteria are formulated in terms of a design factor allowing for strength degradation by impact.

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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 ˜1012 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.

  16. Dynamics of liquid metal droplets and jets influenced by a strong axial magnetic field

    NASA Astrophysics Data System (ADS)

    Hernández, D.; Karcher, Ch

    2017-07-01

    Non-contact electromagnetic control and shaping of liquid metal free surfaces is crucial in a number of high-temperature metallurgical processes like levitation melting and electromagnetic sealing, among others. Other examples are the electromagnetic bending or stabilization of liquid metal jets that frequently occur in casting or fusion applications. Within this context, we experimentally study the influence of strong axial magnetic fields on the dynamics of falling metal droplets and liquid metal jets. GaInSn in eutectic composition is used as test melt being liquid at room temperature. In the experiments, we use a cryogen-free superconducting magnet (CFM) providing steady homogeneous fields of up to 5 T and allowing a tilt angle between the falling melt and the magnet axis. We vary the magnetic flux density, the tilt angle, the liquid metal flow rate, and the diameter and material of the nozzle (electrically conducting/insulating). Hence, the experiments cover a parameter range of Hartmann numbers Ha, Reynolds numbers Re, and Weber numbers We within 0 < Ha < 440, 340 < Re < 4500, and 0.09 < We < 12.1. As major results we find that under the influence of the strong magnetic field, droplet rotation ceases and the droplets are stretched in the field direction. Moreover, we observe that the jet breakup into droplets (spheroidization) is suppressed, and in the case of electrically conducting nozzles and tilt, the jets are bent towards the field axis.

  17. 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.

  18. 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.

  19. 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.

  20. High heat flux accelerator targets cooling with liquid-metal jet impingement

    NASA Astrophysics Data System (ADS)

    Silverman, I.; Arenshtam, A.; Kijel, D.; Nagler, A.

    2005-12-01

    Accelerator targets for radioisotope production generate very high density of thermal energy in the target material, which absorbs the particles beam. The design of these targets requires efficient heat removal techniques in order to preserve the integrity of the target. Normal average heat fluxes from these targets are around 1 kW/cm2 and may reach order of magnitude higher values at hot spots. Few techniques exist to deal with such high heat fluxes. One of them is jet impingement that has been proved to be able to deal with heat fluxes as high as 40 kW/cm2 using water as coolant. However, this requires very high jet velocities of more than 100 m/s. A few theoretical and experimental studies indicate that liquid-metal coolants (e.g., gallium or gallium alloys) can improve the heat transfer efficiency in this configuration. Experimental cooling loops based on water and liquid-metal jet impingement have been designed and built at Soreq to evaluate this method. For the current liquid-metal system an eutectic alloy of gallium and indium (GaIn) is used. Initial experiments demonstrate that the GaIn cooling system can deal with heat flux of about 2 kW/cm2 over an area of 1 cm2. The jet velocity is less than 4 m/s and the required differential pressure from the pump is less than 1 bar.

  1. Flow of a Two-Dimensional Liquid Metal Jet in a Strong Magnetic Field

    NASA Astrophysics Data System (ADS)

    Molokov, S.; Reed, C. B.

    2002-01-01

    A combined effect of surface tension, gravity, inertia and a transverse nonuniform magnetic field on the steady, two-dimensional jet (or curtain) flow is studied with reference to liquid metal divertors of tokamaks and coating flows. Here main fundamental aspects of the flow are presented. More details on the assumptions, analysis and results are given in. Consider a steady flow of a viscous, electrically conducting, incompressible fluid in a jet pouring downward in the x-asterisk-direction (the direction of gravity) from a nozzle.

  2. 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.

  3. 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.

  4. 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.

  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 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.

  7. Hypervelocity Technology (HVT) crew escape

    NASA Technical Reports Server (NTRS)

    Jines, Lanny A.

    1987-01-01

    Conceptual designs are being investigated for escape systems applicable to hypervelocity technology class aerospace vehicles. The concepts selected for further development will provide survivable escape and recovery throughout all phases of flight. Sixteen conceptual escape systems were identified, of which two were viable. The study vehicles included a horizontally launched vehicle (HLV) and a vertically launched vehicle (VLV). Computer-aided design models of the candidate escape systems were developed. State-of-the-art or near-term enabling technologies were identified in such areas as propulsion, life support, thermal protection, and deceleration.

  8. 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.

  9. 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.

  10. Determination of a Jet Fuel Metal Deactivator by High Performance Liquid Chromatography

    DTIC Science & Technology

    1983-06-01

    column packings, and sensitive low dead volume detectors have catapulted HPLC into a rapidly maturing and valuable complement to gas chromatography ...be a gas or liquid; and a stationary phase, which may be either a liquid or a solid. The form of chromatography used in this research was partition...AFWAL-TR-82-21 28 1 1- 0 • DETERMINATION OF A JET FUEL METAL DEACTIVATOR BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY Paul C. Hayes, Jr. Fuels Branch

  11. A study of heat transfer in the surface layer of metal during the impingement of a liquid jet

    NASA Astrophysics Data System (ADS)

    Koldin, A. V.; Platonov, N. I.

    2008-03-01

    We propose a model of heat transfer that takes place when a sheet of metal heated to a high temperature is cooled by a jet. The model takes into account transition and film boiling of liquid, as well as convective and radiant heat transfer in air medium. Examples are given illustrating how the temperature field of a movable metal sheet cooled by a system of jets is calculated.

  12. 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%.

  13. Alloys formation upon hypervelocity impacts

    NASA Astrophysics Data System (ADS)

    Mandeville, J. C.; Perrin, J. M.; Vidal, L.; Vidal, A.

    Satellite materials exposed to the space environment are indeed valuable detectors for cosmic and man-made solid particles Many investigations have been made to deduce the geometric size shape and dynamic incidence angle parameters of these projectiles from the morphology of the impact features Furthermore the chemical analysis of remnants when they are found inside craters can provide valuable information about the nature and the origin of these particles However interpretation difficulties have made necessary laboratory hypervelocity impact tests A number of impacts with well defined angles of incidence and velocities using calibrated projectiles have been performed on various targets Alloys obviously formed from projectile and targets components are found We have studied the links between the morphologies the physical and chemical properties of these alloys and those of the incident particles and the targets When projectiles and targets are made of pure materials such as in laboratory tests we have found a clear connection between the composition of the alloys and the kinetic energy of the projectiles Explanations using phase diagrams are given An extrapolation to complex materials such as those used in solar arrays is presented Further modelling of the alloys formation upon hypervelocity impacts is proposed

  14. 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.

  15. The effect of a metal wall on confinement in JET and ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Beurskens, M. N. A.; Schweinzer, J.; Angioni, C.; Burckhart, A.; Challis, C. D.; Chapman, I.; Fischer, R.; Flanagan, J.; Frassinetti, L.; Giroud, C.; Hobirk, J.; Joffrin, E.; Kallenbach, A.; Kempenaars, M.; Leyland, M.; Lomas, P.; Maddison, G.; Maslov, M.; McDermott, R.; Neu, R.; Nunes, I.; Osborne, T.; Ryter, F.; Saarelma, S.; Schneider, P. A.; Snyder, P.; Tardini, G.; Viezzer, E.; Wolfrum, E.; the ASDEX Upgrade Team; Contributors, JET-EFDA

    2013-12-01

    In both JET and ASDEX Upgrade (AUG) the plasma energy confinement has been affected by the presence of a metal wall by the requirement of increased gas fuelling to avoid tungsten pollution of the plasma. In JET with a beryllium/tungsten wall the high triangularity baseline H-mode scenario (i.e. similar to the ITER reference scenario) has been the strongest affected and the benefit of high shaping to give good normalized confinement of H98 ˜ 1 at high Greenwald density fraction of fGW ˜ 0.8 has not been recovered to date. In AUG with a full tungsten wall, a good normalized confinement H98 ˜ 1 could be achieved in the high triangularity baseline plasmas, albeit at elevated normalized pressure βN > 2. The confinement lost with respect to the carbon devices can be largely recovered by the seeding of nitrogen in both JET and AUG. This suggests that the absence of carbon in JET and AUG with a metal wall may have affected the achievable confinement. Three mechanisms have been tested that could explain the effect of carbon or nitrogen (and the absence thereof) on the plasma confinement. First it has been seen in experiments and by means of nonlinear gyrokinetic simulations (with the GENE code), that nitrogen seeding does not significantly change the core temperature profile peaking and does not affect the critical ion temperature gradient. Secondly, the dilution of the edge ion density by the injection of nitrogen is not sufficient to explain the plasma temperature and pressure rise. For this latter mechanism to explain the confinement improvement with nitrogen seeding, strongly hollow Zeff profiles would be required which is not supported by experimental observations. The confinement improvement with nitrogen seeding cannot be explained with these two mechanisms. Thirdly, detailed pedestal structure analysis in JET high triangularity baseline plasmas have shown that the fuelling of either deuterium or nitrogen widens the pressure pedestal. However, in JET-ILW this

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Effect of compressibility on the hypervelocity penetration

    NASA Astrophysics Data System (ADS)

    Song, W. J.; Chen, X. W.; Chen, P.

    2017-06-01

    We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity penetration. Meanwhile, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.

  3. 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.

  4. 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.

  5. Intact capture of hypervelocity projectiles

    NASA Technical Reports Server (NTRS)

    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.

  6. Intact capture of hypervelocity projectiles

    NASA Technical Reports Server (NTRS)

    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.

  7. 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.

  8. Turbulent spots in hypervelocity flow

    NASA Astrophysics Data System (ADS)

    Jewell, Joseph S.; Leyva, Ivett A.; Shepherd, Joseph E.

    2017-04-01

    The turbulent spot propagation process in boundary layer flows of air, nitrogen, carbon dioxide, and air/carbon dioxide mixtures in thermochemical nonequilibrium at high enthalpy is investigated. Experiments are performed in a hypervelocity reflected shock tunnel with a 5-degree half-angle axisymmetric cone instrumented with flush-mounted fast-response coaxial thermocouples. Time-resolved and spatially demarcated heat transfer traces are used to track the propagation of turbulent bursts within the mean flow, and convection rates at approximately 91, 74, and 63% of the boundary layer edge velocity, respectively, are observed for the leading edge, peak, and trailing edge of the spots. A simple model constructed with these spot propagation parameters is used to infer spot generation rates from observed transition onset to completion distance. Spot generation rates in air and nitrogen are estimated to be approximately twice the spot generation rates in air/carbon dioxide mixtures.

  9. Hypervelocity impact on shielded plates

    NASA Technical Reports Server (NTRS)

    Smith, James P.

    1993-01-01

    A ballistic limit equation for hypervelocity impact on thin plates is derived analytically. This equation applies to cases of impulsive impact on a plate that is protected by a multi-shock shield, and it is valid in the range of velocity above 6 km/s. Experimental tests were conducted at the NASA Johnson Space Center on square aluminum plates. Comparing the center deflections of these plates with the theoretical deflections of a rigid-plastic plate subjected to a blast load, one determines the dynamic yield strength of the plate material. The analysis is based on a theory for the expansion of the fragmented projectile and on a simple failure criterion. Curves are presented for the critical projectile radius versus the projectile velocity, and for the critical plate thickness versus the velocity. These curves are in good agreement with curves that have been generated empirically.

  10. Experimental and Monte Carlo simulated spectra of a liquid-metal-jet x-ray source.

    PubMed

    Marziani, M; Gambaccini, M; Di Domenico, G; Taibi, A; Cardarelli, P

    2014-09-01

    A prototype x-ray system based on a liquid-metal-jet anode was evaluated within the framework of the LABSYNC project. The generated spectrum was measured using a CZT-based spectrometer and was compared with spectra simulated by three Monte Carlo codes: MCNPX, PENELOPE and EGS5. Notable differences in the simulated spectra were found. These are mainly attributable to differences in the models adopted for the electron-impact ionization cross section. The simulation that more closely reproduces the experimentally measured spectrum was provided by PENELOPE. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. 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.

  12. 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.

  13. Hypervelocity stars from young stellar clusters in the Galactic Centre

    NASA Astrophysics Data System (ADS)

    Fragione, G.; Capuzzo-Dolcetta, R.; Kroupa, P.

    2017-05-01

    The enormous velocities of the so-called hypervelocity stars (HVSs) derive, likely, from close interactions with massive black holes, binary stars encounters or supernova explosions. In this paper, we investigate the origin of HVSs as consequence of the close interaction between the Milky Way central massive black hole and a passing-by young stellar cluster. We found that both single and binary HVSs may be generated in a burst-like event, as the cluster passes near the orbital pericentre. High-velocity stars will move close to the initial cluster orbital plane and in the direction of the cluster orbital motion at the pericentre. The binary fraction of these HVS jets depends on the primordial binary fraction in the young cluster. The level of initial mass segregation determines the value of the average mass of the ejected stars. Some binary stars will merge, continuing their travel across and out of the Galaxy as blue stragglers.

  14. DIRECT EVIDENCE FOR OUTFLOW OF METAL-ENRICHED GAS ALONG THE RADIO JETS OF HYDRA A

    SciTech Connect

    Kirkpatrick, C. C.; Cavagnolo, K. W.; McNamara, B. R.; Gitti, M.; David, L. P.; Nulsen, P. E. J.; Wise, M. W.

    2009-12-10

    Using deep Chandra observations of the Hydra A galaxy cluster, we examine the metallicity structure near the central galaxy and along its powerful radio source. We show that the metallicity of the intracluster medium is enhanced by up to 0.2 dex along the radio jets and lobes compared to the metallicity of the undisturbed gas. The enhancements extend from a radius of 20 kpc from the central galaxy to a distance of approx120 kpc. We estimate the total iron mass that has been transported out of the central galaxy to be between 2 x 10{sup 7} M {sub sun} and 7 x 10{sup 7} M {sub sun}, which represents 10%-30% of the iron mass within the central galaxy. The energy required to lift this gas is roughly 1% to 5% of the total energetic output of the active galactic nuclei. Evidently, Hydra A's powerful radio source is able to redistribute metal-enriched, low entropy gas throughout the core of the galaxy cluster. The short re-enrichment timescale <10{sup 9} yr implies that the metals lost from the central galaxy will be quickly replenished.

  15. 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

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

    PubMed

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

    2015-11-25

    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.

  17. 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.

  18. 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.

  19. 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.

  20. Effects of Surface Roughness on Stagnation Heat Transfer of Impinging Liquid Jet on Metal Surface

    NASA Astrophysics Data System (ADS)

    Lee, Jungho

    The liquid jet impingement with phase change heat transfer has long been an attractive method of cooling especially in steelmaking process and heat treatment in metals. The current study focuses on making detailed measurements of the stagnation-point heat transfer as a jet impinges on the rough metal surfaces at high temperature nominally up to 900°C. The local heat flux measurements are introduced by a novel experimental technique in which test block assemblies with cartridge heaters and thermocouples are used to measure the heat flux distribution on the surface of hot steel plate as a function of heat flux gauge. The effects of surface roughness on the stagnation-point heat transfer were investigated for well-characterized four rough surfaces with root-mean-square average roughness heights ranging from 40 to 80 µm. The results show that surface protrusions on rough surface can penetrate the thermal sublayer in the stagnation point and thus increase the heat transfer. The heat transfer enhancement mechanism on roughened surface can be investigated by the different boiling regimes.

  1. Simulation of Motion, Heating, and Breakup of Molten Metal Droplets in the Plasma Jet at Plasma-Arc Spraying

    NASA Astrophysics Data System (ADS)

    Kharlamov, M. Yu.; Krivtsun, I. V.; Korzhyk, V. N.; Ryabovolyk, Y. V.; Demyanov, O. I.

    2015-04-01

    The mathematical model for the process of plasma-arc wire spraying is proposed, which describes behavior of molten metal droplets in the plasma jet, allowing for the processes of their deformation and gas-dynamic breakup. Numerical analysis of the processes of motion, heating, and breakup of molten metal droplets, detached from the sprayed wire at plasma-arc spraying of coatings, was performed. It is shown that during molten droplets movement in the plasma jet their multiple breakup takes place, leading to formation of sprayed particles with dimensions much smaller than dimensions of initial droplets, detached from the sprayed wire tip.

  2. 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.

  3. Hypervelocity impact damage in alumina

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng

    2007-12-01

    Ceramics are important engineering materials for their outstanding hardness. One of the most widely used ceramics is alumina, a candidate for armor in defense and aerospace industry. Deformation and fracture mechanisms in alpha-alumina under hypervelocity impact up to 18km/s are investigated using molecular dynamics (MD) simulations containing 540-million atoms. Impacting projectile causes melting and local amorphization of the substrate in a spherical surrounding region. Away from the impact face, a wide range of deformations emerge and disappear under the influence of local stress fields, e.g., basal and pyramidal slips, basal and rhombohedral twins, which show good agreement with the experimental and theoretical results. Furthermore, new deformation modes such as twin along {01¯11} are observed, and the relation between deformation patterns and local stress levels are probed. During unloading, micro-cracks nucleate extensively at the intersections of previous deformations. These micro-cracks grow and coalesce to form fractures under tensile stresses by the unloading wave. The substrate eventually fails along the surface of an hourglass-shaped region, when spallation ejects clusters of substrate material into the vacuum. We also carried out planar shock simulations of alpha-alumina single crystal and nanophase systems. The results show correlations between the atomistic deformation mechanisms and the elastic-plastic response of ceramic material observed in shock loading experiments.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Use of shutdown of the capacitive storage in implementing electrical action on metallic shaped-charge jets

    NASA Astrophysics Data System (ADS)

    Fedorov, S. V.

    2016-03-01

    Tto improve the efficiency of electrical action on metallic shaped-charge jets, it is proposed to use shutdown of the capacitive storage at the time when the voltage on it during passage of an alternating discharge becomes zero. It has been shown that using this expedient eliminates recharging of the capacitive storage and provides better matching between the current pulse and the time of motion of various parts of the shaped-charge jet through the electrode gap. Studies have been conducted using a computational procedure in which the development of magnetohydrodynamic instability of the jet and the dispersion of its material are considered possible physical mechanisms reducing the penetration capability of shaped-charge jets under the action of high current pulses.

  9. Highly conductive metal interconnects on three-dimensional objects fabricated with omnidirectional ink jet printing technology

    NASA Astrophysics Data System (ADS)

    Yoshida, Yasunori; Wada, Hikaru; Izumi, Konami; Tokito, Shizuo

    2017-05-01

    In this work, we demonstrate that highly conductive metal interconnects can be fabricated on the surface of three-dimensional objects using “omnidirectional ink jet” (OIJ) printing technology. OIJ printing technology makes it possible to perform ink jet printing in all directions by combining the motion of a 6-axis vertically articulated robot with precise positioning and a thermal drying process, which allows for the printing of stacked layers. By using OIJ technology, we were the first to successfully fabricate printed interconnect layers having a very low electrical resistance of 12 mΩ over a 10 mm length. Moreover, the results of the high-current test demonstrated that the printed interconnects can withstand high-current-flow of 5 A for 30 min or more.

  10. Etching of semiconductors and metals by the photonic jet with shaped optical fiber tips

    NASA Astrophysics Data System (ADS)

    Pierron, Robin; Lecler, Sylvain; Zelgowski, Julien; Pfeiffer, Pierre; Mermet, Frédéric; Fontaine, Joël

    2017-10-01

    The etching of semiconductors and metals by a photonic jet (PJ) generated with a shaped optical fiber tip is studied. Etched marks with a diameter of 1 μm have been realized on silicon, stainless steel and titanium with a 35 kHz pulsed laser, emitting 100 ns pulses at 1064 nm. The selection criteria of the fiber and its tip are discussed. We show that a 100/140 silica fiber is a good compromise which takes into account the injection, the working distance and the energy coupled in the higher-order modes. The energy balance is performed on the basis of the known ablation threshold of the material. Finally, the dependence between the etching depth and the number of pulses is studied. Saturation is observed probably due to a redeposition of the etched material, showing that a higher pulse energy is required for deeper etchings.

  11. Erosive wear of ductile metals by a particle-laden high velocity liquid jet

    SciTech Connect

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

    1981-11-30

    In this paper, 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 Al2O3 and SiC suspensions in water. Slurry velocities of up to 130 ft s-1 (40 m s-1) and impingement angles of 15°–90° were investigated. The maximum particle concentration used was 40 wt.%. For high velocity the results of this work show two erosion maxima; these are found at impingement angles of 90° and 40°. However, in corresponding gas-solid particle investigations maximum erosion occurs at approximately 20°. In this work both particle concentration and composition were varied. Finally, a polynomial regression technique was used to calculate empirical and semitheoretical correlation constants.

  12. 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

  13. 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

  14. 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.

  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 observations of the breakup of multiple metal jets in a volatile liquid

    SciTech Connect

    Marciniak, Michael James

    1995-01-01

    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; "pre-mixing" 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.

