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Sample records for hypervelocity dust bombardment

  1. Ion bombardment of interplanetary dust

    NASA Technical Reports Server (NTRS)

    Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is thought that a fraction of the interplanetary dust particles (IDP's) collected in the stratosphere by high-flying aircraft represent materials ejected from comets. An investigation is conducted regarding the effects of ion bombardment on these particles, taking into account information on ion tracks and carbon in IDP's and laboratory data on charged particle bombardment of surfaces. It is found that the observational discovery of particle tracks in certain IDP's clearly indicates the exposure of these particles to approximately 10,000 years of 1-AU equivalent solar-particle fluences. If some erasure of the tracks occurs, which is likely when an IDP enters the upper atmosphere, then somewhat longer times are implied. The effects of the erosion and enhanced adhesion produced by ions are considered.

  2. Hypervelocity Dust Injection for Plasma Diagnostic Applications

    NASA Astrophysics Data System (ADS)

    Ticos, Catalin

    2005-10-01

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

  3. Testing of a Plasmadynamic Hypervelocity Dust Accelerator

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

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

  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. Ejecta from Hypervelocity Dust Impacts Based on Light Flash Measurements

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  6. Time-resolved temperature measurements in hypervelocity dust impact

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  7. Hyper-velocity impact experiments with electrostatic dust accelerators

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  8. Hypervelocity Dust Impacts in Space and the Laboratory

    NASA Astrophysics Data System (ADS)

    Horanyi, Mihaly; Colorado CenterLunar Dust; Atmospheric Studies (CCLDAS) Team

    2013-10-01

    Interplanetary dust particles continually bombard all objects in the solar system, leading to the excavation of material from the target surfaces, the production of secondary ejecta particles, plasma, neutral gas, and electromagnetic radiation. These processes are of interest to basic plasma science, planetary and space physics, and engineering to protect humans and instruments against impact damages. The Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) has recently completed a 3 MV dust accelerator, and this talk will summarize our initial science results. The 3 MV Pelletron contains a dust source, feeding positively charged micron and sub-micron sized particles into the accelerator. We will present the technical details of the facility and its capabilities, as well as the results of our initial experiments for damage assessment of optical devices, and penetration studies of thin films. We will also report on the completion of our dust impact detector, the Lunar Dust Experiment (LDEX), is expected to be flying onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission by the time of this presentation. LDEX was tested, and calibrated at our dust accelerator. We will close by offering the opportunity to use this facility by the planetary, space and plasma physics communities.

  9. New experimental capability to investigate the hypervelocity micrometeoroid bombardment of cryogenic surfaces

    NASA Astrophysics Data System (ADS)

    Nelson, Andrew Oakleigh; Dee, Richard; Gudipati, Murthy S.; Horányi, Mihály; James, David; Kempf, Sascha; Munsat, Tobin; Sternovsky, Zoltán; Ulibarri, Zach

    2016-02-01

    Ice is prevalent throughout the solar system and beyond. Though the evolution of many of these icy surfaces is highly dependent on associated micrometeoroid impact phenomena, experimental investigation of these impacts has been extremely limited, especially at the impactor speeds encountered in space. The dust accelerator facility at the Institute for Modeling Plasmas, Atmospheres, and Cosmic Dust (IMPACT) of NASA's Solar System Exploration Research Virtual Institute has developed a novel cryogenic system that will facilitate future study of hypervelocity impacts into ice and icy regolith. The target consists of a copper block, cooled by liquid nitrogen, upon which layers of vapor-deposited ice, pre-frozen ice, or icy regolith can be built in a controlled and quantifiable environment. This ice can be grown from a variety of materials, including H2O, CH3OH, NH3, and slurries containing nanophase iron. Ice temperatures can be varied between 96 K and 150 K and ice thickness greater than 150 nm can be accurately measured. Importantly, the composition of ion plumes created during micrometeoroid impacts onto these icy layers can be measured even in trace amounts by in situ time-of-flight mass spectroscopy. In this paper, we present the fundamental design components of the cryogenic target chamber at IMPACT and proof-of-concept results from target development and from first impacts into thick layers of water ice.

  10. New experimental capability to investigate the hypervelocity micrometeoroid bombardment of cryogenic surfaces.

    PubMed

    Nelson, Andrew Oakleigh; Dee, Richard; Gudipati, Murthy S; Horányi, Mihály; James, David; Kempf, Sascha; Munsat, Tobin; Sternovsky, Zoltán; Ulibarri, Zach

    2016-02-01

    Ice is prevalent throughout the solar system and beyond. Though the evolution of many of these icy surfaces is highly dependent on associated micrometeoroid impact phenomena, experimental investigation of these impacts has been extremely limited, especially at the impactor speeds encountered in space. The dust accelerator facility at the Institute for Modeling Plasmas, Atmospheres, and Cosmic Dust (IMPACT) of NASA's Solar System Exploration Research Virtual Institute has developed a novel cryogenic system that will facilitate future study of hypervelocity impacts into ice and icy regolith. The target consists of a copper block, cooled by liquid nitrogen, upon which layers of vapor-deposited ice, pre-frozen ice, or icy regolith can be built in a controlled and quantifiable environment. This ice can be grown from a variety of materials, including H2O, CH3OH, NH3, and slurries containing nanophase iron. Ice temperatures can be varied between 96 K and 150 K and ice thickness greater than 150 nm can be accurately measured. Importantly, the composition of ion plumes created during micrometeoroid impacts onto these icy layers can be measured even in trace amounts by in situ time-of-flight mass spectroscopy. In this paper, we present the fundamental design components of the cryogenic target chamber at IMPACT and proof-of-concept results from target development and from first impacts into thick layers of water ice. PMID:26931872

  11. Hypervelocity dust impacts on the Wind spacecraft: Correlations between Ulysses and Wind interstellar dust detections

    NASA Astrophysics Data System (ADS)

    Wood, S. R.; Malaspina, David M.; Andersson, Laila; Horanyi, Mihaly

    2015-09-01

    The Wind spacecraft is positioned just sunward of Earth at the first Lagrange point, while the Ulysses spacecraft orbits above and below the ecliptic plane crossing the ecliptic as far from the Sun as the orbit of Jupiter (˜5 AU). While Wind does not carry a dedicated dust detector, we demonstrate the ability of Wind electric field measurements to detect hypervelocity dust impacts through their impact plasma signatures. Interstellar dust (ISD) and interplanetary dust particles are differentiated based on a yearly modulation of the ISD flux. Measurements of ISD flux variation by Wind are found to be in good agreement with ISD flux variation measured by Ulysses. While measurements of the ISD flow direction through the Solar System determined by Wind could not be directly compared to those from Ulysses, strong variation in ISD flow direction was observed during similar time periods by both spacecraft.

  12. Ejection and Lofting of Dust from Hypervelocity Impacts on the Moon

    NASA Astrophysics Data System (ADS)

    Hermalyn, B.; Schultz, P. H.

    2011-12-01

    Hypervelocity impact events mobilize and redistribute fine-grained regolith dust across the surfaces of planetary bodies. The ejecta mass-velocity distribution controls the location and emplacement of these materials. The current flux of material falling on the moon is dominated by small bolides and should cause frequent impacts that eject dust at high speeds. For example, approximately 25 LCROSS-sized (~20-30m diameter) craters are statistically expected to be formed naturally on the moon during any given earth year. When scaled to lunar conditions, the high-speed component of ejecta from hypervelocity impacts can be lofted for significant periods of time (as evidenced by the LCROSS mission results, c.f., Schultz, et al., 2010, Colaprete, et al., 2010). Even at laboratory scales, ejecta can approach orbital velocities; the higher impact speeds and larger projectiles bombarding the lunar surface may permit a significant portion of material to be launched closer to escape velocity. When these ejecta return to the surface (or encounter local topography), they impact at hundreds of meters per second or faster, thereby "scouring" the surface with low mass oblique impacts. While these high-speed ejecta represent only a small fraction of the total ejected mass, the lofting and subsequent ballistic return of this dust has the highest mobilization potential and will be directly applicable to the upcoming LADEE mission. A suite of hypervelocity impact experiments into granular materials was performed at the NASA Ames Vertical Gun Range (AVGR). This study incorporates both canonical sand targets and air-fall pumice dust to simulate the mechanical properties of lunar regolith. The implementation of a Particle Tracking Velocimetry (PTV) technique permits non-intrusive measurement of the ejecta velocity distribution within the ejecta curtain by following the path of individual ejecta particles. The PTV system developed at the AVGR uses a series of high-speed cameras (ranging

  13. The 3MV Hypervelocity Dust Accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Shu, A.; Collette, A.; Drake, K.; Horanyi, M.; Kempf, S.; Munsat, T.; Northway, P.; Robertson, S.; Sternovsky, Z.; Thomas, E.; Gruen, E.; Srama, R.

    2011-11-01

    Micrometeorite impacts and dusty plasma phenomena can be found in a wide variety of subjects. In many extraplanetary systems, such as in deep space and on airless bodies such as asteroids or the moon, dusty plasmas play a large role in the basic scientific evolution of the environment. Dust can also be captured and studied in dust astronomy in order to better understand the evolution of our universe, similarly to how photons are used in traditional astronomy. At the Colorado Center for Lunar Dust and Atmospheric Studies, we have developed a 3MV hypervelocity dust accelerator in order to study these and other applications of dust and dusty plasmas. This facility is capable of accelerating micron sized dust particles up to 10's of km/s. In addition to this we have several vacuum chambers used for dusty plasma experiments. The large Lunar Environment Impact Laboratory (LEIL) test chamber will be used to study dust levitation, space weathering, and lunar exosphere evolution. A smaller ultrahigh vacuum chamber will be used to detect neutral species in micrometeorite impact ejecta and detect and analyze impact flashes. In addition to this work, graphite tokamak wall tile material will be placed into the beam path to determine damage characteristics from dust in fusion systems.

  14. 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.

  15. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies.

    PubMed

    Shu, Anthony; Collette, Andrew; Drake, Keith; Grün, Eberhard; Horányi, Mihály; Kempf, Sascha; Mocker, Anna; Munsat, Tobin; Northway, Paige; Srama, Ralf; Sternovsky, Zoltán; Thomas, Evan

    2012-07-01

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Institüt für Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10(-7) torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10(-10) torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments. PMID:22852725

  16. 3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies

    SciTech Connect

    Shu, Anthony; Horanyi, Mihaly; Kempf, Sascha; Thomas, Evan; Collette, Andrew; Drake, Keith; Northway, Paige; Gruen, Eberhard; Mocker, Anna; Munsat, Tobin; Srama, Ralf; and others

    2012-07-15

    A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Instituet fuer Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10{sup -7} torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10{sup -10} torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

  17. Changes of Dust Grain Properties Under Particle Bombardment

    SciTech Connect

    Pavlu, J.; Richterova, I.; Safrankova, J.; Nemecek, Z.; Fujita, D.

    2008-09-07

    The dust in space environments is exposed to particle bombardment. Under an impact of ions, electrons, and photons, the charge of a particular grain changes and, in some cases, the grain structure can be modified. The present study deals with spherical melamine formaldehyde resin grains that are frequently used in many dusty plasmas and microgravity experiments and it concentrates on the influence of the electron beam impact on a grain size. We have performed series of experiments based on the SEM technique. Our investigation has shown that the electron impact can cause a significant increase of the grain size. We discuss changes of material properties and consequences for its applications in laboratory and space experiments.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

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

  20. 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.

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

    PubMed

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

    2008-04-18

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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. Stability of carbonaceous dust analogues and glycine under UV irradiation and electron bombardment.

    PubMed

    Maté, Belén; Tanarro, Isabel; Moreno, Miguel A; Jiménez-Redondo, Miguel; Escribano, Rafael; Herrero, Víctor J

    2014-01-01

    The effect of UV photon (120-200 nm) and electron (2 keV) irradiation of analogues of interstellar carbonaceous dust and of glycine were investigated by means of IR spectroscopy. Films of hydrogenated amorphous carbon (HAC), taken as dust analogues, were found to be stable under UV photon and electron bombardment. High fluences of photons and electrons, of the order of 10(19) cm(-2), were needed for a film depletion of a few percent. UV photons were energetically more effective than electrons for depletion and led to a certain dehydrogenation of the HAC samples, whereas electrons led seemingly to a gradual erosion with no appreciable changes in the hydrocarbon structure. The rates of change observed may be relevant over the lifetime of a diffuse cloud, but cannot account for the rapid changes in hydrocarbon IR bands during the evolution of some proto-planetary nebulae. Glycine samples under the same photon and electron fluxes decay at a much faster rate, but tend usually to an equilibrium value different from zero, especially at low temperatures. Reversible reactions re-forming glycine, or the build-up of less transparent products, could explain this behavior. CO2 and methylamine were identified as UV photoproducts. Electron irradiation led to a gradual disappearance of the glycine layers, also with formation of CO2. No other reaction products were clearly identified. The thicker glycine layers (a few hundred nm) were not wholly depleted, but a film of the order of the electron penetration depth (80 nm), was totally destroyed with an electron fluence of -1 x 10(18) cm(-2). A 60 nm ice layer on top of glycine provided only partial shielding from the 2 keV electrons. From an energetic point of view, 2 keV electrons are less efficient than UV photons and, according to literature data, much less efficient than MeV protons for the destruction of glycine. The use of keV electrons to simulate effects of cosmic rays on analogues of interstellar grains should be taken with

  9. Space Weathering of airless bodies in the Solar System - Combining hypervelocity dust impacts with energetic irradiation experiments

    NASA Astrophysics Data System (ADS)

    Fiege, K.; Bennett, C.; Guglielmino, M.; Orlando, T. M.; Trieloff, M.; Srama, R.

    2015-12-01

    The chemical and mineralogical characterization of meteorites and their parent asteroids provides us with information about the processes and conditions during the formation of the inner Solar System. However, linking meteorites to their parent bodies is problematic. Astronomical observations aim to reconstruct the surface properties of these bodies primarily by visible and infrared spectra, but space weathering severely modifies the optical, compositional and physical properties of thin surface layers and thus precludes proper identification of chemistry and mineralogy. The effects of space weathering have been experimentally studied mainly with respect to ion bombardment and sputtering. Other studies aimed to simulate the influence of micrometeoroid bombardment by using laser ablation techniques. However, there is sufficient evidence that laser ablation does not realistically lead to the same effects as produced during real micrometeorite impacts. We performed micrometeorite bombardment using a 2MV dust accelerator at the Institute for Space Systems at University of Stuttgart, Germany, capable of generating impact speeds up to 100 km s-1. These results are combined with energetic irradiation experiments at the Electron and Photon Induced Chemistry on Surfaces (EPICS) laboratory at Georgia Institute of Technology, USA. By simulating highly realistic irradiation conditions, we are able to investigate the processes of particle and solar wind irradiation on solid planetary surfaces and study the formation of e.g., nanophase iron in minerals, the effects on hydrous minerals regarding their volatile budgets, or possible OH-formation in nominally anhydrous minerals and relate these to their optical properties. Using a variety of minerals, this work aims to contribute to a better understanding of the general alteration mechanisms in space environments in dependence of weathering agent and available material. We here present the results of initial comparison analysis and

  10. Abundant Circumstellar Silica Dust and SiO Gas Created by a Giant Hypervelocity Collision in the 12 Myr HD172555 System

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.; Chen, C. H.; Wyatt, M. C.; Morlok, A.; Song, I.; Bryden, G.; Sheehan, P.

    2009-09-01

    We have used the IRS Spectrograph onboard the Spitzer Space Telescope to study the warm dust orbiting around the 29 pc distant β Pic analogue star HD172555. The dust mineralogy is very peculiar, composed primarily of highly refractory, non-equilibrium materials, with 3/4 of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra (non-equilibrium glassy silicas found in impact and magmatic systems) are required to fit the data. The best-fit model size distribution for the observed fine dust is dn/da = a-3.95±0.10. This steep a size distribution argues for a fresh source of material within the last 0.1 Myr. The location of the dust with respect to the star is at 5.8 ± 0.6 AU, within the terrestrial planet formation region but at the outer edge of any possible terrestrial habitability zone. The mass of fine dust is 4 x 1019 - 2 x 1020 kg, equivalent to a 150 - 200 km radius asteroid. Significant emission features centered at 4 and 8 µm due to fluorescing SiO gas are also found. Roughly 1022 kg of SiO gas, formed by vaporizing silicate rock, is also present in the system, and a separate population of very large, cool grains, massing 1021 - 1022 kg and equivalent to the largest sized asteroid currently found in the Solar System's main asteroid belt, dominates the solid circumstellar material by mass. The makeup of the observed dust and gas, and the noted lack of a dense circumstellar gas disk, strong primary x-ray activity, or an extended disk of β meteroids argues that the source of the observed circumstellar materials is a giant hypervelocity (> 10 km sec-1) impact between large rocky planetesimals, similar to the ones which formed the Moon and which stripped the surface crustal material off of Mercury's surface.

  11. Abundant Circumstellar Silica Dust and SiO Gas Created by a Giant Hypervelocity Collision in the 12 Myr HD172555 System

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.; Chen, C. H.; Wyatt, M. C.; Morlok, A.; Song, I.; Bryden, G.; Sheehan, P.

    2010-01-01

    We have used the InfraRed Spectrograph on the Spitzer Space Telescope to study the fine dust orbiting around the 29 pc distant β Pic analogue star HD172555. The dust mineralogy is is very peculiar, composed primarily of highly refractory, non-equilibrium materials, with 3/4 of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra (non-equilibrium glassy silicas found in impact and magmatic systems) are required to fit the data. The best-fit model size distribution for the observed fine dust is dn/da = a-3.95±0.10. This steep a size distribution argues for a fresh source of material within the last 0.1 Myr. The location of the dust with respect to the star is at 5.8 ± 0.6 AU, within the terrestrial planet formation region but at the outer edge of any possible terrestrial habitability zone. The mass of fine dust is 4 x 1019 - 2 x 1020 kg, equivalent to a 150 - 200 km radius asteroid. Significant emission features centered at 4 and 8 µm due to fluorescing SiO gas are also found. Roughly 1022 kg of SiO gas, formed by vaporizing silicate rock, is also present in-system, and a separate population of very large, cool grains, massing 1021 - 1022 kg and equivalent to the largest sized asteroid currently found in the Solar System's main asteroid belt, dominates the solid circumstellar material by mass. The makeup of the observed dust and gas, and the noted lack of a dense circumstellar gas disk, strong primary x-ray activity, or an extended disk of β meteroids argues that the source of the observed circumstellar materials is a giant hypervelocity (> 10 km sec-1) impact between large rocky planetesimals, similar to the ones which formed the Moon and which stripped the surface crustal material off of Mercury's surface.

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

    SciTech Connect

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

    2008-04-15

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

  13. ABUNDANT CIRCUMSTELLAR SILICA DUST AND SiO GAS CREATED BY A GIANT HYPERVELOCITY COLLISION IN THE {approx}12 MYR HD172555 SYSTEM

    SciTech Connect

    Lisse, C. M.; Chen, C. H.; Wyatt, M. C.; Morlok, A.; Song, I.; Bryden, G.; Sheehan, P. E-mail: cchen@stsci.edu E-mail: A.Morlok@open.ac.uk E-mail: Geoffrey.Bryden@jpl.nasa.gov

    2009-08-20

    The fine dust detected by infrared (IR) emission around the nearby {beta} Pic analog star HD172555 is very peculiar. The dust mineralogy is composed primarily of highly refractory, nonequilibrium materials, with approximately three quarters of the Si atoms in silica (SiO{sub 2}) species. Tektite and obsidian lab thermal emission spectra (nonequilibrium glassy silicas found in impact and magmatic systems) are required to fit the data. The best-fit model size distribution for the observed fine dust is dn/da = a {sup -3.95{+-}}{sup 0.10}. While IR photometry of the system has stayed stable since the 1983 IRAS mission, this steep a size distribution, with abundant micron-sized particles, argues for a fresh source of material within the last 0.1 Myr. The location of the dust with respect to the star is at 5.8 {+-} 0.6 AU (equivalent to 1.9 {+-} 0.2 AU from the Sun), within the terrestrial planet formation region but at the outer edge of any possible terrestrial habitability zone. The mass of fine dust is 4 x 10{sup 19}-2 x 10{sup 20} kg, equivalent to a 150-200 km radius asteroid. Significant emission features centered at 4 and 8 {mu}m due to fluorescing SiO gas are also found. Roughly 10{sup 22} kg of SiO gas, formed by vaporizing silicate rock, is also present in the system, and a separate population of very large, cool grains, massing 10{sup 21}-10{sup 22} kg and equivalent to the largest sized asteroid currently found in the solar system's main asteroid belt, dominates the solid circumstellar material by mass. The makeup of the observed dust and gas, and the noted lack of a dense circumstellar gas disk, strong stellar X-ray activity, and an extended disk of {beta} meteoroids argues that the source of the observed circumstellar materials is a giant hypervelocity (>10 km s{sup -1}) impact between large rocky planetesimals, similar to the ones which formed the Moon and which stripped the surface crustal material off of Mercury's surface.

  14. Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Brown, Warren R.

    2015-08-01

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

  15. Hypervelocity sub 10-micron impacts into aluminium foil: new experimental data and implications for comet 81P/Wild-2's dust fluence

    NASA Astrophysics Data System (ADS)

    Price, Mark C.; Kearsley, Anton T.; Burchell, Mark J.; Horz, Friedrich; Cole, Mike J.

    2009-06-01

    Recent experimental work (Price, M. C. et. al., LPSC XXXX, #1564, 2009) has shown that the lip-to-lip diameter of hypervelocity impact craters at micron-scales (Dp< 10 microns) is a non-linear function of the impactor's diameter (Dp). We present data for monodisperse silica projectiles impacting aluminium-1100 and elemental aluminium at 6.1 kmsec and discuss the implications of this effect for the Stardust fluence calibration for micron-scale particles (which make up the majority of the impactor flux). Hydrocodes have been used to investigate the potential causes of the phenomena and the results are presented.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Infrared Spectroscopy of Wild 2 Particle Hypervelocity Tracks in Stardust Aerogel: Evidence for the presence of Volatile Organics in Comet Dust

    SciTech Connect

    Bajt, S; Sandford, S A; Flynn, G J; Matrajt, G; Snead, C J; Westphal, A J; Bradley, J P

    2007-08-28

    Infrared spectroscopy maps of some tracks, made by cometary dust from 81P/Wild 2 impacting Stardust aerogel, reveal an interesting distribution of volatile organic material. Out of six examined tracks three show presence of volatile organic components possibly injected into the aerogel during particle impacts. When particle tracks contained excess volatile organic material, they were found to be -CH{sub 2}-rich. Off-normal particle tracks could indicate impacts by lower velocity particles that could have bounced off the Whipple shield, therefore carry off some contamination from it. However, this theory is not supported by data that show excess organic-rich material in normal and off-normal particle tracks. It is clear that the population of cometary particles impacting the Stardust aerogel collectors also include grains that contained little or none of this volatile organic component. This observation is consistent with the highly heterogeneous nature of the collected grains, as seen by a multitude of other analytical techniques. We propose that at least some of the volatile organic material might be of cometary origin based on supporting data shown in this paper. However, we also acknowledge the presence of carbon (primarily as -CH{sub 3}) in the original aerogel, which complicates interpretation of these results.

  2. Simulating plasma production from hypervelocity impacts

    SciTech Connect

    Fletcher, Alex Close, Sigrid; Mathias, Donovan

    2015-09-15

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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Hypervelocity impacts into graphite

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  8. 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.

  9. 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).

  10. Electromagnetic Pulses Generated by Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Close, S.

    2011-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  12. 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.

  13. 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.

  14. Sharp Hypervelocity Aerodynamic Research Probe

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  15. 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.

  16. Fast Atom Bombardment Mass Spectrometry.

    ERIC Educational Resources Information Center

    Rinehart, Kenneth L., Jr.

    1982-01-01

    Discusses reactions and characteristics of fast atom bombardment (FAB) mass spectroscopy in which samples are ionized in a condensed state by bombardment with xenon or argon atoms, yielding positive/negative secondary ions. Includes applications of FAB to structural problems and considers future developments using the technique. (Author/JN)

  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 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.

  19. 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.

  20. 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.

  1. 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.

  2. Intact capture of hypervelocity projectiles.

    PubMed

    Tsou, P

    1990-01-01

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

  3. On the Nature of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

    Ginsburg, Idan

    2013-12-01

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

  4. Deducing dust emission mechanisms from field measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field observations are needed to both develop and test theories on dust emission for use in global modeling systems. The mechanism of dust emission (aerodynamic entrainment, saltation bombardment, aggregate disintegration) and the amount and particle-size distribution of emitted dust may vary under ...

  5. AXAF hypervelocity impact test results

    NASA Technical Reports Server (NTRS)

    Frost, Cynthia L.; Rodriguez, Pedro I.

    1997-01-01

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

  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. 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.

  9. Element fracture technique for hypervelocity impact simulation

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  10. Crater and cavity depth in hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Kadono, T.; Fujiwara, A.

    2003-04-01

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

  11. Effects of barrel joints on hypervelocity projectiles

    SciTech Connect

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

    1987-01-01

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

  12. Computational design of hypervelocity launchers

    SciTech Connect

    Trucano, T.; Chhabildas, L.

    1993-12-31

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

  13. Dust torus around Mars

    NASA Technical Reports Server (NTRS)

    Juhasz, Antal; Horanyi, Mihaly

    1995-01-01

    We investigate the orbital dynamics of small dust particles generated via the continuous micrometeoroid bombardment of the Martian moons. In addition to Mar's oblateness, we also consider the radiation pressure perturbation that is complicated by the planet's eccentric orbit and tilted rotational axis. Considering the production rates and the lifetimes of dust grains, we show that particles from Deimos with radii of about 15 micrometers are expected to dominate the population of a permanently present and tilted dust torus. This torus has an estimated peak number density of approximately equals 5 x 10(exp -12)/cu cm and an optical depth of approximately equals 4 x 10(exp -8).

  14. Progress in hypervelocity impact and protection

    NASA Astrophysics Data System (ADS)

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

    Starting with an introduction into the field of hypervelocity impacts, an overview of current activities in the area of protection against space debris and micrometeoroids is given. After a description of the relevant distributions of debris masses and velocities in orbit, the physical phenomena during a hypervelocity impact will be highlighted using high -speed photographs and flash x-ray pictures. Progress in shield design against space debris can be achieved only, when a combined approach of advanced numerical methods, specific mat erial models and experimental determination of input parameters for these models is used. Examples of experimental methods for material characterization are given, covering the range from quasi static to very high strain rates for materials like Nextel and carbon fiber reinforced materials. Mesh free numerical methods have extraordinary capabilities in the simulation of extreme material behaviour including complete failure with phase changes, combined with shock wave phenomena and the interaction with structural components. In addition to numerical methods, engineering models, summarizing knowledge gained from experiments and/or from numerical simulation, play an important role, for example for system studies and parametric investigations. New material types are developed for applications outside of hypervelocity impact and protection. A permanent screening of new materials with respect to their behaviour under hypervelocity impact loads is necessary to identify materials with a potential for increased protection efficiency. Aim of our paper is to demonstrate the favours of combining numerical methods, material modelling, detailed experimental methods and engineering formulas in shield design. We do this by discussing the following examples: - Hypervelocity impact on pressure vessels: Pressure vessels are integral components of any spacecraft. Therefore research has been focussed on their behaviour under the combined load of internal

  15. 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.

  16. 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.

  17. Ion bombardment in RF photoguns

    SciTech Connect

    Pozdeyev,E.; Kayran, D.; Litvinenko, V. N.

    2009-05-04

    A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the Rf field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.

  18. Cereal transformation through particle bombardment

    NASA Technical Reports Server (NTRS)

    Casas, A. M.; Kononowicz, A. K.; Bressan, R. A.; Hasegawa, P. M.; Mitchell, C. A. (Principal Investigator)

    1995-01-01

    The review focuses on experiments that lead to stable transformation in cereals using microprojectile bombardment. The discussion of biological factors that affect transformation examines target tissues and vector systems for gene transfer. The vector systems include reporter genes, selectable markers, genes of agronomic interest, and vector constructions. Other topics include physical parameters that affect DNA delivery, selection of stably transformed cells and plant regeneration, and analysis of gene expression and transmission to the progeny.

  19. Characterizing the Early Impact Bombardment

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.

    2005-01-01

    The early bombardment revealed in the larger impact craters and basins on the moon was a major planetary process that affected all bodies in the inner solar system, including the Earth and Mars. Understanding the nature and timing of this bombardment is a fundamental planetary problem. The surface density of lunar impact craters within a given size range on a given lunar surface is a measure of the age of that surface relative to other lunar surfaces. When crater densities are combined with absolute radiometric ages determined on lunar rocks returned to Earth, the flux of large lunar impactors through time can be estimated. These studies suggest that the flux of impactors producing craters greater than 1 km in diameter has been approximately constant over the past approx. 3 Gyr. However, prior to 3.0 - 3.5 Gyr the impactor flux was much larger and defines an early bombardment period. Unfortunately, no lunar surface feature older than approx. 4 Gyr is accurately dated, and the surface density of craters are saturated in most of the lunar highlands. This means that such data cannot define the impactor flux between lunar formation and approx. 4 Gyr ago.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

  5. Silica Aerogel Captures Cosmic Dust Intact

    NASA Technical Reports Server (NTRS)

    Tsou, P.

    1994-01-01

    The mesostructure of silica aerogel resembles stings of grapes, ranging in size from 10 to 100 angstrom. This fine mesostructure transmits nearly 90 percent of incident light in the visible, while providing sufficiently gentle dissipation of the kinetric energy of hypervelocity cosmic dust particles to permit their intact capture. We introduced silica aerogel in 1987 as capture medium to take advantage of its low density, fine mesostruicture and most importantly, its transparency, allowing optical location of captured micron sized particles.

  6. 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.

  7. Hypervelocity impact calculations using CTH: Case studies

    SciTech Connect

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

    1989-01-01

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

  8. ALE advantage in hypervelocity impact calculations

    SciTech Connect

    Gerassimenko, M.; Rathkopf, J.

    1998-10-01

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

  9. 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.

  10. 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.

  11. 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.

  12. Plasma-Based Detector of Outer-Space Dust Particles

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce; Brinza, David E.; Henry, Michael D.; Clay, Douglas R.

    2006-01-01

    A report presents a concept for an instrument to be flown in outer space, where it would detect dust particles - especially those associated with comets. The instrument would include a flat plate that would intercept the dust particles. The anticipated spacecraft/dust-particle relative speeds are so high that the impingement of a dust particle on the plate would generate a plasma cloud. Simple electric dipole sensors located equidistantly along the circumference of the plate would detect the dust particle indirectly by detecting the plasma cloud. The location of the dust hit could be estimated from the timing of the detection pulses of the different dipoles. The mass and composition of the dust particle could be estimated from the shapes and durations of the pulses from the dipoles. In comparison with other instruments for detecting hypervelocity dust particles, the proposed instrument offers advantages of robustness, large collection area, and simplicity.

  13. Subsurface Deformation of Nonporous Rocks Induced by Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  14. 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.

  15. 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.

  16. NASA White Sands Test Facility Remote Hypervelocity Test Laboratory

    NASA Video Gallery

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

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Ion bombardment investigations of impregnated cathodes

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaobing; Gaertner, Georg

    2003-06-01

    Ion bombardment is one of the important factors limiting the performance of impregnated cathodes (=Ba dispenser cathodes) in high end television tubes or in colour monitor tubes. Hence, when designing a new gun with, e.g. higher electron beam current density, it is important also to model the influence of ion bombardment. Therefore, relations between basic parameters as a function of temperature need to be known quantitatively. In this paper, the emission slump of impregnated cathodes has been analyzed in a diode configuration in UHV with a differentially pumped Ar ion gun. The emission degeneration during and regeneration periods after ion bombardment have been investigated as function of cathode temperature, ion current and ion energy. One of the important results is, that the degeneration time coefficient is only weakly dependent on ion energy. The data matrix obtained can be used to improve the ion bombardment model applied in new electron gun design.

  3. Hypervelocity impact effects on solar cells. Final technical report

    SciTech Connect

    Rose, M.F.