  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. 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.

  19. The NASA JSC Hypervelocity Impact Test Facility (HIT-F)

    NASA Technical Reports Server (NTRS)

    Crews, Jeanne L.; Christiansen, Eric L.

    1992-01-01

    The NASA Johnson Space Center Hypervelocity Impact Test Facility was created in 1980 to study the hypervelocity impact characteristics of composite materials. The facility consists of the Hypervelocity Impact Laboratory (HIRL) and the Hypervelocity Analysis Laboratory (HAL). The HIRL supports three different-size light-gas gun ranges which provide the capability of launching particle sizes from 100 micron spheres to 12.7 mm cylinders. The HAL performs three functions: (1) the analysis of data collected from shots in the HIRL, (2) numerical and analytical modeling to predict impact response beyond test conditions, and (3) risk and damage assessments for spacecraft exposed to the meteoroid and orbital debris environments.

  20. Global and pedestal confinement in JET with a Be/W metallic wall

    NASA Astrophysics Data System (ADS)

    Beurskens, M. N. A.; Frassinetti, L.; Challis, C.; Giroud, C.; Saarelma, S.; Alper, B.; Angioni, C.; Bilkova, P.; Bourdelle, C.; Brezinsek, S.; Buratti, P.; Calabro, G.; Eich, T.; Flanagan, J.; Giovannozzi, E.; Groth, M.; Hobirk, J.; Joffrin, E.; Leyland, M. J.; Lomas, P.; de la Luna, E.; Kempenaars, M.; Maddison, G.; Maggi, C.; Mantica, P.; Maslov, M.; Matthews, G.; Mayoral, M.-L.; Neu, R.; Nunes, I.; Osborne, T.; Rimini, F.; Scannell, R.; Solano, E. R.; Snyder, P. B.; Voitsekhovitch, I.; de Vries, Peter; Contributors, JET-EFDA

    2014-04-01

    Type I ELMy H-mode operation in JET with the ITER-like Be/W wall (JET-ILW) generally occurs at lower pedestal pressures compared to those with the full carbon wall (JET-C). The pedestal density is similar but the pedestal temperature where type I ELMs occur is reduced and below to the so-called critical type I-type III transition temperature reported in JET-C experiments. Furthermore, the confinement factor H98(y,2) in type I ELMy H-mode baseline plasmas is generally lower in JET-ILW compared to JET-C at low power fractions Ploss/Pthr,08 < 2 (where Ploss is (Pin - dW/dt), and Pthr,08 the L-H power threshold from Martin et al 2008 (J. Phys. Conf. Ser. 123 012033)). Higher power fractions have thus far not been achieved in the baseline plasmas. At Ploss/Pthr,08 > 2, the confinement in JET-ILW hybrid plasmas is similar to that in JET-C. A reduction in pedestal pressure is the main reason for the reduced confinement in JET-ILW baseline ELMy H-mode plasmas where typically H98(y,2) = 0.8 is obtained, compared to H98(y,2) = 1.0 in JET-C. In JET-ILW hybrid plasmas a similarly reduced pedestal pressure is compensated by an increased peaking of the core pressure profile resulting in H98(y,2) ⩽ 1.25. The pedestal stability has significantly changed in high triangularity baseline plasmas where the confinement loss is also most apparent. Applying the same stability analysis for JET-C and JET-ILW, the measured pedestal in JET-ILW is stable with respect to the calculated peeling-ballooning stability limit and the ELM collapse time has increased to 2 ms from typically 200 µs in JET-C. This indicates that changes in the pedestal stability may have contributed to the reduced pedestal confinement in JET-ILW plasmas. A comparison of EPED1 pedestal pressure prediction with JET-ILW experimental data in over 500 JET-C and JET-ILW baseline and hybrid plasmas shows a good agreement with 0.8 < (measured pped)/(predicted pped,EPED) < 1.2, but that the role of triangularity is generally

  1. 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

  2. Stand-off shields for hypervelocity particles

    SciTech Connect

    Lawrence, R.J.

    1989-01-01

    Stand-off hypervelocity particle shields offer potential weight savings of an order of magnitude or more over conventional homogeneous armors. Based on an earlier complete model for the design and optimization of a stand-of shield system, a more restricted model appropriate for retrofit shields is described. Procedures to minimize the shield mass are provided, and scaling laws for many of the important parameter relationships are illustrated. 6 refs., 5 figs.

  3. Hypervelocity, minimum-radii, coordinated turns

    NASA Technical Reports Server (NTRS)

    Tauber, Michael E.

    1990-01-01

    An analytic solution is presented for the most basic powered-flight maneuver, consisting of a constant-altitude coordinated turn and expressions for minimum-turn radii; associated flight conditions are derived. It is shown that the formulation for hypervelocity turns differs from that for subsonic and hypersonic speeds. Illustrative calculations using approximate aerodynamics based on Newtonian theory are presented, and these demonstrate the differences of hypersonic flight conditions and their associated turning radii from those at lower speeds.

  4. 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.

  5. 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.

  6. Beryllium coatings on metals for marker tiles at JET: development of process and characterization of layers

    NASA Astrophysics Data System (ADS)

    Lungu, C. P.; Mustata, I.; Zaroschi, V.; Lungu, A. M.; Anghel, A.; Chiru, P.; Rubel, M.; Coad, P.; Matthews, G. F.

    2007-03-01

    Preparatory study for the operation of the JET tokamak with a full metal wall (ITER-like wall project) also comprises several activities aiming at the development of thin beryllium coatings. The purpose is 2-fold: (i) to coat Inconel® tiles of the inner wall cladding; (ii) to develop methods for production of films for so-called marker tiles in order to enable monitoring of Be erosion from limiters. Properties of the marker film must match, as closely as possible, those of bulk Be. The first step in the R&D process was to assess coating methods and the quality of layers deposited on test coupons. Smooth, dense Be films of high purity and good adhesion to the substrate were deposited with an average deposition rate of 5±0.5 nm s-1 to a thickness of 7.5 μm. A marker structure consisting of a 7.5 μm Be film on top of a 2.5 μm Ni interlayer deposited on a bulk Be block has been developed and characterized by means of material analysis methods. An overview of manufacturing processes and properties of the marker coatings is presented.

  7. Liquefied metal jet program Automation and Robotics Research Institute (ARRI). Final technical report

    SciTech Connect

    Terrill, R.E.; Dringenburg, N.; Smith, C.; DuBois, P.; Priest, J.

    1995-12-15

    Department of Defense (DoD) agencies are major users of electronics and are responsible for much of the current printing wiring board (PWB) manufacturing. Current manufacturing of PWBs utilizes photolithography and chemical etchings which are subtractive processing techniques creating tons of hazardous waste materials and waste water each year. The current processing techniques apply photoresist to the surface of a copper clad board only to remove more than 90 percent of both copper and resist in the next phase of processing. The subtractive process is, by design, a wasteful processing technique. Current manufacturing processes limit the line size and spaces which determine the circuit density and number of PWB layers. The proposed alternative manufacturing technology is Liquid Metal Jetting (LMJ). While offering significant reductions in hazardous waste produced and reduced overall processing cost, LMJ can also excel in one-of-a-kind and replication type PWB board production. The proposed process can produce extremely fine PWB patterns with circuit lines much smaller than existing technologies. With a direct Computer Aided Design (CAD) interface, the LMJ process is especially compatible with one-of-a-kind and rapid prototyping applications.

  8. Laboratory investigations of the survivability of bacteria in hypervelocity impacts.

    PubMed

    Burchell, M J; Shrine, N R; Mann, J; Bunch, A W; Brandao, P; Zarnecki, J C; Galloway, J A

    2001-01-01

    It is now well established that material naturally moves around the Solar System, even from planetary surface to planetary surface. Accordingly, the idea that life is distributed throughout space and did not necessarily originate on the Earth but migrated here from elsewhere (Panspermia) is increasingly deemed worthy of consideration. If life arrived at the Earth from space, its relative speed will typically be of order many km s-1, and the resulting collision with the Earth and its atmosphere will be in the hypervelocity regime. A mechanism for the bacteria to survive such an impact is required. Therefore a programme of hypervelocity impacts in the laboratory at (4.5 +/- 0.6) km s-1 was carried out using bacteria (Rhodococcus) laden projectiles. After impacts on a variety of target materials (rock, glass and metal) attempts were made to culture Rhodococcus from the surface of the resulting craters and also from the target material ejected during crater formation. Control shots with clean projectiles yielded no evidence for Rhodococcus growth from any crater surface or ejecta. When projectiles doped with Rhodococcus were used no impact crater surface yielded colonies of Rhodococcus. However, for four shots of bacteria into rock (two on chalk and two on granite) the ejecta was afterwards found to give colonies of Rhodococcus. This was not true for shots onto glass. In addition, shots into aerogel (density 96 kg m-3) were also carried out (two with clean projectiles and two with projectiles with Rhodococcus). This crudely simulated aero-capture in a planetary atmosphere. No evidence for Rhodococcus growth was found from the projectiles captured in the aerogel from any of the four shots.

  9. 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

  10. Analysis of Computational Models of Shaped Charges for Jet Formation and Penetration

    NASA Astrophysics Data System (ADS)

    Haefner, Jonah; Ferguson, Jim

    2016-11-01

    Shaped charges came into use during the Second World War demonstrating the immense penetration power of explosively formed projectiles and since has become a tool used by nearly every nation in the world. Penetration is critically dependent on how the metal liner is collapsed into a jet. The theory of jet formation has been studied in depth since the late 1940s, based on simple models that neglect the strength and compressibility of the metal liner. Although attempts have been made to improve these models, simplifying assumptions limit the understanding of how the material properties affect the jet formation. With a wide range of material and strength models available for simulation, a validation study was necessary to guide code users in choosing models for shaped charge simulations. Using PAGOSA, a finite-volume Eulerian hydrocode designed to model hypervelocity materials and strong shock waves developed by Los Alamos National Laboratory, and experimental data, we investigated the effects of various equations of state and material strength models on jet formation and penetration of a steel target. Comparing PAGOSA simulations against modern experimental data, we analyzed the strengths and weaknesses of available computational models. LA-UR-16-25639 Los Alamos National Laboratory.

  11. 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.

  12. 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.

  13. Hypervelocity Plasmas with Strong MHD (Magnetohydrodynamic) Interactions.

    DTIC Science & Technology

    1984-12-01

    ARD-Ai5S 867 HYPERVELOCITY PLASMAS WITH STRONG NHD j/j (MAGNETOHYDRODYNANIC) INTERRCTIONS(U) STD RESEARCH CORP ARCADIA CA S T DEMETRIADES FT AL DEC...MIRCP RSLTO-TS HR NAINLBUEUO SADRS-16- -ArO’ mi -T7- (7 % STD RESEARCH CORPORATION POST OFFICE OX ’C’ ARC ADIA, CALIFORNIA 91006 LTf.LEPHONE! (213...Covered: 1 June 1983 -31 May 1984 December 1984 STD Research Corporation P.O. Box "’C" Arcadia, California 91006 Appi-u ’, 2 I~t or1 ’Pub I rege

  14. 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.

  15. 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.

  16. 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.

  17. Hypervelocity Railgun:. the Optimal Solutions

    NASA Astrophysics Data System (ADS)

    Ostashev, V. E.; Lebedev, E. F.; Fortov, V. E.

    2004-11-01

    The paper describes the concept of a multistage plasma armature railgun (PARG). A conventional multistage PARG can be disabled to operate principally as an electromagnetic (EM) launcher. In order to create a multistage PARG one must create acceleration in each rail gun (RG) section, initiating the PA from a new metal foil adjacent to the back of the projectile; to ignite discharge moving with projectile velocity, to stabilize the PA at the initial phase of acceleration in each section while d(mv)<0 to decrease the duration of this phase at the expense of a quickly growing RG current; to form specific time dependence of the energy supply for each RG section both for igniting the discharge, and accelerating the plasma without changing energy sources; and to alternatively feed the energy supply. Presented is the computer evaluation of the acceleration of a 2 g projectile from its initial velocity of 5km/s over an acceleration distance of 2.5m, with a permissible operating current of up to 1 MA. The proposed pulse-forming network (PFN) creates a powerful impulse for initiating PA from a metal foil, and also forms a quickly growing RG current. This PFN can transfer up to 45% of its initial energy into RG. The calculated results have shown that, under these circumstances, a muzzle velocity of 10-12 km/s may be achieved in PARG.

  18. Transient cooling of a hot metal plate with an impinging water jet

    SciTech Connect

    Kumagai, Satoshi; Suzuki, Shinju; Kubo, Ryo; Kawazoe, Masataka

    1995-12-31

    Transient boiling heat-transfer rate of a two-dimensional impinging water jet was measured throughout the surface of a 20 x 150 mm rectangle, during cooling from approximately 400 C to 100 C. Time-dependent surface-temperature distributions and the progress of a solid-liquid contact front were obtained for jet subcooling from 14 K to 50 K. Solid-liquid contact at the stagnation line starts from the moment of jet impingement, where violent boiling occurs and generated vapor splashes the water film; this results in deprivation of water supply to the outer region of the surface. The temperature of the outer surface remains high up to the time when the solid-liquid contact front reaches it and a large temperature gradient appears near the front. The surface temperature for the initiation of solid-liquid contact is higher at locations nearer the stagnation line and with higher jet subcooling.

  19. Hypervelocity runaways from the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Boubert, D.; Erkal, D.; Evans, N. W.; Izzard, R. G.

    2017-08-01

    We explore the possibility that the observed population of Galactic hypervelocity stars (HVSs) originate as runaway stars from the Large Magellanic Cloud (LMC). Pairing a binary evolution code with an N-body simulation of the interaction of the LMC with the Milky Way, we predict the spatial distribution and kinematics of an LMC runaway population. We find that runaway stars from the LMC can contribute Galactic HVSs at a rate of 3 × 10-6 yr-1. This is composed of stars at different points of stellar evolution, ranging from the main sequence to those at the tip of the asymptotic giant branch. We find that the known B-type HVSs have kinematics that are consistent with an LMC origin. There is an additional population of hypervelocity white dwarfs whose progenitors were massive runaway stars. Runaways that are even more massive will themselves go supernova, producing a remnant whose velocity will be modulated by a supernova kick. This latter scenario has some exotic consequences, such as pulsars and supernovae far from star-forming regions, and a small rate of microlensing from compact sources around the halo of the LMC.

  20. 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.

  1. Transit probabilities around hypervelocity and runaway stars

    NASA Astrophysics Data System (ADS)

    Fragione, G.; Ginsburg, I.

    2017-04-01

    In the blooming field of exoplanetary science, NASA's Kepler Space Telescope has revolutionized our understanding of exoplanets. Kepler's very precise and long-duration photometry is ideal for detecting planetary transits around Sun-like stars. The forthcoming Transiting Exoplanet Survey Satellite (TESS) is expected to continue Kepler's legacy. Along with transits, the Doppler technique remains an invaluable tool for discovering planets. The next generation of spectrographs, such as G-CLEF, promise precision radial velocity measurements. In this paper, we explore the possibility of detecting planets around hypervelocity and runaway stars, which should host a very compact system as consequence of their turbulent origin. We find that the probability of a multiplanetary transit is 10-3 ≲ P ≲ 10-1. We therefore need to observe ∼10-1000 high-velocity stars to spot a transit. However, even if transits are rare around runaway and hypervelocity stars, the chances of detecting such planets using radial velocity surveys is high. We predict that the European Gaia satellite, along with TESS and the new-generation spectrographs G-CLEF and ESPRESSO, will spot planetary systems orbiting high-velocity stars.

  2. Invisible metal-grid transparent electrode prepared by electrohydrodynamic (EHD) jet printing

    NASA Astrophysics Data System (ADS)

    Jang, Yonghee; Kim, Jihoon; Byun, Doyoung

    2013-04-01

    Invisible Ag-grid transparent electrodes (TEs) were prepared by electrohydrodynamic (EHD) jet printing using Ag nano-particle inks. Ag-grid width less than 10 µm was achieved by the EHD jet printing, which was invisible to the naked eye. The Ag-grid line-to-line distance (pitch) was modulated in order to investigate the electrical and optical properties of the EHD jet-printed Ag-grid TEs. The decrease in the sheet resistance at the expense of the transmittance was observed as the Ag-grid pitch decreased. The figure of merit of Ag-grid TEs with various Ag-grid pitches was investigated in order to determine the optimum pitch condition for both electrical and optical properties. With the 150 µm Ag-grid pitch, the EHD jet-printed Ag-grid TE has the sheet resistance of 4.87 Ω sq-1 and the transmittance of 81.75% after annealing at 200 °C under near-infrared. Ag filling factor (FF) was defined to predict the electrical and optical properties of Ag-grid TEs. It was found that the measured electrical and optical properties were well simulated by the theoretical equations incorporating FF. The EHD jet-printed invisible Ag-grid TE with good electrical and optical properties implies its promising application to the printed optoelectronic devices.

  3. 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.

  4. 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.

  5. 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.

  6. NASA White Sands Test Facility Remote Hypervelocity Test Laboratory

    NASA Image and Video Library

    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/...

  7. 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.

  8. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Dynamics of formation of the liquid-drop phase of laser erosion jets near the surfaces of metal targets

    NASA Astrophysics Data System (ADS)

    Goncharov, V. K.; Kontsevoi, V. L.; Puzyrev, M. V.

    1995-03-01

    An investigation was made of laser erosion jets formed at 0.1-1.5 mm above the surfaces of Pb, Co, Ni, Sn, and Zn targets. A neodymium laser emitting rectangular pulses of 400 μs duration and of energy up to 400 J was used. The diameters, as well as the number density and volume fraction of the metal particles present in the jet, were measured. An analysis of the results showed that the metal liquid drops broke up near the surface and experienced additional evaporation because of their motion opposite to the laser beam.

  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. An approximate Riemann solver for hypervelocity flows

    NASA Technical Reports Server (NTRS)

    Jacobs, Peter A.

    1991-01-01

    We describe an approximate Riemann solver for the computation of hypervelocity flows in which there are strong shocks and viscous interactions. The scheme has three stages, the first of which computes the intermediate states assuming isentropic waves. A second stage, based on the strong shock relations, may then be invoked if the pressure jump across either wave is large. The third stage interpolates the interface state from the two initial states and the intermediate states. The solver is used as part of a finite-volume code and is demonstrated on two test cases. The first is a high Mach number flow over a sphere while the second is a flow over a slender cone with an adiabatic boundary layer. In both cases the solver performs well.

  11. Molecular Dynamics Simulations of Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Owens, Eli T.; Bachlechner, Martina E.

    2007-03-01

    Outer space silicon solar cells are exposed to impacts with micro meteors that can destroy the surface leading to device failure. A protective coating of silicon nitride will protect against such failure. Large-scale molecular dynamics simulations are used to study how silicon/silicon nitride fails due to hypervelocity impacts. Three impactors made of silicon nitride are studied. Their cross-sectional areas, relative to the target, are as follows: the same as the target, half of the target, and a quarter of the target. Impactor speeds from 5 to 11 km/second yield several modes of failure, such as deformation of the target by the impactor and delimitation of the silicon nitride from the silicon at the interface. These simulations will give a much clearer picture of how solar cells composed of a silicon/silicon nitride interface will respond to impacts in outer space. This will ultimately lead to improved devices with longer life spans.

  12. A test facility for hypervelocity rarefied flows

    NASA Astrophysics Data System (ADS)

    Macrossan, M. N.; Chiu, H.-H.; Mee, D. J.

    2001-08-01

    This paper describes a rarefied hypervelocity test facility producing gas speeds greater than 7 km/s. The X1 expansion tube at The University of Queensland has been used to produce nitrogen flows at 8.9 and 9.5 km/s with test flow durations of 50 and 40 μs respectively. Rarefied flow is indicated by values of the freestream breakdown parameter >0.1 (Cheng's rarefaction parameter <10) and freestream Knudsen numbers up to 0.038, based on a model size of 9 mm. To achieve this, the test gas is expanded from the end of the acceleration tube into a dump tank. Nominal conditions in the expansion are derived from CFD predictions. Measured bar gauge (Pitot) pressures show that the flow is radially uniform when the Pitot pressure has decreased by a factor ten. The measured bar gauge pressures are an increasing fraction of the expected Pitot pressure as the rarefaction parameters increase.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. A novel three-jet microreactor for localized metal-organic chemical vapour deposition of gallium arsenide: design and simulation

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2016-08-01

    We present a novel three-jet microreactor design for localized deposition of gallium arsenide (GaAs) by low-pressure Metal-Organic Chemical Vapour Deposition (MOCVD) for semiconductor devices, microelectronics and solar cells. Our approach is advantageous compared to the standard lithography and etching technology, since it preserves the nanostructure of the deposited material, it is less time-consuming and less expensive. We designed two versions of reactor geometry with a 10-micron central microchannel for precursor supply and with two side jets of a dilutant to control the deposition area. To aid future experiments, we performed computational modeling of a simplified-geometry (twodimensional axisymmetric) microreactor, based on Navier-Stokes equations for a laminar flow of chemically reacting gas mixture of Ga(CH3)3-AsH3-H2. Simulation results show that we can achieve a high-rate deposition (over 0.3 μm/min) on a small area (less than 30 μm diameter). This technology can be used in material production for microelectronics, optoelectronics, photovoltaics, solar cells, etc.