    1993-01-01

    One of the space hazards of concern is the problem of natural matter and space debris impacting spacecraft. This phenomena has been studied since the early sixties and a methodology has been established to determine the relative abundance of meteoroids as a function of mass. As the mass decreases, the probability of suffering collisions increases, resulting in a constant bombardment from particles in the sub-micron range. The composition of this cosmic dust is primarily Fe, Ni, Al, Mg, Na, Ca, Cr, H, O, and Mn. 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 purpose of this work was to subject samples from solar power arrays to debris flux typical of what would be encountered in space, and measure the degradation of the panels after impact.

  4. Levitated lunar surface dust as evidenced by the LEAM experiment

    NASA Astrophysics Data System (ADS)

    Auer, S.; Berg, O. E.

    2008-09-01

    The Lunar Ejecta and Meteorites (LEAM) experiment was deployed by the Apollo 17 astronauts in the Taurus-Littrow area of the moon in December 1972. The science objectives of LEAM were (1) to investigate the interplanetary dust flux (primary particles) bombarding the lunar surface; (2) to investigate the properties of the lunar ejecta (secondary) particles; (3) to follow the temporal variability of these fluxes along the lunar orbit; and (4) to observe interstellar particles. The design and expected performance was similar to the dust experiments flown on Pioneers 8 and 9 in heliocentric orbits [1]. They responded to plasma generated by hypervelocity dust impacts. The pulse height generated was a function of mv2.6 of the particle (where m [g] is its mass and v [km/s] is its impact velocity) with a detection threshold of typically m = 10-13 g at v = 25 km s-1. Particle velocity was measured directly by its time of flight between two films spaced 5 cm apart. The LEAM contained three sensor systems. The east sensor was pointed 25° north of east, so that once per lunation its field of view swept into the direction of the interstellar dust flow. The west sensor was pointing in the opposite direction, while the up sensor was parallel to the lunar surface and viewing particles coming from above. Only the west sensor was lacking the front film. It was designed to identify low-speed ejecta impacts that were not expected to penetrate the front film. It soon became evident that most events registered by the sensors had to be attributed not to meteorites or lunar ejecta but to slow moving, highly charged lunar surface dust. Most puzzling were two facts: (1) the event rates increased with the passage of the terminators and (2) the events registered in the front film only and with the maximum possible pulse height. The event rate started to increase up to 60 hours before the local sunrise and persisted after sunrise for about 30-60 hours. In this interval the east sensor's rates

  5. 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.

  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. Hydrocode modelling of hypervelocity impacts on ice

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  8. Further investigations of oblique hypervelocity impact phenomena

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1988-01-01

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

  9. Projectile development for railguns using hypervelocity preacceleration

    NASA Astrophysics Data System (ADS)

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

    1992-03-01

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

  10. 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.

  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. 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.

  14. 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.

  15. Characteristics of plasma generated by hypervelocity impact

    SciTech Connect

    Song, Weidong; Li, Jianqiao; Ning, Jianguo

    2013-09-15

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

  16. 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.

  17. Lunar dust: The Hazard and Astronaut Exposure Risks

    NASA Astrophysics Data System (ADS)

    Cain, John R.

    2010-12-01

    This paper reviews the characterisation of lunar dust or regolith, the toxicity of the dust and associated health effects, the techniques for assessing the health risks from dust exposure and describes the measures used or being developed to mitigate exposure. Lunar dust is formed from micrometeorite impacts onto the Moon's surface. The hypervelocity impacts result in communition and the formation of sharp and clingy agglutinates. The dust particles vary in size with the smallest being less than 10 μm. If the chemical reactive particles are deposited in the lungs, they may cause respiratory disease. During lunar exploration, the astronaut's spacesuits will become contaminated with lunar dust. The dust will be released into the atmosphere when the suits are removed. The exposure risks to health will need to be assessed by relating to a permissible exposure limit. During the Apollo missions, the astronauts were exposed to lunar dust. Acute health effects from dust inhalation exposure included sore throat, sneezing and coughing. Long-term exposure to the dust may cause a more serious respiratory disease similar to silicosis. On future missions the methods used to mitigate exposure will include providing high air recirculation rates in the airlock, the use of a "Double Shell Spacesuit" so that contaminated spacesuits are removed before entering the airlock, the use of dust shields to prevent dust accumulating on surfaces, the use of high gradient magnetic separation to remove surface dust and the use of solar flux to sinter and melt the regolith around the spacecraft.

  18. In-flight detection of small hypervelocity particles.

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  19. Hypervelocity impact testing of non-metallic materials

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1990-01-01

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

  20. Hypervelocity impact cratering - A catastrophic terrestrial geologic process

    NASA Astrophysics Data System (ADS)

    Grieve, Richard A. F.

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

  1. Ion bombardment and disorder in amorphous silicon

    SciTech Connect

    Sidhu, L.S.; Gaspari, F.; Zukotynski, S.

    1997-07-01

    The effect of ion bombardment during growth on the structural and optical properties of amorphous silicon are presented. Two series of films were deposited under electrically grounded and positively biased substrate conditions. The biased samples displayed lower growth rates and increased hydrogen content relative to grounded counterparts. The film structure was examined using Raman spectroscopy. The transverse optic like phonon band position was used as a parameter to characterize network order. Biased samples displayed an increased order of the amorphous network relative to grounded samples. Furthermore, biased samples exhibited a larger optical gap. These results are correlated and attributed to reduced ion bombardment effects.

  2. Laboratory Micrometeroid/Dust Ablation Studies

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Horanyi, M.; Janches, D.; Munsat, T. L.; Plane, J. M. C.; Simolka, J.; Sternovsky, Z.

    2014-12-01

    Each day, somewhere between 5-270 tonnes of meteoric material ablates in Earth's upper atmosphere. Thisenormous range is significant because the Interplanetary Dust Particle (IDP) input has implications in ourunderstanding of meteor transport in the atmosphere, the formation of layers of metal atoms and ions,nucleation of noctilucent clouds, effects on stratospheric aerosols and O3 chemistry, and dust evolution inour solar system. As the dust ablates, it produces light, as well as a plasma trail of ionized atmosphericatoms and electrons. These meteor signatures are detected by photographic means, or by radar, but thereremain uncertainties in the luminous efficiency and ionization coefficient of meteors - two parameters thatare essential to evaluate densities, masses, height distributions and fluxes. Precise measurements of theseparameters would allow for not only an understanding of the layers of metal atoms and ions and meteoricsmoke particles in the mesosphere and lower thermosphere, but also would allow for the Earth's atmosphereto be used as a dust detector to detect and characterize the dust environment in our solar system. This work discusses the preliminary results of the new dust ablation facility at the 3 MV hypervelocity dust accelerator at the Institute for Modeling Plasma, Atmospheres and Cosmic Dust (IMPACT) at the University of Colorado, which aims to characterize the ionization coefficient and luminous efficiency of ablating micrometeroids.

  3. The Velocity Distribution of Hypervelocity Stars

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  4. Dynamic Optical Investigations of Hypervelocity Impact Damage

    NASA Astrophysics Data System (ADS)

    Lamberson, Leslie Elise

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

  5. 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

  6. Electrical signatures of hypervelocity impact plasma with applications in in-situ particle detection

    NASA Astrophysics Data System (ADS)

    Rudolph, M.; Schimmerohn, M.; Osterholz, J.; Schäfer, F.

    2014-08-01

    Hypervelocity impacts of micrometeoroid and space debris particles can produce a highly transient plasma cloud that shows a spectrum of distinct electrical phenomena ranging from charge production to electrostatic field and electromagnetic wave generation. The coupling of these effects to electrical probes can be used as a means of in-situ debris detection to monitor the polluted orbits around the Earth. In the past, some detectors were built mainly for the detection of natural dust populations in space, such as a long heritage of charge collection detectors. In addition, several radio astronomy and ambient plasma instruments that were not specifically dedicated to particle detection revealed impact-induced anomalies during interplanetary missions. Most of them were explained by the interaction of electrically sensitive probes with free charges produced upon impact. For the application in low Earth orbits, one needs to take into account, that the man-made debris population differs from natural populations in many regards, as does the plasma environment between interplanetary space and in orbits close to Earth. The paper at hand gives a summary of detectors with flight heritage and devises a first concept for in situ space debris detectors in low Earth orbit by exploiting past experience with dust detectors in deep space.

  7. Processing and Synthesis of Pre-Biotic Chemicals in Hypervelocity Impacts

    NASA Technical Reports Server (NTRS)

    Brickerhoff, W. B.; Managadze, G. G.; Chumikov, A. E.; Managadze, N. G.

    2005-01-01

    Hypervelocity impacts (HVIs) may have played a significant role in establishing the initial organic inventory for pre-biotic chemistry on the Earth and other planetary bodies. In addition to the delivery of organic compounds intact to planetary surfaces, generally at velocities below approx.20 km/s, HVIs also enable synthesis of new molecules. The cooling post-impact plasma plumes of HVIs in the interstellar medium (ISM), the protosolar nebula (PSN), and the early solar system comprise pervasive conditions for organic synthesis. Such plasma synthesis (PS) can operate over many length scales (from nm-scale dust to planets) and energy scales (from molecular rearrangement to atomization and recondensation). HVI experiments with the flexibility to probe the highest velocities and distinguish synthetic routes are a high priority to understand the relevance of PS to exobiology. We describe here recent studies of PS at small spatial scales and extremely high velocities with pulsed laser ablation (PLA). PLA can simulate the extreme plasma conditions generated in impacts of dust particles at speeds of up to 100 km/s or more. When applied to carbonaceous solids, new and pre-biotically relevant molecular species are formed with high efficiency [1,2].

  8. 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.

  9. 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.

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

    SciTech Connect

    Cloutman, L.D.

    1991-01-24

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

  11. 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.

  12. Acoustic signals generated in piezoelectric lead zirconate titanate elements by direct bombardment with xenon ions

    NASA Astrophysics Data System (ADS)

    Miyachi, T.; Nakamura, Y.; Kuraza, G.; Fujii, M.; Nagashima, A.; Hasebe, N.; Kobayashi, M. N.; Kobayashi, S.; Miyajima, M.; Mori, K.; Okudaira, O.; Yamashita, N.; Shibata, H.; Murakami, T.; Uchihori, Y.; Okada, N.

    2006-12-01

    Acoustic signals were observed with a lead-zirconate-titanate (PZT) element that was directly irradiated with a 368 MeV/n xenon beam. Using an array comprising PZT elements, the energy loss in the PZT was studied. These elements are sensitive to an energy deposit of 100 nJ. A series of values of output voltage vs. integrated thickness of PZT was represented along a line similar to the ionization loss calculated by the Bethe-Bloch formula. The induced voltage was attributed to several processes—ionization, thermal, elastic, and piezoelectric processes. This study describes the possible applications of the PZT element as an active medium for calorimeters and a monitor for hypervelocity impact of space dust.

  13. Interplanetary and Interstellar Dust Observed by the Wind/WAVES Electric Field Instrument

    NASA Technical Reports Server (NTRS)

    Malaspina, David; Horanyi, M.; Zaslavsky, A.; Goetz, K.; Wilson, L. B., III; Kersten, K.

    2014-01-01

    Observations of hypervelocity dust particles impacting the Wind spacecraft are reported here for the first time using data from the WindWAVES electric field instrument. A unique combination of rotating spacecraft, amplitude-triggered high-cadence waveform collection, and electric field antenna configuration allow the first direct determination of dust impact direction by any spacecraft using electric field data. Dust flux and impact direction data indicate that the observed dust is approximately micron-sized with both interplanetary and interstellar populations. Nanometer radius dust is not detected by Wind during times when nanometer dust is observed on the STEREO spacecraft and both spacecraft are in close proximity. Determined impact directions suggest that interplanetary dust detected by electric field instruments at 1 AU is dominated by particles on bound trajectories crossing Earths orbit, rather than dust with hyperbolic orbits.

  14. 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

  15. Dust ablation in Pluto's atmosphere

    NASA Astrophysics Data System (ADS)

    Horanyi, Mihaly; Poppe, Andrew; Sternovsky, Zoltan

    2016-04-01

    Based on measurements by dust detectors onboard the Pioneer 10/11 and New Horizons spacecraft the total production rate of dust particles born in the Edgeworth Kuiper Belt (EKB) has been be estimated to be on the order of 5 ṡ 103 kg/s in the approximate size range of 1 - 10 μm. Dust particles are produced by collisions between EKB objects and their bombardment by both interplanetary and interstellar dust particles. Dust particles of EKB origin, in general, migrate towards the Sun due to Poynting-Robertson drag but their distributions are further sculpted by mean-motion resonances as they first approach the orbit of Neptune and later the other planets, as well as mutual collisions. Subsequently, Jupiter will eject the vast majority of them before they reach the inner solar system. The expected mass influx into Pluto atmosphere is on the order of 200 kg/day, and the arrival speed of the incoming particles is on the order of 3 - 4 km/s. We have followed the ablation history as function of speed and size of dust particles in Pluto's atmosphere, and found that volatile rich particles can fully sublimate due to drag heating and deposit their mass in narrow layers. This deposition might promote the formation of the haze layers observed by the New Horizons spacecraft. This talk will explore the constraints on the composition of the dust particles by comparing the altitude of the deposition layers to the observed haze layers.

  16. 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

  17. Lunar Dust Experiment (LDEX): First Results

    NASA Astrophysics Data System (ADS)

    Horanyi, Mihaly; Gagnard, Sam; Gathright, David; Gruen, Eberhard; James, David; Kempf, Sascha; Lankton, Mark; Srama, Ralf; Sternovsky, Zoltan; Szalay, Jamey

    2014-05-01

    The lunar dust environment is expected to be dominated by submicron-sized dust particles released from the Moon due to the continual bombardment by micrometeoroids, and possibly due to UV radiation and plasma-induced near-surface intense electric fields. The Lunar Dust EXperiment (LDEX) instrument is designed to map the spatial and temporal variability of the dust size and density distributions in the lunar environment onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission [1, 2] orbiting the Moon since 10/6/2013. LDEX is an impact detector, capable of reliably detecting and measuring the mass of submicron and micron sized dust grains. LDEX also measures the collective currents from low-energy ions and from the impacts of dust grains that are below the detection threshold for single dust impacts; hence it can search for the putative population of grains with radii ~ 0.1 μm lofted over the terminator regions by plasma effects. This talk will summarize the preliminary analysis of the observations to date: 1) LDEX identified the dust ejecta cloud that is maintained by micrometeoroid bombardment. As predicted, the density of the dust ejecta cloud rapidly increases toward the surface, and it also shows strong temporal variability, most likely related to the stochastic nature of the meteoroid impacts. 2) LDEX, as of yet, has not confirmed the existence of levitated dust clouds. This puts strict new upper limits on the density of small lofted grains, especially during periods of low ion fluxes entering the instrument. [1] Elphic et al., Proc. Lunar. Sci. Conf. 44th, 1719 (2013) [2] Horanyi et al., Proc. Lunar. Sci. Conf. 43th, 1659 (2012).

  18. Intact capture of cosmic dust

    NASA Technical Reports Server (NTRS)

    Tsou, P.

    1991-01-01

    The focus of this development effort is to capture dust particles at hypervelocities intact and unmelted in order to preserve volatile organics. At the same time, the capture process must minimize any organic elemental or compound contamination to prevent any compromise of exobiological analyses. Inorganic silicate aerogel has been developed as a successful capture medium to satisfy both requirements of intact capture and minimal organic contamination. Up to 6 km/s, silicate projectiles from a few microns up to 100 microns have been captured intact without any melting and with minimal loss of mass. Carbon in silicate aerogel can be reduced to less than 1 part in 1000 and hydrogen 3 parts in 1000 when baked in air. Under controlled inert gas environments, additional hydrocarbon reduction can be achieved.

  19. Cathode Ion Bombardment in RF Photoguns

    SciTech Connect

    Pozdeyev,E.; Kayran, D.; Litvinenko, V.

    2008-09-01

    In this paper, we use the method of rapid oscillating field to solve the equation of ion motion in an RF gun. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper proposes a simple mitigation recipe that can reduce the rate of ion bombardment.

  20. Calibration of impact ionization dust detectors with porous or fluffy dust particles

    NASA Astrophysics Data System (ADS)

    Sterken, V. J.; Moragas-Klostermeyer, G.; Hillier, J. K.; Bugiel, S.; Srama, R.; Armes, S. P.; Fielding; L. A.; Lovett, J. R.; Grün, E.

    2013-07-01

    Impact ionization instruments like the ones flying on Cassini, Galileo, Helios and Ulysses have been calibrated using compact particles made of conductive materials like iron, or of minerals (like Olivine, Orthopyroxene, Magnetite, Pyrite) coated with a thin layer of conductive material. These calibrations were performed by shooting cosmic dust analogues with hypervelocity speeds from 1 to 80 km/s onto the flight spares of these instruments, using the Van de Graaff dust accelerator facility in Heidelberg. Here, we perform first measurements with Cassini CDA of the influence of the density of these dust particles on the resulting signal by, for a given impact speed, comparing signals from micron-sized particles made of compact PPy-coated silica to those from (PPy-coated) hollow silica spheres. The degree of impact ionization depends on the ratio of the densities of the target material and the impactor material and hence, different signals may result from impacts with diffe! rent density or porosity.

  1. 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.

  2. 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.

  3. Optimum Structure of Whipple Shield against Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

    Lee, Minhyung

    2013-06-01

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

  4. Spacecraft outer thermal blankets as hypervelocity impact bumpers

    NASA Astrophysics Data System (ADS)

    Cour-Palais, B. G.

    1996-05-01

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

  5. 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.

  6. Hypervelocity supersonic nozzle beam source of atomic oxygen

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  9. Hypervelocity impact simulation for micrometeorite and debris shield design

    NASA Technical Reports Server (NTRS)

    Fahrenthold, Eric P.

    1992-01-01

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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Ion Bombardment Experiments Suggesting an Origin for Organic Particles in Pre-Cometary and Cometary Ices

    NASA Technical Reports Server (NTRS)

    Wdowiak, Thomas J.; Robinson, Edward L.; Flickinger, Gregory C.; Boyd, David A.

    1997-01-01

    Simple molecules frozen as mantles of interstellar and circumstellar grains and incorporated into comets are subjected to ion bombardment in the form of cosmic rays, stellar flares, stellar winds, and ions accelerated in stellar wind shocks. The total expected dosage for the variety of situations range from 10 eV/molecule for interplanetary dust subjected to solar flares to 10(exp 6) eV/molecule for material in the T Tauri environment. Utilizing a Van de Graaff accelerator and a target chamber having cryogenic and mass spectrometer capabilities, we have bombarded frozen gases in the temperature range of 10 K to 30 K with 175 keV protons. After irradiation, removal of the ice by sublimation at an elevated temperature in vacuum reveals a fluffy residue. These experiments suggest that processes resulting in the formation of organic particles found in the coma of Comet Halley, "CHON", may have included ion bombardment. Also, the moderate energy (100 keV to 500 keV) shock accelerated ion environment of bipolar outflow of stars in the planetary nebula stage such as the Red Rectangle, could produce complex molecular species which emit the observed unidentified infrared bands at 3.3 micro-m, 6.2 micro-m, 7.7 micro-m, 8.6 micro-m, and 11.3 micro-m.

  16. Mass spectra of organic and inorganic dust particles measured by an impact ionization mass analyzer instrument

    NASA Astrophysics Data System (ADS)

    Salter, J. G.; Sternovsky, Z.; Srama, R.; Postberg, F.; Kempf, S.; Armes, S. P.; Gruen, E.; Horanyi, M.; Drake, K.; Westphal, A.

    2009-12-01

    The composition of individual cosmic dust particles can be measured in-situ using existing techniques and instrumentations. The dust particle impacting on a solid surface with hypervelocity (> 1 km/s) is vaporized and partially ionized. The generated ions are extracted and analyzed using time-of-flight methods. Laboratory calibration measurements are possible at the dust accelerator facility in Heidelberg, Germany. The accelerator is limited to using conductive dust that was limited in the past to Fe, Al or graphite samples. In the recent years, however, dust samples of organic materials and inorganic minerals of cosmic interest were developed that are suitable for application in the accelerator. This is achieved by coating micron and submicron sized dust particles by conductive polymers. Here we present the comparison of spectra measured using organic and inorganic dust samples (polystyrene, poly-[bis(4-vinylthiophenyl)sulphide], Phyrotite). The particles were accelerated to speeds between 3 and 35 km/s. 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 Daltons. Clusters resulting from the target material (silver) and mixed clusters of target and projectile species were also observed. 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.

  17. Dust Detector

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.

    2001-01-01

    We discuss a recent sounding rocket experiment which found charged dust in the Earth's tropical mesosphere. The dust detector was designed to measure small (5000 - 10000 amu.) charged dust particles, most likely of meteoric origin. A 5 km thick layer of positively charged dust was found at an altitude of 90 km, in the vicinity of an observed sporadic sodium layer and sporadic E layer. The observed dust was positively charged in the bulk of the dust layer, but was negatively charged near the bottom.

  18. Space science applications for conducting polymer particles: synthetic mimics for cosmic dust and micrometeorites.

    PubMed

    Fielding, Lee A; Hillier, Jon K; Burchell, Mark J; Armes, Steven P

    2015-12-11

    Over the last decade or so, a range of polypyrrole-based particles have been designed and evaluated for space science applications. This electrically conductive polymer enables such particles to efficiently acquire surface charge, which in turn allows their acceleration up to the hypervelocity regime (>1 km s(-1)) using a Van de Graaff accelerator. Either organic latex (e.g. polystyrene or poly(methyl methacrylate)) or various inorganic materials (such as silica, olivine or pyrrhotite) can be coated with polypyrrole; these core-shell particles are useful mimics for understanding the hypervelocity impact ionisation behaviour of micro-meteorites (a.k.a. cosmic dust). Impacts on metal targets at relatively low hypervelocities (<10 km s(-1)) generate ionic plasma composed mainly of molecular fragments, whereas higher hypervelocities (>10 km s(-1)) generate predominately atomic species, since many more chemical bonds are cleaved if the particles impinge with higher kinetic energy. Such fundamental studies are relevant to the calibration of the cosmic dust analyser (CDA) onboard the Cassini spacecraft, which was designed to determine the chemical composition of Saturn's dust rings. Inspired by volcanism observed for one of the Jupiter's moons (Io), polypyrrole-coated sulfur-rich latexes have also been designed to help space scientists understand ionisation spectra originating from sulfur-rich dust particles. Finally, relatively large (20 μm diameter) polypyrrole-coated polystyrene latexes have proven to be useful for understanding the extent of thermal ablation of organic projectiles when fired at ultralow density aerogel targets at up to 6.1 km s(-1) using a Light Gas Gun. In this case, the sacrificial polypyrrole overlayer simply provides a sensitive spectroscopic signature (rather than a conductive overlayer), and the scientific findings have important implications for the detection of organic dust grains during the Stardust space mission. PMID:26458233

  19. Measuring the internal energies of species emitted from hypervelocity nanoprojectile impacts on surfaces using recalibrated benzylpyridinium probe ions

    NASA Astrophysics Data System (ADS)

    DeBord, J. Daniel; Verkhoturov, Stanislav V.; Perez, Lisa M.; North, Simon W.; Hall, Michael B.; Schweikert, Emile A.

    2013-06-01

    We present herein a framework for measuring the internal energy distributions of vibrationally excited molecular ions emitted from hypervelocity nanoprojectile impacts on organic surfaces. The experimental portion of this framework is based on the measurement of lifetime distributions of "thermometer" benzylpyridinium ions dissociated within a time of flight mass spectrometer. The theoretical component comprises re-evaluation of the fragmentation energetics of benzylpyridinium ions at the coupled-cluster singles and doubles with perturbative triples level. Vibrational frequencies for the ground and transition states of select molecules are reported, allowing for a full description of vibrational excitations of these molecules via Rice-Ramsperger-Kassel-Marcus unimolecular fragmentation theory. Ultimately, this approach is used to evaluate the internal energy distributions from the measured lifetime distributions. The average internal energies of benzylpyridinium ions measured from 440 keV Au400+4 impacts are found to be relatively low (˜0.24 eV/atom) when compared with keV atomic bombardment of surfaces (1-2 eV/atom).

  20. Callisto: A lunar-like bombardment?

    NASA Technical Reports Server (NTRS)

    Ruzicka, A.

    1984-01-01

    Voyager spacecraft imagery of the Galilean satellites in 1979 revealed Callisto and portions of Ganymede to be densely cratered, but nonetheless deficient in craters larger than 30 km relative to the cratered highlands of the Moon, Mars, and Mercury. This relative deficiency of large craters could have been due to the complete obliteration of large craters through viscous relaxation in the icy surfaces of Ganymede and Callisto at a time when their surfaces were presumably warmer and more mobile or the deficiency could have stemmed from a relative depletion of large impacting bodies in the Jupiter system, compared with the terrestial planets. To test which alternative is correct, and, specifically, to see whether Callisto was subjected to a lunar-like bombardment, two areas on the heavily cratered lunar farside were compared with an area on Callisto. It was concluded that the Moon and Callisto must have bombarded by two different populations and though viscous relaxation could have modified, or even completely obliterated, craters on Callisto's surface, it could not hve been solely responsible for the observed deficiency of large craters on Callisto relative to the moon.

  1. Energetic ion bombarded Fe/Al multilayers

    SciTech Connect

    Al-Busaidy, M.S.; Crapper, M.D.

    2006-05-15

    The utility of ion-assisted deposition is investigated to explore the possibility of counteracting the deficiency of back-reflected current of Ar neutrals in the case of lighter elements such as Al. A range of energetically ion bombarded Fe/Al multilayers sputtered with applied surface bias of 0, -200, or -400 V were deposited onto Si(111) substrates in an argon atmosphere of 4 mTorr using a computer controlled dc magnetron sputtering system. Grazing incidence reflectivity and rocking curve scans by synchrotron x rays of wavelength of 1.38 A were used to investigate the structures of the interfaces produced. Substantial evidence has been gathered to suggest the gradual suppression of interfacial mixing and reduction in interfacial roughness with increases of applied bias. The densification of the Al microstructure was noticeable and may be a consequence of resputtering attributable to the induced ion bombardment. The average interfacial roughnesses were calculated for the 0, -200, and -400 V samples to be 7{+-}0.5, 6{+-}0.5, and 5{+-}0.5 A respectfully demonstrating a 30% improvement in interface quality. Data from rocking curve scans point to improved long-range correlated roughness in energetically deposited samples. The computational code based on the recursive algorithm developed by Parratt [Phys. Rev. 95, 359 (1954)] was successful in the simulation of the specular reflectivity curves.

  2. Wandering Gas Giants and Lunar Bombardment

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2006-08-01

    There may have been a dramatic event early in the history of the Solar System--the intense bombardment of the inner planets and the Moon by planetesimals during a narrow interval between 3.92 and 3.85 billion years ago, called the late heavy bombardment, but also nicknamed the lunar cataclysm. The evidence for this event comes from Apollo lunar samples and lunar meteorites. While not proven, it makes for an interesting working hypothesis. If correct, what caused it to happen? A group of physicists from the Observatoire de la Côte d'Azur (Nice, France), GEA/OV/Universidade Federal do Rio de Janeiro and Observatorio Nacional/MTC (Rio de Janeiro, Brazil), and the Southwest Research Institute (Boulder, Colorado) conducted a series of studies of the dynamics of the early Solar System. Alessandro Morbidelli, Kleomenis Tsiganis, Rodney Gomes, and Harold Levison simulated the migration of Saturn and Jupiter. When the orbits of these giant planets reached the special condition of Saturn making one trip around the Sun for every two trips by Jupiter (called the 1:2 resonance), violent gravitational shoves made the orbits of Neptune and Uranus unstable, causing them to migrate rapidly and scatter countless planetesimals throughout the Solar System. This dramatic event could have happened in a short interval, anywhere from 200 million years to a billion years after planet formation, causing the lunar cataclysm, which would have affected all the inner planets.

  3. Cosmic dust

    NASA Technical Reports Server (NTRS)

    Brownlee, Donald E.; Sandford, Scott A.

    1992-01-01

    Dust is a ubiquitous component of our galaxy and the solar system. The collection and analysis of extraterrestrial dust particles is important to exobiology because it provides information about the sources of biogenically significant elements and compounds that accumulated in distant regions of the solar nebula and that were later accreted on the planets. The topics discussed include the following: general properties of interplanetary dust; the carbonaceous component of interplanetary dust particles; and the presence of an interstellar component.

  4. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    article title:  Massive Dust Storm over Australia     View ... at JPL September 22, 2009 - Massive dust storm over Australia. project:  MISR category:  ... Sep 22, 2009 Images:  Dust Storm location:  Australia and New Zealand ...

  5. Sahara Dust

    Atmospheric Science Data Center

    2013-04-15

    article title:  Casting Light and Shadows on a Saharan Dust Storm     ... (nadir) camera. High-altitude cirrus clouds cast shadows on the underlying ocean and dust layer, which are visible in shades of ... was unable to retrieve elevation data. However, the edges of shadows cast by the cirrus clouds onto the dust (indicated by blue and cyan ...

  6. Circumstellar dust

    NASA Technical Reports Server (NTRS)

    Dwek, E.

    1986-01-01

    The presence of dust in the general interstellar medium is inferred from the extinction, polarization, and scattering of starlight; the presence of dark nebulae; interstellar depletions; the observed infrared emission around certain stars and various types of interstellar clouds. Interstellar grains are subject to various destruction mechanisms that reduce their size or even completely destroy them. A continuous source of newly formed dust must therefore be present for dust to exist in the various phases of the interstellar medium (ISM). The working group has the following goals: (1) review the evidences for the formation of dust in the various sources; (2) examine the clues to the nature and composition of the dust; (3) review the status of grain formation theories; (4) examine any evidence for the processing of the dust prior to its injection into the interstellar medium; and (5) estimate the relative contribution of the various sources to the interstellar dust population.

  7. Bombarding insulating foils with highly energetic ions

    NASA Astrophysics Data System (ADS)

    Lanzanò, G.; de Filippo, E.; Hagmann, S.; Rothard, H.; Volant, C.

    Insulating (MYLAR), semi-insulating (MYLAR-Au) and conducting foils have been bombarded by very energetic 64 MeV u-1 78Kr32+ ions. The velocity spectra of fast electrons emitted in the backward and forward directions have been measured and analyzed as a function of the elapsed time in the run. A shift of binary encounter and convoy electrons emitted in the forward direction toward lower velocities has been observed with insulating targets. No such shift occurs with metallic targets. The surface potential evolves with time (i.e. ion fluence) both at forward and backward emission angle. It is shown that strong bulk charging of insulating targets leads to a positive potential as high as 9 kV before charge breakdown.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Hypervelocity impact damage tolerance of fused silica glass

    NASA Technical Reports Server (NTRS)

    Edelstein, K. S.

    1992-01-01

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

  11. Protoplanetary Dust

    NASA Astrophysics Data System (ADS)

    Apai, Dániel; Lauretta, Dante S.

    2010-01-01

    Preface; 1. Planet formation and protoplanetary dust Daniel Apai and Dante Lauretta; 2. The origins of protoplanetary dust and the formation of accretion disks Hans-Peter Gail and Peter Hope; 3. Evolution of protoplanetary disk structures Fred Ciesla and Cornelius P. Dullemond; 4. Chemical and isotopic evolution of the solar nebula and protoplanetary disks Dmitry Semenov, Subrata Chakraborty and Mark Thiemens; 5. Laboratory studies of simple dust analogs in astrophysical environments John R. Brucato and Joseph A. Nuth III; 6. Dust composition in protoplanetaty dust Michiel Min and George Flynn; 7. Dust particle size evolution Klaus M. Pontoppidan and Adrian J. Brearly; 8. Thermal processing in protoplanetary nebulae Daniel Apai, Harold C. Connolly Jr. and Dante S. Lauretta; 9. The clearing of protoplanetary disks and of the protosolar nebula Ilaira Pascucci and Shogo Tachibana; 10. Accretion of planetesimals and the formation of rocky planets John E. Chambers, David O'Brien and Andrew M. Davis; Appendixes; Glossary; Index.

  12. Protoplanetary Dust

    NASA Astrophysics Data System (ADS)

    Apai, D.´niel; Lauretta, Dante S.