  3. Theoretical model for high-power diamond laser optics using high-velocity liquid-metal jet impingement cooling

    NASA Astrophysics Data System (ADS)

    Palmer, James R.

    1993-02-01

    In 1988 I presented a paper, `Fly's Eye Modular Optic,' in the Los Angeles Symposium that described an optic for high power laser systems that provided for a modular system of hexagonal components that were independently cooled using a high velocity jet pointed normal to the back surface of the optical faceplate. In this paper we look at the use of diamond optical materials in concert with high velocity jet impingement heat transfer of various liquid metal mediums. By using this combination of techniques and materials we can push the laser damage threshold of optical components to even higher levels of absorbed flux density. The thrust of this paper is to develop a theoretical model for use on optical elements subject to very high continuous flux density lasers and to evaluate the use of commercial diamond substrates with conventional optical thin films and conventional substrates with CVD diamond films. In order to assume the very high absorbed flux densities, it is necessary to have a heat transfer technique capable of maintaining the optical component at a stable temperature and below the damage threshold of the optical materials. For the more common materials, thermal shock and subsequent failure in bi-axial shear have proven to be one of the major constituents of the optical damage. In this paper we look at the thermal shock, vis-a-vis, the melting point of some of the materials.

  4. Theory and experiments characterizing hypervelocity impact plasmas on biased spacecraft materials

    SciTech Connect

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

    2013-03-15

    Space weather including solar activity and background plasma sets up spacecraft conditions that can magnify the threat from hypervelocity impacts. Hypervelocity impactors include both meteoroids, traveling between 11 and 72 km/s, and orbital debris, with typical impact speeds of 10 km/s. When an impactor encounters a spacecraft, its kinetic energy is converted over a very short timescale into energy of vaporization and ionization, resulting in a small, dense plasma. This plasma can produce radio frequency (RF) emission, causing electrical anomalies within the spacecraft. In order to study this phenomenon, we conducted ground-based experiments to study hypervelocity impact plasmas using a Van de Graaff dust accelerator. Iron projectiles ranging from 10{sup -16} g to 10{sup -11} g were fired at speeds of up to 70 km/s into a variety of target materials under a range of surface charging conditions representative of space weather effects. Impact plasmas associated with bare metal targets as well as spacecraft materials were studied. Plasma expansion models were developed to determine the composition and temperature of the impact plasma, shedding light on the plasma dynamics that can lead to spacecraft electrical anomalies. The dependence of these plasma properties on target material, impact speed, and surface charge was analyzed. Our work includes three major results. First, the initial temperature of the impact plasma is at least an order of magnitude lower than previously reported, providing conditions more favorable for sustained RF emission. Second, the composition of impact plasmas from glass targets, unlike that of impact plasmas from tungsten, has low dependence on impact speed, indicating a charge production mechanism that is significant down to orbital debris speeds. Finally, negative ion formation has a strong dependence on target material. These new results can inform the design and operation of spacecraft in order to mitigate future impact-related space

  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. 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.

  7. On the Origin of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Yu, Q.; Lu, Y.

    2011-05-01

    Hypervelocity stars (HVSs) moving in the Galactic halo are mainly B-type stars with origin of their progenitors unknown. OB stars are also populated in the Galactic Center (GC), with many being hosted in a clockwise rotating young stellar (CWS) disk within half a parsec from the central massive black hole (MBH) and their formation remaining puzzles. We find that the majority of the detected HVSs are spatially correlated with the plane of the stellar disk. By demonstrating that HVSs can well memorize the injecting direction of their progenitors, we conclude that most of the HVSs probably originate from the CWS disk. Our results not only confirm the GC origin of HVSs but also imply that the central disk 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. A future survey of HVSs in the southern hemisphere will provide a check for the origin of HVSs.

  8. 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.

  9. The True Origin of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Gnedin, Oleg

    2011-10-01

    We propose to obtain WFC3 images of 4 hypervelocity stars in the Galactic halo, in order to conclusively establish their origin. This will be a final epoch of a long-term program to measure precise proper motions in an absolute inertial frame. The origin of these unique stars with extremely large positive radial velocities, in excess of the escape speed from the Galaxy, is consistent only with being ejected by the massive black hole at the Galactic center. Reconstructing the full three-dimensional space motion of these stars, through astrometric proper motions, provides a unique opportunity to measure the shape of the triaxial dark matter halo, at larger distances than is afforded by tidal streams. In Cycles 15 and 17 our team obtained two epochs of observations for these stars with ACS. The accuracy of the proper motion measurement was affected by the CTE degradation in ACS and the unexpected change in the PSF after SM4. The CTE error of HVS3 was unfortunately amplified by the need to use different guide stars and take the second-epoch observations at a 180 degree different orientation. We request third-epoch observations for 4 targets with WFC3 to double the proper motion baseline to 5-6 years and to reduce the systematic error using our newly-developed CTE correction. The new measurement will conclusively confirm or reject the Galactocentric origin of HVSs.

  10. Searching for momentum enhancement in hypervelocity impacts

    SciTech Connect

    Stradling, G.L.; Idzorek, G.C.; Keaton, P.W.; Studebaker, J.K. ); Blossom, A.A.H. ); Collopy, M.T.; Curling, H.L. Jr. ); Bergeson, S.D. )

    1990-01-01

    In conjunction with the Los Alamos National Laboratory hypervelocity microparticle impact (HMI) team effort to produce higher impact velocities and to understand the physics of crater formation and momentum transfer, the authors have implemented a low noise microphone as a momentum detector on both the 6 MV Van de Graaff and 85 KV test stand' particle accelerators. Calculations are presented showing that the impulse response of a circular membrane. When used as a momentum impulse detector, the microphone theoretically may detect impulses as small as 8.8 {times} 10{sup {minus}15} N s. Sensitivity of the microphone in this application is limited by the noise threshold of the electronic amplifiers and the ambient microphinic vibration of the system. Calculations lead the authors to anticipate detection of particles over the full range of the Van de Graaff acceleration capability and up to 7 km/s on the test stand. They present momentum enhancement data in the velocity range between 10 km/s and 20 km/s. Preliminary work is presented on momentum impulse calibration of the microphone using laser-pulse photon momentum as an impulse source.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Jet drills. 57.7801 Section 57.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A...

  16. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Jet drills. 57.7801 Section 57.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A...

  17. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Jet drills. 56.7801 Section 56.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to...

  18. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Jet drills. 56.7801 Section 56.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to...

  19. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Jet drills. 57.7801 Section 57.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A...

  20. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Jet drills. 57.7801 Section 57.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A...

  1. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Jet drills. 56.7801 Section 56.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to...

  2. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Jet drills. 56.7801 Section 56.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to...

  3. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Jet drills. 56.7801 Section 56.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to...

  4. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Jet drills. 57.7801 Section 57.7801 Mineral... HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A...

  5. Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing.

    PubMed

    Ly, Sonny; Rubenchik, Alexander M; Khairallah, Saad A; Guss, Gabe; Matthews, Manyalibo J

    2017-06-22

    The results of detailed experiments and finite element modeling of metal micro-droplet motion associated with metal additive manufacturing (AM) processes are presented. Ultra high speed imaging of melt pool dynamics reveals that the dominant mechanism leading to micro-droplet ejection in a laser powder bed fusion AM is not from laser induced recoil pressure as is widely believed and found in laser welding processes, but rather from vapor driven entrainment of micro-particles by an ambient gas flow. The physics of droplet ejection under strong evaporative flow is described using simulations of the laser powder bed interactions to elucidate the experimental results. Hydrodynamic drag analysis is used to augment the single phase flow model and explain the entrainment phenomenon for 316 L stainless steel and Ti-6Al-4V powder layers. The relevance of vapor driven entrainment of metal micro-particles to similar fluid dynamic studies in other fields of science will be discussed.

  6. An investigation of contoured wall injectors for hypervelocity mixing augmentation

    NASA Astrophysics Data System (ADS)

    Waitz, Ian A.

    A parametric study of a class of contoured wall fuel injectors is presented. The injectors were aimed at enabling shock-enhanced mixing for the supersonic combustion ramjet engines currently envisioned for applications on hypersonic vehicles. Short combustor residence time, a requirement for fuel injection parallel to the freestream, and strong sensitivity of overall vehicle performance to combustion efficiency motivated the investigation. Several salient parametric dependencies were investigated. Injector performance was evaluated in terms of mixing, losses, jet penetration and heating considerations.A large portion of the research involved a series of tests conducted at the NASA Langley High - Reynolds Number Mach 6 Wind-Tunnel. Helium was used as an injectant gas to simulate hydrogen fuel. The parameters investigated include injector spacing, boundary layer height, and injectant to freestream pressure and velocity ratios. Conclusions concerning injector performance and parameter dependencies are supported by extensive three-dimensional flow field surveys as well as data from a variety of flow visualization techniques including Rayleigh scattering, Schlieren, spark-shadowgraph, and surface oil flow.As an adjunct to these experiments, a three-dimensional Navier-Stokes solver was used to conduct a parametric study which closely tracked the experimental effort. The results of these investigations strongly complemented the experimental work. Use of the code also allowed research beyond the fairly rigid bounds of the experimental test matrix. These studies included both basic investigations of shock-enhanced mixing on generic injectors, and applied efforts such as combining film-cooling with the contoured wall injectors.Location of an oblique shock at the base of the injection plane was found to be a loss-effective method for enhancing hypervelocity mixing through baroclinic generation of vorticity and subsequent convection and diffusion. Injector performance was

  7. 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.

  8. 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.

  9. The velocity distribution of hypervelocity stars

    SciTech Connect

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

    2014-11-10

    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{sup –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{sup –1} with equal probability, while none are observed beyond ∼700 km s{sup –1} and the current detections are more clustered at low velocities 300-400 km s{sup –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 {sub min} ∼ 10 R {sub ☉} in the separation distribution.

  10. 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

  11. 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.

  12. 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.

  13. Field Method for Detection of Metal Deactivator Additive in Jet Fuel

    DTIC Science & Technology

    2009-04-01

    5 2.2.2 Metal salt doping of stationary phase .................................................. 6 2.2.3 DSTO open column ...didn’t require the use of portable spectrophotometers, solvents or reagents. The method chosen was based on open column chromatography using a small... column of silica gel that was coated with a copper salt. The indicator for the presence of MDA is a colour change in the silica gel. The copper salt

  14. Metal vapor micro-jet controls material redistribution in laser powder bed fusion additive manufacturing

    DOE PAGES

    Ly, Sonny; Rubenchik, Alexander M.; Khairallah, Saad A.; ...

    2017-06-22

    The results of detailed experiments and finite element modeling of metal micro-droplet motion associated with metal additive manufacturing (AM) processes are presented. Ultra high speed imaging of melt pool dynamics reveals that the dominant mechanism leading to micro-droplet ejection in a laser powder bed fusion AM is not from laser induced recoil pressure as is widely believed and found in laser welding processes, but rather from vapor driven entrainment of micro-particles by an ambient gas flow. The physics of droplet ejection under strong evaporative flow is described using simulations of the laser powder bed interactions to elucidate the experimental results.more » Hydrodynamic drag analysis is used to augment the single phase flow model and explain the entrainment phenomenon for 316 L stainless steel and Ti-6Al-4V powder layers. The relevance of vapor driven entrainment of metal micro-particles to similar fluid dynamic studies in other fields of science will be discussed.« less

  15. 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.

  16. Enlarged View - Hypervelocity Impact - Lunar Surface Material - CA

    NASA Image and Video Library

    1970-01-06

    S70-20416 (December 1969) --- Enlarged view show hypervelocity impact on iron particles of lunar surface material returned to Earth by the crew of the Apollo 11 lunar landing mission. This photograph, enlarged to 270 times the actual size, was taken by Dr. G. J. Wasserberg, J. DeVaney and K. Evans at the California Institute of Technology.

  17. 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.

  18. Enlarged view of hypervelocity impact of lunar surface material

    NASA Image and Video Library

    1970-01-06

    S70-20417 (December 1969) --- Enlarged view shows hypervelocity impact of cosmic dust on broken glass particles, taken during the examination of Apollo 11 lunar material by Dr. G. J. Wasserberg, J. DeVaney and K. Evans at California Institute of Technology. The photograph is enlarged 4,850 times actual size.

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

    SciTech Connect

    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(NO{sub 3}){sub 2} and Cd(NO{sub 3}){sub 2}.4H{sub 2}O aqueous solutions, respectively. The plasma is generated by focusing a nanosecond Nd:YAG ({lambda}=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 {mu}s. 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{sup 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. The production of platinum-coated silicate nanoparticle aggregates for use in hypervelocity impact experiments

    NASA Astrophysics Data System (ADS)

    Hillier, Jon K.; Sestak, S.; Green, S. F.; Postberg, F.; Srama, R.; Trieloff, M.

    2009-12-01

    We present a method for producing metal-coated low-density (≲1600 kg m -3) aggregate silicate dust particles for use in hypervelocity impact (HVI) experiments. Particles fabricated using the method are shown to have charged and electrostatically accelerated in the Max Planck Institut für Kernphysik (MPI-K) 2 MV Van de Graaff accelerator, allowing the production of impact ionisation mass spectra of silicate particles (impacting at velocities ranging from <4 to >30 km s -1, corresponding to sizes of >1 to <0.1 μm) using the large area mass analyser (LAMA) instrument, designed for cosmic dust detection in space. Potential uses for the coated grains, such as in the calibration of aerogel targets similar to those used on the Stardust spacecraft, are also discussed.

  5. Design considerations for a passive magnetic induction signal generator for sensing hypervelocity projectile passage

    SciTech Connect

    Hawke, R.S.; Susoeff, A.R.; Greenwood, D.W.

    1995-01-01

    Measurement of projectile passage after hypervelocity launch is an important measurement and/or trigger needed for electromagnetic launcher development. One method is to use a magnetic induction technique which takes advantage of the fact that a metal object passing through a magnetic field can move the magnetic flux aside and thereby produce a voltage in a coil. This type of system can be designed to use permanent magnets and thereby be totally passive. In addition this passive system can be designed to be insensitive to the high electromagnetic fields generated during the operation of electrothermal guns and railguns. This diagnostic has been used to trigger other electrically sensitive data acquisition equipment including flash x-rays and to determine the velocity of the projectile. This report discusses the results of tests and a comparison of data with a simple model for calculating the expected signal output of such a device.

  6. 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.

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

    PubMed

    Larsson, Daniel H; Lundström, Ulf; Westermark, Ulrica K; Arsenian Henriksson, Marie; Burvall, Anna; Hertz, Hans M

    2013-02-01

    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. 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 ∼7 μm x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. High-resolution absorption imaging is demonstrated on mice with CT, showing 50 μm 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. 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.

  8. 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

  9. Metal Jet Initiation of Bare and Covered Explosives; Summary of the Mechanism, Empirical Model and Some Applications

    DTIC Science & Technology

    1981-10-01

    expanding radially . The jet does not directly produce detonation even though it produces a large shock pressure on impact with the Composition B at the...observations and proposed mechanism indicate that the jet tip continually penetrated the target explosive within the compresed zone behind the precursor

  10. Characterization of hypervelocity metal fragments for explosive initiation

    DOE PAGES

    Yeager, John D.; Bowden, Patrick R.; Guildenbecher, Daniel R.; ...

    2017-07-17

    The fragment impact response of two plastic-bonded explosive (PBX) formulations was studied using explosively driven aluminum fragments. A generic aluminum-capped detonator generated sub-mm aluminum particles moving at hypersonic velocities. The ability of these fragments to initiate reaction or otherwise damage two PBX materials was assessed using go/no-go experiments at standoff distances of up to 160 mm. Lower density PBX 9407 (RDX-based) was initiable at up to 115 mm, while higher density PBX 9501 (HMX-based) was only initiable at up to 6 mm. Several techniques were used to characterize the size, distribution, and velocity of the particles. Witness plate materials, includingmore » copper and polycarbonate, and backlit high speed video were used to characterize the distribution of particles, finding that the aluminum cap did not fragment homogeneously but rather with larger particles in a ring surrounding finer particles. Finally, precise digital holography experiments were conducted to measure the three-dimensional shape and size of the fastest-moving fragments, which ranged between 100 and 700 μm and traveled between 2.2 and 3.2 km/s. Crucially, these experiments showed variability in the fragmentation in terms of the number of fragments at the leading edge of the fragment field, indicating that both single and multiple shock impacts could be imparted to the target material. As a result, these types of data are critical for safety experiments and hydrocode simulations to quantify shock-to-detonation transition mechanisms and the associated risk-margins for these materials.« less

  11. Characterization of hypervelocity metal fragments for explosive initiation

    NASA Astrophysics Data System (ADS)

    Yeager, John D.; Bowden, Patrick R.; Guildenbecher, Daniel R.; Olles, Joseph D.

    2017-07-01

    The fragment impact response of two plastic-bonded explosive (PBX) formulations was studied using explosively driven aluminum fragments. A generic aluminum-capped detonator generated sub-mm aluminum particles moving at hypersonic velocities. The ability of these fragments to initiate reaction or otherwise damage two PBX materials was assessed using go/no-go experiments at standoff distances of up to 160 mm. Lower density PBX 9407 (RDX-based) was initiable at up to 115 mm, while higher density PBX 9501 (HMX-based) was only initiable at up to 6 mm. Several techniques were used to characterize the size, distribution, and velocity of the particles. Witness plate materials, including copper and polycarbonate, and backlit high speed video were used to characterize the distribution of particles, finding that the aluminum cap did not fragment homogeneously but rather with larger particles in a ring surrounding finer particles. Finally, precise digital holography experiments were conducted to measure the three-dimensional shape and size of the fastest-moving fragments, which ranged between 100 and 700 μm and traveled between 2.2 and 3.2 km/s. Crucially, these experiments showed variability in the fragmentation in terms of the number of fragments at the leading edge of the fragment field, indicating that both single and multiple shock impacts could be imparted to the target material. These types of data are critical for safety experiments and hydrocode simulations to quantify shock-to-detonation transition mechanisms and the associated risk-margins for these materials.

  12. 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.

  13. Flash characteristics of plasma induced by hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Long, Renrong; Zhang, Qingming; Xue, Yijiang; Ju, Yuanyuan

    2016-08-01

    Using a two-stage light gas gun, a series of hypervelocity impact experiments was conducted in which 6.4-mm-diameter spherical 2024-aluminum projectiles impact 23-mm-thick targets made of the same material at velocities of 5.0, 5.6, and 6.3 km/s. Both an optical pyrometer composed of six photomultiplier tubes and a spectrograph were used to measure the flash of the plasma during hypervelocity impact. Experimental results show that, at a projectile velocity of 6.3 km/s, the strong flash lasted about 10 μs and reached a temperature of 4300 K. Based on the known emission lines of AL I, spectral methods can provide the plasma electron temperature. An electron-temperature comparison between experiment and theoretical calculation indicates that single ionization and secondary ionization are the two main ionizing modes at velocities 5.0-6.3 km/s.

  14. 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.

  15. Non-silica aerogels as hypervelocity particle capture materials

    NASA Astrophysics Data System (ADS)

    Jones, Steven M.

    2010-01-01

    The Stardust sample return mission to the comet Wild 2 used silica aerogel as the principal cometary and interstellar particle capture and return medium. However, since both cometary dust and interstellar grains are composed largely of silica, using a silica collector complicates the science that can be accomplished with these particles. The use of non-silica aerogel in future extra-terrestrial particle capture and return missions would expand the scientific value of these missions. Alumina, titania, germania, zirconia, tin oxide, and resorcinol/formaldehyde aerogels were produced and impact tested with 20, 50, and 100μm glass microspheres to determine the suitability of different non-silica aerogels as hypervelocity particle capture mediums. It was found that non-silica aerogels do perform as efficient hypervelocity capture mediums, with alumina, zirconia, and resorcinol/formaldehyde aerogels proving to be the best of the materials tested.