    2014-02-01

    Preface; 1. Planet formation and protoplanetary dust Daniel Apai and Dante Lauretta; 2. The origins of protoplanetary dust and the formation of accretion disks Hans-Peter Gail and Peter Hope; 3. Evolution of protoplanetary disk structures Fred Ciesla and Cornelius P. Dullemond; 4. Chemical and isotopic evolution of the solar nebula and protoplanetary disks Dmitry Semenov, Subrata Chakraborty and Mark Thiemens; 5. Laboratory studies of simple dust analogs in astrophysical environments John R. Brucato and Joseph A. Nuth III; 6. Dust composition in protoplanetaty dust Michiel Min and George Flynn; 7. Dust particle size evolution Klaus M. Pontoppidan and Adrian J. Brearly; 8. Thermal processing in protoplanetary nebulae Daniel Apai, Harold C. Connolly Jr. and Dante S. Lauretta; 9. The clearing of protoplanetary disks and of the protosolar nebula Ilaira Pascucci and Shogo Tachibana; 10. Accretion of planetesimals and the formation of rocky planets John E. Chambers, David O'Brien and Andrew M. Davis; Appendixes; Glossary; Index.

  13. 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

  14. 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.

  15. 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.

  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. PMID:25071234

  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. 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.

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

    SciTech Connect

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

    1988-09-20

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

  20. Optimum structure of Whipple shield against hypervelocity impact

    NASA Astrophysics Data System (ADS)

    Lee, M.

    2014-05-01

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

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

    PubMed

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

    2003-02-01

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

  2. 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.

  3. 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.

  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 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.

  6. Piezoelectric Pins for Use as Dust Detectors

    NASA Astrophysics Data System (ADS)

    Manning, H. L. K.; Campbell, I. H.; Nelson, K. A.; Yager, J. R.

    2002-09-01

    Piezoelectric pins are devices currently used in a number of applications including detecting elementary particle beams, monitoring volcanoes, and detecting high-speed micro-sized particles. These pins provide a means of studying ejecta from cratering processes in the laboratory and offer a potential lightweight, low power, flight dust detector. Using the hypervelocity dust particle accelerator at Concordia College in Moorhead, Minnesota, we have investigated the transient charge generated by piezoelectric pins impacted by dust particles. Carbonyl iron dust particles of 0.5-5 micrometer diameter having speeds ranging from 1-5 km/sec impacted the pins. The DC-100 MHz pin response was recorded and analyzed. The transient pin response to a single particle consists of many charge pulses of alternating sign (less than 10 ns in duration) separated by the pressure wave propagation time across the crystal (typically 100 ns). The charge produced by the pin changes sign when the pressure waves in the piezoelectric crystal reflect off of the metal electrodes. The magnitude of the pin response as a function of the impacting particle properties is presented and discussed. Pins using both polycrystalline PZT and single crystal LiNbO3 as the piezoelectric material were studied. This work is supported at Concordia College by the Minnesota Space Grant Consortium.

  7. In-Situ Dust Detection by Spacecraft Antennas: Laboratory Characterization of Particle Energies and Geometrical Effects

    NASA Astrophysics Data System (ADS)

    Rocha, J. R. R.; Collette, A.; Sternovsky, Z.; Malaspina, D.; Thayer, F.

    2015-12-01

    We describe direct laboratory investigation of signals generated by hypervelocity dust impacts on spacecraft. Although the majority of spacecraft do not carry dedicated dust detectors, those with antenna-based instruments routinely observe impulsive signals from dust impacts on the spacecraft and antennas. Recent analysis of signals from the STEREO spacecraft WAVES electric field sensors, and unexpected high-altitude observations at Mars by MAVEN's LPW instrument, highlight the opportunity for in-situ dust detection by such spacecraft. However, quantitative interpretation of the spacecraft data currently suffers from large uncertainties, including the quantity and energy distribution of charged particles released, the effect of the spacecraft configuration and impact location, and the near-spacecraft electric fields and plasma environment. We report a series of experiments conducted at the IMPACT hypervelocity dust accelerator facility at the University of Colorado Boulder, to investigate (1) the effects of spacecraft and antenna potential on charge recollection and consequent signals, (2) the energy distribution of charged particles produced by dust impacts on realistic spacecraft materials at various speeds, and (3) the influence of spacecraft geometry, using impacts distributed across a high-fidelity model of the STEREO spacecraft. Implications for future spacecraft observations are also discussed.

  8. Analysis of Interplanetary Dust Experiment Detectors and Other Witness Plates

    NASA Technical Reports Server (NTRS)

    Griffis, D. P.; Wortman, J. J.

    1992-01-01

    The development of analytical procedures for identifying the chemical composition of residue from impacts that occurred on the Interplanetary Dust Experiment (IDE) detectors during the flight of Long Duration Exposure Facility (LDEF) and the carrying out of actual analysis on IDE detectors and other witness plates are discussed. Two papers on the following topics are presented: (1) experimental analysis of hypervelocity microparticle impact sites on IDE sensor surfaces; and (2) contaminant interfaces with secondary Ion Mass Spectrometer (SIMS) analysis of microparticle impactor residues on LDEF surfaces.

  9. Some Expected Mechanical Characteristics of Lunar Dust: A Geological View

    NASA Technical Reports Server (NTRS)

    Rickman, Doug; Street, Kenneth W.

    2008-01-01

    The engineering properties of the lunar regolith reflect aspects of the original parent rock and the consequences of hypervelocity meteor bombardment. Compared to the Earth the geologic nature of the lunar regolith is quite distinct. On scales relevant to machinery, heterogeneity with respect to size and composition is much higher. But the total range in composition is much more restricted. Both facts have implications for predictions of properties, such as abrasion, which will be required by design engineers for constructing equipment for lunar use. Abrasion is related to hardness and hardness is a commonly measured property for both minerals and engineering materials. Although different hardness scales are routinely employed for minerals and engineering materials, a significant amount of literature is available relating the two. In this paper we discuss how to relate hardness to abrasion for the design of lunar equipment. We also indicate how abundant the various mineral phases are and typical size distributions for lunar regolith.

  10. Modification of Polymer Materials by Ion Bombardment: Case Studies

    SciTech Connect

    Bielinski, D. M.; Jagielski, J.; Piatkowska, A.

    2009-03-10

    The paper discusses possibility of application of ion beam bombardment for modification of polymers. Changes to composition, structure and morphology of the surface layer produced by the treatment and their influence on engineering and functional properties of wide range of polymer materials are presented. Special attention has been devoted to modification of tribological properties. Ion bombardment results in significant reduction of friction, which can be explained by increase of hardness and wettability of polymer materials. Hard but thin enough skin does not result in cracking but improves their abrasion resistance. Contrary to conventional chemical treatment ion beam bombardment works even for polymers hardly susceptible to modification like silicone rubber or polyolefines.

  11. Modification of Polymer Materials by Ion Bombardment: Case Studies

    NASA Astrophysics Data System (ADS)

    Bielinski, D. M.; Jagielski, J.; Lipinski, P.; Pieczynska, D.; Ostaszewska, U.; Piatkowska, A.

    2009-03-01

    The paper discusses possibility of application of ion beam bombardment for modification of polymers. Changes to composition, structure and morphology of the surface layer produced by the treatment and their influence on engineering and functional properties of wide range of polymer materials are presented. Special attention has been devoted to modification of tribological properties. Ion bombardment results in significant reduction of friction, which can be explained by increase of hardness and wettability of polymer materials. Hard but thin enough skin does not result in cracking but improves their abrasion resistance. Contrary to conventional chemical treatment ion beam bombardment works even for polymers hardly susceptible to modification like silicone rubber or polyolefines.

  12. Dust Storm

    Atmospheric Science Data Center

    2013-04-16

    ... contrast strongly with the dust storm that swept across Iraq and Saudi Arabia on May 13, 2004 (bottom panels). These data products from ... as yellowish ripples that obscure a large part of southern Iraq. The dust is easy to discern over the dark waters of the teardrop-shaped ...

  13. Hydrogen diffusion in steels under electron bombardment

    NASA Astrophysics Data System (ADS)

    Larionov, V. V.; Nikitenkov, N. N.; Tyurin, Yu. I.

    2016-05-01

    We report on the results of measurement of the coefficients of hydrogen diffusion through metal membranes in the course of their simultaneous hydrogen saturation and bombardment with electrons (energy 30 keV, current density from 3 to 30 µA/cm2) both in a broad and in a narrow beam. It is found that the time of hydrogen discharge from the membrane is determined by the parameters of the electron beam, its periodicity and duration, and also depends on the structure of the phase state of the metal membrane. It is shown that the diffusion coefficient increases when a narrow electron beam in the scanning regime is used. Analysis of the hydrogen yield as a function of time is carried out on a mass spectrometer connected to a vacuum chamber containing an electron gun, a beam sweep oscillator, and an electrolytic cell. The hydrogen diffusion coefficients under the action of a scanning electron beam are 15 times larger than under the same conditions without irradiation.

  14. Genetic transformation of wheat via particle bombardment.

    PubMed

    Sparks, Caroline A; Jones, Huw D

    2014-01-01

    Since its first invention in the late 1980s the particle gun has evolved from a basic gunpowder driven machine firing tungsten particles to one more refined which uses helium gas as the propellant to launch alternative heavy metal particles such as gold and silver. The simple principle is that DNA-coated microscopic particles (microcarriers) are accelerated at high speed by helium gas within a vacuum and travel at such a velocity as to penetrate target cells. However, the process itself involves a range of parameters which are open to variation: microparticle type and size, gun settings (rupture pressure, target distance, vacuum drawn, etc.), preparation of components (e.g., gold coating), and preparation of plant tissues. Here is presented a method optimized for transformation of wheat immature embryos using the Bio-Rad PDS-1000/He particle gun to deliver gold particles coated with a gene of interest and the selectable marker gene bar at 650 psi rupture pressure. Following bombardment, various tissue culture phases are used to encourage embryogenic callus formation and regeneration of plantlets and subsequent selection using glufosinate ammonium causes suppression of non-transformed tissues, thus assisting the detection of transformed plants. This protocol has been used successfully to generate transgenic plants for a wide range of wheat varieties, both spring and winter bread wheats (T. aestivum L.) and durum wheats (T. turgidum L.). PMID:24243206

  15. Andromeda's dust

    SciTech Connect

    Draine, B. T.; Aniano, G.; Krause, Oliver; Groves, Brent; Sandstrom, Karin; Klaas, Ulrich; Linz, Hendrik; Rix, Hans-Walter; Schinnerer, Eva; Schmiedeke, Anika; Walter, Fabian; Braun, Robert; Leroy, Adam E-mail: ganiano@ias.u-psud.fr

    2014-01-10

    Spitzer Space Telescope and Herschel Space Observatory imaging of M31 is used, with a physical dust model, to construct maps of dust surface density, dust-to-gas ratio, starlight heating intensity, and polycyclic aromatic hydrocarbon (PAH) abundance, out to R ≈ 25 kpc. The global dust mass is M {sub d} = 5.4 × 10{sup 7} M {sub ☉}, the global dust/H mass ratio is M {sub d}/M {sub H} = 0.0081, and the global PAH abundance is (q {sub PAH}) = 0.039. The dust surface density has an inner ring at R = 5.6 kpc, a maximum at R = 11.2 kpc, and an outer ring at R ≈ 15.1 kpc. The dust/gas ratio varies from M {sub d}/M {sub H} ≈ 0.026 at the center to ∼0.0027 at R ≈ 25 kpc. From the dust/gas ratio, we estimate the interstellar medium metallicity to vary by a factor ∼10, from Z/Z {sub ☉} ≈ 3 at R = 0 to ∼0.3 at R = 25 kpc. The dust heating rate parameter (U) peaks at the center, with (U) ≈ 35, declining to (U) ≈ 0.25 at R = 20 kpc. Within the central kiloparsec, the starlight heating intensity inferred from the dust modeling is close to what is estimated from the stars in the bulge. The PAH abundance reaches a peak q {sub PAH} ≈ 0.045 at R ≈ 11.2 kpc. When allowance is made for the different spectrum of the bulge stars, q {sub PAH} for the dust in the central kiloparsec is similar to the overall value of q {sub PAH} in the disk. The silicate-graphite-PAH dust model used here is generally able to reproduce the observed dust spectral energy distribution across M31, but overpredicts 500 μm emission at R ≈ 2-6 kpc, suggesting that at R = 2-6 kpc, the dust opacity varies more steeply with frequency (with β ≈ 2.3 between 200 and 600 μm) than in the model.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Kimberley, J.; Ramesh, K. T.

    2012-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  1. Dynamic behavior of thermionic dispenser cathodes under ion bombardment

    NASA Astrophysics Data System (ADS)

    Cortenraad, R.; van der Gon, A. W. Denier; Brongersma, H. H.; Gärtner, G.; Raasch, D.; Manenschijn, A.

    2001-04-01

    We have investigated the surface coverage and electron emission of thermionic dispenser cathodes during 3 keV Ar+ ion bombardment, thereby simulating the bombardment of the cathodes by residual gases that takes place in cathode-ray tubes as used in television sets. During the ion bombardment at the operating temperature of 1030 °C, a dynamic equilibrium is established between the sputter removal and resupply mechanisms of the Ba and O atoms that form the dipole layer on the cathode substrate. We demonstrated that the performance of the cathodes under ion bombardment is governed by the O removal and resupply rates. It was found that the Ba resupply rate is almost an order of magnitude higher than the O resupply rate, but that the Ba can only be present on the surface bound to O atoms. Therefore, the Ba/O ratio is approximately equal to unity during the ion bombardment. Based on the investigations of the removal and resupply processes, we proposed a model that accurately describes the surface coverage and electron emission during the ion bombardment, including the dependence of the ion flux and cathode temperature.

  2. 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.

  3. 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.

  4. 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.

  5. Experimental Study of Spacecraft Material Ejected upon Hypervelocity Impact

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  6. 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.

  7. Effects of oblique impact on hypervelocity shield performance

    SciTech Connect

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

    1990-01-01

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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Multi-Dimensional Hydrocode Analyses of Penetrating Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

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

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

    SciTech Connect

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

    2003-08-01

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

  14. A SELF-CONSISTENT MODEL OF THE CIRCUMSTELLAR DEBRIS CREATED BY A GIANT HYPERVELOCITY IMPACT IN THE HD 172555 SYSTEM

    SciTech Connect

    Johnson, B. C.; Melosh, H. J.; Lisse, C. M.; Chen, C. H.; Wyatt, M. C.; Thebault, P.; Henning, W. G.; Gaidos, E.; Elkins-Tanton, L. T.; Bridges, J. C.; Morlok, A.

    2012-12-10

    Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 10{sup 19} kg of submicron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at {approx}6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the debris disk in less than one year. However, the system's mid-infrared photometric flux, dominated by submicron grains, has been stable within 4% over the last 27 years, from the Infrared Astronomical Satellite (1983) to WISE (2010). Our new spectral modeling work and calculations of the radiation pressure on fine dust in HD 172555 provide a self-consistent explanation for this apparent contradiction. We also explore the unconfirmed claim that {approx}10{sup 47} molecules of SiO vapor are needed to explain an emission feature at {approx}8 {mu}m in the Spitzer IRS spectrum of HD 172555. We find that unless there are {approx}10{sup 48} atoms or 0.05 M{sub Circled-Plus} of atomic Si and O vapor in the system, SiO vapor should be destroyed by photo-dissociation in less than 0.2 years. We argue that a second plausible explanation for the {approx}8 {mu}m feature can be emission from solid SiO, which naturally occurs in submicron silicate ''smokes'' created by quickly condensing vaporized silicate.

  15. A Self-consistent Model of the Circumstellar Debris Created by a Giant Hypervelocity Impact in the HD 172555 System

    NASA Astrophysics Data System (ADS)

    Johnson, B. C.; Lisse, C. M.; Chen, C. H.; Melosh, H. J.; Wyatt, M. C.; Thebault, P.; Henning, W. G.; Gaidos, E.; Elkins-Tanton, L. T.; Bridges, J. C.; Morlok, A.

    2012-12-01

    Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 1019 kg of submicron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at ~6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the debris disk in less than one year. However, the system's mid-infrared photometric flux, dominated by submicron grains, has been stable within 4% over the last 27 years, from the Infrared Astronomical Satellite (1983) to WISE (2010). Our new spectral modeling work and calculations of the radiation pressure on fine dust in HD 172555 provide a self-consistent explanation for this apparent contradiction. We also explore the unconfirmed claim that ~1047 molecules of SiO vapor are needed to explain an emission feature at ~8 μm in the Spitzer IRS spectrum of HD 172555. We find that unless there are ~1048 atoms or 0.05 M ⊕ of atomic Si and O vapor in the system, SiO vapor should be destroyed by photo-dissociation in less than 0.2 years. We argue that a second plausible explanation for the ~8 μm feature can be emission from solid SiO, which naturally occurs in submicron silicate "smokes" created by quickly condensing vaporized silicate.

  16. Bombardment-induced segregation and redistribution

    SciTech Connect

    Lam, N.Q.; Wiedersich, H.

    1986-04-01

    During ion bombardment, a number of processes can alter the compositional distribution and microstructure in near-surface regions of alloys. The relative importance of each process depends principally on the target composition, temperature, and ion characteristics. In addition to displacement mixing leading to a randomization of atomic locations, and preferential loss of alloying elements by sputtering, which are dominant at relatively low temperatures, several thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. At elevated temperatures, nonequilibrium point defects induced by ion impacts become mobile and tend to anneal out by recombination and diffusion to extended sinks, such as dislocations, grain boundaries and free surfaces. The high defect concentrations, far exceeding the thermodynamic equilbrium values, can enhance diffusion-controlled processes, while persistent defect fluxes, originating from the spatial non-uniformity in defect production and annihilation, give rise to local redistribution of alloy constituents because of radiation-induced segregation. Moreover, when the alloy is maintained at high temperature, Gibbsian adsorption, driven by the reduction in free energy of the system, occurs even without irradiation; it involves a compositional perturbation in a few atom layers near the alloy surface. The combination of these processes leads to the complex development of a compositionally-modified layer in the subsurface region. In the present paper, selected examples of these different phenomena and their synergistic effects on the evolution of the near-surface compositions of alloys during sputtering and ion implantation at elevated temperatures are discussed. 74 refs., 7 figs., 1 tab.

  17. Dust particle injector for hypervelocity accelerators provides high charge-to-mass ratio

    NASA Technical Reports Server (NTRS)

    Berg, O. E.

    1966-01-01

    Injector imparts a high charge-to-mass ratio to microparticles and injects them into an electrostatic accelerator so that the particles are accelerated to meteoric speeds. It employs relatively large masses in the anode and cathode structures with a relatively wide separation, thus permitting a large increase in the allowable injection voltages.

  18. Laboratory Study of Titan's Surface Chemistry Induced by Meteoritic Impact Processing: Laser-Simulated Hypervelocity Impact on Ices

    NASA Astrophysics Data System (ADS)

    Nna-Mvondo, D.; Khare, B. N.; McKay, C. P.

    2008-12-01

    Titan's dense atmosphere, mostly composed of nitrogen and some methane, allows easy formation of long chains of organic molecules and high-molecular-weight organic solids, known as tholins. Over geologic time, both tholins and condensates of the organic gases accumulate in substantial amounts on the surface as liquid and solid. Titan's surface is then a repository of interesting organic molecules generated in the almost complete absence of water but sitting on top of ice. Until recently, researchers have been very careful in their speculations about what might be happening after these molecules get to the surface of Titan. What kind of organic chemistry occurs on the surface? Titan's thick atmosphere protects the surface and organics from harmful cosmic rays and ultraviolet radiation. It has been suggested that these organics could have been subjected to impact processing on Titan's and participate in the formation of products relevant to life such as amino acids, carboxylic acids, purines and pyrimidines. Subsequent impacts would probably have recycled some of the organic material back into the atmosphere. Furthermore the presence of condensable agents (C2N2, HCN, etc.) along with a natural concentrating mechanism makes polymerization of amino acids or others species likely. Laboratory simulations of meteoritic impact shocks onto Titan's icy surface have not yet been carried out, but preliminary experiments have been performed for planetary icy satellites. In these previous experiments, the possible chemical production induced by micrometeorite impact shocks on ices has been studied using a high-energy pulsed Nd-YAG laser to reproduce the shock phenomena during hypervelocity micrometeorite impacts into the icy material. The results show the production of various organics and inorganics. Here we have decided to extend those experiments to a simulated Titan's environment in order to study the effect of meteoritic impacts on the organic chemistry occurring on Titan

  19. Exozodiacal dust

    NASA Astrophysics Data System (ADS)

    Kuchner, Marc Jason

    Besides the sun, the most luminous feature of the solar system is a cloud of "zodiacal" dust released by asteroids and comets that pervades the region interior to the asteroid belt. Similar clouds of dust around other stars---exozodiacal clouds---may be the best tracers of the habitable zones of extra-solar planetary systems. This thesis discusses three searches for exozodiacal dust: (1) We observed six nearby main-sequence stars with the Keck telescope at 11.6 microns, correcting for atmosphere-induced wavefront aberrations and deconvolving the point spread function via classical speckle analysis. We compare our data to a simple model of the zodiacal dust in our own system based on COBE DIRBE observations and place upper limits on the density of exozodiacal dust in these systems. (2) We observed Sirius, Altair, and Procyon with the NICMOS Coronagraph on the Hubble Space Telescope to look for scattered light from exozodiacal dust and faint companions within 10 AU from these stars. (3) The planned nulling capability of the Keck Interferometer should allow it to probe the region <200 milliarcsecond from a bright star and to suppress on-axis starlight by factors of 10 -3 to reveal faint circumstellar material. We model the response of the Keck Interferometer to hypothetical exozodiacal clouds to derive detection limits that account for the effects of stellar leakage, photon noise, noise from null depth fluctuations, and the fact that the cloud's shape is not known a priori. We also discuss the interaction of dust with planets. We used the COBE DIRBE Sky and Zodi Atlas and the IRAS Sky Survey Atlas to search for dynamical signatures of three different planets in the solar system dust complex: (1) We searched the COBE DIRBE Sky and Zodi Atlas for a wake of dust trailing Mars. We compare the DIRBE images to a model Mars wake based on the empirical model of the Earth's wake as seen by the DIRBE. (2) We searched the COBE DIRRE Sky and Zodi Atlas for Tiojan dust near

  20. New Evidence from Silica Debris Exo-Systems for Planet Building Hypervelocity Impacts

    NASA Astrophysics Data System (ADS)

    Lisse, Carey

    2010-05-01

    There is abundant inferential evidence for massive collisions in the early solar system [1]: Mercury's high density; Venus' retrograde spin; Earth's Moon; Mars' North/South hemispherical cratering anisotropy; Vesta's igneous origin [2]; brecciation in meteorites [3]; and Uranus' spin axis located near the plane of the ecliptic. Recent work [4] analyzing Spitzer mid-IR spectra has demonstrated the presence of large amounts of amorphous silica and SiO gas produced by a recent (within 103 - 104 yrs) large (MExcess > MPluto) hypervelocity impact collision around the young (~12 Myr old) nearby star HD172555, at the right age to form rocky planets. Many questions still remain concerning the location, lifetime, and source of the detected silica/SiO gas, which should not be stable in orbit at the estimated 5.8 AU from the HD172555 A5V primary for more than a few decades, yet it is also highly unlikely that we are fortuitously observing these systems immediately after silica formation A tabulation of the amount counts in the fine silica dust is decidedly Fe and Mg-atom poor compared to solar [4]. Three possible origins for the observed silica/SiO gas seem currently plausible : (1) A single hyperevelocity impact (>10km/s in order to produce silica and vaporize SiO at impact) creating an optically thick circumplanetary debris ring which is overflowing or releasing silica-rich material from its Hill sphere. Like terrestrial tektites, the Fe/Mg poor amorphous silica rubble is formed from quick-quenched molten/vaporized rock created during the impact. The amount of dust detected in the HD172555 system is easily enough to fill and overflow the Hill sphere radius of 0.03 AU for a Pluto-sized body at 5.8 AU from an A5 star, unless it is optically thick (> 1 cm in physical depth). Such a disk would provide a substantial fraction of the observed IR flux, and will be dense enough to self-shield its SiO gas, greatly extending its photolytic lifetime. The lifetime for such a system

  1. Summary of the results from the Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment (LADEE) Mission

    NASA Astrophysics Data System (ADS)

    Horanyi, Mihaly

    2016-07-01

    The Lunar Dust Experiment (LDEX) onboard the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission (9/2013 - 4/2014) discovered a permanently present dust cloud engulfing the Moon. The size, velocity, and density distributions of the dust particles are consistent with ejecta clouds generated from the continual bombardment of the lunar surface by sporadic interplanetary dust particles. Intermittent density enhancements were observed during several of the annual meteoroid streams, especially during the Geminids. LDEX found no evidence of the expected density enhancements over the terminators where electrostatic processes were predicted to efficiently loft small grains. LDEX is an impact ionization dust detector, it captures coincident signals and full waveforms to reliably identify dust impacts. LDEX recorded average impact rates of approximately 1 and 0.1 hits/minute of particles with impact charges of q > 0.5 and q > 5 fC, corresponding to particles with radii of a > 0.3 and a> 0.7~μm, respectively. Several of the yearly meteor showers generated sustained elevated levels of impact rates, especially if their radiant direction intersected the lunar surface near the equatorial plane, greatly enhancing the probability of crossing their ejecta plumes. The characteristic velocities of dust particles in the cloud are on the order of ~100 m/s which we neglect compared to the typical spacecraft speeds of 1.6 km/s. Hence, with the knowledge of the spacecraft orbit and attitude, impact rates can be directly turned into particle densities as functions of time and position. LDEX observations are the first to identify the ejecta clouds around the Moon sustained by the continual bombardment of interplanetary dust particles. Most of the dust particles generated in impacts have insufficient energy to escape and follow ballistic orbits, returning to the surface, 'gardening' the regolith. Similar ejecta clouds are expected to engulf all airless planetary objects, including

  2. 2-DUST: Dust radiative transfer code

    NASA Astrophysics Data System (ADS)

    Ueta, Toshiya; Meixner, Margaret

    2016-04-01

    2-DUST is a general-purpose dust radiative transfer code for an axisymmetric system that reveals the global energetics of dust grains in the shell and the 2-D projected morphologies of the shell that are strongly dependent on the mixed effects of the axisymmetric dust distribution and inclination angle. It can be used to model a variety of axisymmetric astronomical dust systems.

  3. PERSPECTIVE: Dust, fertilization and sources

    NASA Astrophysics Data System (ADS)

    Remer, Lorraine A.

    2006-11-01

    fraction that arrives at another continent [2]. At the deposition end of the chain, it is still unclear how the limited minerals in the dust such as iron are released for uptake by organisms either on land or in the ocean. Not all dust deposited into oceans results in a phytoplankton bloom. The process requires a chemical pathway that mobilizes a fraction of the iron into soluble form. Meskhidze et al [3] show that phytoplankton blooms following dust transport from the Gobi desert in Asia into the Pacific ocean result in a phytoplankton bloom only if the dust is accompanied by high initial SO2-to-dust ratios, suggesting that sulfuric acid coatings on the dust particle mobilize the embedded iron in the dust for phytoplankton uptake. Quantifying transport, deposition and nutrient availability are the latter ends of a puzzle that must begin by identifying and quantifying dust emission at the sources. The emission process is complex at the microscale requiring the right conditions for saltation and bombardment, which makes identification and inclusion of sources in global transport models very difficult. The result is that estimates of annual global dust emissions range from 1000 to 3000 Tg per year [4]. Even as global estimates of dust emissions are uncertain, localizing the sources brings even greater uncertainty. It has been recognized for several years that dust sources are not uniformly distributed over the arid regions of the Earth, but are regulated to topographic lows associated with dried lake deposits [5]. Using aerosol information from satellites, a comprehensive map of the world's source regions shows sources localized to specific areas of the Earth's arid regions [6]. Still these maps suggest broad emission sources covering several degrees of latitude and longitude. In the paper by Koren and co-authors [7] appearing in this issue, one particular dust source, the Bodélé depression in Chad, is analyzed in detail. They find that the specific topography of the

  4. Dust in the Jovian System: Streams, Clouds and Rings

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Gruen, E.

    2003-04-01

    Spacecraft investigations during the last ten years have vastly improved our knowledge about dust in the Jovian system. All Galilean satellites, and probably all smaller satellites as well, are sources of dust in the Jovian system. In-situ measurements with the dust detectors on board the Ulysses and Galileo spacecraft have for the first time demonstrated the electromagnetic interaction of charged dust grains with the interplanetary magnetic field and with a planetary magnetosphere. Jupiter's magnetosphere acts as a giant mass-velocity spectrometer for charged 10-nanometer dust grains. These grains are released from Jupiter's moon Io with a typical rate of ˜ 1 kg s-1. The seven-year long record of Galileo in-situ dust measurements revealed significant variations of the fluxes of the dust stream particles with Jovian local time which are caused by the dawn-dusk asymmetry of the Io plasma torus. The streams probe the plasma conditions in the torus, and they can be used as a potential monitor of Io's volcanic plume activity. The joint Galileo-Cassini dust measurements at Jupiter imply stream particle speeds up to 400 km s-1. All Galilean satellites are surrounded by tenuous impact-generated clouds of mostly sub-micrometer ejecta grains. Jovian rings not only exist in the well-known region of the main and gossamer rings but also much farther out. Very tenuous rings composed of mostly micron-sized grains have been detected in-situ in the region between the Galilean moons and further beyond out to ˜ 250 R_J from the planet. The dust densities there are much too low to allow detection with imaging techniques. The measurements have demonstrated that impact-ejecta derived from hypervelocity impacts onto satellites are the major constituent of dusty planetary rings. On 5 November 2002 Galileo traversed Jupiter's gossamer rings for the first time and had a close flyby at Amalthea. Several hundred dust impacts have been detected during this passage with the dust detector on

  5. 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.

  6. 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.

  7. Understanding 1D Electrostatic Dust Levitation

    NASA Astrophysics Data System (ADS)

    Hartzell, C. M.; Scheeres, D. J.

    2011-12-01

    Electrostatically-dominated dust motion has been hypothesized since the Lunar Horizon Glow was observed by the Surveyor spacecraft. The hypothesized occurence of this phenomenon was naturally extended to asteroids due to their small gravities. Additionally, it has been suggested that the dust ponds observed on Eros by the NEAR mission may be created by electrostatically-dominated dust transport. Previous attempts to numerically model dust motion on the Moon and Eros have been stymied by poorly understood dust launching mechanisms. As a result, the initial velocity and charge of dust particles used in numerical simulations may or may not have any relevance to the actual conditions occurring in situ. It has been seen that properly tuned initial states (velocity and charge) result in dust particles levitating above the surface in both 1D and 2D simulations. Levitation is of interest to planetary scientists since it provides a way to quickly redistribute the surface dust particles over a body. However, there is currently no method to predict whether or not a certain initial state will result in levitation. We have developed a method to provide constraints on the initial states that result in levitation as a function of dust particle size and central body gravity. Additionally, our method can be applied to several models of the plasma sheath. Thus, we limit the guesswork involved in determining which initial conditions result in levitation. We provide a more detailed understanding of levitation phenomena couched in terms of the commonly recognized spring-mass system. This method of understanding dust motion removes the dependency on the launching mechanism, which remains fraught with controversy. Once a feasible dust launching mechanism is identified (be it micrometeoroid bombardment or electrostatic lofting), our method will allow the community to quickly ascertain if dust levitation will occur in situ or if it is simply a numerical artifact. In addition to

  8. Thermal effects of impact bombardments on Noachian Mars

    NASA Astrophysics Data System (ADS)

    Abramov, Oleg; Mojzsis, Stephen J.

    2016-05-01

    Noachian (prior to ca. 3700 Ma) terranes are the oldest and most heavily cratered landscapes on Mars, with crater densities comparable to the ancient highlands of the Moon and Mercury. Intense early cratering affected Mars by melting and fracturing its crust, draping large areas in impact ejecta, generating regional-scale hydrothermal systems, and increasing atmospheric pressure (and thereby, temperature) to periodically re-start an otherwise moribund hydrological cycle. Post primary-accretionary bombardment scenarios that shaped early Mars can be imagined in two ways: either as a simple exponential decay with an approximately 100 Myr half-life, or as a "sawtooth" timeline characterized by both faster-than-exponential decay from primary accretion and relatively lower total delivered mass. Indications are that a late bombardment spike was superposed on an otherwise broadly monotonic decline subsequent to primary accretion, of which two types are investigated: a classical "Late Heavy Bombardment" (LHB) peak of impactors centered at ca. 3900 Ma that lasted 100 Myr, and a protracted bombardment typified by a sudden increase in impactor flux at ca. 4100-4200 Ma with a correspondingly longer decay time (≤400 Myr). Numerical models for each of the four bombardment scenarios cited above show that the martian crust mostly escaped exogenic melting from bombardment. We find that depending on the chosen scenario, other physical effects of impacts were more important than melt generation. Model output shows that between 10 and 100% of the Noachian surface was covered by impact craters and blanketed in resultant (hot) ejecta. If early Mars was generally arid and cold, impact-induced heating punctuated this surface state by intermittently destabilizing the near-subsurface cryosphere to generate regional-scale hydrothermal systems. Rather than being deleterious to the proclivity of Noachian Mars to host an emergent biosphere, this intense early impact environment instead

  9. Peculiarities of the Field Electron Emission from Dust Grains

    SciTech Connect

    Richterova, I.; Beranek, M.; Pavlu, J.; Nemecek, Z.; Safrankova, J.

    2008-09-07

    The goal of the paper is investigation of the electron field emission that limits the attainable grain charge and can prevent electrostatic fragmentation of loosely bounded aggregates of dust grains. We have found that the effective work function of the spherical amorphous carbon grains does not depend on the relative beam energy. Preliminary results on an influence of the ion treatment/cleaning using the simultaneous electron and ion bombardments are discussed.

  10. Allergies, asthma, and dust

    MedlinePlus

    Allergic rhinitis - dust ... make allergies or asthma worse are called triggers. Dust is a common trigger. When your asthma or allergies become worse due to dust, you are said to have a dust allergy. ...

  11. 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.

  12. 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.

  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. 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.

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

    NASA Astrophysics Data System (ADS)

    Flaherty, William; Austin, Joanna

    2013-11-01

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

  16. High pressure composite tank behaviour under an hypervelocity impact

    NASA Astrophysics Data System (ADS)

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

    2001-10-01

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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Discrete shear failure planes resulting from oblique hypervelocity impacts

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  4. 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.

  5. Study of hypervelocity projectile impact on thick metal plates

    DOE PAGESBeta

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

    2016-01-01

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

  6. Debris area distribution of spacecraft under hypervelocity impact

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  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. 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.

  9. The effect of simulated hypervelocity space debris on polymers

    SciTech Connect

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

    2004-11-08

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  11. 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.

  12. 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.

  13. The Impact Rate on Solar System Satellites During the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Dones, Henry C. Luke; Levison, H. F.

    2012-10-01

    Nimmo and Korycansky (2012; henceforth NK12) found that if the outer Solar System underwent a Late Heavy Bombardment (LHB) in the Nice model, the mass striking the icy satellites at speeds up to tens of km/s would have vaporized so much ice that moons such as Mimas, Enceladus, and Miranda would have been devolatilized. NK12's possible explanations of this apparent discrepancy with observations include (1) the mass influx was a factor of 10 less than that in the Nice model; (2) the mass distribution of the impactors was top-heavy, so that luck might have saved some of the moons from suffering large, vapor-removing impacts; or (3) the inner moons formed after the LHB. NK12 calculated the mass influx onto the satellites from the lunar impact rate estimated by Gomes et al. (2005) and scaling factors calculated by Zahnle et al. (1998, 2003; also see Barr and Canup 2010). Production of vapor in hypervelocity impacts was calculated from Kraus et al. (2011). We are calculating impact rates onto the giant planets and their moons in the context of the "Nice II" model (Levison et al. 2011). We find that NK12's assumed influx is an overestimate, by an amount we are quantifying. We will discuss implications for the origin of icy satellites. We thank the NASA Lunar Science Institute (http://lunarscience.nasa.gov/) for support. Barr, A.C., Canup, R.M., Nature Geoscience 3, 164-167 (2010). Gomes, R., Levison, H.F., Tsiganis, K., Morbidelli, A., Nature 435, 466-469 (2005). Kraus, R.G., Senft, L.E., Stewart, S.T., Icarus 214, 724-738 (2011). Levison, H.F., Morbidelli, A., Tsiganis, K., Nesvorný, D., Gomes, R., Astron. J. 142, article id. 152 (2011). Nimmo, F., Korycansky, D.G., Icarus 219, 508-510 (2012). Zahnle, K., Dones, L., Levison, H.F., Icarus 136, 202-222 (1998). Zahnle, K., Schenk, P., Levison, H.F., Dones, L., Icarus 163, 263-289 (2003).

  14. Aerogel dust collection for in situ mass spectrometry analysis

    NASA Astrophysics Data System (ADS)

    Jones, S. M.; Anderson, M. S.; Davies, A. G.; Kirby, J. P.; Burchell, M. J.; Cole, M. J.

    2015-02-01

    The current technique for conducting in situ mass spectroscopic analysis of dust around extraterrestrial bodies is to have the dust impact a solid plate and analyze the atoms and molecular fragments resulting from the high speed impact. Due to the fact that the kinetic energy from the impact is converted primarily to thermal energy, much of the organic compounds present in the dust may be significantly altered or destroyed. To avoid this problem, aerogel could be used to capture the dust grains, largely intact, maintaining the integrity of the organic compounds in the interior of the dust grains. To demonstrate that organic molecules, present as minor components of silica particles, would survive hypervelocity capture in aerogel and can then be analyzed with mass spectrometry, several light gas gun impact tests and analyses were conducted. Fine particles containing polycyclic aromatic hydrocarbons (PAHs) were captured in aerogel at 5.5 km s-1. The flow of metastable helium from a Direct Analysis Real Time (DART) source was used to desorb and ionize the organics, which were then analyzed with a mass spectrometer. The PAHs were detected and identified by the DART-MS, demonstrating that this method could be used on future flight instruments.

  15. 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.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  19. 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

  20. Identification of minerals and meteoritic materials via Raman techniques after capture in hypervelocity impacts on aerogel

    SciTech Connect

    Burchell, M J; Mann, J; Creighton, J A; Kearsley, A; Graham, G A; Esposito, A P; Franchi, I A; Westphal, A J; Snead, C

    2004-10-04

    For this study, an extensive suite of mineral particles analogous to components of cosmic dust were tested to determine if their Raman signatures can be recognized after hypervelocity capture in aerogel. The mineral particles were mainly of greater than 20 micrometers in size and were accelerated onto the silica aerogel by light gas gun shots. It was found that all the individual minerals captured in aerogel could be subsequently identified using Raman (or fluorescent) spectra. The beam spot size used for the laser illumination was of the order of 5 micrometers, and in some cases the captured particles were of a similar small size. In some samples fired into aerogel there was observed a shift in the wavenumbers of some of the Raman bands, a result of the trapped particles being at quite high temperatures due to heating by the laser. Temperatures of samples under laser illumination were estimated from the relative intensities of Stokes and anti-Stokes Raman bands, or, in the case of ruby particles, from the wavenumber of fluorescence bands excited by the laser. It was found that the temperature of particles in aerogel varied greatly, dependent upon laser power and the nature of the particle. In the worst case, some particles were shown to have temperatures in the 500-700 C range at a laser power of about 3 mW at the sample. However most of the mineral particles examined at this laser power had temperatures below 200 C. This is sufficiently low a temperature not to damage most materials expected to be found captured in aerogel in space. In addition, selected meteorite samples were examined to obtain Raman signatures of their constituent minerals and were then shot into aerogel. It was possible to find several Raman signatures after capture in aerogel and obtain a Raman map of a whole grain in situ in the aerogel. Finally, a Raman analysis was carried out of a particle captured in aerogel in space and carbonaceous material identified. In general therefore it is

  1. Dating Howardite Melt Clasts: Evidence for an Extended Vestan Bombardment?

    NASA Technical Reports Server (NTRS)

    Cartwright, J. A.; Hodges, K. V.; Wadhwa, M.; Mittlefehldt, D. W.

    2016-01-01

    Howardites are polymict breccias that, together with eucrites and diogenites (HED), likely originate from the vestan surface (regolith/ megaregolith), and display a heterogeneous distribution of eucritic and diogenitic material. Melt clasts are also present alongside other regolithic features within howardites, and are noteworthy for their compositional variability and appearance. Melt clasts formed by impact events provide a snapshot of the timings and conditions of surface gardening and bombardment on the vestan surface. By dating such clasts, we aim to better constrain the timings of impact events on Vesta, and to establish whether the impact flux in the asteroid belt was similar to that on the Moon. As the Moon is used as the basis for characterising impact models of the inner solar system, it is necessary to verify that apparent wide-scale events are seen in other planetary bodies. In particular, the observed clustering of Apollo melt clast ages between 3.8-4.0 Ga has led to two hypotheses: 1) The Moon was subjected to a sudden event - 'Lunar Cataclysm' or period of 'Late Heavy Bombardment' (LHB), 2) The age cluster represents the end of an epoch of declining bombardment or 'Heavy Bombardment. No consensus has emerged regarding one or other hypothesis. We are testing these hypotheses by seeking evidence for such events in materials other than those derived from the Moon.

  2. Fertile transgenic wheat from microprojectile bombardment of scutellar tissue.

    PubMed

    Becker, D; Brettschneider, R; Lörz, H

    1994-02-01

    A reproducible transformation system for hexaploid wheat was developed based on particle bombardment of scutellar tissue of immature embryos. Particle bombardment was carried out using a PDS 1000/He gun. Plant material was bombarded with the plasmid pDB1 containing the beta-glucuronidase gene (uidA) under the control of the actin-1 promoter of rice, and the selectable marker gene bar (phosphinothricin acetyltransferase) under the control of the CaMV 35S promoter. Selection was carried out using the herbicide Basta (Glufosinate-ammonium). From a total number of 1050 bombarded immature embryos, in seven independent transformation experiments, 59 plants could be regenerated. Putative transformants were screened for enzyme activity by the histochemical GUS assay using cut leaf material and by spraying the whole plants with an aqueous solution of the herbicide Basta. Twelve regenerants survived Basta spraying and showed GUS-activity. Southern-blot analysis indicated the presence of introduced foreign genes in the genomic DNA of the transformants and both marker genes were present in all plants analysed. To date, four plants have been grown to maturity and set seed. Histochemically stained pollen grains showed a 1:1 segregation of the uidA gene in all plants tested. A 3:1 segregation of the introduced genes was demonstrated by enzyme activity tests and Southern blot analysis of R1 plants. PMID:8148881

  3. JOVIAN EARLY BOMBARDMENT: PLANETESIMAL EROSION IN THE INNER ASTEROID BELT

    SciTech Connect

    Turrini, D.; Coradini, A.; Magni, G.

    2012-05-01

    The asteroid belt is an open window on the history of the solar system, as it preserves records of both its formation process and its secular evolution. The progenitors of the present-day asteroids formed in the Solar Nebula almost contemporary to the giant planets. The actual process producing the first generation of asteroids is uncertain, strongly depending on the physical characteristics of the Solar Nebula, and the different scenarios produce very diverse initial size-frequency distributions (SFDs). In this work, we investigate the implications of the formation of Jupiter, plausibly the first giant planet to form, on the evolution of the primordial asteroid belt. The formation of Jupiter triggered a short but intense period of primordial bombardment, previously unaccounted for, which caused an early phase of enhanced collisional evolution in the asteroid belt. Our results indicate that this Jovian Early Bombardment caused the erosion or the disruption of bodies smaller than a threshold size, which strongly depends on the SFD of the primordial planetesimals. If the asteroid belt was dominated by planetesimals less than 100 km in diameter, the primordial bombardment would have caused the erosion of bodies smaller than 200 km in diameter. If the asteroid belt was instead dominated by larger planetesimals, the bombardment would have resulted in the destruction of bodies as big as 500 km.

  4. Ripple formation on silicon by medium energy ion bombardment.

    PubMed

    Chini, Tapas Kumar; Datta, Debi Prasad; Bhattacharyya, Satya Ranjan

    2009-06-01

    The formation of a self-organized nanoscale ripple pattern after off-normally incident ion bombardment on the surface of amorphous materials, or on semiconductors like silicon that are easily amorphized by ion bombardment, has attracted much attention in recent years from the point of view of both theory and applications. As the energy of the impinging ions increases from low to medium, i.e. several hundred eV to a few tens of keV, the ratio of amplitude to wavelength of the generated ripple pattern becomes so large that inter-peak shadowing of the incident ion flux takes place. Morphologically, the sinusoidal surface profile starts to become distorted after prolonged ion bombardment under such conditions. Structural and compositional modifications of the ripple morphology generated under shadowing conditions include the formation of a thicker amorphous layer with high incorporation of argon atoms in the form of nanometer sized bubbles around the middle part of the front slope of the ripple facing the ion beam, as compared to the rear slope. The present paper reviews recent developments in the experimental study of morphological, structural and compositional aspects of ripple patterns generated on a silicon surface after medium keV (30-120 keV) argon bombardment mainly at an angle of ion incidence of 60°. PMID:21715743

  5. Advances in fast-atom-bombardment mass spectroscopy

    SciTech Connect

    Hemling, M.E.

    1986-01-01

    A comparison of fast atom bombardment and field desorption mass spectrometry was made to determine relative sensitivity and applicability. A series of glycosphingolipids and a series of protected oligonucleotides of known structure were analyzed to ascertain the potential utility of fast atom bombardment mass spectrometry in the structural elucidation of novel compounds in these classes. Negative ion mass markers were also developed. Fast atom bombardment was found to be one-to-two orders of magnitude more sensitive than field desorption based on the analysis of a limited number of compounds from several classes. Superior sensitivity was not universal and field desorption was clearly better in certain cases. In the negative ion mode in particular, fast atom bombardment was found to be a useful tool for the determination of the primary structure of glycosphingolipids and oligonucleotides. Carbohydrate sequence and branching information, and a fatty acid and lipid base composition were readily obtained from the mass spectra of glycosphingolipids while bidirectional nucleotide sequence, nucleotide base, and protecting group assignments were obtained for oligonucleotides. Based on this knowledge, a tentative structure of a human peripheral nervous system glycosphingolipid implicated in certain cases of disorders such as amyotrophic lateral sclerosis, Lou Gehrig's Disease, was proposed. Suitable negative ion mass markers were found in dispersions of poly(ethylene) and poly(propylene)glycols in a triethylenetetramine matrix, a matrix which also proved useful in the analysis of glycosphingolipids. These polyglycol dispersions provided ions for calibration to 2300 daltons.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1994-03-01

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

  9. 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.

  10. Large Area Lunar Dust Flux Measurement Instrument

    NASA Technical Reports Server (NTRS)

    Corsaro, R.; Giovane, F.; Liou, Jer-Chyi; Burchell, M.; Stansbery, Eugene; Lagakos, N.

    2009-01-01

    The instrument under development is designed to characterize the flux and size distribution of the lunar micrometeoroid and secondary ejecta environment. When deployed on the lunar surface, the data collected will benefit fundamental lunar science as well as enabling more reliable impact risk assessments for human lunar exploration activities. To perform this task, the instrument requirements are demanding. It must have as large a surface area as possible to sample the very sparse population of the larger potentially damage-inducing micrometeorites. It must also have very high sensitivity to enable it to measure the flux of small (<10 micron) micrometeorite and secondary ejecta dust particles. To be delivered to the lunar surface, it must also be very low mass, rugged and stow compactly. The instrument designed to meet these requirements is called FOMIS. It is a large-area thin film under tension (i.e. a drum) with multiple fiber optic displacement (FOD) sensors to monitor displacements of the film. This sensor was chosen since it can measure displacements over a wide dynamic range: 1 cm to sub-Angstrom. A prototype system was successfully demonstrated using the hypervelocity impact test facility at the University of Kent (Canterbury, UK). Based on these results, the prototype system can detect hypervelocity (approx.5 km/s) impacts by particles as small as 2 microns diameter. Additional tests using slow speeds find that it can detect secondary ejecta particles (which do not penetrate the film) with momentums as small as 15 pico-gram 100m/s, or nominally 5 microns diameter at 100 m/s.

  11. Transient Density Enhancements of the Martian Orbiting Dust Torus

    NASA Astrophysics Data System (ADS)

    Juhasz, A.; Horanyi, M.

    2014-12-01

    The moons Phobos and Deimos have been suggested to be responsible for sustaining a permanently present dust cloud around Mars. The equilibrium size and spatial distribution of this dust torus has been the subject of numerous theoretical studies. However, no observational evidence has been found as of yet. Because of the renewed interest in Phobos and Deimos as potential targets for human precursor mission to Mars, there is a new opportunity for the detection of the putative Martian dust clouds using in situ measurements. Both Phobos and Deimos, as all airless bodies in the solar system, are continually bombarded by interplanetary dust grains, generating secondary ejecta particles. The surface gravity escape of these objects are low, hence most secondary particles escapethem, but remain in orbit about Mars. Subsequent perturbations by solar radiation pressure, electromagnetic forces acting on charged grains, and collisions with the moons or Mars itself limit the lifetime of the produced particles. The size dependent production rates and lifetimes set the most abundant particle size range of 10 - 30 micron in radius. Large, but short-lived, dust density enhancements can be predicted during periods of meteor showers. Also, comet Siding Spring will flyby Mars in October, 2014. Its dust tail can 'sand-blast' both Phobos and Deimos, dramatically increasing their dust production for a few hours. We present the results of our numerical studies on the temporal and spatial evolution of the dust clouds raised during highly enhanced production rates that last only hours-to-days.

  12. The dust environment surrounding the E-ring moons Dione, Helene and Polydeuce

    NASA Astrophysics Data System (ADS)

    Moldenhawer, T.; Hoffmann, H.; Seiß, M.; Sachse, M.; Spahn, F.

    2015-10-01

    Compared to the dust clouds around three of the Galilean satellites of Jupiter, no clear Saturnian pendants have been found yet by the CDA detector aboardthe Cassini spacecraft. However, three dust tori and arcs have been detected along the orbits of Pallene, Methone and Anthe in ISS images [1] and the Pallene dust torus was confirmed by in situ CDA measurements [4]. These observations have sparked interest whether the small co-orbital companions to E-ring moons like Dione or Thetys are efficient dust sources. We simulate the motion of dust particles, which originate from hypervelocity impacts of micrometeoroids onto Dione, Helene and Polydeuce [2]. Gravity, Lorentz force, solar radiation pressure and plasma drag are considered for the dynamic evolution of small dust particles. Assuming a steady state distribution, we scale the phase space data with dust production rates based on recent IDP measurements at Saturn [3]. We will present dust particle number densities along the orbits of Dione, Helene and Polydeuce and we will make predictions for the Cassini flybys of Helene and Polydeuce, which take place in the summer and fall this year.

  13. 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.

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

    SciTech Connect

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

    2010-02-01

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

  15. 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.

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

    SciTech Connect

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

    1995-02-01

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

  17. Prototype detector development for measurement of high altitude Martian dust using a future orbiter platform

    NASA Astrophysics Data System (ADS)

    Pabari, Jayesh; Patel, Darshil; Chokhawala, Vimmi; Bogavelly, Anvesh

    2016-07-01

    Dust devils mostly occur during the mid of Southern hemisphere summer on Mars and play a key role in the background dust opacity. Due to continuous bombardment of micrometeorites, secondary ejecta come out from the Moons of the Mars and can easily escape. This phenomenon can contribute dust around the Moons and therefore, also around the Mars. Similar to the Moons of the Earth, the surfaces of the Martian Moons get charged and cause the dust levitation to occur, adding to the possible dust source. Also, interplanetary dust particles may be able to reach the Mars and contribute further. It is hypothesized that the high altitude Martian dust could be in the form of a ring or tori around the Mars. However, no such rings have been detected to the present day. Typically, width and height of the dust torus is ~5 Mars radii wide (~16950 km) in both the planes as reported in the literature. Recently, very high altitude dust at about 1000 km has been found by MAVEN mission and it is expected that the dust may be concentrated at about 150 to 500 km. However, a langmuir probe cannot explain the source of such dust particles. It is a puzzling question to the space scientist how dust has reached to such high altitudes. A dedicated dust instrument on future Mars orbiter may be helpful to address such issues. To study origin, abundance, distribution and seasonal variation of Martian dust, a Mars Orbit Dust Experiment (MODEX) is proposed. In order to measure the Martian dust from a future orbiter, design of a prototype of an impact ionization dust detector has been initiated at PRL. This paper presents developmental aspects of the prototype dust detector and initial results. The further work is underway.

  18. Capture of high-speed interstellar dust analogues in Stardust flight spare aerogel

    NASA Astrophysics Data System (ADS)

    Hillier, J. K.; Postberg, F.; Armes, S.; Bugiel, S.; Butterworth, A.; Dupin, D.; Fielding, L. A.; Fujii, S.; Gainsforth, Z.; Grün, E.; Li, Y. W.; Srama, R.; Sterken, V.; Stodolna, J.; Trieloff, M.; Westphal, A.

    2012-09-01

    We present the results of laboratory calibration campaigns designed to determine the effects of particle density and composition on the dimensions of tracks created by hypervelocity dust grains impacting Stardust flight spare aerogel collectors. Tracks created by dust grains from minerals (olivine, orthopyroxene) and latex (poly-[bis(4-vinylthiophenyl)sulfide]) with conductive coatings (platinum or polypyrrole) have been examined and track diameter correlated with impact velocity and particle material. The analogue tracks and terminal particles are compared with the currently identified Stardust ISPE candidates, indicating that only one particle was captured at the expected speed for an interstellar dust particle of the expected size, with the other particles captured at significantly lower speeds.

  19. Hyper-velocity impact test and simulation of a double-wall shield concept for the Wide Field Monitor aboard LOFT

    NASA Astrophysics Data System (ADS)

    Perinati, E.; Rott, M.; Santangelo, A.; Suchy, S.; Tenzer, C.; Del Monte, E.; den Herder, J.-W.; Diebold, S.; Feroci, M.; Rachevski, A.; Vacchi, A.; Zampa, G.; Zampa, N.

    2014-07-01

    The space mission LOFT (Large Observatory For X-ray Timing) was selected in 2011 by ESA as one of the candidates for the M3 launch opportunity. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM), based on Silicon Drift Detectors (SDDs). In orbit, they would be exposed to hyper-velocity impacts by environmental dust particles, which might alter the surface properties of the SDDs. In order to assess the risk posed by these events, we performed simulations in ESABASE2 and laboratory tests. Tests on SDD prototypes aimed at verifying to what extent the structural damages produced by impacts affect the SDD functionality have been performed at the Van de Graaff dust accelerator at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. For the WFM, where we expect a rate of risky impacts notably higher than for the LAD, we designed, simulated and successfully tested at the plasma accelerator at the Technical University in Munich (TUM) a double-wall shielding configuration based on thin foils of Kapton and Polypropylene. In this paper we summarize all the assessment, focussing on the experimental test campaign at TUM.

  20. 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.

  1. 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.

  2. Two stages of dust delivery from satellites to planetary rings

    NASA Astrophysics Data System (ADS)

    Dikarev, Valeri V.; Krivov, Alexander V.; Grün, Eberhard

    2006-08-01

    Faint rings of micrometre-sized dust particles embrace many planets in the Solar system. As a rule, they are replenished by ejecta from embedded atmosphereless moons. On a number of occasions, the ejecta are generated by hypervelocity meteoroid impacts into the moons. Small ejecta fragments are then swiftly shifted into rings by an array of non-gravitational forces, e.g. radiation pressure or plasma drag. A significant fraction of ejecta mass, however, is contained in relatively big, multi-micrometre fragments which are subject to gravity only. Having escaped from the satellite, they stay close to its orbit and form a belt around planet. This belt is itself a source of ring dust through collisional disruption of its particles. Here the contributions of belts to the respective rings are estimated for selected satellites of Jupiter and Saturn. The belts under review could supply substantially more dust to rings than the direct ejecta from satellites and should be taken into account when estimating ring dust budgets. The belts are very difficult to observe, however, and some of them remain a theoretical proposition. We find an appealing evidence for the belts due to Amalthea and Thebe around Jupiter, and for the belt due to Enceladus around Saturn.

  3. 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.

  4. Initial thin film penetration studies at the Colorado Center for Lunar Dust and Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Shu, A. J.; Collette, A.; Drake, K. J.; Gruen, E.; Horanyi, M.; Kempf, S.; Munsat, T.; Northway, P.; Robertson, S. H.; Srama, R.; Sternovsky, Z.; Thomas, E.; Colorado CenterLunar Dust; Atmospheric Studies

    2011-12-01

    Initial studies of damage caused by hypervelocity impacts of various micrometeorite materials into a range of targets are being performed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS). Cratering studies are initially focused on polyvinylidene fluoride (PVDF) films in order to characterize the crater dependencies on impactor mass, size, and speed, and to better understand its capabilities as a dust detector. Additional cratering studies include optical glass, and geological samples as targets. These studies will lead to a better understanding of damage to spacecraft windows and instruments, and space weathering on airless bodies. In parallel, penetration studies will be conducted to determine how hole sizes in thin film materials depend on the properties of the film and the projectile. These thin film penetration studies will be critical to the design of dust detectors similar to that used on NASA's Stardust and New Horizons spacecraft, and in the design of solar sails. Thin film detectors can also be used to characterize beam profiles of laboratory dust accelerators. These studies are being performed at the 3MV hypervelocity dust accelerator at CCLDAS. The facility can accelerate dust particles up to 10's of km/s with user control over the velocity and mass ranges of particles reaching the target chamber. Complementary studies will be conducted at the Johnson Space Center Light Gas Gun using the same target and particle properties. These parallel studies will allow us to cover an extended range of acceleration parameters as well as better understand the similarities and differences between electrostatic accelerators and light gas guns.

  5. Valence-band states of ion-bombarded polystyrene

    SciTech Connect

    Terrasi, A. ); Foti, G. ); Hwu, Y. ); Margaritondo, G. )

    1991-08-01

    Ion-bombarded polystyrene with a 0.5-keV Ar{sup +} beam has been investigated by means of photoelectron spectroscopy performed with synchrotron radiation. After a dose of 10{sup 15} ions/cm{sup 2} the evolution of the valence band of the bombarded sample towards an amorphous carbonlike configuration is reported. From the analysis of valence-band spectra we estimated the out-diffusion of hydrogen and showed that its electronic states remain well identified and stable until the hydrogen presence is about 35% with respect to the pristine sample. Finally, comparison with mass spectroscopy measurements on deuterated polystyrene has been performed to determine hydrogen evolution during the ion irradiation.

  6. O+ bombardment of an O and O2 Thermosphere

    NASA Astrophysics Data System (ADS)

    McKeown, M.; Johnson, R. E.

    2000-10-01

    Ejection of atoms and molecules from the atmosphere of Mars is caused by energetic O+ pickup-ion bombardment [Luhmann et al, 1992; Jakosky et al.,1994], a process referred to as atmospheric sputtering. This process also occurs on other bodies which have molecules at the exobase such as Europa and Titan. Using a Monte Carlo procedure we calculate the rate of ejection of particles from a model thermosphere composed of O and O2 which is bombarded by energetic O+. To allow for dissociation of O2, collisions between high energy O atoms and O2 molecules are treated using classical molecular dynamics with semi-empirical interaction potentials. O + O collisions are treated with the magic formula method of Zeigler et al.,1985. The effect of molecular binding on the atmospheric sputtering yield is examined.

  7. Thermo-mechanical design aspects of mercury bombardment ion thrusters.

    NASA Technical Reports Server (NTRS)

    Schnelker, D. E.; Kami, S.

    1972-01-01

    The mechanical design criteria are presented as background considerations for solving problems associated with the thermomechanical design of mercury ion bombardment thrusters. Various analytical procedures are used to aid in the development of thruster subassemblies and components in the fields of heat transfer, vibration, and stress analysis. Examples of these techniques which provide computer solutions to predict and control stress levels encountered during launch and operation of thruster systems are discussed. Computer models of specific examples are presented.

  8. Low energy electron bombardment induced surface contamination of Ru mirrors

    NASA Astrophysics Data System (ADS)

    Al-Ajlony, A.; Kanjilal, A.; Catalfano, M.; Harilal, S. S.; Hassanein, A.; Rice, B.

    2012-03-01

    The impact of secondary electrons induced contamination of the Ru surface was investigated. Mirror-like Ru sample was bombarded with low energy (100 eV) electrons and the change in surface chemistry was investigated using X-ray photoelectron spectroscopy (XPS).Along with XPS studies the corresponding effect on in-situ EUV reflectivity was examined by exposing the Ru surface to photons at a wavelength of 13.5 nm in an ultrahigh vacuum chamber. Detailed XPS analyses showed a sudden increase in carbon concentrations on the Ru surface in the first 60 min, followed by a slow but linear growth in carbon concentration. In parallel, a noticeable decrease in water content was observed during the time of electrons irradiation along with slight oxidation of pure Ru surface. All chemical changes were discussed in terms of the electrons bombardment mediated dissociation of water and hydrocarbon molecules. A time dependent EUV reflectivity measurements show insignificant change in reflectivity up to 510 min of electrons bombardment. The impact of water molecules on the Ru surface and the accumulation of carbon through dissociation of residual hydrocarbons is discussed in details.

  9. Transformation of Dendrobium orchid using particle bombardment of protocorms.

    PubMed

    Kuehnle, A R; Sugii, N

    1992-08-01

    Transformed dendrobium orchids (Dendrobium x Jaquelyn Thomas hybrids) were recovered from protocorms bombarded by particles coated with the plasmid pGA482GG/cpPRV4, which contains the plant expressible Nos-NPT II and papaya ringspot virus (PRV) coat protein (CP) genes. Approximately 280 protocorms from four crosses were bombarded and potentially transformed tissues were identified by growth and green color on half-strength Murashige and Skoog medium supplemented with 2% sucrose and 50-100 mg 1(-1) kanamycin sulfate. Kanamycin concentrations that prevented growth of nontransformed tissues could not be used for long-term selection because such levels suppressed the regeneration of potentially transformed tissues. PCR and restriction analysis 21 months after treatment found 13 of 13 plants from two crosses, which appeared kanamycin-tolerant, to contain the Nos-NPT II gene, while only one of these plants carried the vector-linked PRV CP-gene. These results support use of particle bombardment for transformation of this important ornamental monocot. PMID:24201595

  10. Metal ion bombardment of onion skin cell wall

    SciTech Connect

    Sangyuenyongpipat, S.; Vilaithong, T.; Yu, L.D.; Verdaguer, A.; Ratera, I.; Ogletree, D.F.; Monteiro, O.R.; Brown, I.G.

    2004-05-10

    Ion bombardment of living cellular material is a novel subfield of ion beam surface modification that is receiving growing attention from the ion beam and biological communities. Although it has been demonstrated that the technique is sound, in that an adequate fraction of the living cells can survive both the vacuum environment and energetic ion bombardment, there remains much uncertainty about the process details. Here we report on our observations of onion skin cells that were subjected to ion implantation, and propose some possible physical models that tend to support the experimental results. The ion beams used were metallic (Mg, Ti, Fe, Ni, Cu), mean ion energy was typically 30keV, and the implantation fluence was in the range 1014 1016 ions/cm2. The cells were viewed using Atomic Force Microscopy, revealing the formation of microcrater-like structures due to ion bombardment. The implantation depth profile was measured with Rutherford backscattering spectrometry and compared to the results of the TRIM, T-DYN and PROFILE computer codes.

  11. Defect formation in graphene during low-energy ion bombardment

    NASA Astrophysics Data System (ADS)

    Ahlberg, P.; Johansson, F. O. L.; Zhang, Z.-B.; Jansson, U.; Zhang, S.-L.; Lindblad, A.; Nyberg, T.

    2016-04-01

    This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV's up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

  12. A hypervelocity debris simulating technique with laser driven flyer

    NASA Astrophysics Data System (ADS)

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

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

  13. Physics of Interplanetary Dust Collection with Aerogel

    NASA Technical Reports Server (NTRS)

    Anderson, William W.

    1998-01-01

    This report presents the results of research undertaken to study various problems associated with hypervelocity capture of dust particles in aerogel. The primary topics investigated were the properties of shocked aerogel and the requirements for reliable capture of particles on the STARDUST mission. In particular, the viscosity of shocked aerogel has been an open question. The results presented here suggest that the viscosity of aerogel at high impact velocities is negligible, although there remains some uncertainty about lower velocities. The model adopted for viscosity treats the mixture of polymeric silica and decomposition products and finds that, for particle velocities of 6-7 km/s, the viscosity is similar to that typical of light gasses at STP. Expressions for the Hugoniot of aerogel as a function of density were also obtained from the available data. All aerogels of interest for cosmic dust collectors have very similar shock velocity-particle velocity Hugoniot curves. The strength behavior of aerogel for low-speed penetration was measured, but further work is needed to study the proper way to apply this to the issue of terminal deceleration of a dust particle. Preliminary calculations designed to maximize the penetration depths were performed to determine the required density of aerogel to reliably stop a particle in a 3 cm thickness of aerogel (the path length expected for a normal impact into the STARDUST collector). In order to stop a particle of density rho(sub p) and diameter d(sub p), the mean density of the aerogel collector should be no less than that given by the expression bar rho(sub 0) = 1.085 X 10(exp -4 )rho(sub p)d(sub p), for densities measured in g/ cu cm and the particle diameter measured in micrometers.