  16. Reactive molecular dynamics of hypervelocity collisions of PETN molecules.

    PubMed

    Landerville, A C; Oleynik, I I; White, C T

    2009-11-05

    Born-Oppenheimer direct dynamics classical trajectory simulations of bimolecular collisions of PETN molecules have been performed to investigate the fundamental mechanisms of hypervelocity chemistry relevant to initiating reactions immediately behind the shock wavefront in energetic molecular crystals. The solid-state environment specifies the initial orientations of colliding molecules. The threshold velocities for initiating chemistry for a variety of crystallographic orientations were correlated with available experimental data on anisotropic shock sensitivity of PETN. Collisions normal to the planes (001) and (110) were found to be most sensitive with threshold velocities on the order of characteristic particle velocities in detonating PETN. The production of NO2 is the dominant reaction pathway in most of the reactive cases. The simulations show that the reactive chemistry, driven by dynamics rather than temperature during hypervelocity collisions, can occur at a very short time scale (10(-13) s) under highly nonequilibrium conditions.

  17. Plasma operation with an all metal first-wall: Comparison of an ITER-like wall with a carbon wall in JET

    NASA Astrophysics Data System (ADS)

    Matthews, G. F.; Jet Efda Contributors; ASDEX-Upgrade Team

    2013-07-01

    Installation of the ITER-like Wall (ILW) in JET, has allowed a direct comparison of operation with all carbon plasma facing components (PFCs) to an all metal beryllium/tungsten first-wall under otherwise nearly identical conditions. The JET results are compared with experience from ASDEX-Upgrade where there was a gradual change to a full tungsten first-wall over an extended period. The scope of this review ranges from experience with machine conditioning, impurities and breakdown to material migration, fuel retention, disruptions, impact on operational space, energy confinement and compatibility with impurity seeding. Significant changes are reported, not only in the physics directly related to plasma-surface interactions but also to the main plasma which is strongly affected in unexpected ways, impacting many aspects of tokamak operation.

  18. Distributed energy store powered railguns for hypervelocity launch

    NASA Astrophysics Data System (ADS)

    Maas, Brian L.; Bauer, David P.; Marshall, Richard A.

    1993-01-01

    Highly distributed power supplies are proposed as a basis for current difficulties with hypervelocity railgun power-supply compactness. This distributed power supply configuration reduces rail-to-rail voltage behind the main armature, thereby reducing the tendency for secondary armature current formation; secondary current elimination is essential for achieving the efficiencies associated with muzzle velocity above 6 km/sec. Attention is given to analytical and experimental results for two distributed energy storage schemes.

  19. Hypervelocity launch capabilities to over 10 km/s

    SciTech Connect

    Chhabildas, L.C.

    1991-01-01

    Very high pressure and acceleration is necessary to launch flier plates to hypervelocities. In addition, the high pressure loading must be uniform, structured, and shockless, i.e., time-dependent to prevent the flier plate from either fracturing or melting. In this paper, a novel technique is described which allows the use of megabar level loading pressures, and 10{sup 9} g acceleration to launch intact flier plates to velocities of 12.2 km/s. 32 refs., 2 figs.

  20. Analysis of the NASA Shuttle Hypervelocity Impact Database

    DTIC Science & Technology

    2003-09-01

    A statistical analysis of the NASA Space Shuttle Hypervelocity Impact Database to find correlations between meteoroid and orbital debris (M/OD...Flexible Reusable Surface Insulation (FRSI) data, In an effort to characterize and evaluate the meteoroid and orbital debris (M/OD) environment in low...determines whether the impactor was a naturally occurring meteoroid or man-made orbital debris , as well as the impactor’s size and impact velocity, From

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, Jianqiao; Song, Weidong; Ning, Jianguo

    2014-08-01

    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.

  3. 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.

  4. 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.

  5. Calorimetric Aerogel Collectors/Detectors of Hypervelocity Dust Grains

    NASA Astrophysics Data System (ADS)

    Dominguez, G.; Westphal, A. J.; Phillips, M. L. F.; Jones, S. M.

    Distinguishing between lower velocity (<8 km/s) orbital debris impacts and higher velocity extraterrestrial particles collected in aerogels was the primary driver behind our development of calorimetric aerogels. While low-density aerogels have been shown to be superior at maximizing the survival of captured hypervelocity projectiles, reconstructing the impact velocity has not been possible. We have previously demonstrated that the shock heating experienced by Gd:Tb doped alumina aerogels results in the production of permanently fluorescent impact cavities. In addition, we have shown that the amount of induced (with UV illumination) fluorescence correlates with the kinetic energy of the captured projectile. Improvements in our production capabilities have recently allowed us to measure, using a Ti-doped Si/Al aerogel, the intrinsic resolution of using this technique to reconstruct the velocity of captured hypervelocity projectiles. We are currently exploring composition space in order to optimize the sensitivity and mechanical properties of these collector/detectors. We report on the results from our latest round of hypervelocity tests as well as the expected collection statistics of deploying a 3 square meter array of calorimetric aerogels in low-Earth-orbit (LEO).

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Comparison of propagation- and grating-based x-ray phase-contrast imaging techniques with a liquid-metal-jet source

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    X-ray phase-contrast imaging has been developed as an alternative to conventional absorption imaging, partly for its dose advantage over absorption imaging at high resolution. Grating-based imaging (GBI) and propagation-based imaging (PBI) are two phase-contrast techniques used with polychromatic laboratory sources. We compare the two methods by experiments and simulations with respect to required dose. A simulation method based on the projection approximation is designed and verified with experiments. A comparison based on simulations of the doses required for detection of an object with respect to its diameter is presented, showing that for monochromatic radiation, there is a dose advantage for PBI for small features but an advantage for GBI at larger features. However, GBI suffers more from the introduction of polychromatic radiation, in this case so much that PBI gives lower dose for all investigated feature sizes. Furthermore, we present and compare experimental images of biomedical samples. While those support the dose advantage of PBI, they also highlight the GBI advantage of quantitative reconstruction of multimaterial samples. For all experiments a liquid-metal-jet source was used. Liquid-metal-jet sources are a promising option for laboratory-based phase-contrast imaging due to the relatively high brightness and small spot size.

  16. Response of spacecraft window materials to hypervelocity projectile impact

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1991-01-01

    This paper presents the results of an investigation of the response of window materials to hypervelocity projectile impact. Window impact damage is characterized according to the nature and extent of surface and internal damage. Analysis of the test data indicates that, for single-pane specimens, the extent of the damage to the test specimens can be written as functions of the impact parameters of the original projectile and the geometric and material properties of the projectile/ window system. These functions can be used to perform parameter-sensitivity studies and to evaluate hypothetical design applications and configurations.

  17. Hypervelocity accelerators with electro-thermo-chemical reaction

    NASA Astrophysics Data System (ADS)

    Ikuta, Kazunari

    1991-08-01

    A novel kind of electro-thermo-chemical (ETC) launcher for the acceleration of multikilogram-size projectiles to hypervelocity is proposed. The novel launcher concept utilizes the hot hydrogen gas generated by the chemical interaction between water and aluminum in order to accelerate the projectiles to a thermal velocity close to that of the light gas. This interaction is triggered by the Joule heating of the aluminum wire in water. Two possible designs for the accelerator concept are considered in detail. Further acceleration of the projectile near the muzzle is also discussed.

  18. Hypervelocity Impact on Interfaces: A Molecular-Dynamics Simulations Study

    NASA Astrophysics Data System (ADS)

    Bachlechner, Martina E.; Owens, Eli T.; Leonard, Robert H.; Cockburn, Bronwyn C.

    2008-03-01

    Silicon/silicon nitride interfaces are found in micro electronics and solar cells. In either application the mechanical integrity of the interface is of great importance. Molecular-dynamics simulations are performed to study the failure of interface materials under the influence of hypervelocity impact. Silicon nitride plates impacting on silicon/silicon nitride interface targets of different thicknesses result in structural phase transformation and delamination at the interface. Detailed analyses of atomic velocities, bond lengths, and bond angles are used to qualitatively examine the respective failure mechanisms.

  19. Langley proposed advanced hypervelocity aerophysics facility - A status report

    NASA Technical Reports Server (NTRS)

    Witcofski, Robert D.; Scallion, William I.

    1989-01-01

    A ground-based facility capable of performing flight tests on relatively large highly instrumented models and scaled vehicle components at velocities and densities representative of a hypervelocity flight in earth and planetary atmospheres is reviewed. This facility proposed by the Langley Research Center is based on a launcher, a test chamber, and a model impact/deceleration chamber. It would initially utilize existing light-gas gun launcher technology scaled to 4 times present launcher size. It is planned to enhance its velocity and model size capability either by an electromagnetic launcher or a ram accelerator.

  20. Effects of oxygen dissociation on hypervelocity combustion experiments

    NASA Technical Reports Server (NTRS)

    Bakos, R. J.; Morgan, R. G.; Tamagno, J.

    1992-01-01

    Results are presented of a comparative experimental study conducted to measure the effects of the test gas oxygen dissociation produced in reflected shock tunnels on hypervelocity combustion. An identical combustor model was tested in a reflected shock tunnel with test gas containing about 50 pct by mass of oxygen in dissociated form, as either nitric oxide or atomic oxygen, and in an expansion tube with test gas having negligible dissociated oxygen. Comparisons are made at two test conditions that are energy equivalent to flight conditions at Mach 13.5 and 17.

  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. Jetting tool

    SciTech Connect

    Szarka, D.D.; Schwegman, S.L.

    1991-07-09

    This patent describes an apparatus for hydraulically jetting a well tool disposed in a well, the well tool having a sliding member. It comprises positioner means for operably engaging the sliding member of the well tool; and a jetting means, connected at a rotatable connection to the positioner means so that the jetting means is rotatable relative to the positioner means and the well tool, for hydraulically jetting the well tool as the jetting means is rotated relative thereto.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Discrete Particle Method for Simulating Hypervelocity Impact Phenomena

    PubMed Central

    Watson, Erkai; Steinhauser, Martin O.

    2017-01-01

    In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI) phenomena which is based on the Discrete Element Method (DEM). Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 kms−1. We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact. We model a typical HVI experiment configuration where a sphere strikes a thin plate and investigate the properties of the resulting debris cloud. We provide a quantitative computational analysis of the resulting debris cloud caused by impact and a comprehensive parameter study by varying key parameters of our model. We compare our findings from the simulations with recent HVI experiments performed at our institute. Our findings are that the DEM method leads to very stable, energy–conserving simulations of HVI scenarios that map the experimental setup where a sphere strikes a thin plate at hypervelocity speed. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength. PMID:28772739

  11. Graphene Nano-Composites for Hypervelocity Impact Applications

    NASA Astrophysics Data System (ADS)

    Manasrah, Alharith

    The Low Earth Orbit (LEO) is a harsh environment cluttered with natural meteoroids and man-made debris, which can travel at velocities approaching 15 km/s. Most space activities within the LEO will encounter this environment. Thus, the spacecraft and its hardware must be designed to survive debris impact. This research introduces new procedures to produce a nano-composite material with mortar-brick nano-structure inspired from nacre. Nacre-like composites were successfully manufactured, based on three host polymers, with a wide range of graphene concentrations. The manufactured exfoliated graphene nano-platelet, embedded in a host polymer, provided good potential for enhancement of the hypervelocity impact (HVI) shield resistance. The nano-composites are suggested for use as a coating. Moreover, explicit dynamic finite element studies were conducted for further investigation of the hypervelocity impact of the graphene-based coatings in order to understand the effect of the coating on the crater formation and the exit velocity. This dissertation presents the results of the characterization and numerical sensitivity study of the developed material parameters. The numerical simulations were performed by implementing Autodyn smooth particle hydrodynamics. This study provides innovative, low-weight shielding enhancements for spacecraft, as well as other promising applications for the manufactured nano-composites.

  12. 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.

  13. Discrete Particle Method for Simulating Hypervelocity Impact Phenomena.

    PubMed

    Watson, Erkai; Steinhauser, Martin O

    2017-04-02

    In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI) phenomena which is based on the Discrete Element Method (DEM). Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 kms(-1). We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact. We model a typical HVI experiment configuration where a sphere strikes a thin plate and investigate the properties of the resulting debris cloud. We provide a quantitative computational analysis of the resulting debris cloud caused by impact and a comprehensive parameter study by varying key parameters of our model. We compare our findings from the simulations with recent HVI experiments performed at our institute. Our findings are that the DEM method leads to very stable, energy-conserving simulations of HVI scenarios that map the experimental setup where a sphere strikes a thin plate at hypervelocity speed. Our chosen interaction model works particularly well in the velocity range where the local stresses caused by impact shock waves markedly exceed the ultimate material strength.

  14. Electrostatic method to accelerate nanoshells to extreme hypervelocity

    NASA Astrophysics Data System (ADS)

    Wang, Zhehui; Kline, J. L.

    2003-08-01

    Using an acceleration voltage of less than a few hundred kilovolts, it is unlikely that a charged solid object larger than a few micron (10-6 m) in all three dimensions can be accelerated to more than 10 km/s. Quasi-two-dimensional (Q2D) objects are unique forms of matter with two macroscopic dimensions, while the third approaches atomic dimensions. Well-known examples of Q2D objects are thin films. Another example of a Q2D object will be a sphere with a nm thick shell (nanoshell). In this letter, it is predicted that nanoshells can be accelerated to 100 km/s (extreme hypervelocity, or EHV) and above using the electrostatic method. The maximum velocity is limited by field emission and material strength. The two limits only allow a certain number of charges on a nanoshell before it starts to emit ions or electrons, or to break. "Table-top" EHV nanoshell beams can be used for high-temperature plasma diagnostics and fueling. EHV nanoshells can also be used to study hypervelocity-impact phenomena in a momentum space not accessible in the past.

  15. Flash characteristics of plasma induced by hypervelocity impact

    SciTech Connect

    Zhang, Kai; Long, Renrong E-mail: qmzhang@bit.edu.cn; Zhang, Qingming E-mail: qmzhang@bit.edu.cn; Xue, Yijiang; Ju, Yuanyuan

    2016-08-15

    Using a two-stage light gas gun, a series of hypervelocity impact experiments was conducted in which 6.4-mm-diameter spherical 2024-aluminum projectiles impact 23-mm-thick targets made of the same material at velocities of 5.0, 5.6, and 6.3 km/s. Both an optical pyrometer composed of six photomultiplier tubes and a spectrograph were used to measure the flash of the plasma during hypervelocity impact. Experimental results show that, at a projectile velocity of 6.3 km/s, the strong flash lasted about 10 μs and reached a temperature of 4300 K. Based on the known emission lines of AL I, spectral methods can provide the plasma electron temperature. An electron-temperature comparison between experiment and theoretical calculation indicates that single ionization and secondary ionization are the two main ionizing modes at velocities 5.0–6.3 km/s.

  16. 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.

  17. 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.

  18. 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.

  19. Analysis of rotating collectors from the private region of JET 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.; Matthews, G. F.; Brezinsek, S.

    2015-08-01

    Rotating collectors are used in JET to provide time-resolved measurements of erosion and redeposition of vessel materials. The silicon collecting discs rotate behind an aperture, driven by pulsing of the toroidal magnetic field, with the deposits analysed ex-situ by nuclear reaction analysis. The angular dependence of deposition is mapped to discharge number using the B-field history, allowing the influence of different plasma configurations and parameters to be investigated. A simple geometrical model using sputtering and reflection from the strike point has qualitatively reproduced the deposition found on collectors located under the central divertor tile and facing towards the inner strike point. The beryllium deposition on the ITER-like wall (ILW) collector showed an order of magnitude reduction in deposition compared to carbon deposition on the JET-C collector. This decreased deposition is attributed to low long range divertor transport due to reduced chemical sputtering/erosion and codeposition of beryllium relative to carbon.

  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. 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.

  2. 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.

  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. 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.

  5. Hypervelocity impact effects on solar cells

    NASA Astrophysics Data System (ADS)

    Rose, M. Frank

    1992-09-01

    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.

  6. 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

  7. 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.

  8. 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.

  9. Using Hydrocode Modelling to Track Ejecta from Oblique Hypervelocity Impacts onto Glass

    NASA Astrophysics Data System (ADS)

    Price, M. C.; Burchell, M.

    2012-03-01

    Hydrocode modelling has been implemented to track the ejecta from hypervelocity impacts of oblique impactors onto glass. This supports the ongoing Stardust ISPE as a method to aid discrimination between spacecraft secondary impacts and IDP/ISPs.

  10. Subsurface Deformation of Experimental Hypervelocity Impacts in Non-Porous Targets

    NASA Astrophysics Data System (ADS)

    Winkler, R.; Poelchau, M. H.; Schäfer, F.; Kenkmann, T.

    2016-08-01

    Experimental hypervelocity impacts in quartzite and marble targets under similar impact conditions reveal great differences in impact induced deformation mechanisms, due to the dynamic mechanical properties of the main rock-forming minerals.

  11. 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.

  12. Fuzzy jets

    DOE PAGES

    Mackey, Lester; Nachman, Benjamin; Schwartzman, Ariel; ...

    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 variablesmore » 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

  13. Fuzzy jets

    SciTech Connect

    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.

  14. 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.

  15. Shock detachment process on cones in hypervelocity flows

    NASA Astrophysics Data System (ADS)

    Leyva, Ivett Alejandra

    1999-11-01

    The shock detachment process on cones in hypervelocity flows is one of the most sensitive flows to relaxation effects. The critical angle for shock detachment under frozen conditions can be very different from the critical angle under chemical and thermal equilibrium. The rate of increase of the detachment distance with cone angle is also affected by the relaxation rate. The purpose of this study is to explain the effects of nonequilibrium on the shock detachment distance and its growth rate on cones in hypervelocity flows. The study consists of an experimental and a computational program. The experimental part has been carried out at Caltech's hypervelocity reflected shock tunnel. Six free-stream conditions were chosen, using both N2 and CO2 as test gases. The experimental data obtained are holographic interferograms, surface temperature, and pressure measurements. The code employed for the numerical simulations is a Navier-Stokes solver that can account for thermal and chemical nonequilibrium in axisymmetric flows. The data obtained for the shock detachment distance confirms a previous theoretical model that predicts the detachment distance will grow more slowly for relaxing flows than for frozen or equilibrium flows. This difference is due to the behavior of the sonic line inside the shock layer. Different growth rates result when the detachment distance is controlled by the diameter of the cone (frozen and equilibrium cases) than when it is controlled by the relaxation length (nonequilibrium flows). The behavior of the detachment distance from the frozen to equilibrium limits for a given cone half-angle and free-stream condition has also been studied. It was confirmed that the ratio of the detachment distance to the cone diameter is constant in the two extremes and rapidly switches from one value to the other for cone diameters of about 2 cm to 16 cm. The experimental interferograms are also compared with numerical ones in terms of the detachment distance, the

  16. Navy Lasers, Railgun, and Hypervelocity Projectile: Background and Issues for Congress

    DTIC Science & Technology

    2016-05-27

    certain wavelengths of light (i.e., “sweet spots” in the electromagnetic spectrum ) where atmospheric absorption by water vapor is markedly reduced...surface ships to defend themselves against enemy missiles—solid state lasers (SSLs), the electromagnetic railgun (EMRG), and the hypervelocity... electromagnetic railgun (EMRG), and the hypervelocity projectile (HVP). 1 Any one of these new weapon technologies, if successfully developed and deployed

  17. Navy Lasers, Railgun, and Hypervelocity Projectile: Background and Issues for Congress

    DTIC Science & Technology

    2016-03-18

    of light (i.e., “sweet spots” in the electromagnetic spectrum ) where atmospheric absorption by water vapor is markedly reduced. Lasers can be Navy...surface ships to defend themselves against enemy missiles—solid state lasers (SSLs), the electromagnetic railgun (EMRG), and the hypervelocity...missiles—solid state lasers (SSLs), the electromagnetic railgun (EMRG), and the hypervelocity projectile (HVP). 1 Any one of these new weapon

  18. Navy Lasers, Railgun, and Hypervelocity Projectile: Background and Issues for Congress

    DTIC Science & Technology

    2016-10-21

    wavelengths of light (i.e., “sweet spots” in the electromagnetic spectrum ) where atmospheric absorption by water vapor is markedly reduced. Lasers can be...surface ships to defend themselves against enemy missiles—solid state lasers (SSLs), the electromagnetic railgun (EMRG), and the hypervelocity...SSLs), the electromagnetic railgun (EMRG), and the hypervelocity projectile (HVP). 1 Any one of these new weapon technologies, if successfully

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

    NASA Astrophysics Data System (ADS)

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

    1993-04-01

    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

  20. 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

  1. 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

  2. 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

  3. Study on microwave emission mechanisms on the basis of hypervelocity impact experiments on various target plates

    NASA Astrophysics Data System (ADS)

    Ohnishi, H.; Chiba, S.; Soma, E.; Ishii, K.; Maki, K.; Takano, T.; Hasegawa, S.