  14. Dust agglomeration

    NASA Technical Reports Server (NTRS)

    2000-01-01

    John Marshall, an investigator at Ames Research Center and a principal investigator in the microgravity fluid physics program, is studying the adhesion and cohesion of particles in order to shed light on how granular systems behave. These systems include everything from giant dust clouds that form planets to tiny compressed pellets, such as the ones you swallow as tablets. This knowledge should help us control the grains, dust, and powders that we encounter or use on a daily basis. Marshall investigated electrostatic charge in microgravity on the first and second U.S. Microgravity Laboratory shuttle missions to see how grains aggregate, or stick together. With gravity's effects eliminated on orbit, Marshall found that the grains of sand that behaved ever so freely on Earth now behaved like flour. They would just glom together in clumps and were quite difficult to disperse. That led to an understanding of the prevalence of the electrostatic forces. The granules wanted to aggregate as little chains, like little hairs, and stack end to end. Some of the chains had 20 or 30 grains. This phenomenon indicated that another force, what Marshall believes to be an electrostatic dipole, was at work.(The diagram on the right emphasizes the aggregating particles in the photo on the left, taken during the USML-2 mission in 1995.)

  15. Canyon Dust

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03682 Canyon Dust

    These dust slides are located on the wall of Thithonium Chasma.

    Image information: VIS instrument. Latitude -4.1N, Longitude 275.7E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  16. Dust Slides

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03677 Linear Clouds

    Dust slides are common in the dust covered region called Lycus Sulci. A large fracture is also visible in this image.

    Image information: VIS instrument. Latitude 28.1N, Longitude 226.3E. 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  17. Dust collector

    SciTech Connect

    Nelson, R.T.

    1986-10-21

    This patent describes a dust collector comprising: (a) a housing having inlet means for receiving air to be cleaned; (b) a plurality of filter units within the housing; (c) a first centrifugal fan arranged for drawing air through the units for removing dust from the air; (d) a plurality of ducts each connected to a corresponding one of the units at one end and to the first fan at the other end to provide passages for air from the units to the first fan, the ducts through a portion of their length being arranged in side-by-side relationship; (e) a second centrifugal fan for providing reverse flow of air through the ducts to the units, the second fan providing a high volume of air at low pressure; (f) a transverse duct connected to the second fan and extending transversely of the portion of the plurality of ducts and adjacent thereto: (g) a plurality of openings providing communication between the transverse duct and each of the plurality of ducts; (i) rotatable means engaging the vanes for sequentially moving the vanes between the first and second positions.

  18. Microanalysis of Hypervelocity Impact Residues of Possible Interstellar Origin

    NASA Technical Reports Server (NTRS)

    Stroud, Rhonda M.; Achilles, Cheri; Allen, Carlton; Anasari, Asna; Bajt, Sasa; Bassim, Nabil; Bastien, Ron S.; Bechtel, H. A.; Borg, Janet; Brenker, Frank E.; Bridges, John; Brownlee, Donald E.; Burchell, Mark; Burghammer, Manfred; Butterworth, Anna L.; Changela, Hitesh; Cloetens, Peter; Davis, Andrew M.; Doll, Ryan; Floss, Christine; Flynn, George; Fougeray, Patrick; Frank, David; Sandford, Scott A.; Zolensky, Michael E.

    2012-01-01

    The NASA Stardust spacecraft deployed two collector trays, one dedicated to the collection of dust from Comet Wild 2, and the other for the capture of interstellar dust (ISD). The samples were returned successfully to Earth in 2006, and now provide an unprecedented opportunity for laboratory-based microanalysis of materials from the outer solar system and beyond. Results from the cometary sample studies have demonstrated that Wild 2 contains much more refractory condensate material and much less pristine extra-solar material than expected, which further indicates that there was significant transport of inner solar system materials to the Kuiper Belt in the early solar system [1]. The analysis of the interstellar samples is still in the preliminary examination (PE) phase, due to the level of difficulty in the definitive identification of the ISD features, the overall low abundance, and its irreplaceable nature, which necessitates minimally invasive measurements [2]. We present here coordinated microanalysis of the impact features on the Al foils, which have led to the identification of four impacts that are possibly attributable to interstellar dust. Results from the study of four ISD candidates captured in aerogel are presented elsewhere [2].

  19. Interstellar Dust: Contributed Papers

    NASA Technical Reports Server (NTRS)

    Tielens, Alexander G. G. M. (Editor); Allamandola, Louis J. (Editor)

    1989-01-01

    A coherent picture of the dust composition and its physical characteristics in the various phases of the interstellar medium was the central theme. Topics addressed included: dust in diffuse interstellar medium; overidentified infrared emission features; dust in dense clouds; dust in galaxies; optical properties of dust grains; interstellar dust models; interstellar dust and the solar system; dust formation and destruction; UV, visible, and IR observations of interstellar extinction; and quantum-statistical calculations of IR emission from highly vibrationally excited polycyclic aromatic hydrocarbon (PAH) molecules.

  20. Nanoscale surface structuring during ion bombardment of elemental semiconductors

    NASA Astrophysics Data System (ADS)

    Anzenberg, Eitan

    2013-01-01

    Nano-patterning of surfaces with uniform ion bombardment yields a rich phase-space of topographic patterns. Particle irradiation can cause surface ultra-smoothing or self-organized nanoscale pattern formation in surface topography. Topographic pattern formation has previously been attributed to the effects of the removal of target atoms by sputter erosion. In this thesis, the surface morphology evolution of Si(100) and Ge(100) during low energy ion bombardment of Ar+ and Kr+ ions, respectively, is studied. Our facilities for studies of surface processes at the National Synchrotron Light Source (NSLS) allow in-situ characterization of surface morphology evolution during ion bombardment using grazing incidence small angle x-ray scattering (GISAXS). This technique is used to measure in reciprocal space the kinetics of formation or decay of correlated nanostructures on the surface, effectively measuring the height-height correlations. A linear model is used to characterize the early time kinetic behavior during ion bombardment as a function of ion beam incidence angle. The curvature coefficients predicted by the widely used erosive model of Bradley and Harper are quantitatively negligible and of the wrong sign when compared to the observed effect in both Si and Ge. A mass-redistribution model explains the observed ultra-smoothing at low angles, exhibits an instability at higher angles, and predicts the observed 45° critical angle separating these two regimes in Si. The Ge surface evolution during Kr+ irradiation is qualitatively similar to that observed for Ar+ irradiation of Si at the same ion energy. However, the critical angle for Ge cannot be quantitatively reproduced by the simple mass redistribution model. Crater function theory, as developed by Norris et al., incorporates both mass redistributive and erosive effects, and predicts constraining relationships between curvature coefficients. These constraints are compared to experimental data of both Si and Ge

  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. The Lunar Environment: Determining the Health Effects of Exposure to Moon Dusts

    NASA Technical Reports Server (NTRS)

    Khan-Mayberry, Noreen

    2007-01-01

    The Earth s moon presents a hostile environment in which to live and work. There is no atmosphere to protect its surface from the ravages of solar wind and micrometeorite impacts. As a result, the moon s surface is covered with a thin layer of fine, charged, reactive dust capable of entering habitats and vehicle compartments, where it can result in crewmember health problems. During the Apollo missions, lunar dusts were introduced into the crew vehicle, resulting in direct exposure and occasional reports of respiratory, dermal and ocular irritation. In order to study the toxicological effects of lunar dust, NASA formed the Lunar Airborne Dust Toxicity Advisory Group (LADTAG). This interdisciplinary group is comprised of leading experts in space toxicology, lunar geology, space medicine and biomedical research. LADTAG has demonstrated that lunar soil contains several types of reactive dusts, including an extremely fine respirable component. These dusts have highly reactive surfaces in the lunar environment; the grains contain surface coatings which are generated by vapor phases formed by hypervelocity impact of micrometeorites. This unique class of dusts has surface properties that are unlike any Earth based analog. These distinctive properties are why lunar dusts are of great toxicological interest. Understanding how these reactive components behave "biochemically" in a moisture-rich pulmonary environment will aid in determining how toxic these particles are to humans. The data obtained from toxicological examination of lunar dusts will determine the human risk criteria for lunar dust exposure and produce a lunar health standard. LADTAG s analysis of lunar dusts and lunar dust simulants will include detailed lunar particle characterizations, determining the properties of particle activation, reactivation of lunar dust, the process of dust passivation and discerning the pathology of lunar dust exposure via inhalation, intratracheal instillation, cell culture

  3. Dust Measurements in Tokamaks

    SciTech Connect

    Rudakov, D; Yu, J; Boedo, J; Hollmann, E; Krasheninnikov, S; Moyer, R; Muller, S; Yu, A; Rosenberg, M; Smirnov, R; West, W; Boivin, R; Bray, B; Brooks, N; Hyatt, A; Wong, C; Fenstermacher, M; Groth, M; Lasnier, C; McLean, A; Stangeby, P; Ratynskaia, S; Roquemore, A; Skinner, C; Solomon, W M

    2008-04-23

    Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering resolves size of particles between 0.16-1.6 {micro}m in diameter; the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast-framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in 2D with a single camera or 3D using multiple cameras, but determination of particle size is problematic. In order to calibrate diagnostics and benchmark dust dynamics modeling, pre-characterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase of carbon atomic, C2 dimer, and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.

  4. Dust feed mechanism

    DOEpatents

    Milliman, Edward M.

    1984-01-01

    The invention is a dust feed device for delivery of a uniform supply of dust for long periods of time to an aerosolizing means for production of a dust suspension. The device utilizes at least two tandem containers having spiral brushes within the containers which transport the dust from a supply to the aerosolizer means.

  5. Detecting meteoroid streams with an in-situ dust detector above an airless body

    NASA Astrophysics Data System (ADS)

    Szalay, Jamey R.; Horányi, Mihály

    2016-09-01

    The Lunar Dust Experiment (LDEX), aboard NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) successfully mapped the dust density distribution over the lunar surface up to an altitude of ∼ 250 km. LDEX detected dust grains launched off the surface in ejecta plumes generated by impacts of cometary and asteroidal micrometeoroids striking the Moon. While on average LDEX detected particles at a rate of 1 min-1 , periodically it measured bursts of particles at a rate exceeding the average value by up to two orders of magnitude. The timing and location of the most intense period of bursts is used here to independently determine the radiant for the Geminids meteoroid stream. The method is proposed to be of general interest to characterize meteoroid streams bombarding any of the airless bodies in the solar system using in-situ dust detectors.

  6. Electric Dust Devils and Dust Storms

    NASA Astrophysics Data System (ADS)

    Renno, N. O.; Yana, C.

    2004-12-01

    Electrical fields measurements in terrestrial dust devils show that they maintain tremendous charge separation and that their electric fields exceeds the breakdown potential (~10 kV/m) of the Martian atmosphere (Farrell et al., 2002, 2003; Krauss et al., 2002; Renno et al., 2004). Typical Martian dust devils are be up to 100 times larger and much stronger than the small terrestrial analogues. Martian dust devils have higher dust content and may produce even stronger electrical fields. Indeed, the dust devils observed in the Pathfinder images have about 700 times the dust content of the local background atmosphere (Metzger et al., 1999). Thus, strong charge separations and electric-field breakdown are likely to occur on Martian dust devils and dust storms. Our theory (Renno et al., 2004) and laboratory experiments in a Mars chamber shows that collisions between sand and dust particles produce non-thermal microwave radiation. The non-thermal microwave emission allows not only the indirect detection of electric activity but also the determination of the physical properties of Martian sand and dust by remote sensing. Besides being geologically important, electrically charged Martian dust devils and dust storms are potential hazards to Landers and will be dangerous to future astronauts exploring its surface. Indeed, the design of adequate mechanical and electrical systems for these Landers cannot progress effectively without a better understanding of Martian dust devils and dust storms. Moreover, ancillary phenomena associated with electrically charged vortices can ionize atmospheric gases and might have important implications for atmosphere chemistry and even habitability.

  7. Single impact crater functions for ion bombardment of silicon

    SciTech Connect

    Kalyanasundaram, N.; Ghazisaeidi, M.; Freund, J. B.; Johnson, H. T.

    2008-03-31

    The average effect of a single 500 eV incident argon ion on a silicon surface is studied using molecular dynamics simulations. More than 10{sup 3} ion impacts at random surface points are averaged for each of seven incidence angles, from 0 deg. to 28 deg. off normal, to determine a local surface height change function, or a crater function. The crater shapes are mostly determined by mass rearrangement; sputtering has a relatively small effect. Analytical fitting functions are provided for several cases, and may serve as input into kinetic Monte Carlo calculations or stability analyses for surfaces subjected to ion bombardment.

  8. Analysis of glycolipids by fast atom bombardment mass spectrometry.

    PubMed

    Bosch, M P; Parra, J L; Manresa, M A; Ventura, F; Rivera, J

    1989-12-01

    The positive and negative ion fast atom bombardment (FAB) mass spectra of four glycolipids obtained from microbial cultures are reported. The spectra of the glycolipids in the positive ion mode are characterized by abundant [M + Na]+, [M + Na + matrix]+ and [M + 2Na - H]+ species. In negative FAB conditions the molecules yield [M - H]-. Our understanding of the FAB behaviour of glycolipids in both positive and negative modes has been considerably aided in the structure elucidation, without any derivatization or degradation reaction of the compounds studied. The technique allows unambiguous molecular weight determination of low-microgram amounts of these glycolipids purified from biological sources and provides useful fragmentation information. PMID:2611417

  9. Electron-bombarded CCD detectors for ultraviolet atmospheric remote sensing

    NASA Technical Reports Server (NTRS)

    Carruthers, G. R.; Opal, C. B.

    1983-01-01

    Electronic image sensors based on charge coupled devices operated in electron-bombarded mode, yielding real-time, remote-readout, photon-limited UV imaging capability are being developed. The sensors also incorporate fast-focal-ratio Schmidt optics and opaque photocathodes, giving nearly the ultimate possible diffuse-source sensitivity. They can be used for direct imagery of atmospheric emission phenomena, and for imaging spectrography with moderate spatial and spectral resolution. The current state of instrument development, laboratory results, planned future developments and proposed applications of the sensors in space flight instrumentation is described.

  10. Exploring the Early Bombardment of the Inner Solar System

    NASA Astrophysics Data System (ADS)

    Bottke, W.

    2014-04-01

    The early bombardment history of the Inner Solar System is recorded in a number of interesting places (e.g., the surprisingly high abundance of highly siderophile abundances found in the Earth, Moon, and Mars, the observed impact basins found on Mercury, the Moon and Mars, various properties of main belt asteroids and meteorites, etc.). To date, two dominant scenarios have been used to explain these constraints: (i) most impacts came from the tail end of a monotonically-decreasing impactor population created by planet formation processes, and (ii) most impacts were produced by a terminal cataclysm that caused a spike in the impactor flux starting ~4 Gy ago. Interestingly, using numerical studies linked to the available constraints, we find that both scenarios are needed to explain observations. For (i), we will show that leftover planetesimals from the terrestrial planet region were long-lived enough to hit various worlds long after the end of core formation. The record left behind can be used in interesting ways to probe the nature of terrestrial planet formation. For (ii), we will explore new applications of the so-called Nice model, which provides a plausible dynamical mechanism capable of creating a spike of comets/asteroid impactors. Our results suggest that many "late heavy bombardment" impactors came from an unexpected source, and that they possibly continued to hit Earth, Venus, and Mars well after basin formation terminated on the Moon. Interestingly, the history of the Hadean Earth (ca. 4.0-4.5 billion years ago) may be closely linked to this bombardment. With few known rocks older than ~3.8 Ga, the main constraints from this era come from ancient submillimeter zircon grains. Using our bombardment model, we will argue that the surface of the Hadean Earth was widely reprocessed by impacts through mixing and heating of its uppermost layers. This model not only may explains the Pb-Pb age distribution of ancient zircons but also the absence of most early

  11. Smoothening of internal phase boundaries by ion bombardment

    SciTech Connect

    Petersen, J.; Mayr, S.G.

    2005-08-01

    The impact of heavy-ion irradiation on the morphology of bilayers, which are composed of two immiscible metals, is investigated with the help of experiments and molecular-dynamics computer simulations. Using the model system Ag/Ni, our main focus lies on the interface roughness of the Ag/Ni phase boundary and its evolution in the course of ion bombardment. The mechanism which underlies these structural changes is identified as radiation-induced viscous flow--in combination with thermodynamic driving forces due to interface stress.

  12. Enhanced resistance of single-layer graphene to ion bombardment

    SciTech Connect

    Lopez, J. J.; Greer, F.; Greer, J. R.

    2010-05-15

    We report that single-layer graphene on a SiO{sub 2}/Si substrate withstands ion bombardment up to {approx}7 times longer than expected when exposed to focused Ga{sup +} ion beam. The exposure is performed in a dual beam scanning electron microscope/focused ion beam system at 30 kV accelerating voltage and 41 pA current. Ga{sup +} ion flux is determined by sputtering a known volume of hydrogenated amorphous carbon film deposited via plasma-enhanced chemical vapor deposition.

  13. Insulating behavior of magnetic spots in proton-bombarded graphite

    NASA Astrophysics Data System (ADS)

    Schindler, K.; García, N.; Esquinazi, P.; Ohldag, H.

    2008-07-01

    Kelvin probe force microscopy measurements on micrometer small magnetic spots produced by proton bombardment on bulk graphite reveal a charge transfer from the center of the spot to an external ring with potential variation on the order of 50 mV. The total charge in the spot is neutral. The results can be well understood in terms of practically unscreened potentials, an insulating property, although the nonbombarded, surrounding graphite region exhibits good conductance. Scanning transmission x-ray microscopy measurements on magnetic spots prepared on graphitic films reveal similar charge distribution. The insulating behavior is fundamental to understand the magnetism in graphite.

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

    DOE PAGESBeta

    Crawford, David A.

    2015-05-19

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

  15. 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.

  16. 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.

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

    SciTech Connect

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

    2005-02-01

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

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

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

  1. 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.

  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. Relevance of convective turbulent dust emission (CTDE) in the Earth system

    NASA Astrophysics Data System (ADS)

    Klose, Martina; Shao, Yaping; Butler, Harry; Leys, John

    2015-04-01

    Convective turbulence generates localized and intermittent surface shear stress and can effectively entrain dust into the atmosphere. This mechanism is referred to as "Convective Turbulent Dust Emission" (CTDE) and is considered as the most important form of direct aerodynamic dust entrainment. CTDE occurs predominantly at weak mean wind conditions, when the buoyancy production of atmospheric turbulence is most pronounced. CTDE is a stochastic process and does not need to involve the saltation of sand-sized grains. An improved parameterization for CTDE is presented, which represents both aerodynamic lifting and inter-particle cohesive forces as probability distributions. The dust emission scheme therefore accounts for the stochastic nature of CTDE. The scheme was evaluated against field data recorded in the Horqin Sandy Land area in China and during the Japan-Australia Dust Experiment (JADE) in Australia. Coupled to the regional model WRF/Chem, the calibrated dust emission scheme was used to assess the long-term regional contribution of CTDE to the overall dust budget for Australia. We show that a persistent background dust concentration can be generated by CTDE. The modeled dust concentrations were compared to PM10 measurements monitored by the DustWatch Australia network. An estimate on the relevance of CTDE compared to saltation bombardment at the local and regional scales is given and implications for climate are highlighted.

  4. 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

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  6. 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.

  7. Dust Avalanches

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Crater wall dust avalanches in southern Arabia Terra.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 10.3, Longitude 24.5 East (335.5 West). 19 meter/pixel resolution.

  8. Asymmetries in the dust flux at Mercury

    NASA Astrophysics Data System (ADS)

    Borin, P.; Cremonese, G.; Bruno, M.; Marzari, F.

    2016-01-01

    The planet Mercury has an extended and tenuous exosphere made up of atoms that are ejected from the surface by energetic processes, including hypervelocity micrometeoritic impacts, photon-stimulated desorption by UV radiation, and ion sputtering. Meteoroid impacts of particles smaller than 1 cm, which are important for replenishing the exosphere daily, are not well-studied. We present a systematic investigation of spatial asymmetries in the impactor rate of micrometeoroids over Mercury's surface as a function of planetary true anomaly (TAA). Since the orbit of Mercury is quite eccentric a seasonal variation of the impact rate is to be expected. We find that the source peaks near the planetary equator for most TAA. Contrary to previous assumptions, we find the source to be non-uniform in local time. Only certain regions of Mercury are exposed to dust as a result of the orbital elements of Mercury and of the Main Belt particles (inclination less than 20°). Our results offer important constraints on transport models used for interpreting measurements of this exosphere, but also inform studies of space weathering of Mercury's surface.

  9. Dust particle dynamics in atmospheric dust devils

    NASA Astrophysics Data System (ADS)

    Izvekova, Yulia; Popel, Sergey

    2016-04-01

    Dust particle dynamics is modeled in the Dust Devils (DDs). DD is a strong, well-formed, and relatively long-lived whirlwind, ranging from small (half a meter wide and a few meters tall) to large (more than 100 meters wide and more than 1000 meters tall) in Earth's atmosphere. We develop methods for the description of dust particle charging in DDs, discuss the ionization processes in DDs, and model charged dust particle motion. Our conclusions are consistent with the fact that DD can lift a big amount of dust from the surface of a planet into its atmosphere. On the basis of the model we perform calculations and show that DDs are important mechanism for dust uplift in the atmospheres of Earth and Mars. Influence of DD electric field on dynamics of dust particles is investigated. It is shown that influence of the electric field on dust particles trajectories is significant near the ground. At some altitude (more then a quarter of the height of DD) influence of the electric field on dust particles trajectories is negligible. For the calculation of the dynamics of dust electric field can be approximated by effective dipole located at a half of the height of DD. This work was supported by the Russian Federation Presidential Program for State Support of Young Scientists (project no. MK-6935.2015.2).

  10. Compositional Analysis of Interstellar Dust as seen by the Cassini Cosmic Dust Analyzer III

    NASA Astrophysics Data System (ADS)

    Fiege, K.; Trieloff, M.; Guglielmino, M.; Hillier, J.; Postberg, F.; Srama, R.; Kempf, S.; Blum, J.

    2013-12-01

    The goal of this work is to evaluate constraints on the composition of interstellar dust (ISD) grains, obtained via impact ionization time-of-flight mass spectroscopy with the Cosmic Dust Analyzer (CDA) onboard the Cassini spacecraft at Saturn. 25 ISD candidates have been extracted from the vast Cassini CDA data set, based on the evaluation of their dynamical properties. To derive chemical composition from time-of-flight mass spectra of high energy particle impacts, we calibrated the laboratory unit of the CDA [1], and the high resolution Large Area Mass Analyzer (LAMA) [2] with a specifically manufactured orthopyroxene dust analogue. For particle impact simulations we utilized a 2MV Van de Graaff accelerator at Heidelberg [3]. The dust analogue material was analyzed by geochemical standard techniques (scanning electron microscope - SEM; electron microprobe analysis - EMPA), and ground to sub-micron size and coated with a conductive Pt-layer for the acceleration through an electromagnetic field [4]. We inferred sensitivity coefficients for impact ionization TOF mass spectra, so that mass spectra from the CDA and LAMA could be compared with with typical compositions of terrestrial and cosmochemically relevant silicate minerals, and bulk compositions.The suite of ISD canditates can be divided into a Mg-rich fraction with low Ca-content and a Mg-rich fraction with higher Ca-content. Comparing the ISD candidate compositions to cosmochemically relevant reservoirs, it can be shown that the Mg-dominated ISD candidate data plot close to a solar or cosmic composition (CI), possibly slightly volatile depleted. References:[1]R. Srama, et al., The Cassini Cosmic Dust Analyzer. Space Sci. Rev., 114: 465-518 ( 2004). [2] R. Srama, et al., Laboratory Tests of the Large Area Mass Analyser. Dust in Planetary Systems, 643:209-212 (2007). [3]A. Mocker, et al., A 2mv van de graaff accelerator as a tool for planetary and impact physics research. Rev. Sci. Instr. (2011), [4] J. K

  11. Induction of antioxidant enzyme activity and lipid peroxidation level in ion-beam-bombarded rice seeds

    NASA Astrophysics Data System (ADS)

    Semsang, Nuananong; Yu, LiangDeng

    2013-07-01

    Low-energy ion beam bombardment has been used to mutate a wide variety of plant species. To explore the indirect effects of low-energy ion beam on biological damage due to the free radical production in plant cells, the increase in antioxidant enzyme activities and lipid peroxidation level was investigated in ion-bombarded rice seeds. Local rice seeds were bombarded with nitrogen or argon ion beams at energies of 29-60 keV and ion fluences of 1 × 1016 ions cm-2. The activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST) and lipid peroxidation level were assayed in the germinated rice seeds after ion bombardment. The results showed most of the enzyme activities and lipid peroxidation levels in both the argon and nitrogen bombarded samples were higher than those in the natural control. N-ion bombardment could induce higher levels of antioxidant enzyme activities in the rice samples than the Ar-ion bombardment. Additional effects due to the vacuum condition were found to affect activities of some antioxidant enzymes and lipid peroxidation level. This study demonstrates that ion beam bombardment and vacuum condition could induce the antioxidant enzyme activity and lipid peroxidation level which might be due to free radical production in the bombarded rice seeds.

  12. 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)

  13. 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.

  14. Molecular dynamics simulation of graphene bombardment with Si ion

    NASA Astrophysics Data System (ADS)

    Qin, Xin-Mao; Gao, Ting-Hong; Yan, Wan-Jun; Guo, Xiao-Tian; Xie, Quan

    2014-03-01

    Molecular dynamics simulations with Tersoff-Ziegler-Biersack-Littmark (Tersoff-ZBL) potential and adaptive intermolecular reactive empirical bond order (AIREBO) potential are performed to study the effect of irradiated graphene with silicon ion at several positions and energy levels of 0.1-1000 eV. The simulations reveal four processes: absorption, replacement, transmission and damage. At energies below 110 eV, the dominant process is absorption. For atom in group (a), the process that takes place is replacement, in which the silicon ion removes one carbon atom and occupies the place of the eliminated atom at the incident energy of 72-370 eV. Transmission is present at energies above 100 eV for atom in group (d). Damage is a very important process in current bombardment, and there are four types of defects: single vacancy, replacement-single vacancy, double vacancy and nanopore. The simulations provide a fundamental understanding of the silicon bombardment of graphene, and the parameters required to develop graphene-based devices by controlling defect formation.

  15. Hazards of explosives dusts

    NASA Astrophysics Data System (ADS)

    The Bureau of Mines has investigated the hazards of military explosives dispersed as dust clouds in a 20-L test chamber. For purposes of personnel safety, the spark ignitability of the explosives in the form of unconfined dust layers was also studied. The 20-L data show that most of the explosive dusts were capable of sustaining explosions as dust clouds dispersed in air and some dusts were even capable of sustaining explosions when dispersed in nitrogen. The finest sizes of explosive dusts were less reactive than the larger sizes; this is opposite to the particle size effect observed previously for the pure fuel dusts. The data for the explosive dusts were compared to those for pure fuel dusts.

  16. Ion microprobe elemental analyses of impact features on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, Jerry L.; Wortman, Jim J.; Griffis, Dieter P.

    1992-01-01

    Hypervelocity impact features from very small particles (less than 3 microns in diameter) on several of the electro-active dust sensors used in the Interplanetary Dust Experiment (IDE) were subjected to elemental analysis using an ion microscope. The same analytical techniques were applied to impact and containment features on a set of ultra-pure, highly polished single crystal germanium wafer witness plates that were mounted on tray B12. Very little unambiguously identifiable impactor debris was found in the central craters or shatter zones of small impacts in this crystalline surface. The surface contamination, ubiquitous on the surface of the Long Duration Exposure Facility, has greatly complicated data collection and interpretation from microparticle impacts on all surfaces.

  17. Dust: A major environmental hazard on the earth's moon

    SciTech Connect

    Heiken, G.; Vaniman, D.; Lehnert, B.

    1990-01-01

    On the Earth's Moon, obvious hazards to humans and machines are created by extreme temperature fluctuations, low gravity, and the virtual absence of any atmosphere. The most important other environmental factor is ionizing radiation. Less obvious environmental hazards that must be considered before establishing a manned presence on the lunar surface are the hazards from micrometeoroid bombardment, the nuisance of electro-statically-charged lunar dust, and an alien visual environment without familiar clues. Before man can establish lunar bases and lunar mining operations, and continue the exploration of that planet, we must develop a means of mitigating these hazards. 4 refs.

  18. Dust: A major environmental hazard on the Earth's moon

    NASA Astrophysics Data System (ADS)

    Heiken, Grant; Vaniman, David; Lehnert, Bruce

    On the Earth's Moon, obvious hazards to humans and machines are created by extreme temperature fluctuations, low gravity, and the virtual absence of any atmosphere. The most important other environmental factor is ionizing radiation. Less obvious environmental hazards that must be considered before establishing a manned presence on the lunar surface are the hazards from micrometeoroid bombardment, the nuisance of electro-statically-charged lunar dust, and an alien visual environment without familiar clues. Before man can establish lunar bases and lunar mining operations, and continue the exploration of that planet, we must develop a means of mitigating these hazards.

  19. A New Parameter Regime for Dust in Plasma: the Case of Dense and Supersonic Plasma Flows

    SciTech Connect

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

    2008-09-07

    The co-existence between charged micron-size particulates of matter and plasma electrons and ions can lead to interesting physics phenomena. Some of the most spectacular observations in laboratory low ionized gases include the formation of aligned dust structures, the propagation of dust waves or self-organization leading to dust voids. Here, the dust dynamics is established by the forces of gravity, of electrostatic interaction with electric fields within the plasma, of friction with the neutral gas, and by the Coulomb repulsion between grains. Measurements of dust trajectories have been carried out in situ when the plasma density is about 6-7 orders of magnitude higher than in typical laboratory dusty plasmas, i.e. {approx}10{sup 22} m{sup -3}, and the ion temperature is a few eV. The plasma flows at speeds of the order of 20-60 km/s. Two observed features characterize dust in this new plasma regime: the plasma drag force dominates over all other forces acting on the grains and the microparticles are heated to temperatures sufficiently high, to become self-illuminated. Simultaneous observation at different moments in time of up to a few hundred flying dust grains has been possible due to the timing capabilities of a high-speed camera equipped with a telephoto lens. Dust speed of a few km/s and accelerations of {approx}10{sup 5}-10{sup 6} m/s{sup 2} have been inferred using the time-of-flight technique. Among the applications of hypervelocity dust are local diagnostics performed on hot plasmas, interstellar propulsion or simulation of meteorite impacts.

  20. A New Parameter Regime for Dust in Plasma: the Case of Dense and Supersonic Plasma Flows

    NASA Astrophysics Data System (ADS)

    Ticoş, Cătălin M.; Wang, Zhehui; Wurden, Glen. A.

    2008-09-01

    The co-existence between charged micron-size particulates of matter and plasma electrons and ions can lead to interesting physics phenomena. Some of the most spectacular observations in laboratory low ionized gases include the formation of aligned dust structures, the propagation of dust waves or self-organization leading to dust voids. Here, the dust dynamics is established by the forces of gravity, of electrostatic interaction with electric fields within the plasma, of friction with the neutral gas, and by the Coulomb repulsion between grains. Measurements of dust trajectories have been carried out in situ when the plasma density is about 6-7 orders of magnitude higher than in typical laboratory dusty plasmas, i.e. ~1022 m-3, and the ion temperature is a few eV. The plasma flows at speeds of the order of 20-60 km/s. Two observed features characterize dust in this new plasma regime: the plasma drag force dominates over all other forces acting on the grains and the microparticles are heated to temperatures sufficiently high, to become self-illuminated. Simultaneous observation at different moments in time of up to a few hundred flying dust grains has been possible due to the timing capabilities of a high-speed camera equipped with a telephoto lens. Dust speed of a few km/s and accelerations of ~105-106 m/s2 have been inferred using the time-of-flight technique. Among the applications of hypervelocity dust are local diagnostics performed on hot plasmas, interstellar propulsion or simulation of meteorite impacts.

  1. Reduction and analysis of data from cosmic dust experiments on Mariner 4, OGO 3, and Lunar Explorer 35

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The analysis of data from the cosmic dust experiment on three NASA missions is discussed. These missions were Mariner IV, OGO III, and Lunar Explorer 35. The analysis effort has included some work in the laboratory of the physics of microparticle hypervelocity impact. This laboratory effort was initially aimed at the calibration and measurements of the different sensors being used in the experiment. The latter effort was conducted in order to better understand the velocity and mass distributions of the picogram sized ejecta particles.

  2. Evidence Supporting an Early as Well as Late Heavy Bombardment on the Moon

    NASA Technical Reports Server (NTRS)

    Frey, Herbert

    2015-01-01

    Evidence supporting an intense early bombardment on the Moon in addition to the traditional Late Heavy Bombardment at approx. 4 BY ago include the distribution of N(50) Crater Retention Ages (CRAs) for candidate basins, a variety of absolute age scenarios for both a "young" and an "old" Nectaris age, and the decreasing contrasts in both topographic relief and Bouguer gravity with increasing CRA.

  3. Charge collection during hypervelocity penetrations of thin foils

    NASA Technical Reports Server (NTRS)

    Peterson, Robert B.

    1994-01-01

    The following represents trajectory sensor development work for the space-station-based Cosmic Dust Collection Facility (CDCF). This facility-class payload was to expose some 7 sq m of NASA-provided general-user instruments in addition to three instruments provided by formally selected principal investigators. The preferred trajectory sensor for this general-user instrument envisioned the detection of impact-triggered plasma for both velocity measurement and location instruments. Space station developments in late 1992/early 1993 lead to cancellation of this potential flight project, for both technical and fiscal reasons. This precipitated termination of all plasma detection work at JSC on behalf of CDCF's general-user instrument. The following comprises three informal reports that summarize the CDCF efforts regarding plasma sensing for trajectory determinations. The reports were initially written for internal CDCF use and were not widely distributed. Because no formal publications are envisioned at present, the three reports are included in full in this document. They not only demonstrate that substantial progress was accomplished in the development of plasma trajectory sensors during 1990-1992, but the results are hopefully of interest and use to others who may continue these developments. The chronological sequence of these three reports is reversed, with the first containing the latest information.

  4. Capture of Hypervelocity Particles with Low-Density Aerogel

    NASA Technical Reports Server (NTRS)

    Hoerz, Friedrich; Cintala, Mark J.; Zolensky, Michael E.; Bernhard, Ronald B.; Haynes, Gerald; See, Thomas H.; Tsou, Peter; Brownlee, Donald E.

    1998-01-01

    Recent impact experiments conducted at Johnson Space Center supported a space-exposed flight instrument called the orbital debris collector (ODC) to see whether SiO2 acrogel performed adequately as a collector to capture cosmic dust particles and/or manmade debris, or whether additional development is needed. The first ODC was flown aboard the Mir for 18 months, while the second will be flown aboard a spacecraft (Stardust, to be launched in 1999) that will encounter the comet Wild 2 and return to Earth. Aerogels are highly porous materials that decelerate high-velocity particles without substantial melting or modifications to the particles' components; in other denser materials, these particles would melt or vaporize upon impact. The experimental data in this report must be considered somewhat qualitative because they are characterized by substantial, if not intolerable, scatter, possibly due to experimental difficulties in duplicating given sets of initial impact conditions. Therefore, this report is a chronological guide of the experimenters' attempts, difficulties, progress, and evaluations for future tests.

  5. Dust Plume off Mauritania

    NASA Technical Reports Server (NTRS)

    2007-01-01

    A thick plume of dust blew off the coast of Mauritania in western Africa on October 2, 2007. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite observed the dust plume as it headed toward the southwest over the Atlantic Ocean. In this image, the dust varies in color from nearly white to medium tan. The dust plume is easier to see over the dark background of the ocean, but the plume stretches across the land surface to the east, as well. The dust plume's structure is clearest along the coastline, where relatively clear air pockets separate distinct puffs of dust. West of that, individual pillows of dust push together to form a more homogeneous plume. Near its southwest tip, the plume takes on yet another shape, with stripes of pale dust fanning out toward the northwest. Occasional tiny white clouds dot the sky overhead, but skies are otherwise clear.

  6. An 8-cm electron bombardment thruster for auxiliary propulsion

    NASA Technical Reports Server (NTRS)

    Hudson, W. R.; Banks, B. A.

    1973-01-01

    Thruster size, beam current level, and specific impulse trade-offs are considered for mercury electron bombardment ion thrusters to be used for north-south station keeping of geosynchronous spacecraft. An 8-cm diameter thruster operating at 2750 seconds specific impulse at thrust levels of 4.4 mN (1 m1b) to 8.9 mN (2 m6b) with a design life of 20,000 hours and 10,000 cycles is being developed. The thruster will have a dished two-grid system capable of thrust vectoring of + or - 10 degrees in two orthogonal directions. A preliminary thruster has been fabricated and tested; thruster performance characteristics have been determined at 4.45, 6.68, and 8.90 millinewtons.

  7. Optical radiation from regions downstream of mercury bombardment thrusters

    NASA Technical Reports Server (NTRS)

    Milder, N. L.; Sovey, J. S.

    1972-01-01

    A 0.5 meter focal length, plane grating monochromator was used to measure the radiance of spectral radiation emanating from regions downstream of a mercury bombardment thruster. The wavelength range investigated was 2800 A. This radiation was due primarily to the radiative decay of excited mercury atoms exhausted from the thruster. Radiance values ranged from 10 to the minus 11th power to 10 to the minus 9th power W/sq cm sr, varying with wavelength. For resonant radiation, the spectral radiance may exceed 10 to the minus 8th power W/sq cm sr. From such radiance measurements, it was concluded that the thruster background radiation should not interfere with the control functions of a star tracker viewing through the thruster exhaust, provided that the tracker is designed to operate with a sufficiently small field of view.

  8. Uses of ion bombardment in thin-film deposition

    SciTech Connect

    Erck, R.A.; Fenske, G.R.; Erdemir, A.

    1990-10-01

    Use of plasma- and ion-beam-modified surfaces and surface coatings in continually expanding in engineering disciplines. The purpose of these modifications and treatments is to impart favorable properties, such as wear resistance and lubricity, to the surfaces, while at the same time retaining the strength or toughness of the bulk materials. Energetic-ion bombardment can be used to modify the structural and chemical properties of surfaces or applied coatings. Ion-implantation has been used for many years, and recently, other surface-modification techniques, among them ion-beam mixing and ion-beam-assisted deposition, have attracted attention because they permit application of highly adherent lubricious and wear-resistant films. In this paper, ion-beam techniques are described from the viewpoint of ion-surface interactions, and some avenues for the engineering of tribological surfaces are presented. 100 refs., 4 figs.

  9. Bombarding Cancer: Biolistic Delivery of therapeutics using Porous Si Carriers

    NASA Astrophysics Data System (ADS)

    Zilony, Neta; Tzur-Balter, Adi; Segal, Ester; Shefi, Orit

    2013-08-01

    A new paradigm for an effective delivery of therapeutics into cancer cells is presented. Degradable porous silicon carriers, which are tailored to carry and release a model anti-cancer drug, are biolistically bombarded into in-vitro cancerous targets. We demonstrate the ability to launch these highly porous microparticles by a pneumatic capillary gene gun, which is conventionally used to deliver cargos by heavy metal carriers. By optimizing the gun parameters e.g., the accelerating gas pressure, we have successfully delivered the porous carriers, to reach deep targets and to cross a skin barrier in a highly spatial resolution. Our study reveals significant cytotoxicity towards the target human breast carcinoma cells following the delivery of drug-loaded carriers, while administrating empty particles results in no effect on cell viability. The unique combination of biolistics with the temporal control of payload release from porous carriers presents a powerful and non-conventional platform for designing new therapeutic strategies.

  10. Sputtering yield of Pu bombarded by fission Fragments from Cf

    SciTech Connect

    Danagoulian, Areg; Klein, Andreas; Mcneil, Wendy V; Yuan, Vincent W

    2008-01-01

    We present results on the yield of sputtering of Pu atoms from a Pu foil, bombarded by fission fragments from a {sup 252}Cf source in transmission geometry. We have found the number of Pu atoms/incoming fission fragments ejected to be 63 {+-} 1. In addition, we show measurements of the sputtering yield as a function of distance from the central axis, which can be understood as an angular distribution of the yield. The results are quite surprising in light of the fact that the Pu foil is several times the thickness of the range of fission fragment particles in Pu. This indicates that models like the binary collision model are not sufficient to explain this behavior.

  11. Plasma properties in electron-bombardment ion thrusters

    NASA Technical Reports Server (NTRS)

    Matossian, J. N.; Beattie, J. R.

    1987-01-01

    The paper describes a technique for computing volume-averaged plasma properties within electron-bombardment ion thrusters, using spatially varying Langmuir-probe measurements. Average values of the electron densities are defined by integrating the spatially varying Maxwellian and primary electron densities over the ionization volume, and then dividing by the volume. Plasma properties obtained in the 30-cm-diameter J-series and ring-cusp thrusters are analyzed by the volume-averaging technique. The superior performance exhibited by the ring-cusp thruster is correlated with a higher average Maxwellian electron temperature. The ring-cusp thruster maintains the same fraction of primary electrons as does the J-series thruster, but at a much lower ion production cost. The volume-averaged predictions for both thrusters are compared with those of a detailed thruster performance model.

  12. ATS-6 - Cesium bombardment engine north-south stationkeeping experiment

    NASA Technical Reports Server (NTRS)

    Worlock, R. M.; James, E. L.; Hunter, R. E.; Bartlett, R. O.

    1975-01-01

    Two 0.004 N thrust cesium bombardment ion thrustors have been developed and used for north-south stationkeeping in the geostationary Applications Technology Satellite-6 (ATS-6). The thrustor subsystems are mounted on the north and south faces of the earth viewing module such that 0.0026 N of thrust is applied normal to the orbit plane and 0.0036 N is applied radially upward. The change in the orbit inclination of the satellite is maintained at zero by operating the two thrustors alternately so that their thrust components, normal to the orbital plane, are symmetrically applied about the nodal crossings. Initial operation of the thrustors was successful. There was no interference with the satellite communications systems and the predicted spacecraft operating potential was verified. Subsequent trials failed due to a defect in the operation of the propellant reservoirs in zero g. A feed line valve is under development to correct this difficulty.

  13. Plasma properties in electron-bombardment ion thrusters

    SciTech Connect

    Matossian, J.N.; Beattie, J.R.

    1987-05-01

    The paper describes a technique for computing volume-averaged plasma properties within electron-bombardment ion thrusters, using spatially varying Langmuir-probe measurements. Average values of the electron densities are defined by integrating the spatially varying Maxwellian and primary electron densities over the ionization volume, and then dividing by the volume. Plasma properties obtained in the 30-cm-diameter J-series and ring-cusp thrusters are analyzed by the volume-averaging technique. The superior performance exhibited by the ring-cusp thruster is correlated with a higher average Maxwellian electron temperature. The ring-cusp thruster maintains the same fraction of primary electrons as does the J-series thruster, but at a much lower ion production cost. The volume-averaged predictions for both thrusters are compared with those of a detailed thruster performance model. 20 references.

  14. SPITZER EVIDENCE FOR A LATE-HEAVY BOMBARDMENT AND THE FORMATION OF UREILITES IN {eta} CORVI At {approx}1 Gyr

    SciTech Connect

    Lisse, C. M.; Wyatt, M. C.; Chen, C. H.; Morlok, A.; Watson, D. M.; Manoj, P.; Sheehan, P.; Currie, T. M.; Thebault, P.; Sitko, M. L. E-mail: wyatt@ast.cam.ac.uk E-mail: a.morlok@open.ac.uk E-mail: manoj@pas.rochester.edu E-mail: thayne.m.currie@nasa.gov E-mail: sitko@spacescience.org

    2012-03-10

    We have analyzed Spitzer and NASA/IRTF 2-35 {mu}m spectra of the warm, {approx}350 K circumstellar dust around the nearby MS star {eta} Corvi (F2V, 1.4 {+-} 0.3 Gyr). The spectra show clear evidence for warm, water- and carbon-rich dust at {approx}3 AU from the central star, in the system's terrestrial habitability zone. Spectral features due to ultra-primitive cometary material were found, in addition to features due to impact produced silica and high-temperature carbonaceous phases. At least 9 Multiplication-Sign 10{sup 18} kg of 0.1-100 {mu}m warm dust is present in a collisional equilibrium distribution with dn/da {approx} a{sup -3.5}, the equivalent of a 130 km radius Kuiper Belt object (KBO) of 1.0 g cm{sup 3} density and similar to recent estimates of the mass delivered to the Earth at 0.6-0.8 Gyr during the late-heavy bombardment. We conclude that the parent body was a Kuiper Belt body or bodies which captured a large amount of early primitive material in the first megayears of the system's lifetime and preserved it in deep freeze at {approx}150 AU. At {approx}1.4 Gyr they were prompted by dynamical stirring of their parent Kuiper Belt into spiraling into the inner system, eventually colliding at 5-10 km s{sup -1} with a rocky planetary body of mass {<=}M{sub Earth} at {approx}3 AU, delivering large amounts of water (>0.1% of M{sub Earth'sOceans}) and carbon-rich material. The Spitzer spectrum also closely matches spectra reported for the Ureilite meteorites of the Sudan Almahata Sitta fall in 2008, suggesting that one of the Ureilite parent bodies was a KBO.

  15. Spitzer Evidence for a Late Heavy Bombardment and the Formation of Urelites in {eta}Corvi at Approximately 1 Gyr

    NASA Technical Reports Server (NTRS)

    Lisse, C. M.; Wyatt, M. C.; Chen, C. H.; Morlok, A.; Watson, D. M.; Manj, P.; Sheehan, P.; Currie, T. M.; Thebault, P.; Sitko, M. L.

    2011-01-01

    We have analyzed Spitzer and NASA/IRTF 2 - 35 micrometer spectra of the warm, 350 K circumstellar dust around the nearby MS star eta Corvi (F2V, 1.4 plus or minus 0.3 Gyr). The spectra show clear evidence for warm, water- and carbon-rich dust at 3 AU from the central star, in the system's Terrestrial Habitability Zone. Spectral features due to ultra-primitive cometary material were found, in addition to features due to impact produced silica and high temperature carbonaceous phases. At least 9 x 10(exp 18) kg of 0.1 - 100 micrometer warm dust is present in a collisional equilibrium distribution with dn/da a(exp -3.5), the equivalent of a 130 km radius KBO of 1.0 grams per cubic centimeter density and similar to recent estimates of the mass delivered to the Earth at 0.6 - 0.8 Gyr during the Late Heavy Bombardment. We conclude that the parent body was a Kuiper-Belt body or bodies which captured a large amount of early primitive material in the first Myrs of the system's lifetime and preserved it in deep freeze at approximately 150 AU. At approximately 1.4 Gyr they were prompted by dynamical stirring of their parent Kuiper Belt into spiraling into the inner system, eventually colliding at 5-10 kilometers per second with a rocky planetary body of mass less than or equal to M(sub Earth at approximately 3 AU, delivering large amounts of water (greater than 0.1 % of M(sub Earth's Oceans)) and carbon-rich material. The Spitzer spectrum also closely matches spectra reported for the Ureilite meteorites of the Sudan Almahata Sitta fall in 2008, suggesting that one of the Ureilite parent bodies was a KBO.

  16. House-Dust Allergy

    PubMed Central

    Johnson, C. A.

    1982-01-01

    House-dust allergy is a common cause of perennial allergic rhinitis and extrinsic asthma. Symptoms tend to be worse when the patient is in bed. A positive skin test properly performed and interpreted confirms the diagnosis. The house-dust mite is the most important antigenic component of house-dust. Treatment consists of environmental control directed at reducing the mite content of bedroom dust, plus control of symptoms with drugs. Immunotherapy is controversial. ImagesFig. 1 PMID:21286201

  17. Spectrophotometry of Dust in Comet Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Witteborn, Fred C. (Technical Monitor)

    1997-01-01

    Comets, such as Hale-Bopp (C/1995 O1), are frozen reservoirs of primitive solar nebula dust grains and ices. Analysis of the composition of cometary dust grains from infrared spectroscopic techniques permits an estimation of the types of organic and inorganic materials that constituted the early primitive solar nebula. In addition, the cometary bombardment of the Earth (approximately 3.5 Gy ago) supplied the water for the oceans and brought organic materials to Earth which may have been biogenic. Spectroscopic observations of comet Hale-Bopp suggest the possible presence of organic hydrocarbon species, silicate and olivine dust grains, and water ice. Spectroscopy near 3 microns obtained in Nov 1996 r=2.393 AU, delta=3.034 AU) shows a feature which we attribute to PAH emission. The spatial morphology of the 3.28 microns PAH feature is also presented. Optical and infrared spectrophotometric observations of comets convey valuable information about the spatial distribution and properties of dust and gas within the inner coma. In the optical and NIR shortward of 2 microns, the observed light is primarily scattered sunlight from the dust grains. At longer wavelengths, particularly in the 10 gm window, thermal emission from these grains dominates the radiation allowing an accurate estimate of grain sizes and chemical composition. Here we present an initial analysis of spectra taken with the NASA HIFOGS at 7-14 microns as part of a multiwavelength temporal study of the "comet of the century".

  18. China Dust and Sand

    Atmospheric Science Data Center

    2013-04-16

    ... article title:  Dust and Sand Sweep Over Northeast China     View Larger Image ... these views of the dust and sand that swept over northeast China on March 10, 2004. Information on the height of the dust and an ...

  19. Middle East Dust

    Atmospheric Science Data Center

    2013-04-16

    ... only some of the dust over eastern Syria and southeastern Turkey can be discerned. The dust is much more obvious in the center panel, ... 18, 2002 - A large dust plume extends across Syria and Turkey. project:  MISR category:  gallery ...

  20. Dust in the Universe

    ERIC Educational Resources Information Center

    Hemenway, Mary Kay; Armosky, Brad J.

    2004-01-01

    Space is seeming less and less like empty space as new discoveries and reexaminations fill in the gaps. And, ingenuity and technology, like the Spitzer Space Telescope, is allowing examination of the far reaches of the Milky Way and beyond. Even dust is getting its due, but not the dust everyone is familiar with. People seldom consider the dust in…

  1. Niamey Dust Observations

    DOE Data Explorer

    Flynn, Connor

    2008-10-01

    Niamey aerosol are composed of two main components: dust due to the proximity of the Sahara Desert, and soot from local and regional biomass burning. The purpose of this data product is to identify when the local conditions are dominated by the dust component so that the properties of the dust events can be further studied.

  2. Significant enhancement of negative secondary ion yields by cluster ion bombardment combined with cesium flooding.

    PubMed

    Philipp, Patrick; Angerer, Tina B; Sämfors, Sanna; Blenkinsopp, Paul; Fletcher, John S; Wirtz, Tom

    2015-10-01

    In secondary ion mass spectrometry (SIMS), the beneficial effect of cesium implantation or flooding on the enhancement of negative secondary ion yields has been investigated in detail for various semiconductor and metal samples. All results have been obtained for monatomic ion bombardment. Recent progress in SIMS is based to a large extent on the development and use of cluster primary ions. In this work we show that the enhancement of negative secondary ions induced by the combination of ion bombardment with simultaneous cesium flooding is valid not only for monatomic ion bombardment but also for cluster primary ions. Experiments carried out using C60+ and Ar4000+ bombardment on silicon show that yields of negative secondary silicon ions can be optimized in the same way as by Ga+ and Cs+ bombardment. Both for monatomic and cluster ion bombardment, the optimization does not depend on the primary ion species. Hence, it can be assumed that the silicon results are also valid for other cluster primary ions and that results obtained for monatomic ion bombardment on other semiconductor and metal samples are also valid for cluster ion bombardment. In SIMS, cluster primary ions are also largely used for the analysis of organic matter. For polycarbonate, our results show that Ar4000+ bombardment combined with cesium flooding enhances secondary ion signals by a factor of 6. This can be attributed to the removal of charging effects and/or reduced fragmentation, but no major influence on ionization processes can be observed. The use of cesium flooding for the imaging of cells was also investigated and a significant enhancement of secondary ion yields was observed. Hence, cesium flooding has also a vast potential for SIMS analyses with cluster ion bombardment. PMID:26378890

  3. 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.

  4. Comparative analysis of the optical spectra of the holmium atom excited by electron impact and ionic bombardment

    SciTech Connect

    Vasileva, E.K.; Morozov, S.N.; Ryskin, B.V.

    1988-02-01

    A comparative analysis of the optical spectra of holmium excited by electron impact and ionic bombardment is given. It is shown that under ionic bombardment, the probability of excitation of screened transitions is significantly higher than under electron impact.

  5. Interstellar Dust Instrumentation

    NASA Astrophysics Data System (ADS)

    Sternovsky, Zoltan; Gruen, E.; Horanyi, M.; Drake, K.; Collette, A.; Kempf, S.; Srama, R.; Postberg, F.; Krueger, H.; Auer, S.

    2010-10-01

    Interstellar grains traversing the inner planetary system have been identified by the Ulysses dust detector. Space dust detectors on other missions confirmed this finding. Analysis of the Stardust collectors is under way to search for and analyze such exotic grains. Interstellar dust particles can be detected and analyzed in the near-Earth space environment. New instrumentation has been developed to determine the origin of dust particles and their elemental composition. A Dust Telescope is a combination of a Dust Trajectory Sensor (DTS, Rev. Sci. Instrum. 79, 084501, 2008) together with a high mass resolution mass analyzer for the chemical composition of dust particles in space. Dust particles' trajectories are determined by the measurement of induced electric signals when a charged grain flies through a position sensitive electrode system. A modern DTS can measure dust particles as small as 0.2 micron in radius and dust speeds up to 100 km/s. Large area chemical analyzers of 0.1 m2 sensitive area have been tested at a dust accelerator and it was demonstrated that they have sufficient mass resolution to resolve ions with atomic mass number up to >100 (Earth, Moon and Planets, DOI: 10.1007/s11038-005-9040-z, 2005; Rev. Sci. Instrum. 78, 014501, 2007). The advanced Dust Telescope is capable of identifying interstellar and interplanetary grains, and measuring their mass, velocity vector, charge, elemental and isotopic compositions. An Active Dust Collector combines a DTS with an aerogel or other dust collector materials, e.g. like the ones used on the Stardust mission. The combination of a DTS with a dust collector provides not only individual trajectories of the collected particles but also their impact time and position on the collector which proves essential in finding collected sub-micron sized grains on the collector.

  6. Dust Delivery from Enceladus to the Moons of Saturn

    NASA Astrophysics Data System (ADS)

    Juhasz, A.; Horanyi, M.

    2015-12-01

    The active geysers in the south polar region of Enceladus are sources of dust particles that sustain the vast E-ring of Saturn, extending out beyond Titan at 20 Saturn radii. The dynamics of the small micron and submicron particles escaping from Enceladus is primarily set by Saturn's gravity, plasma drag, radiation pressure and electromagnetic forces.This presentation will summarize our recently developed simulations to follow a large number of dust particles from Enceladus till their ultimate demise: being ejected from Saturn's magnetosphere, or hitting one of its moons. We will describe the expected size, speed and spatial distributions of the impacting particles and identify their predicted anisotropies bombarding the leading/trailing hemispheres of the moons, possibly offering an explanation for their observed brightness features.

  7. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  8. Lunar Airborne Dust Toxicity Hazard Assessments (Invited)

    NASA Astrophysics Data System (ADS)

    Cooper, B. L.; McKay, D. S.; Taylor, L. A.; Wallace, W. T.; James, J.; Riofrio, L.; Gonzalez, C. P.

    2009-12-01

    The Lunar Airborne Dust Toxicity Assessment Group (LADTAG) is developing data to set the permissible limits for human exposure to lunar dust. This standard will guide the design of airlocks and ports for EVA, as well as the requirements for filtering and monitoring the atmosphere in habitable vehicles, rovers and other modules. LADTAG’s recommendation for permissible exposure limits will be delivered to the Constellation Program in late 2010. The current worst-case exposure limit of 0.05 mg/m3, estimated by LADTAG in 2006, reflects the concern that lunar dust may be as toxic as quartz dust. Freshly-ground quartz is known to be more toxic than un-ground quartz dust. Our research has shown that the surfaces of lunar soil grains can be more readily activated by grinding than quartz. Activation was measured by the amount of free radicals generated—activated simulants generate Reactive Oxygen Species (ROS) i.e., production of hydroxyl free radicals. Of the various influences in the lunar environment, micrometeorite bombardment probably creates the most long-lasting reactivity on the surfaces of grains, although solar wind impingement and short-wavelength UV radiation also contribute. The comminution process creates fractured surfaces with unsatisfied bonds. When these grains are inhaled and carried into the lungs, they will react with lung surfactant and cells, potentially causing tissue damage and disease. Tests on lunar simulants have shown that dissolution and leaching of metals can occur when the grains are exposed to water—the primary component of lung fluid. However, simulants may behave differently than actual lunar soils. Rodent toxicity testing will be done using the respirable fraction of actual lunar soils (particles with physical size of less than 2.5 micrometers). We are currently separating the fine material from the coarser material that comprises >95% of the mass of each soil sample. Dry sieving is not practical in this size range, so a new system

  9. Interstellar Dust - A Review

    NASA Technical Reports Server (NTRS)

    Salama, Farid

    2012-01-01

    The study of the formation and the destruction processes of cosmic dust is essential to understand and to quantify the budget of extraterrestrial organic materials. Although dust with all its components plays an important role in the evolution of interstellar physics and chemistry and in the formation of organic materials, little is known on the formation and destruction processes of carbonaceous dust. Laboratory experiments that are performed under conditions that simulate interstellar and circumstellar environments to provide information on the nature, the size and the structure of interstellar dust particles, the growth and the destruction processes of interstellar dust and the resulting budget of extraterrestrial organic molecules. A review of the properties of dust and of the laboratory experiments that are conducted to study the formation processes of dust grains from molecular precursors will be given.

  10. Light Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    14 October 2004 Many Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images exhibit wild patterns of dark streaks thought to have formed by the passage of many dust devils. The dust devils disrupt the dust coating the martian surface, leaving behind a streak. However, not all dust devils make streaks, and not all dust devil streaks are dark. Some are light---it simply depends upon which is darker, the substrate or the dust that the spinning vortex disrupts. The example of light-toned dust devil streaks shown here is located in southern Schiaparelli Basin near 5.3oS, 343.3oW. The image covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the left/upper left.

  11. 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.

  12. 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.

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

    SciTech Connect

    Samela, Juha; Nordlund, Kai

    2010-02-01

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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Samela, Juha; Nordlund, Kai

    2010-02-01

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

  16. 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.

  17. 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.

  18. 3D laser scanning microscopy of hypervelocity impact features in metal and aerogel targets

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

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

    NASA Technical Reports Server (NTRS)

    Howe, John T.; Yang, Lily

    1991-01-01

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

  20. 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.

  1. 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.

  2. Windblown fugitive dust emissions from smelter slag

    NASA Astrophysics Data System (ADS)

    Sanderson, R. Steven; McKenna Neuman, Cheryl; Boulton, J. Wayne

    2014-06-01

    The waste products of mining and smelter operations contain fine particles that, when stored in stockpiles and tailings ponds, are subject to aerodynamic forces that may result in their suspension and transport within boundary layer air flows. The accuracy of atmospheric dispersion models such as AERMOD depends strongly upon suitable inputs for the emission rate that generally must be either measured or estimated from suitable analogues. Measurements of the emission rate of PM10 from smelter slag, based on wind tunnel experiments using the control volume method, are reported in this study and compared with vertical flux values obtained using a finite difference approximation. As compared to natural soils, the dust coatings on slag fragments are rapidly depleted during wind events so that the temporal aspect is important to capture in any consideration of the emission rate. At low wind speeds, vertical flux measurements underestimate the emission rate, but otherwise the agreement is excellent. Comparison with field measurements obtained at the smelter site reveals a degree of overlap with the laboratory data. As a general rule, PM10 emission from smelter slag by aerodynamic entrainment alone is several orders of magnitude lower than published fluxes of total suspended particulate (TSP) emitted from natural soil surfaces for which saltation bombardment is recognized to play a key role in the ejection of dust.

  3. Effect of nitrogen atomic percentage on N+-bombarded MWCNTs in cytocompatibility and hemocompatibility

    PubMed Central

    2014-01-01

    N+-bombarded multi-walled carbon nanotubes (N+-bombarded MWCNTs), with different nitrogen atomic percentages, were achieved by different N ion beam currents using ion beam-assisted deposition (IBAD) on MWCNTs synthesized by chemical vapor deposition (CVD). Characterizations of N+-bombarded MWCNTs were evaluated by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and contact angle. For comparison, the in vitro cytocompatibility of the N+-bombarded MWCNTs with different N atomic percentages was assessed by cellular adhesion investigation using human endothelial cells (EAHY926) and mouse fibroblast cells (L929), respectively. The results showed that the presence of nitrogen in MWCNTs accelerated cell growth and proliferation of cell culture. The higher nitrogen content of N+-bombarded MWCNTs, the better cytocompatibility. In addition, N+-bombarded MWCNTs with higher N atomic percentage displayed lower platelet adhesion rate. No hemolysis can be observed on the surfaces. These results proved that higher N atomic percentage led N+-bombarded MWCNTs to better hemocompatibility. PMID:24666845

  4. Erosion of frozen sulfur dioxide by ion bombardment - Applications to Io

    NASA Astrophysics Data System (ADS)

    Melcher, C. L.; Lepoire, D. J.; Cooper, B. H.; Tombrello, T. A.

    1982-10-01

    The erosion of frozen SO2 due to bombardment by both light and heavy ions (He and F) was measured for bombarding energies of 0.08 to 1.3 MeV/amu. The number of SO2 molecules ejected from the target per incident ion (i.e., the sputtering yield) was 50 for 1.5 MeV He ions and 7300 for 6 MeV F ions. Ion bombardment followed by heating produced an oxygen/sulfur residue which was much more stable against subsequent ion bombardment than the initial frozen SO2. The erosion rate of SO2 frost on Jupiter's moon Io depends strongly on the elemental composition and energy spectra of the magnetospheric ion flux which bombards the surface. The combined effects of ion bombardment and heating which produced residues on the target substrates may also occur on Io from magnetospheric ion bombardment and heating by volcanism. The experimental results compare favorably with a new model of the sputtering process which considers the energy loss of the incident ion to electronic excitation in the target.

  5. Effect of nitrogen atomic percentage on N+-bombarded MWCNTs in cytocompatibility and hemocompatibility.

    PubMed

    Zhao, Mengli; Cao, Ye; Liu, Xiaoqi; Deng, Jianhua; Li, Dejun; Gu, Hanqing

    2014-01-01

    N+-bombarded multi-walled carbon nanotubes (N+-bombarded MWCNTs), with different nitrogen atomic percentages, were achieved by different N ion beam currents using ion beam-assisted deposition (IBAD) on MWCNTs synthesized by chemical vapor deposition (CVD). Characterizations of N+-bombarded MWCNTs were evaluated by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and contact angle. For comparison, the in vitro cytocompatibility of the N+-bombarded MWCNTs with different N atomic percentages was assessed by cellular adhesion investigation using human endothelial cells (EAHY926) and mouse fibroblast cells (L929), respectively. The results showed that the presence of nitrogen in MWCNTs accelerated cell growth and proliferation of cell culture. The higher nitrogen content of N+-bombarded MWCNTs, the better cytocompatibility. In addition, N+-bombarded MWCNTs with higher N atomic percentage displayed lower platelet adhesion rate. No hemolysis can be observed on the surfaces. These results proved that higher N atomic percentage led N+-bombarded MWCNTs to better hemocompatibility. PMID:24666845

  6. An Analytical Model for the Dust Environment around Saturn's Moons Pallene, Methone and Anthe

    NASA Astrophysics Data System (ADS)

    Seiler, M.; Seiß, M.; Sun, K.-L.; Spahn, F.