    2007-06-01

    It was formerly confirmed by experiment that hypervelocity impacts on aluminum plates cause microwave emission. In this study, we have carried out experiments in order to clarify the mechanism of the emission. The microwave is detected by heterodyne detection scheme at 22 and 2 GHz with an intermediate frequency bandwidth of 500 and 120 MHz, respectively. A nylon projectile is accelerated using a light-gas gun to impact a target. First, aluminum plates with ten different thicknesses ranging from 1 to 40 mm were used as a target, and microwave signals were detected. The experimental results are statistically analyzed assuming a Gaussian distribution of the emitted power. The standard deviation of pulse voltage is calculated to show the existence of two kinds of signals: sharp pulse and thermal noise. It is shown that the emitted energy and the dispersion have a relation with the extent of the target destruction. Next, nylon projectiles are impacted on different metals such as aluminum, iron, and copper. These results suggest that microcracks are essential to microwave emission. Finally, in order to clarify the mechanism of charging and discharging across the microcracks, the experimental results are compared with this model for the following factors: (1) the thermally excited electrons and the emitted power, and (2) the bond dissociation energy of target material and emitted power. The analytical results suggest that electrons are excited thermally and by transition from a crystalline state to an atomic state.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    SciTech Connect

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

    2006-10-15

    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 (n{sub e}{approx_equal}10{sup 18} cm{sup -3}) and low temperature (a few eV) deuterium plasma, ejected by JxB forces which provide drag on the dust particles in its path. The dust will be entrained by the plasma to velocities of 1-30 km/s, depending on the dust mass. Carbon dust particles will be used, with diameters from 1 to 50 {mu}m. The key components of the plasmadynamic accelerator are a coaxial plasma gun operated at 10 kV (with an estimated discharge current of 200 kA), a dust dispenser activated by a piezoelectric transducer, and power and remote-control systems.

  9. 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.

  10. 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.

  11. Applications of the ram accelerator to hypervelocity aerothermodynamic testing

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Knowlen, C.; Hertzberg, A.

    1992-01-01

    A ram accelerator used as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerodynamics research is presented. It is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled down a stationary tube filled with a tailored combustible gas mixture. Ram accelerator operation has been demonstrated at 39 mm and 90 mm bores, supporting the proposition that this launcher concept can be scaled up to very large bore diameters of the order of 30-60 cm. It is concluded that high quality data obtained from the tube wall and projectile during the aceleration process itself are very useful for understanding aerothermodynamics of hypersonic flow in general, and for providing important CFD validation benchmarks.

  12. Applications of the ram accelerator to hypervelocity aerothermodynamic testing

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Knowlen, C.; Hertzberg, A.

    1992-01-01

    A ram accelerator used as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerodynamics research is presented. It is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled down a stationary tube filled with a tailored combustible gas mixture. Ram accelerator operation has been demonstrated at 39 mm and 90 mm bores, supporting the proposition that this launcher concept can be scaled up to very large bore diameters of the order of 30-60 cm. It is concluded that high quality data obtained from the tube wall and projectile during the aceleration process itself are very useful for understanding aerothermodynamics of hypersonic flow in general, and for providing important CFD validation benchmarks.

  13. 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.

  14. Mass spectrometry of hyper-velocity impacts of organic micrograins.

    PubMed

    Srama, Ralf; Woiwode, Wolfgang; Postberg, Frank; Armes, Steven P; Fujii, Syuji; Dupin, Damien; Ormond-Prout, Jonathan; Sternovsky, Zoltan; Kempf, Sascha; Moragas-Klostermeyer, Georg; Mocker, Anna; Grün, Eberhard

    2009-12-01

    The study of hyper-velocity impacts of micrometeoroids is important for the calibration of dust sensors in space applications. For this purpose, submicron-sized synthetic dust grains comprising either polystyrene or poly[bis(4-vinylthiophenyl)sulfide] were coated with an ultrathin overlayer of an electrically conductive organic polymer (either polypyrrole or polyaniline) and were accelerated to speeds between 3 and 35 km s(-1) using the Heidelberg Dust Accelerator facility. Time-of-flight mass spectrometry was applied to analyse the resulting ionic impact plasma using a newly developed Large Area Mass Analyser (LAMA). Depending on the projectile type and the impact speed, both aliphatic and aromatic molecular ions and cluster species were identified in the mass spectra with masses up to 400 u. Clusters resulting from the target material (silver) and mixed clusters of target and projectile species were also observed. Impact velocities of between 10 and 35 km s(-1) are suitable for a principal identification of organic materials in micrometeoroids, whereas impact speeds below approximately 10 km s(-1) allow for an even more detailed analysis. Molecular ions and fragments reflect components of the parent molecule, providing determination of even complex organic molecules embedded in a dust grain. In contrast to previous measurements with the Cosmic Dust Analyser instrument, the employed LAMA instrument has a seven times higher mass resolution--approximately 200--which allowed for a detailed analysis of the complex mass spectra. These fundamental studies are expected to enhance our understanding of cometary, interplanetary and interstellar dust grains, which travel at similar hyper-velocities and are known to contain both aliphatic and aromatic organic compounds. Copyright 2009 John Wiley & Sons, Ltd.

  15. 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.

  16. 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.

  17. Shock detachment process on cones in hypervelocity flows

    NASA Astrophysics Data System (ADS)

    Leyva, Ivett A.

    1999-11-01

    The shock detachment process on cones in hypervelocity flows is one of the most sensitive flows to relaxation effects. The critical angle for shock detachment under frozen conditions can be very different from the critical angle under chemical and thermal equilibrium. The rate of increase of the detachment distance with cone angle is also affected by the relaxation rate. The purpose of this study is to explain the effects of nonequilibrium on the shock detachment distance and its growth rate on cones in hypervelocity flows. The study consists of an experimental and a computational program. The experimental part has been carried out at Caltech's hypervelocity reflected shock tunnel (T5). Six different free-stream conditions have been chosen, four using N2 as the test gas and two using CO2. About 170 shots were performed on 24 cones. The cones range in diameter from 2 cm to 16 cm with half-angles varying from 55° to 75°. The experimental data obtained are holographic interferograms of every shot, and surface temperature and pressure measurements for the bigger cones. Extensive numerical simulations were made for the N2 flows and some were also made for the CO2 flows. The code employed is a Navier-Stokes solver that can account for thermal and chemical nonequilibrium in axisymmetric flows. The experimental and computational data obtained for the shock detachment distance confirms a previous theoretical model that predicts the detachment distance will grow more slowly for relaxing flows than for frozen or equilibrium flows. This difference is explained in terms of the behavior of the sonic line inside the shock layer. Different growth rates result when the detachment distance is controlled by the diameter of the cone (frozen and equilibrium cases) than when it is controlled by the extent of the relaxation zone inside the shock layer (nonequilibrium flows). The experimental data are also complemented with computational data to observe the behavior of the detachment

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

    NASA Astrophysics Data System (ADS)

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

    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

  19. 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

  20. 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

  1. Improved Hypervelocity Plasma Characterization Using Bremsstrahlung Optical Continuum Model

    NASA Astrophysics Data System (ADS)

    Hew, Y. M.

    2016-12-01

    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 emission produced by this plasma can potentially lead to electrical anomalies within the spacecraft. 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 generated during a ground-based hypervelocity impact is long expected by many researchers to contain the characteristics of the impact generated plasma, such as plasma temperature and density. The most common approach in the literature is to use the spectroscopic measurement of the impact flash and assume the impact flash emission to be a perfect blackbody spectrum to estimate the brightness temperature using Plank's law which relies on the assumption of continuum emission and the local thermodynamics equilibrium within the emitter. However, many recent experimental results and literature have shown the emission spectrum of the impact flash to evolve from continuum spectrum to line spectrum within the very first few microseconds after impact, and significant levels of deviation from blackbody emission spectrum even in the continuum emission phase. This presentation use Bremsstrahlung emission model as an augmented approach to characterize the impact plasma. Bremsstrahlung radiation is a generalized thermal radiation where the optical emission is produced by charged particles acceleration. As the plasma optical thickness increases, the Bremsstrahlung spectrum approaches the Blackbody spectrum. Thus, the Bremsstrahlung spectrum provides a better approximation of the measured continuum emission

  2. LDEF's map experiment foil perforations yield hypervelocity impact penetration parameters

    NASA Technical Reports Server (NTRS)

    Mcdonnell, J. A. M.

    1992-01-01

    The space exposure of LDEF for 5.75 years, forming a host target in low earth orbit (LEO) orbit to a wide distribution of hypervelocity particulates of varying dimensions and different impact velocities, has yielded a multiplicity of impact features. Although the projectile parameters are generally unknown and, in fact not identical for any two impacts on a target, the great number of impacts provides statistically meaningful basis for the valid comparison of the response of different targets. Given sufficient impacts for example, a comparison of impact features (even without knowledge of the project parameters) is possible between: (1) differing material types (for the same incident projectile distribution); (2) differing target configurations (e.g., thick and thin targets for the same material projectiles; and (3) different velocities (using LDEF's different faces). A comparison between different materials is presented for infinite targets of aluminum, Teflon, and brass in the same pointing direction; the maximum finite-target penetration (ballistic limit) is also compared to that of the penetration of similar materials comprising of a semi-infinite target. For comparison of impacts on similar materials at different velocities, use is made of the pointing direction relative to LDEF's orbital motion. First, however, care must be exercised to separate the effect of spatial flux anisotropies from those resulting from the spacecraft velocity through a geocentrically referenced dust distribution. Data comprising thick and thin target impacts, impacts on different materials, and in different pointing directions is presented; hypervelocity impact parameters are derived. Results are also shown for flux modeling codes developed to decode the relative fluxes of Earth orbital and unbound interplanetary components intercepting LDEF. Modeling shows the west and space pointing faces are dominated by interplanetary particles and yields a mean velocity of 23.5 km/s at LDEF

  3. 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.

  4. 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.

  5. Passive hypervelocity boundary layer control using an ultrasonically absorptive surface

    NASA Astrophysics Data System (ADS)

    Rasheed, Adam

    A series of exploratory boundary layer transition experiments was performed on a sharp 5.06 degree half-angle round cone at zero angle-of-attack in the T5 Hypervelocity Shock Tunnel in order to test a novel hypersonic boundary layer control scheme. Recently performed linear stability analyses suggested that transition could be delayed in hypersonic boundary layers by using an ultrasonically absorptive surface that would damp the second mode (Mack mode). The cone used in the experiments was constructed with a smooth surface on half the cone (to serve as a control) and an acoustically absorptive porous surface on the other half. It was instrumented with flush-mounted thermocouples to detect the transition location. Test gases investigated included nitrogen and carbon dioxide at Mach 5 with specific reservoir enthalpy ranging from 1.3 MJ/kg to 13.0 MJ/kg and reservoir pressure ranging from 9.0 MPa to 50.0 MPa. Detailed comparisons were performed to insure that previous results obtained in similar boundary layer transition experiments (on a regular smooth surface) were reproduced and the results were extended to examine the effects of the porous surface. These experiments indicated that the porous surface was highly effective in delaying transition provided that the hole size was significantly smaller than the viscous length scale.

  6. Passive hypervelocity boundary layer control using an acoustically absortive surface

    NASA Astrophysics Data System (ADS)

    Rasheed, Adam

    A series of exploratory boundary layer transition experiments was performed on a sharp 5.06 degree half-angle round cone at zero angle-of-attack in the T5 Hypervelocity Shock Tunnel in order to test a novel hypersonic boundary layer control scheme. Recently performed linear stability analyses suggested that transition could be delayed in hypersonic boundary layers by using an ultrasonically absorptive surface that would damp the second mode (Mack mode). The cone used in the experiments was constructed with a smooth surface on half the cone (to serve as a control) and an acoustically absorptive porous surface on the other half. It was instrumented with flush-mounted thermocouples to detect the transition location. Test gases investigated included nitrogen and carbon dioxide at M = 5 with specific reservoir enthalpy ranging from 1.3 MJ/kg to 13.0 MJ/kg and reservoir pressure ranging from 9.0 MPa to 50.0 MPa. Detailed comparisons were performed to insure that previous results obtained in similar boundary layer transition experiments (on a regular smooth surface) were reproduced and the results were extended to examine the effects of the porous surface. These experiments indicated that the porous surface was highly effective in delaying transition provided that the hole size was significantly smaller than the viscous length scale.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. RUNAWAY STARS, HYPERVELOCITY STARS, AND RADIAL VELOCITY SURVEYS

    SciTech Connect

    Bromley, Benjamin C.; Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J. E-mail: skenyon@cfa.harvard.ed E-mail: mgeller@cfa.harvard.ed

    2009-12-01

    Runaway stars ejected from the Galactic disk populate the halo of the Milky Way. To predict the spatial and kinematic properties of runaways, we inject stars into a Galactic potential, compute their trajectories through the Galaxy, and derive simulated catalogs for comparison with observations. Runaways have a flattened spatial distribution, with higher velocity stars at Galactic latitudes less than 30{sup 0}. Due to their shorter stellar lifetimes, massive runaway stars are more concentrated toward the disk than low mass runaways. Bound (unbound) runaways that reach the halo probably originate from distances of 6-12 kpc (10-15 kpc) from the Galactic center, close to the estimated origin of the unbound runaway star HD 271791. Because runaways are brighter and have smaller velocities than hypervelocity stars (HVSs), radial velocity surveys are unlikely to confuse runaway stars with HVSs. We estimate that at most one runaway star contaminates the current sample. We place an upper limit of 2% on the fraction of A-type main-sequence stars ejected as runaways.

  16. 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.

  17. Numerical investigation of combustion field of hypervelocity scramjet engine

    NASA Astrophysics Data System (ADS)

    Zhang, Shikong; Li, Jiang; Qin, Fei; Huang, Zhiwei; Xue, Rui

    2016-12-01

    A numerical study of the ground testing of a hydrogen-fueled scramjet engine was undertaken using the commercial computational-fluid-dynamics code CFD++. The simulated Mach number was 12. A 7-species, 9-reaction-step hydrogen-air chemistry kinetics system was adopted for the Reynolds-averaged Navier-Stokes simulation. The two-equation SST turbulence model, which takes into account the wall functions, was used to handle the turbulence-chemistry interactions. The results were validated by experimentally measuring the wall pressure distribution, and the values obtained proved to be in good agreement. The flow pattern at non-reaction/reaction is presented, as are the results of analyzing the supersonic premix/non-premix flame structure, the reaction heat release distribution in different modes, and the change in the equivalence ratio. In this study, we realize the working mode of a hypervelocity engine and provide some suggestions for the combustion organization of the engine as well as offer insight into the potential for exploiting the processes of combustion and flow.

  18. Imaging system for hypervelocity dust injection diagnostic on NSTX

    SciTech Connect

    Dorf, L. A.; Roquemore, A. L.; Wurden, G. A.; Ticos, C. M.; Wang Zhehui

    2006-10-15

    The novel hypervelocity dust injection diagnostic will facilitate our understanding of basic aspects of dust-plasma interaction and magnetic field topology in fusion plasma devices, by observing 'comet tails' associated with the injected micron-size dust particles. A single projection of the tail onto an image plane will not provide sufficient information; therefore, we plan to use two views, with intensified DiCam-Pro cameras on two NSTX ports. Each camera can furnish up to five overlaying sequential images with gate times greater than 3 ns and 1280x1024 pixel resolution. A coherent fiber bundle with 1500x1200 fibers will relay the image from an imaging lens installed directly on the port to the camera optics. The lens receives light from the outer portion of the NSTX cross section and focuses a 1 cm tail onto at least 60 fibers for adequate resolution. The estimated number of photons received by the camera indicates signal-to-noise ratios of 10{sup 2}-10{sup 4}, with the use of a 10 nm bandwidth filter. The imaging system with one camera was successfully tested on NSTX in 2005. Photographing lithium pellets yielded bright and distinctive pictures of the tails nearly aligned with B lines. We also observed that the bright 'filaments' - plasma cords with high density and temperature - are present in both top and bottom portions of the machine.

  19. Theory of an Electromagnetic Mass Accelerator for Achieving Hypervelocities

    NASA Technical Reports Server (NTRS)

    Thom, Karlheinz; Norwood, Joseph., Jr.

    1961-01-01

    It is shown that for any electromagnetic accelerator which employs an electromagnetic force for driving the projectile and uses the projectile as the heat sink for the energy dissipated in it by ohmic heating, the maximum velocity attainable without melting is a function of the mass of the projectile. Therefore, for hypervelocities a large projectile mass is required and thus a power supply of very large capacity is necessary. It is shown that the only means for reducing the power requirement is maximizing the gradient of the mutual inductance. In the scheme of the sliding-coil accelerator investigated herein, the gradient of the mutual inductance is continuously maintained at a high value. It is also shown that for minimum length of the accelerator, the current must be kept constant despite the rise in induced voltage during acceleration. The use of a capacitor bank as an energy source with the condition that the current be kept constant is investigated. Experiments at low velocities are described.

  20. Constraining the Milky Way mass with hypervelocity stars

    NASA Astrophysics Data System (ADS)

    Fragione, G.; Loeb, A.

    2017-08-01

    Although a variety of techniques have been employed for determining the Milky Way dark matter halo mass distribution, the range of allowed masses spans both light and heavy values. Knowing the precise mass of our Galaxy is important for placing the Milky Way in a cosmological ΛCDM context. We show that hypervelocity stars (HVSs) ejected from the center of the Milky Way galaxy can be used to constrain the mass of its dark matter halo. We use the asymmetry in the radial velocity distribution of halo stars due to escaping HVSs, which depends on the halo potential (escape speed) as long as the round trip orbital time is shorter than the stellar lifetime, to discriminate between different models for the Milky Way gravitational potential. Adopting a characteristic HVS travel time of 330 Myr, which corresponds to the average mass of main sequence HVSs, we find that current data favors a mass for the Milky Way in the range (1.2 - 1.9) ×1012M⊙ .

  1. Hypervelocity Impact Test Facility: A gun for hire

    NASA Astrophysics Data System (ADS)

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

    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.

  2. Hypervelocity impacts into porous graphite: experiments and simulations

    NASA Astrophysics Data System (ADS)

    Hébert, D.; Seisson, G.; Rullier, J.-L.; Bertron, I.; Hallo, L.; Chevalier, J.-M.; Thessieux, C.; Guillet, F.; Boustie, M.; Berthe, L.

    2017-01-01

    We present experiments and numerical simulations of hypervelocity impacts of 0.5 mm steel spheres into graphite, for velocities ranging between 1100 and 4500 m s-1. Experiments have evidenced that, after a particular striking velocity, depth of penetration no longer increases but decreases. Moreover, the projectile is observed to be trapped below the crater surface. Using numerical simulations, we show how this experimental result can be related to both materials, yield strength. A Johnson-Cook model is developed for the steel projectile, based on the literature data. A simple model is proposed for the graphite yield strength, including a piecewise pressure dependence of the Drucker-Prager form, which coefficients have been chosen to reproduce the projectile penetration depth. Comparisons between experiments and simulations are presented and discussed. The damage properties of both materials are also considered, by using a threshold on the first principal stress as a tensile failure criterion. An additional compressive failure model is also used for graphite when the equivalent strain reaches a maximum value. We show that the experimental crater diameter is directly related to the graphite spall strength. Uncertainties on the target yield stress and failure strength are estimated. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

  3. Hypervelocity impacts into porous graphite: experiments and simulations.

    PubMed

    Hébert, D; Seisson, G; Rullier, J-L; Bertron, I; Hallo, L; Chevalier, J-M; Thessieux, C; Guillet, F; Boustie, M; Berthe, L

    2017-01-28

    We present experiments and numerical simulations of hypervelocity impacts of 0.5 mm steel spheres into graphite, for velocities ranging between 1100 and 4500 m s(-1) Experiments have evidenced that, after a particular striking velocity, depth of penetration no longer increases but decreases. Moreover, the projectile is observed to be trapped below the crater surface. Using numerical simulations, we show how this experimental result can be related to both materials, yield strength. A Johnson-Cook model is developed for the steel projectile, based on the literature data. A simple model is proposed for the graphite yield strength, including a piecewise pressure dependence of the Drucker-Prager form, which coefficients have been chosen to reproduce the projectile penetration depth. Comparisons between experiments and simulations are presented and discussed. The damage properties of both materials are also considered, by using a threshold on the first principal stress as a tensile failure criterion. An additional compressive failure model is also used for graphite when the equivalent strain reaches a maximum value. We show that the experimental crater diameter is directly related to the graphite spall strength. Uncertainties on the target yield stress and failure strength are estimated.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. © 2016 The Author(s).

  4. 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.

  5. 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.

  6. 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.