    2014-04-01

    Since its arrival at Saturn in 2004 the observations by the spacecraft Cassini have revolutionised the understanding of the dynamics in planetary rings. By analysing Cassini images, Hedman et al. [1] detected faint dust along the orbits of Saturn's tiny moons Methone, Anthe and Pallene. While the ring material around Methone and Anthe appears to be longitudinally confined to arcs, a continuous ring of material has been observed around the orbit of Pallene by the Cassini dust analyzer. The data show, that at least part of the torus lies exterior Pallene's orbit. Many tiny moons are located between Mimas and Enceladus and are known to be resonantly perturbed by these [2, 3]. In this work, we will present an analytical model to describe the particle density of the dust environment around Pallene, Methone and Anthe and to explain a radially outward shift of the dust torus. We assume the dust torus to originate from particles, which are ejected from the surface of the moon by micrometeroidal bombardment. We concentrate on the interaction of the dust particles with corotational resonances and plasma drag, where the plasma drag limits the life time of the dust particles within the resonances. Additionally, in order to describe the extension of the dust torus, we include the effect of radiation pressure, Lorentz force and planetary oblateness.

  7. The origin and evolution of the Uranian dust rings

    SciTech Connect

    Colwell, J.E.

    1989-01-01

    The numerous dust bands discovered by Voyager 2 at Uranus have lifetimes on the order of 100 years against orbital decay by exospheric drag. A system of low optical depth rings of 10 meter to 1 km sized bodies (moonlet belts) are proposed as continuing sources of the dust particles. The ring system is modeled as a Markov Chain consisting of states through which dust particle evolve with time. Physical processes included in the model are orbit decay by exospheric drag and Poynting-Robertson light drag; destruction of grains by meteoroid impact; transport of dust through the classical rings and moonlet belts; creation of dust particles from meteoroid impacts onto rings, moons, and moonlet belts; liberation of regolith material through ring and moonlet belt particle collisions; and sweepup of ejecta by ring and moonlet belt particles. The optical depth profiles for the main rings from Voyager 2 Photopolarimeter Subsystem (PPS) occultation observation are used in modeling the transport of dust through the rings. Simulations of the Uranus ring system show that this model reproduces the observed characteristics of the Uranus dust rings. The moonlet belt model is applied to the rings of Jupiter, Saturn, and Neptune, and is capable of reproducing some of the observed characteristics of those ring systems. The moonlet belt objects fit on a collisionally derived power-law size distribution with the other components of the ring moon systems. Since the rings and moonlet belts have lifetimes due to viscous spreading less than the age of the solar system, a net model of planetary rings emerges in which the rings are continually created from the disruption of small satellites by meteoroid bombardment.

  8. Compositional Evolution of Saturn's Rings Due to Meteoroid Bombardment

    NASA Technical Reports Server (NTRS)

    Cuzzi, J.; Estrada, P.; Young, Richard E. (Technical Monitor)

    1997-01-01

    In this paper we address the question of compositional evolution in planetary ring systems subsequent to meteoroid bombardment. The huge surface area to mass ratio of planetary rings ensures that this is an important process, even with current uncertainties on the meteoroid flux. We develop a new model which includes both direct deposition of extrinsic meteoritic "pollutants", and ballistic transport of the increasingly polluted ring material as impact ejecta. Our study includes detailed radiative transfer modeling of ring particle spectral reflectivities based on refractive indices of realistic constituents. Voyager data have shown that the lower optical depth regions in Saturn's rings (the C ring and Cassini Division) have darker and less red particles than the optically thicken A and B rings. These coupled structural-compositional groupings have never been explained; we present and explore the hypothesis that global scale color and compositional differences in the main rings of Saturn arise naturally from extrinsic meteoroid bombardment of a ring system which was initially composed primarily, but not entirely, of water ice. We find that the regional color and albedo differences can be understood if all ring material was initially identical (primarily water ice, based on other data, but colored by tiny amounts of intrinsic reddish, plausibly organic, absorber) and then evolved entirely by addition and mixing of extrinsic, nearly neutrally colored. plausibly carbonaceous material. We further demonstrate that the detailed radial profile of color across the abrupt B ring - C ring boundary can.constrain key unknown parameters in the model. Using new alternates of parameter values, we estimate the duration of the exposure to extrinsic meteoroid flux of this part of the rings, at least, to be on the order of 10(exp 8) years. This conclusion is easily extended by inference to the Cassini Division and its surroundings as well. This geologically young "age" is compatible

  9. Electron-beam-deposited thin polymer films - Electrical properties vs bombarding current.

    NASA Technical Reports Server (NTRS)

    Babcock, L. E.; Christy, R. W.

    1972-01-01

    Polymer films about 150 A thick, deposited on glass substrates by electron bombardment of tetramethyltetraphenyltrisiloxane, were studied, after being sandwiched between evaporated aluminum electrodes, the top one semitransparent. The capacitance, conductance, and photoconductance of the sandwiches were measured at room temperature as a function of the electron bombarding current which formed the polymer. The polymer thickness was obtained independently from Christy's (1960) empirical formula for the rate of formation. The obtained results indicate that, with increasing bombarding current, the polymer undergoes an increase in both crosslinking bonds and dangling bonds. Exposure to air drastically reduces the density of dangling bonds, but does not affect the crosslinking.

  10. Changes in a surface of polycrystalline aluminum upon bombardment with argon ions

    NASA Astrophysics Data System (ADS)

    Ashkhotov, O. G.; Ashkhotova, I. B.; Bliev, A. P.; Magkoev, T. T.; Krymshokalova, D. A.

    2014-10-01

    The interaction between argon ions and a natural oxide layer of polycrystalline aluminum is studied via Auger electron (AE) and electron energy loss (EEL) spectroscopy. It is found that bombardment with argon ions whose energy is lower than the Al2O3 sputtering threshold results in the accumulation of bombarding ions in interstitial surface voids, thus forming a supersaturated solid solution of target atoms and bombarding ions of argon and nitrogen entrapped by the ion beam from the residual gas of the working chamber of the spectrometer.

  11. Haul road dust control

    SciTech Connect

    Reed, W.R.; Organiscak, J.A.

    2007-10-15

    A field study was conducted to measure dust from haul trucks at a limestone quarry and a coal preparation plant waste hauling operation. The study found that primarily wind, distance and road treatment conditions notably affected the dust concentrations at locations next to, 50 ft from, and 100 ft away from the unpaved haulage road. Airborne dust measured along the unpaved haul road showed that high concentrations of fugitive dust can be generated with these concentrations rapidly decreasing to nearly background levels within 100 ft of the road. Instantaneous respirable dust measurements illustrated that the trucks generate a real-time dust cloud that has a peak concentration with a time-related decay rate as the dust moves past the sampling locations. The respirable dust concentrations and peak levels were notably diminished as the dust cloud was transported, diluted, and diffused by the wind over the 100 ft distance from the road. Individual truck concentrations and peak levels measured next to the dry road surface test section were quite variable and dependent on wind conditions, particularly wind direction, with respect to reaching the sampling location. The vast majority of the fugitive airborne dust generated from unpaved and untreated haulage roads was non-respirable. 6 figs.

  12. Compact Electron Gun Based on Secondary Emission Through Ionic Bombardment

    PubMed Central

    Diop, Babacar; Bonnet, Jean; Schmid, Thomas; Mohamed, Ajmal

    2011-01-01

    We present a new compact electron gun based on the secondary emission through ionic bombardment principle. The driving parameters to develop such a gun are to obtain a quite small electron gun for an in-flight instrument performing Electron Beam Fluorescence measurements (EBF) on board of a reentry vehicle in the upper atmosphere. These measurements are useful to characterize the gas flow around the vehicle in terms of gas chemical composition, temperatures and velocity of the flow which usually presents thermo-chemical non-equilibrium. Such an instrument can also be employed to characterize the upper atmosphere if placed on another carrier like a balloon. In ground facilities, it appears as a more practical tool to characterize flows in wind tunnel studies or as an alternative to complex electron guns in industrial processes requiring an electron beam. We describe in this paper the gun which has been developed as well as its different features which have been characterized in the laboratory. PMID:22163896

  13. Fast atom bombardment tandem mass spectrometry of carotenoids

    SciTech Connect

    van Breeman, R.B.; Schmitz, H.H.; Schwartz, S.J.

    1995-02-01

    Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

  14. Comet impacts and chemical evolution on the bombarded earth

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Aggarwal, Hans

    1992-01-01

    Amino acids yields for previously published shock tube experiments are used with minimum Cretaceous-Tertiary (K/T) impactor mass and comet composition to predict AIB amino acid K/T boundary sediment column density. The inferred initial concentration of all amino acids in the K/T sea and in similar primordial seas just after 10 km comet impacts would have been at least 10 exp -7 M. However, sinks for amino acids must also be considered in calculating amino acid concentrations after comet impacts and in assessing the contribution of comets to the origin of life. The changing concentration of cometary amino acids due to ultraviolet light is compared with the equilibrium concentration of amino acids produced in the sea from corona discharge in the atmosphere, deposition in water, and degradation by ultraviolet light. Comets could have been more important than endogenous agents for initial evolution of amino acids. Sites favorable for chemical evolution of amino acids are examined, and it is concluded that chemical evolution could have occurred at or above the surface even during periods of intense bombardment of earth before 3.8 billion years ago.

  15. Actinide production from xenon bombardments of curium-248

    SciTech Connect

    Welch, R.B.

    1985-01-01

    Production cross sections for many actinide nuclides formed in the reaction of /sup 129/Xe and /sup 132/Xe with /sup 248/Cm at bombarding energies slightly above the coulomb barrier were determined using radiochemical techniques to isolate these products. These results are compared with cross sections from a /sup 136/Xe + /sup 248/Cm reaction at a similar energy. When compared to the reaction with /sup 136/Xe, the maxima in the production cross section distributions from the more neutron deficient projectiles are shifted to smaller mass numbers, and the total cross section increases for the production of elements with atomic numbers greater than that of the target, and decreases for lighter elements. These results can be explained by use of a potential energy surface (PES) which illustrates the effect of the available energy on the transfer of nucleons and describes the evolution of the di-nuclear complex, an essential feature of deep-inelastic reactions (DIR), during the interaction. The other principal reaction mechanism is the quasi-elastic transfer (QE). Analysis of data from a similar set of reactions, /sup 129/Xe, /sup 132/Xe, and /sup 136/Xe with /sup 197/Au, aids in explaining the features of the Xe + Cm product distributions, which are additionally affected by the depletion of actinide product yields due to deexcitation by fission. The PES is shown to be a useful tool to predict the general features of product distributions from heavy ion reactions.

  16. Effect of argon ion bombardment on amorphous silicon carbonitride films

    NASA Astrophysics Data System (ADS)

    Batocki, R. G. S.; Mota, R. P.; Honda, R. Y.; Santos, D. C. R.

    2014-04-01

    Amorphous silicon carbonitride (a-SiCN:H) films were synthesized by radiofrequency (RF) Plasma Enhanced Vapor Chemical Deposition (PECVD) using hexamethyldisilazane (HMDSN) as precursor compound. Then, the films were post-treated by Plasma Immersion Ion Implantation (PIII) in argon atmosphere from 15 to 60 min. The hardness of the film enhanced after ion implantation, and the sample treated at 45 min process showed hardness greater than sixfold that of the untreated sample. This result is explained by the crosslinking and densification of the structure. Films were exposed to oxygen plasma for determining of the etching rate. It decreased monotonically from 33 Å/min to 19 Å/min for the range of process time, confirming structural alterations. Hydrophobic character of the a-SiCN:H films were modified immediately after ion bombardment, due to incorporation of polar groups. However, the high wettability of the films acquired by the ion implantation was diminished after aging in air. Therefore, argon PIII made a-SiCN:H films mechanically more resistant and altered their hydrophobic character.

  17. 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.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

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

  20. 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.

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

    PubMed

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

    2015-04-01

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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

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

    SciTech Connect

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

    1980-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    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.

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  14. 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.

  15. 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.

  16. DUST FORMATION IN MACRONOVAE

    SciTech Connect

    Takami, Hajime; Ioka, Kunihito; Nozawa, Takaya E-mail: kunihito.ioka@kek.jp

    2014-07-01

    We examine dust formation in macronovae (as known as kilonovae), which are the bright ejecta of neutron star binary mergers and one of the leading sites of r-process nucleosynthesis. In light of information about the first macronova candidate associated with GRB 130603B, we find that dust grains of r-process elements have difficulty forming because of the low number density of the r-process atoms, while carbon or elements lighter than iron can condense into dust if they are abundant. Dust grains absorb emission from ejecta with an opacity even greater than that of the r-process elements, and re-emit photons at infrared wavelengths. Such dust emission can potentially account for macronovae without r-process nucleosynthesis as an alternative model. This dust scenario predicts a spectrum with fewer features than the r-process model and day-scale optical-to-ultraviolet emission.

  17. Bright Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    9 June 2004 Martian dust devils sometimes disrupt thin coatings of surface dust to create dark streak patterns on the surface. However, not all dust devils make streaks, and not all dust devil streaks are dark. In Syria Planum, the streaks are lighter than the surrounding plains. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows an example from Syria near 8.8oS, 103.6oW. The thin coating of surface dust in this region is darker than the substrate beneath it. This is fairly unusual for Mars, because most dust is bright. This image covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the left/lower left.

  18. Dust particles investigation for future Russian lunar missions.

    NASA Astrophysics Data System (ADS)

    Dolnikov, Gennady; Horanyi, Mihaly; Esposito, Francesca; Zakharov, Alexander; Popel, Sergey; Afonin, Valeri; Borisov, Nikolay; Seran, Elena; Godefroy, Michel; Shashkova, Inna; Kuznetsov, Ilya; Lyash, Andrey; Vorobyova, Elena; Petrov, Oleg; Lisin, Evgeny

    One of the complicating factors of the future robotic and human lunar landing missions is the influence of the dust. Meteorites bombardment has accompanied by shock-explosive phenomena, disintegration and mix of the lunar soil in depth and on area simultaneously. As a consequence, the lunar soil has undergone melting, physical and chemical transformations. Recently we have the some reemergence for interest of Moon investigation. The prospects in current century declare USA, China, India, and European Union. In Russia also prepare two missions: Luna-Glob and Luna-Resource. Not last part of investigation of Moon surface is reviewing the dust condition near the ground of landers. Studying the properties of lunar dust is important both for scientific purposes to investigation the lunar exosphere component and for the technical safety of lunar robotic and manned missions. The absence of an atmosphere on the Moon's surface is leading to greater compaction and sintering. Properties of regolith and dust particles (density, temperature, composition, etc.) as well as near-surface lunar exosphere depend on solar activity, lunar local time and position of the Moon relative to the Earth's magneto tail. Upper layers of regolith are an insulator, which is charging as a result of solar UV radiation and the constant bombardment of charged particles, creates a charge distribution on the surface of the moon: positive on the illuminated side and negative on the night side. Charge distribution depends on the local lunar time, latitude and the electrical properties of the regolith (the presence of water in the regolith can influence the local distribution of charge). On light side of Moon near surface layer there exists possibility formation dusty plasma system. Altitude of levitation is depending from size of dust particle and Moon latitude. The distribution dust particle by size and altitude has estimated with taking into account photoelectrons, electrons and ions of solar wind, solar

  19. Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 8 May 2002) The Science This image, centered near 50.0 S and 17.7 W displays dust devil tracks on the surface. Most of the lighter portions of the image likely have a thin veneer of dust settled on the surface. As a dust devil passes over the surface, it acts as a vacuum and picks up the dust, leaving the darker substrate exposed. In this image there is a general trend of many of the tracks running from east to west or west to east, indicating the general wind direction. There is often no general trend present in dust devil tracks seen in other images. The track patterns are quite ephemeral and can completely change or even disappear over the course of a few months. Dust devils are one of the mechanisms that Mars uses to constantly pump dust into the ubiquitously dusty atmosphere. This atmospheric dust is one of the main driving forces of the present Martian climate. The Story Vrrrrooooooooom. Think of a tornado, the cartoon Tasmanian devil, or any number of vacuum commercials that powerfully suck up swirls of dust and dirt. That's pretty much what it's like on the surface of Mars a lot of the time. Whirlpools of wind called

  20. Cometary dust composition

    NASA Technical Reports Server (NTRS)

    Gehrz, R. D.; Hanner, M. S.

    1988-01-01

    The earth based measurements and in situ sampling of Comet Halley have provided new data about the chemical composition of cometary grains. Recent progress in laboratory studies of interplanetary dust particles (IDPs) complement the comet data, allowing inferences about the mineralogy and physical structure of the comet dust to be drawn from the observed elemental composition and infrared spectra. The in situ dust composition measurements at Halley, the composition of IDPs and their relation to comet dust, and the origin of the 3.4 micron hydrocarbon feature is discussed. Related discussion is also presented on aromatic components in comets and the 3.4 micron feature. These topics are briefly summarized.

  1. Operational Dust Prediction

    NASA Technical Reports Server (NTRS)

    Benedetti, Angela; Baldasano, Jose M.; Basart, Sara; Benincasa, Francesco; Boucher, Olivier; Brooks, Malcolm E.; Chen, Jen-Ping; Colarco, Peter R.; Gong, Sunlin; Huneeus, Nicolas; Jones, Luke; Lu, Sarah; Menut, Laurent; Morcrette, Jean-Jacques; Mulcahy, Jane; Nickovic, Slobodan; Garcia-Pando, Carlos P.; Reid, Jeffrey S.; Sekiyama, Thomas T.; Tanaka, Taichu Y.; Terradellas, Enric; Westphal, Douglas L.; Zhang, Xiao-Ye; Zhou, Chun-Hong

    2014-01-01

    Over the last few years, numerical prediction of dust aerosol concentration has become prominent at several research and operational weather centres due to growing interest from diverse stakeholders, such as solar energy plant managers, health professionals, aviation and military authorities and policymakers. Dust prediction in numerical weather prediction-type models faces a number of challenges owing to the complexity of the system. At the centre of the problem is the vast range of scales required to fully account for all of the physical processes related to dust. Another limiting factor is the paucity of suitable dust observations available for model, evaluation and assimilation. This chapter discusses in detail numerical prediction of dust with examples from systems that are currently providing dust forecasts in near real-time or are part of international efforts to establish daily provision of dust forecasts based on multi-model ensembles. The various models are introduced and described along with an overview on the importance of dust prediction activities and a historical perspective. Assimilation and evaluation aspects in dust prediction are also discussed.

  2. Ion bombardment and its effects on the optical properties of metals

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1964-01-01

    An experimental program, to evaluate the change in total hemispherical emittance and solar absorptance of engineering metals used on spacecraft and in spacecraft instrumentation systems, is presented. Three materials, titanium alloy, pure aluminum, and electrolytic copper, were used in the experiment. Results show that emittance, absorptance, and alpha/epsilon ratio of the materials were changed by ion bombardment. The time before the change occurs depends upon the material used, the intensity of bombardment, and the environment assumed.

  3. Particle-In-Cell/Monte Carlo Simulation of Ion Back Bombardment in Photoinjectors

    SciTech Connect

    Qiang, Ji; Corlett, John; Staples, John

    2009-03-02

    In this paper, we report on studies of ion back bombardment in high average current dc and rf photoinjectors using a particle-in-cell/Monte Carlo method. Using H{sub 2} ion as an example, we observed that the ion density and energy deposition on the photocathode in rf guns are order of magnitude lower than that in a dc gun. A higher rf frequency helps mitigate the ion back bombardment of the cathode in rf guns.

  4. Ne +, Ar + and Xe + ion bombardment induced and suppressed topography on Si

    NASA Astrophysics Data System (ADS)

    Vishnyakov, V.; Carter, G.

    1995-12-01

    The topographic evolution of Si irradiated at room temperature with Ne +, Ar + and Xe + ions in the energy range 5-40 keV at 45° to the substrate normal at high ion fluences has been studied. Other than isolated etch pits no topography results from Ne + bombardment at all energies or from Ar + bombardment at 5 and 10 keV. Ar + bombardment at 20 keV, however, initially produces transverse low-amplitude waves which transform, with increasing erosion, into larger amplitude corrugated and facetted wavelike structures. The present data do not conform to existing model predictions but do suggest that, technically, light low energy gas ions can be used to inhibit roughening during sputtering erosion. Xe + ion bombardment, on the other hand, produces clearly-defined transverse wave structures on the surface, which are inimical to sputter-profiling applications. However, Xe + bombardment-induced morphology, when exposed to further 20 keV Ne + or 10 keV Ar + bombardment loses its rippled habit, indicating that such irradiation can be employed to cure the deleterious roughening processes as well as inhibit roughening.

  5. Large Area Dust Detector onboard Solar Power Sail Spacecraft

    NASA Astrophysics Data System (ADS)

    Yano, Hajime

    JAXA is aiming to launch the solar power sail engineering demonstrator to the outer planet region of the solar system like Jupiter and the Jovian Trojan asteroids in 2010's. Its interplanetary cruise is a relevant and rare opportunity to monitor physical properties that may be varied by heliocentric distances continuously such as solar wind, solar magnetosphere and micrometeoroid flux. We have been developing the largest but still light-weight dust detector ever to be onboard deep space probes since 2000. PVDF films of a few to 10's of micron thickness are attached as a small part of the solar sail membrane to count and time hypervelocity impacts by micrometeoroids larger than micron size. The first spaceflight test of this dust detector in the order of 100 cm2 detection area was conducted onboard SSSAT (Solar Sail Satellite) as the M-V sub-payload launched to LEO in September 2006. The second opportunity of this series will be the 4- channel impact sensors onboard Kagayaki nano-satellite as an H-IIA piggyback to be launched in 2008. Actual interplanetary measurements can be achieved by the Small Solar Power Sail Demonstrator that will go inside the orbit of the Earth (1 AU) close to Venus around 2010. On this spacecraft, the 8-channel PVDF sensors of about 1 m2 detection area will be onboard to test this system in the interplanetary operation and to hopefully measure dust flux anisotropy in the trailing edge of the Earth, heliocentric flux variance inside 1 AU, and opportunistic detections of possible cometary dust trails and flux enhancement near Venus. The sensors filter electronic, thermal and vibration noises and record time, peak hold value, and relax duration of signals of micrometeoroid impacts. When the full-size solar power sail mission goes beyond 1 AU passing the main asteroid belt to 5 AU in 2010's, this dust detector system will be onboard in the order of several m2 active area. It will also compare its results with infrared observation of zodiacal

  6. Back bombardment for dispenser and lanthanum hexaboride cathodes

    NASA Astrophysics Data System (ADS)

    Bakr, Mahmoud; Kinjo, R.; Choi, Y. W.; Omer, M.; Yoshida, K.; Ueda, S.; Takasaki, M.; Ishida, K.; Kimura, N.; Sonobe, T.; Kii, T.; Masuda, K.; Ohgaki, H.; Zen, H.

    2011-06-01

    The back bombardment (BB) effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC) and lanthanum hexaboride (LaB6) thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6μs duration, the DC cathode experiences a large change in the temperature compared with LaB6, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

  7. Ion bombardment glow-discharge furnaces for atomic emission spectroscopy

    SciTech Connect

    Tanguay, S.L.

    1990-01-01

    Two glow discharge plasma devices for the atomic emission analysis of aqueous samples were investigated. The devices use thermal vaporization of samples from a graphite cathode coupled with glow-discharge excitation. Furnace heating of the cathode is accomplished by the positive ion bombardment of the cathode during plasma operation. The dc plasma operates in Ar at 0.5-5.0 torr, with currents up to 250 mA. A cw, axial magnetic field of up to 1.25 kG is applied to the cylindrical-post cathode system to reduce electron losses, thereby increasing plasma excitation and ionization efficiency. At higher currents, the cathodes heat to temperatures as high as 2,500{degree}C in the case of the cylindrical-post cathode. Hollow-cathode heating temperatures are lower under comparable conditions, due to the larger cathode surface area, greater cathode mass, and lower power dissipation. The peak furnace temperature using this configuration is approximately 2100{degree}C. The role of the emission of thermionic electrons from the hot cathodes in limiting the cathode heating and in regulating the cathode temperature are considered. Sample residues of up to 50 ng of the analyte are vaporized from the cylindrical-post cathode within a few seconds of the initiation of the discharge, resulting in a transient emission intensity profile. With the hollow-cathode furnace, vaporization may take several seconds. Although a lower rate of cathode heating and a lower sample vapor residence time results in limits of detection which are one to two orders of magnitude lower than those achieved using the cylindrical-post cathode system. For the hollow cathode, limits of detection are on the order of 10 pg to 1 ng.

  8. Whither Cometary Dust?

    NASA Astrophysics Data System (ADS)

    Lisse, Carey M.

    2010-10-01

    In this paper I will discuss recent findings that have important implications for our understanding of the formation and evolution of primitive solar system dust, including: - Nesvorny et al. (2010), following up on their dynamical analyses of the zodiacal dust bands as sourced by the breakup of the Karin (5Mya) and Veritas (8Mya) asteroid families, argue that over 90% of the interplanetary dust cloud at 1 AU comes from JFC comets with near-circularized, low inclination orbits. This implies that the noted IPD collections of anhydrous and hydrous dust particles are likely to be from Oort cloud and JFC comets, respectively, not from asteroids and comets as thought in the past. Hydrous dust particles from comets like 85P/Wild2 and 9P/Tempel 1 would be consistent with results from the STARDUST and Deep Impact experiments. - Estimates of the dust particle size distributions (PSDs) in the comae of 85P/Wild2 (Green et al. 2004, 2007) and 73P/SW-3 (Sitko et al. 2010, Vaubaillon & Reach 2010) and in the trails of comets (Reach et al. 2007) have broken power law structure, with a plateau enhancement of particles of 1 mm - 1 cm in size. This size is also the size of most chondritic inclusions, and the predicted size range of the "aggregational barrier", where collisions between dust particles become destructive. - Studies of the albedo and polarization properties of cometary dust (Kolokolova et al. 2007) suggest there are 2 major groupings, one with low scattering capability and one with high. While these families could possibly have been explained by systematics in the PSDs of the emitted dust, independent work by Lisse et al. (2008) on the mineralogy of a number of highly dusty comets has shown evidence for one family of comets with highly crystalline dust and another with highly amorphous dust.

  9. Dust Interactions on Small Solar System Bodies and Technology Considerations for Exploration

    NASA Technical Reports Server (NTRS)

    Kobrick, Ryan,; Hoffman, Jeffrey; Pavone, Marco; Street, Kenneth; Rickman, Douglas

    2014-01-01

    Small-bodies such as asteroids and Mars' moons Phobos and Deimos have relatively unknown regolith environments. It is hypothesized that dust preserved in the regolith on the surfaces will have similar mechanical properties to lunar dust because of similar formation processes from micrometeorite bombardment, low relative gravity for slow settling times, and virtually no weathering because there is no atmosphere. This combination of processes infers that small-body dust particles will be highly angular and retain abrasive properties. The focus of this paper uses the mission architecture and engineering design for an asteroid hopper known as Hedgehog, a spherical spacecraft with several symmetric spikes used to aid with tumbling mobility in a low gravity environment. Dust abrasion considerations are highlighted throughout the paper relating to the lead authors' previous work, but act as an example of one of many important dust or regolith physical properties that need to be considered for future exploration. Measurable regolith properties are summarized in order to identify technologies that may be useful for exploration in terms of scientific return and spacecraft design. Previous instruments are summarized in this paper that could be used on the Hedgehog. Opportunities for hardware payloads are highlighted that include low mass solutions or dualpurpose instruments that can measure regolith or dust properties. Finally, dust mitigation suggestions are made for vehicles of this mobility profile.

  10. The Nature of Interstellar Dust

    NASA Technical Reports Server (NTRS)

    Huss, G. R.

    2003-01-01

    The STARDUST mission is designed to collect dust the coma of comet Wild 2 and to collect interstellar dust on a second set of collectors. We have a reasonable idea of what to expect from the comet dust collection because the research community has been studying interplanetary dust particles for many years. It is less clear what we should expect from the interstellar dust. This presentation discusses what we might expect to find on the STARDUST interstellar dust collector.

  11. Combustible dust tests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sugar dust explosion in Georgia on February 7, 2008 killed 14 workers and injured many others (OSHA, 2009). As a consequence of this explosion, OSHA revised its Combustible Dust National Emphasis (NEP) program. The NEP targets 64 industries with more than 1,000 inspections and has found more tha...

  12. Pathfinder Spies Dust Devils

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This set of images from NASA's 1997 Pathfinder mission highlight the dust devils that gust across the surface of Mars. The right image shows the dusty martian sky as our eye would see it. The left image has been enhanced to expose the dust devils that lurk in the hazy sky.

  13. Dust resuspension without saltation

    PubMed Central

    Loosmore, Gwen A.; Hunt, James R.

    2010-01-01

    Wind resuspension (or entrainment) provides a source of dust and contaminants for the atmosphere. Conventional wind erosion models parameterize dust resuspension flux with a threshold velocity or with a horizontal abrasion flux; in the absence of abrasion the models assume dust flux is transient only. Our experiments with an uncrusted, fine material at relative humidities exceeding 40% show a long-term steady dust flux in the absence of abrasion, which fits the approximate form: Fd = 3.6(u*)3, where Fd is the dust flux (in μg/m2 s), and u* is the friction velocity (in m/s). These fluxes are generally too small to be significant sources of dust in most models of dust emission. However, they provide a potential route to transport contaminants into the atmosphere. In addition, dust release is substantial during the initial transient phase. Comparison with field data suggests that the particle friction Reynolds number may prove a better parameter than u* for correlating fluxes and understanding the potential for abrasion. PMID:20336175

  14. Toxicity of lunar dust

    NASA Astrophysics Data System (ADS)

    Linnarsson, Dag; Carpenter, James; Fubini, Bice; Gerde, Per; Karlsson, Lars L.; Loftus, David J.; Prisk, G. Kim; Staufer, Urs; Tranfield, Erin M.; van Westrenen, Wim

    2012-12-01

    The formation, composition and physical properties of lunar dust are incompletely characterised with regard to human health. While the physical and chemical determinants of dust toxicity for materials such as asbestos, quartz, volcanic ashes and urban particulate matter have been the focus of substantial research efforts, lunar dust properties, and therefore lunar dust toxicity may differ substantially. In this contribution, past and ongoing work on dust toxicity is reviewed, and major knowledge gaps that prevent an accurate assessment of lunar dust toxicity are identified. Finally, a range of studies using ground-based, low-gravity, and in situ measurements is recommended to address the identified knowledge gaps. Because none of the curated lunar samples exist in a pristine state that preserves the surface reactive chemical aspects thought to be present on the lunar surface, studies using this material carry with them considerable uncertainty in terms of fidelity. As a consequence, in situ data on lunar dust properties will be required to provide ground truth for ground-based studies quantifying the toxicity of dust exposure and the associated health risks during future manned lunar missions.

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

    NASA Astrophysics Data System (ADS)

    Hoerth, Tobias; Schäfer, Frank

    2016-04-01

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

  16. 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

  17. The lunar dust pendulum

    NASA Astrophysics Data System (ADS)

    Collier, Michael R.; Farrell, William M.; Stubbs, Timothy J.

    2013-07-01

    An analytic model for the motion of a positively charged lunar dust grain in the presence of a shadowed crater at a negative potential in vacuum is presented. It is shown that the dust grain executes oscillatory trajectories, and an expression is derived for the period of oscillation. Simulations used to verify the analytic expression also show that because the trajectories are unstable, dust grains are either ejected from the crater's vicinity or deposited into the crater forming "dust ponds." The model also applies to other airless bodies in the solar system, such as asteroids, and predicts that under certain conditions, particularly near lunar sunset, oscillating dust "canopies" or "swarms" will form over negatively charged craters.

  18. Dust escape from Io

    NASA Astrophysics Data System (ADS)

    Flandes, Alberto

    2004-08-01

    The Dust ballerina skirt is a set of well defined streams composed of nanometric sized dust particles that escape from the Jovian system and may be accelerated up to >=200 km/s. The source of this dust is Jupiter's moon Io, the most volcanically active body in the Solar system. The escape of dust grains from Jupiter requires first the escape of these grains from Io. This work is basically devoted to explain this escape given that the driving of dust particles to great heights and later injection into the ionosphere of Io may give the particles an equilibrium potential that allow the magnetic field to accelerate them away from Io. The grain sizes obtained through this study match very well to the values required for the particles to escape from the Jovian system.