  7. Phase Transitions in Simulation of Hypervelocity Impact Experiments

    NASA Astrophysics Data System (ADS)

    Povarnitsyn, Mikhail; Zakharenkov, Alexey; Khishchenko, Konstantin; Levashov, Pavel

    2009-06-01

    Hypervelocity impact experiments can give us additional information about thermodynamical properties of matter in extreme state. In this work we simulate shock--induced melting, fragmentation and vaporization in aluminum and zinc targets. A tantalum impactor strikes zinc and aluminum targets at a velocity of 10 km/s and causes melting of these materials in a shock wave. Then under intensive rarefaction the thermodynamic path crosses the liquid--vapor coexistence boundary and enters into a metastable liquid state. Liquid in a metastable state undergoes either liquid--vapor phase separation or mechanical spallation. The theory of homogeneous nucleation as well as mechanical fragmentation criterion are used to control the kinetics of these processes in our model. The first effect dominates in the vicinity of the critical point, the second one at lower temperatures and negative pressure. Phase transitions and kinetics of phase separations are taken into account using a thermodynamically complete equation of state in tabular form with stable and metastable states for all materials under consideration. It is shown that liquid--vapor properties are very important for adequate description of experiment.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. Bouncing Jets

    NASA Astrophysics Data System (ADS)

    Wadhwa, Navish; Vlachos, Pavlos; Jung, Sunghwan

    2011-11-01

    Contrary to common intuition, free jets of fluid can ``bounce'' off each other on collision in mid-air, through the effect of a lubricating air film that separates the jets. We have developed a simple experimental setup to stably demonstrate and study the non-coalescence of jets on collision. We present the results of an experimental investigation of oblique collision between two silicone oil jets, supported by a simple analytical explanation. Our focus is on elucidating the role of various physical forces at play such as viscous stresses, capillary force and inertia. A parametric study conducted by varying the nozzle diameter, jet velocity, angle of inclination and fluid viscosity reveals the scaling laws for the quantities involved such as contact time. We observed a transition from bouncing to coalescence with an increase in jet velocity and inclination angle. We propose that a balance between the contact time of jets and the time required for drainage of the trapped air film can provide a criterion for transition from non-coalescence to coalescence.

  16. 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.

  17. Phase transition effect on efficiency of screen protection against elongated hyper-velocity projectiles

    NASA Astrophysics Data System (ADS)

    Rumiantsev, B. V.; Mikhaylin, A. I.

    2017-06-01

    Parameters of an elongated hyper-velocity projectile formed by a detonation of a cumulative charge are determined. The projectile's mass, impact velocity and energy were determined. Penetration pressures are calculated by the deceleration method. Values obtained are compared with commonly known data on phase states of interacting materials - melting and partial evaporation. An elongated projectile penetration through a screen protection into a target is analyzed. Experimental data obtained reveals high efficiency of a screen protection against an elongated hypervelocity projectile in an area of interacting materials evaporation.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  19. 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.

  20. 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.

  1. Flow field investigation of atmospheric braking for high drag vehicles with forward facing jets. [in spacecraft entry

    NASA Technical Reports Server (NTRS)

    Grenich, A. F.; Woods, W. C.

    1981-01-01

    Flow field phenomena associated with a supersonic jet issuing upstream into a hypervelocity flow field were investigated experimentally in support of a new space vehicle aerobraking concept developed by Boeing for Orbital Transfer Vehicles (OTV's). Tests were made on OTV models in the NASA Langley 22 in., Mach 20 helium tunnel with jet exit Mach numbers from 1.0 to 6.18 and ballute half angles of 45 and 60 deg. Force data were taken at zero angle of attack to determine the effect of ballute angle, jet Mach number and jet flow rate on vehicle drag. Bow shock structures were examined in terms of flow steadiness to define acceptable jet flow rate regimes for use in drag modulation. Limited tests were made to obtain pressure and temperature distributions around the ballute and to determine the ballute center of pressure. Test results are presented and discussed relative to OTV application and similar previous experimental investigations.

  2. 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.

  3. Business Jet

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Citation Jet, developed by Cessna Aircraft Company, Wichita, KS, is the first business jet to employ Langley Research Center's natural laminar flow (NLF) technology. NLF reduces drag and therefore saves fuel by using only the shape of the wing to keep the airflow smooth, or laminar. This reduces friction between the air and wing, and therefore, reduces drag. NASA's Central Industrial Applications Center, Rural Enterprises, Inc., Durant, OK, its Kansas affiliate, and Wichita State University assisted in the technology transfer.

  4. 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.

  5. On The Spatial Distribution and the Origin of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Lu, Youjun; Zhang, Fupeng; Yu, Qingjuan

    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.

  6. 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).

  7. 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.

  8. Atomistic Modeling of the Hypervelocity Impact of Electrosprayed Nanodroplets

    NASA Astrophysics Data System (ADS)

    Saiz Poyatos, Fernan

    Uniform beams of nanodroplets can be electrosprayed in a vacuum by applying strong electric fields at the tip of an emitter fed with an ionic liquid. These projectiles can be electrostatically accelerated up to velocities of several kilometers per second, and directed towards the surface of a crystalline solid to produce a hypervelocity impact. The phenomenology of these nanodroplet impacts is diverse: for example, it has been observed that the associated sputtering yield is of order one; and that at high enough projectile velocity the bombardment amorphizes the surface of silicon. However there is no detailed understanding of the physical mechanisms behind these observations. The goal of this doctoral research is to correct this situation. Molecular Dynamics (MD) are employed to simulate a number of nanodroplet impacts, which in turn yields accurate thermodynamic and structural information of the target. This information reveals that the amorphization is caused by the fast cooling of the liquid layer produced on the impact face, and the sputtering is caused by the evaporation of the melt. A collection of sensitivity analysis gauges how both phenomena are influenced by the silicon interaction potential, and the projectile's velocity, size, angle of incidence, dose, and composition. The projectile's velocity plays the most significant role. The thickness of the melt becomes comparable to the droplet's diameter at around 3 km/s, as reported by the experiments. Sputtering is first observed approximately at 3 km/s in agreement with the evaporation mechanism. The projectile's composition plays a major role. By using droplets with molecules of larger size and weight, the temperatures and sputtering near the impact interface increase considerably.

  9. 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.

  10. 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.

  11. DebrisLV Hypervelocity Impact Post-Shot Physical Results Summary

    DTIC Science & Technology

    2015-02-27

    has been extraordinarily fruitful in yielding new understanding of hypervelocity impacts. © The Aerospace Corporation 2015 DebrisLV...psia xenon in main tank; 50 psia helium in NCT titanium tank •  Tank mounted ~45° angle; projectile flying horizontally as shown (left

  12. 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.

  13. Measuring the Shape and Orientation of the Galactic Dark-Matter Halo using Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Gnedin, Oleg

    2009-07-01

    We propose to obtain high-resolution images of five hypervelocity stars in the Galactic halo in order to establish the first-epoch astrometric frame for them, as a part of a long-term program to measure precise proper motions. The origin of these recently discovered stars, all with positive radial velocities above 540 km/s, is consistent only with being ejected from the deep potential well of the massive black hole at the Galactic center. The deviations of their space motions from purely radial trajectories probe the departures from spherical symmetry of the Galactic potential, mainly due to the triaxiality of the dark-matter halo. Reconstructing the full three-dimensional space motion of the hypervelocity stars, through astrometric proper motions, provides a unique opportunity to measure the shape and orientation of the dark halo. The hypervelocity stars allow measurement of the potential up to 75 kpc from the center, independently of and at larger distances than are afforded by tidal streams of satellite galaxies such as the Sagittarius dSph galaxy. HVS3 may be associated with the LMC, rather then the Galactic center, and would therefore present a case for a supermassive black hole at the center of the LMC. We request one orbit with ACS/WFC for each of the five hypervelocity stars to establish their current positions relative to background galaxies. We will request a repeated observation of these stars in Cycle 17, which will conclusively measure the astrometric proper motions.

  14. Measuring the Shape and Orientation of the Galactic Dark-Matter Halo using Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Gnedin, Oleg

    2006-07-01

    We propose to obtain high-resolution images of five hypervelocity stars in the Galactic halo in order to establish the first-epoch astrometric frame for them, as a part of a long-term program to measure precise proper motions. The origin of these recently discovered stars, all with positive radial velocities above 540 km/s, is consistent only with being ejected from the deep potential well of the massive black hole at the Galactic center. The deviations of their space motions from purely radial trajectories probe the departures from spherical symmetry of the Galactic potential, mainly due to the triaxiality of the dark-matter halo. Reconstructing the full three-dimensional space motion of the hypervelocity stars, through astrometric proper motions, provides a unique opportunity to measure the shape and orientation of the dark halo. The hypervelocity stars allow measurement of the potential up to 75 kpc from the center, independently of and at larger distances than are afforded by tidal streams of satellite galaxies such as the Sagittarius dSph galaxy. HVS3 may be associated with the LMC, rather then the Galactic center, and would therefore present a case for a supermassive black hole at the center of the LMC. We request one orbit with ACS/WFC for each of the five hypervelocity stars to establish their current positions relative to background galaxies. We will request a repeated observation of these stars in Cycle 17, which will conclusively measure the astrometric proper motions.

  15. 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.

  16. Powder Extinguishants for Jet-Fuel Fires

    NASA Technical Reports Server (NTRS)

    Altman, R. L.; Mayer, L. A.; Ling, A. C.

    1986-01-01

    Mixtures of alkali metal dawsonite and metal halide show superior performance. In tests of new dry powder fire extinguishants, mixtures of potassium dawsonite with either stannous iodide or potassium iodide found effective for extinguishing jet-fuel fires on hot metal surfaces (up to 900 degrees C). Mixtures performed more effectively than either compound alone.

  17. NASA Jet Noise Research

    NASA Technical Reports Server (NTRS)

    Henderson, Brenda

    2016-01-01

    The presentation highlights NASA's jet noise research for 2016. Jet-noise modeling efforts, jet-surface interactions results, acoustic characteristics of multi-stream jets, and N+2 Supersonic Aircraft system studies are presented.

  18. [Jet lag].

    PubMed

    Lagarde, D; Doireau, P

    1997-01-01

    Desynchronization of circadian rhythmicity resulting from rapid travel through at least four time zones leads to symptoms known in everyday English as jet-lag. The most detrimental effect of jet-lag is fatigue with poor alertness and psychomotor performance. Severity is subject to individual variation in susceptibility (morning/evening typology, age,...) and environmental factors (direction of travel, number of time zones crossed, psychosocial environment...). Many measures used to prevent or reduce jet lag are inappropriate or ineffective and some may even be dangerous, such as use of melatonin. One of the most reliable preventive techniques consists of reinforcing social synchronizers by maintaining exposure to sunlight and social activity. Only two drugs currently available on the market can be recommended, i.e. non-benzodiazepinic hypnotics which induce high quality sleep to allow quick recovery and a new time-release caffeine agent which has been shown to prolong psychomotor performance.

  19. 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.

  20. Evaluation of Future Jet Fuel Combustion Characteristics

    DTIC Science & Technology

    1978-07-01

    content, fuel nitrogen, volatility, viscosity, olefinic content, sulfur , and trace metal content. hydrogen content in future crudes will be the most...processes would be expected. Both sulfur and trace metals are at very low concentrations in current jet fuels. Sulfur is typically less than 0.1% because...the petroleum fraction used for jet fuel production is nearly void of sulfur -containing compounds. Although syncrudes from coal or oil shale would be

  1. 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).

  2. First-Order Simulation of Strewn Debris Fields Accompanying Exoatmospheric Re-entry Vehicle Fragmentation by Hypervelocity Impact

    DTIC Science & Technology

    1994-09-01

    1961). 21. Passey, Quinn R., H.J. Melosh , Effects of Atmospheric Breakup on Crater Field Formation, Icarus 42, 211-253 (1980). 22. CRC Handbook...ORDER SIMULATION OF STREWN DEBRIS FIELDS ACCO:MPANYING EXOATMOSPHERIC RE-ENTRY VEillCLE FRAGMENTATION BY HYPERVELOCITY IMPACT by Dr. Gregory W...STREWN DEBRIS FIELDS ACCOMPANYING EXOATMOSPHERIC RE-ENTRY VEHICLE FRAGMENTATION BY HYPERVELOCITY IMPACT by Dr. Gregory W. Frank Recommended By

  3. Characterizing Hypervelocity Impact (HVI)-Induced Pitting Damage Using Active Guided Ultrasonic Waves: From Linear to Nonlinear

    PubMed Central

    Liu, Menglong; Wang, Kai; Lissenden, Cliff J.; Wang, Qiang; Zhang, Qingming; Long, Renrong; Su, Zhongqing; Cui, Fangsen

    2017-01-01

    Hypervelocity impact (HVI), ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region), a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation) are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation), which are proven to be more sensitive than their linear counterparts to small-scale damage, are explored to characterize HVI-induced pitting damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting damage, based on which linear and nonlinear damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting damage is characterized in images in terms of the probability of occurrence. PMID:28772908

  4. Gas Jets

    NASA Technical Reports Server (NTRS)

    Chaplygin, S.

    1944-01-01

    A brief summary of the contents of this paper is presented here. In part I the differential equations of the problem of a gas flow in two dimensions is derived and the particular integrals by which the problem on jets is solved are given. Use is made of the same independent variables as Molenbroek used, but it is found to be more suitable to consider other functions. The stream function and velocity potential corresponding to the problem are given in the form of series. The investigation on the convergence of these series in connection with certain properties of the functions entering them forms the subject of part II. In part III the problem of the outflow of a gas from an infinite vessel with plane walls is solved. In part IV the impact of a gas jet on a plate is considered and the limiting case where the jet expands to infinity changing into a gas flow is taken up in more detail. This also solved the equivalent problem of the resistance of a gaseous medium to the motion of a plate. Finally, in part V, an approximate method is presented that permits a simpler solution of the problem of jet flows in the case where the velocities of the gas (velocities of the particles in the gas) are not very large.

  5. Boundary-Layer Transition on a Slender Cone in Hypervelocity Flow with Real Gas Effects

    NASA Astrophysics Data System (ADS)

    Jewell, Joseph Stephen

    The laminar to turbulent transition process in boundary layer flows in thermochemical nonequilibrium at high enthalpy is measured and characterized. Experiments are performed in the T5 Hypervelocity Reflected Shock Tunnel at Caltech, using a 1 m length 5-degree half angle axisymmetric cone instrumented with 80 fast-response annular thermocouples, complemented by boundary layer stability computations using the STABL software suite. A new mixing tank is added to the shock tube fill apparatus for premixed freestream gas experiments, and a new cleaning procedure results in more consistent transition measurements. Transition location is nondimensionalized using a scaling with the boundary layer thickness, which is correlated with the acoustic properties of the boundary layer, and compared with parabolized stability equation (PSE) analysis. In these nondimensionalized terms, transition delay with increasing CO2 concentration is observed: tests in 100% and 50% CO2, by mass, transition up to 25% and 15% later, respectively, than air experiments. These results are consistent with previous work indicating that CO2 molecules at elevated temperatures absorb acoustic instabilities in the MHz range, which is the expected frequency of the Mack second-mode instability at these conditions, and also consistent with predictions from PSE analysis. A strong unit Reynolds number effect is observed, which is believed to arise from tunnel noise. NTr for air from 5.4 to 13.2 is computed, substantially higher than previously reported for noisy facilities. Time- and spatially-resolved heat transfer traces are used to track the propagation of turbulent spots, and convection rates at 90%, 76%, and 63% of the boundary layer edge velocity, respectively, are observed for the leading edge, centroid, and trailing edge of the spots. A model constructed with these spot propagation parameters is used to infer spot generation rates from measured transition onset to completion distance. Finally, a novel

  6. 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.

  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. 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.

  9. 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.

  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. Stochastic modeling of hypervelocity impacts in attitude propagation of space debris

    NASA Astrophysics Data System (ADS)

    Sagnières, Luc B. M.; Sharf, Inna

    2017-02-01

    Bombardment of orbital debris and micrometeoroids on active and inoperative satellites is becoming an increasing threat to space operations and has significant consequences on space missions. Concerns with orbital debris have led agencies to start developing debris removal missions and knowing a target's rotational parameters ahead of time is crucial to the eventual success of such a mission. A new method is proposed, enabling the inclusion of hypervelocity impacts into spacecraft attitude propagation models by considering the transfer of angular momentum from collisions as a stochastic jump process. Furthermore, the additional momentum transfer due to ejecta created during these hypervelocity impacts, an effect known as momentum enhancement, is considered. In order to assess the importance of collisions on attitude propagation, the developed model is applied to two pieces of space debris by using impact fluxes from ESA's Meteoroid and Space Debris Terrestrial Environment Reference (MASTER) model.

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

    DOE PAGES

    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

  14. 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.

  15. Jet lag.

    PubMed

    Herxheimer, Andrew

    2008-12-04

    Jet lag affects most air travellers crossing five or more time zones; it tends to be worse on eastward than on westward flights. We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions to prevent or minimise jet lag? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2008 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found five systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: hypnotics, melatonin, and lifestyle and environmental adaptations.

  16. Hypervelocity impact of mm-size plastic projectile on thin aluminum plate

    NASA Astrophysics Data System (ADS)

    Poniaev, S. A.; Kurakin, R. O.; Sedov, A. I.; Bobashev, S. V.; Zhukov, B. G.; Nechunaev, A. F.

    2017-06-01

    The experimental studies of the process of hypervelocity (up to 6 km/s) impact of a mm-size projectile on a thin aluminum plate is described. The numerical simulation of this process is presented. The data on the evolution, structure, and composition of the debris cloud formed as a result of the impact are reported. Basic specific features of the debris cloud formation are revealed.

  17. 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.

  18. 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.

  19. Experimental Demonstration of Plasma-Drag Acceleration of a Dust Cloud to Hypervelocities

    SciTech Connect

    Ticos, 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 {mu}m, 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.

  20. Hypervelocity Impact Analysis of International Space Station Whipple and Enhanced Stuffed Whipple Shields

    DTIC Science & Technology

    2004-12-01

    The International Space Station (ISS) must be able to withstand the hypervelocity impacts of micrometeoroids and orbital debris that strike its many... orbital debris and micrometeoroid environment. Based upon this environment, special multi-stage shields called Whipple and Enhanced Stuffed Whipple Shields...thesis is to provide the Department of Defense a background in satellite shield theory and design in order to improve protection against micrometeoroid and orbital debris impacts on future space-based national systems.

  1. Holographic and PLIF measurements of free-flight hypervelocity flows in the AEDC Range G facility

    NASA Astrophysics Data System (ADS)

    Havener, George; Smith, Michael S.

    1992-07-01

    A laser diagnostics approach to investigating hypervelocity flows is presented which is based on pulsed laser holography (PLH) and planar laser-induced fluorescence (PLIF). PLH is used to visualize projectiles and near-wake flow fields, and holographic interferometry provides optical phase maps that are reducible to flow density. PLIF is used to visualize the distribtion of nitric oxide and to quantify number densities in planes across the wake.

  2. 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

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

    NASA Astrophysics Data System (ADS)

    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 Hα 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 Å 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 ~ 104 - 105 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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)

  8. Data report of hypervelocity micro-particle impact light flash data and MOS impact detector output

    NASA Astrophysics Data System (ADS)

    Serna, Patrick J.

    1995-06-01

    A series of hypervelocity impact tests were conducted at the Max-Plank Institut fur Kernphysik, Heidelberg, Germany using the Institut's 2 MV Van De Graaff micro-particle accelerator. The purpose of this experimental effort was to collect impact flash data resulting from hypervelocity impact events. The results of these test experiments are to be correlated with actual waveforms obtained from on-orbit systems. Furthermore, these experimental results will supplement ongoing theoretical predictions being conducted within the Phillips Laboratory by the Space Kinetic Impact/Debris Branch (pLJWSCD). This report only describes the instrumentation configuration and presents data collected from light flash measurements and a MOS micro-particle impact detector. An analysis of the acquired light flash data is contained in a separate report authored by Allahdadi, Medina, Serna, and Long. Iron particles in the mass range of 1 x 10(exp -15) to 8 x 10(exp -18) kg were accelerated to velocities between 7 and 38 km/sec. Three targets were used for these impact test: spacecraft optical lens, spacecraft optical sunshade, and MOS spacecraft micro-particle impact detector. The hypervelocity particle impacted the lens and micro-particle impact detector targets normal to the target surface. The sunshade was impacted at a 25 degree angle measured from the particle direction of flight.

  9. Time-frequency Analysis for Acoustic Emission Signals of Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Liu, W. G.; Pang, B. J.; Zhang, W.; Sun, F.; Guan, G. S.

    The risk of collision of man-made orbital debris with spacecraft in near Earth orbits continues to increase A major of the space debris between 1mm and 10mm can t be well tracked in Earth orbits Damage from these un-tracked debris impacts is a serious hazard to aircraft and spacecraft These on-orbit collisions occur at velocities exceeding 10km s and at these velocities even very small particles can create significant damage The development of in-situ impact detecting system is indispensable for protecting the spacecraft from tragedy malfunction by the debris Acoustic Emission AE detecting technique has been recognized as an important technology for non-destructive detecting due to the AE signals offering a potentially useful additional means of non-invasively gathering concerning the state of spacecrafts Also Acoustic emission health monitoring is able to detect locate and assess impact damage when the spacecrafts is impacted by hypervelocity space debris and micrometeoroids This information can help operators and designers at the ground station take effective measures to maintain the function of spacecraft In this article Acoustic emission AE is used for characterization and location for hypervelocity Impacts Two different Acoustic Emission AE sensors were used to detect the arrival time and signals of the hits Hypervelocity Impacts were generated with a two-stage light-gas gun firing small Aluminum ball projectiles 4mm 6 4mm In the impact studies the signals were recorded with Disp AEwin PAC instruments by the conventional crossing

  10. Test study on the performance of shielding configuration with stuffed layer under hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Ke, Fa-wei; Huang, Jie; Wen, Xue-zhong; Ma, Zhao-xia; Liu, Sen

    2016-10-01

    In order to study the cracking and intercepting mechanism of stuffed layer configuration on the debris cloud and to develop stuffed layer configuration with better performance, the hypervelocity impact tests on shielding configurations with stuffed layer were carried out. Firstly, the hypervelocity impact tests on the shielding configuration with stuffed layer of 3 layer ceramic fibre and 3 layer aramid fibre were finished, the study results showed that the debris cloud generated by the aluminum sphere impacting bumper at the velocity of about 6.2 km/s would be racked and intercepted by the stuffed layer configuration efficiently when the ceramic fibre layers and aramid fibre layers were jointed together, however, the shielding performance would be declined when the ceramic fibre layers and aramid fibre layers were divided by some distance. The mechanism of stuffed layer racking and intercepting the debris cloud was analyzed according to the above test results. Secondly, based on the mechanism of the stuffed layer cracking and intercepint debirs cloud the hypervelocity impact tests on the following three stuffed layer structures with the equivalent areal density to the 1 mm-thick aluminum plate were also carried out to compare their performance of cracking and intercepting debris cloud. The mechanisms of stuffed layer racking and intercepting the debris cloud were validated by the test result. Thirdly, the influence of the stuffed layer position on the shielding performance was studied by the test, too. The test results would provide reference for the design of better performance shielding configuration with stuffed layer.

  11. Detection of hypervelocity impact radio frequency pulses through prior constrained source separation

    NASA Astrophysics Data System (ADS)

    Nuttall, Andrew; Kochenderfer, Mykel; Close, Sigrid

    2016-10-01

    Hypervelocity dust impacts produce electromagnetic pulses in the radio frequency (RF) spectrum that scales with impactor mass and velocity. Due to the mass acceleration limitations of ground-based facilities, detecting emissions from impacts in a laboratory setup is difficult due to their low output power. This paper presents a general probabilistic technique to perform signal excision, which was applied to synthetic and hypervelocity impact data sets. The task of excising multiple signals from a single observation of their mixtures is referred to as underdetermined blind source separation (BSS). This paper introduces a framework for solving underdetermined BSS problems when there is only one observation signal by leveraging often overlooked prior information. The most probable solutions for the source signals are computed by solving an iterative constrained optimization problem that seeks to maximize the posterior probability of the system model. In the hypervelocity impact data set, the goal was to reduce the noise floor on an RF antenna by modeling and extracting exterior sources of noise. It was found that the algorithm described in this paper was able to model signals in the observation and subtract them while still maintaining the spectral and temporal content of the remaining signals. Through the use of this methodology, previously hidden impact emissions were able to be isolated and identified for further characterization.

  12. Nuclear composition of magnetized gamma-ray burst jets

    NASA Astrophysics Data System (ADS)

    Shibata, Sanshiro; Tominaga, Nozomu

    2015-06-01

    We investigate the fraction of metal nuclei in the relativistic jets of gamma-ray bursts associated with core-collapse supernovae. We simulate the fallback in jet-induced explosions with two-dimensional relativistic hydrodynamics calculations and the jet acceleration with steady, radial, relativistic magnetohydrodynamics calculations, and derive the detailed nuclear composition of the jet by post-processing calculation. We found that if the temperature at the jet launch site is above 4.7 × 109 K, quasi-statistical equilibrium is established and heavy nuclei are dissociated into light particles such as 4He during the acceleration of the jets. The criterion for the survival of metal nuclei is written in terms of the isotropic jet luminosity as L_j^iso ≲ 3.9 × 10^{50} ( R_i/107 cm)^2(1 + σi) erg s-1, where Ri and σi are the initial radius of the jets and the initial magnetization parameter, respectively. If the jet is initially dominated by radiation field (i.e., σi ≪ 1) and the isotropic luminosity is relatively high (L_j^iso ≳ 4 × 10^{52} erg s-1), the metal nuclei cannot survive in the jet. On the other hand, if the jet is mainly accelerated by magnetic field (i.e., σi ≫ 1), metal nuclei initially contained in the jet can survive without serious dissociation even in the case of a high-luminosity jet. If the jet contains metal nuclei, the dominant nuclei are 28Si, 16O, and 32S and the mean mass number can be ˜ 25.

  13. 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.

  14. 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

  15. 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

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

    2015-04-01

    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). 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. 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. 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.

  16. Jet lag

    PubMed Central

    2008-01-01

    Introduction Jet lag is a syndrome caused by disruption of the "body clock", and affects most air travellers crossing five or more time zones; it tends to be worse on eastward than on westward flights. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical question: What are the effects of interventions to prevent or minimise jet lag? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2008 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found five systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: hypnotics, lifestyle and environmental adaptations, and melatonin. PMID:19445780

  17. 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.

  18. 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.

  19. 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.

  20. Probing Runaway Electrons with Nanoparticle Plasma Jet

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    The injection of C60/C nanoparticle plasma jet (NPPJ) into tokamak plasma during a major disruption has the potential to probe the runaway electrons (REs) during different phases of their dynamics and diagnose them through spectroscopy of C ions visible/UV lines. A C60/C NPPJ of ~75 mg, high-density (>1023 m-3), hyper-velocity (>4 km/s), and uniquely fast response-to-delivery time (~1 ms) has been demonstrated on a test bed. It can rapidly and deeply deliver enough mass to increase electron density to ~2.4 × 1021 m-3, ~60 times larger than typical DIII-D pre-disruption value. We will present the results of our investigations on: 1) C60 fragmentation and gradual release of C atoms along C60 NPPJ penetration path through the RE carrying residual cold plasma, 2) estimation of photon emissivity coefficient for the lines of the C ions, and 3) simulation of C60/C PJ penetration to the RE beam location in equivalent conditions to the characteristic ~1 T B-field of DIII-D. The capabilities of this injection technique provide a unique possibility in understanding and controlling the RE beam, which is a critical problem for ITER. Work supported by US DOE DE-SC0011864 Grant.

  1. 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.

  2. 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.

  3. Hydro-Jet technology in urologic surgery.

    PubMed

    Shekarriz, Bijan

    2005-05-01

    Hydro-Jet technology utilizes an extremely thin, high-pressure stream of water. This technology has been routinely used in industry as a cutting tool for different materials such as metal, ceramic, wood and glass. Recently, Hydro-Jet technology has been used for dissection and resection during open and laparoscopic surgical procedures. A high-pressure jet of water allows selective dissection and isolation of vital structures such as blood vessels and nerves. This has resulted in improved dissection and decreased complication rate in recent experimental and clinical studies. This technology has been successfully applied during open and laparoscopic partial nephrectomy, cholecystecomy and retroperitoneal lymphadenectomy.

  4. Hyper-velocity impact risk assessment and mitigation strategies in the context of future X-ray astronomy missions

    NASA Astrophysics Data System (ADS)

    Perinati, Emanuele; Rott, Martin; Santangelo, Andrea; Tenzer, Chris

    2017-06-01

    Future X-ray astronomy missions will be based on instruments with apertures much larger than those used up to now. Therefore, the risk posed by hyper-velocity dust grains in the space environment to the onboard instrumentation will increase, especially when a larger aperture is combined with a longer focal length. Starting from the lessons learned from the XMM and Swift satellites, we review the question of hyper-velocity impacts and discuss the expected impact-rate, risk of damage and possible mitigation strategies in the context of LOFT, eROSITA and ATHENA.

  5. 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.

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

    PubMed

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

    2008-04-01

    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.

  7. The hypervelocity impact facilities at the University of Kent at Canterbury, UK

    NASA Technical Reports Server (NTRS)

    Burchell, Mark J.; Mcdonnell, J. A. M.; Cole, M. J.; Ratcliff, P. R.

    1994-01-01

    The University of Kent at Canterbury facilities for production of hypervelocity impacts are discussed. Meteoroids are simulated by electrostatic acceleration of small (10(exp -12) - 10(exp -17) kg) particles using a 2-MV Van de Graaff accelerator. This machine has been operational for many years; both the machine and experimental area are currently being upgraded. Larger particles (10(exp -10) - 10(exp -14) kg) are accelerated using a more recently installed light gas gun. The status of all hardware (including experimental areas) is given, along with brief details of recent, current, and future projects making use of them.

  8. 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.

  9. Infrared surface temperature measurements in NAVSWC's Hypervelocity Wind Tunnel No. 9

    NASA Astrophysics Data System (ADS)

    Lafferty, John F.; Collier, Arnold S.

    The authors describe recent efforts at the U.S. Naval Surface Warfare Center's Hypervelocity Wind Tunnel No. 9 to measure wind tunnel model surface temperatures using a commercially available infrared (IR) camera. IR camera measurements on a Macor model surface tested at Mach 14 in Tunnel 9 are presented, and the data are compared to vapor-deposited thermocouple measurements made on the same substrate. The IR data were collected using an Inframetrics Model 600 infrared camera and were reduced using the camera manufacturer's software. The results of this analysis show the feasibility of making global nonintrusive heat transfer measurements using an infrared camera.

  10. 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

  11. The Production of Contamination on Spacecraft Surfaces by Hypervelocity Debris Impacts

    DTIC Science & Technology

    2000-10-01

    temperatures in the range of 5,000K and pressures of 7.5km/sec and other components of the several megabars when they strike a surface. Low Earth ...glass can be increased so that they can withstand the rigors of ground handling and launch and Spacecraft placed in low- Earth orbit (LEO) are deployment...stresses. exposed to a large flux of hypervelocity impacts by small particles which originate from micro- meteorites and man generated debris"𔃼’ 3. At

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    SciTech Connect

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

    2016-07-15

    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.

  10. 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.

  11. 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.

  12. Hypervelocity impact testing above 10 km/s of advanced orbital debris shields

    SciTech Connect

    Christiansen, E.L.; Crews, J.L.; Kerr, J.H.; Chhabildas, L.C.

    1996-05-01

    NASA has developed enhanced performance shields to improve the protection of spacecraft from orbital debris and meteoroid impacts. One of these enhanced shields includes a blanket of Nextel{trademark} ceramic fabric and Kevlar{trademark} high strength fabric that is positioned midway between an aluminum bumper and the spacecraft pressure wall. As part of the evaluation of this new shielding technology, impact data above 10 km/sec has been obtained by NASA Johnson Space Center (JSC) from the Sandia National Laboratories HVL ({open_quotes}hypervelocity launcher{close_quotes}) and the Southwest Research Institute inhibited shaped charge launcher (ISCL). The HVL launches flyer-plates in the velocity range of 10 to 15 km/s while the ISCL launches hollow cylinders at {approximately}11.5km/s. The {gt}10km/s experiments are complemented by hydrocode analysis and light-gas gun testing at the JSC Hypervelocity Impact Test Facility (HIT-F) to assess the effects of projectile shape on shield performance. Results from the testing and analysis indicate that the Nextel{trademark}/Kevlar{trademark} shield provides superior protection performance compared to an all-aluminum shield alternative. {copyright} {ital 1996 American Institute of Physics.}

  13. 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.

  14. The hypervelocity hot subdwarf US 708 - remnant of a double-detonation SN Ia?

    NASA Astrophysics Data System (ADS)

    Geier, Stephan

    2013-10-01

    Type Ia supernovae {SN Ia} are the most important standard candles for measuring the expansion history of the universe. The thermonuclear explosion of a white dwarf can explain their observed properties, but neither the progenitor systems nor any stellar remnants have been conclusively identified. Underluminous SN Ia have been proposed to originate from a so-called double-detonation of a white dwarf. After a critical amount of helium is deposited on the surface through accretion from a close companion, the helium is ignited causing a detonation wave that triggers the explosion of the white dwarf itself. The helium star will then be ejected at so large a velocity that it will escape the Galaxy. The predicted properties of this remnant are an excellent match to the so-called hypervelocity star US 708, a hot, helium-rich star moving at more than 750 km/s, sufficient to leave the Galaxy.Here we propose medium-resolution COS spectroscopy to measure the vsini of the hypervelocity He-sdO US 708 for the first time and to search for abundance anomalies caused by pollution through an SN Ia event. This will allow us to test the double-detonation scenario with sdB donor empirically.

  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.

  16. 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.

  17. Projectile-target mixing in melted ejecta formed during a hypervelocity impact cratering event

    NASA Technical Reports Server (NTRS)

    Evans, Noreen Joyce; Ahrens, Thomas J.; Shahinpoor, M.; Anderson, W. W.

    1993-01-01

    Tektites contain little to no projectile contamination while, in contrast, some distal ejecta deposits can be relatively projectile-rich (e.g. the Cretaceous-Tertiary (K-T) boundary clay). This compositional difference motivated an experimental study of hypervelocity target-projectile mixing processes. We hope to scale up the results from these experiments and apply them to terrestrial impact structures like the Chicxulub Crater, Yucutan, Mexico, the leading contender as the site for the impact that caused the mass extinction that marks the K-T boundary. Shock decomposition of the approximately 500m thickness of anhydrite, or greater thickness of limestone, in the target rocks at Chicxulub may have been a critical mechanism for either global cooling via SO3, and subsequently H2SO4, formation, or possibly, global warming via increased CO2 formation. Understanding target-projectile mixing processes during hypervelocity impact may permit more accurate estimates of the amount of potentially toxic, target-derived material reaching stratospheric heights.

  18. 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.

  19. Bacillus subtilis spores on artificial meteorites survive hypervelocity atmospheric entry: implications for Lithopanspermia.

    PubMed

    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 degrees 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.

  20. Hypervelocity impact testing above 10 km/s of advanced orbital debris shields

    NASA Astrophysics Data System (ADS)

    Christiansen, Eric L.; Crews, Jeanne Lee; Kerr, Justin H.; Chhabildas, Lalit C.

    1996-05-01

    NASA has developed enhanced performance shields to improve the protection of spacecraft from orbital debris and meteoroid impacts. One of these enhanced shields includes a blanket of Nextel™ ceramic fabric and Kevlar™ high strength fabric that is positioned midway between an aluminum bumper and the spacecraft pressure wall. As part of the evaluation of this new shielding technology, impact data above 10 km/sec has been obtained by NASA Johnson Space Center (JSC) from the Sandia National Laboratories HVL ("hypervelocity launcher") and the Southwest Research Institute inhibited shaped charge launcher (ISCL). The HVL launches flyer-plates in the velocity range of 10 to 15 km/s while the ISCL launches hollow cylinders at ˜11.5 km/s. The >10 km/s experiments are complemented by hydrocode analysis and light-gas gun testing at the JSC Hypervelocity Impact Test Facility (HIT-F) to assess the effects of projectile shape on shield performance. Results from the testing and analysis indicate that the Nextel™/Kevlar™ shield provides superior protection performance compared to an all-aluminum shield alternative.

  1. 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.

  2. Control of jet noise

    NASA Technical Reports Server (NTRS)

    Schreck, Stefan

    1992-01-01

    To investigate the possibility of active control of jet noise, knowledge of the noise generation mechanisms in natural jets is essential. Once these mechanisms are determined, active control can be used to manipulate the noise production processes. We investigated the evolution of the flow fields and the acoustic fields of rectangular and circular jets. A predominant flapping mode was found in the supersonic rectangular jets. We hope to increase the spreading of supersonic jets by active control of the flapping mode found in rectangular supersonic jets.

  3. Understanding jet noise.

    PubMed

    Karabasov, S A

    2010-08-13

    Jets are one of the most fascinating topics in fluid mechanics. For aeronautics, turbulent jet-noise modelling is particularly challenging, not only because of the poor understanding of high Reynolds number turbulence, but also because of the extremely low acoustic efficiency of high-speed jets. Turbulent jet-noise models starting from the classical Lighthill acoustic analogy to state-of-the art models were considered. No attempt was made to present any complete overview of jet-noise theories. Instead, the aim was to emphasize the importance of sound generation and mean-flow propagation effects, as well as their interference, for the understanding and prediction of jet noise.

  4. Control of jet noise

    NASA Technical Reports Server (NTRS)

    Schreck, Stefan

    1993-01-01

    This reports describes experiments conducted at the High-Speed Jet Facility at the University of Southern California on supersonic jets. The goal of the study was to develop methods for controlling the noise emitted from supersonic jets by passive and/or active means. Work by Seiner et al (1991) indicates that eddy Mach wave radiation is the dominant noise source in a heated high speed jet. Eddy Mach radiation is caused by turbulent eddies traveling at supersonic speed in the shear layer of the jet. The convection velocity of the eddies decays with increasing distance from the nozzle exit due to the mixing of the jet stream with the ambient fluid. Once the convection speed reaches subsonic velocities, eddy Mach wave radiation ceases. To control noise, a rapid decay of the convection velocity is desired. This may be accomplished by enhanced mixing in the jet. In this study, small aspect ratio rectangular jet nozzles were tested. A flapping mode was noticed in the jets. By amplifying screech components of the jets and destabilizing the jet columns with a collar device, the flapping mode was excited. The result was a rapid decay of the jet velocity. A reduction in eddy Mach radiation in rectangular supersonic jets may be achieved with this device.

  5. 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

  6. Glottal jet inertance

    NASA Astrophysics Data System (ADS)

    Mphail, Michael; Krane, Michael

    2016-11-01

    Estimates of an inertive contribution of the glottal jet to glottal aerodynamic resistance is presented. Given that inertance of the flow in a constriction can be expressed in terms of the kinetic energy of the flow, and that a jet is a maximum kinetic energy flow pattern, it is argued that the glottal jet possesses its own inertance which is at least as large as that of the vocal tract. These arguments are supported by estimates of inertance obtained from simulations of an unsteady flow through an axisymmetric orifice, and of a compliant constriction with the approximate shape and mechanical properties of the vocal folds. It is further shown that the inertive effect of the glottal jet depends on the jet path and jet mixing, with a slowly diffusing, symmetric jet showing higher inertance than an asymmetric jet which rapidly mixes with supraglottal air. Acknowledge support of NIH Grant 2R01DC005642-10A1.

  7. Fountain-Jet Turbulence.

    DTIC Science & Technology

    1980-09-01

    and 3 times higher than expected from free- jet results. Hill et al., (Reference 6) in work with foun- tain jets impacting fuselage models, detected ...delineate the origins of the turbulent anomalies associated with fountain jets by extending the previous studies. The results are presented herein...jet velocities were detected with a Thermal Systems Inc. Model 1050 dual-channel constant-temperature anemometer equipped with a Thermal Systems Inc

  8. 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.

  9. 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.

  10. 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

  11. Fluorescent aerogels for the capture and identification of hypervelocity extraterrestrial particles

    NASA Astrophysics Data System (ADS)

    Dominguez, Gerardo

    Contemporary interstellar dust has never been analyzed in the laboratory, despite its obvious astronomical importance and its potential as a probe of stellar nucleosynthesis and galactic chemical evolution. Aerogels are ultra-low-density solids that are capable of capturing hypervelocity ( v > 1 km s -1 ) micrometeorites while minimizing their vaporization. Large aerogel collectors have previously been deployed in low- Earth orbit. Given their large exposure times, these aerogel collectors, which are made out of SiO 2 , should have captured large numbers of extraterrestrial (interstellar and interplanetary) dust grains. However, conventional aerogels lack the capacity of reconstructing the impact velocity of captured hypervelocity projectiles. I have developed a model that relates the energy loss of captured projectiles to the formation of impact tracks in aerogels. This model explains why the physical dimensions of impact tracks in aerogels are only weakly dependent on the velocity of the captured projectile. I have also discovered that the rapid and local deposition of heat that results from the capture of mm-sized hypervelocity projectiles can produce fluorescent impact tracks in Al 2 O 3 , SiO 2 , and Al 2 O 3 -SiO 2 aerogels that are synthesized with certain dopants. In addition, I have shown that the integrated brightness of UV-induced fluorescence is a function of the size and velocity of the projectile. I have discovered several matrix-dopant systems capable of producing fluorescent impact tracks. I have done detailed measurements of the response function and the velocity resolution of a (Gd,Tb)-doped SiO 2 aerogel. The form of the response function suggests that these calorimetric aerogels respond to the kinetic energy loss of captured projectiles. I have shown that this aerogel is sensitive to interstellar dust analogues consisting of sub- micron (0.75 mm) and micron-sized latex spheres (1.6 mm) with impact velocities up to 22 km s -1 . Because a large

  12. 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.