  19. Lunar Dust Mitigation Screens

    NASA Astrophysics Data System (ADS)

    Knutson, Shawn; Holloway, Nancy

    With plans for the United States to return to the moon, and establish a sustainable human presence on the lunar surface many issues must be successfully overcome. Lunar dust is one of a number of issues with the potential to create a myriad of problems if not adequately addressed. Samples of dust brought back from Apollo missions show it to be soft, yet sharp and abrasive. The dust consists of a variety of morphologies including spherical, angular blocks, shards, and a number of irregular shapes. One of the main issues with lunar dust is its attraction to stick to anything it comes in contact with (i.e. astronauts, equipment, habitats, etc.). Ionized radiation from the sun strikes the moon's surface and creates an electrostatic charge on the dust. Further, the dust harbors van der Waals forces making it especially difficult to separate once it sticks to a surface. During the Apollo missions, it was discovered that trying to brush the lunar dust from spacesuits was not effective, and rubbing it caused degradation of the suit material. Further, when entering the lunar module after moonwalks, the astronauts noted that the dust was so prolific inside the cabin that they inhaled and ingested it, causing at least one of them, Harrison "Jack" Schmidt, to report irritation of the throat and lungs. It is speculated that the dust could also harm an astronaut's nervous and cardiovascular systems, especially during an extended stay. In addition to health issues, the dust can also cause problems by scouring reflective coatings off of thermal blankets, and roughening surfaces of windows and optics. Further, panels on solar cells and photovoltaics can also be compromised due to dust sticking on the surfaces. Lunar dust has the capacity to penetrate seals, interfere with connectors, as well as mechanisms on digging machines, all of which can lead to problems and failure. To address lunar dust issues, development of electrostatic screens to mitigate dust on sur-faces is currently

  20. Loire Dust Devil

    NASA Technical Reports Server (NTRS)

    2005-01-01

    25 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an active dust devil making its way across the rugged terrain of the Loire Vallis system. The dust devil, seen as a fuzzy, nearly-circular bright feature near the center of the picture, is casting a shadow toward the right/upper right (east/northeast). Unlike some martian dust devils, this one did not make a dark streak on the ground. Many more dust devils occur on Mars than there are dust devil streaks observed on the planet's surface.

    Location near: 18.2oS, 16.5oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

  1. Isidis Dust Devil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    10 March 2004 This arrow in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image points to an active dust devil observed in Isidis Planitia near 18.3oN, 268.9oW. The columnar shadow of the dust devil is visible, as is a pencil-thin (at least, pencil-thin at the scale of the image) line created by the vortex as it disrupted the dust that coats the surface. The streak indicates that the dust devil had already traveled more than 3 kilometers (1.9 miles), over craters, large ripples, and ridges, before the MOC took this picture. The dust devil was moving from the northeast (upper right) toward the southwest (lower left). Sunlight illuminates the scene from the lower left; the image covers an area 3 km (1.9 mi) wide.

  2. Techniques for in situ collection and measurement of volatiles released during hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Heppner, R. A.; Niu, William; Maag, Carl R.

    1994-01-01

    The capability of the gas capture cell to collect particles and semivolatile species which were released during impact is examined. The proposed Comet Coma Sample Return (CCSR) payload contains a variety of instrumentation for characterizing and collecting cometary dust. In this suite of instruments the Gas Capture Cell (GCC) is unique in that it not only collects the vaporization products resulting from the dust particle impacts, but also provides chemical characterization information prior to return of the dust particles for analysis on Earth. The GCC provides near real-time characterization of the volatile species, such as low- and medium-molecular-weight organic compounds that evolve from dust particles on impact with metal targets. Instrument sensitivity is sufficient for analyzing the volatile impact products resulting from single, individual dust particles. This capability will enable characterization of near-pristine dust particles, including the CHON particles, to be performed at a level not previously possible. Its design concept, operation and performance are detailed.

  3. Early inner solar system impactors: physical properties of comet nuclei and dust particles revisited.

    PubMed

    Levasseur-Regourd, A C; Lasue, J; Desvoivres, E

    2006-12-01

    During the epoch of early bombardment, terrestrial planets have been heavily impacted by cometary nuclei and cometary dust particles progressively injected in the interplanetary medium. Stardust and Deep Impact missions confirm that the nuclei are porous, loosely consolidated objects, with densities below 1,000 kg m(-3), and that they often release small fragments of ices and dust. Recent numerical simulations of the light scattering properties of cometary dust particles indicate that they are highly porous, most likely fractal, and rich in absorbing organics compounds (with a mixture ratio of e.g. 33 to 60% in mass for comet Hale-Bopp). Taking into account the fact that porous structures survive more easily than compact ones during atmospheric entry, such results reinforce the scenario of the early terrestrial planets enrichment--in organics needed for life to originate--by comets. PMID:17120128

  4. Theory and mitigation of electron back-bombardment in thermionic cathode radio frequency guns

    NASA Astrophysics Data System (ADS)

    Edelen, Jonathan Paul

    Photocathode RF guns are currently the standard for high- power, low-emittance beam generation in free-electron lasers. These devices require the use of high-power lasers (which are bulky and expensive to operate) and high-quantum-efficiency cathodes (which have limited lifetimes requiring frequent replacement). The use of RF-gated thermionic cathodes enables operation without a large drive laser and with long lifetimes. One major limitation of RF-gated thermionic cathodes is that electrons emitted late in the RF period will not gain enough energy to exit the gun before being accelerated back towards the cathode by the change in sign of the RF field. These electrons deposit their kinetic energy on the cathode surface in the form of heat, limiting the ability to control the output current from the cathode. This dissertation is aimed at understanding the fundamental design factors that drive the back-bombardment process and at exploring novel techniques to reduce its impact on a high-current system. This begins with the development of analytic models that predict the back-bombardment process in single-cell guns. These models are compared with simulation and with a measurement taken at a specific facility. This is followed by the development of analytic models that predict the effects of space-charge on back-bombardment. These models are compared with simulations. This is followed by an analysis of how the addition of multiple cells will impact the back-bombardment process. Finally, a two-frequency gun is studied for its ability to mitigate the back-bombardment process. This dissertation provides new insight on how the back-bombardment process scales as a function of the beam parameters and how space-charge affects this process. Additionally this dissertation shows how a second frequency can be used to mitigate the back-bombardment effect.

  5. 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.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Boubert, Douglas; Evans, N. Wyn

    2016-07-01

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

  9. 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

  10. 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.

  11. 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).

  12. 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.

  13. 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.

  14. 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.

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

    SciTech Connect

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

    2010-11-01

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

  16. Ground Testing Of Hypervelocity Impact Effects Of Micrometeoroids And Space Debris On Solar Arrays

    NASA Astrophysics Data System (ADS)

    Schimmerohn, Martin; Rott, Martin; Gerhard, Andreas; Osterholz, Jens; Schafer, Frank; D'Accolti, Gianfelice

    2011-10-01

    Solar arrays are the satellite component most exposed to micrometeoroid and space debris (MM/SD) impacts. The damage potential of hypervelocity impacts (HVI) is characterized by considerable energy released at the impact interface leading to mechanical damage and the generation of plasma. Impact experiments performed in the past indicate that the impact plasma can induce arcing, which consequently may lead to permanent power losses as known from electrostatic discharges. An ESA study is currently ongoing, the objective of which is to study and test the susceptibility of state-of-the art solar arrays to HVI. This paper describes potential failure modes, a ground testing approach to simulate them and its implementation for the test campaign, which will be performed at Fraunhofer EMI using a light gas gun and at Technische Universität München using a plasma-dynamic accelerator. Solar array simulation equipment and comprehensive plasma diagnostics are to be applied for ground testing.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Modelling hypervelocity impact fracture of ceramic panels using a mesh-free method

    NASA Astrophysics Data System (ADS)

    Das, R.; Mikhail, J.; Cleary, P. W.

    2010-06-01

    This paper studies the application of Smoothed Particle Hydrodynamics (SPH) for modelling hyper-velocity impact fracture and fragmentation in ceramic panels. Numerical modelling of complex fracture processes is important to understand the fundamental failure mechanisms in a variety of systems. Finite Element Method (FEM) is the mesh-based method conventionally applied to numerical simulation of fracture and fragmentation. However, the mesh generation and manipulation do not often provide the desired accuracy of the solutions, especially in problems with extreme deformations and discontinuities. To overcome this, here we use a mesh-free method called Smoothed Particle Hydrodynamic (SPH) to investigate the three-dimensional fracture of ceramic panels. The effect of impact speed on the fracture pattern and energy transfer is analysed. The SPH simulations are found to be robust in understanding the fracture mechanisms and in providing crucial design parameters.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. PAH bombardment by energetic particles: models and astrophysical implications

    NASA Astrophysics Data System (ADS)

    Micelotta, E.; Jones, A.; Tielens, A.

    2011-05-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of the Interstellar Medium (ISM) of galaxies. Interstellar PAHs are apparently able to withstand the rigors of the harsh environment of the ISM for some some 100 million years and thus are resilient against processing by UV and X-ray photons and supernova shock waves. PAHs in space are mainly studied through their characteristic emission bands, due to infrared fluorescence following the absorption of UV photons. This is the reason why the photophysics of PAHs in space has been extensively investigated. On the other hand, PAHs are also strongly affected by collisional processes, i.e. bombardment by high-velocity ions and electrons, arising from interstellar shocks, hot gas and cosmic rays. However, very little was known about the physics of the interaction between PAHs and high energy particles, especially in terms of PAH damage and destruction. This lack of information had made the interpretation of PAH observations difficult in regions subjected to such processes. Our research aims to fill this key gap in our understanding of the physics behind collisional processing of PAHs and to clarify how this affects the PAH evolution in the astrophysical context. We first describe the models we have developed, that take into account the molecular nature of the target PAH and allow for the first time a quantitative description of the collisional processing of PAH molecules by ions and electrons with energies between 10 eV and 10 keV (in shocks and hot gas) and between 5 MeV and 10 GeV (in cosmic rays). Specific models were needed because PAHs are molecules and not small solid fragments, thus the classical approach from solid state physics cannot be applied. We then show the applications of our models to observations, estimating the lifetime of PAHs against collisional processing in specific objects. We discuss the astrophysical implications of our findings on the considered sample, which

  8. Compositional and Geochronological Constraints on the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Cohen, Barbara

    2007-10-01

    Radiometric dating and compositional clustering of lunar impact-melt rocks form the backbone of the lunar cataclysm hypothesis. Precise age determinations of Apollo and Luna impact-melt rocks, lunar meteorite impact-melt clasts, lunar soil spherules, and lunar glass fragments define the classic formulation of the late heavy bombardment: a sharp peak at 3.9 Ga, a steep decline after 3.9 Ga perhaps only 20-200 Myr long, and few, if any, positively identified rocks of impact origin prior to 4.0 Ga. Geological associations between compositional groups of impact-melt rocks and specific impact basins imply that five large basins formed on the Moon within 200 Myr. A counterargument says that all, or nearly all, the 3.9-Ga impact melt rocks are products of the Imbrium basin-forming impact. It is still a matter of debate whether this hypothesis can accommodate the multiple groups of impact melt that are resolvable from each other in age and in trace-element composition. The 3.9 Ga age peak and subsequent steep decline are not well mirrored in meteorite data. Radiometric ages in ordinary chondrites and HED meteorites peak around 3.9 Ga but ages older and younger than 3.9 Ga are common. We have a single shock age for Martian meteorites: ALH 84001 crystallized at 4.50 Ga but was shocked at 3.92 ± 0.04 Ga. Differences in relative impact velocity, impact-melt production, and sampling rate could explain some of the differences between the meteorite and lunar records. One way to anchor the early end of the lunar flux would be to directly sample the impact-melt sheet of a large lunar basin distant from Imbrium, such as the South Pole-Aitken basin, where a large amount of melt probably still resides on the basin floor and could be directly sampled by a human or robotic mission. B.A.C. is supported by NASA Cosmochemistry grant #NNX07AI57G.

  9. Wobbling The Galactic Disk with Bombardment of Satellite Galaxies

    NASA Astrophysics Data System (ADS)

    D'Onghia, Elena

    We propose to assess the effect of impacts of large visible satellite galaxies on a disk, as well as the relevance of the continuing bombardment of the Galactic disk by dark matter clumps as predicted by the current cosmological framework that can wobble the disk, heating it and eventually exciting ragged spiral structures. In particular, we make detailed predictions for observable features such as spiral arms, rings and their associated stars in galactic disks and relate them to the physical processes that drive their formation and evolution in our Milky Way galaxy and nearby spirals. To do this, we will combine analytic methods and numerical simulations that allow us to calculate observables, which we will compare to present and forthcoming observations. Our methodology utilizes a combination of state of the art hydrodynamic simulations of galaxy evolution and multi- wavelength radiative transfer simulations. Our primary goals are: (1) To identify the physical processes that are responsible for spiral structure formation observed in our Milky Way and nearby disk galaxies, from the flocculent to grand- designed spiral galaxies and to provide observable signatures to be compared with data on nearby galaxies combining maps of 24 micron emission (Spitzer) and cold gas, CO (Heracles) and HI (THINGS). (2) To explore different morphologies of spiral galaxies: from the multi-armed galaxies to the Milky Way sized galaxies with few arms. (3) For a Milky Way disk we will assess the effect of impacts of substructures passing through the disk to origin the asymmetry in the number density of stars recently discovered from SDSS and SEGUE data and confirmed from RAVE data. We will also investigate the disk heating in the vertical plane due to the formation of vertical oscillations that are produced by the impact and migration of stars in the disk as consequence of the heating as compared to the classical stellar migration mechanism. (4) We will measure the spiral pattern speed

  10. Purity and cleanness of aerogel as a cosmic dust capture medium

    NASA Technical Reports Server (NTRS)

    Tsou, P.; Fleming, R. H.; Lindley, P. M.; Craig, A. Y.; Blake, D.

    1994-01-01

    The capability for capturing micrometeoroids intact through laboratory simulations and in space in passive underdense silica aerogel offers a valuable tool for cosmic dust research. The integrity of the sample handling medium can substantially modify the integrity of the sample. Intact capture is a violent hypervelocity event: the integrity of the capturing medium can cause even greater modification of the sample. Doubts of the suitability of silica aerogel as a capture medium were raised at the 20th LPSC, and questions were raised again at the recent workshop on Particle Capture, Recovery, and Velocity Trajectory Measurement Technologies. Assessment of aerogel's volatile components and carbon contents have been made. We report the results of laboratory measurements of the purity and cleanliness of silica aerogel used for several Sample Return Experiments flown on the Get Away Special program.

  11. 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

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

    SciTech Connect

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

    1980-01-01

    Parametric system studies of an inertial confinement fusion (ICF) reactor system to transmute fission products from a LWR economy have been carried out. The ICF reactors would produce net power in addition to transmuting fission products. The particular ICF concept examined is an impact fusion approach termed HYPERFUSE, in which hypervelocity pellets, traveling on the order of 100 to 300 km/sec, collide with each other or a target block in a reactor chamber and initiate a thermonuclear reaction. The DT fusion fuel is contained in a shell of the material to be transmuted, e.g., /sup 137/Cs, /sup 90/Sr, /sup 129/I, /sup 99/Tc, etc. The 14-MeV fusion neutrons released during the pellet burn cause transmutation reactions (e.g., (n,2n), (n,..cap alpha..), (n,..gamma..), etc.) that convert the long-lived fission products (FP's) either to stable products or to species that decay with a short half-life to a stable product. The transmutation parametric studies conclude that the design of the hypervelocity projectiles should emphasize the achievement of high densities in the transmutation regions (greater than the DT fusion fuel density), as well as the DT ignition and burn criterion (rho R = 1.0 to 3.0) requirements. These studies also indicate that masses on the order of 1.0 g at densities of rho greater than or equal to 500.0 g/cm/sup 3/ are required for a practical fusion-based fission product transmutation system.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Dust in circumstellar disks

    NASA Astrophysics Data System (ADS)

    Rodmann, Jens

    2006-02-01

    This thesis presents observational and theoretical studies of the size and spatial distribution of dust particles in circumstellar disks. Using millimetre interferometric observations of optically thick disks around T Tauri stars, I provide conclusive evidence for the presence of millimetre- to centimetre-sized dust aggregates. These findings demonstrate that dust grain growth to pebble-sized dust particles is completed within less than 1 Myr in the outer disks around low-mass pre-main-sequence stars. The modelling of the infrared spectral energy distributions of several solar-type main-sequence stars and their associated circumstellar debris disks reveals the ubiquity of inner gaps devoid of substantial amounts of dust among Vega-type infrared excess sources. It is argued that the absence of circumstellar material in the inner disks is most likely the result of the gravitational influence of a large planet and/or a lack of dust-producing minor bodies in the dust-free region. Finally, I describe a numerical model to simulate the dynamical evolution of dust particles in debris disks, taking into account the gravitational perturbations by planets, photon radiation pressure, and dissipative drag forces due to the Poynting-Robertson effect and stellar wind. The validity of the code it established by several tests and comparison to semi-analytic approximations. The debris disk model is applied to simulate the main structural features of a ring of circumstellar material around the main-sequence star HD 181327. The best agreement between model and observation is achieved for dust grains a few tens of microns in size locked in the 1:1 resonance with a Jupiter-mass planet (or above) on a circular orbit.

  18. Dust control for Enabler

    NASA Technical Reports Server (NTRS)

    Hilton, Kevin; Karl, Chad; Litherland, Mark; Ritchie, David; Sun, Nancy

    1992-01-01

    The dust control group designed a system to restrict dust that is disturbed by the Enabler during its operation from interfering with astronaut or camera visibility. This design also considers the many different wheel positions made possible through the use of artinuation joints that provide the steering and wheel pitching for the Enabler. The system uses a combination of brushes and fenders to restrict the dust when the vehicle is moving in either direction and in a turn. This design also allows for each of maintenance as well as accessibility of the remainder of the vehicle.

  19. Dust control for Enabler

    NASA Technical Reports Server (NTRS)

    Hilton, Kevin; Karl, Chad; Litherland, Mark; Ritchie, David; Sun, Nancy

    1992-01-01

    The dust control group designed a system to restrict dust that is disturbed by the Enabler during its operation from interfering with astronaut or camera visibility. This design also considers the many different wheel positions made possible through the use of artinuation joints that provide the steering and wheel pitching for the Enabler. The system uses a combination of brushes and fenders to restrict the dust when the vehicle is moving in either direction and in a turn. This design also allows for ease of maintenance as well as accessibility of the remainder of the vehicle.

  20. Dust in the Mediterranean

    NASA Technical Reports Server (NTRS)

    2002-01-01

    On July 24, the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), acquired this true-color image of a large cloud of dust blowing from northern Africa across the Mediterranean Sea. The dust storm has persisted in the region for at least a week. In this image, the brownish dust plume appears to originate about 260 miles (400 km) east of Algiers, Algeria, and is blowing toward the northwest coast of Sardinia, Italy. SeaWiFS flies aboard the OrbView-2 Satellite. Image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE

  1. Electrostatic dust detector

    DOEpatents

    Skinner, Charles H.

    2006-05-02

    An apparatus for detecting dust in a variety of environments which can include radioactive and other hostile environments both in a vacuum and in a pressurized system. The apparatus consists of a grid coupled to a selected bias voltage. The signal generated when dust impacts and shorts out the grid is electrically filtered, and then analyzed by a signal analyzer which is then sent to a counter. For fine grids a correlation can be developed to relate the number of counts observed to the amount of dust which impacts the grid.

  2. Ultra-low-energy (<10 eV/u) ion beam bombardment effect on naked DNA

    NASA Astrophysics Data System (ADS)

    Thopan, P.; Thongkumkoon, P.; Prakrajang, K.; Suwannakachorn, D.; Yu, L. D.

    2014-05-01

    Since ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range, it is very interesting to know effects from ultra-low-energy ion interaction with DNA for understanding ion-beam-induced genetic mutation. Tens-keV Ar- and N-ion beams were decelerated to ultra-low energy ranging from 20 to 100 eV, or only a few to 10 eV/u, to bombard naked plasmid DNA. The bombarded DNA was analyzed using gel electrophoresis for DNA form changes. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks after bombarded by tens-eV ion beam. N-ion beam was found more effective in inducing DNA change and mutation than Ar-ion beam. The study demonstrated that the ion bombardment with energy as low as several-tens eV was able to break DNA strands and thus potentially to cause genetic modification of biological cells. The experimental results were discussed in terms of direct atomic collision between the ions and DNA atoms.

  3. Dust mite (image)

    MedlinePlus

    This is a magnified photograph of a dust mite. Mites are carriers (vectors) of many important diseases including typhus (scrub and murine) and rickettsialpox. (Image courtesy of the Centers for Disease ...

  4. Dusts and Molds

    MedlinePlus

    ... of dust can result in sensitization. Symptoms include chills, fever, cough, chest congestion, fatigue, and shortness of ... grain and forage products. Symptoms include cough, fever, chills, body aches, and fatigue. These symptoms appear from ...

  5. 1983 Transatlantic Dust Event

    NASA Video Gallery

    This visualization (prepared in 2001) shows dust being blown westward over the Atlantic from northern Africa in early 1983, from aerosol measurements taken by Nimbus 7's TOMS instrument. Saharan du...

  6. Adhesion of Lunar Dust

    NASA Astrophysics Data System (ADS)

    Walton, Otis R.

    2007-04-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  7. The Lunar Dust Pendulum

    NASA Technical Reports Server (NTRS)

    Collier, Michael R.; Stubbs, Timothy J.; Farrell, William M.

    2011-01-01

    Shadowed regions on the lunar surface acquire a negative potential. In particular, shadowed craters can have a negative potential with respect to the surrounding lunar regolith in sunlight, especially near the terminator regions. Here we analyze the motion of a positively charged lunar dust grain in the presence of a shadowed crater at a negative potential in vacuum. Previous models describing the transport of charged lunar dust close to the surface have typically been limited to one-dimensional motion in the vertical direction, e.g. electrostatic levitation; however, the electric fields in the vicinity of shadowed craters will also have significant components in the horizontal directions. We propose a model that includes both the horizontal and vertical motion of charged dust grains near shadowed craters. We show that the dust grains execute oscillatory trajectories and present an expression for the period of oscillation drawing an analogy to the motion of a pendulum.

  8. The Lunar Dust Pendulum

    NASA Technical Reports Server (NTRS)

    Kuntz, Kip; Collier, Michael R.; Stubbs, Timothy J.; Farrell, William M.

    2011-01-01

    Shadowed regions on the lunar surface acquire a negative potential. In particular, shadowed craters can have a negative potential with respect to the surrounding lunar regolith in sunlight, especially near the terminator regions. Here we analyze the motion of a positively charged lnnar dust grain in the presence of a shadowed crater at a negative potential in vacuum. Previous models describing the transport of charged lunar dust close to the surface have typically been limited to one-dimensional motion in the vertical direction, e.g. electrostatic levitation; however. the electric fields in the vicinity of shadowed craters will also have significant components in the horizontal directions. We propose a model that includes both the horizontal and vertical motion of charged dust grains near shadowed craters. We show that the dust grains execute oscillatory trajectories and present an expression for the period of oscillation drawing an analogy to the motion of a pendulum.

  9. Adhesion of Lunar Dust

    NASA Technical Reports Server (NTRS)

    Walton, Otis R.

    2007-01-01

    This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

  10. Dust and Smoke

    Atmospheric Science Data Center

    2014-05-15

    ... dust, the most common non-spherical aerosol type, from pollution and forest fire particles. Determining aerosol characteristics is a ... higher, indicating the relative abundance of small pollution particles, especially over the Atlantic where the aerosol optical ...

  11. 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.

  12. Bombardment of thin lithium films with energetic plasma flows

    NASA Astrophysics Data System (ADS)

    Gray, Travis Kelly

    The Divertor Erosion and Vapor Shielding Experiment (DEVEX) has been constructed in the Center for Plasma-Material Interactions at the University of Illinois at Urbana-Champaign. It consists of a conical theta-pinch connected to a 60 kV, 36 muF capacitor bank which is switched with a rise time of 3.5 mus. This results in a peak current of 300 kA for a 30 kV charge on the capacitor bank. The resulting plasma is created and compressed under the theta-pinch coil and then expelled axially towards a target chamber due to the conical taper of the theta-coil. The plasma that reaches the target chamber is dense, 1021 m-3 and cool, 10--20 eV. For the purposes of this study, a thin stainless steel target, sputter coated with a lithium magnetron is the target/material of interest. Both computational [A. Hassanein, Fus. Eng. Des. 60: 527546 (2002)] and experimental [M.L. Apicella, et al., J. Nuc. Mater. 386--388:821823 (2009)] studies have shown that lithium, under fusion relevant plasma bombardment, maintains a much lower surface temperature than other plasma facing materials such as tungsten or carbon. This is believed clue to the strong evaporation and/or sputtering of lithium under these conditions. Subsequently a vapor cloud is formed in front of the plasma-facing surface. The lithium vapor interacts with the incident plasma stream absorbing a fraction of the incident plasma energy via the lithium-plasma interactions. Here, we present experimental verification of substantially reduced target surface temperature with the use of thin lithium films on surface of the target as compared to a bare target. Furthermore, optical measurements are made to determine the density and temperature of the lithium vapor cloud as it expands away from the target surface. A collisional-radiative model for both neutrals and singly ionized lithium is used to model the lithium vapor and is found to correlate well with the optical measurements. The vapor cloud electron temperature is found to

  13. 'Bubble chamber model' of fast atom bombardment induced processes.

    PubMed

    Kosevich, Marina V; Shelkovsky, Vadim S; Boryak, Oleg A; Orlov, Vadim V

    2003-01-01

    A hypothesis concerning FAB mechanisms, referred to as a 'bubble chamber FAB model', is proposed. This model can provide an answer to the long-standing question as to how fragile biomolecules and weakly bound clusters can survive under high-energy particle impact on liquids. The basis of this model is a simple estimation of saturated vapour pressure over the surface of liquids, which shows that all liquids ever tested by fast atom bombardment (FAB) and liquid secondary ion mass spectrometry (SIMS) were in the superheated state under the experimental conditions applied. The result of the interaction of the energetic particles with superheated liquids is known to be qualitatively different from that with equilibrium liquids. It consists of initiation of local boiling, i.e., in formation of vapour bubbles along the track of the energetic particle. This phenomenon has been extensively studied in the framework of nuclear physics and provides the basis for construction of the well-known bubble chamber detectors. The possibility of occurrence of similar processes under FAB of superheated liquids substantiates a conceptual model of emission of secondary ions suggested by Vestal in 1983, which assumes formation of bubbles beneath the liquid surface, followed by their bursting accompanied by release of microdroplets and clusters as a necessary intermediate step for the creation of molecular ions. The main distinctive feature of the bubble chamber FAB model, proposed here, is that the bubbles are formed not in the space and time-restricted impact-excited zone, but in the nearby liquid as a 'normal' boiling event, which implies that the temperature both within the bubble and in the droplets emerging on its burst is practically the same as that of the bulk liquid sample. This concept can resolve the paradox of survival of intact biomolecules under FAB, since the part of the sample participating in the liquid-gas transition via the bubble mechanism has an ambient temperature

  14. 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.

  15. The Galileo dust detector

    NASA Technical Reports Server (NTRS)

    Gruen, E.; Fechtig, H.; Hanner, M. S.; Kissel, J.; Lindblad, B. A.; Linkert, D.; Maas, D.; Morfill, G. E.; Zook, H. A.

    1990-01-01

    The Galileo Dust Detector is intended to provide direct observations of dust grains with masses between 10(sup -19) kg and 10(sup -9) kg in interplanetary space and in the Jovian system, to investigate their physical and dynamical properties as functions of the distances to the Sun, to Jupiter and to its satellites, to study its interaction with the Galilean satellites and the Jovian magnetosphere. Surface phenomena of the satellites (like albedo variations), which might be effects of meteoroid impacts will be compared with the dust environment. Electric charges of particulate matter in the magnetosphere and its consequences will be studied; e.g. the effects of the magnetic field on the trajectories of dust particles and fragmentation of particles due to electrostatic disruption. The investigation is performed with an instrument that measures the mass, speed, flight direction and electric charge of individual dust particles. It is a multi-coincidence detector with a mass sensitivity 10(sup 6) times higher than that of previous in-situ experiments which measured dust in the outer solar system. The instrument weighs 4.2 kg, consumes 2.4 W, and has a normal data transmission rate of 24 bits/s in nominal spacecraft tracking mode. On December 29, 1989 the instrument was switched-on. After the instrument had been configured to flight conditions cruise science data collection started immediately. In the period to May 18, 1990 at least 168 dust impacts have been recorded. For 81 of these dust grains, masses and impact speeds have been determined. First flux values are also given.

  16. ION TRAPPING AND CATHODE BOMBARDMENT BY TRAPPED IONS IN DC PHOTOGUNS.

    SciTech Connect

    POZDEYEV,E.

    2007-06-25

    DC photoguns are used to produce high-quality, high-intensity electron beams for accelerator driven applications. Ion bombardment is believed to be the major cause of degradation of the photocathode efficiency. Additionally to ions produced in the accelerating cathode-anode gap, the electron beam can ionize the residual gas in the transport line. These ions are trapped transversely within the beam and can drift back to the accelerating gap and contribute to the bombardment rate of the cathode. This paper proposes a method to reduce the flow of ions produced in the beam transport line and drifting back to the cathode-anode gap by introducing a positive potential barrier that repels the trapped ions. The reduced ion bombardment rate and increased life time of photocathodes will reduce the downtime required to service photoinjectors and associated costs.

  17. Depth resolution improvement in secondary ion mass spectrometry analysis using metal cluster complex ion bombardment

    SciTech Connect

    Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S.

    2006-07-31

    Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir{sub 4}(CO){sub 7}{sup +} as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of {approx}1 nm under 5 keV, 45 deg. condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5 keV with higher incident angles.

  18. Titanium dioxide surface modification via ion-beam bombardment for vertical alignment of nematic liquid crystal.

    PubMed

    Na, Hyun-Jae; Lee, Jin-Woo; Lee, Won-Kyu; Lim, Ji-Hun; Park, Hong-Gyu; Kim, Byoung-Yong; Hwang, Jeong-Yeon; Han, Jeong-Min; Seo, Dae-Shik

    2010-04-15

    We introduce the characteristics of the titanium dioxide (TiO(2)) inorganic film deposited by rf magnetron sputtering for liquid crystal display applications. The TiO(2) films demonstrated vertical alignment (VA) of the liquid crystals (LCs) obtained by using ion-beam (IB) bombardment. As observed by using x-ray photoelectron spectroscopy, the chemical structure of the TiO(2) was changed by IB bombardment, altering the Ti-O bonding of the Ti 2p spectra to lower intensity levels. Breaking Ti-O bonding by IB bombardment created pretilt angles between the TiO(2) film and LC molecules. The better voltage-transmittance characteristics of the VA LCDs based on TiO(2) film were measured and compared with the same characteristics of polyimide film. PMID:20410949

  19. Simulation studies on back bombardment of electrons in rf thermionic guns

    NASA Astrophysics Data System (ADS)

    Liu, Hongxiu

    1991-05-01

    Using SUPERFISH and PARMELA, we simulate the back bombardment dynamics of electrons in rf thermionic guns. First, we shed light on some basic physical pictures of the back bombardment by means of the simulation results. Then the solution to this problem is investigated through applying a transverse magnetic field vertically traversing the cathode cavity. The Glaser profile is assumed for the magnetic field. It shows that for the total emitted charge of 1.65 nC and the rf duty factor of 2.5×10 -5 the average back bombardment power can be reduced from more than 10 W to about 2 W with the varying magnetic field up to 150 G. The influence of the magnetic field on the normal electrons out of the gun cavity is examined. The correction to this influence is investigated. Some conclusions are drawn finally.

  20. Secondary ion emission from V and Al surfaces under keV light ion on bombardment

    NASA Astrophysics Data System (ADS)

    Blauner, Patricia G.; Weller, Martha R.; Kaurin, Michael G.; Weller, Robert A.

    1986-03-01

    Positive secondary ion mass spectra have been measured for oxidized polycrystalline V and Al targets bombarded by H +, H 2+, He + and Ar + ions with beam energies ranging from 25 keV to 275 keV. An enhancement in the relative yield of positive ions of electronegative surface constituents, in particular O + is observed under light ion bombardment. Metallic ion intensities were found to decrease with increasing primary beam energy in proportion to the estimated total sputtering yields for these targets and beams. In contrast, the O + secondary ion intensities were independent of primary beam energy. This behavior is similar to that observed previously with heavy ions of comparable velocities. In addition, for the projectiles and targets used in these measurements, no energy thresholds or collective effects were observed in the emission of any positive ion. Published data on secondary ion emission resulting from electron, photon, and heavy ion bombardment are compared with these results.