  13. Anode jet in a high-current vacuum arc

    NASA Astrophysics Data System (ADS)

    Popov, S. A.; Schneider, A. V.; Batrakov, A. V.; Sandolache, G.; Rowe, S. W.; Markov, A. B.; Zyul'kova, L. A.

    2012-07-01

    A stable intense jet with a clear-cut bright sheath has been detected on the anode of a 10-ms-long high-current vacuum arc with a current amplitude of 15 kA. The jet is adjacent to the hot spot of a molten metal on the anode surface. The primary light of the jet is emitted by neutrals. The sheath of the jet is surrounded by an ion-induced diffuse glow. The anode jet arises from interaction between the cathode and anode plasmas. Because of this, the size of the jet inversely depends on the current of the arc and the jet becomes observable only by the end of the current pulse. This object (anode jet with a bright sheath) is well reproducible when the arc is initiated between copper-chromium electrodes. In the case of pure copper electrodes, such objects occur randomly and appear at long projections of the molten metal, where heat release is hampered, and at large drops moving in the interelectrode gap. This means that the anode evaporation intensity is crucial for the appearance of bright-sheath jets.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Particle-in-cell simulations of an RF emission mechanism associated with hypervelocity impact plasmas

    NASA Astrophysics Data System (ADS)

    Fletcher, Alex C.; Close, Sigrid

    2017-05-01

    Radio frequency (RF) emission from hypervelocity impacts has been detected in multiple experiments, but the physical mechanism responsible is not well understood. Plasma is created by these impacts and rapidly expands into the surrounding vacuum; it's been argued that the observed RF emission is associated with a process in the plasma. A recent model proposes that coherent oscillations from a large scale charge separation due to the expansion of the plasma can produce RF. In this paper, we use a discontinuous Galerkin particle-in-cell technique to simulate this process. Initial conditions are drawn from hydrocode impact simulations, and the results are compared to experimental measurements. Under the assumption that there exists a difference in bulk speed of electrons and ions at a certain point in the expansion, we do find that radiation is produced by the plasma.

  19. 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).

  20. 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.

  1. 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.

  2. Interpolation/extrapolation technique with application to hypervelocity impact of space debris

    NASA Technical Reports Server (NTRS)

    Rule, William K.

    1992-01-01

    A new technique for the interpolation/extrapolation of engineering data is described. The technique easily allows for the incorporation of additional independent variables, and the most suitable data in the data base is automatically used for each prediction. The technique provides diagnostics for assessing the reliability of the prediction. Two sets of predictions made for known 5-degree-of-freedom, 15-parameter functions using the new technique produced an average coefficient of determination of 0.949. Here, the technique is applied to the prediction of damage to the Space Station from hypervelocity impact of space debris. A new set of impact data is presented for this purpose. Reasonable predictions for bumper damage were obtained, but predictions of pressure wall and multilayer insulation damage were poor.

  3. 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.

  4. Heat Transfer Testing in the NSWC Hypervelocity Wind Tunnel Utilizing Co-Axial Surface Thermocouples

    DTIC Science & Technology

    1980-03-19

    8217 DT L FILE COPY I NSWC MP 80-151 AD- A225 273 HEAT TRANSFER TESTING IN THE NSWC HYPERVELOCITY WIND TUNNEL UTILIZING I CO-AXIAL SURFACE...ui - z Ur) 2 MIT- UA U*) C> In> (NJ 01 0017 20 U NSWC MP 80-151 Iz It c 06I- U) zII 00a Lii Vl 0 1 2 - cr > zI 0 z U-- 01 OT ’O _ _ _~i 01 01 NSWC MP...CS.LN’X -- - - - -jJ -f- - - - Z r- - - ~ ~ - -- 4 I ------ ----- ----- ----------------------------------- V n A j) r A r% Cr r, -r n rO A r. A A C

  5. 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.

  6. 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.

  7. Hypervelocity Impact Behaviour of CFRP-A1/HC Sandwich Panel: Finite-Element Studies

    NASA Astrophysics Data System (ADS)

    Phadnis, Vaibhav A.; Roy, Anish; Silberschmidt, Vadim V.

    2014-06-01

    The mechanical response of CFRP-Al/HC (carbon fibre- reinforced/epoxy composite face sheets with Al honeycomb core) sandwich panels to hyper-velocity impact ( 1 km/s) is studied using a finite-element model developed in ABAQUS/Explicit. The intraply damage of CFRP face sheets is analysed by the means of a user-defined material model (VUMAT) employing a combination of Hashin and Puck criteria and delamination is modelled using cohesive-zone elements. The damage of 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 of HC core.

  8. 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.

  9. Active removal of orbital debris by induced hypervelocity impact of injected dust grains

    NASA Astrophysics Data System (ADS)

    Ganguli, G.; Crabtree, C.; Velikovich, A.; Rudakov, L.; Chappie, S.

    2014-02-01

    Collisions of an active satellite with a small (1mm - cm) untrackable orbital debris can be mission ending. It has been recently established that we are at the tipping point for collisional cascade of larger objects to exponential growth of small orbital debris. This will make access to near-Earth space hazardous without first clearing the existing debris from this region. We present a concept for elimination of small debris by deploying micron scale dust to artificially enhance the drag on the debris. The key physics that makes this technique viable is the possibility of large momentum boost realized through hypervelocity dust/debris collision. By deploying high mass density micron scale dust in a narrow altitude band temporarily it is possible to artificially enhance drag on debris spread over a very large volume and force rapid reentry. The injected dust will also reenter the atmosphere leaving no permanent residue in space.

  10. Discovery of Two New Hypervelocity Stars from the LAMOST Spectroscopic Surveys

    NASA Astrophysics Data System (ADS)

    Huang, Y.; Liu, X.-W.; Zhang, H.-W.; Chen, B.-Q.; Xiang, M.-S.; Wang, C.; Yuan, H.-B.; Tian, Z.-J.; Li, Y.-B.; Wang, B.

    2017-09-01

    We report the discovery of two new unbound hypervelocity stars (HVSs) from the LAMOST spectroscopic surveys. They are, respectively, a B2V-type star of ∼7 M ⊙ with a Galactic rest-frame radial velocity of 502 km s‑1 at a Galactocentric radius of ∼21 kpc and a B7V-type star of ∼4 M ⊙ with a Galactic rest-frame radial velocity of 408 km s‑1 at a Galactocentric radius of ∼30 kpc. The origins of the two HVSs are not clear given their currently poorly measured proper motions. However, the future data releases of Gaia should provide proper motion measurements accurate enough to solve this problem. The ongoing LAMOST spectroscopic surveys are expected to yield more HVSs to form a statistical sample, providing vital constraints on understanding the nature of HVSs and their ejection mechanisms.

  11. Projectile shape and material effects in hypervelocity impact response of dual-wall structures

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Darzi, Kent

    1992-01-01

    All large spacecraft are susceptible to impacts by meteoroids and pieces of orbiting space debris. These impacts occur at extremely high speeds and can damage flight-critical systems, which can in turn lead to catastrophic failure of the spacecraft. A long-duration spacecraft developed for a mission into this environment must include adequate protection against perforation of pressurized components by such impacts. This paper presents the results of an investigation into the effects of projectile shape and material on the perforation of aluminum dual-wall structural systems. Impact damage is characterized according to the extent of perforation, crater, and spall damage in the structural systems as a result of hypervelocity projectile impact loadings. Analysis of the damage data shows that there are distinct differences in impact damage from cylindrical and spherical projectiles. Projectile density is also found to affect the type and extent of damage sustained by dual-wall structural systems.

  12. Mixing, ignition and combustion studies using discrete orifice injection at hypervelocity flight conditions

    NASA Technical Reports Server (NTRS)

    Bakos, R.; Tamagno, J.; Trucco, R.; Rizkalla, O.; Chinitz, W.

    1991-01-01

    Testing at hypervelocity test conditions continues in the Hypulse expansion tube. A newly-calibrated Mach 13 operating point has been achieved, and hydrogen injection studies were performed at this test condition. The experiments were conducted in a 2-in x 1-in combustor model employing three injector configurations: a single flush-wall circular orifice; two such orifices on opposite walls (the 'dual' injector configuration); and two orifices on the upper and the lower walls (the 'quad' injector configuration). The quad injectors were distinctly superior to the other two configurations in promoting mixing, ignition, and combustion. The single injector, however, proved to be superior to the dual injectors, supporting the concept that the aspect ratio of the 'injection cell' plays a large role in promoting the processes required to achieve high combustion efficiency.

  13. 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.

  14. 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.

  15. Simulation of Hypervelocity Impact Effects on Reinforced Carbon-Carbon. Chapter 6

    NASA Technical Reports Server (NTRS)

    Park, Young-Keun; Fahrenthold, Eric P.

    2004-01-01

    Spacecraft operating in low earth orbit face a significant orbital debris impact hazard. Of particular concern, in the case of the Space Shuttle, are impacts on critical components of the thermal protection system. Recent research has formulated a new material model of reinforced carbon-carbon, for use in the analysis of hypervelocity impact effects on the Space Shuttle wing leading edge. The material model has been validated in simulations of published impact experiments and applied to model orbital debris impacts at velocities beyond the range of current experimental methods. The results suggest that momentum scaling may be used to extrapolate the available experimental data base, in order to predict the size of wing leading edge perforations at impact velocities as high as 13 km/s.

  16. 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.

  17. 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.

  18. 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.

  19. Necessary conditions for maximax problems with application to aeroglide of hypervelocity vehicles

    NASA Technical Reports Server (NTRS)

    Vinh, N. X.; Lu, P.

    1986-01-01

    This paper presents the necessary conditions for solving Chebyshev minimax (or maximax) problems with bounded control. The jump conditions obtained are applicable to problems with single or multiple maxima. By using Contensou domain of maneuverability, it is shown that when the maxima are isolated single points the control is generally continuous at the jump point in the minimax problems and discontinuous in the maximax problems in which the first time derivative of the maximax function contains the control variable. The theory is applied to the problem of maximizing the flight radius in a closed circuit glide of a hypervelocity vehicle and to a maximax optimal control problem in which the control appears explicitly with the first time derivative of the maximax function.

  20. Determining the Onset of Amorphization of Crystalline Silicon due to Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Poletti, C. Shane; Bachlechner, Martina E.

    2009-03-01

    Atomistic simulations were performed to study a hypervelocity impactor striking a silicon/silicon nitride interface with varying silicon substrate thicknesses. Visualization indicates that the crystalline silicon amorphizes upon impact. The objective of the present study is to determine where the boundary between amorphous and crystalline silicon occurrs. In the analysis, the silicon substrate is separated into sixty layers and for each layer the average z displacement is determined. Our results show that the boundary between amorphous and crystalline silicon occurs between layers 20 and 22 for an impactor traveling at 5 km/s. This corresponds to a depth of approximately 32 Angstroms into the silicon. More detailed analyses reveals that the z displacement is noticeably larger for the layers that do not have a silicon atom bonded beneath them compared to the ones that do.

  1. Target selection for a hypervelocity asteroid intercept vehicle flight validation mission

    NASA Astrophysics Data System (ADS)

    Wagner, Sam; Wie, Bong; Barbee, Brent W.

    2015-02-01

    Asteroids and comets have collided with the Earth in the past and will do so again in the future. Throughout Earth's history these collisions have played a significant role in shaping Earth's biological and geological histories. The planetary defense community has been examining a variety of options for mitigating the impact threat of asteroids and comets that approach or cross Earth's orbit, known as near-Earth objects (NEOs). This paper discusses the preliminary study results of selecting small (100-m class) NEO targets and mission analysis and design trade-offs for validating the effectiveness of a Hypervelocity Asteroid Intercept Vehicle (HAIV) concept, currently being investigated for a NIAC (NASA Advanced Innovative Concepts) Phase 2 study. In particular this paper will focus on the mission analysis and design for single spacecraft direct impact trajectories, as well as several mission types that enable a secondary rendezvous spacecraft to observe the HAIV impact and evaluate it's effectiveness.

  2. 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.

  3. Thermal visualization of heat-transfer characteristics for single impinging jet

    NASA Astrophysics Data System (ADS)

    Li, Liguo; Zhu, Yun; Zhang, Jingzhou; Yu, Wei

    The local heat-transfer characteristics of an impingement-cooling jet are presently ascertained, for cases with and without crossflow, through the use of a combined metal heating-element and cholesteric liquid crystal system. The results obtained indicate that the impingement Nusselt numbers of double-peak values increase with rising jet Reynolds number. A moving cylindrical jet-source model is used to simulate and analyze the jet's impingement heat transfer.

  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. Large bouncing jets

    NASA Astrophysics Data System (ADS)

    Cardin, Karl; Weislogel, Mark

    2016-11-01

    We experimentally investigate the phenomena of large jet rebound (bounce), a mode of fluid transfer following oblique jet impacts on hydrophobic surfaces. We initially seek to describe the regimes of such jet bounce in tests conducted in the weightless environment of a drop tower. A parametric study reveals the dependence of the rebound mode on the relevant dimensionless groups such as Weber number We⊥ defined on the velocity component perpendicular to the surface. We show that significantly larger diameter jets behave similarly as much smaller jets demonstrated during previous terrestrial investigations when We⊥ 1 . For We⊥ > 1 , large jet impacts create fishbone-like structures. We also explore rebounds from nonplanar substrates. Improving our understanding of such jet rebound opens avenues for unique transport capabilities. NASA Cooperative Agreement NNX12A047A.

  6. Hydroacoustic pulsating jet generator

    NASA Astrophysics Data System (ADS)

    Unrau, A.; Meier, G. E. A.

    1987-04-01

    A high pressure turbulent jet generator connected to a low pressure hydraulic tube is studied to investigate water hammer in tubes with fast flow variations, generating high pressure pulsating water jets. The pulsating jet generator consists of a tube, a hydraulic valve, a spring, and a water container. The jet is the effect of the combination of turbulent pipe flow with a valve for flow nozzle. The jet pressure depends on specific oscillation impedance and flow velocity variations. For inlet pressure of 0.5 to 2 bar the pressure rises to 40 bar. The described pulsating jet generator is more effective than the earlier model. A piezoelectric pressure controller is used to register pressure signals and high speed photos are made of the jet. Test results are consistent with theoretical calculation.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Determination of parameters for hypervelocity dust grains encountered in near-Earth space

    NASA Technical Reports Server (NTRS)

    Tanner, William G.; Maag, Carl R.; Alexander, W. Merle; Sappenfield, Patricia

    1993-01-01

    Primarily interest was in the determination of the population of micrometeoroids and space debris and interpretation of the hole size in a thin film or in a micropore foam returned from space with theoretical calculations describing the event. In order to augment the significance of the theoretical calculations of the impact event, an experiment designed to analyze the charge production due to hypervelocity impacts on thin films also produced data which described the penetration properties of micron and sub-micron sized projectiles. The thin film penetration sites in the 500 A and 1000 A aluminum films were counted and a size distribution function was derived. In the case of the very smallest dust grains, there were no independent measurements of velocities like that which existed for the larger dust grains (d(sub p) is less than or equal to 1 micron). The primary task then became to assess the relationship between the penetration hole and the particle diameter of the projectile which made the hole. The most promising means to assess the measure of the diameters of impacting grains came in the form of comparing cratering mechanics to penetration mechanics. Future experimentation will produce measurements of the cratering as opposed to the penetrating event. Particles encountered by surfaces while being flown in space will degrade that surface in a systematic manner even when the impact is with small hypervelocity particles, d(sub p) is less than or equal to 10 microns. Though not to a degree which would precipitate a catastrophic failure of a system, the degradation of the materials comprising the interconnected system will occur. It is the degradation of the optical system and the subsequent embrittlement of other materials that can lead to degradation if not to failure. It is to this end that research was conducted to compare the primary consequences for experiments which will be flown to those which have been returned.

  13. 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

  14. Numerical Simulation of Major Debris-Cloud Features Produced by Projectile Hypervelocity Impact on Bumper

    NASA Astrophysics Data System (ADS)

    Ma, W. L.; Pang, B. J.; Zhang, W.; Gai, B. Z.

    All spacecrafts in low orbit are subjected to hypervelocity impacting by meteoroids and space debris These impacts can damage spacecraft flight-critical systems leading to catastrophic failure of the spacecraft In order to protect the safety of an orbiting spacecraft the shield for meteoroids and space debris becomes an indispensable factor in the design of a spacecraft especially those with long orbital life and large size structures Because the major debris-cloud represents the most severe threat to rear wall integrity researches on the major debris-cloud features are very important In this paper the numerical simulations for major debris-cloud features produced by a sphere projectile normal impacting on a single-sheet bumper at hypervelocity have been carried out using the SPH technique of AUTODYN The major debris-cloud features include the effects of debris-cloud morphology normalized axial velocity and radial velocity These features vary with bumper-thickness-to-projectile-diameter ratios t D and impact velocities The impact velocities are from 1 to 14km s The bumper and projectile materials are aluminum The ratio t d is from 0 0105 to 0 525 Effects of impact velocity and t d on the major debris-cloud features have been investigated It is shown that the major debris-cloud features have remarkable differences with various t d and impact velocities As the t D ratio is increased and impact velocity is constant the major debris-cloud morphology varies The diameter of center element and the radial debris-cloud velocities increases At the same time

  15. New Hypervelocity Terminal Intercept Guidance Systems for Deecting/Disrupting Hazardous Asteroids

    NASA Astrophysics Data System (ADS)

    Lyzhoft, Joshua Richard

    Computational modeling and simulations of visual and infrared (IR) sensors are investigated for a new hypervelocity terminal guidance system of intercepting small asteroids (50 to 150 meters in diameter). Computational software tools for signal-to-noise ratio estimation of visual and IR sensors, estimation of minimum and maximum ranges of target detection, and GPU (Graphics Processing Units)-accelerated simulations of the IR-based terminal intercept guidance systems are developed. Scaled polyhedron models of known objects, such as the Rosetta mission's Comet 67P/C-G, NASA's OSIRIS-REx Bennu, and asteroid 433 Eros, are utilized in developing a GPU-based simulation tool for the IR-based terminal intercept guidance systems. A parallelized-ray tracing algorithm for simulating realistic surface-to-surface shadowing of irregular-shaped asteroids or comets is developed. Polyhedron solid-angle approximation is also considered. Using these computational models, digital image processing is investigated to determine single or multiple impact locations to assess the technical feasibility of new planetary defense mission concepts of utilizing a Hypervelocity Asteroid Intercept Vehicle (HAIV) or a Multiple Kinetic-energy Interceptor Vehicle (MKIV). Study results indicate that the IR-based guidance system outperforms the visual-based system in asteroid detection and tracking. When using an IR sensor, predicting impact locations from filtered images resulted in less jittery spacecraft control accelerations than conducting missions with a visual sensor. Infrared sensors have also the possibility to detect asteroids at greater distances, and if properly used, can aid in terminal phase guidance for proper impact location determination for the MKIV system. Emerging new topics of the Minimum Orbit Intersection Distance (MOID) estimation and the Full-Two-Body Problem (F2BP) formulation are also investigated to assess a potential near-Earth object collision risk and the proximity gravity

  16. 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.

  17. 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.

  18. 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.

  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. The jet in crossflowa)

    NASA Astrophysics Data System (ADS)

    Karagozian, Ann R.

    2014-10-01

    The jet in crossflow, or transverse jet, is a flowfield that has relevance to a wide range of energy and propulsion systems. Over the years, our group's studies on this canonical flowfield have focused on the dynamics of the vorticity associated with equidensity and variable density jets in crossflow, including the stability characteristics of the jet's upstream shear layer, as a means of explaining jet response to altered types of excitation. The jet's upstream shear layer is demonstrated to exhibit convectively unstable behavior at high jet-to-crossflow momentum flux ratios, transitioning to absolutely unstable behavior at low momentum flux and/or density ratios, with attendant differences in shear layer vorticity evolution and rollup. These differences in stability characteristics are shown to have a significant effect on how one optimally employs external excitation to control jet penetration and spread, depending on the flow regime and specific engineering application. Yet recent unexpected observations on altered transverse jet structure under different flow conditions introduce a host of unanswered questions, primarily but not exclusively associated with the nature of molecular mixing, that make this canonical flowfield one that is of great interest for more extensive exploration.